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1.  Poly(Ethylene Oxide)-Modified Poly(β-Amino Ester) Nanoparticles as a pH-Sensitive System for Tumor-Targeted Delivery of Hydrophobic Drugs: Part I. In Vitro Evaluations 
Molecular pharmaceutics  2005;2(5):357-366.
A representative poly(β-amino ester) (PbAE) with biodegradable and pH-sensitive properties was used to formulate nanoparticle-based dosage form for tumor-targeted paclitaxel delivery. The polymer undergoes rapid dissolution when the pH of the medium is less than 6.5, and hence is expected to release its contents at once within the acidic tumor microenvironment and endo/lysosome compartments of cells. PbAE nanoparticles were prepared by solvent displacement method and characterized for particle size, charge, and surface morphology. Pluronic® F-108, a triblock copolymer of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) was blended with PbAE to induce surface modification of the nanoparticles. In vitro cellular uptake of tritiated [3H] paclitaxel in solution form and as nanoparticulate formulation was studied in MDA-MB-231 human breast adenocarcinoma cells grown in 12-well plates. We also examined the intracellular degradation pattern of the formulations within the cells by estimating the drug release profile. Cytotoxicity assay was performed on the formulations at different doses and time intervals. Nanoparticles prepared from poly(ε-caprolactone) (PCL) that do not display pH-sensitive release behavior were used as control. Spherical nanoparticles having positive zeta potential (~ 40 mV) were obtained in the size range of 150–200 nm with PbAE. The PEO chains of the Pluronic® were well-anchored within the nanomatrix as determined by electron spectroscopy for chemical analysis (ESCA). The intracellular accumulation of paclitaxel within tumor cells was significantly higher when administered in the nanoparticle formulations as compared to aqueous solution. Qualitative fluorescent microscopy confirmed the rapid release of the payload in case of PbAE nanoparticles into the cytosol, while the PCL nanoparticles integrity remained intact. The cytotoxicity assay results showed significantly higher tumoricidal activity of paclitaxel when administered in the nanoparticle formulations. The cell-kill effect was maximal for paclitaxel-loaded PbAE nanoparticles when normalized with respect to intracellular drug concentrations. Thus, PEO-modified PbAE nanoparticles show tremendous potential as novel carriers of cytotoxic agents for achieving improved drug disposition and enhanced efficacy.
doi:10.1021/mp0500420
PMCID: PMC1350920  PMID: 16196488
Biodegradable; pH-sensitive; nanoparticles; poly(β-amino ester); cytotoxicity; triggered-release; paclitaxel
2.  Actively-targeted LTVSPWY peptide-modified magnetic nanoparticles for tumor imaging 
Background
Magnetic resonance imaging (MRI) is widely used in modern clinical medicine as a diagnostic tool, and provides noninvasive and three-dimensional visualization of biological phenomena in living organisms with high spatial and temporal resolution. Therefore, considerable attention has been paid to magnetic nanoparticles as MRI contrast agents with efficient targeting ability and cellular internalization ability, which make it possible to offer higher contrast and information-rich images for detection of disease.
Methods
LTVSPWY peptide-modified PEGylated chitosan (LTVSPWY-PEG-CS) was synthesized by chemical reaction, and the chemical structure was confirmed by 1H-NMR. LTVSPWY-PEG-CS-modified magnetic nanoparticles were prepared successfully using the solvent diffusion method. Their particle size, size distribution, and zeta potential were measured by dynamic light scattering and electrophoretic mobility, and their surface morphology was investigated by transmission electron microscopy. To investigate their selective targeting ability, the cellular uptake of the LTVSPWY-PEG-CS-modified magnetic nanoparticles was observed in a cocultured system of SKOV-3 cells which overexpress HER2 and A549 cells which are HER2-negative. The in vitro cytotoxicity of these nanoparticles in SKOV-3 and A549 cells was measured using the MTT method. The SKOV-3-bearing nude mouse model was used to investigate the tumor targeting ability of the magnetic nanoparticles in vivo.
Results
The average diameter and zeta potential of the LTVSPWY-PEG-CS-modified magnetic nanoparticles was 267.3 ± 23.4 nm and 30.5 ± 7.0 mV, respectively, with a narrow size distribution and spherical morphology. In vitro cytotoxicity tests demonstrated that these magnetic nanoparticles were carriers suitable for use in cancer diagnostics with low toxicity. With modification of the LTVSPWY homing peptide, magnetic nanoparticles could be selectively taken up by SKOV-3 cells overexpressing HER2 when cocultured with HER2-negative A549 cells. In vivo biodistribution results suggest that treatment with LTVSPWY-PEG-CS-modified magnetic nanoparticles/DiR enabled tumors to be identified and diagnosed more rapidly and efficiently in vivo.
Conclusion
LTVSPWY-PEG-CS-modified magnetic nanoparticles are a promising contrast agent for early detection of tumors overexpressing HER2 and further diagnostic application.
doi:10.2147/IJN.S33593
PMCID: PMC3410692  PMID: 22866005
LTVSPWY peptide; HER2; poly(ethylene glycol); chitosan; magnetic nanoparticles; tumor targeting
3.  A green chemistry approach for synthesizing biocompatible gold nanoparticles 
Nanoscale Research Letters  2014;9(1):248.
Gold nanoparticles (AuNPs) are a fascinating class of nanomaterial that can be used for a wide range of biomedical applications, including bio-imaging, lateral flow assays, environmental detection and purification, data storage, drug delivery, biomarkers, catalysis, chemical sensors, and DNA detection. Biological synthesis of nanoparticles appears to be simple, cost-effective, non-toxic, and easy to use for controlling size, shape, and stability, which is unlike the chemically synthesized nanoparticles. The aim of this study was to synthesize homogeneous AuNPs using pharmaceutically important Ganoderma spp. We developed a simple, non-toxic, and green method for water-soluble AuNP synthesis by treating gold (III) chloride trihydrate (HAuCl4) with a hot aqueous extract of the Ganoderma spp. mycelia. The formation of biologically synthesized AuNPs (bio-AuNPs) was characterized by ultraviolet (UV)-visible absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray (EDX), dynamic light scattering (DLS), and transmission electron microscopy (TEM). Furthermore, the biocompatibility of as-prepared AuNPs was evaluated using a series of assays, such as cell viability, lactate dehydrogenase leakage, and reactive oxygen species generation (ROS) in human breast cancer cells (MDA-MB-231). The color change of the solution from yellow to reddish pink and strong surface plasmon resonance were observed at 520 nm using UV-visible spectroscopy, and that indicated the formation of AuNPs. DLS analysis revealed the size distribution of AuNPs in liquid solution, and the average size of AuNPs was 20 nm. The size and morphology of AuNPs were investigated using TEM. The biocompatibility effect of as-prepared AuNPs was investigated in MDA-MB-231 breast cancer cells by using various concentrations of AuNPs (10 to 100 μM) for 24 h. Our findings suggest that AuNPs are non-cytotoxic and biocompatible. To the best of our knowledge, this is the first report to describe the synthesis of monodispersed, biocompatible, and soluble AuNPs with an average size of 20 nm using Ganoderma spp. This study opens up new possibilities of using an inexpensive and non-toxic mushroom extract as a reducing and stabilizing agent for the synthesis of size-controlled, large-scale, biocompatible, and monodispersed AuNPs, which may have future diagnostic and therapeutic applications.
doi:10.1186/1556-276X-9-248
PMCID: PMC4035729  PMID: 24940177
AuNPs; Biocompatibility; Ganoderma spp; Human breast cancer cells; Transmission electron microscopy; UV-visible spectroscopy
4.  A Novel Docetaxel-Loaded Poly (ε-Caprolactone)/Pluronic F68 Nanoparticle Overcoming Multidrug Resistance for Breast Cancer Treatment 
Nanoscale Research Letters  2009;4(12):1530-1539.
Multidrug resistance (MDR) in tumor cells is a significant obstacle to the success of chemotherapy in many cancers. The purpose of this research is to test the possibility of docetaxel-loaded poly (ε-caprolactone)/Pluronic F68 (PCL/Pluronic F68) nanoparticles to overcome MDR in docetaxel-resistance human breast cancer cell line. Docetaxel-loaded nanoparticles were prepared by modified solvent displacement method using commercial PCL and self-synthesized PCL/Pluronic F68, respectively. PCL/Pluronic F68 nanoparticles were found to be of spherical shape with a rough and porous surface. The nanoparticles had an average size of around 200 nm with a narrow size distribution. The in vitro drug release profile of both nanoparticle formulations showed a biphasic release pattern. There was an increased level of uptake of PCL/Pluronic F68 nanoparticles in docetaxel-resistance human breast cancer cell line, MCF-7 TAX30, when compared with PCL nanoparticles. The cytotoxicity of PCL nanoparticles was higher than commercial Taxotere® in the MCF-7 TAX30 cell culture, but the differences were not significant (p > 0.05). However, the PCL/Pluronic F68 nanoparticles achieved significantly higher level of cytotoxicity than both of PCL nanoparticles and Taxotere® (p < 0.05), indicating docetaxel-loaded PCL/Pluronic F68 nanoparticles could overcome multidrug resistance in human breast cancer cells and therefore have considerable potential for treatment of breast cancer.
doi:10.1007/s11671-009-9431-6
PMCID: PMC2894322  PMID: 20652101
Nanoparticles; MDR; Pluronic F68; Poly (ε-caprolactone); Docetaxel; Breast cancer
5.  A Novel Docetaxel-Loaded Poly (ε-Caprolactone)/Pluronic F68 Nanoparticle Overcoming Multidrug Resistance for Breast Cancer Treatment 
Nanoscale Research Letters  2009;4(12):1530-1539.
Multidrug resistance (MDR) in tumor cells is a significant obstacle to the success of chemotherapy in many cancers. The purpose of this research is to test the possibility of docetaxel-loaded poly (ε-caprolactone)/Pluronic F68 (PCL/Pluronic F68) nanoparticles to overcome MDR in docetaxel-resistance human breast cancer cell line. Docetaxel-loaded nanoparticles were prepared by modified solvent displacement method using commercial PCL and self-synthesized PCL/Pluronic F68, respectively. PCL/Pluronic F68 nanoparticles were found to be of spherical shape with a rough and porous surface. The nanoparticles had an average size of around 200 nm with a narrow size distribution. The in vitro drug release profile of both nanoparticle formulations showed a biphasic release pattern. There was an increased level of uptake of PCL/Pluronic F68 nanoparticles in docetaxel-resistance human breast cancer cell line, MCF-7 TAX30, when compared with PCL nanoparticles. The cytotoxicity of PCL nanoparticles was higher than commercial Taxotere®in the MCF-7 TAX30 cell culture, but the differences were not significant (p > 0.05). However, the PCL/Pluronic F68 nanoparticles achieved significantly higher level of cytotoxicity than both of PCL nanoparticles and Taxotere®(p < 0.05), indicating docetaxel-loaded PCL/Pluronic F68 nanoparticles could overcome multidrug resistance in human breast cancer cells and therefore have considerable potential for treatment of breast cancer.
doi:10.1007/s11671-009-9431-6
PMCID: PMC2894322  PMID: 20652101
Nanoparticles; MDR; Pluronic F68; Poly (ε-caprolactone); Docetaxel; Breast cancer
6.  Multifunctional polymeric nanoparticles doubly loaded with SPION and ceftiofur retain their physical and biological properties 
Background
Advances in nanostructure materials are leading to novel strategies for drug delivery and targeting, contrast media for magnetic resonance imaging (MRI), agents for hyperthermia and nanocarriers. Superparamagnetic iron oxide nanoparticles (SPIONs) are useful for all of these applications, and in drug-release systems, SPIONs allow for the localization, direction and concentration of drugs, providing a broad range of therapeutic applications. In this work, we developed and characterized polymeric nanoparticles based on poly (3-hydroxybutyric acid-co-hydroxyvaleric acid) (PHBV) functionalized with SPIONs and/or the antibiotic ceftiofur. These nanoparticles can be used in multiple biomedical applications, and the hybrid SPION–ceftiofur nanoparticles (PHBV/SPION/CEF) can serve as a multifunctional platform for the diagnosis and treatment of cancer and its associated bacterial infections.
Results
Morphological examination using transmission electron microscopy (TEM) showed nanoparticles with a spherical shape and a core-shell structure. The particle size was evaluated using dynamic light scattering (DLS), which revealed a diameter of 243.0 ± 17 nm. The efficiency of encapsulation (45.5 ± 0.6% w/v) of these polymeric nanoparticles was high, and their components were evaluated using spectroscopy. UV–VIS, FTIR and DSC showed that all of the nanoparticles contained the desired components, and these compounds interacted to form a nanocomposite. Using the agar diffusion method and live/dead bacterial viability assays, we demonstrated that these nanoparticles have antimicrobial properties against Escherichia coli, and they retain their magnetic properties as measured using a vibrating sample magnetometer (VSM). Cytotoxicity was assessed in HepG2 cells using live/dead viability assays and MTS, and these assays showed low cytotoxicity with IC50 > 10 mg/mL nanoparticles.
Conclusions
Our results indicate that hybrid and multifunctional PHBV/SPION/CEF nanoparticles are suitable as a superparamagnetic drug delivery system that can guide, concentrate and site–specifically release drugs with antibacterial activity.
Electronic supplementary material
The online version of this article (doi:10.1186/s12951-015-0077-5) contains supplementary material, which is available to authorized users.
doi:10.1186/s12951-015-0077-5
PMCID: PMC4334767
PHBV; SPION; Ceftiofur; Polymeric nanoparticles; Drug delivery; Superparamagnetic nanoparticles
7.  The role of surface charge on the uptake and biocompatibility of hydroxyapatite nanoparticles with osteoblast cells 
Nanotechnology  2011;22(10):105708.
The objective of this study is to evaluate the effect of hydroxyapatite (HAP) nanoparticles with different surface charges on the cellular uptake behavior and in vitro cell viability and proliferation of MC3T3-E1 cell lines (osteoblast). The nanoparticles surface charge was varied by the surface modification with two carboxylic acids: 12-aminododecanoic acid (positive) and dodecanedioic acid (negative). The untreated HAP nanoparticles and dodecanoic acid modified HAP nanoparticles (neutral) were used as the control. X-ray diffraction (XRD) revealed that surface modifications by the three carboxylic acids did not change the crystal structure of HAP nanoparticles; Fourier transform infrared spectroscopy (FTIR) confirmed the adsorption and binding of the carboxylic acids on HAP nanoparticle surface; and zeta potential measurement confirmed that the chemicals successfully modified the surface charge of HAP nanoparticles in water based solution. Transmission electron microscopy (TEM) images showed that positively charged, negatively charged and untreated HAP nanoparticles, with similar size and shape, all penetrated into the cells and cells had more uptake of HAP nanoparticles with positive charge compared to those with negative charge, which might be attributed to the attractive or repulsive interaction between the negatively charged cell membrane and positively/negatively charged HAP nanoparticles. The neutral HAP nanoparticles could not penetrate cell membrane due to the larger size. MTT assay and LDH assay results indicated that as compared with the polystyrene control, greater cell viability and cell proliferation were measured on MC3T3-E1 cells treated with the three kinds of the HAP nanoparticles (neutral, positive, and untreated), among which positively charged HAP nanoparticles shows strongest improvement for cell viability and cell proliferation. In summary, the surface charge of HAP nanoparticles can be modified to influence the cellular uptake of HAP nanoparticles and the different uptake also influence the behavior of cells. These in-vitro results may also provide useful information for investigations of HAP nanoparticles applications in the gene delivery and intracellular drug delivery.
doi:10.1088/0957-4484/22/10/105708
PMCID: PMC3144725  PMID: 21289408
8.  Effects of magnetic cobalt ferrite nanoparticles on biological and artificial lipid membranes 
Background
The purpose of this work is to provide experimental evidence on the interactions of suspended nanoparticles with artificial or biological membranes and to assess the possibility of suspended nanoparticles interacting with the lipid component of biological membranes.
Methods
1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid vesicles and human red blood cells were incubated in suspensions of magnetic bare cobalt ferrite (CoFe2O4) or citric acid (CA)-adsorbed CoFe2O4 nanoparticles dispersed in phosphate-buffered saline and glucose solution. The stability of POPC giant unilamellar vesicles after incubation in the tested nanoparticle suspensions was assessed by phase-contrast light microscopy and analyzed with computer-aided imaging. Structural changes in the POPC multilamellar vesicles were assessed by small angle X-ray scattering, and the shape transformation of red blood cells after incubation in tested suspensions of nanoparticles was observed using scanning electron microscopy and sedimentation, agglutination, and hemolysis assays.
Results
Artificial lipid membranes were disturbed more by CA-adsorbed CoFe2O4 nanoparticle suspensions than by bare CoFe2O4 nanoparticle suspensions. CA-adsorbed CoFe2O4-CA nanoparticles caused more significant shape transformation in red blood cells than bare CoFe2O4 nanoparticles.
Conclusion
Consistent with their smaller sized agglomerates, CA-adsorbed CoFe2O4 nanoparticles demonstrate more pronounced effects on artificial and biological membranes. Larger agglomerates of nanoparticles were confirmed to be reactive against lipid membranes and thus not acceptable for use with red blood cells. This finding is significant with respect to the efficient and safe application of nanoparticles as medicinal agents.
doi:10.2147/IJN.S57671
PMCID: PMC3970951  PMID: 24741305
CoFe2O4; nanoparticles; agglomerates; human red blood cells; lipid vesicles
9.  Synthesis of Silver Nanoparticles Using Hydroxyl Functionalized Ionic Liquids and Their Antimicrobial Activity 
We report a new one phase method for the synthesis of uniform monodisperse crystalline Ag nanoparticles in aqueous systems that has been developed by using newly synthesized mono and dihydroxylated ionic liquids and cationic surfactants based on 1,3-disubstituted imidazolium cations and halogens anions. The hydroxyl functionalized ionic liquids (HFILs) and hydroxyl functionalized cationic surfactants (HFCSs) also simultaneously acts both as the reductant and protective agent. By changing the carbon chain length, alcohol structure and anion of the 1,3-imidazolium based HFILs and HFCSs the particle size, uniform and dispersibility of nanoparticles in aqueous solvents could be controlled. Transmission electron microscopy (TEM), electron diffraction, UV-Vis and NMR, were used for characterization of HFILs, HFCSs and silver nanoparticles. TEM studies on the solution showed representative spherical silver nanoparticles with average sizes 2–8 nm, particularly 2.2 nm and 4.5 nm in size range and reasonable narrow particle size distributions (SD-standard distribution) 0.2 nm and 0.5 nm respectively. The all metal nanoparticles are single crystals with face centered cubic (fcc) structure. The silver nanoparticles surface of plasmon resonance band (λmax) around 420 nm broadened and little moved to the long wavelength region that indicating the formation of silver nanoparticles dispersion with broad absorption around infrared (IR) region. Silver complexes of these HFILs as well as different silver nanoparticles dispersions have been tested in vitro against several gram positive and gram negative bacteria and fungus. The silver nanoparticles providing environmentally friendly and high antimicrobial activity agents.
doi:10.3390/ijms9050807
PMCID: PMC2635708  PMID: 19325785
Silver nanoparticles; hydroxyl functionalized ionic liquids; hydroxyl functionalized cationic surfactants; antimicrobial activity
10.  Biocompatible Polysiloxane-Containing Diblock Copolymer PEO-b-PγMPS for Coating Magnetic Nanoparticles 
ACS applied materials & interfaces  2009;1(10):2134-2140.
We report a biocompatible polysiloxane containing amphiphilic diblock copolymer, poly(ethylene oxide)-block-poly(γ-methacryloxypropyltrimethoxysilane) (PEO-b-PγMPS), for coating and stabilizing nanoparticles for biomedical applications. Such amphiphilic diblock copolymer which comprises both a hydrophobic segment with “surface anchoring moiety” (silane group) and a hydrophilic segment with PEO (Mn=5000 g/mol) was obtained by the reversible addition fragmentation chain transfer (RAFT) polymerization using the PEO macromolecular chain transfer agent. When used for coating paramagnetic iron oxide nanoparticles (IONPs), copolymers were mixed with hydrophobic oleic acid coated core size uniformed IONPs (D=13 nm) in co-solvent tetrahydrofuran. After being aged over a period of time, resulting monodispersed IONPs can be transferred into aqueous medium. With proper PγMPS block length (Mn=10,000 g/mol), polysiloxane containing diblock copolymers formed a thin layer of coating (~3 nm) around monocrystalline nanoparticles as measured by transmission electron microscopy (TEM). Magnetic resonance imaging (MRI) experiments showed excellent T2 weighted contrast effect from coated IONPs with a transverse relaxivity r2=98.6 mM−1s−1 (at 1.5 Tesla). Such thin coating layer has little effect on the relaxivity when compared to that of IONPs coated with conventional amphiphilic copolymer. Polysiloxane containing diblock copolymer coated IONPs are stable without aggregation or binding to proteins in serum when incubated for 24 h in culture medium containing 10% serum. Furthermore, much lower level of intracellular uptake by macrophage cells was observed with polysiloxane containing diblock copolymers coated IONPs, suggesting the reduction of non-specific cell uptakes and antibiofouling effect.
doi:10.1021/am900262j
PMCID: PMC2799899  PMID: 20161520
diblock copolymer; silanes; coating; nanoparticle; magnetic resonance imaging
11.  Enhanced cellular uptake of aminosilane-coated superparamagnetic iron oxide nanoparticles in mammalian cell lines 
Purpose
To compare the cellular uptake efficiency and cytotoxicity of aminosilane (SiO2-NH2)-coated superparamagnetic iron oxide (SPIO@SiO2-NH2) nanoparticles with three other types of SPIO nanoparticles coated with SiO2 (SPIO@SiO2), dextran (SPIO@dextran), or bare SPIO in mammalian cell lines.
Materials and methods
Four types of monodispersed SPIO nanoparticles with a SPIO core size of 7 nm and an overall size in a range of 7–15 nm were synthesized. The mammalian cell lines of MCF-7, MDA-MB-231, HT-29, RAW264.7, L929, HepG2, PC-3, U-87 MG, and mouse mesenchymal stem cells (MSCs) were incubated with four types of SPIO nanoparticles for 24 hours in the serum-free culture medium Dulbecco’s modified Eagle’s medium (DMEM) with 4.5 μg/mL iron concentration. The cellular uptake efficiencies of SPIO nanoparticles were compared by Prussian blue staining and intracellular iron quantification. In vitro magnetic resonance imaging of MSC pellets after SPIO labeling was performed at 3 T. The effect of each SPIO nanoparticle on the cell viability of RAW 264.7 (mouse monocyte/macrophage) cells was also evaluated.
Results
Transmission electron microscopy demonstrated surface coating with SiO2-NH2, SiO2, and dextran prevented SPIO nanoparticle aggregation in DMEM culture medium. MCF-7, MDA-MB-231, and HT-29 cells failed to show notable iron uptake. For all the remaining six cell lines, Prussian blue staining and intracellular iron quantification demonstrated that SPIO@ SiO2-NH2 nanoparticles had the highest cellular uptake efficiency. SPIO@SiO2-NH2, bare SPIO, and SPIO@dextran nanoparticles did not affect RAW 264.7 cell viability up to 200 μg Fe/mL, while SPIO@SiO2 reduced RAW 264.7 cell viability from 10 to 200 μg Fe/mL in a dose-dependent manner.
Conclusion
Cellular uptake efficiency of SPIO nanoparticles depends on both the cell type and SPIO surface characteristics. Aminosilane surface coating enhanced the cellular uptake efficiency without inducing cytotoxicity in a number of cell lines.
doi:10.2147/IJN.S28316
PMCID: PMC3289449  PMID: 22393292
magnetic nanoparticles; SPIO; iron oxide; surface coating; cellular uptake
12.  Development and characterization of chitosan-PEG-TAT nanoparticles for the intracellular delivery of siRNA 
Recently, cell-penetrating peptides have been proposed to translocate antibodies, proteins, and other molecules in targeted drug delivery. The proposed study presents the synthesis and characterization of a peptide-based chitosan nanoparticle for small interfering RNA (siRNA) delivery, in-vitro. Specifically, the synthesis included polyethylene glycol (PEG), a hydrophilic polymer, and trans-activated transcription (TAT) peptide, which were chemically conjugated on the chitosan polymer. The conjugation was achieved using N-Hydroxysuccinimide-PEG-maleimide (heterobifunctional PEG) as a cross-linker, with the bifunctional PEG facilitating the amidation reaction through its N-Hydroxysuccinimide group and reacting with the amines on chitosan. At the other end of PEG, the maleimide group was chemically conjugated with the cysteine-modified TAT peptide. The degree of substitution on chitosan with PEG and on PEG with TAT was confirmed using colorimetric assays. The resultant polymer was used to form nanoparticles complexing siRNA, which were then characterized for particle size, morphology, cellular uptake, and cytotoxicity. The nanoparticles were tested in-vitro on mouse neuroblastoma cells (Neuro2a). Particle size and surface charge were characterized and an optimal pH condition and PEG molecular weight were determined to form sterically stable nanoparticles. Results indicate 7.5% of the amines in chitosan polymer were conjugated to the PEG and complete conjugation of TAT peptide was observed on the synthesized PEGylated chitosan polymer. Compared with unmodified chitosan nanoparticles, the nanoparticles formed at pH 6 were monodispersed and of <100 nm in size, exhibiting maximum cell transfection ability and very low cytotoxicity. Thus, this research may be of significance in translocating biotherapeutic molecules for intracellular delivery applications.
doi:10.2147/IJN.S43683
PMCID: PMC3666663  PMID: 23723699
chemical conjugation; peptide; transfection; polymer; synthesis; in-vitro
13.  Acceleration of gene transfection efficiency in neuroblastoma cells through polyethyleneimine/poly(methyl methacrylate) core-shell magnetic nanoparticles 
Background
The purpose of this study was to demonstrate the potential of magnetic poly(methyl methacrylate) (PMMA) core/polyethyleneimine (PEI) shell (mag-PEI) nanoparticles, which possess high saturation magnetization for gene delivery. By using mag-PEI nanoparticles as a gene carrier, this study focused on evaluation of transfection efficiency under magnetic induction. The potential role of this newly synthesized nanosphere for therapeutic delivery of the tryptophan hydroxylase-2 (TPH-2) gene was also investigated in cultured neuronal LAN-5 cells.
Methods
The mag-PEI nanoparticles were prepared by one-step emulsifier-free emulsion polymerization, generating highly loaded and monodispersed magnetic polymeric nanoparticles bearing an amine group. The physicochemical properties of the mag-PEI nanoparticles and DNA-bound mag-PEI nanoparticles were investigated using the gel retardation assay, atomic force microscopy, and zeta size measurements. The gene transfection efficiencies of mag-PEI nanoparticles were evaluated at different transfection times. Confocal laser scanning microscopy confirmed intracellular uptake of the magnetoplex. The optimal conditions for transfection of TPH-2 were selected for therapeutic gene transfection. We isolated the TPH-2 gene from the total RNA of the human medulla oblongata and cloned it into an expression vector. The plasmid containing TPH-2 was subsequently bound onto the surfaces of the mag-PEI nanoparticles via electrostatic interaction. Finally, the mag-PEI nanoparticle magnetoplex was delivered into LAN-5 cells. Reverse-transcriptase polymerase chain reaction was performed to evaluate TPH-2 expression in a quantitative manner.
Results
The study demonstrated the role of newly synthesized high-magnetization mag-PEI nanoparticles for gene transfection in vitro. The expression signals of a model gene, luciferase, and a therapeutic gene, TPH-2, were enhanced under magnetic-assisted transfection. An in vitro study in neuronal cells confirmed that using mag-PEI nanoparticles as a DNA carrier for gene delivery provided high transfection efficiency with low cytotoxicity.
Conclusion
The mag-PEI nanoparticle is a promising alternative gene transfection reagent due to its ease of use, effectiveness, and low cellular toxicity. The mag-PEI nanoparticle is not only practical for gene transfection in cultured neuronal cells but may also be suitable for transfection in other cells as well.
doi:10.2147/IJN.S32311
PMCID: PMC3373300  PMID: 22701321
magnetic nanoparticle; non-viral vector; gene delivery; tryptophan hydroxylase-2; LAN-5; neuronal cells
14.  Synthesis and optimization of chitosan nanoparticles: Potential applications in nanomedicine and biomedical engineering 
Background: Chitosan nanoparticles have become of great interest for nanomedicine, biomedical engineering and development of new therapeutic drug release systems with improved bioavailability, increased specificity and sensitivity, and reduced pharmacological toxicity. The aim of the present study was to synthesis and optimize of the chitosan nanoparticles for industrial and biomedical applications.
Methods: Fe3O4 was synthesized and optimized as magnetic core nanoparticles and then chitosan covered this magnetic core. The size and morphology of the nano-magnetic chitosan was analyzed by scanning electron microscope (SEM). Topography and size distribution of the nanoparticles were shown with two-dimensional and three-dimensional images of atomic force microscopy (AFM). The nanoparticles were analyzed using transmission electron microscopy (TEM).
Results: The chitosan nanoparticles prepared in the experiment exhibited white powder shape. The SEM micrographs of the nano-magnetic chitosan showed that they were approximately uniform spheres. The unmodified chitosan nanoparticles composed of clusters of nanoparticles with sizes ranging from 10 nm to 80 nm. AFM provides a three-dimensional surface profile. The TEM image showed physical aggregation of the chitosan nanoparticles.
Conclusion: The results show that a novel chitosan nanoparticle was successfully synthesized and characterized. It seems that this nanoparticle like the other chitosan nano particles has potential applications for nanomedicine, biomedical engineering, industrial and pharmaceutical fields.
PMCID: PMC4143737  PMID: 25202443
Nanomedicine; Nanoparticle; Chitosan; Biomedical engineering.
15.  Chitosan–Pluronic nanoparticles as oral delivery of anticancer gemcitabine: preparation and in vitro study 
Nanoparticles have proven to be an effective delivery system with few side effects for anticancer drugs. In this study, gemcitabine-loaded nanoparticles have been prepared by an ionic gelation method using chitosan and Pluronic® F-127 as a carrier. Prepared nanoparticles were characterized using dynamic light scattering, Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), scanning electron microscopy, and transmission electron microscopy. Different parameters such as concentration of sodium tripolyphosphate, chitosan, Pluronic, and drug on the properties of the prepared nanoparticles were evaluated. In vitro drug release was studied in phosphate-buffered saline (PBS; pH = 7.4). The cytotoxicity of the nanoparticles was assayed in the HT-29 colon cancer cell line. The mucoadhesion behavior of the nanoparticles was also studied by mucus glycoprotein assay. The prepared nanoparticles had a spherical shape with positive charge and a mean diameter ranging between 80 to 170 nm. FT-IR and DSC studies found that the drug was dispersed in its amorphous form due to its potent interaction with nanoparticle matrix. Maximum drug encapsulation efficiency was achieved at 0.4 mg/mL gemcitabine while maximum drug loading was 6% obtained from 0.6 mg/mL gemcitabine. An in vitro drug release study at 37°C in PBS (pH = 7.4) exhibited a controlled release profile for chitosan–Pluronic® F-127 nanoparticles. A cytotoxicity assay of gemcitabine-loaded nanoparticles showed an increase in the cytotoxicity of gemcitabine embedded in the nanoparticles in comparison with drug alone. The mucoadhesion study results suggest that nanoparticles could be considered as an efficient oral formulation for colon cancer treatment.
doi:10.2147/IJN.S26365
PMCID: PMC3352690  PMID: 22605934
chitosan; nanoparticles; ionic gelation; gemcitabine; mucoadhesion; oral drug delivery; anticancer
16.  Albumin-based Nanoconjugates for Targeted Delivery of Therapeutic Oligonucleotides 
Biomaterials  2013;34(32):10.1016/j.biomaterials.2013.06.066.
Nanoparticle-based delivery has become an important strategy to advance siRNA and antisense oligonucleotides into clinical reality. However, limited biodistribution of nanoparticles and the toxicity of some nanocarriers restrict the wider application of this strategy. To address these issues we aimed to construct oligonucleotide delivery systems which are non-cytotoxic and smaller than typical nanoparticles. Thus, a morpholino oligonucleotide was conjugated to a tumor-targeting RGD peptide, and then, multiple RGD-oligo conjugates were linked to a single molecule of human serum albumin via a reductively responsive linkage. The resultant nanoconjugates showed uniform and monodispersed size distribution with a diameter of 13 nm. A single nanoconjugate molecule contains 15 oligonucleotides as well as 15 targeting ligands on the surface of albumin. The nanoparticle demonstrated 61-fold enhancement in receptor-specific cellular delivery of oligonucleotides in integrin-expressing tumor cells compared to the non-targeted control nanoconjugates and were able to robustly enhance functional activity of the oligonucleotide at low nanomolar concentrations without causing cytotoxicity. Due to their small size, the targeted nanoconjugates could penetrate deeply and distribute throughout 3-D tumor spheroids, whereas the conventional nanoparticles with sizes over 300 nm could only deliver to the cells on the surface of the tumor spheroids. As a result of their greater cellular delivery, smaller size, and lack of cytotoxicity compared to conventional nanoparticles, the multivalent nanoconjugates may provide an effective tool for targeting oligonucleotides to tumors and other diseased tissues.
doi:10.1016/j.biomaterials.2013.06.066
PMCID: PMC3810404  PMID: 23876758
Targeted delivery; Therapeutic Oligonucleotides; Albumin; Conjugation
17.  Magnetic nanoparticle density mapping from the magnetically induced displacement data: a simulation study 
Background
Magnetic nanoparticles are gaining great roles in biomedical applications as targeted drug delivery agents or targeted imaging contrast agents. In the magnetic nanoparticle applications, quantification of the nanoparticle density deposited in a specified region is of great importance for evaluating the delivery of the drugs or the contrast agents to the targeted tissues. We introduce a method for estimating the nanoparticle density from the displacement of tissues caused by the external magnetic field.
Methods
We can exert magnetic force to the magnetic nanoparticles residing in a living subject by applying magnetic gradient field to them. The nanoparticles under the external magnetic field then exert force to the nearby tissues causing displacement of the tissues. The displacement field induced by the nanoparticles under the external magnetic field is governed by the Navier's equation. We use an approximation method to get the inverse solution of the Navier's equation which represents the magnetic nanoparticle density map when the magnetic nanoparticles are mechanically coupled with the surrounding tissues. To produce the external magnetic field inside a living subject, we propose a coil configuration, the Helmholtz and Maxwell coil pair, that is capable of generating uniform magnetic gradient field. We have estimated the coil currents that can induce measurable displacement in soft tissues through finite element method (FEM) analysis.
Results
From the displacement data obtained from FEM analysis of a soft-tissue-mimicking phantom, we have calculated nanoparticle density maps. We obtained the magnetic nanoparticle density maps by approximating the Navier's equation to the Laplacian of the displacement field. The calculated density maps match well to the original density maps, but with some halo artifacts around the high density area. To induce measurable displacement in the living tissues with the proposed coil configuration, we need to apply the coil currents as big as 104A.
Conclusions
We can obtain magnetic nanoparticle maps from the magnetically induced displacement data by approximating the Navier's equation under the assumption of uniform-gradient of the external magnetic field. However, developing a coil driving system with the capacity of up to 104A should be a great technical challenge.
doi:10.1186/1475-925X-11-11
PMCID: PMC3310781  PMID: 22394477
18.  Biosynthesis, Antimicrobial and Cytotoxic Effect of Silver Nanoparticles Using a Novel Nocardiopsis sp. MBRC-1 
BioMed Research International  2013;2013:287638.
The biosynthesis of nanoparticles has been proposed as a cost effective environmental friendly alternative to chemical and physical methods. Microbial synthesis of nanoparticles is under exploration due to wide biomedical applications, research interest in nanotechnology and microbial biotechnology. In the present study, an ecofriendly process for the synthesis of nanoparticles using a novel Nocardiopsis sp. MBRC-1 has been attempted. We used culture supernatant of Nocardiopsis sp. MBRC-1 for the simple and cost effective green synthesis of silver nanoparticles. The reduction of silver ions occurred when silver nitrate solution was treated with the Nocardiopsis sp. MBRC-1 culture supernatant at room temperature. The nanoparticles were characterized by UV-visible, TEM, FE-SEM, EDX, FTIR, and XRD spectroscopy. The nanoparticles exhibited an absorption peak around 420 nm, a characteristic surface plasmon resonance band of silver nanoparticles. They were spherical in shape with an average particle size of 45 ± 0.15 nm. The EDX analysis showed the presence of elemental silver signal in the synthesized nanoparticles. The FTIR analysis revealed that the protein component in the form of enzyme nitrate reductase produced by the isolate in the culture supernatant may be responsible for reduction and as capping agents. The XRD spectrum showed the characteristic Bragg peaks of 1 2 3, 2 0 4, 0 4 3, 1 4 4, and 3 1 1 facets of the face centered cubic silver nanoparticles and confirms that these nanoparticles are crystalline in nature. The prepared silver nanoparticles exhibited strong antimicrobial activity against bacteria and fungi. Cytotoxicity of biosynthesized AgNPs against in vitro human cervical cancer cell line (HeLa) showed a dose-response activity. IC50 value was found to be 200 μg/mL of AgNPs against HeLa cancer cells. Further studies are needed to elucidate the toxicity and the mechanism involved with antimicrobial and anticancer activity of the synthesized AgNPs as nanomedicine.
doi:10.1155/2013/287638
PMCID: PMC3727093  PMID: 23936787
19.  Gold-Coated Iron Composite Nanospheres Targeted the Detection of Escherichia coli 
We report the preparation and characterization of spherical core-shell structured Fe3O4–Au magnetic nanoparticles, modified with two component self-assembled monolayers (SAMs) consisting of 3–mercaptophenylboronic acid (3–MBA) and 1–decanethiol (1–DT). The rapid and room temperature synthesis of magnetic nanoparticles was achieved using the hydroxylamine reduction of HAuCl4 on the surface of ethylenediaminetetraacetic acid (EDTA)-immobilized iron (magnetite Fe3O4) nanoparticles in the presence of an aqueous solution of hexadecyltrimetylammonium bromide (CTAB) as a dispersant. The reduction of gold on the surface of Fe3O4 nanoparticles exhibits a uniform, highly stable, and narrow particle size distribution of Fe3O4–Au nanoparticles with an average diameter of 9 ± 2 nm. The saturation magnetization value for the resulting nanoparticles was found to be 15 emu/g at 298 K. Subsequent surface modification with SAMs against glucoside moieties on the surface of bacteria provided effective magnetic separation. Comparison of the bacteria capturing efficiency, by means of different molecular recognition agents 3–MBA, 1–DT and the mixed monolayer of 3–MBA and 1–DT was presented. The best capturing efficiency of E. coli was achieved with the mixed monolayer of 3–MBA and 1–DT-modified nanoparticles. Molecular specificity and selectivity were also demonstrated by comparing the surface-enhanced Raman scattering (SERS) spectrum of E. coli-nanoparticle conjugates with bacterial growth media.
doi:10.3390/ijms14036223
PMCID: PMC3634437  PMID: 23507756
magnetic gold nanoparticle; SERS; immunomagnetic separation; E. coli; surface functionalisation of particles
20.  Laser ablation-based one-step generation and bio-functionalization of gold nanoparticles conjugated with aptamers 
Background
Bio-conjugated nanoparticles are important analytical tools with emerging biological and medical applications. In this context, in situ conjugation of nanoparticles with biomolecules via laser ablation in an aqueous media is a highly promising one-step method for the production of functional nanoparticles resulting in highly efficient conjugation. Increased yields are required, particularly considering the conjugation of cost-intensive biomolecules like RNA aptamers.
Results
Using a DNA aptamer directed against streptavidin, in situ conjugation results in nanoparticles with diameters of approximately 9 nm exhibiting a high aptamer surface density (98 aptamers per nanoparticle) and a maximal conjugation efficiency of 40.3%. We have demonstrated the functionality of the aptamer-conjugated nanoparticles using three independent analytical methods, including an agglomeration-based colorimetric assay, and solid-phase assays proving high aptamer activity. To demonstrate the general applicability of the in situ conjugation of gold nanoparticles with aptamers, we have transferred the method to an RNA aptamer directed against prostate-specific membrane antigen (PSMA). Successful detection of PSMA in human prostate cancer tissue was achieved utilizing tissue microarrays.
Conclusions
In comparison to the conventional generation of bio-conjugated gold nanoparticles using chemical synthesis and subsequent bio-functionalization, the laser-ablation-based in situ conjugation is a rapid, one-step production method. Due to high conjugation efficiency and productivity, in situ conjugation can be easily used for high throughput generation of gold nanoparticles conjugated with valuable biomolecules like aptamers.
doi:10.1186/1477-3155-8-21
PMCID: PMC2939592  PMID: 20731831
21.  Synthesis of Amine-stabilized Aqueous Colloidal Iron Oxide Nanoparticles 
Crystal growth & design  2007;7(3):471-475.
We demonstrate a simple one-step process for the synthesis of iron oxide nanoparticle aqueous colloids using the multifunctional molecule, dodecylamine (DDA), that electrostatically complexes with aqueous iron ions (one precursor Fe2+ from FeCl2), reduces them, and subsequently caps the nanoparticles. The iron oxide particles thus synthesized are of the face-centered cubic (FCC) phase with high degree of monodispersity with appropriate concentration of amine capping molecular layer. The aqueous magnetic nanocrystalline colloids were characterized by TEM, XRD, XPS, TGA/DTA and FTIR spectroscopy techniques. The relaxivity, stability, and hydrodynamic size of the nanoparticles were investigated for potential application in magnetic resonance imaging (MRI). The magnetic properties were also studied by using a superconducting quantum interference device (SQUID) magnetometer at room temperature. We believe that such simple one-step synthesis of biocompatible aqueous nanomagnetic colloids will have viable applications in biomedical imaging, diagnostics and therapeutics.
doi:10.1021/cg060656p
PMCID: PMC2659353  PMID: 19305647
22.  Thiolated chitosan-modified PLA-PCL-TPGS nanoparticles for oral chemotherapy of lung cancer 
Oral chemotherapy is a key step towards ‘chemotherapy at home’, a dream of cancer patients, which will radically change the clinical practice of chemotherapy and greatly improve the quality of life of the patients. In this research, three types of nanoparticle formulation from commercial PCL and self-synthesized d-α-tocopheryl polyethylene glycol 1000 succinate (PLA-PCL-TPGS) random copolymer were prepared in this research for oral delivery of antitumor agents, including thiolated chitosan-modified PCL nanoparticles, unmodified PLA-PCL-TPGS nanoparticles, and thiolated chitosan-modified PLA-PCL-TPGS nanoparticles. Firstly, the PLA-PCL-TPGS random copolymer was synthesized and characterized. Thiolated chitosan greatly increases its mucoadhesiveness and permeation properties, thus increasing the chances of nanoparticle uptake by the gastrointestinal mucosa and improving drug absorption. The PLA-PCL-TPGS nanoparticles were found by FESEM that they are of spherical shape and around 200 nm in diameter. The surface charge of PLA-PCL-TPGS nanoparticles was reversed from anionic to cationic after thiolated chitosan modification. The thiolated chitosan-modified PLA-PCL-TPGS nanoparticles have significantly higher level of the cell uptake than that of thiolated chitosan-modified PLGA nanoparticles and unmodified PLA-PCL-TPGS nanoparticles. In vitro cell viability studies showed advantages of the thiolated chitosan-modified PLA-PCL-TPGS nanoparticles over Taxol® in terms of cytotoxicity against A549 cells. It seems that the mucoadhesive nanoparticles can increase paclitaxel transport by opening tight junctions and bypassing the efflux pump of P-glycoprotein. In conclusion, PLA-PCL-TPGS nanoparticles modified by thiolated chitosan could enhance the cellular uptake and cytotoxicity, which revealed a potential application for oral chemotherapy of lung cancer.
doi:10.1186/1556-276X-8-66
PMCID: PMC3598981  PMID: 23394588
Oral chemotherapy; PLA-PCL-TPGS; Thiolated chitosan; Nanoparticles; Lung cancer
23.  Simulating Magnetic Nanoparticle Behavior in Low-field MRI under Transverse Rotating Fields and Imposed Fluid Flow 
In the presence of alternating-sinusoidal or rotating magnetic fields, magnetic nanoparticles will act to realign their magnetic moment with the applied magnetic field. The realignment is characterized by the nanoparticle’s time constant, τ. As the magnetic field frequency is increased, the nanoparticle’s magnetic moment lags the applied magnetic field at a constant angle for a given frequency, Ω, in rad/s. Associated with this misalignment is a power dissipation that increases the bulk magnetic fluid’s temperature which has been utilized as a method of magnetic nanoparticle hyperthermia, particularly suited for cancer in low-perfusion tissue (e.g., breast) where temperature increases of between 4°C and 7°C above the ambient in vivo temperature cause tumor hyperthermia. This work examines the rise in the magnetic fluid’s temperature in the MRI environment which is characterized by a large DC field, B0. Theoretical analysis and simulation is used to predict the effect of both alternating-sinusoidal and rotating magnetic fields transverse to B0. Results are presented for the expected temperature increase in small tumors (~1 cm radius) over an appropriate range of magnetic fluid concentrations (0.002 to 0.01 solid volume fraction) and nanoparticle radii (1 to 10 nm). The results indicate that significant heating can take place, even in low-field MRI systems where magnetic fluid saturation is not significant, with careful The goal of this work is to examine, by means of analysis and simulation, the concept of interactive fluid magnetization using the dynamic behavior of superparamagnetic iron oxide nanoparticle suspensions in the MRI environment. In addition to the usual magnetic fields associated with MRI, a rotating magnetic field is applied transverse to the main B0 field of the MRI. Additional or modified magnetic fields have been previously proposed for hyperthermia and targeted drug delivery within MRI. Analytical predictions and numerical simulations of the transverse rotating magnetic field in the presence of B0 are investigated to demonstrate the effect of Ω, the rotating field frequency, and the magnetic field amplitude on the fluid suspension magnetization. The transverse magnetization due to the rotating transverse field shows strong dependence on the characteristic time constant of the fluid suspension, τ. The analysis shows that as the rotating field frequency increases so that Ωτ approaches unity, the transverse fluid magnetization vector is significantly non-aligned with the applied rotating field and the magnetization’s magnitude is a strong function of the field frequency. In this frequency range, the fluid’s transverse magnetization is controlled by the applied field which is determined by the operator. The phenomenon, which is due to the physical rotation of the magnetic nanoparticles in the suspension, is demonstrated analytically when the nanoparticles are present in high concentrations (1 to 3% solid volume fractions) more typical of hyperthermia rather than in clinical imaging applications, and in low MRI field strengths (such as open MRI systems), where the magnetic nanoparticles are not magnetically saturated. The effect of imposed Poiseuille flow in a planar channel geometry and changing nanoparticle concentration is examined. The work represents the first known attempt to analyze the dynamic behavior of magnetic nanoparticles in the MRI environment including the effects of the magnetic nanoparticle spin-velocity. It is shown that the magnitude of the transverse magnetization is a strong function of the rotating transverse field frequency. Interactive fluid magnetization effects are predicted due to non-uniform fluid magnetization in planar Poiseuille flow with high nanoparticle concentrations.
doi:10.1016/j.jmmm.2010.03.029
PMCID: PMC2901184  PMID: 20625540
Magnetic nanoparticles; MRI; rotating magnetic field; interactive magnetization; magnetic particle imaging
24.  Methanobactin-Mediated One-Step Synthesis of Gold Nanoparticles 
Preparation of gold nanoparticles with a narrow size distribution has enormous importance in nanotechnology. Methanobactin (Mb) is a copper-binding small peptide that appears to function as an agent for copper sequestration and uptake in methanotrophs. Mb can also bind and catalytically reduce Au (III) to Au (0). In this study, we demonstrate a facile Mb-mediated one-step synthetic route to prepare monodispersed gold nanoparticles. Continuous reduction of Au (III) by Mb can be achieved by using hydroquinone as the reducing agent. The gold nanoparticles have been characterized by UV-visible spectroscopy. The formation and the surface plasmon resonance properties of the gold nanoparticles are highly dependent on the ratio of Au (III) to Mb in solution. X-ray photoelectron spectroscopy (XPS), fluorescence spectra and Fourier transform-infrared spectroscopy (FT-IR) spectra suggest that Mb molecules catalytically reduce Au (III) to Au (0) with the concomitant production of gold nanoparticles, and then, Mb statically adsorbed onto the surface of gold nanoparticles to form an Mb-gold nanoparticles assembly. This avoids secondary nucleation. The formed gold nanoparticles have been demonstrated to be monodispersed and uniform by transmission electron microscopy (TEM) images. Analysis of these particles shows an average size of 14.9 nm with a standard deviation of 1.1 nm. The gold nanoparticles are extremely stable and can resist aggregation, even after several months.
doi:10.3390/ijms141121676
PMCID: PMC3856028  PMID: 24189217
methanobactin; methanotrophs; gold nanoparticles; hydroquinone; monodisperse
25.  PRINT: A Novel Platform Toward Shape and Size Specific Nanoparticle Theranostics 
Accounts of chemical research  2011;44(10):990-998.
CONSPECTUS
Nanotheranostics represents the next generation of medicine, fusing nanotechnology, therapeutics, and diagnostics. By integrating therapeutic and imaging agents into one nanoparticle, this new treatment strategy has the potential not only to detect and diagnose disease but also to treat and monitor the therapeutic response. This capability could have a profound impact in both the research setting as well as in a clinical setting. In the research setting, such a capability will allow research scientists to rapidly assess the performance of new therapeutics in an effort to iterate their designs for increased therapeutic index and efficacy. In the clinical setting, theranostics offers the ability to determine whether patients enrolling in clinical trials are responding, or are expected to respond, to a given therapy based on the hypothesis associated with the biological mechanisms being tested. If not, patients can be more quickly removed from the clinical trial and shifted to other therapeutic options. To be effective, these theranostic agents must be highly site specific. Optimally, they will carry relevant cargo, demonstrate controlled release of that cargo, and include imaging probes with a high signal-to-noise ratio.
There are many biological barriers in the human body that challenge the efficacy of nanoparticle delivery vehicles. These barriers include, but are not limited to, the walls of blood vessels, the physical entrapment of particles in organs, and the removal of particles by phagocytic cells. The rapid clearance of circulating particles during systemic delivery is a major challenge; current research seeks to define key design parameters that govern the performance of nanocarriers, such as size, surface chemistry, elasticity, and shape. The effect of particle size and surface chemistry on in vivo biodistribution of nanocarriers has been extensively studied, and general guidelines have been established. Recently it has been documented that shape and elasticity can have a profound effect on the behavior of delivery vehicles. Thus, having the ability to independently control shape, size, matrix, surface chemistry, and modulus is crucial for designing successful delivery agents.
In this Account, we describe the use of particle replication in nonwetting templates (PRINT) to fabricate shape- and size-specific microparticles and nanoparticles. A particular strength of the PRINT method is that it affords precise control over shape, size, surface chemistry, and modulus. We have demonstrated the loading of PRINT particles with chemotherapeutics, magnetic resonance contrast agents, and fluorophores. The surface properties of the PRINT particles can be easily modified with “stealth” poly(ethylene glycol) chains to increase blood circulation time, with targeting moieties for targeted delivery or with radiolabels for nuclear imaging. These particles have tremendous potential for applications in nanomedicine and diagnostics.
doi:10.1021/ar2000315
PMCID: PMC4157651  PMID: 21809808

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