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author:("Wu, aiguë")
1.  Negatively Charged Metal Oxide Nanoparticles Interact with the 20S Proteasome and Differentially Modulate Its Biologic Functional Effects 
ACS nano  2013;7(9):7759-7772.
The multicatalytic ubiquitin-proteasome system (UPS) carries out proteolysis in a highly orchestrated way and regulates a large number of cellular processes. Deregulation of the UPS in many disorders has been documented. In some cases, e.g. carcinogenesis, elevated proteasome activity has been implicated in disease development, while the etiology of other diseases, e.g. neurodegeneration, includes decreased UPS activity. Therefore, agents that alter proteasome activity could suppress as well as enhance a multitude of diseases. Metal oxide nanoparticles, often developed as diagnostic tools, have not previously been tested as modulators of proteasome activity. Here, several types of metal oxide nanoparticles were found to adsorb to the proteasome and show variable preferential binding for particular proteasome subunits with several peptide binding “hotspots” possible. These interactions depend on the size, charge, and concentration of the nanoparticles and affect proteasome activity in a time-dependent manner. Should metal oxide nanoparticles increase proteasome activity in cells, as they do in vitro, unintended effects related to changes in proteasome function can be expected.
PMCID: PMC3946455  PMID: 23930940
iron oxide nanoparticles; titanium dioxide nanoparticles; protein adsorption; ubiquitin-proteasome system; proteasome activation
2.  Exercise facilitates the action of dietary DHA on functional recovery after brain trauma 
Neuroscience  2013;248:655-663.
The abilities of docosahexaenoic acid (DHA) and exercise to counteract cognitive decay after TBI is getting increasing recognition; however, the possibility that these actions can be complementary remains just as an intriguing possibility. Here we have examined the likelihood that the combination of diet and exercise has the added potential to facilitate functional recovery following TBI. Rats received mild fluid percussion injury (mFPI) or sham injury and then were maintained on a diet high in DHA (1.2% DHA) with or without voluntary exercise for 12 days. We found that FPI reduced DHA content in the brain, which was accompanied by increased levels of lipid peroxidation assessed using 4-HHE. FPI reduced the enzymes Acox1 and 17 -HSD4, and the calcium-independent phospholipases A2 (iPLA2), which are involved in metabolism of membrane phospholipids. FPI reduced levels of syntaxin-3 (STX-3), involved in the action of membrane DHA on synaptic membrane expansion, and also reduced BDNF signaling through its TrkB receptor. These effects of FPI were optimally counteracted by the combination of DHA and exercise. Our results support the possibility that the complementary action of exercise is exerted on restoring membrane homeostasis after TBI, which is necessary for supporting synaptic plasticity and cognition. It is our contention that strategies that take advantage of the combined applications of diet and exercise may have additional effects to the injured brain.
PMCID: PMC3951948  PMID: 23811071
DHA; exercise; BDNF; omega-3 fatty acids; cognition
3.  The latest progress in research on triple negative breast cancer (TNBC): risk factors, possible therapeutic targets and prognostic markers 
Journal of Thoracic Disease  2014;6(9):1329-1335.
Triple negative breast cancer (TNBC) is one type of breast cancer (BC), which is defined as negative for estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (Her2). Its origins and development seem to be elusive. And for now, drugs like tamoxifen or trastuzumab which specifically apply to ER, PR or Her2 positive BC seem unforeseeable in TNBC clinical treatment. Due to its extreme malignancy, high recurrence rate and poor prognosis, a lot of work on the research of TNBC is needed. This review aims to summarize the latest findings in TNBC in risk factors, possible therapeutic targets and possible prognostic makers.
PMCID: PMC4178098  PMID: 25276378
Triple negative breast cancer (TNBC); risk factor; therapeutic target; prognostic marker
4.  A Multimodal Nanocomposite for Biomedical Imaging 
AIP conference proceedings  2011;1365:379-.
A multimodal nanocomposite was designed, synthesized with super-paramagnetic core (CoFe2O4), noble metal corona (Au), and semiconductor shell (TiO2). The sizes of core, core-corona, and core-corona-shell particles were determined by TEM. This multimodal nanocrystal showed promise as a contrast agent for two of the most widely used biomedical imaging techniques: magnetic resonance imaging (MRI) and X-ray computed tomography (CT). Finally, these nanocomposites were coated with a peptide SN-50. This led to their ready uptake by the cultured cells and targeted the nanocomposites to the pores of nuclear membrane. Inside cells, this nanocomposite retained its integrity as shown by X-ray fluorescence microscopy (XFM). Inside cells imaged by XFM we found the complex elemental signature of nanoconjugates (Ti-Co-Fe-Au) always co-registered in the 2D elemental map of the cell.
PMCID: PMC4012782  PMID: 24817775
multimodal nanoconjugate; Magnetic Resonance Imaging; X-ray Computed Tomography; X-ray fluorescence microscopy
5.  Dietary therapy to promote neuroprotection in chronic spinal cord injury 
Journal of neurosurgery. Spine  2012;17(2):134-140.
The pathogenesis of cervical spondylotic myelopathy (CSM) is related to both primary mechanical and secondary biological injury. The authors of this study explored a novel, noninvasive method of promoting neuroprotection in myelopathy by using curcumin to minimize oxidative cellular injury and the capacity of omega-3 fatty acids to support membrane structure and improve neurotransmission.
An animal model of CSM was created using a nonresorbable expandable polymer placed in the thoracic epidural space, which induced delayed myelopathy. Animals that underwent placement of the expandable polymer were exposed to either a diet rich in docosahexaenoic acid and curcumin (DHA-Cur) or a standard Western diet (WD). Twenty-seven animals underwent serial gait testing, and spinal cord molecular assessments were performed after the 6-week study period.
At the conclusion of the study period, gait analysis revealed significantly worse function in the WD group than in the DHA-Cur group. Levels of brain-derived neurotrophic factor (BDNF), syntaxin-3, and 4-hydroxynonenal (4-HNE) were measured in the thoracic region affected by compression and lumbar enlargement. Results showed that BDNF levels in the DHA-Cur group were not significantly different from those in the intact animals but were significantly greater than in the WD group. Significantly higher lumbar enlargement syntaxin-3 in the DHA-Cur animals combined with a reduction in lipid peroxidation (4-HNE) indicated a possible healing effect on the plasma membrane.
Data in this study demonstrated that DHA-Cur can promote spinal cord neuroprotection and neutralize the clinical and biochemical effects of myelopathy.
PMCID: PMC3951955  PMID: 22735048
myelopathy; docosahexaenoic acid; curcumin; membrane; spinal cord injury; rat
6.  Acute toxicity of nickel nanoparticles in rats after intravenous injection 
This study was carried out to add scientific data in regard to the use of metallic nanoparticles in nanomedicine. The acute toxicity of nickel (Ni) nanoparticles (50 nm), intravenously injected through the dorsal penile vein of Sprague Dawley rats was evaluated in this study. Fourteen days after injection, Ni nanoparticles induced liver and spleen injury, lung inflammation, and caused cardiac toxicity. These results indicate that precautionary measures should be taken with regard to the use of Ni nanoparticles or Ni compounds in nanomedicine.
PMCID: PMC3958504  PMID: 24648736
nickel; nanoparticles; intravenous; acute toxicity
7.  A young woman with a giant breast fibrosarcoma: a case report 
Journal of Thoracic Disease  2013;5(5):E199-E202.
We report a case of a 15-year-old female, no family history of huge fibrosarcoma. Computed tomography (CT) showed that there was no clearance between the lump and pectoralis major and that there were pathological fractures in the third and fourth ribs. Fine-needle aspiration result suggested that it might be a phyllodes tumor of the breast. According to the postoperative pathologic and immunohistochemical results, the final diagnosis was breast fibrosarcoma.
PMCID: PMC3815730  PMID: 24255792
Breast fibrosarcoma; diagnosis; synovial sarcoma; treatment
8.  Acute Toxicity of Intravenously Administered Titanium Dioxide Nanoparticles in Mice 
PLoS ONE  2013;8(8):e70618.
With a wide range of applications, titanium dioxide (TiO2) nanoparticles (NPs) are manufactured worldwide in large quantities. Recently, in the field of nanomedicine, intravenous injection of TiO2 nanoparticulate carriers directly into the bloodstream has raised public concerns on their toxicity to humans.
In this study, mice were injected intravenously with a single dose of TiO2 NPs at varying dose levels (0, 140, 300, 645, or 1387 mg/kg). Animal mortality, blood biochemistry, hematology, genotoxicity and histopathology were investigated 14 days after treatment.
Death of mice in the highest dose (1387 mg/kg) group was observed at day two after TiO2 NPs injection. At day 7, acute toxicity symptoms, such as decreased physical activity and decreased intake of food and water, were observed in the highest dose group. Hematological analysis and the micronucleus test showed no significant acute hematological or genetic toxicity except an increase in the white blood cell (WBC) count among mice 645 mg/kg dose group. However, the spleen of the mice showed significantly higher tissue weight/body weight (BW) coefficients, and lower liver and kidney coefficients in the TiO2 NPs treated mice compared to control. The biochemical parameters and histological tissue sections indicated that TiO2 NPs treatment could induce different degrees of damage in the brain, lung, spleen, liver and kidneys. However, no pathological effects were observed in the heart in TiO2 NPs treated mice.
Intravenous injection of TiO2 NPs at high doses in mice could cause acute toxicity effects in the brain, lung, spleen, liver, and kidney. No significant hematological or genetic toxicity was observed.
PMCID: PMC3738549  PMID: 23950972
9.  Synthesis and Characterization of Fe10BO3/Fe3O4/SiO2 and GdFeO3/Fe3O4/SiO2: Nanocomposites of Biofunctional Materials 
ChemistryOpen  2013;2(3):88-92.
PMCID: PMC3703812  PMID: 24551544
biofunctional materials; gel combustion techniques; nanocomposites; neutron capture therapy
10.  Nanocarriers Enhance Doxorubicin Uptake in Drug-Resistant Ovarian Cancer Cells 
Cancer research  2011;72(3):769-778.
Resistance to anthracyclines and other chemotherapeutics due to P-glycoprotein (PGP)-mediated export is a frequent problem in cancer treatment. Here we report that iron oxide-titanium dioxide core-shell nanocomposites can serve as efficient carriers for doxorubicin to overcome this common mechanism of drug resistance in cancer cells. Doxorubicin nanocarriers (DNCs) increased effective drug uptake in drug-resistant ovarian cells. Mechanistically, doxorubicin bound to the TiO2 surface by a labile bond that was severed upon acidification within cell endosomes. Upon its release doxorubicin traversed the intracellular milieu and entered the cell nucleus by a route that evaded PGP-mediated drug export. Confocal and x-ray fluorescence microscopy with flow cytometry were used to demonstrate the ability of DNC to modulate transferrin uptake and distribution in cells. Increased transferrin uptake occurred through clathrin-mediated endocytosis, indicating that nanocomposites and DNCs may both interfere with removal of transferrin from cells. Together, our findings show that DNCs not only provide an alternative route of delivery of doxorubicin to PGP-over-expressing cancer cells, but may also boost the uptake of transferrin-tagged therapeutic agents.
PMCID: PMC3657469  PMID: 22158944
doxorubicin; nanocarrier; titanium dioxide; endocytosis; transferrin
11.  The Salutary Effects of DHA Dietary Supplementation on Cognition, Neuroplasticity, and Membrane Homeostasis after Brain Trauma 
Journal of Neurotrauma  2011;28(10):2113-2122.
The pathology of traumatic brain injury (TBI) is characterized by the decreased capacity of neurons to metabolize energy and sustain synaptic function, likely resulting in cognitive and emotional disorders. Based on the broad nature of the pathology, we have assessed the potential of the omega-3 fatty acid docosahexaenoic acid (DHA) to counteract the effects of concussive injury on important aspects of neuronal function and cognition. Fluid percussion injury (FPI) or sham injury was performed, and rats were then maintained on a diet high in DHA (1.2% DHA) for 12 days. We found that DHA supplementation, which elevates brain DHA content, normalized levels of brain-derived neurotrophic factor (BDNF), synapsin I (Syn-1), cAMP-responsive element-binding protein (CREB), and calcium/calmodulin-dependent kinase II (CaMKII), and improved learning ability in FPI rats. It is known that BDNF facilitates synaptic transmission and learning ability by modulating Syn-I, CREB, and CaMKII signaling. The DHA diet also counteracted the FPI-reduced manganese superoxide dismutase (SOD) and Sir2 (a NAD+-dependent deacetylase). Given the involvement of SOD and Sir2 in promoting metabolic homeostasis, DHA may help the injured brain by providing resistance to oxidative stress. Furthermore, DHA normalized levels of calcium-independent phospholipase A2 (iPLA2) and syntaxin-3, which may help preserve membrane homeostasis and function after FPI. The overall results emphasize the potential of dietary DHA to counteract broad and fundamental aspects of TBI pathology that may translate into preserved cognitive capacity.
PMCID: PMC3191367  PMID: 21851229
brain-derived neurotrophic factor; plasticity; Sir2; superoxide dismutase; traumatic brain injury
12.  Effects of Diet and/or Exercise in Enhancing Spinal Cord Sensorimotor Learning 
PLoS ONE  2012;7(7):e41288.
Given that the spinal cord is capable of learning sensorimotor tasks and that dietary interventions can influence learning involving supraspinal centers, we asked whether the presence of omega-3 fatty acid docosahexaenoic acid (DHA) and the curry spice curcumin (Cur) by themselves or in combination with voluntary exercise could affect spinal cord learning in adult spinal mice. Using an instrumental learning paradigm to assess spinal learning we observed that mice fed a diet containing DHA/Cur performed better in the spinal learning paradigm than mice fed a diet deficient in DHA/Cur. The enhanced performance was accompanied by increases in the mRNA levels of molecular markers of learning, i.e., BDNF, CREB, CaMKII, and syntaxin 3. Concurrent exposure to exercise was complementary to the dietary treatment effects on spinal learning. The diet containing DHA/Cur resulted in higher levels of DHA and lower levels of omega-6 fatty acid arachidonic acid (AA) in the spinal cord than the diet deficient in DHA/Cur. The level of spinal learning was inversely related to the ratio of AA∶DHA. These results emphasize the capacity of select dietary factors and exercise to foster spinal cord learning. Given the non-invasiveness and safety of the modulation of diet and exercise, these interventions should be considered in light of their potential to enhance relearning of sensorimotor tasks during rehabilitative training paradigms after a spinal cord injury.
PMCID: PMC3401098  PMID: 22911773
13.  Endocytosis of Titanium Dioxide Nanoparticles in Prostate Cancer PC-3M Cells 
Nanotechnology has introduced many exciting new tools for the treatment of human diseases. One of the obstacles in its application to that end is the lack of a fundamental understanding of the interaction that occurs between nanoparticles and living cells. This report describes the quantitative analysis of the kinetics and endocytic pathways involved in the uptake of anatase titanium dioxide (TiO2) nanoparticles into prostate cancer PC-3M cells. The experiments were performed with TiO2 nanoconjugates—6 nm nanoparticles with surface conjugated fluorescent Alizarin Red S (ARS). Results obtained by flow cytometry, fluorescence microscopy, and inductively-coupled plasma mass spectrometry confirmed a complex nanoparticle-cell interaction involving a variety of endocytic mechanisms. The results demonstrated that a temperature, concentration, and time-dependent internalization of the TiO2 nanoparticles and nanoconjugates occurred via clathrin-mediated endocytosis, caveolin-mediated endocytosis, and macropinocytosis.
PMCID: PMC3062699  PMID: 20887814
anatase; TiO2; nanoconjugate; endocytosis; Alizarin Red S
14.  Brain and Spinal Cord Interaction: A Dietary Curcumin Derivative Counteracts Locomotor and Cognitive Deficits After Brain Trauma 
In addition to cognitive dysfunction, locomotor deficits are prevalent in traumatic brain injured (TBI) patients; however, it is unclear how a concussive injury can affect spinal cord centers. Moreover, there are no current efficient treatments that can counteract the broad pathology associated with TBI.
The authors have investigated potential molecular basis for the disruptive effects of TBI on spinal cord and hippocampus and the neuroprotection of a curcumin derivative to reduce the effects of experimental TBI.
The authors performed fluid percussion injury (FPI) and then rats were exposed to dietary supplementation of the curcumin derivative (CNB-001; 500 ppm). The curry spice curcumin has protective capacity in animal models of neurodegenerative diseases, and the curcumin derivative has enhanced brain absorption and biological activity.
The results show that FPI in rats, in addition to reducing learning ability, reduced locomotor performance. Behavioral deficits were accompanied by reductions in molecular systems important for synaptic plasticity underlying behavioral plasticity in the brain and spinal cord. The post-TBI dietary supplementation of the curcumin derivative normalized levels of BDNF, and its downstream effectors on synaptic plasticity (CREB, synapsin I) and neuronal signaling (CaMKII), as well as levels of oxidative stress–related molecules (SOD, Sir2).
These studies define a mechanism by which TBI can compromise centers related to cognitive processing and locomotion. The findings also show the influence of the curcumin derivative on synaptic plasticity events in the brain and spinal cord and emphasize the therapeutic potential of this noninvasive dietary intervention for TBI.
PMCID: PMC3258099  PMID: 21343524
traumatic brain injury; hippocampus; learning; BDNF; curcumin derivative
15.  DHA dietary supplementation enhances the effects of exercise on synaptic plasticity and cognition 
Neuroscience  2008;155(3):751-759.
Omega-3 fatty acids (i.e., docosahexaenoic acid; DHA), similar to exercise, improve cognitive function, promote neuroplasticity, and protect against neurological lesion. In this study, we investigated a possible synergistic action between DHA dietary supplementation and voluntary exercise on modulating synaptic plasticity and cognition. Rats received DHA dietary supplementation (1.25% DHA) with or without voluntary exercise for 12 days. We found that the DHA-enriched diet significantly increased spatial learning ability, and these effects were enhanced by exercise. The DHA-enriched diet increased levels of pro-BDNF and mature BDNF, whereas the additional application of exercise boosted the levels of both. Furthermore, the levels of the activated forms of CREB and synapsin I were incremented by the DHA-enriched diet with greater elevation by the concurrent application of exercise. While the DHA diet reduced hippocampal oxidized protein levels, a combination of a DHA diet and exercise resulted in a greater reduction rate. The levels of activated forms of hippocampal Akt and CaMKII were increased by the DHA-enriched diet, and with even greater elevation by a combination of diet and exercise. Akt and CaMKII signaling are crucial step by which BDNF exerts its action on synaptic plasticity and learning and memory. These results indicate that the DHA diet enhance the effects of exercise on cognition and BDNF-related synaptic plasticity, a capacity that may be used to promote mental health and reduce risk of neurological disorders.
PMCID: PMC3208643  PMID: 18620024
DHA; exercise; BDNF; omega-3 fatty acids; cognition
17.  Vitamin E Protects Against Oxidative Damage and Learning Disability After Mild Traumatic Brain Injury in Rats 
Reactive oxygen species induce neuronal damage, and their role in reducing synaptic plasticity and function is beginning to be understood. Vitamin E is a potent reactive oxygen species scavenger, which has the potential to reduce oxidative damage encountered after traumatic brain injury (TBI). Brain-derived neurotrophic factor (BDNF) can facilitate synaptic function and support learning by modulating the CaMKII system, synapsin I, and cAMP-response element-binding protein (CREB). The elevation of superoxide dismutase (SOD) and Sir2 (silent information regulator 2) play an important role in resistance to oxidative stress.
We examined the possibility that vitamin E supplemented in the diet may help counteract the effects of TBI on the molecular substrates underlying synaptic plasticity and cognitive function in the hippocampus.
Rats were fed a regular diet with or without 500 IU/kg of vitamin E for 4 weeks (n = 6-8 per group) before a mild fluid percussion injury (FPI) was performed.
FPI increased protein oxidation as evidenced by elevated levels of protein carbonyls and reduced levels of SOD and Sir2. In addition, FPI resulted in poor performance in the Morris water maze, which was accompanied by reduced levels of BDNF and its downstream effectors on synaptic plasticity, synapsin I, CREB, and CaMKII. Supplementation of vitamin E in the diet counteracted all the observed effects of FPI.
These results suggest that vitamin E dietary supplementation can protect the brain against the effects of mild TBI on synaptic plasticity and cognition, using molecular systems associated with the maintenance of long-term plasticity, such as BDNF and Sir2.
PMCID: PMC2824788  PMID: 19841436
traumatic brain injury; hippocampus; learning; BDNF; vitamin E
18.  Methods for assessing DNA hybridization of PNA-TiO2 nanoconjugates 
Analytical biochemistry  2008;383(2):226-235.
We describe the synthesis of peptide nucleic acid (PNA)-titanium dioxide (TiO2) nanoconjugates and the several novel methods developed to investigate the DNA hybridization behaviors of these constructs. PNAs are synthetic DNA analogs resistant to degradation by cellular enzymes, which hybridize to single strand DNA (ssDNA) with higher affinity than DNA oligonucleotides, invade double strand DNA (dsDNA), and form different PNA-DNA complexes. Previously, we developed a DNA-TiO2 nanoconjugate capable of hybridizing to target DNA intracellularly in a sequence-specific manner, with the ability to cleave DNA when excited by electromagnetic radiation, but susceptible to degradation which may lower its intracellular targeting efficiency and retention time. PNA-TiO2 nanoconjugates described herein hybridize to target ssDNA, oligonucleotide dsDNA, and supercoiled plasmid DNA under physiological-like ionic and temperature conditions, enabling rapid and inexpensive, sequence-specific precipitation of nucleic acids in vitro. When modified by the addition of imaging agents or peptides, hybridization capabilities of PNA-TiO2 nanoconjugates are enhanced which provides essential benefits for numerous in vitro and in vivo applications. The series of experiments shown here could not be done with either TiO2-DNA nanoconjugates or PNAs alone, and the novel methods developed will benefit studies of numerous other nanoconjugate systems.
PMCID: PMC2597192  PMID: 18786502
titanium dioxide; peptide nucleic acid; nanoparticle; DNA; hybridization
19.  Labeling TiO2 Nanoparticles with Dyes for Optical Fluorescence Microscopy and Determination of TiO2-DNA Nanoconjugate Stability 
Visualization of nanoparticles without intrinsic optical fluorescence properties is a significant problem when performing intracellular studies. Such is the case with titanium dioxide (TiO2) nanoparticles. These nanoparticles, when electronically linked to single stranded DNA oligonucleotides, have been proposed to be used both as gene knockout devices and as possible tumor imaging agents. By interacting with complementary target sequences in living cells, these photo-inducible TiO2-DNA nanoconjugates have the potential to cleave intracellular genomic DNA in a sequence specific and inducible manner. The nanoconjugates also become detectable by magnetic resonance imaging (MRI) with the addition of gadolinium Gd(III) contrast agents. Herein we describe two approaches for labeling TiO2 nanoparticles and TiO2-DNA nanoconjugates with optically fluorescent agents. This permits, for the first time, direct quantification of fluorescently labeled TiO2 nanoparticle uptake in a large population of living cells (>104 cells). X-Ray Fluorescence Microscopy (XFM) was combined with fluorescent microscopy to determine the relative intracellular stability of the nanoconjugates. It was also used to quantify intracellular nanoparticles. Imaging the DNA component of the TiO2-DNA nanoconjugate by fluorescent confocal microscopy within the same cell showed an overlap with the titanium signal as mapped by XFM. This strongly implies the intracellular integrity of the TiO2-DNA nanoconjugates in malignant cells.
PMCID: PMC2787618  PMID: 19242946
TiO2-DNA Nanoconjugate; Nanoparticle; X-Ray Fluorescence Microscopy; Titanium Dioxide
20.  Titantium Dioxide Nanoparticles Assembled by DNA Molecules Hybridization and Loading of DNA Interacting Proteins 
Nano  2008;3(1):27-36.
This work demonstrates the assembly of TiO2 nanoparticles with attached DNA oligonucleotides into a 3D mesh structure by allowing base pairing between oligonucleotides. A change of the ratio of DNA oligonucleotide molecules and TiO2 nanoparticles regulates the size of the mesh as characterized by UV-visible light spectra, transmission electron microscopy and atomic force microscopy images. This type of 3D mesh, based on TiO2-DNA oligonucleotide nanoconjugates, can be used for studies of nanoparticle assemblies in material science, energy science related to dye-sensitized solar cells, environmental science as well as characterization of DNA interacting proteins in the field of molecular biology. As an example of one such assembly, proliferating cell nuclear antigen protein (PCNA) was cloned, its activity verified, and the protein was purified, loaded onto double strand DNA oligonucleotide-TiO2 nanoconjugates, and imaged by atomic force microscopy. This type of approach may be used to sample and perhaps quantify and/or extract specific cellular proteins from complex cellular protein mixtures affinity based on their affinity for chosen DNA segments assembled into the 3D matrix.
PMCID: PMC2772173  PMID: 19890457
Titanium dioxide nanoparticles; DNA; PCNA protein; atomic force microscopy; transmission electron microscopy; assembly; agarose; nanoconjugate
21.  Gadolinium conjugated TiO2-DNA oligonucleotide nanoconjugates show prolonged intracellular retention period and T1-weighted contrast enhancement in Magnetic Resonance images 
Nanoconjugates composed of TiO2 nanoparticles, DNA oligonucleotides and a gadolinium contrast agent were synthesized for use in magnetic resonance imaging. Transfection of cultured cancer cells with these nanoconjugates showed them to be superior to the free contrast agent of same formulation with regard to 1) intracellular accumulation, 2) retention and 3) subcellular localization. Our results have shown that 48 hours after treatment, the concentration of gadolinium in nanoconjugate treated cells was 1000 fold higher compared to cells treated with contrast agent alone. Consequently, T1-weighted contrast enhancements were observed in cells treated with nanoconjugates but not in cells treated by the contrast agent alone. This type of nanoconjugate with increased retention time, Gd accumulation and intracellular delivery may find its use in gadolinium neutron-capture cancer therapy.
PMCID: PMC2663023  PMID: 18567541
nanoconjugates; magnetic resonance imaging; subcellular targeting
22.  Nanoparticles for Applications in Cellular Imaging 
Nanoscale Research Letters  2007;2(9):430-441.
In the following review we discuss several types of nanoparticles (such as TiO2, quantum dots, and gold nanoparticles) and their impact on the ability to image biological components in fixed cells. The review also discusses factors influencing nanoparticle imaging and uptake in live cells in vitro. Due to their unique size-dependent properties nanoparticles offer numerous advantages over traditional dyes and proteins. For example, the photostability, narrow emission peak, and ability to rationally modify both the size and surface chemistry of Quantum Dots allow for simultaneous analyses of multiple targets within the same cell. On the other hand, the surface characteristics of nanometer sized TiO2allow efficient conjugation to nucleic acids which enables their retention in specific subcellular compartments. We discuss cellular uptake mechanisms for the internalization of nanoparticles and studies showing the influence of nanoparticle size and charge and the cell type targeted on nanoparticle uptake. The predominant nanoparticle uptake mechanisms include clathrin-dependent mechanisms, macropinocytosis, and phagocytosis.
PMCID: PMC3246594  PMID: 21794189
Nanoparticle; Cellular uptake; Quantum dots; Titanium dioxide

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