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1.  In vitro and in vivo evaluation of ordered mesoporous silica as a novel adsorbent in liquisolid formulation 
Background
A liquisolid technique has been reported to be a new approach to improve the release of poorly water-soluble drugs for oral administration. However, an apparent limitation of this technique is the formulation of a high dose because a large amount of liquid vehicle is needed, which finally results in a low-dose liquisolid formulation. Silica as an absorbent has been used extensively in liquisolid formulations. Although nanoparticle silica can be prepared and used to improve liquid adsorption capacity, loading a high dose of drug into a liquisolid is still a challenge. With the aim of improving adsorption capacity and accordingly achieving high drug loading, ordered mesoporous silica with a high surface area and narrow pore size distribution was synthesized and used in a liquisolid formulation.
Methods
Ordered mesoporous silica was synthesized and its particle size and morphology were tailored by controlling the concentration of cetyltrimethyl ammonium bromide. The ordered mesoporous silica synthesized was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, small-angle x-ray diffraction, wide angle x-ray diffraction, and nitrogen adsorption-desorption measurements. The liquid adsorption capacity of ordered mesoporous silica was subsequently compared with that of conventional silica materials using PEG400 as the model liquid. Carbamazepine was chosen as a model drug to prepare the liquisolid formulation, with ordered mesoporous silica as the adsorbent material. The preparation was evaluated and compared with commercially available fast-release carbamazepine tablets in vitro and in vivo.
Results
Characterization of the ordered mesoporous silica synthesized in this study indicated a huge Brunauer–Emmett–Teller surface area (1030 m2/g), an ordered mesoporous structure with a pore size of 2.8 nm, and high adsorption capacity for liquid compared with conventional silica. Compared with fast-release commercial carbamazepine tablets, drug release from the liquisolid capsules was greatly improved, and the bioavailability of the liquisolid preparation was enhanced by 182.7%.
Conclusion
Ordered mesoporous silica is a potentially attractive adsorbent which may lead to a new approach for development of liquisolid products.
doi:10.2147/IJN.S26763
PMCID: PMC3263412  PMID: 22275835
ordered mesoporous silica; poorly water-soluble drug; carbamazepine; liquisolid; bioavailability
2.  Comparative Analysis of the Conventional and Novel pmo (Particulate Methane Monooxygenase) Operons from Methylocystis Strain SC2 
In addition to the conventional pmoA gene (pmoA1) encoding the active site polypeptide of particulate methane monooxygenase, a novel pmoA gene copy (pmoA2) is widely distributed among type II methanotrophs (methane-oxidizing bacteria [MOB]) (M. Tchawa Yimga, P. F. Dunfield, P. Ricke, J. Heyer, and W. Liesack, Appl. Environ. Microbiol. 69:5593-5602, 2003). Here we report that the pmoA1 and pmoA2 gene copies in the type II MOB Methylocystis strain SC2 are each part of a complete pmoCAB gene cluster (pmoCAB1, pmoCAB2). A bacterial artificial chromosome (BAC) library of strain SC2 genomic DNA was constructed, and BAC clones carrying either pmoCAB1 or pmoCAB2 were identified. Comparative sequence analysis showed that these two gene clusters exhibit low levels of identity at both the DNA level (67.4 to 70.9%) and the derived protein level (59.3 to 65.6%). In contrast, the secondary structures predicted for PmoCAB1 and PmoCAB2, as well as the derived transmembrane-spanning regions, are nearly identical. This suggests that PmoCAB2 is, like PmoCAB1, a highly hydrophobic, membrane-associated protein. A total of 190 of the 203 amino acid residues representing a highly conserved consensus sequence of the currently known PmoCAB1 and AmoCAB sequence types could be identified in PmoCAB2. The amoCAB gene cluster encodes ammonia monooxygenase and is evolutionarily related to pmoCAB. Analysis of a set of amino acid residues that allowed differentiation between conventional PmoA and AmoA provided further support for the hypothesis that pmoCAB2 encodes a functional equivalent of PmoCAB1. In experiments in which we used 5′ rapid amplification of cDNA ends we identified transcriptional start sites 320 and 177 bp upstream of pmoC1 and pmoC2, respectively. Immediately upstream of the transcriptional start sites of both pmoCAB1 and pmoCAB2, sequence motifs similar to Escherichia coli σ70 promoters were identified.
doi:10.1128/AEM.70.5.3055-3063.2004
PMCID: PMC404415  PMID: 15128567
3.  Inorganic–organic hybrid materials through post-synthesis modification: Impact of the treatment with azides on the mesopore structure 
Summary
Hybrid, hierarchically organized, monolithic silica gels, comprising periodically arranged mesopores and a cellular macroscopic network, have been prepared through a co-condensation reaction of tetrakis(2-hydroxyethyl)orthosilicate with chloromethyl-trimethoxysilane or 3-(chloropropyl)-triethoxysilane. Subsequent conversion of the chloro groups into azido groups, by nucleophilic substitution with NaN3 in N,N-dimethylformamide, was conducted upon preservation of the monolithic structure. However, treatment with NaN3 had a strong influence on the structure in the mesoporous regime, with changes such as an increase of mesopore diameter, pore volume and lattice constants, as well as a concomitant decrease of the pore wall thickness, as confirmed by small angle X-ray scattering, transmission electron microscopy, and nitrogen sorption analysis. Similar effects were observed for unmodified silica gels by simple ageing in azide-containing media, whether a relatively small or a sterically demanding counter ion (Na+ or (H3C)4N+) was used. The structural modification did not seem to depend greatly on whether an organic aprotic solvent (N,N-dimethylformamide, 1,1,3,3-tetramethylurea, 1,3-dimethyl-2-imidazolidinone) or a protic solvent that can form hydrogen bonds, such as water, was used.
doi:10.3762/bjnano.2.52
PMCID: PMC3190618  PMID: 22003454
inorganic–organic hybrid materials; mesoporous materials; nucleophilic substitution; silica; sol–gel chemistry
4.  Indoor formaldehyde removal over CMK-3 
The removal of formaldehyde at low concentrations is important in indoor air pollution research. In this study, mesoporous carbon with a large specific surface area was used for the adsorption of low-concentration indoor formaldehyde. A mesoporous carbon material, CMK-3, was synthesized using the nano-replication method. SBA-15 was used as a mesoporous template. The surface of CMK-3 was activated using a 2N H2SO4 solution and NH3 gas to prepare CMK-3-H2SO4 and CMK-3-NH3, respectively. The activated samples were characterized by N2 adsorption-desorption, X-ray diffraction, and X-ray photoelectron spectroscopy. The formaldehyde adsorption performance of the mesoporous carbons was in the order of CMK-3-NH3 > CMK-3-H2SO4 > CMK-3. The difference in the adsorption performance was explained by oxygen and nitrogen functional groups formed during the activation process and by the specific surface area and pore structure of mesoporous carbon.
doi:10.1186/1556-276X-7-7
PMCID: PMC3271978  PMID: 22221425
low-concentration formaldehyde; mesoporous carbon; sulfuric acid; ammonia; activation; adsorption
5.  Periodic Mesoporous Organosilica Nanorice 
Nanoscale Research Letters  2008;4(2):169-172.
A periodic mesoporous organosilica (PMO) with nanorice morphology was successfully synthesized by a template assisted sol–gel method using a chain-type precursor. The PMO is composed of D and T sites in the ratio 1:2. The obtained mesoporous nanorice has a surface area of 753 m2 g−1, one-dimensional channels, and a narrow pore size distribution centered at 4.3 nm. The nanorice particles have a length of ca. 600 nm and width of ca. 200 nm.
doi:10.1007/s11671-008-9219-0
PMCID: PMC2894019  PMID: 20596415
Nanorice; Mesoporous materials; Periodic mesoporous organosilica
6.  Periodic Mesoporous Organosilica Nanorice 
Nanoscale Research Letters  2008;4(2):169-172.
A periodic mesoporous organosilica (PMO) with nanorice morphology was successfully synthesized by a template assisted sol–gel method using a chain-type precursor. The PMO is composed of D and T sites in the ratio 1:2. The obtained mesoporous nanorice has a surface area of 753 m2 g−1, one-dimensional channels, and a narrow pore size distribution centered at 4.3 nm. The nanorice particles have a length of ca. 600 nm and width of ca. 200 nm.
doi:10.1007/s11671-008-9219-0
PMCID: PMC2894019  PMID: 20596415
Nanorice; Mesoporous materials; Periodic mesoporous organosilica
7.  A combination of hard and soft templating for the fabrication of silica hollow microcoils with nanostructured walls 
Nanoscale Research Letters  2011;6(1):330.
Hollow silica microcoils have been prepared by using functionalized carbon microcoils as hard templates and surfactant or amphiphilic dye aggregates as soft templates. The obtained materials have been characterized by electron and optical microscopy, nitrogen sorption and small angle X-ray scattering. The obtained hollow microcoils resemble the original hard templates in shape and size. Moreover, they have mesoporous walls (pore size ≈ 3 nm) with some domains where pores are ordered in a hexagonal array, originated from surfactant micelles. The obtained silica microcoils also show preferential adsorption of cationic fluorescent dyes. A mechanism for the formation of silica microcoils is proposed.
doi:10.1186/1556-276X-6-330
PMCID: PMC3211418  PMID: 21711843
8.  Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: an Expanding Shell Model of Monomer Distribution 
Hydrophobic monomers partially phase-separate from saturated lipids when loaded into lipid bilayers in amounts exceeding 1:1 monomer:lipid molar ratio. This conclusion is based on agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in increase in bilayer thickness and slight increase in the diameter of liposomes. Homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to the increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small angle neutron scattering (SANS) and small angle X-ray scattering (SAXS), was approximately one half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was in the middle between values predicted for homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at 1.2 monomer:lipid ratio, approximately one half of monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for directed covalent assembly of organic nanomaterials. In particular, partial phase separation of monomers from lipids corroborates successful creation of nanometer-thin polymer materials with uniform imprinted nanopores. Pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.
doi:10.1021/la1050942
PMCID: PMC3097174  PMID: 21391646
9.  Porosity and Surface Properites of SBA-15 with Grafted PNIPAAM: A Water Sorption Calorimetry Study 
Langmuir  2011;27(22):13838-13846.
Mesoporous silica SBA-15 was modified in a three-step process to obtain a material with poly-N-isopropylacrylamide (PNIPAAM) grafted onto the inner pore surface. Water sorption calorimetry was implemented to characterize the materials obtained after each step regarding the porosity and surface properties. The modification process was carried out by (i) increasing the number of surface silanol groups, (ii) grafting 1-(trichlorosilyl)-2-(m-/p-(chloromethylphenyl) ethane, acting as an anchor for (iii) the polymerization of N-isopropylacrylamide. Water sorption isotherms and the enthalpy of hydration are presented. Pore size distributions were calculated on the basis of the water sorption isotherms by applying the BJH model. Complementary measurements with nitrogen sorption and small-angle X-ray diffraction are presented. The increase in the number of surface silanol groups occurs mainly in the intrawall pores, the anchor is mainly located in the intrawall pores, and the intrawall pore volume is absent after the surface grafting of PNIPAAM. Hence, PNIPAAM seals off the intrawall pores. Water sorption isotherms directly detect the presence of intrawall porosity. Pore size distributions can be calculated from the isotherms. Furthermore, the technique provides information regarding the hydration capability (i.e., wettability of different chemical surfaces) and thermodynamic information.
doi:10.1021/la203093u
PMCID: PMC3324985  PMID: 21928772
10.  Sld2 binds to origin single-stranded DNA and stimulates DNA annealing 
Nucleic Acids Research  2010;39(7):2580-2592.
Sld2 is essential for the initiation of DNA replication, but the mechanism underlying its role in replication is not fully understood. The S-phase cyclin dependent kinase (S-CDK) triggers the association of Sld2 with Dpb11, and a phosphomimetic mutation of Sld2, Sld2T84D, functionally mimics the S-CDK phosphorylated state of Sld2. We report that Sld2T84D binds directly to the single-stranded (ss) DNA of two different origins of replication, and S-CDK phosphorylation of Sld2 stimulates the binding of Sld2 to origin ssDNA. Sld2T84D binds to a thymine-rich ssDNA region of the origin ARS1, and substitution of ARS1 thymines with adenines completely disrupts binding of Sld2T84D. Sld2T84D enhances the ability of origin ssDNA to pulldown Dpb11, and Sld2 binding to origin ssDNA may be important to allow Sld2 and Dpb11 to associate with origin DNA. We also report that Sld2T84D anneals ssDNA of an origin sequence. Dpb11 anneals ssDNA to low levels, and the addition of Sld2T84D with Dpb11 results in higher annealing activity than that of either protein alone. Sld2-stimulated annealing may be important for maintaining genome stability during the initiation of DNA replication.
doi:10.1093/nar/gkq1222
PMCID: PMC3074145  PMID: 21109535
11.  Characterisation of the SUMO-Like Domains of Schizosaccharomyces pombe Rad60 
PLoS ONE  2010;5(9):e13009.
The S. pombe Rad60 protein is required for the repair of DNA double strand breaks, recovery from replication arrest, and is essential for cell viability. It has two SUMO-like domains (SLDs) at its C-terminus, an SXS motif and three sequences that have been proposed to be SUMO-binding motifs (SBMs). SMB1 is located in the middle of the protein, SBM2 is in SLD1 and SBM3 is at the C-terminus of SLD2. We have probed the functions of the two SUMO-like domains, SLD1 and SLD2, and the putative SBMs. SLD1 is essential for viability, while SLD2 is not. rad60-SLD2Δ cells are sensitive to DNA damaging agents and hydroxyurea. Neither ubiquitin nor SUMO can replace SLD1 or SLD2. Cells in which either SBM1 or SBM2 has been mutated are viable and are wild type for response to MMS and HU. In contrast mutation of SBM3 results in significant sensitivity to MMS and HU. These results indicate that the lethality resulting from deletion of SLD1 is not due to loss of SBM2, but that mutation of SBM3 produces a more severe phenotype than does deletion of SLD2. Using chemical denaturation studies, FPLC and dynamic light scattering we show this is likely due to the destabilisation of SLD2. Thus we propose that the region corresponding to the putative SBM3 forms part of the hydrophobic core of SLD2 and is not a SUMO-interacting motif. Over-expression of Hus5, which is the SUMO conjugating enzyme and known to interact with Rad60, does not rescue rad60-SLD2Δ, implying that as well as having a role in the sumoylation process as previously described [1], Rad60 has a Hus5-independent function.
doi:10.1371/journal.pone.0013009
PMCID: PMC2946365  PMID: 20885950
12.  Functionalized Mesoporous SBA-15 with CeF3: Eu3+ Nanoparticle by Three Different Methods: Synthesis, Characterization, and Photoluminescence 
Nanoscale Research Letters  2010;5(4):701-708.
Luminescence functionalization of the ordered mesoporous SBA-15 silica is realized by depositing a CeF3: Eu3+ phosphor layer on its surface (denoted as CeF3: Eu3+/SBA-15/IS, CeF3: Eu3+/SBA-15/SI and CeF3: Eu3+/SBA-15/SS) using three different methods, which are reaction in situ (I-S), solution impregnation (S-I) and solid phase grinding synthesis (S-S), respectively. The structure, morphology, porosity, and optical properties of the materials are well characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption, and photoluminescence spectra. These materials all have high surface area, uniformity in the mesostructure and crystallinity. As expected, the pore volume, surface area, and pore size of SBA-15 decrease in sequence after deposition of the CeF3: Eu3+ nanophosphors. Furthermore, the efficient energy transfer in mesoporous material mainly occurs between the Ce3+ and the central Eu3+ ion. They show the characteristic emission of Ce3+ 5d → 4f (200–320 nm) and Eu3+5D0 → 7FJ (J = 1–4, with 5D0 → 7F1 orange emission at 588 nm as the strongest one) transitions, respectively. In addition, for comparison, the mesoporous material CeF3: Eu3+/SBA-15/SS exhibits the characteristic emission of Eu3+ ion under UV irradiation with higher luminescence intensity than the other materials.
doi:10.1007/s11671-010-9534-0
PMCID: PMC2894170  PMID: 20672063
Mesoporous material; Nanoparticle; Luminescence; Cerium trifluoride doped with europium ion
13.  Functionalized Mesoporous SBA-15 with CeF3: Eu3+ Nanoparticle by Three Different Methods: Synthesis, Characterization, and Photoluminescence 
Nanoscale Research Letters  2010;5(4):701-708.
Luminescence functionalization of the ordered mesoporous SBA-15 silica is realized by depositing a CeF3: Eu3+ phosphor layer on its surface (denoted as CeF3: Eu3+/SBA-15/IS, CeF3: Eu3+/SBA-15/SI and CeF3: Eu3+/SBA-15/SS) using three different methods, which are reaction in situ (I-S), solution impregnation (S-I) and solid phase grinding synthesis (S-S), respectively. The structure, morphology, porosity, and optical properties of the materials are well characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, N2 adsorption, and photoluminescence spectra. These materials all have high surface area, uniformity in the mesostructure and crystallinity. As expected, the pore volume, surface area, and pore size of SBA-15 decrease in sequence after deposition of the CeF3: Eu3+ nanophosphors. Furthermore, the efficient energy transfer in mesoporous material mainly occurs between the Ce3+ and the central Eu3+ ion. They show the characteristic emission of Ce3+ 5d → 4f (200–320 nm) and Eu3+5D0 → 7FJ(J = 1–4, with 5D0 → 7F1 orange emission at 588 nm as the strongest one) transitions, respectively. In addition, for comparison, the mesoporous material CeF3: Eu3+/SBA-15/SS exhibits the characteristic emission of Eu3+ ion under UV irradiation with higher luminescence intensity than the other materials.
doi:10.1007/s11671-010-9534-0
PMCID: PMC2894170  PMID: 20672063
Mesoporous material; Nanoparticle; Luminescence; Cerium trifluoride doped with europium ion
14.  Wide Distribution of a Novel pmoA-Like Gene Copy among Type II Methanotrophs, and Its Expression in Methylocystis Strain SC2 
Experiments were conducted to determine if a novel pmoA-like gene (pmoA2) recently discovered in the methane-oxidizing bacterium Methylocystis strain SC2 (P. F. Dunfield, M. Tchawa Yimga, S. D. Dedysh, U. Berger, W. Liesack, and J. Heyer, FEMS Microbiol. Ecol. 41:17-26, 2002) is present in other methane-oxidizing bacteria (MOB), and if it is expressed. A newly developed primer combination (pmoA206f-pmoA703b) allowed a differential detection of pmoA1 and pmoA2. By using this primer combination, we identified pmoA2 in a wide range of type II MOB of the Methylosinus-Methylocystis group. However, screening by PCR and by Southern hybridization using a newly developed pmoA2-specific oligonucleotide probe also showed that closely related type II MOB, exhibiting 16S rRNA gene sequence identities of higher than 97%, may or may not harbor pmoA2. No pmoA2 was detected in five type I MOB tested: Methylococcus capsulatus strain Bath, Methylocaldum strain E10A, Methylobacter luteus, Methylomicrobium album, and Methylomonas strain D1a. In comparative sequence analyses, all pmoA2-like sequences formed a coherent cluster clearly distinct from pmoA1 sequences of type I and type II MOB, and from amoA sequences of the Nitrosomonas-Nitrosospira group. Phylogenetic analysis using the paml model suggested that pmoA2 is subject to strong purifying selection and therefore has an important cellular function. We probed total RNA extracts of Methylocystis strain SC2 for gene expression of pmoA. A strong signal was observed for pmoA1 in Northern hybridization, while the results obtained for pmoA2 were ambiguous. However, reverse transcription-PCR confirmed that pmoA2 was expressed, albeit at lower level than pmoA1. This provided experimental evidence that the gene product of pmoA2 may be a functionally active enzyme.
doi:10.1128/AEM.69.9.5593-5602.2003
PMCID: PMC194948  PMID: 12957949
15.  Simple Systematic Synthesis of Periodic Mesoporous Organosilica Nanoparticles with Adjustable Aspect Ratios 
Nanoscale Research Letters  2009;4(12):1524-1529.
One-dimensional periodic mesoporous organosilica (PMO) nanoparticles with tunable aspect ratios are obtained from a chain-type molecular precursor octaethoxy-1,3,5-trisilapentane. The aspect ratio can be tuned from 2:1 to >20:1 simply by variation in the precursor concentration in acidic aqueous solutions containing constant amounts of triblock copolymer Pluronic P123. The mesochannels are highly ordered and are oriented parallel to the longitudinal axis of the PMO particles. No significant Si–C bond cleavage occurs during the synthesis according to 29Si MAS NMR. The materials exhibit surface areas between 181 and 936 m2 g−1.
doi:10.1007/s11671-009-9430-7
PMCID: PMC2893839  PMID: 20651927
Periodic mesoporous organosilicas; One-dimensional nanostructures; Synthesis
16.  Simple Systematic Synthesis of Periodic Mesoporous Organosilica Nanoparticles with Adjustable Aspect Ratios 
Nanoscale Research Letters  2009;4(12):1524-1529.
One-dimensional periodic mesoporous organosilica (PMO) nanoparticles with tunable aspect ratios are obtained from a chain-type molecular precursor octaethoxy-1,3,5-trisilapentane. The aspect ratio can be tuned from 2:1 to >20:1 simply by variation in the precursor concentration in acidic aqueous solutions containing constant amounts of triblock copolymer Pluronic P123. The mesochannels are highly ordered and are oriented parallel to the longitudinal axis of the PMO particles. No significant Si–C bond cleavage occurs during the synthesis according to29Si MAS NMR. The materials exhibit surface areas between 181 and 936 m2 g−1.
doi:10.1007/s11671-009-9430-7
PMCID: PMC2893839  PMID: 20651927
Periodic mesoporous organosilicas; One-dimensional nanostructures; Synthesis
17.  Study of the effect of nano-sized precipitates on the mechanical properties of boron-added low-carbon steels by neutron scattering techniques 
Journal of Applied Crystallography  2008;41(Pt 5):906-912.
The effect of nano-sized precipitates on the mechanical properties of boron-added low-carbon steels was studied by neutron scattering techniques such as powder diffraction, small-angle scattering and particle tracking autography.
Small-angle neutron scattering (SANS) and neutron powder diffraction (ND) techniques were used to study quantitatively the effect of nano-sized precipitates and boron addition on the mechanical properties of low-carbon steels. SANS was used to evaluate nano-sized precipitates, smaller than about 600 Å in diameter, and ND was used to determine the weight fraction of the cementite precipitates. Fine core–shell structured spherical precipitates with an average radius of ~50 Å, such as MnS and/or CuS, surrounded by BN layers were observed in the boron-added (BA) low-carbon steels; fine spherical precipitates with an average radius of ~48 Å were mainly observed in the boron-free (BF) low-carbon steels. In the BA steels, the number of boron precipitates, such as BN, Fe3(C,B) and MnS, surrounded by BN layers increased drastically at higher hot-rolling temperatures. The volume fraction of the fine precipitates of the BA steels was higher than that of the BF steels; this difference is related to the rapid growth of the BN layers on the MnS and CuS precipitates. Boron addition to low-carbon steels resulted in a reduction in strength and an improvement in elongation; this behaviour is related to the reduction of the solute carbon and the nitrogen contents in the ferrite matrix caused by the precipitation of BN, as well by the increase in the volume fraction of the cementites.
doi:10.1107/S0021889808020943
PMCID: PMC2553556  PMID: 19461851
neutron diffraction; small-angle neutron scattering (SANS); boron-added low-carbon steel; elongation; cementite; precipitates; particle tracking autoradiography
18.  Infuence of Microstructure in Drug Release Behavior of Silica Nanocapsules 
Journal of Drug Delivery  2013;2013:803585.
Meso- and nanoporous structures are adequate matrices for controlled drug delivery systems, due to their large surface areas and to their bioactive and biocompatibility properties. Mesoporous materials of type SBA-15, synthesized under different pH conditions, and zeolite beta were studied in order to compare the different intrinsic morphological characteristics as pore size, pore connectivity, and pore geometry on the drug loading and release process. These materials were characterized by X-ray diffraction, nitrogen adsorption, scanning and transmission electron microscopy, and calorimetric measurements. Ibuprofen (IBU) was chosen as a model drug for the formulation of controlled-release dosage forms; it was impregnated into these two types of materials by a soaking procedure during different periods. Drug loading and release studies were followed by UV-Vis spectrophotometry. All nano- and mesostructured materials showed a similar loading behavior. It was found that the pore size and Al content strongly influenced the release process. These results suggest that the framework structure and architecture affect the drug adsorption and release properties of these materials. Both materials offer a good potential for a controlled delivery system of ibuprofen.
doi:10.1155/2013/803585
PMCID: PMC3748776  PMID: 23986870
19.  One millimetre makes the difference: high-resolution analysis of methane-oxidizing bacteria and their specific activity at the oxic–anoxic interface in a flooded paddy soil 
The ISME Journal  2012;6(11):2128-2139.
Aerobic methane-oxidizing bacteria (MOB) use a restricted substrate range, yet >30 species-equivalent operational taxonomical units (OTUs) are found in one paddy soil. How these OTUs physically share their microhabitat is unknown. Here we highly resolved the vertical distribution of MOB and their activity. Using microcosms and cryosectioning, we sub-sampled the top 3-mm of a water-saturated soil at near in situ conditions in 100-μm steps. We assessed the community structure and activity using the particulate methane monooxygenase gene pmoA as a functional and phylogenetic marker by terminal restriction fragment length polymorphism (t-RFLP), a pmoA-specific diagnostic microarray, and cloning and sequencing. pmoA genes and transcripts were quantified using competitive reverse transcriptase PCR combined with t-RFLP. Only a subset of the methanotroph community was active. Oxygen microprofiles showed that 89% of total respiration was confined to a 0.67-mm-thick zone immediately above the oxic–anoxic interface, most probably driven by methane oxidation. In this zone, a Methylobacter-affiliated OTU was highly active with up to 18 pmoA transcripts per cell and seemed to be adapted to oxygen and methane concentrations in the micromolar range. Analysis of transcripts with a pmoA-specific microarray found a Methylosarcina-affiliated OTU associated with the surface zone. High oxygen but only nanomolar methane concentrations at the surface suggested an adaptation of this OTU to oligotrophic conditions. No transcripts of type II methanotrophs (Methylosinus, Methylocystis) were found, which indicated that this group was represented by resting stages only. Hence, different OTUs within a single guild shared the same microenvironment and exploited different niches.
doi:10.1038/ismej.2012.57
PMCID: PMC3475382  PMID: 22695859
methane-oxidizing bacteria; paddy soil; microarray; competitive PCR; pmoA; mmoX
20.  The Relationship Between Depressive/Anxiety Symptoms During Pregnancy/Postpartum and Sexual Life Decline after Delivery 
The journal of sexual medicine  2013;10(5):1343-1349.
Introduction
Several factors have been found to be independently associated with decline in sexual activity after delivery. However, the association between depression in pregnancy/postpartum and sexual problems is less clear.
Aim
To prospectively evaluate the relationship between depressive/anxiety symptoms (DAS) during the perinatal period and sexual life in the postpartum period.
Methods
A prospective cohort study conducted between May 2005 and March 2007 included 831 pregnant women recruited from primary care clinics of the public sector in São Paulo, Brazil. Four groups with DAS during antenatal and postpartum periods were identified using the Self Report Questionnaire (SRQ-20): absence of both antenatal and postpartum DAS; presence of antenatal DAS only; presence of postpartum DAS only; and presence of both antenatal and postpartum DAS. The primary outcome was perception of sexual life decline (SLD) before and after pregnancy/delivery. Crude and adjusted risk ratios (RR), with 95% confidence intervals (95% CI), were calculated using Poisson regression to examine the associations between DAS and SLD.
Main Outcome Measure
The main outcome measure of this study is the perception of SLD before and after pregnancy/delivery.
Results
SLD occurred in 21.1% of the cohort. In the multivariable analysis, the following variables were independently associated with SLD: DAS during both pregnancy and postpartum (RR: 3.17 [95% CI: 2.18–4.59]); DAS during only the postpartum period (RR: 3.45 [95% CI: 2.39–4.98]); a previous miscarriage (RR: 1.54 [95% CI: 1.06–2.23]); and maternal age (RR: 2.11 [95% CI: 1.22–3.65]).
Conclusions
Postpartum women with DAS have an increased likelihood for SLD up to 18 months after delivery. Efforts to improve the rates of recognition and treatment of perinatal depression/anxiety in primary care settings have the potential to preserve sexual functioning for low-income mothers.
doi:10.1111/jsm.12092
PMCID: PMC3727156  PMID: 23433352
Pregnancy; Postpartum; Postpartum Depression; Sexual Functioning; Anxiety; Antenatal Depression
21.  Template Synthesis of Three-Dimensional Cubic Ordered Mesoporous Carbon With Tunable Pore Sizes 
Nanoscale Research Letters  2009;5(1):103-107.
Three-dimensional cubic ordered mesoporous carbons with tunable pore sizes have been synthesized by using cubic Ia3d mesoporous KIT-6 silica as the hard template and boric acid as the pore expanding agent. The prepared ordered mesoporous carbons were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption analysis. The results show that the pore sizes of the prepared ordered mesoporous carbons with three-dimensional cubic structure can be regulated in the range of 3.9–9.4 nm. A simplified model was proposed to analyze the tailored pore sizes of the prepared ordered mesoporous carbons on the basis of the structural parameters of the silica template.
doi:10.1007/s11671-009-9450-3
PMCID: PMC2894178  PMID: 20652150
Template synthesis; Mesoporous carbon; Mesoporous silica; Pore size control; KIT-6
22.  Template Synthesis of Three-Dimensional Cubic Ordered Mesoporous Carbon With Tunable Pore Sizes 
Nanoscale Research Letters  2009;5(1):103-107.
Three-dimensional cubic ordered mesoporous carbons with tunable pore sizes have been synthesized by using cubic Ia3d mesoporous KIT-6 silica as the hard template and boric acid as the pore expanding agent. The prepared ordered mesoporous carbons were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption analysis. The results show that the pore sizes of the prepared ordered mesoporous carbons with three-dimensional cubic structure can be regulated in the range of 3.9–9.4 nm. A simplified model was proposed to analyze the tailored pore sizes of the prepared ordered mesoporous carbons on the basis of the structural parameters of the silica template.
doi:10.1007/s11671-009-9450-3
PMCID: PMC2894178  PMID: 20652150
Template synthesis; Mesoporous carbon; Mesoporous silica; Pore size control; KIT-6
23.  Facile synthesis of water-soluble luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres 
Nanoscale Research Letters  2013;8(1):163.
Luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres were synthesized through W/O microemulsion process at ambient temperature. The negatively charged silica favors a coating of the positively charged Tb3+ composite. Thus, silicon layer was adsorbed on the surface of Tb(OH)3 groups to form Tb-O-Si through electrostatic interaction. X-ray diffraction, field emission transmission electron microscopy (FE-TEM), energy-dispersive X-ray spectrometry, and Fourier transform infrared, UV/Visible, and photoluminescence spectroscopies were applied to examine the phase purity, crystallinity, surface morphology, and optical properties of the core-shell nanospheres. The FE-TEM results have revealed typically ordered mesoporous characteristics of the material with monodisperse spherical morphology in a narrow size distribution. The luminescent mesoporous core-shell nanospheres exposed remarkable splitting with broadening in the emission transition 5D4 → 7F5 (543 nm). In addition, the luminescent mesoporous core-shell nanospheres emit strong green fluorescence (from Tb3+) in the middle of the visible region under 325 nm (3.8) excitation. The luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres can therefore be exploited as fluorescent probes in biomarkers or biolabeling, optical sensing, and drug delivery system. Further, these nanospheres could have potential use as scattering layers in dye-sensitized solar cells.
doi:10.1186/1556-276X-8-163
PMCID: PMC3660165  PMID: 23574757
Luminescent mesoporous Tb(OH)3@SiO2 core-shell nanospheres; Optical properties; Photoluminescence
24.  Covalent Anchoring of Chloroperoxidase and Glucose Oxidase on the Mesoporous Molecular Sieve SBA-15 
Functionalization of porous solids plays an important role in many areas, including heterogeneous catalysis and enzyme immobilization. In this study, large-pore ordered mesoporous SBA-15 molecular sieves were synthesized with tetraethyl orthosilicate (TEOS) in the presence of the non-ionic triblock co-polymer Pluronic P123 under acidic conditions. These materials were grafted with 3-aminopropyltrimethoxysilane (ATS), 3-glycidoxypropyltrimethoxysilane (GTS) and with 3-aminopropyltrimethoxysilane and glutaraldehyde (GA-ATS) in order to provide covalent anchoring points for enzymes. The samples were characterized by nitrogen adsorption, powder X-ray diffraction, solid-state NMR spectroscopy, elemental analysis, diffuse reflectance fourier transform infrared spectroscopy and diffuse reflectance UV/Vis spectroscopy. The obtained grafted materials were then used for the immobilization of chloroperoxidase (CPO) and glucose oxidase (GOx) and the resulting biocatalysts were tested in the oxidation of indole. It is found that enzymes anchored to the mesoporous host by the organic moieties can be stored for weeks without losing their activity. Furthermore, the covalently linked enzymes are shown to be less prone to leaching than the physically adsorbed enzymes, as tested in a fixed-bed reactor under continuous operation conditions.
doi:10.3390/ijms11020762
PMCID: PMC2852867  PMID: 20386667
functionalization; mesoporous silica; enzyme immobilization
25.  Modulation of microporous/mesoporous structures in self-templated cobalt-silica 
Scientific Reports  2015;5:7970.
Finite control of pore size distributions is a highly desired attribute when producing porous materials. While many methodologies strive to produce such materials through one-pot strategies, oftentimes the pore structure requires post-treatment modification. In this study, modulation of pore size in cobalt-silica systems was investigated by a novel, non-destructive, self-templated method. These systems were produced from two cobalt-containing silica starting materials which differed by extent of condensation. These starting materials, sol (SG′) and xerogel (XG′), were mixed with pure silica sol to produce materials containing 5–40 mol% Co. The resultant SG-series materials exhibited typical attributes for cobalt-silica systems: mesoporous characteristics developed at high cobalt concentrations, coinciding with Co3O4 formation; whereas, in the XG-series materials, these mesoporous characteristics were extensively suppressed. Based on an examination of the resultant materials a mechanism describing the pore size formation and modulation of the two systems was proposed. Pore size modulation in the XG-series was caused, in part, by the cobalt source acting as an autogenous template for the condensation of the silica network. These domains could be modified when wetted, allowing for the infiltration and subsequent condensation of silica oligomers into the pre-formed, mesoporous cages, leading to a reduction in the mesoporous content of the final product.
doi:10.1038/srep07970
PMCID: PMC4302294  PMID: 25609189

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