Jinghai Zhang

Spherical mesoporous silica nanoparticles for loading and release of the poorly water-soluble drug telmisartan

The purpose of this study was to develop mesoporous silica nanoparticles (MSNs) loaded with a poorly water-soluble drug, intended to be orally administered, able to improve the dissolution rate and enhance the drug loading capacity. Spherical MSNs were synthesized using an organic template method in an oil/water phase, and large pore diameter MSNs were functionalized with aminopropyl groups through postsynthesis. MSNs as well as the resulting functionalized MSNs were investigated as matrices for loading and release of the model drug telmisartan (TEL). The effects of different pore sizes and surface chemical groups on TEL uptake and release were systematically studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and HPLC. The total pore volume and the pore diameter of MSNs were the two main factors limiting the maximum drug load capacity. MSNs allow a very high drug loading of about 60% in weight. The release rate of TEL from MSNs with a pore diameter of 12.9 nm was found to be effectively increased and the release rate of TEL from the functionalized MSNs was effectively controlled compared with that from the unmodified MSNs. We believe that the present study will help in the design of oral drug delivery systems for the dissolution enhancement and/or sustained release of poorly water-soluble drugs.

Development of biodegradable porous starch foam for improving oral delivery of poorly water soluble drugs.

A biodegradable porous starch foam (BPSF) was developed for the first time as a carrier in order to improve the dissolution and enhance the oral bioavailability of lovastatin - defined as a model poorly water soluble BCS type II drug. In this paper, BPSF was prepared by the solvent exchange method and characterized by scanning electron microscopy (SEM) and nitrogen adsorption/desorption analysis in order to perform the morphological and structural characterization of BPSF. Lovastatin was loaded by immersion/solvent evaporation into the BPSF which provided a stable hydrophilic matrix with a nano-porous structure. The solid state properties of the loaded BPSF samples were characterized by SEM, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC). In vitro and in vivo drug release studies showed that when BPSF was used as a carrier it allowed immediate release of lovastatin and enhanced the dissolution rate in comparison with crystalline lovastatin and commercial capsules. These results provide important information about the mechanism of drug adsorption and release from BPSF as a carrier. Accordingly, BPSF has a promising future as a device for the oral delivery of poorly water soluble drugs.

Inclusion of the poorly water-soluble drug simvastatin in mesocellular foam nanoparticles: Drug loading and release properties

The purpose of this study was to develop spherical mesocellular foam (MCF) loaded with a poorly water-soluble drug, intended to be orally administered, able to improve the dissolution rate and enhance the drug loading capacity. Spherical MCF with a continuous 3-D pore system was synthesized using Pluronic 123 triblock polymer (P123) as a surfactant coupled with cetyltrimethyl ammonium bromide (CTAB) as a co-surfactant. A model drug, simvastatin (SV), was loaded onto spherical MCF via a procedure involving a combination of adsorption equilibrium and solvent evaporation. The drug release rate and the drug loading efficiency of spherical MCF were compared with those of fibrous SBA-15. Investigations using nitrogen adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and HPLC demonstrated the successful incorporation of SV into the MCF host. It was found that spherical MCF has a high drug loading efficiency up to 37.5%, and higher than that of fibrous SBA-15 with a pore diameter of 6.5 nm. It is worth noting that fast release rate of SV was obtained from spherical MCF compared with SBA-15 and pure crystalline SV using enzyme-free simulated intestinal fluid (SIF, pH 6.8).

Hyaluronic Acid Oligosaccharide Modified Redox-Responsive Mesoporous Silica Nanoparticles for Targeted Drug Delivery

A redox-responsive delivery system based on colloidal mesoporous silica (CMS) has been developed, in which 6-mercaptopurine (6-MP) was conjugated to vehicles by cleavable disulfide bonds. The oligosaccharide of hyaluronic acid (oHA) was modified on the surface of CMS by disulfide bonds as a targeting ligand and was able to increase the stability and biocompatibility of CMS under physiological conditions. In vitro release studies indicated that the cumulative release of 6-MP was less than 3% in the absence of glutathione (GSH), and reached nearly 80% within 2 h in the presence of 3 mM GSH. Confocal microscopy and fluorescence-activated cell sorter (FACS) methods were used to evaluate the cellular uptake performance of fluorescein isothiocyanate (FITC) labeled CMS, with and without oHA modification. The CMS-SS-oHA exhibited a higher cellular uptake performance via CD44 receptor-mediated endocytosis in HCT-116 (CD44 receptor-positive) cells than in NIH-3T3 (CD44 receptor-negative) cells. 6-MP loaded CMS-SS-oHA exhibited greater cytotoxicity against HCT-116 cells than NIH-3T3 cells due to the enhanced cell uptake behavior of CMS-SS-oHA. This study provides a novel strategy to covalently link bioactive drug and targeting ligand to the interiors and exteriors of mesoporous silica to construct a stimulus-responsive targeted drug delivery system.

Uniform mesoporous carbon as a carrier for poorly water soluble drug and its cytotoxicity study

In this study, uniform mesoporous carbon spheres (UMCS) with 3-D pore system and fibrous ordered mesoporous carbon (FOMC) with 2-dimensional hexagonal mesoporous structure were studied as drug carriers for oral drug delivery system. Lovastatin (LOV), which has low water solubility, was chosen as a model drug. Drug release rate and degree of drug loading of UMCS and FOMC were compared. The effects of different pore channel structures and pore sizes on LOV uptake and release were systematically investigated. Cytotoxicity of UMCS and FOMC on human colon carcinoma (Caco-2) cells were also studied. The results indicate that UMCS has a higher degree of drug loading (up to 36.26% drug weight/total weight) compared with FOMC. The dissolution rate of LOV from UMCS was found to be markedly increased compared with pure crystalline LOV, and the dissolution rate of LOV from FOMC was relatively sustained compared with UMCS, and both UMCS and FOMC exhibited a weak cytotoxicity at tested concentrations (10-800 μg/ml).

Kaempferol induces apoptosis in human HCT116 colon cancer cells via the Ataxia-Telangiectasia Mutated-p53 pathway with the involvement of p53 Upregulated Modulator of Apoptosis.

Dietary flavonols have been found to possess preventive and therapeutic potential against several kinds of cancers. This study is conducted to investigate the anti-proliferation effects of kaempferol, a major component of food flavonols, against colon cancer cells. In the human HCT116 colon cancer cell line, kaempferol induced p53-dependent growth inhibition and apoptosis. Furthermore, kaempferol was found to induce cytochrome c release from mitochondria and activate caspase-3 cleavage. The Bcl-2 family proteins including PUMA were involved in this process. Kaempferol also induced ATM and H2AX phosphorylation in HCT116 cells, inhibition of ATM by a chemical inhibitor resulted in abrogation of the downstream apoptotic cascades. These findings suggest kaempferol could be a potent candidate for colorectal cancer management.

Hybrid lipid-capped mesoporous silica for stimuli-responsive drug release and overcoming multidrug resistance.

Multidrug resistance (MDR) is known to be a great obstruction to successful chemotherapy, and considerable efforts have been devoted to reverse MDR including designing various functional drug delivery systems. In this study, hybrid lipid-capped mesoporous silica nanoparticles (LTMSNs), aimed toward achieving stimuli-responsive drug release to circumvent MDR, were specially designated for drug delivery. After modifying MSNs with hydrophobic chains through disulfide bond on the surface, lipid molecules composing polymer d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) with molar ratio of 5:1 were subsequently added to self-assemble into a surrounded lipid layer via hydrophobic interaction acting as smart valves to block the pore channels of carrier. The obtained LTMSNs had a narrow size distribution of ca. 190 nm and can be stably dispersed in body fluids, which may ensure a long circulating time and ideal enhanced permeability and retention effect. Doxorubicin (DOX) was chosen as a model drug to be encapsulated into LTMSNs. Results showed that this hybrid lipid-capped mesoporous silica drug delivery system can achieve redox and pH-responsive release of DOX, thereby avoiding the premature leakage of drug before reaching the specific site and releasing DOX within the cancerous cells. Owing to the presence of TPGS-containing lipid layer, LTMSNs-DOX exhibited higher uptake efficiency, cytotoxicity, and increased intracellular accumulation in resistant MCF-7/Adr cells compared with DOX solution, proving to be a promising vehicle to realize intracellular drug release and inhibit drug efflux.

RVG-peptide-linked trimethylated chitosan for delivery of siRNA to the brain.

In this work, a peptide derived from the rabies virus glycoprotein (RVG) was linked to siRNA/trimethylated chitosan (TMC) complexes through bifunctional PEG for efficient brain-targeted delivery of siRNA. The physiochemical properties of the complexes, such as siRNA complexing ability, size and ζ potential, morphology, serum stability, and cytotoxicity, were investigated prior to studying the cellular uptake, in vitro gene silencing efficiency, and in vivo biodistribution. The RVG-peptide-linked siRNA/TMC-PEG complexes showed increased serum stability, negligible cytotoxicity, and higher cellular uptake than the unmodified siRNA/TMC-mPEG complexes in acetylcholine receptor positive Neuro2a cells. The potent knockdown of BACE1, a therapeutic target in Alzheimers disease, demonstrated the gene silencing efficiency. In vivo imaging analysis showed significant accumulation of Cy5-siRNA in the isolated brain of mice injected with RVG-peptide-linked complexes. Therefore, the RVG-peptide-linked TMC-PEG developed in this study can be used as a potential carrier for delivery of siRNA to the brain.

Novel Chitosan-Functionalized Spherical Nanosilica Matrix As an Oral Sustained Drug Delivery System for Poorly Water-Soluble Drug Carvedilol

A novel spherical nanosilica matrix (SNM) together with chitosan (CTS) encapsulated SNM (CTS-SNM) was developed in order to investigate the feasibility of using chitosan to regulate drug release rate from porous silica and obtain an oral sustained drug delivery system. To achieve this goal, we synthesized a spherical nanosilica matrix (SNM) and incorporated chitosan chains on the SNM surface. Solvent evaporation method was adopted to load the model drug carvedilol into SNM and CTS-SNM. The physicochemical properties of the drug carriers and drug-loaded composites were systematically studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The structural changes in CTS-SNM in simulated gastrointestinal fluid as well as the relationships between swelling effect of chitosan and in vitro drug release behaviors were investigated. Pharmacokinetic and bioavailability aspects were also discussed. The results showed that the powerful dispersing effect of SNM and the blocking action due to the swelling of chitosan were the two main factors contributing to the sustained drug release behavior. The swelling effect of chitosan in an acidic environment together with the shrinking effect in a relatively alkaline environment allowed regulation of drug release behavior in simulated gastrointestinal fluid. An in vivo study showed that the bioavailability of CAR was improved 182% compared with that of the commercial capsule when SNM was used as the drug carrier. As for CAR-CTS-SNM, the T(max) of CAR was delayed by about 3.4 h and the bioavailability was slightly increased in comparison with the commercial capsule. We believe that SNM and CTS-SNM developed in this study will help increase the use of polymers and inorganic materials in pharmaceutical applications and stimulate the design of oral drug delivery systems for immediate or sustained release of poorly water-soluble drugs.

Inclusion of celecoxib into fibrous ordered mesoporous carbon for enhanced oral bioavailability and reduced gastric irritancy

Fibrous ordered mesoporous carbon (FOMC) was developed as a new drug delivery system for loading an insoluble drug, designed to be orally administered, and then to enhance the drug loading capacity, improve the dissolution rate, enhance the oral bioavailability and reduce the gastric damage. Celecoxib (CEL) was chosen as a model drug. The nanostructures and effect of different pore sizes (4.4-7.0 nm) on drug loading and release properties were studied. The results showed that FOMC has a high drug loading capacity (0.599 g/g, drug weight/carrier weight) and the dissolution rate of CEL from FOMC was much faster than pure crystalline CEL using buffer (pH 6.8) as a dissolution medium. Moreover, the oral bioavailability of CEL loaded into FOMC was significantly improved compared with that of CEL capsules and the gastric damage caused by CEL which was loaded in FOMC was also reduced, demonstrating the protective effect of FOMC.