No abstract

No abstract

Regarding safety concerns, nonviral gene delivery vehicles that have the required efficiency and safety for use in human gene therapy are being widely investigated. The aim of this study was to synthesize and evaluate a thiolated chitosan to improve the efficacy of oral gene delivery systems. Thiolated chitosan was synthesized by introducing thioglycolic acid (TGA) to chitosan via amide bond formation mediated by a carbodiimide. Based on this conjugate, nanoparticles with pDNA were generated at pH 4.0 and 5.0. Cytotoxicity of the thiolated chitosan/pDNA nanoparticles on Caco-2 cells was evaluated. The diameter of thiolated chitosan/pDNA nanoparticles was in the range of 100-200 nm. The zeta potential was determined to be 5-6 mV. Due to stability toward nucleases, the transfection rate of thiolated chitosan/pDNA nanoparticles was fivefold higher than that of unmodified chitosan/pDNA nanoparticles. Lactate dehydrogenase tests for thiolated chitosan/pDNA (pH 4.0 and 5.0) showed that (3.79 +/- 0.23)% and (2.9 +/- 0.13)% cell damage. According to these results, thiolated chitosan represents promising excipients for preparation DNA nanoparticles in nonviral gene delivery system.

In the current report, hollow mesoporous silica (HMS) nanoparticles were successfully prepared by means of a hard-templating method and further modified with poly(styrene sulfonate) (PSS) via radical polymerization. Structural analysis, surface spectroscopy, and thermogravimetric characterization confirmed a successful surface modification of HMS nanoparticles. A hairy PSS was clearly visualized by high-resolution transmission electron microscopy measurement, and it is grown on the surface of HMS nanoparticles. The Brunauer− Emmett−Teller surface area and average pore size of HMS nanoparticles were reduced after surface modification because of the pore-blocking effect, which indicated that the PSS lies on the surface of nanoparticles. Nevertheless, the PSS acts as a "nano-gate" to control the release of curcumin which is triggered by pH. The drug-release profile of unmodified HMS nanoparticles showed a stormed release in both pH 7.4 and 5.0 of phosphate buffer saline buffer solution. However, a slow release (9.92% of cumulative release) of curcumin was observed at pH 7.4 when the surface of HMS nanoparticles was modified by PSS. The kinetic release study showed that the curcumin release mechanism from PSS@HMS nanoparticles followed the Ritger−Peppas kinetic model, which is the non-Fickian diffusion. Therefore, the PSS-decorated HMS nanoparticles demonstrate potential for pH-triggered drug release transport.

The aim of this study was to monitor the expression of secreted protein in differentiated Caco-2 cells after transfection with nanoparticles, in order to improve gene delivery. Based on unmodified chitosan and thiolated chitosan conjugates, nanoparticles with the gene reporter pSEAP (recombinant Secreted Alkaline Phosphatase) were generated at pH 4.0. Transfection studies of thiolated chitosan in Caco-2 cells during the exponential growth phase and differentiation growth phase of the cells led to a 5.0-fold and 2.0-fold increase in protein expression when compared to unmodified chitosan nanoparticles. The mean particle size for both unmodified chitosan and cross-linked thiolated chitosan nanoparticles is 212.2 ± 86 and 113.6 ± 40 nm, respectively. The zeta potential of nanoparticles was determined to be 7.9 ± 0.38 mV for unmodified chitosan nanoparticles and 4.3 ± 0.74 mV for cross-linked thiolated chitosan nanoparticles. Red blood cell lysis evaluation was used to evaluate the membrane damaging properties of unmodified and thiolated chitosan nanoparticles and led to 4.61 ± 0.36% and 2.29 ± 0.25% lysis, respectively. Additionally, cross-linked thiolated chitosan nanoparticles were found to exhibit higher stability toward degradation in gastric juices. Furthermore the reversible effect of thiolated chitosan on barrier properties was monitored by measuring the transepithelial electrical resistance (TEER) and is supported by immunohistochemical staining for the tight junction protein claudin. According to these results cross-linked thiolated chitosan nanoparticles have the potential to be used as a non-viral vector system for gene therapy.