Development of mangiferin loaded chitosan-silica hybrid scaffolds: Physicochemical and bioactivity characterization.

Development of hybrid materials with molecular structure of organic-inorganic co-network is a promising method to enhance the stability and mechanical properties of biopolymers. Chitosan-silica hybrid nanocomposite scaffolds loaded with mangiferin, a plant-derived active compound possessing several bioactivities, were fabricated using the sol-gel synthesis and the freeze-drying processes. Investigation on the physicochemical and mechanical properties of the fabricated scaffolds showed that their properties can be improved and tailored by the formation of 3-dimensional crosslinked network and the addition of ZnO nanoparticles. The scaffolds possessed porosity, fluid uptake, morphology, thermal properties and mechanical strength suitable for bone tissue engineering application. Investigation on the biomineralization and cell viability indicated that the inclusion of bioactive mangiferin further promote potential use of the hybrid nanocomposite scaffolds in guided bone regeneration application.

Simple Colorimetric Assay for Vibrio parahaemolyticus Detection Using Aptamer-Functionalized Nanoparticles.

Simple, rapid, and sensitive screening methods are the key to prevent and control the spread of foodborne diseases. In this study, a simple visual colorimetric assay using magnetic nanoparticles (MNPs) and gold nanoparticles (AuNPs) was developed for the detection of Vibrio parahaemolyticus. First, the aptamer responding to V. parahaemolyticus was conjugated onto the surface of MNPs and used as a specific magnetic separator. In addition, the aptamer was also immobilized on the surface of AuNPs and used as a colorimetric detector. In the presence of V. parahaemolyticus, a sandwich structure of MNP-aptamer-bacteria-aptamer-AuNPs is formed through specific recognition of the aptamer and V. parahaemolyticus. The magnetic separation technique was then applied to generate a detection signal. Owing to the optical properties of AuNPs, a visual signal could be observed, resulting in an instrument-free colorimetric detection. Under optimal conditions, this assay shows a linear response toward V. parahaemolyticus concentration through the range of 10-106 cfu/mL, with a limit of detection of 2.4 cfu/mL. This method was also successfully applied for V. parahaemolyticus detection in spiked raw shrimp samples.

Biocompatible zwitterionic copolymer-stabilized magnetite nanoparticles: a simple one-pot synthesis, antifouling properties and biomagnetic separation.

A simple one-pot synthesis of biocompatible and antifouling magnetite nanoparticles (Fe3O4NPs) was developed. The process involves co-precipitation and in situ coating of zwitterionic copolymer poly[(methacrylic acid)-co-(2-methacryloyloxyethyl phosphorylcholine)] (PMAMPC). The influence of one-step and two-step coating methods on the performance of modified Fe3O4NP was investigated. The PMAMPC-Fe3O4NP with a narrow particle size distribution obtained from the two-step approach were highly stable in aqueous media within a wide range of pH. The particles exhibited superparamagnetic behavior with high saturation magnetization values so that they could be easily separated from solution by a magnet. Their antifouling characteristics against 2 selected proteins, lysozyme (LYZ) and bovine serum albumin (BSA), as a function of copolymer molecular weight and composition were also evaluated. Moreover, taking advantage of having carboxyl groups in the coated copolymer, the PMAMPC-Fe3O4NP were conjugated with a model biomolecular probe, biotin. The biotin-immobilized PMAMPC-Fe3O4NP were then tested for their specific capturing of a target molecule, streptavidin. The results have demonstrated the potential of PMAMPC-Fe3O4NP prepared by the two-step in situ coating method for probe immobilization and subsequent biomagnetic separation of target molecules. The fact that the developed functionalizable magnetite nanoparticles are biocompatible and antifouling also opens up the possibility of their use in other biomedical-relevant applications.

Non-cytotoxic hybrid bioscaffolds of chitosan-silica: Sol-gel synthesis, characterization and proposed application.

Biohybrid chitosan-silica scaffolds were synthesized through the sol-gel and the freeze drying processes. Hydrolysis and condensation of chitosan with tetraethylorthosilicate (TEOS) in the presence of 3-isocyanatopropyl triethoxysilane (ICPTES) were successfully carried out. Results obtained from FTIR, swelling test and pyrolysis confirmed that the hybrid scaffolds containing covalent coupling between the organic and inorganic networks were formed with high crosslink density of SiOSi bridging and could be classified as the class II material. The hybridization also resulted in improvements on mechanical strength and stability comparing to the pure chitosan. In vitro investigations on the guided bone regeneration and the cytotoxicity were also performed. SEM-EDS was used to examine the proliferation of calcium phosphate mineral at the scaffold surface after an immersion in simulated body fluid. The results revealed that the hybrid scaffolds exhibited a rapid induction of calcium phosphate mineral without cytotoxicity effect, reflecting an excellent in vitro bone bioactivity which was superior to the pure chitosan scaffold.