Fabrication of alginate-based hydrogel microparticle via ruthenium-catalyzed photocrosslinking.

In this study, we developed an alginate-based microparticle production process via sodium ruthenium(II) tris-bipyridyl dication (Ru)/ammonium persulfate (SPS)-mediated visible light crosslinking system using a microfluidic device. Microparticles were prepared by crosslinking phenolic-substituted alginate (AlgPh) and incorporated gelatin (GelPh) in an aqueous solution containing SPS, which flowed into an ambient immiscible liquid paraffin-containing Ru using coaxial double orifice microfluidic device. The hydrogel microparticles appeared with the desired geometries and dimensions under optimal conditions. The concentration of AlgPh and light intensity were the most critical parameters for harvesting spherical microparticles with homogeneous size distribution. The physical properties of the prepared AlgPh microparticles were characterized and compared with Alg-Ca microparticles. Cell viability and proliferation preserved on AlgPh/GelPh hydrogel surfaces. Also, encapsulated cells in microparticles were also viable and proliferated well over 13 days after encapsulation. In brief, the results proved the feasibility of fabricating AlgPh vehicles via Ru/SPS-mediated system and visible light irradiation as a simple and efficient three-dimensional platform, which are applicable for various tissue engineering and cell delivery purposes.

Preparation and characterization of PLGA nanospheres loaded with inactivated influenza virus, CpG-ODN and Quillaja saponin.

OBJECTIVES: The purpose of this study was preparation and evaluation of PLGA nanospheres containing the influenza virus and different adjuvants, Quillaja saponin (QS) and CpG-ODN. MATERIALS AND METHODS: Nanospheres were prepared using the double emulsion-solvent evaporation method. The morphological and physicochemical properties were studied by scanning electron microscopy (SEM), determination of zeta potential, encapsulation efficiency and release profile. RESULTS: The particle size of formulations was less than 1000 nm, except for formulations containing antigen. The results were confirmed with SEM images. Encapsulation efficiency of antigen, QS and CpG ODN were 80%, 62% and 31%, respectively. The zeta potential of nanospheres was about -30 mV. The burst release was observed for all encapsulates and reached to about 48%, 44% and 35% within 90 min for antigen, CpG-ODN and Qs content, respectively. CONCLUSION: The formulations showed proper physicochemical properties. These nanospheres have good potential to be used as delivery systems/adjuvants for immunization against influenza.