Synthesis and Characterization of Polymeric Microspheres Template for a Homogeneous and Porous Monolith

Monolith is an emerging technology applicable for separation, filtration, and chromatography due to its interconnected pore structure. However, the current templates used to form monolith pores are associated with poor heat dissipation, uneven pore size distribution, and relatively low mechanical strength during monolith scale-up. Templates made from polymeric microsphere particles were synthesized via a solvent evaporation technique using different types of polymer (polystyrene, polycaprolactone, polypropylene, polyethylene, and poly (vinyl-alcohol) at varied polymer (10–40 wt%) and surfactant (4–10%) concentrations. The resulting microsphere particles were tested as a monolith template for the formation of homogenous pores. Among the tested polymers, polystyrene at 10 wt% concentration demonstrated good particle morphology determined to around 1.94–3.45 µm. The addition of surfactant at a concentration of 7–10 wt% during microsphere synthesis resulted in the formation of well-shaped and non-aggregating microsphere particles. In addition, the template has contributed to the production of porous monoliths with enhanced thermal stability. The thermogravimetric analysis (TGA) indicated monolith degradation between 230 °C and 450 °C, implying the material excellent mechanical strength. The findings of the study provide insightful knowledge on the feasibility of polymeric microsphere particles as a pore-directing template to fabricate monoliths with desired pore structures.

Design, fabrication and evaluation of clotrimazole loaded polymeric microsphere based in situ ophthalmic gel

The present study was started with aim to design clotrimazole loaded polymeric microsphere based in situ ophthalmic gel for management of corneal fungal infections. The clotrimazole loaded microsphere was fabricated using various percentage of polylactide-co-glycolide polymer by solvent evaporation technique and evaluated for particle size, zeta potential and encapsulation efficiency. The polyvinyl alcohol was used as stabilizer. The formulation batch which showed good particle size and entrapment efficiency was selected for further study. The in situ ophthalmic gel of optimized drug loaded microsphere was formulated using various ratios of sodium alginate and hydroxy propyl methyl cellulose. The formulated gel was evaluated with respect to pH, in vitro gelling capacity, clarity, viscosity, in vitro antifungal activity and in vitro transcorneal permeation behavior. The fabricated drug loaded microspheres revealed acceptable particle size, zeta potential and encapsulation efficiency. The prepared in situ gels were clear and exhibited acceptable pH, rheological properties and in vitro gelation. The drug loaded microsphere based gel revealed superior in vitro antifungal activity against Aspergillus niger than conventional formulation and sufficient drug permeation across goat cornea. Thus, formulated clotrimazole loaded microsphere based in situ gel based systems can be a promising approach for sustained ophthalmic delivery of antifungal agents.