Preparation of PLGA-TQ nanoparticles Nanoparticles were prepared with poly (dl-lactide-coglycolide) using S/O/W, an emulsification-solvent evaporation/diffusion method with slight modifications (Xie et al., 2011) . Briefly, 45 mg of PLGA was dissolved in 2 ml of dicholoromethane (HPLC-grade) as an oil phase for 12 hr in at room temperature to obtain uniform solution. 5 mg of bioactive liphophillic compound-TQ was added to the above solution. Then the suspension was sonicated for 2 minutes to

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... erate S/O primary emulsion. This mixture was emulsified with an aqueous phase of 20 ml of PVA (1% w/v) to form S-O/W emulsion by rotating in Magnetic stirrer (REMI, India) at 400 rpm. Once all the compound/polymer mixture was added the contents were vortexed for 10 sec at a high setting. The resulting suspension was sonicated (Ultra Sonicator bath-INKARP) for 3min to generate the final S/O/W emulsion. Then organic solvent present in suspension was evaporated by rotary vacuum evaporation using Rotary evaporator (Heidolph) at 50°C. The nanoparticles were then collected by centrifugation at 10000g for 20 min at 4°C. Finally, they ORIGINAL RESEARCH ARTICLE OPEN ACCESS International Current Pharmaceutical Journal ABSTRACT The aim of the present study was to synthesize and characterize the Thymoquinone (TQ) encapsulated PLGA (poly (dl-lactide-coglycolide) nanoparticles, and further evaluate for its antioxidant and anti-bacterial activities. TQ is a potential active ingredient of Nigella sativa seed and possess a spectrum of therapeutic properties. Nanoparticles were prepared according to solid-in-oil-in-water (s/o/w) solvent evaporation method. Dynamic laser light scattering (DLS) and SEM studies indicated a mean particle size of < 200 nm. The success of encapsulation was confirmed by FTIR technique, and the encapsulation efficiency (EE) of TQ was determined to be 62%. In vitro drug release study showed a maximum release of TQ at 75% and 54 % respectively for artificial intestinal and gastric juices over the period of 7 days. DPPH radical scavenging activity of the nanoparticles was found to be 71% at 1 mg/ml concentration. It also exhibited antibacterial property against E. coli, Staphylococcus aureus and Salmonella typhi strains, tested using well diffusion method. In conclusion, our study shows that PLGA encapsulated TQ nanoparticle with sustained release property has preserved antioxidant as well as anti-microbial activity, and therefore suggesting its therapeutic applications in various food samples.