Formulation of chrysin loaded nanostructured lipid carriers using Box Behnken design, its characterization and antibacterial evaluation alone and in presence of probiotics co-loaded in gel

The present study deciphers formulation, optimization and characterization of chrysin nanostructured lipid carriers with probiotics (PB) loaded gel (Chrysin (CS)-Nanostructured lipid carriers (NLCs) + PB loaded gel) for topical application. Hot homogenization-probe sonication method was used to formulate NLCs. Formulation parameters were optimized using Box Behnken Design. The optimized formulation was characterized for particle size (PS), zeta potential (ZP), % entrapment efficiency (%EE), % drug loading (%DL). The optimized values were found to be 199.99 mg, 33.92 mg, 700 mg and 376.86 mg of solid lipid, liquid lipid, surfactant and co-surfactant respectively. The PS, ZP, % EE and % DL of optimized CS-NLCs + PB loaded gel were found to be 66.45 +/- 5.62 nm,-22 +/- 5.21 mV, 97.25 +/- 0.15 and 82.3 +/- 0.104, respectively. Transmission electron microscopic images revealed that NLCs loaded with CS were spherical in shape. The in vitro diffusion studies revealed that 98 +/- 0.06% of CS got released from CS-NLCs + PB loaded gel at the end of 48 h. For initial 8h, release of CS was about 6-fold higher in case of CS-NLCs + PB loaded gel than that of naive CS gel and thereafter the release got reduced, which indicated the sustained release of CS from NLCs. The zone of inhibition of CS-NLCs + PB loaded gel was 0.5-fold, 0.2-fold and 0.54-fold higher than naive PB gel alone, naive CS gel alone and CS-PB gel combination, respectively. It indicated significantly higher antibacterial activity of CS-NLCs + PB loaded gel as that of any other treatment group.