Caging of plumbagin on silver nanoparticles imparts selectivity and sensitivity to plumbagin for targeted cancer cell apoptosis.

Plumbagin is a nutraceutical with potent anti-cancer activity. However, the therapeutic efficacy of plumbagin is overshadowed by the lack of sensitivity and selectivity towards cancer cells. The present study evaluated the use of nano-biotechnological intervention to cage plumbagin in silver nanoparticles for selective targeting of its biological effects towards cancerous cells. Caging of plumbagin in silver nanoparticles imparted selectivity and sensitivity to plumbagin for selective killing of cancer cells by altering the redox signalling events in the cancer cells. The selectivity and sensitivity of plumbagin towards cancer cells was due to the cumulative expression of the properties of plumbagin and nanoparticles which specifically affected the differential cancer cell microenvironment by altering the pyruvate kinase activity that regulates the ROS challenge in cancerous cells. The positive surface charge of plumbagin caged silver nanoparticles (PCSN) aids in getting them targeted towards anionic cancerous cells due to the exposed terminal carboxyl group of sialic acid residues. Furthermore, we observed that the effective concentration of the drug required to induce apoptosis was brought down to 50% upon caging of plumbagin on silver nanoparticles. We observed no such effect with the individual compound alone. The results indicated that the physico-chemical and biochemical properties of plumbagin significantly changed after conjugation with nanomaterials that facilitated "adding-in" therapeutical values to plumbagin which would otherwise be overshadowed by its lack of sensitivity and selectivity towards cancer cells.