Site specific drug delivery with desired therapeutic effect still remains challenging task due to suboptimal release, tissue toxicity, low selectivity and meager therapeutic efficacy in skin cancers. The aim of the current study was to fabricate pH responsive, self-assembled, chemically cross-linked biodegradable chitosan nanogel loaded with bleomycin to target the dermal area of the skin. The nanogel synthesized by ion gelation technique and was characterized for drug loading, swelling and thermal stability followed by in vitro analysis. HaCaT (Human Keratinocyte cell) and HDF (Human dermal fibroblast) cell line were used for the biocompatibility and cytocompatibility evaluation prior to the hemolysis assay and coagulation assessment. The nanogel had a size range of 150nm as determined by TEM and DLS. The nanogel possessed optimum thermal stability as analyzed by thermogravimetry (TG) and differential thermal analysis (DTA). Biodegradation was confirmed by lysozyme enzyme degradation assays. The drug entrapment efficacy was about 55% in the swollen state. The In vitro drug release profile revealed sustained release pattern. The hemolysis of 2.39% and prothrombin time (PT) and activated partial thromboplastin time (APTT) of 12.9 and 31s revealed the biocompatibility of nanogels. The cell uptake and localization profile was validated by fluorescence and confocal microscopy using HDF and HaCaT cell lines. Finally, the MTT assay demonstrated the cytocompatibility of nanogels. In conclusion, the present findings suggest that biodegradable chitosan nanogels with stimuli responsive nature can release the anticancer drug cargo in a sustained and controlled manner and offer promising potentials for treating skin cancers.

Statement of significance: Drug delivery to the targeted site is a major challenge in clinical medicine. The newly constructed pH responsive biodegradable nanogel consisting of bleomycin revealed pH triggered drug release in a sustained manner to the dermal area offering novel approach against skin cancer. The nanogel system is biodegradable in nature possessing high drug entrapment efficiency and offers patient compliance with biocompatible and cytocompatible characteristics. This nanogel system can thus be highly useful for delivery of anticancer drugs to the skin in a controlled and sustained manner.