Preparation of pH-sensitive nanogels bioconjugated with shark antibodies (VNAR) for targeted drug delivery with potential applications in colon cancer therapies.

Cancer is the second leading cause of death worldwide. To combat this disease, novel and specialized therapeutic systems are urgently needed. This is the first study to explore a system that combines shark variable domain (Fv) of new antigen receptor (VNAR) antibodies (hereinafter VNARs), PEGylated nanogels (pH-sensitive poly(N,N-diethylaminoethyl methacrylate, PDEAEM), and the anticancer drug 5-fluorouracil (5-FU) to explore its potential applications in colon cancer therapies. Nanogels were functionalized in a scalable reaction with an N-hydroxysuccinimide (NHS)-terminated polyethylene glycol derivative and bioconjugated with shark antibodies. Dynamic light scattering measurements indicated the presence of monodispersed nanogels (74 to 236 nm). All systems maintained the pH-sensitive capacity to increase in size as pH decreased. This has direct implications for the release kinetics of 5-FU, which was released faster at pH 5 than at pH 7.4. After bioconjugation, the ELISA results indicated VNAR presence and carcinoembryonic antigen (CEA) recognition. In vitro evaluations of HCT-116 colon cancer cells indicated that functionalized empty nanogels are not cytotoxic and when loaded with 5-FU, the cytotoxic effect of the drug is preserved. A 15% reduction in cell viability was observed after two hours of contact with bioconjugated nanogels when compared to what was observed with non-bioconjugated nanogels. The prepared nanogel system shows potential as an effective and site-specific nanocarrier with promising applications in in vivo studies of colon cancer therapies.