Low fouling and pH-responsive poly(N-vinyl imidazole)/poly(ethylene glycol) methacrylate copolymer gels for colon targeted diclofenac sodium delivery

Abstract

Protein and cell adhesion onto drug delivery matrices interferes with the predesigned drug delivery profile to the targeted site. Antifouling surfaces are needed to overcome this problem and improve the effectiveness and efficiency of drug delivery systems. Copolymers of N-vinyl imidazole (NVI) with poly(ethylene glycol methacrylate) (PEGMA) were synthesized via free radical polymerization under cryogenic conditions as potential pH-responsive drug delivery systems resistant to protein and cell adhesion. FTIR spectroscopy, elemental analysis, thermal analysis (DSC), mechanical tests, contact angle, surface energy, and SEM analysis provide the physicochemical properties of the samples. Static adsorption/adhesion experiments show that the copolymer cryogels resist BSA adhesion. Furthermore, the copolymer cryogels demonstrate anti-cell adhesion behavior against colon colorectal carcinoma (HCT-116) cells. They are non-cytotoxic toward HDFa fibroblasts. Diclofenac sodium (DS) - loaded copolymer cryogels show pH-dependent sustained drug delivery. The release studies show a limited release in stomach pH (2.0). On the other hand, enhanced release is observed in pH 5.0 and pH 7.4 within 15 h. The quantities of diclofenac sodium released from the copolymer cryogels are sufficient to show anti-inflammatory activity.