Development of macroscopically ordered liquid crystalline hydrogels from biopolymers with robust antibacterial activity for controlled drug delivery applications

Abstract

The design and development of self-assembled hydrogels with macroscopic ordering for the controlled delivery of drugs is an emerging area of research interest. The present work describes the development of a nanosilver entangled Schiff base hydrogel and demonstrates its application in the pH-dependent delivery of doxorubicin. The Schiff base hydrogel was synthesized from two biopolymers dextran and chitosan and silver nanoparticles were entrapped in the hydrogel network by an in situ condensation and reduction method. The incorporation of silver nanoparticles in the Schiff base hydrogel and the various non-covalent interactions present in it make the hydrogel rigid and macroscopically ordered. The self-assembled structures formed were studied by FT-IR, XRD, rheology analysis and microscopy techniques such as SEM, TEM and AFM. The presence of the mesogenic group –CN in the Schiff base imparts the liquid crystalline nature to the hydrogel. The anisotropic nature can be evidenced by polarized light microscopy. Doxorubicin is used as a model drug to study the anticancer properties of the ordered liquid crystalline hydrogel. The drug loading was studied at physiological and acidic pH. The in vitro degradation rate and drug release rate at pH 5.5 and pH 7.4 were also studied and it indicates the controlled release and pH dependent behavior of the hydrogel system. The presence of nanosilver in the hydrogel provides excellent antibacterial activity and it is screened by the agar well diffusion assay and the MIC and MBC values were measured and these results suggest its potential application as an antibacterial agent. In vitro cell viability studies were conducted by the MTT assay for the drug loaded hydrogels against A375 skin cancer cells and the results indicate that these hydrogels can effectively inhibit the growth of cancer cells. All these results suggest that the developed macroscopically ordered nanocomposite hydrogel can be used as a potential candidate for anticancer and antibacterial applications.