Surface functionalization of porous chitosan microsphere with silver nanoparticle and carbon dot

Abstract

Abstract Porous microspheres have enormous specific surface area due to the presence of micropores. This makes them suitable for all applications that involves surface adsorption e.g. chromatographic separation of biomolecules, catalytic reactions and drug delivery. The surface property may further be tuned up by functionalization of microsphere surface with different nanoparticles like silver nanoparticle and carbon dot (CD). In this study porous chitosan microsphere (PCM) was synthesized by ‘phase inversion of emulsion’ technique. Silver nanoparticle (AgNP) was synthesized, insitu during the process of surface modification, using silver nitrate solution. CD was synthesized by solvothermal method using urea and EDTA. PCM, AgNP and CD were of ∼9 μm, ∼27 nm and ∼14 nm diameter, respectively. From FTIR study it was confirmed that the amino group of chitosan backbone was responsible for reduction of Ag+ ion to Ag° species which were clustered as AgNP and attached to the surface of PCM. The same amino group of chitosan molecule was also responsible for conjugation of CD to the microparticle surface. The optimized AgNP functionalized PCM had 5.36 × 1011 AgNP per mg dried mass. The release of AgNP was triggered at pH ≤ 4.5. The CD functionalized PCM had 56.82 ± 2.8 % conjugation efficiency and 7.83 ± 1.7 % quantum yield with respect to quinine sulphate.