Green synthesis of molecularly tailored chitosan-based gold and silver nanocomposite and their application in selective recognition of ciprofloxacin

Herein, a study on the chitosan-amalgamated gold nanoparticles (AuNPs)- and silver nanoparticles (AgNPs)-based molecularly imprinted polymer (MIP) film and its application to recognize/remove ciprofloxacin (CIP) antibiotic in real samples is reported. The pomegranate peel at pH 8 is used for the reduction of silver nitrate solution to form AgNPs, whereas chitosan itself is used for the reduction of gold chloride solution to form AuNPs. The size of the synthesized AgNPs and AuNPs is in the range 30–45 and 45–50 nm, respectively, which is determined by dynamic light scattering (DLS). Further, the synthesized nanoparticles (NPs) are used to prepare MIP film. The molecularly tailored chitosan-based nanocomposite is used as a functional biopolymer to enhance the adsorption capacity and surface area of MIP film. The properties of synthesized chitosan-based AuNPs- and chitosan-based AgNPs-MIP composite (Chi@AuMIP and Chi@AgMIP) exhibited much higher adsorption capacity than non-imprinted polymer (NIP). The results revealed that the theoretical equilibrium constant (K_L) and maximum adsorption capacity (Q_max) found by the Langmuir model are 12.2 and 20.48 mg g⁻¹ for Chi@AuMIP and 18.31 and 34.13 mg g⁻¹ for Chi@AgMIP, respectively. The recovery percentage of CIP for Chi@AuMIP and Chi@AgMIP is 98 and 80%, respectively. The selectivity experiment data suggest maximum adsorption capacity for targeted molecule (CIP) by the MIP as compared to analogs of template molecule. MIP showed relative potential selectivity and good recovery percentage for CIP in real samples as well.