Biopolymeric receptor for peptide recognition by molecular imprinting approach—Synthesis, characterization and application

• Development of a biocompatible zwitterionic hydrogel
• A series of chitosan-derived zwitterionic hydrogel samples
• Polymeric format is herein chosen for imprinting the dipeptide ‘carnosine’.
• An artificial receptor for dipeptide carnosine is designed, synthesized by molecular imprinting.
• Imprinted gel had a high affinity to carnosine in the presence of close structural analogues.

The present work is focused on the development of a biocompatible zwitterionic hydrogel for various applications in analytical chemistry. Biopolymer chitosan was derivatized to obtain a series of zwitterionic hydrogel samples. Free amino groups hanging on the biopolymeric chain were reacted with γ-butyrolactone to quaternize the N-centers of polymeric chain. N,N-methylene-bis-acrylamide acts as a crosslinker via Michael-type addition in the subsequent step and facilitated gelation of betainized chitosan. These biopolymeric hydrogel samples were fully characterized by FTIR, 1H NMR, 13C NMR spectra, SEM and XRD. Hydrogels were further characterized for their swelling behavior at varying parameters. The extent of swelling was perceived to be dictated by solvent composition such as pH, ionic strength and temperature.This valuable polymeric format is herein chosen to design an artificial receptor for dipeptide ‘carnosine’, which has adequate societal significance to be analytically determined, by molecular imprinting. Electrostatic interactions along with complementary H-bonding and other hydrophobic interactions inducing additional synergetic effect between the template (carnosine) and the imprinted polymer led to the formation of imprinted sites. The MIP was able to selectively and specifically take up carnosine from aqueous solution quantitatively. Thus prepared MIPs were characterized by FTIR spectroscopy, SEM providing evidence for the quality and quantity of imprinted gels. The binding studies showed that the MIP illustrated good recognition for carnosine as compared to non-imprinted polymers (NIPs). Detection limit was estimated as 3.3 μg mL− 1. Meanwhile, selectivity experiments demonstrated that imprinted gel had a high affinity to carnosine in the presence of close structural analogues (interferrants).

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