Development of a new method of template removal for molecularly imprinted polymers (MIPs) utilising biotechnology and its potential in optical sensing application

Molecularly imprinted polymers (MIPs) are polymers synthesised with specific affinity towards a molecule of interest. Template removal is a critical step in MIP preparation as it influences the effectiveness of the MIP. This work introduces a template removal step during the synthesis of MIPs where yeast is utilised as the template remover, signifying the biotechnology aspect. Glucose imprinted polymers (GIPs) in the form of films were synthesised in this study using PVA as the polymeric membrane. This newly developed method for synthesising MIPs indicated a more environmentally friendly option as harsh chemicals were omitted and long polymerisation hours were avoided. Optimisation of the GIPs was conducted in terms of film formation and template concentration. Various plots and binding models such as the Scatchard plot, bi-Langmuir and Freundlich models were used to investigate the adsorption kinetics of the GIP. It was found that the GIP acquired a heterogeneity index of 0.5181, indicating heterogeneity and comprised mainly of two distinct binding sites. From the analysis of the binding models, the two distinct binding sites have binding affinities of 252.41 and 87.3 at densities of 1266.92 mM g-1 and 0.84 mM g-1 respectively. The presence of high densities of binding sites with higher affinity towards the glucose template molecule indicated successful imprinting within the PVA film. The GIP was studied for use as a potential optical sensor by coating it on fluorescent carbon dots (CDs). Optimisation for the coating process was performed. The binding activity of glucose molecules into the GIP was reflected through the changes of fluorescence intensity of the CDs. This demonstrated that the CDs were coated with GIPs and the fluorescence was affected by the removal and rebinding of glucose template molecules. A range of glucose concentrations were tested on the system as part of quantifying the analytical potentials of the CDs coated GIP. A Stern-Volmer plot was plotted with the Ksv value of 51.943 and the limit of detection for the glucose was evaluated to be 4.09×10-5 M. This study has successfully demonstrated a new method of template removal from MIPs using biotechnology and also the use of the synthesised GIP as a potential optical sensor.