Surface modified chitosan-silica nanocomposite porous thin film based multi-parametric optical glucose sensor

In this work, a multi-parametric optical sensor based on chitosan-silica nanocomposite (CSNC) porous thin film has been developed for effective detection of glucose in pathological range. The CSNC films were surface functionalized with Glucose Oxidase enzyme via Glutaraldehyde crosslinking chains for better attachment of enzyme molecules on thin film surface. FESEM and FTIR were performed for morphological and compositional characterisation of the composite films. Five interlinked optical parameters, i.e., transmittance (T), reflectance (R), internal scattering (IS), surface scattering (SS) and output power (OP) were measured simultaneously using image processing environment for cost efficiency of the system. Effect of surface functionalization on individual parameter response was studied. It was observed that without surface functionalization only two parameters change significantly, while surface functionalization enables all five parameters. For lower and higher glucose concentration (< 17 mM and > 17 mM), IS and SS were found to be maximum sensitive among the five parameters, respectively. Maximum sensitivity of 1.2 mM^-1 in IS and 1 mM^-1 in SS were observed for surface functionalized samples. The sensor showed good sensitivity, selectivity and reproducibility in the dynamic range of 3-30 mM and LOD of the sensor was found to be 0.76 mM. CSNC sensors were found suitable for single-time use and as mass production is possible with little amount of composite solution (250 sensors with just 10-ml composite solution), the sensor fabrication method is very much cost efficient. Image processing-based multi-parametric sensing is a novel field itself and detailed study of surface modified CSNC glucose sensors utilizing such sensing system is a unique work having potential to significantly contribute in the field of multi-parametric label-free optical biosensor research.