Non enzymatic colorimetric detection of glucose using cyanophenyl boronic acid included beta-cyclodextrin stabilized gold nanoparticles

The selective recognition and estimation of glucose in biological fluids is important for the management of diabetes. Many non enzymatic methods have emerged to address the limitations of in use enzymatic approaches. Still, new techniques have been designed, considering the high demand for user friendly and cost effective methods. In this context, a colorimetric assay by the naked eye is widely appreciated as a simple protocol adaptable to the rural populations of third world countries. Herein we have adopted a green approach for the fabrication of a novel non-enzymatic glucose sensing method based on the inclusion of 4-cyanophenyl boronic acid (CPBA) with beta-cyclodextrin (beta-CD) stabilized gold nanoparticles (GNP). While CPBA has a good selectivity towards glucose, its solubility is low in aqueous media and this issue is taken care of by b-CD. The three component system is synthesized by a tandem one pot method and used as such for the selective and sensitive detection of glucose in an aqueous medium. We observed a gradual shift of the plasmon absorption peak and an observable color change from red to blue with the concentration of glucose. The concentration dependant color change was attributed to glucose mediated aggregation of the probes as revealed by the TEM analysis. The applicability of the method to a real biological matrix was evaluated by testing with human blood serum in the concentration range 1-20 mM. This sensing methodology, based on chemicals already available in the market and dodging complex chemistry, can be adapted for routine glucose estimation.