Molecularly imprinted poly(methacrylic acid) based QCM biosensor for selective determination of L-tryptophan

Abstract In the present work, molecularly imprinted polymer (MIP) for L-tryptophan amino acid was synthesized using bulk polymerization method and a highly selective and sensitive biosensing method for the amino acid was developed using quartz crystal microbalance (QCM) biosensor. L-tryptophan amino acid was successfully imprinted within poly(methacrylic acid) (PMAA) matrix and the same is confirmed through Fourier infrared spectroscopy (FTIR). The dynamic adsorption and Scatchard analysis were used to understand the effect of various imprinting parameters on the final structures. The molecularly imprinted polymer sample with 10 mmol of ethylene glycol dimethacrylate (EGDMA) crosslinker exhibited a high adsorption about 12 mg/g towards L-tryptophan. The imprinted structures were also studied using scanning electron and atomic force microscope techniques. Further, the optimized MIP pre-polymer solution has coated on QCM electrode surface and sensing studies was conducted. The limit of detection was determined as 0.73 ng/mL. Additional studies on selectivity using its structural analogous such as D-tryptophan and ascorbic acid, the MIP modified QCM biosensor exhibited respective higher selectivity coefficients towards L-tryptophan about 7.5 and 12. Further, the proposed MIP-QCM sensor was successfully applied to the determination of Tryptophan in real sample analysis such as food and urine samples with excellent recoveries ranging (97-104%).