Preparation and applications of aptamer-based electrochemical biosensors for the sensitive and selective determination of lysozyme

In this thesis, an electrochemical biosensor based on MIP-Apt was developed for the sensitive and selective determination of lysozyme (Lyz), a food allergen. Lyz is used in the food industry as a thinning and antibacterial agent. Lyz is an allergen that poses a risk to susceptible individuals. It is also used as a biomarker in the diagnosis of many diseases. Within the scope of this thesis, the determination of Lyz allergen, which has an important place in both the food industry and the medical field, was made with screen printed graphic electrodes (AuNP/GO/SPE) modified with graphene oxide (GO) and gold nanoparticle (AuNP). The advantages of both aptamer (Apt) biocomponent and molecular imprinted polymer (MIP) technology were utilized in the prepared biosensor. Fe(CN)63-/4- redox probe was used in all measurements made with differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) on the obtained MIP-Apt/AuNP/GO/SPE sensor surface. Surface characterization was performed using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), CV, DPV and EIS methods. Lyz determination was carried out with the developed sensor. Under appropriate conditions, the linear working range was determined as 0.001-100 pM, the limit of detection (LOD) of 0.00367 pM, and the lower limit of detection (LOQ) of 0.012 pM. The selectivity, reproducibility, reproducibility and storage stability parameters of the biosensor were investigated. In the applications made on real samples, sour cherry juice, mixed fruit juice and red wine samples from the local market were used and the % recovery values were calculated.