Prednisolon Tayini için Yüzey Tanıma Bölgelerine Sahip Moleküler Baskılanmış Sensörlerin Geliştirilmesi

Abstract

In this thesis, molecularly imprinted optical sensors with surface recognition regions for prednisolone (PRD) determination have been prepared. Within the scope of this study, nanoparticles were prepared by two-phase mini-emulsion polymerization by changing amount of PRD, which is a template molecule, and the particles were attached to the gold chip surface of the surface plasmon resonance sensor with different techniques. Three differentially imprinted particles (PIN1, PIN2, and PIN3) and one non-imprinted particle (NIN) were first characterized by dimensional analysis (Zeta-sizer and STEM) and then structurally (FTIR and elemental analysis). After the chip surface has been modified with particles, the nanosensors were characterized by means of ellipsometer and contact angle measurements. Kinetic analyzes were performed for four sensors at pH 6.6 and 7.4 and Langmuir, Freundlich, Scathard and Langmuir-Freundlich isotherm models were applied to the data. As a result of the kinetic analyzes, the limit of detection for the PIN1, PIN2, PIN3 and NIN sensors at pH 6.6 were 5.1 ppb, 5.5 ppb, 6.9 ppb and 7.4 ppb, respectively, while the limit of quantifications were determined as 16.9 ppb, 18.2 ppb, 23.1 ppb and 24.2 ppb, respectively. The limit of detection at pH 7.4 was calculated as 10.7 ppb, 8.9 ppb, 13.7 ppb and 12.1 ppb in the same order, and the limit of quantification were calculated as 35.5 ppb, 29.7 ppb, 45.5 ppb and 40.2 ppb, respectively. Competition kinetic assays were performed by using 17-a-ethynyl estradiol (EEST) and estradiol (EST). Imprinted sensors labeled with PIN1, PIN2 and PIN3 codes were selected 1.195; 6.500 and 1.699 times more sensitive to the PRD than EEST when it is compared with non-imprinted NIN-encoded sensor, respectively, and these values were determined as 1.676; 7.857 and 2.037 times for EST at pH 6.6. At pH 7.4, the relative selectivity coefficients were calculated as 3.009; 10.556; 2.679 and 2.758; 14.778; 4.500 times for EEST and EST, respectively. The reusability studies have been applied to the sensor with the best results and 92.8 % recovery is achieved. The method was successfully applied to monitor PRD levels in body fluids (urine and plasma) as a naturel sample. Validation studies of the system were performed according to the standard procedure by high performance liquid chromatography (HPLC). Proposed SPR sensor method was in good agreement with those obtained by HPLC method.