Synthesis by photopolymerization and the use of thin films of polymers with molecular prints for the molecular recognition of cephalosporins

Abstract

The conditions for obtaining thin MIP films unlimitedly soluble in water on the electrode sensor surface were studied. The process involved the immobilization of cephalosporins from aqueous solutions to the self-assembled γ-aminopropyltriethoxysilane layer through glutaraldehyde and photopolymerization of a mixture containing the initiator of the polymerization 2,2-azobis (isobutyrononitrile), functional and cross-monomers: methacrylic acid and ethylene glycol dimethacrylate. By the method of piezoquartz micro-weighting were estimated the coating mass after the MIP film formation, the desorption mass of cephalosporin molecules from it, and by the difference between them, the mass of the cephalosporin built into the MIP. Established that the use of a concentration of cefotoxin and cefritaxine of 0.5 mg/cm³ at the immobilization stage leads to the formation of a maximum number of molecular imprints on the film surface. Studied the influence of the polymerization mixture volume dosed to the electrode surface on the concentration of cephalosporins surface imprints. As a result of three cycles of cephalosporins sorption / desorption, was observed a decrease in the MIP mass with 1.5 μl of the polymerization mixture, and an increase in the mixture volume to 2.5-5 μl increased the stability of the MIP film. A comparison of the sorptive cefotaxime mass from a standard solution at concentrations of 20 μg/cm³ with triple antibiotic sorption on MIP films obtained with the application of 2.5 μl of the polymerization mixture showed that the mass of sorbed cefotaxime remains practically constant. Selected the composition of the regenerating solution: a solution of acetic acid and ethanol in water, taken in volume ratios of 1:6:100. Surface profiles obtained by atomic force microscopy of the MIP layer were compared before and after the sorption of cephalosporin and the NIP. Established the calibration functions equations of the piezoelectric sensor for the determination of cephalosporins (the correlation coefficient is 0.98 for ceftazidime and ceftriaxone and 0.99 for cefotaxime). Identified the ranges of the detected contents and the detection limits of antibiotics. Evaluated the values of the imprinting factor ΔF_MIP:ΔF_NIP, allowing to estimate the contribution to the sensor analytical signal of specific and nonspecific interactions. The piezoelectric MIP sensor was tested in the analysis of ceftazidime, ceftriaxone, cefotaxime in calf blood plasma.