Amoxicillin imprinted surface plasmon resonance nanosensors

Antibiotics are a type of antimicrobial drug used in the treatment and prevention of bacterial infections. They may either kill or inhibit the growth of bacteria. AMOXicillin (AMOX) is also an antibiotic for the treatment of a number of bacterial infections, but antibiotic resistance is a serious public health concern shared by the animal health community. That's why the FDA and American Veterinary Medical Association to ensure the responsible use of antibiotics in animals that produce food. This study aims to investigate a technique for the antibiotic residue analysis that can detect a wide range of antibiotic residues directly in drinking milk by producing reliable and definitive results. Devices which convert the biological response to electrical signals are defined as ''Biosensors''. Biosensor containing biological elements and physicochemical transducers is a type of analytical device. Molecularly imprinted polymers were unified with the transducers through major developments in the field of biosensors and interactions between analyte and MIP can be converted into a processed signal. In this sense, surface plasmon resonance (SPR) based optical devices have a great potential. In this study, SPR based nanosensors are intended to prepare for the detection of AMOXicillin in milk by using molecular imprinting technique. For this purpose, first N-methacryloyl-(L)-glutamic acid (MAGA) monomer was synthesized, then to define the optimum ratio between template AMOX molecule and MAGA monomer, template molecules and MAGA monomer were mixed in different ratios and the optimum ratio was determined by using UV-visible region spectrophotometry. Nanosensor preparation studies were realized according to the optimized ratio conditions. Nanosensors are prepared in two stages with a micro-contact method by AMOX imprinted nanofilm and by attaching AMOX imprinted nanoparticles to the gold surface of the chip. For this specified purpose in the first stage, AMOX imprinted PHEMAGA (MIP) nanofilm was attached onto the allyl mercaptan modified gold chip surface by micro-contact method. In the second part of the study, to work in a targeted concentration range PHEMAGA (MIP) nanoparticles were synthesized by a two-phase mini-emulsion polymerization method. Then the prepared oil phase was slowly added to the first aqueous phase. In order to obtain mini-emulsion, the mixture was homogenized at 25 000 rpm by a homogenizer. After homogenization, the mixture was added to the PHASE II. Then, initiators, sodium bisulfite, and ammonium persulfate were added to the solution. Polymerization was continued for 24 h at 40°C. Besides this, for a control experiment, the non-imprinted PHEMAGA (NIP) nanoparticles were synthesized by applying same procedure with imprinted nanoparticles except the addition of template AMOX molecules. Size distribution of the prepared nanoparticles was characterized by zeta size measurements. SPR biosensors prepared by AMOX imprinted PHEMAGA (MIP) and non-imprinted PHEMAGA (NIP) nanofilms and nanoparticles then, characterized by FTIR-ATR, Atomic force microscope (AFM), Contact angle (CA), Ellipsometer measurements. To determine the kinetic and adsorption models of interactions between [PEDMALM-HSA] (MIP) nanofilm and nanoparticles attached to SPR nanosensor and AMOX solution, four different adsorption models named Scatchard, Langmuir, Freundlich, and Langmuir-Freundlich (LF) were employed. This study will contribute to the literature by comparing the advantages of the nanofilm attached nanosensor prepared by micro-contact method and nanoparticles attached nanosensor. Keywords: Surface plasmon resonance (SPR), Molecular imprinted polymer (MIP), Micro-contact, Nanoparticle, Amoxicillin.