Development of L-proline imprinted nanofilm coated surface plasmon resonance sensors

Proline has become an important biomarker for the detection and identification of diseases. It has been documented in the literature that metabolic patients with esophageal cancer had significantly lower serum proline levels. In addition hyperprolinemia, a rare metabolic condition, occurs when the level of proline in the blood is elevated. Molecularly Imprinted Polymers (MIPs) are synthetic polymers that use a specific target molecule as a "template" and create recognition sites specific to this molecule in their structure. MIPs, can be used as recognition components in surface plasmon resonance (SPR) sensors. SPR biosensors provide rapid, sensitive, and economical detection of target biomolecules by measuring changes in the refractive index on or near a thin metal film. Furthermore, when combined with MIPs, the selectivity and sensitivity of the sensors can be significantly increased. In this study, aim was to synthesize L-proline imprinted nanofilms on the surface of gold SPR chip to selectively detect the L-proline molecule from human serum. Poly (2-hydroxyethyl methacrylate) (PHEMA)-based Pro-MIP and non-imprinted (NIP) SPR sensors were synthesized and characterized by scanning electron microscope images (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM) and contact angle measurements. According to SEM analysis results, it was observed that polymerization occurred homogeneously on the surface. Aqueous L-proline solutions at various concentrations were used in adsorption studies for the real-time detection of prolin and detection limit was obtained as 0,5 µg/mL. The SPR isotherm parameters were determined accordingly, and the results demonstrated that Pro-MIP SPR sensors were more compatible with the Langmuir isotherm model. Selectivity of the SPR sensor for L-prolin was evaluated in presence of competitor molecules L-histidine and L-phenylalanine. In selectivity studies, proline showed 6.4 and 7.5 times higher selectivity than the competing molecules histidine and phenylalanine, respectively. In addition, it was determined that Pro-MIP SPR sensors can be used up to 5 times without significant decrease in adsorption capacity. Outcomes showed that a biosensor was obtained that could determine L-proline in low detection limits, simultaneously. Keywords: L-proline, molecularly imprinted polymers, surface plasmon resonance sensors, nanofilm, cancer biomarker