Development of a novel SPRi carboxymethyl dextran biosensor for sensitive detection of ghrelin in biological samples

Ghrelin, as a hunger hormone and regulator responsible for appetite, is an important biomarker in metabolic research and potentially in clinical diagnostics. The aim of the study was to design and construct a new biosensor which uses a carboxymethyl dextran matrix and a streptavidin/biotin-based capture strategy for selective, label-free detection of ghrelin using SPRi (Surface Plasmon Resonance imaging) technique. Its selectivity, repeatability, and accuracy were verified and proved highly reliable. The analytical performance of the sensor was characterized by a low detection limit (17 pg/mL) and a quantification limit (52 pg/mL). Furthermore, it was tested on serum samples from patients with type 1 diabetes and a healthy control group. The results obtained were compared with the classic ELISA method, showing high consistency and repeatability of measurements. The proposed biosensor represents a "golden mean" between costly (e.g. reduction in analysis time and minimal sample consumption) and technically demanding analyses while still maintaining adequate sensitivity and specificity of the determination methods.