Electrospun Poly-ϵ-caprolactone/Poly-l-lysine (PCL/PLL) Nanofibers as an Emergent Material for the Preparation of Electrochemical Immunosensor to Detect Serum Amyloid A

Abstract

Serum amyloid (SAA), one of the acute-phase reactants, plays a significant role in acute and chronic inflammatory diseases. It is widely used in the clinical field as a biomarker of inflammation. Developing rapid and sensitive measurement systems is crucial to precisely detect the presence of SAA, even at very low levels. Therefore, in this study, we developed an electrochemical immunosensor using electrospun nanofibers (ESNFs) based on poly-ϵ-caprolactone (PCL) and poly-l-Lysine (PLL) as an immobilization matrix. ESNFs covered the surfaces of screen-printed carbon electrodes (SPCEs) for enhanced performance. The PCL/PLL ESNFs were characterized using water contact angle measurements, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy techniques. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and impedance spectroscopy (EIS) were employed to characterize the electrochemical behavior of the developed electrode surface. In conjunction with the analytical characterizations of the proposed immunosensor, linear range, limit of detection (LOD), interfering effect of some potential chemicals, and real sample applications were carried out. The sensor exhibited a working range and the linear range of 0.1-50 and 0.1-10 ng/mL with a calculated LOD of 0.061 ng/mL for SAA, respectively. Additionally, the sensor demonstrated advanced specificity, showing no response to the interfering species such as urea, glucose, insulin, and C-reactive protein. Validation of the sensor yielded excellent recovery for the artificial serum (100.04%), human real serum (103.32%), and artificial saliva (99.5%) samples containing 1 ng/mL SAA. Therefore, we believe that the sensor, with its high specificity, and sensitivity, can effectively contribute to the detection of SAA at low levels in biological fluids during clinical tests.