Comparison and Analysis of Polymer-Functionalized Carbon Nanotubes for Enhancement of the Quantitative Detection of Procalcitonin Levels in Human Plasma

Procalcitonin (PCT) is one of the core biomarkers for the body’s systemic inflammatory response that is expressed uniformly in several organ tissues. PCT concentration levels rise significantly reaching the highest peak within 48 h after the bacterial infection starts. In this study, we evaluated different polymer-functionalized carbon nanotubes (CNTs) to enhance the performance of a sensing platform for the rapid detection of PCT over a large physiological range. CNTs were treated with polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and poly(L-arginine) P(Arg) to improve the nanostructures while promoting stability and reducing non-specific interaction. Different morphology analyses were performed to investigate the properties of the polymer-functionalized CNTs and compared them with the pristine material. Screen-printed carbon electrode (SPCE) sensors were modified with the three proposed nanocomposites and electrical characterization are performed. Afterward, the PCT antibody (100 ng/ml) is immobilized on the working electrodes before the electrochemical measurements with the analytes. Differential pulse voltammetry (DPV) responses were measured to quantify the PCT (27.43–20,000 pg/ml) in buffer solution and human plasma samples. CNT-PVP and CNT-P(Arg) electrodes presented a high correlation between the current peaks and the concentration of PCT. Subsequently, an interference study was carried out with inflammatory-related biomarkers that could cause a false positive response, the variation of the signal current was less than 3%. The SPCE devices also went through validation with the “gold-standard” laboratory method to verify the agreement with the proposed method. This study regarding the optimization of the CNTs is just the first part of our final target regarding a multiplexed point-of-care device using a small volume of the blood sample to provide a rapid diagnostic regarding inflammatory response.