Sensitive Electrochemical Analysis of Hydroxyproline in Achilles Tendon Collagen and Human Urine

Abstract

L-hydroxyproline (Hyp) is one of the significant amino acids present in connective tissue proteins such as collagen, elastin, and gelatin. The quantitative analysis of Hyp levels in bodily fluids is critical to assist with diagnosing diseases and early treatments. In the present study, for the first time, we report on a facile electrochemical method for the detection of Hyp using gold nanoparticles (AuNPs), which were electrochemically deposited on a glassy carbon electrode (GCE). The electrochemical behavior of the AuNPs/GCE for the oxidation of Hyp was examined using cyclic voltammetry, demonstrating higher electrocatalytic activity in contrast to GCE and bulk Au electrodes. Additionally, the mechanism for the electrochemical oxidation of Hyp was investigated using in situ Fourier transform infrared (FT-IR) spectroscopy. Moreover, the electrochemical sensing performance of the AuNPs was investigated using differential pulse voltammetry (DPV), exhibiting a low limit of detection (0.026 mM) and high sensitivity (8.5 μA (mM cm2)−1). The interference of other amino acids present in collagen and urine has been further tested, demonstrating high selectivity and good reproducibility. The novel electrochemical sensing approach described in the present study may lead to a facile non-enzymatic technique for the sensitive detection of Hyp, a significant biomarker.