Ultra-low limit heparin detection based on 11-mercaptoundecanoic acid /chitosan functionalized and AuNPs enhanced...

Heparin is a sulfated glycosaminoglycan that is crucial for inhibiting coagulation and maintaining vascular blood flow. Among the existing detection methods, although electrochemical technology has the advantages of rapid detection and strong sample compatibility, it has limitations such as insufficient selectivity and susceptibility to environmental interference in stability. Nuclear magnetic resonance technology can accurately analyze molecular structures, but it is limited by complex sample processing, high equipment costs and large sample size requirements. Therefore, new detection technology with the advantages of operational convenience, rapid response and real-time detection applicability is needed.

We developed unlabeled gold nanoparticles (AuNPs) enhanced surface plasmon resonance (SPR) heparin sensor. Gold coating is applied on the surface of a tilted fiber Bragg grating (TFBG), and a 11-mercaptoundecanoic acid/chitosan (MUA/CS) functional film is modified on the gold film to form a heparin probe. Before detection, the tested heparin solution was functionalized with unlabeled AuNPs, which to can be aggregated on the probe surface to realize the enhancement of the SPR, enabling ultra-low concentration detection of heparin. The experimental results show that the sensor has a sensitivity of 0.29 dB/lg(g/mL) for heparin detection in the wide range of 10^-24 to 10^-2 g/mL, with a lower limit of detection (LOD) of 0.051 aM, which is more than one order of magnitude lower than that of the similar existing heparin sensors. Meanwhile, the TFBG-SPR sensor has a time response of ∼400 s for heparin detection.

This sensor demonstrates significant advantages such as label free detection and low detection limit compared to existing technologies. It also provides an innovative strategy for improving detection sensitivity and reducing the detection limit of similar biochemical substances.