Optical fiber SPR probe platform combined with oriented antibody optimized modification for ultrasensitive and portable detection of human thyroglobulin

Thyroglobulin (Tg) is an essential indicator for monitoring differentiated thyroid cancer. However, there are still significant challenges in achieving fast, accurate, and efficient point-of-care testing (POCT). This paper presented an optical fiber bioprobe platform technology based on the ultrasensitive sensing principle of surface plasmon resonance (SPR), aiming to achieve an efficient and precise immunoassay of Tg. The fiber probes were modified with Tg antibodies to form fiber Tg probes. After optimization of the oriented antibody modification, the detection sensitivity of fiber Tg probes increased by 3 times, facilitating one-step direct detection of μg-level sample concentrations such as thyroid tissue fluid samples. For ng-level sample concentrations such as blood samples, a two-step measurement method was used to amplify the surface load signal. Through Tg detection studies in different concentration ranges and background environments, our fiber Tg probes exhibited a sensitivity of 81.99 pm / (ng / mL) and a limit of detection of 1.4 ng / mL, and were able to complete ng-level detection in serum backgrounds. The fiber Tg probe holds immense potential in the diagnosis and postoperative monitoring of thyroid cancer. Additionally, being a miniature, disposable, reliable, and portable quantitative optical immunoassay tool, it can serve as a rapid detection instrument for various target proteins and pathogens by simply altering the modified antibody.