Aptamer-procalcitonin-antibody sandwich on an interdigitated microelectrode biosensor for diagnosing septic arthritis

Septic arthritis is a joint inflammation caused by an infectious etiology, mainly bacterial but occasionally by viral, mycobacterial, fungal, and other pathogens. Septic arthritis is monoarticular, affecting large joints, such as the knees or hip, and possibly causing severe joint destruction. In order to improve treatment and speed up healing, it is helpful to diagnose septic arthritis early. Early identification of septic arthritis is to provide timely medication and increase the recovery rate. Procalcitonin (PCT) has been proven to be a reliable marker for septic arthritis and has demonstrated diagnostic usefulness in the identification of bacterial infections. Here, a PCT biosensor was developed on a silica nanoparticle (SiNP)-modified interdigitated microelectrode (IDME). SiNP was modified on IDME by attaching it to an amine-linker and COOH-ended aptamer through the amine. SiNP-modified electrode increased the aptamer immobilization and was saturated at 800 nM. On the aptamer immobilized surfaces, PCT was quantified at values as low as 0.1 ng/mL [y = 4.103x - 7.0337; R 2 = 0.9555] by using anti-PCT antibody as a detection probe. Furthermore, PCT-spiked serum was detected from 0.1 ng/mL without any interference, and the control experiments with CTxII, CRP, and complementary aptamer failed to change the current responses, indicating the selective and specific identification of PCT.