A Dual-Aptamer Sandwich Assay by Detection of C-Reactive Protein in Synovial Fluid on an Integrated Microfluidic System for Diagnosis of Periprosthetic Joint Infection

Abstract

Diagnosing periprosthetic joint infection (PJI) in equivocal cases is always challenging. Synovial fluid (SF) C-reactive protein (CRP) levels have been reported as a surrogate to improve the diagnosis accuracy. This study reported a new integrated microfluidic system (IMS) designed to detect SF-CRP at a dynamic range of 1-50 mg/L. The novel, magnetic bead-based, dual-aptamer assay with two CRP-specific aptamers, St1 and St2, enabled rapid and accurate CRP detection. This represents the first attempt to automatically perform the CRP dual-aptamer assay on a microfluidic chip quantifying CRP in SF with optical signals. CRP concentrations in fourteen clinical samples were accurately quantified by using the dual-aptamer assay on the developed IMS in an automatic format, suggesting the assay’s potential as a reliable diagnostic tool for SF-CRP detection and may serve as an armamentarium for PJI diagnosis. Notably, the assay was deemed superior to traditional enzyme-linked immunosorbent assay (ELISA) because it consumes a smaller amount of sample (only 40 μL), requires fewer reagents (only 50 μL of secondary detection aptamer and horseradish peroxidase), and provides quicker results (~2 hours).

Keywords: Aptamer, Bead-based assay, C-reactive protein, Microfluidics, Molecular diagnostics, Periprosthetic joint infection