A portable optical detection system for rapid quantification of two rheumatoid arthritis biomarkers.

Background: Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes joint damage and progressive destruction of adjacent cartilage and bones. Quick and accurate detection of rheumatoid factors (RF) and anti-cyclic citrullinated peptide antibodies (anti-CCP) in serum is effective in diagnosing RA and preventing its progression. However, current methods for detecting these two biomarkers are costly, time-consuming, labor-intensive, and require specialized equipment. To address these limitations, a new microfluidic chip was developed to automatically conduct the dual-RA biomarker detection assay.

Results: The integrated chip, which was equipped with micropumps, microvalves, and micromixers, was positioned underneath an optical detection module composed of a light-emitting diode, optical filters, condenser lenses, and a silicon photomultiplier to quantify the fluorescence signals of magnetic bead-bound analytes in two separate micro-chambers. The dual-target assay required only 5 μL of serum and took only 100 min to complete, accurately measuring RF and anti-CCP at concentrations ranging from 0.8 to 106.0 IU/mL and 6.0-59.0 U/mL, respectively. Compared with the gold standard, the accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of the developed on-chip assays were 95.5 %, 94.4 %, 100.0 %, 100.0 %, 80.0 % for both RF and anti-CCP detection with 30 clinical samples.

Significance: With its compact size of only 350 mm × 238 mm x 153 mm and low volumes of samples/reagents required, this system shows promise for point-of-care testing. The compact size, low sample volume requirement, and high performance of the developed system could significantly improve RA management and patient outcomes by providing rapid and accurate diagnostics in clinical settings.