Development of a novel quantitative lateral flow assay for vancomycin for therapeutic drug monitoring.

Antibiotic optimisation through therapeutic drug monitoring (TDM) is a key strategy in tackling antimicrobial resistance. However, current quantification methods rely on laboratory-based equipment, delaying timely dose adjustments. We developed a novel point-of-care lateral flow assay (LFA) for the quantification of vancomycin in serum. Unlike conventional LFAs with a single test and control line, this assay incorporates two test lines: one for vancomycin binding and one for avidin capture of excess conjugate. Gold nanoparticles were conjugated to biotinylated bovine serum albumin-vancomycin, enabling competitive binding with anti-vancomycin antibodies and avidin capture. Signal ratios from smartphone-acquired images were quantified using an automated image analysis algorithm. Applied to vancomycin in serum, the LFA demonstrated a quantitative detection range of 2.88 to 45,000 ng/mL, with good accuracy, reproducibility, and high recovery in spiked samples. This approach offers a promising solution for decentralised, rapid TDM in clinical settings, especially where timely dose optimisation is critical.