Paper-based genetic assays with bioconjugated gold nanorods and an automated readout pipeline

Abstract

Paper-based biosensors featuring immunoconjugated gold nanoparticles have gained extraordinary momentum in recent times as the platform of choice in key cases of field applications, including the so-called rapid antigen tests for SARS-CoV-2. Here, we propose a revision of this format, one that may leverage on the most recent advances in materials science and data processing. In particular, we target an amplifiable DNA rather than a protein analyte, and we replace gold nanospheres with anisotropic nanorods, which are intrinsically brighter by a factor of ~ 10, and multiplexable. By comparison with a gold-standard method for dot-blot readout with digoxigenin, we show that gold nanorods entail much faster and easier processing, at the cost of a higher limit of detection (from below 1 to 10 ppm in the case of plasmid DNA containing a target transgene, in our current setup). In addition, we test a complete workflow to acquire and process photographs of dot-blot membranes with custom-made hardware and regression tools, as a strategy to gain more analytical sensitivity and potential for quantification. A leave-one-out approach for training and validation with as few as 36 sample instances already improves the limit of detection reached by the naked eye by a factor around 2. Taken together, we conjecture that the synergistic combination of new materials and innovative tools for data processing may bring the analytical sensitivity of paper-based biosensors to approach the level of lab-grade molecular tests.

Development of a method to diagnose endometrial cancer based on the AuNRs‐AntiVimentin optical probe

“…The AuNRs‐AntiVim was prepared according to the literature, and the Vim antibody was diluted 5000 times (Borri et al, 2022; Wang & Irudayaraj, 2008; Zhang et al, 2013). 3 mL of the prepared gold nanorods solution was centrifuged at 13,000 rpm for 3 min, and the solution was discarded.…”