Articolo in rivista, 2022, ENG, 10.1038/s41598-022-10227-7

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

Claudia Borri, Sonia Centi, Sofia Chioccioli, Patrizia Bogani, Filippo Micheletti, Marco Gai, Paolo Grandi, Serena Laschi, Francesco Tona, Andrea Barucci, Nicola Zoppetti, Roberto Pini, Fulvio Ratto

Istituto di Fisica Applicata "Nello Carrara", Consiglio Nazionale delle Ricerche, 50019 Sesto Fiorentino, FI, Italy. Dipartimento di Biologia, Università degli Studi di Firenze, 50019 Sesto Fiorentino, FI, Italy. Laboratori Victoria S.R.L, 51100 Pistoia, Italy. Ecobioservices & Researches S.R.L, 50019 Sesto Fiorentino, FI, Italy.

Paper-based biosensors featuring immunoconjugated gold nanoparticles have gained extraordinary momentum in recent times as the platform of choice in key cases of feld 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 amplifable 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 workfow to acquire and process photographs of dot-blot membranes with custommade hardware and regression tools, as a strategy to gain more analytical sensitivity and potential for quantifcation. 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.

Scientific reports (Nature Publishing Group) 12

Keywords

Gold nanorods, rolC gene, dot-blot assay, standardized photography, linear regression

CNR authors

Borri Claudia, Zoppetti Nicola, Ratto Fulvio, Barucci Andrea, Pini Roberto, Gai Marco, Centi Sonia, Micheletti Filippo

CNR institutes

IFAC – Istituto di fisica applicata "Nello Carrara"