Smartphone-assisted detection of nucleic acids by light-harvesting FRET-based nanoprobe

Caterina Severi , Nina Melnychuk , Andrey S Klymchenko (1)

1 LBP - Laboratoire de Biophotonique et Pharmacologie - UMR 7213

Point-of-care assays for optical detection of biomolecular markers attract growing attention, because of their capacity to provide rapid and inexpensive diagnostics of cancer and infectious diseases. Here, we designed a nanoprobe for detection of nucleic acids compatible with a smartphone RGB camera. It is based on light-harvesting polymeric nanoparticles (NPs) encapsulating green fluorescent donor dyes that undergo efficient Förster Resonance Energy Transfer (FRET) to red fluorescent acceptor hybridized at the particle surface. Green-emitting NPs are based on rhodamine 110 and 6G dyes paired with bulky hydrophobic counterions, which prevent dye self-quenching and ensure efficient energy transfer. Their surface is functionalized with a capture DNA sequence for cancer marker survivin, hybridized with a short oligonucleotide bearing FRET acceptor ATTO647N. Obtained 40-nm poly(methyl methacrylate)-based NP probe, encapsulating octadecyl rhodamine 6G dyes with tetrakis(perfluoro-tert-butoxy)aluminate counterions (~6000 dyes per NP), and bearing 65 acceptors, shows efficient FRET with >20 % quantum yield and a signal amplification (antenna effect) of 25. It exhibits ratiometric response to the target DNA by FRET acceptor displacement and enables DNA detection in solution by fluorescence spectroscopy (limit of detection 3 pM) and on surfaces at the single-particle level using two-color fluorescence microscopy. Using a smartphone RGB camera, the nanoprobe response can be readily detected at 10 pM target in true color and in red-to-green ratio images. Thus, our FRET-based nanoparticle biosensor enables detection of nucleic acid targets using a smartphone coupled to an appropriate optical setup, opening the way to simple and inexpensive point-of-care assays.

Mots clés: Smartphone-based detection; Detection of nucleic acids; Fluorescence microscopy; Polymeric nanoparticles; Nanoantenna; Point-of-care diagnostics

Domaines: Chimie

Caterina Severi, Nina Melnychuk, Andrey S Klymchenko. Smartphone-assisted detection of nucleic acids by light-harvesting FRET-based nanoprobe. Biosensors and Bioelectronics, 2020, 168, pp.112515. ⟨10.1016/j.bios.2020.112515⟩. ⟨hal-02977449⟩