On-chip screening of SARS-CoV-2 cDNA by LAMP-integrated rotational diffusometry.

The unprecedented pandemic has raised the demand for prompt, precise, and large-scale virus detection techniques to control the transmission of contagious illnesses. In this study, a loop-mediated isothermal amplification (LAMP) based on-chip platform was developed to address this challenge using rotational diffusometry and functionalized Janus particles. A recombinant plasmid containing a cDNA sequence of the SARS-CoV-2 non-structural protein 2 (nsp2) gene was employed here as a proof-of-concept for COVID-19 detection. Specifically, designed primers and the functionalized Janus particles were simultaneously loaded on a microfluidic chip to perform the LAMP reaction on a hot plate. The optimal Janus particle concentrations for diffusometric analysis were thoroughly validated, and the performance of the on-chip LAMP reaction was assessed using thermal image analysis. Utilization of the highly sensitive rotational diffusometry achieved a limit of detection of 1 pg/μL in just 10 min with a sample volume of 20 μL. Our method delivered a tenfold higher sensitivity than the conventional method by utilizing only half of its usual required time. Overall, this study proposes a potential nucleic acid (NA) amplification device to aid the rapid diagnosis of various diseases by modifying the primers for different target genes. A sensitive biosensing technique utilizing functionalized Janus particles-enabled rotational diffusometry on a microfluidic chip in combination with LAMP, that detects SARS-CoV-2 cDNA from a recombinant plasmid in 10 min with significant changes in particle rotation due to isothermal amplification of the nucleic acids. [Display omitted] • Diffusometric sensor enabled by Janus particles in combination with isothermal amplification. • Detection of SARS-CoV-2 nsp2 cDNA in a microfluidic chip. • Rapid screening in just 10 min. • Limit of detection 1 pg/μL. • Tenfold higher in sensitivity and twofold faster than the conventional method. [ABSTRACT FROM AUTHOR]