# Gold Nanorods Enable Rapid and Label-Free SARS-CoV‑2 Detection through LAMP Assay

## TL;DR

Gold nanorods are used to quickly detect SARS-CoV-2 genetic material with high sensitivity and accuracy.

## Contribution

A rapid, label-free biosensing method for SARS-CoV-2 detection using AuNRs and DDLS with LAMP amplification.

## Key findings

- The biosensing approach reduces LAMP reaction time to 20 minutes.
- AuNR-based transducers enable direct detection of SARS-CoV-2 amplicons with high sensitivity.
- Clear discrimination between positive and negative samples was achieved using clinical specimens.

## Abstract

Nanoscale noble metals exhibit unique optical properties
due to
localized surface plasmon resonance (LSPR), which occurs within the
visible range of the electromagnetic spectrum. This property has facilitated
their extensive use as transducers in biosensor platforms. Among these,
gold nanoparticlesparticularly gold nanorods (AuNRs)have
gained significant attention owing to their superior plasmonic characteristics.
Their anisotropic shape generates two distinct plasmonic bands, enhancing
light absorption, scattering, and sensitivity to environmental changes.
Here, we present a biosensing approach for detecting the SARS-CoV-2
genetic material amplified via loop-mediated isothermal amplification
(LAMP), using AuNRs as transducers to generate dynamic light scattering
signals captured by a custom-built depolarized dynamic light scattering
(DDLS) apparatus. This strategy reduces the conventional LAMP reaction
time to 20 min and allows direct detection of target amplicons, representing
a substantial improvement over traditional indirect detection methods
that are often prone to false results. Clear discrimination between
negative and positive samples was achieved using both control reactions
and clinical specimens, demonstrating the potential of integrating
AuNR-based transducers with LAMP and DDLS into an efficient, rapid,
and highly sensitive diagnostic platform.