# Experimental plasmonic sensing of malaria using an aluminum metasurface

## TL;DR

Researchers developed a new optical biosensor using aluminum nanoholes to detect a malaria biomarker with high sensitivity and low cost.

## Contribution

A novel aluminum metasurface-based biosensor for label-free detection of pfLDH in the visible spectrum is introduced.

## Key findings

- The biosensor achieves a spectral sensitivity of 360 nm per RIU.
- The limit of detection is 1.3 nM (45.6 ng mL−1) for pfLDH.
- The sensor operates in the visible range and is suitable for label-free malaria diagnosis.

## Abstract

A wide range of methods currently exist for testing the presence of malaria, each with its own advantages and disadvantages. New technologies are urgently needed to develop more effective diagnosis tools to fight and eradicate malaria. Optical biosensors that employ surface plasmon resonance (SPR) techniques are a promising category of devices for detecting malaria biomarkers. One such biomarker is plasmodium lactate dehydrogenase (pLDH), a protein produced during the life cycle of the malaria parasite, which is a metabolic enzyme found in all plasmodium species, including the most widespread falciparum. This work reports on the design, probing, and experimental performance of an optical biosensor for detecting pLDH based on SPR and extraordinary optical transmission. The biosensor is composed of an aluminum metasurface made from an array of nanoholes. The sensor operates in the visible spectral region and achieves label-free sensing of plasmodium falciparum LDH (pfLDH) spiked in phosphate-buffered saline. The sensor has a spectral sensitivity of 360 nm per RIU and an LOD of 1.3 nM, equivalent to 45.6 ng mL−1 of pfLDH. This type of optical biosensor may offer a cost-effective and high sensitivity method for active infection diagnosis.

We design and experimentally demonstrate a cost-effective aluminum nanohole-array SPR biosensor operating in the visible range for label-free detection of the malaria biomarker plasmodium falciparum lactate dehydrogenase (pfLDH).