Detection and size measurement of individual hemozoin nanocrystals in aquatic environment using a whispering gallery mode resonator

TL;DR

This paper demonstrates the first use of whispering gallery mode resonators to detect and measure the size of individual hemozoin nanocrystals in aquatic environments, with results validated against established methods.

Contribution

It introduces a novel application of mode splitting in WGM resonators for nanoparticle detection and size measurement in aquatic environments, specifically targeting biological nanocrystals.

Findings

Successful detection of single hemozoin nanocrystals in solution and air.

Size measurements agree with SEM and DLS results.

Comparison shows different sensing capabilities of mode regimes.

Abstract

We, for the first time, report the detection and the size measurement of single nanoparticles (i.e. polystyrene) in aquatic environment using mode splitting in a whispering gallery mode (WGM) optical resonator, namely a microtoroid resonator. Using this method we achieved detecting and measuring individual synthetic hemozoin nanocrystals, which are a hemoglobin degradation by-product of malarial parasites, dispersed in a solution or in air. The results of size measurement in solution and in air agree with each other and with those obtained using scanning electron microscope and dynamic light scattering. Moreover, we compare the sensing capabilities of the degenerate (single resonance) and non-degenerate (split mode, doublet) operation regimes of the WGM resonator.