Impact of metal crystallinity-related morphologies on the sensing performance of plasmonic nanohole arrays

Multiplexed Profiling of Extracellular Vesicles for Biomarker Development

Extracellular vesicles (EVs) are cell-derived membranous particles that play a crucial role in molecular trafficking, intercellular transport and the egress of unwanted proteins. They have been implicated in many diseases including cancer and neurodegeneration. EVs are detected in all bodily fluids, and their protein and nucleic acid content offers a means of assessing the status of the cells from which they originated. As such, they provide opportunities in biomarker discovery for diagnosis, prognosis or the stratification of diseases as well as an objective monitoring of therapies. The simultaneous assaying of multiple EV-derived markers will be required for an impactful practical application, and multiplexing platforms have evolved with the potential to achieve this. Herein, we provide a comprehensive overview of the currently available multiplexing platforms for EV analysis, with a primary focus on miniaturized and integrated devices that offer potential step changes in analytical power, throughput and consistency.

Extinction-to-Absorption Ratio for Sensitive Determination of the Size and Dielectric Function of Gold Nanoparticles

Gold nanoparticles (AuNPs) have become an essential tool for a variety of fields across the biological, physical, and chemical sciences. The characterization of AuNPs by UV-vis spectroscopy is simple and commonly used but remains prone to error because of size and shape polydispersity and uncertainties in the dielectric function. We here propose and demonstrate a method to significantly improve this routine characterization technique by measuring not only the extinction but also the absorption spectrum. Specifically, we show that by considering the ratio of the extinction to absorption spectra, denoted η, we are able to determine the volume of AuNPs with a significant increase in accuracy compared to the UV-vis extinction method. We also prove an important property of η: it is independent of particle shape within the quasi-static/dipolar approximation, typically for particle sizes up to 100 nm. This shape independence results in very strong constraints for the theoretical predictions to agree with the experiments. We show that the spectral shape of η can therefore be used to discriminate between different proposed data sets for the dielectric function of gold, a long-standing challenge in plasmonics research.