(Digital Presentation) A Microfluidic Approach for Direct Immobilization of Extracellular Vesicles on Gold Nanoislands for Efficient Detection Using Localized Surface Plasmon Resonance

Abstract

Extracellular vesicles (EVs) are crucial for intercellular communication and are potential biomarkers for cancer diagnosis. To improve the detection of EVs, we have developed a platform that uses an ultra-thin film of gold to form gold nanoislands. This platform allows for the direct immobilization of EVs onto the gold nanoislands, using a simple microfluidic device. Detection of the EVs is based on the Localized Surface Plasmon Resonance (LSPR) method. With this innovative approach, we aim to enhance the accuracy and efficiency of EV detection, which could ultimately lead to faster detection and therefore the possibility of an early-stage diagnosis of cancer.Gold nanoparticles are deposited on glass substrates using physical vapor deposition to create an ultra-thin layer of gold. Annealing the nanoparticle film forms gold nano-islands, which are drops with varying shapes and sizes from solid dewetting. A PDMS microfluidic device with a tapered channel of 200-micron depth and a 4mm diameter collection chamber bonded to gold-coated substrates is used to detect EVs from MCF7. The EVs flow through the channel at a rate of 10 µL/min, and the LSPR spectrum of the gold nanoislands is measured before and after EV immobilization. Changes in the refractive index of the surrounding medium due to the presence of EVs cause a shift in the Au LSPR band, which can be used to detect EVs.In this study, we will utilize extracellular vesicles (EVs) obtained from a breast cancer cell line (MCF7) that had been grown in a small bioreactor. A simple microfluidic device will be designed and fabricated to evaluate the Localized Surface Plasmon Resonance (LSPR) shift of the gold plasmon band for different EV concentrations. The microfluidic device was chosen due to its high reproducibility, sensitivity, and ability to work with small amounts of EVs. To understand the sensitivity of this platform, a calibration curve will be plotted and compared with the results of other platforms that we have previously studied. To validate the LSPR detection using the microfluidic device, the eluted exosomes from the device will be characterized using TRPS and FESEM techniques.Overall, our findings will demonstrate the potential of utilizing EVs and LSPR-based microfluidic devices as a promising tool for the detection of EVs and further clinical analysis for cancer diagnosis.