Exploiting Electrostatic Interaction for Highly Sensitive Detection of Tumor-Derived Extracellular Vesicles by an Electrokinetic Sensor.

Siddharth Sourabh Sahu,Rolf Lewensohn,Apurba Dev,Amelie Eriksson Karlström,Kristina Viktorsson,Ábel Nagy,Jan Linnros,Petra Hååg,Sara Cavallaro

doi:10.1021/acsami.1c13192

Abstract

We present an approach to improve the detection sensitivity of a streaming current-based biosensor for membrane protein profiling of small extracellular vesicles (sEVs). The experimental approach, supported by theoretical investigation, exploits electrostatic charge contrast between the sensor surface and target analytes to enhance the detection sensitivity. We first demonstrate the feasibility of the approach using different chemical functionalization schemes to modulate the zeta potential of the sensor surface in a range −16.0 to −32.8 mV. Thereafter, we examine the sensitivity of the sensor surface across this range of zeta potential to determine the optimal functionalization scheme. The limit of detection (LOD) varied by 2 orders of magnitude across this range, reaching a value of 4.9 × 106 particles/mL for the best performing surface for CD9. We then used the optimized surface to profile CD9, EGFR, and PD-L1 surface proteins of sEVs derived from non-small cell lung cancer (NSCLC) cell-line H1975, before and after treatment with EGFR tyrosine kinase inhibitors, as well as sEVs derived from pleural effusion fluid of NSCLC adenocarcinoma patients. Our results show the feasibility to monitor CD9, EGFR, and PD-L1 expression on the sEV surface, illustrating a good prospect of the method for clinical application.

Highlights

Surface-based biosensors have received a lot of interest for developing highly sensitive, multiplexed, and lab-on chip compatible biosensors.[1−3] A primary design consideration when developing such a sensor is its sensitivity, which has motivated intense research interest
We investigated the influence of charge contrast as a strategy to enhance the detection sensitivity of small extracellular vesicles (sEVs)’ surface proteins. sEVs are a heterogeneous group of lipidbilayer nanovesicles released by all cell types
The detection sensitivity of the assay was tested by profiling surface proteins of sEVs isolated from the cell culture media of a non-small cell lung cancer (NSCLC) cell line

Summary

Introduction

Surface-based biosensors have received a lot of interest for developing highly sensitive, multiplexed, and lab-on chip compatible biosensors.[1−3] A primary design consideration when developing such a sensor is its sensitivity, which has motivated intense research interest. Since the response of such a sensor is proportional to the surface coverage of the analyte, a common strategy for enhanced sensitivity has been increasing the surface concentration of analytes by improving their mass transport rate.[4,5] Another strategy has been to exploit the nature of the sensing principle to amplify the signal transduction, e.g., surface engineering,[6,7] electrode design,[8,9] and so on In this context, the chemical surface functionalization, used in most affinity-based biosensors, may be exploited for an enhanced sensitivity. Given that such chemical functionalization drastically changes the physical and electrical properties of the interface layer, their influence on the sensor performance requires systematic investigation

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Discussion

Conclusion