Use of Surface-Enhanced Raman Scattering (SERS) Probes to Detect Fatty Acid Receptor Activity in a Microfluidic Device.

Han Zhang,Timothy Gilbertson,Lifu Xiao,Anhong Zhou,Wei Zhang,Yan Liu

doi:10.3390/s19071663

Abstract

In this study, 4-mercaptobenzoic acid (MBA)-Au nanorods conjugated with a GPR120 antibody were developed as a highly sensitive surface-enhanced Raman spectroscopy (SERS) probe, and were applied to detect the interaction of fatty acids (FA) and their cognate receptor, GPR120, on the surface of human embryonic kidney cells (HEK293-GPRR120) cultured in a polydimethylsiloxane (PDMS) microfluidic device. Importantly, the two dominant characteristic SERS peaks of the Raman reporter molecule MBA, 1078 cm−1 and 1581 cm−1, do not overlap with the main Raman peaks from the PDMS substrate when the appropriate spectral scanning range is selected, which effectively avoided the interference from the PDMS background signals. The proposed microfluidic device consisted of two parts, that is, the concentration gradient generator (CGG) and the cell culture well array. The CGG part was fabricated to deliver five concentrations of FA simultaneously. A high aspect ratio well structure was designed to address the problem of HEK cells vulnerable to shear flow. The results showed a positive correlation between the SERS peak intensity and the FA concentrations. This work, for the first time, achieved the simultaneous monitoring of the Raman spectra of cells and the responses of the receptor in the cells upon the addition of fatty acid. The development of this method also provides a platform for the monitoring of cell membrane receptors on single-cell analysis using SERS in a PDMS-based microfluidic device.

Highlights

The epidemic of obesity in the Western world has been attributed to several factors, including, but not limited to, an increase in sedentary lifestyle, socioeconomic factors, and perhaps most importantly, an overconsumption of nutrients
Because of the poor adhesion ability of HEK293 cell line, the cells were detached under shear flow in the microfluidic environment
The cell proliferation in the deep wells could prevent the detachment of cells during media refreshment and fatty acid injection

Summary

Introduction

The epidemic of obesity in the Western world has been attributed to several factors, including, but not limited to, an increase in sedentary lifestyle, socioeconomic factors, and perhaps most importantly, an overconsumption of nutrients. Of these nutrients, the ingestion of a high fat diet has been implicated as playing a important role leading to the development of dietary-induced obesity [1,2,3]. The best described of these is the long chain polyunsaturated fatty acid receptor, GPR120, which mediates the taste (and post-ingestive) recognition of fat [6].

Methods

Results

Conclusion