Label Free Detection of CD4+ and CD8+ T Cells Using the Optofluidic Ring Resonator

John T Gohring,Xudong Fan

doi:10.3390/s100605798

Abstract

We have demonstrated label free detection of CD4+ and CD8+ T-Lymphocyte whole cells and CD4+ T-Lymphocyte cell lysis using the optofluidic ring resonator (OFRR) sensor. The OFRR sensing platform incorporates microfluidics and photonics in a setup that utilizes small sample volume and achieves a fast detection time. In this work, white blood cells were isolated from healthy blood and the concentrations were adjusted to match T-Lymphocyte levels of individuals infected with HIV. Detection was accomplished by immobilizing CD4 and CD8 antibodies on the inner surface of the OFRR. Sensing results show excellent detection of CD4+ and CD8+ T-Lymphocyte cells at medically significant concentrations with a detection time of approximately 30 minutes. This work will lead to a rapid and low-cost sensing device that can provide a CD4 and CD8 count as a measure of HIV progression.

Highlights

The ability to detect and quantify HIV infection is essential to physicians seeking to maximize the impact of treatment and accuracy of prognosis
In this work we have developed an optofluidic ring resonator (OFRR) sensor for label free detection of CD4+ and CD8+ T-Lymphocyte whole cells and CD4+ T-Lymphocyte cell lysis that addresses some of the weaknesses described above
The results show that the OFRR achieves accurate CD4+ and CD8+ counts at levels associated with HIV infection and the medically accepted levels to begin HAART and the AIDS threshold

Summary

Introduction

The ability to detect and quantify HIV infection is essential to physicians seeking to maximize the impact of treatment and accuracy of prognosis. Expanding upon lab-on-a-chip based platforms, devices utilizing metal oxide semiconducting field effect transistors (MOSFETs) to obtain fast CD4+ cell counts and fluorescent technologies to verify cell concentrations have been demonstrated [15] While these methods show promise, the technologies rely heavily on fluorescent tagging and imaging to achieve detection. Having the ring resonator incorporated with a microfluidic channel that is only a hundred micrometers in diameter provides a small device size that uses a very small sample to achieve detection and a short assay time Because of these factors and the label free characteristics of the system, the OFRR could potentially be used in third world countries where resources are limited. The results show that the OFRR achieves accurate CD4+ and CD8+ counts at levels associated with HIV infection and the medically accepted levels to begin HAART and the AIDS threshold

Results and Discussion

CD4 Lysis Measurements

Materials

Experimental Setup

Functionalization of the OFRR Inner Surface

Conclusions