Continuous Label-Free Electronic Discrimination of T Cells by Activation State

Abstract

The sensitivity and speed with which the immune system reacts to host disruption is unrivaled by any detection method for pathogenic biomarkers or infectious signatures. Engagement of cellular immunity in response to infections or cancer is contingent upon activation and subsequent cytotoxic activity by T cells. Thus, monitoring T cell activation can reliably serve as a metric for disease diagnosis as well as therapeutic prognosis. Rapid and direct quantification of T cell activation states, however, has been hindered by challenges associated with antigen target identification, labeling requirements, and assay duration. Here we present an electronic, label-free method for simultaneous separation and evaluation of T cell activation states. Our device utilizes a microfluidic design integrated with nanolayered electrode structures for dielectrophoresis (DEP)-driven discrimination of activated vs naïve T cells at single-cell resolution and demonstrates rapid (<2 min) separation of T cells at high single-pass efficiency as quantified by an on-chip Coulter counter module. Our device represents a microfluidic tool for electronic assessment of immune activation states and, hence, a portable diagnostic for quantitative evaluation of immunity and disease state. Further, its ability to achieve label-free enrichment of activated immune cells promises clinical utility in cell-based immunotherapies.

Highly Efficient Capture and Quantification of the Airborne Fungal Pathogen Sclerotinia sclerotiorum Employing a Nanoelectrode-Activated Microwell Array

“…Depending on the dielectric properties of the particle and the surrounding medium, the DEP force can be defined as positive or negative, depending on whether the particle is attracted toward the region of maximum electric field gradient or repelled from it. 49 The time-averaged DEP force F DEP acting on a particle of radius r is given by where E is the amplitude of the electric field and ε p * and ε m * are the relative complex permittivities of the particle and medium, respectively, each given by ε* = ε + σ/ j ω, where ω is the frequency of the applied electric field, ε the permittivity, σ is the conductivity of the particle or medium, and j = √(−1). The nonuniform electric field for DEP capture is generated by applying a sinusoidal voltage to the electrodes, which can be configured as an interdigitated electrode (IDE) structure during the process of trapping spores into the microwells ( Figure 1 e).…”

Rapid Screen for Antiviral T‐Cell Immunity with Nanowire Electrochemical Biosensors

“…[35,36] Compatibility with current CMOS technology and microfluidic structures enable low-cost integration of the device into lab-on-a-chip biosensors. [37,38] After fabrication the chips were packaged in a ceramic based dual in-line package (DIP) with a polypropylene cup glued to the surface of the device as a solution chamber with a diameter of ≈5 mm. The exposed wire bonded region is sealed by epoxy to protect it from electrolyte solution (Figure 1c).…”

“…Thus, strategies for rapidly generating donor PBMC-derived APC as a source of autologous pMHC epitopes will be investigated to introduce increased flexibility and generalizability to the assay. However, we suggest that with rapid turnaround times (<15 min), and possibility to be multiplexed with microfluidic methodologies for cell separation and buffer exchange [38,[54][55][56] the nanowire device could be a feasible POC solution for clinical detection and assessment of antigen-specific T-cell immunity.…”

A review: Dielectrophoresis for characterizing and separating similar cell subpopulations based on bioelectric property changes due to disease progression and therapy assessment

“…Dielectrophoresis for immune response monitoring has potential applications in disease diagnostics and prognoses [74]. Dielectrophoretic force measurements using 3D carbon electrodes were used to characterize undifferentiated U937 monocytes and U937 macrophages differentiated from the same lineage [75,76].…”