Multi-modal biochip for simultaneous, real-time measurement of adhesion and electrical activity of neurons in culture

Abstract

Recent evidence suggests that integrin-mediated adhesion of neurons has immediate functional implications for learning and memory. In addition, adhesion of neurons to artificial substrates often determines the effectiveness and life of implants in the brain and peripheral nervous system. In this study, we present a novel biochip capable of simultaneous, quantitative, real-time monitoring of integrin-mediated adhesion and electrophysiology of primary neurons in vitro. The proposed technology combines acoustic micro-resonators capable of tracking changes in mechanics of the adhering neuronal layer, and microelectrode arrays for recording extracellular unit activity. Our results showed in four different experimental paradigms that the acoustic sensor response to adhering cells is correlated to integrin-mediated adhesion and that the micro-sensor is capable of monitoring the dynamics of neuronal adhesion over a period of 9 days. Finally, using our unique dual measurement platform, we performed simultaneous, real-time measurement of integrin-mediated adhesion and single cell electrophysiology in a neuronal culture. The sensitivities of the micro-resonators were 4-5 orders of magnitude greater than the sensitivity of the macro-scale resonators in response to adhering neurons. This multi-functional sensor platform offers insight into the interplay between integrin-mediated adhesion and neural function on a temporal resolution beyond any currently available experimental method and can therefore potentially lead to novel discoveries on the interactions between neuronal adhesion and function.

Design and Development of Microscale Thickness Shear Mode (TSM) Resonators for Sensing Neuronal Adhesion

“…In addition, the presence of high surface roughness leads to slip conditions between the solid and liquid phases as the TSM sensor is operated in liquid, leading to an increase in Δ f . Furthermore, TSM sensors have been shown to be capable of tracking cell adhesion quantitatively in real-time under various chemical and surface treatments (Mindlin and Deresiewicz, 1954; Khraiche et al, 2005; Sapper et al, 2006; Khraiche and Muthuswamy, 2012). In the final section of this work, we investigated TSM sensor response (change in resonant frequency) to cell adhesion on SWCNT modified electrodes over a period of 14 days.…”

“…To remove organic deposits from the surface of the devices, the quartz crystal and gold electrode were cleaned using piranha solution ( H 2 O 2 + H 2 SO 4 ) 3:1 v/v) for 5 min, then rinsed with DI (de-ionized water) water and dried in air for 15 min. The crystal was then treated with 1 M NaOH for 20 min, then rinsed with DI water (Khraiche and Muthuswamy, 2012).…”

“…The stability of AT-cut quartz under temperature change has led to a wide range of applications involving measurement of mass deposition in vacuum. TSM devices can operate in liquid and have been used for a variety of chemical or biosensor applications which include detection and analysis of proteins (serum, neurotransmitters) (Wang and Muthuswamy, 2008), antibodies as well as DNA (Ferreira et al, 2009; Li et al, 2011), self-assembled monolayer (SAMs) (Seker et al, 2016), lipids and cells (neurons, fibroblast, blood cells, neutrophils, bacteria) (Khraiche et al, 2003, 2005; Da-Silva et al, 2012; Khraiche and Muthuswamy, 2012; Zhou et al, 2012; Westas et al, 2015). The first attempts to study adhesion of cells using TSM sensors involved platelet adhesion (Matsuda, 1992).…”

“…Additionally, adding nonadherent beads to the sensor surface showed no change in resonant frequency. These early findings demonstrating the specificity of the changes in resonant frequency of the TSM sensors to cellular adhesion events opened the door to multiple studies using TSM sensors for monitoring adhesion (Khraiche et al, 2005; Khraiche and Muthuswamy, 2012; Lee et al, 2012; Saitakis and Gizeli, 2012; Da-Silva et al, 2013). Although the use of TSM resonators as biosensors encompasses a large number of applications, the commonly used dimensions of the electrodes and resonant frequencies of the crystal in most studies have a narrow range between 5 and 7 mm for electrode diameters, 200 nm for electrode thickness and 5–10 MHz resonant frequencies for the quartz crystal (Kosslinger et al, 1995).…”

Highly Flexible Single-Unit Resolution All Printed Neural Interface on a Bioresorbable Backbone

“…The recorded spikes passing the threshold were then fitted to preloaded templates matching features of neuronal spike activity. Recordings were collected simultaneously from all designed electrodes …”