A compact multifunctional microfluidic platform for exploring cellular dynamics in real-time using electrochemical detection

Abstract

A compact multifunctional microfluidic platform for exploring cellular dynamics in real-time using electrochemical detection Downscaling of microfluidic cell culture and detection devices for electrochemical monitoring has mostly focused on miniaturization of the microfluidic chips which are often designed for specific applications and therefore lack functional flexibility. We present a compact microfluidic cell culture and electrochemical analysis platform with in-built fluid handling and detection, enabling complete cell based assays comprising on-line electrode cleaning, sterilization, surface functionalization, cell seeding, cultivation and electrochemical real-time monitoring of cellular dynamics. To demonstrate the versatility and multifunctionality of the platform, we explored amperometric monitoring of intracellular redox activity in yeast (Saccharomyces cerevisiae) and detection of exocytotically released dopamine from rat pheochromocytoma cells (PC12). Electrochemical impedance spectroscopy was used in both applications for monitoring cell sedimentation and adhesion as well as proliferation in the case of PC12 cells. The influence of flow rate on the signal amplitude in the detection of redox metabolism as well as the effect of mechanical stimulation on dopamine release were demonstrated using the programmable fluid handling capability. The here presented platform is aimed at applications utilizing cell based assays, ranging from e.g. monitoring of drug effects in pharmacological studies, characterization of neural stem cell differentiation, and screening of genetically modified microorganisms to environmental monitoring.

Lab-on-a-disc platform for screening of genetically modified E. coli cells via cell-free electrochemical detection of p-Coumaric acid

“…Although the observed E p was greater than 59 mV, which is the theoretically expected value for a reversible single-electron transfer reaction such that of ferri/ferrocyanide (A.J. Bard, 2001), the values are comparable with those reported for gold electrodes fabricated on glass (Andreasen et al, 2015), plastic (Matteucci et al, 2016) and silicon substrates (Zor et al, 2014). CVs for 8 electrodes on the same disc acquired in 10 mM ferri/ferrocyanide using PBS (pH 7.4) as supporting electrolyte (scan rate 50mVs −1 ).…”

“…Due to the fact that the electrodes were fabricated on the plastic substrate, the optimal electrode cleaning process proposed by Fisher et al (Fischer et al, 2009) proved to be unsuitable due to electrode delamination. However, the electrode surface could be cleaned by linear sweep voltammetry in 50 mM KOH solution in the potential range between -200 and -1200 mV (vs. on disc Au pseudo RE) at the scan rate of 50 mV/s as previously shown by Zor et al (Zor et al, 2014). When CVs recorded for sixteen clean electrodes on two discs were compared with electrodes cleaned after pHCA detection we observed a slight increase in E p (from 98 ± 2 to 111 ± 9 mV) as well as decrease in the oxidation and reduction peak currents (from 421 ± 6 to 398 ± 11 µA and -392 ± 7to -361 ± 16 µA, respectively) .…”

Integrating electrochemical detection with centrifugal microfluidics for real-time and fully automated sample testing

“…This is further supported by comparing the ∆E p found here with ∆E p found in previous studies that used the same electrode design, but had significantly shorter leads in the chip design. 38,41 Then, in the case of shorter thin film leads, the potential peak separations reported is around 90-100 mV. The relatively high peak separation observed here is not problematic as long as the electrodes are behaving reproducibly, and the redox potentials of the compounds subject for detection are not overlapping in this potential window.…”

Label-Free Bioelectrochemical Methods for Evaluation of Anticancer Drug Effects at a Molecular Level

“…Impedimetric assays were performed to investigate the effects of anticancer drugs on different tumor-derived cell lines. Doxorubicin (DOX), an anthracycline-based antibiotic widely used in the treatment of a broad range of solid tumors, as well as acute leukemia and malignant lymphoma, has been used in many reports as a model molecule for studying the effect of dose or time dependency on a specific cell population density [12][13][14], as well as to distinguish cell models of acquired drug resistance [15]. Table 1 summarizes some examples of anticancer drugs that have been evaluated by impedance-based methods.…”