Multi-analyte biosensor interface for real-time monitoring of 3D microtissue spheroids in hanging-drop networks

Abstract

Microfluidics is becoming a technology of growing interest for building microphysiological systems with integrated read-out functionalities. Here we present the integration of enzyme-based multi-analyte biosensors into a multi-tissue culture platform for 'body-on-a-chip' applications. The microfluidic platform is based on the technology of hanging-drop networks, which is designed for the formation, cultivation, and analysis of fluidically interconnected organotypic spherical three-dimensional (3D) microtissues of multiple cell types. The sensor modules were designed as small glass plug-ins featuring four platinum working electrodes, a platinum counter electrode, and an Ag/AgCl reference electrode. They were placed directly into the ceiling substrate from which the hanging drops that host the spheroid cultures are suspended. The electrodes were functionalized with oxidase enzymes to enable continuous monitoring of lactate and glucose through amperometry. The biosensors featured high sensitivities of 322 ± 41 nA mM − 1 mm − 2 for glucose and 443 ± 37 nA mM − 1 mm − 2 for lactate; the corresponding limits of detection were below 10 μM. The proposed technology enabled tissue-size-dependent, real-time detection of lactate secretion from single human colon cancer microtissues cultured in the hanging drops. Furthermore, glucose consumption and lactate secretion were monitored in parallel, and the impact of different culture conditions on the metabolism of cancer microtissues was recorded in real-time.

Multisensor-integrated organs-on-chips platform for automated and continual in situ monitoring of organoid behaviors

“…To this end, the recently emerged organ-on-a-chip systems that combine advanced microfluidic technologies and tissue engineering approaches to simulate both the biology and physiology of human organs have been developed (8,(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). These miniaturized human organ models have several advantages over conventional models, such as more accurate prediction of human responses and, in particular, multiorgan interactions when different organ modules are assembled in a single fluid circuit (7,31).…”

“…For example, prototype microphysiometers have been developed for on-line measurement of glucose and lactate (19,35), oxygen (35), transepithelial electrical resistance (24,36,37), ions (38), extracellular acidification rate (pH), and protein biomarkers (39) in organ-on-a-chip systems (40)(41)(42)(43)(44)(45)(46). However, these sensing units were either built upon a single chip and limited in system-level integration and full automation (19), or were designed for measurements over relatively short periods of time in the range of minutes to hours. In addition, despite that the available commercial sensors are able to monitor a wide range of cellular parameters, such as the Multiparametric BioChip-H (for measuring pH, O 2 , temperature, and electrical signals) by Cellasys, GLU.K.OMETER PRO (for glucose) and LAC PRO (for lactate) by BST, and VisiSens (for 2D visualization of pH, O 2 , or CO 2 distributions) by PreSens, the integration of these sensors with organ-on-a-chip platforms cannot be easily achieved due to their incompatibility with microfluidic systems.…”

Inventions and Innovations in Preclinical Platforms for Cancer Research

“…For the real-time on-chip monitoring of the spheroids, several techniques have been developed including the electrode-based biosensors for oxygen [109], glucose and lactate concentration [110] and also pH and electrical impedance [111] measurements. These monitoring techniques alleviate the need for spheroid retrieval from the chip, which effectively reduces the time and cost.…”

Micro/nanoelectrochemical probe and chip devices for evaluation of three-dimensional cultured cells

“…Several chip devices have been proposed for detection, such as integrated electrode arrays 72 and microfluidics. 73 Misun et al reported a droplet array device with enzyme-modified electrodes for body-on-a-chip applications (Fig. 10).…”

“…10). 73 The microfluidic platform is based on hangingdrop networks for cultivation and analysis of 3D cultured cells. The device monitored both lactate and glucose from single human colon cancer microtissues through amperometry.…”