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...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 10μM.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.展开更多
Growth rate is a widely studied parameter for various cell-based biological studies.Growth rates of cell populations can be monitored in chemostats and micro-chemostats,where nutrients are continuously replenished.Her...Growth rate is a widely studied parameter for various cell-based biological studies.Growth rates of cell populations can be monitored in chemostats and micro-chemostats,where nutrients are continuously replenished.Here,we present an integrated microfluidic platform that enables long-term culturing of non-adherent cells as well as parallel and mutually independent continuous monitoring of(i)growth rates of cells by means of impedance measurements and of(ii)specific other cellular events by means of high-resolution optical or fluorescence microscopy.Yeast colonies were grown in a monolayer under culturing pads,which enabled high-resolution microscopy,as all cells were in the same focal plane.Upon cell growth and division,cells leaving the culturing area passed over a pair of electrodes and were counted through impedance measurements.The impedance data could then be used to directly determine the growth rates of the cells in the culturing area.The integration of multiple culturing chambers with sensing electrodes enabled multiplexed long-term monitoring of growth rates of different yeast strains in parallel.As a demonstration,we modulated the growth rates of engineered yeast strains using calcium.The results indicated that impedance measurements provide a label-free readout method to continuously monitor the changes in the growth rates of the cells without compromising high-resolution optical imaging of single cells.展开更多
基金This work was financially supported by FP7 of the EU through the project‘Body on a chip’,ICT-FET-296257the ERC Advanced Grant‘NeuroCMOS’(contract 267351)as well as by an individual Ambizione Grant 142440 from the Swiss National Science Foundation for Olivier Frey.
文摘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 10μM.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.
基金The work was financially supported by the Swiss SystemsX.ch IPhD program,by the FP7 of the EU through the MTN ISOLATE,Contract Number 289995the Ambizione Grant 142440 of the Swiss National Science Foundation for Olivier Frey.
文摘Growth rate is a widely studied parameter for various cell-based biological studies.Growth rates of cell populations can be monitored in chemostats and micro-chemostats,where nutrients are continuously replenished.Here,we present an integrated microfluidic platform that enables long-term culturing of non-adherent cells as well as parallel and mutually independent continuous monitoring of(i)growth rates of cells by means of impedance measurements and of(ii)specific other cellular events by means of high-resolution optical or fluorescence microscopy.Yeast colonies were grown in a monolayer under culturing pads,which enabled high-resolution microscopy,as all cells were in the same focal plane.Upon cell growth and division,cells leaving the culturing area passed over a pair of electrodes and were counted through impedance measurements.The impedance data could then be used to directly determine the growth rates of the cells in the culturing area.The integration of multiple culturing chambers with sensing electrodes enabled multiplexed long-term monitoring of growth rates of different yeast strains in parallel.As a demonstration,we modulated the growth rates of engineered yeast strains using calcium.The results indicated that impedance measurements provide a label-free readout method to continuously monitor the changes in the growth rates of the cells without compromising high-resolution optical imaging of single cells.
