Publication
Current research in the biotechnological field is hampered by the lack of available technologies dedicated to cell monitoring. While on the one hand physicochemical parameters, such as pH, temperature, cell density and adhesion, can be monitored quite easily with automated systems, on the other the variation of cell metabolism is still challenging. Indeed, the real-time detection of metabolites can noticeably extend the knowledge of the molecular biology for therapeutic purposes, as well as for the investigation of several types of diseases. Electrochem- ical biosensors are the ideal candidates for cell monitoring, since they can be integrated with the electronic portion of the system, leading to high-density arrays of biosensors with better performance in terms of signal-to-noise ratio, sensor response, and sample volumes. The present research covers the design, the fabrication, the characterization, and the valida- tion of a minimally-invasive system for the real-time monitoring of different metabolites in a cell culture. The electrochemical biosensor consists of an array of gold working electrodes accomplished by standard microfabrication processes. The deposition of carbon nanotubes and the selective modification with enzymes onto metallic electrodes is performed by adapt- ing an ultra-low volume dispensing system for DNA and protein drop cast. The biological sensing element ensures high selectivity for the target molecule to detect, while nanomate- rials confer superior performance (e.g. sensitivity) with respect to standard immobilization strategies. The on-line detection of glucose, lactate, and glutamate is achieved with an ad hoc fluidic system. The use of a microdialysis probe in direct contact with the cell culture avoids contamination problems and dilution steps for metabolite measurements. Carbon nanotube-based biosensors and the system for real-time measurements are validated on two cell lines under different experimental conditions. The electronic system for electrochemical measurements is also designed and realized with discrete components to be interfaced with the platform. The adopted architecture is able to optimally record the current ranges involved in the electrochemical cell, while the wireless communication between the electronic system and the remote station ensures minimally invasiveness and high portability of the device. Existing technologies and materials are used in an original manner to achieve the on-line monitoring of metabolites in stem cell-like cultures, paving the way for the development of miniaturized, high-sensitive, and inexpensive devices for continuous cell monitoring.