Cell-based Biosensors and Testing Systems for Detecting Cell Growth,Metabolism and Cell Imaging
|Keywords||Cell-based biosensors Electric cell-substrate impedance sensor(ECIS) Light-adressable potiential sensor (LAPS) Electrolyte-insulator-semiconductor (EIS) Single cell imaging Cell growth Cellmetabolism Sensor analyzer|
Cell-based biosensors (CBBs) take live cells and transducers as primary and secondary sensing elements respectively. They can exhibit high-sensitivity, low-cost and high-throughput detection. Thus they have been gradually commercialized and widely applied in the fields of environmental toxicity, food safety and pharmacological screening. Electric cell-substrate impedance sensor (ECIS), a type of cell-based biosensors, is specially to detect the morphology and quantity of adhesive cells such as epithelial cells, fibroblasts, and visceral cells. With outstanding qualities such as non-invasiveness to cells, real-time monitoring, easy to fabricate and high-throughput, it has broad application prospects. Light-adressable potiential sensor (LAPS), also a type of cell-based biosensors, is specially to detect the ion concentration of the solution. It has the potential to detect the ion concentration of extracellular microenvironment of a single cell. Thus, it has been a research hotspot for years. In this dissertation, by combining the studies on ECIS and LAPS, novel cell-based biosensors based on optoelectronic detection principles were designed to meet the trends and needs of cell experiments:multi-parameter detection and single-cell analysis. Moreover, home-made sensor analyzer had been established for testing the cell-based biosensors designed in this paper.The work mainly consisted of four parts as follows:Firstly, detection mechanism of ECIS was systematically explored and the design of ECIS chip was achieved.Based on the electrochemical attributes of metal-electrolyte interface, the electrode impedance model for cells and micro-electrode coupling was systematiclly studied.By discussing the results of detecting cellular impedance using electrodewith different sizes, the optimization criterion for cellular impedance sensing electrodes were summed up. ECIS chip according to the optimization criteria had been successfully applied in preliminary screening of antifibrotic Chinese medicine. Secondly, an optoelectronic cell-based biosensor to simultaneously detect cell growth and metabolism was proposed.The cell impedance and metabolism are two very important parameters of cell physiology. The former reflects the changes in cell morphology and quantity during cell adhesion, proliferation and apoptosis which indicating the growth status of cells; latter reflects the level of energy metabolism in the normal or abnormal cells which indicating the cell activity. By establishing the cell andelectrolyte-insulator-semiconductor (EIS) interface coupling model within this dissertation, the principle of detecting cellular impedance using EIS was explained.Furthermore, according to the different detection principles of EIS and LAPS, special sensor testing system was designed and established to simultaneously detect cellular impedance and cellular metabolism. With the testing system, the toxicity of cadmium on mouse fibroblast cells was successfully tested. The method described here could make up for the shortage of ECIS and LAPS that could only detect one cell physiological parameter; it also simplifies the design of integrated multi-parameter biosensors.Thirdly, a method for single-cell imaging on the chip surface by means of optical addressing was proposed.The feasibility of the method was verified by model analysis. Then, a detailed study of the optoelectronic stability of EIS devices was carried out. Several optimization criterias for improving the stability of EIS device was revealed. The method can compensate the shortages of existing detection techniques (such as ECIS) which could only analyze behavior of cell population so that were lack of distribution information of single cells. Although this method hasn’t yet reach the spatial resolution of an optical microscope, the merits including free of precision optical path, simple operation make it an patiential tool for various cell-based assays, in which single cellresolution is sufficient.Fourthly, a multifunctional and portable automatic sensor analyzer based on the cell-based biosensors was designed and achieved. The overall structure of the sensor analyzer was designed as well as the detection circuits for ECIS, LAPS. The assembly and commissioning of the analyzer were accomplished. The cell experiments of drug screening, drug assessment and cytotoxicity assay were carried out and at last the effectiveness of the instruments were verified.