Production Of The Optical Fiber NanoSensing System And Its Application For Single Cell Detection

The conventional analytical methods which generally choose a mass of cells as the research object could only get an average results of the chosen cells.So,it is often inaccurate or even wrong.But the research based on the nano-fiber optical sensing technology could give the information of a single cell.With the research at a single cell level,more accurate and comprehensive information which indicates the physiological state and the process of the cell could also be obtained.We have built a system which suits single cell analysis.The system mainly involves an inverted fluorescence microscope,a single photon counter and a 100 ps data acquisition card.And we also have written a labview based acquisition procedure for the data acquisition card.Overall debugging indicates that our system is very stable and it can distinguish the fluorescence intensity of a single cell(cell was injected fluorescein).With nano-fiber probes and fluorescence probes,we have measured intracellular pH value of a single yeast cell using the ratio method of the fluorescence intensity.Contrast with the result obtained from multitudinous cells by using the FLS920 combined fluorescence lifetime & steady state spectrometer,we have greatly improved the detection sensitivity(approximately 3.8 times).We have measured the pH values of different single cells under the same environment.The results showed that different single cells have different pH values,even though they are under the same condition.The maximal divergence between them could reach 0.2/pH.So,the average results obtained by the conventional analytical method can't indicate the chemical information differences between the cells.We have studied the effect of the extracellular pH on the intracellular pH value of a single cell.By comparing the effects of external pH_o on pH_i of both natural yeast cell and its heterozygote strains(one with ADH2 gene removed,the other with both ADH2 and its allele removed),a different behavior was observed between these strains,and the natural yeast cells have stronger power to regulate and maintain pH_i as a response to the pH_o changing.This difference will be more outstanding especially when the pH_o is above 9.5.