Multicolor Cell Imaging With Functional Fluorescent DNA Probes

With the rapid development of bioanalytical chemistry,there is an increasing requirement of multicomponent simultaneous analysis inside cells.Multicolor cell imaging methods have been paid more and more attention due to its excellent properties,such as intuitive,visual,and multicomponent ananlysis.Developing new multicolor imaging probes and imaging strategies is of great significance to study the biological issues,such as intracellular interaction and cell communication,and achieve more accurate diagnosis of diseases.Due to its excellent recognition ability,good biocompatibility and easy to be multifunctionized,functional DNA probes have unique advantages in multicolor imaging applications.In our present work,we have realized single cell typing and multicolor imaging inside living cells through designing new multicolor nanoprobes and developing new multicolor imaging strategies.The main contents of the present dissertation are as follows:1.We found that the cell imaging results of dye labeled aptamers in the complete medium is not only affected by the sequence,but also by the types of dyes and even the substituent of dyes.By making full use of the interaction between cells and aptamers,the partial degradation of dye-labeled aptamers and the different interaction between the degradation products and cells,we developed a new multicolor imaging strategy with three dye-labeled aptamers simultaneously.Taking the intensity of three dyes inside individual cells as classification basis,we could not only distinguish the cancerous cells quickly from large quantities of noncancerous cells,but also identify the type of the cancerous cells at single cell level.This work provides a new choice for the early identification of cancer cells.2.We constructed a new multicolor probe with a DNA tetrahedron based on the competitive chain replacement reaction.This probe is simple synthesis,highly specific,fast responding,and has good enzyme resistance and transmembrane ability.With this multicolor probe,we have realized simultaneous detection of three mRNAs inside cells and visualized the different expression level between the MCF-7cells and MCF-10 A cells.Furthermore,we also studied the different expression level of MCF-7 cells after different drug stimulation.We believe this multicolor probe will have potential application for cancer dignostic in the future.3.We constructed a ratiometric multicolor probe with a DNA tetrahedron based on the damage effect of hydroxyl radicals on single strand DNA.This probe has theadvantages of simple synthesis,ratiometric detection,and subcellular localization.We could realize the ratiometric detection of hydroxyl radicals and semi quantitative detection of pH simultaneously.We visualized the pH and hydroxyl radicals inside the lysosome through multicolor imaging with this ratiometric probe.This part of work has provided a new method for in situ study the interaction of different substances inside cells.