Study And Application Of Liquid Crystal Sensors Based On Dna Hybridization

The detection of DNA targets has aroused considerable attention due to its wild application in many fields,such as clinical diagnostics,gene expression,agricultural industries,food safety,and environmental monitoring.Currently,the traditional methods,such as fluorescence-based microarray technique and surface plasma resonance(SPR)for detection of DNA have many problems and still need to be improved.Liquid crystals(LCs)are intermediate states of matter with many unique properties,such as sensitive orientation response,elastic strain,and birefringence.A minute physical or chemical change on the surface due to chemical and biological binding events can trigger the orientation response of LCs.Then,the response of LCs can be amplified into the bulk LCs film for macroscopic distances because of their elastic strain and can be further transduced into optical signals,which can be observed with naked eyes through crossed polarizer.Based on the DNA hybridization and the properties of LCs,the liquid crystal-aqueous interface and the liquid crystal-solid interface were built and DNA detection using these two interfaces was studied in this paper.The specific contents are as follows.The building of functional substrate with ssDNA,served as orienting agent,on solid and liquid interface.After the decoration of Triethoxsilylbutyraldehyde(TEA),terminated with aldehyde group,on the solid substrate,ssDNA was immobilized on the surface through the interaction between TEA and amino group of ssDNA.Based on this progress,we studied the influence of time of TEA modification and coverage of ssDNA on functional surface.Exploration of DNA detection on liquid crystal-solid interface.In the principle of above-mentioned method,we built a novel functional substrate to detect DNA.Through optimization of experimental conditions,ssDNA is able to induce 5CB to have a homogeneous orientation,which will be disrupted after addition of complementary DNA.The disorder of 5CB molecules can be observed with polarizing microscope as colorful texture.Under the optimal condition(time of TEA modification is 1h and the ss DNA concentration is 20 nM),this method has splendid specificity,repeatability and has a good limit of detection,which is 0.1 nM.The influence of the different surfactants on the orientation of liquid crystal-aqueous interface.Based on the interaction between surfactants and LCs,we investigated the effects of the different surfactants(trimethylstearylammonium Bromide/dodecyltrimethylammonium Bromide/ trimethyloctylammonium bromide/sodium dodecyl sulfate)on the orientation 5CB on the liquid crystal-aqueous interface.The optimal concentration and time were obtained.What's more,we studied the influence of surfactants with and without same chain length on LC orientation and influence of ssDNA on LC orientation on LC-aqueous interface.These results provide the optimal conditions for the further performance on DNA hybridization.