Functional Regulation Of Nano-biosensing Interface And Its Application In Biological Detection

As the key component of a sensor,the nano-biological interfaces influence the sensing property of the sensor such as sensitivity,specificity,recognition efficiency.Conventionally,it is difficult to achieve precise regulation of the sensing substrate.And the sensing probes modified on the sensing substrate tend to lie flat on the surface and intertwine with each other,making the sensing property unsatisfactory.Therefore,it is of vital importance to achieve the precise regulation of the size of sensing substrates and the property of the probe modified on the substrate for building molecular recognition with high-activity.Further,regulating the interaction between acceptor and receptor on cell membrane is benefitial for sensitive detection and regulation of cellular physiological activity.The research work of this thesis is focusing on the regulation of the nanobiological interface including: regulation of the size of the nano-biological sensing substrate,regulation of electron transfer property of DNA,and regulation of the interaction between acceptor and receptor on cell membrane.The main results are as follows:(1)Preparing carbon fiber nanoelectrode(CFNE)with single vesicle resolution is a great challenge in the field of brain science and nervous science.Based on the biophysical property of the intracellular vesicles,we prepared carbon fiber nanoelectrode with high spatial and temporal resolution and the size of CFNE matches well with that of intracellular vesicles..We compared the differences of the release mode and release dynamics of vesicle release events occurred on cell membrane with different release activity.(2)We prepare a gold flower microelectrode(GFME)with nanostructure on the surface of it.The detection sensitivity is regulated by controlling the dimension of GFME.By comparing the response dynamics obtained by GFME of different dimensions,we found that the response dynamics is independent of the dimension of GFME.Further,the nanostructure on the interface of GFME improved the anti-interference property,which can be used for sensitive detection of dopamine from the mixture with ascorbic acid.(3)How to improve the anti-interference of the biosensor in complex system or detection in vivo is the key challenge in the field of biosensing.We develop a bio-electronic device base on the fact that charge can transfer though the double strand DNA.The bioelectronic device shows excellent anti-interference in the aspect of hybridization dynamics and signal stability when used in complex system as well as excellent universality.With the device,we realized the detection and analysis of metabolic kinetics of DNA and small molecule in vivo(4)We developed a biosensing platform based on the binding-induced alteration of DNA conformation which can change the interfacial electron transfer kinetics.The sensing platform shows excellent stability and specificity which is benefitial for the determination of PSA and its aptamer.To investigate the binding sites of aptamer on PSA surface,we classified the epitope bins on PSA surface and sort out the best pairwise to develop sandwich structure for PSA detection.(5)Cell can endocytose nanomaterials such as DNA tetrahedron(TDN),possessing an endocytosis force which is benefit for the internalization of TDN.Aptamer can specifically bind to EpCAM expressed on the cancer cell membrane,possessing an adhesion force for adhesion of TDN-aptamer on the cell membrane.To determine which force dominates under different conditions,we regulated the valence of the TDN-aptamer and analyzed the distribution of TDN-aptamer of different valence by investigating their adhesion on cell membrane and endocytotic internalization in to cell cytoplasm.Finally,we realized the capture of CTC in cancer patient blood with trivalence TDN-aptamer...