Functional Nano-materials Devices For Fluid And Cells Detection

Functional nanomaterials have been widely used in the field of new energy, electronics, biomarkers, diagnosis and treatment of diseases, the controllable sustained release of drugs, biological sample separation, food hygiene and safety due to the nanomaterials’ special features and benefits. As a detection sensor device, the organic thin film transistors (OFET) has been widely used in the field of biology, chemistry and physics due to its advantages of high sensitivity, low cost, simple fabrication, flexible and good biocompatible. According to the characteristics of the organic semiconductor materials and detecting samples, the OFET can be divided into the organic field effect transistor and the organic electrochemical transistor, both of which can be used in ions, pH, glucose, DNA, cells, dopamine, stress and optical detection. With the developments of the controllability of materials design and fabrication, the OFET will have more applications in the future.With the development of micro-machining technology, microfluidic chip technology had been used in the capillary electrophoresis for chemical and biological samples separation and detection, especially in the DNA sequence, which can accelerate the research of human genomics sequencing. With the development of soft-lithography as well as the integration of controllable and detection unit in microfluidic chip, the microchip system has been widely used in the sample separation, chemical synthesis, high-throughput drug screening, food hygiene and safety, cell biology and systematics, proteomics and other fields, which means that the microfuidic device becomes the true sense of lab-on-a-chip. Microfluidic chip system has many advantages, such as high-throughput, high sample separation speed, low sample consumption, high detection sensitivity and accuracy, high integration, portability, which make it become interdisciplinary research platform. The size of the microchannel was very close to the size of cells, which makes it suitable for single-cell analysis.This paper has preliminary study the nanomaterials-based detection devices in the applicaiton of food hygiene and safety, early diagnosis of cancer and detection. The devices were also integrated in microfluidic chip for the fluid detection. The shear stress applied on cancer cell induced by the fluid flow in microchannel was used for cell release. The works were described as follows:(1) PEDOT:PSS based organic electrochemical transistor had been fabricated and used for an enterohaemorrhagic bacteria E.coli O157:H7detection. After processed by oxygen plasma treatment and surface chemical modification, the anti-E.coli O157:H7antibody can be grafted on the PEDOT:PSS nanofilm. Then the bacteria can be captured by the device. The effective gate voltage shift was related to the concentration of electrolyte, bacterial surface electric potential and the kind of gate before and after capture bacterial. The detection limitation of the OECT was about100cfu/ml.(2) The PEDOT:PSS based OECT has been integrated in microfluidic chip. Due to the fluid flow, the conductive of the organic film was unstable. We have tested the device response to the velocity of fluid in microchannel. Taking into account the PEDOT:PSS film a thickness of about70nm, which was in the range of electric double layer on the surface of microchannel, we used a thinnest material graphene as the conductive layer in the transistor. The shift of the relative effect gate voltage was related to the concentration of electrolyte, the zeta potential and the direction of fluid flow. The graphene based OFET for velocity detection has a lower detect limitation of1.0mm/s, which shows that the device was high sensitivity as a sensor.(3) In order to increase the capture efficiency of rare cancer cells, we had synthesized TiO2nanoparticles and assembled into the static cell capture substrate. We had studied the effect of the substrate roughness and capture time on the cell capture efficiency. At the optimized capture condition, roughness of85nm and1hour capture time, about the80%and55%of the cancer cell spiked in PBS and artificial human blood can be recovered. This static cancer cell capture technology has been successfully used in the CTCs capture in human peripheral blood sample. On the other hand, this device shows good biocompatibility.(4) We have also integrated the TiO2nanoparticles based cancer cell capture technology in microfluidic chips. With the surface chemical modification, antibody can be grafted on the microchannel surface. Meanwhile, the shear stress induced by the fluid flow has been utilized for cancer cell release. When the shear stress reached400dyn cm-2,90%of the cancer cell can be released. We had also investigated the surface tension for cell release in microchannel, the results show that95%of cells can be released. We believe that this cell capture and release technology has a potential application in the research of CTCs in the future.