Conductive Polymer Nanowire Biosensor Fabricated By Nanoscale Soft Lithography

Nowadays,the interface between nanotechnology and biosystems is emerging as one of the broadest and most dynamic areas of science and technology.Nanotechnology,which covers a wide range of disciplines including biology,chemistry,physics and engineering,will revolutionize research in the fields of medicine and life science,for example,the creation of new analysis tools that enable direct,sensitive and rapid analysis of interaction between biological and chemical species,diagnosis disease early and discovery and screening new drug.Among them,biosensors based on one-dimensional nanostructure have become a hot spot in the research of nanosensors due to their unique physical and chemical properties,high surface to body ratio,low power consumption,ultra-high sensitivity and rapid response.Traditional fabricating methods for nanowire devices include"top-down"and"bottom-up"."Bottom-up"method uses nanowires grown by chemical method to prepare functional devices by means of self-assembly."Top-down"methods uses classic nanofabrication techniques(such as photolithography,electron beam exposure,and so on)to fabricate nanostructures directly."Bottom-up"methods has the drawbacks of slow manufacturing and manual labor."Top-down"methods depends on expensive instruments.We report here the use of nanoscale soft lithography technology to fabricate array conductive polymer nanowires biosensor.It involves fabrication of well-defined soft nanogrooves stamp created by nanoscale soft lithography technology.It can be bond to silicon substrate and form a parallel array of nanochannels.Conductive polymer solution is added at both ends of the nano-channel,and it can easily fill the whole channels by capillary force.After the solvent is completely evaporated,it left the nanowire arrays on the silicon substrate.Due to the successful incorporation of PLL-g-OEG₄-Biotin into the nanowires and remaind full functional,the nanowire biosensor can be used to detect streptavidin.When streptavidin binding to the nanowires,the impedance of the nanowire biosensor will change.Further,the binding of streptavidin and biotin can be used to modify nanowire biosensor with specific antibodies of various biomarkers.The device can be widely used in the detection of various biomarkers.Compared with the traditional nanowire device fabricating method,the nanowire fabricating method based on nanoscale soft lithography technology has the advantages of convenient mass production of array,low cost,high repeatability and high biological compatibility.We selected the markers of prostate specific antigen as a protein molecule representative.We modified the anti-PSA/biotin on the device to achieve the device specific detection of prostate specific antigen with extremely low concentration(the detection limit is 10 pg/ml).We selected O157:H7 escherichia coli as the representative of bacteria and modified anti-E.coli/biotin on the device to achieve the qualitative and quantitative detection of O157:H7 escherichia coli at very low concentration(the detection limit was 10 CFU/m L).The experimental results show that the biosensor based on nanoscale soft lithography method can be used to detect biological molecules from nano scale to micron scale.It has great significance and broad application prospect in the field of cancer early detection and food safety.