The Construction Of Visual Biosensors Based On Carbon-based Nanomaterial

Human beings are facing two major problems: the early diagnosis of cancer and environmental pollution monitoring.And the root of solving this two problems is the grass-roots level.The limitation of the traditional methods cannot be massively applied to the grass-roots level.Therefore,it is of considerable interest to the further research for low-cost,simple,sensitive and portable bimodal biosensor for determination of tumor markers and heavy metal ions.In this paper,we independently designed and manufactured a variety of fluorescence and colorimetric paper-based microfluidic biosensor.A green approach is proposed for in situ growth of precious metal nanomaterials on the paper-based microfluidic devices,which prepared paper-based substrate with low fluorescence background and large surface areas.Around the household type,quick and easy detection diagnosis,combined with the novel nano artificial enzyme visual colorimetric detection.We have successfully proposed fluorescence/colorimetric bimodal biosensors for high sensitive detection of micro RNA small molecules,carcinoembryonic antigen,N-glycan tumor markers and heavy metal ions.Early warning for tumor diseases and environmental pollution detection provides the reliable basis.The main research is as follows:?1?Microfluidic paper-based multiplex colorimetric immunodevice was developed based on the catalytic effect of Pd/Fe₃O₄@C peroxidase mimetics.A non-toxic method was proposed for the simple synthesis of Pd/Fe₃O₄@C.Compared with the natural enzyme,Pd/Fe₃O₄@C possessed many advantages such as good stability and good biological compatibility.The design of multi-channel 3D paper chips and further signal amplification through the growth of gold nanoflowers in the paper substrate,which was applied to detect various antigen antibody at the same time.This nano artificial enzyme could be widely used in biotechnology and medicine area.?2?Paper analytical devices for dynamic evaluation of cell surface N-glycan expression via a bimodal biosensor based on graphene quantum dots.Firstly,a dense interconnected gold nanorods layer was grown on the surfaces of cellulosefibers,which could effectively reduce the paper background fluorescence signal.Then,regrowth a porous silver layer and multibranched hybridization chain reaction for double signal amplifier,further improve the detection sensitivity.Based on the above principle,this strategy was successfully proposed a high sensitivity,low cost,fast and visual multi-channel biosensor,which applied to dynamically monitor cel-surface N-glycan expression.?3?Metal-enhanced ratiometric fluorescence/naked eye bimodal biosensor was used for determination of trace Pb2+ based on doped carbon dots.The detection of the proposed biosensor included preliminary visual inspection of the color change and accurate ratiometric fluorescence analysis.The introduction of ZnFe2O4@Au-Ag bifunctional nanocomposite not only made this biosensor regenerate because of its magnetism but also enhanced fluorescence intensity.Sulfur nitrogen doped carbon dots had a higher fluorescence yield.The proposed biosensor could be used for Pb2+ in environmental monitoring.?4?Metal-enhanced fluorescence/visual bimodal platform was proposed for multiplexed ultrasensitive detection of Micro RNA based on doped carbon dots and reusable paper analytical devices.A flower-like silver layer was grown on the surfaces of cellulosefibers,which could not only effectively reduce the paper background fluorescence but also enhanced fluorescence intensity of nitrogen doped carbon dot.The fluorescent paper could be reused by the supplementation of fluorescent probe.The design of multi-channel paper base sensor achieved a variety of Micro RNA detection at the same time.This novel biosensor could be extended to other proteins or new biomarkers for disease diagnosis and fundamental research.