Preparation Of Low-Dimensional Black Phosphorus And Its Application In Biological Analysis

Compared with traditional nanomaterials,low-dimensional black phosphorus（including zero-dimensional black phosphorus quantum dots and two-dimensional black phosphorus nanosheets）was a direct bandgap semiconductor,which with a band gap that can be adjusted to the number of layers.The low-dimensional black phosphorus possessed broad optical absorption across UV,infrared and visible light spectrum which could be used as a photosensitizer in photochemical reactions to produce singlet oxygen,and at the same time with a high photothermal conversion efficiency.Low-dimensional black phosphorus materials possessed excellent electrical and electrochemical properties,with good biocompatibility and low cytotoxicity to cells,so it has great potential application in the fields of optical devices,biosensing,energy storage and biomedical.In this paper,we studied the applications in biomedicine and biosensing of the low-dimensional black phosphorus materials.The specific contents are as follows:（1）A composite material H-MnO₂-BPQDs was prepared,the hollow MnO₂ was used as a carrier and black phosphorus quantum dots was constructed as a photosensitizer to achieve combined treatment of tumor cells with PDT,PTT and chemotherapy.Firstly,the manganese dioxide hollow nanostructure（H-MnO₂）with a large specific surface area was synthesized.The cavity was loaded with the antitumor antibiotic doxorubicin.Then the black phosphorus quantum dots was modified on the H-MnO₂ by the reaction of amino and carboxyl groups.The H-MnO₂-BPQDs/DOX could respond to the low pH environment of tumor cells and degrades in a weakly acidic environment to release the tumor therapeutics encapsulated in the cavity.At the same time,it reacts with hydrogen peroxide existing in the tumor microenvironment to produce oxygen,improve the problem of hypoxia in tumor cells,significantly improve the effect of photodynamic therapy,and at the same time,the black phosphorus quantum dots could convert light energy into heat energy.High heat is generated to achieve combined treatment of tumor cells.（2）An electrochemical biosensor was constructed based on two-dimensional black phosphorus nanosheets.Based on the liquid exfoliation method,two-dimensional black phosphorus nanosheets with different thicknesses were prepared by controlling the centrifugal velocity,and characterized by Raman,AFM and TEM.The cationic polymer-polylysine（PLL）was modified on the surface of the black phosphorus nanosheet（BP）by electrostatic interaction to prepare a PLL-BP complex and modified on the electrode.The soybean peroxidase（SBP）was then fixed on the electrode to prepare the electrochemical biosensor based on SBP-PLL-BP.We speculate that the black phosphorene are a promising electron conductor that promotes electron transport.At the same time,the unique pleated layered structure of black phosphorus nanosheets can carry more SBP,providing a good microenvironment for enzyme immobilization and protecting the activity of the SBP.Therefore,the electrochemical biosensor based on SBP-PLL-BP can significantly improve the electrochemical luminescence signal of H₂O₂-Luminol system.It is expected that the electrochemical biosensor based on SBP-PLL-BP can realize the accuracy of trace and low concentration analytes with high sensitive detection.