Research On MXenes Quantum Dots And Nanosheets For Biological Detection

Two-dimensional transition metal carbides or nitrides,called MXenes,are a new family of two-dimensional materials.Owing to their excellent physicochemical properties,MXenes can serve as an ideal platform for sensing materials for a variety of applications.In this paper,the MXenes layered material was obtained by exfoliating the MAX phase of aluminum carbide with hydrofluoric acid,and then MXenes quantum dots were obtained by hydrothermal treatment.The application of quantum dots in the detection of histidine and tetracycline was studied.Potential advantages in biomaterial applications.（1）Detection of histidine in serum based on amino-functionalized Ti₃C₂quantum dotsTi₃C₂ MQDs with amino functional groups have been successfully prepared using a one-step hydrothermal method.The obtained functional MQDs possess narrow lateral size distribution,high quantum yield,bright blue photoluminescence,and excellent photostability.MQDs showed high selectivity to Ni²⁺,which suppressed the fluorescence signal of MQDs through internal filtration.In addition,according to the mechanism of Ni²⁺quenching the fluorescence of MQDs and the high affinity between Ni²⁺and histidine,resulting in the dissociation of Ni²⁺from the surface of MQDs and forming a stable compound with histidine,a specific detection of histidine was constructed.The novel turn-on fluorescent nanodetection sensor with a linear range of 0.1–1μM and a detection limit of 2.1 n M.More importantly,we discuss the related experimental process and experimental mechanism,and find that Ni²⁺can quench the fluorescence of MQDs through static quenching;meanwhile,we verify the high affinity between Ni²⁺and histidine.In addition,the recovery rate of histidine in human serum samples was also detected by a standard addition method,proving the reliability and great potential of this detection system in disease diagnosis and bioanalysis.（2）Eu³⁺-doped Ti₃C₂ quantum dots for the detection of tetracycline and its derivativesAmino-functionalized Ti₃C₂ MQDs with blue fluorescence were successfully synthesized and used to construct a ratiometric fluorescence sensing platform for tetracycline detection.The I₆₂₁/I₄₁₀ ratio of the fluorescence intensity of this platform is proportional to the concentration of Tc in aqueous solution,with a detection limit of48.79 n M.Furthermore,this ratiometric fluorescence sensing platform can be used to detect otherβ-diketone ligands of Eu³⁺with satisfactory results.Importantly,when exposed to UV radiation,the color of the fluorescence was also observable to the naked eye from blue to red.Therefore,the mobile phone test strip is used to assist the intelligent application to identify the color system（RGB）of the color change of the Tc test strip.The application of this smart device can not only realize naked eye inspection,but also realize on-site semi-quantitative measurement.（3）Research on antibacterial microneedles based on loaded MXenes nanosheetsTi₃C₂ MXenes nanosheets were obtained by etching the Ti₃Al C₂ material with HF,followed by intercalation to obtain a uniformly dispersed MXenes nanosheet suspension in the solution.MXenes nanosheets have excellent near-infrared absorption ability and extremely high photothermal conversion efficiency.At the same time,the outstanding antibacterial properties of MXenes nanosheets are due to the sharp edges of the MXenes nanosheets themselves cutting the bacterial membrane.The MXenes structure also showed excellent cytocompatibility,maintaining cell viability above 90%at all concentrations tested with a 48h exposure time.Even though the swollen microneedles have mild chronic cytotoxicity,the mixing of MXenes nanosheets with Methyl vinyl ether-maleic anhydride copolymer and polyethylene glycol（PMVE/MA/PEG-10000）microneedles can be used in animal experiments to treat chronic injury in mice.