Fabrication Of Nanozyme And Their Rapid,Sensitive Detection Of Biomolecules

Biomolecules in the human body are often closely related to various metabolism and physiological activities.In contemporary medical research,the content of various biomolecules in the human body is usually detected to monitor human health.However,it is challenging to rapidly and sensitively detect molecules that exist in small amounts and unstable in the complex environment of human body.With the development of nanotechnology,more and more nanomaterials are used as nanomimic enzymes in the construction of biosensors to detect and analyze these small biological molecules.However,in order to realize the highly selective,rapid and sensitive detection of these molecules,it is necessary to reasonably design the nano-mimetic enzymes that they can better meet the needs of practical applications.Based on this,in this paper,different nanozymes were designed by simulating the structure of biological enzymes,regulating the pore structure and active center of nanomaterials,which improved the biocompatibility of nanozymes,and enhance the response speed and sensitivity of nanozymes in detecting small molecules.The main research contents and results are as follows:1.Fe₃O₄@BC nanomimic enzyme for sensitive detection of dopamine in sweatThe catalytic capacity and specificity of simple nanoparticles are far lower than that of natural enzymes.Here,a nanozyme,Fe₃O₄@bacteria cellulose（Fe₃O₄@BC）was designed by mimicking the structure of natural enzymes,in which Fe₃O₄is the redox center,bacterial cellulose plays an important role in protecting Fe₃O₄from aggregation and capturing target sensing molecule.Surprisingly,with the help of BC,our proposed nanozyme not only exhibits wider linear range（0.02～20.5μM）,higher sensitivity(3.69n AμM^-1 cm^-2)and good selectivity towards DA,but displays a lower detection limit（0.594 n M at S/N=3）and good biocompatibility.Further,a flexibility sensor was fabricated by using Fe₃O₄@BC nanozyme as the electrode modifying materials,which can sensitively detect DA in sweat.2.MIL-47（Ⅴ）for rapidely H₂O₂ detection and tumor cell inhibitionIn the first work,Fe₃O₄@BC nanozyme was constructed by simulating the structure of protease,and realized the sensitive detection of DA in sweat.However,for H₂O₂,a kind of unstable molecule,it is more difficult to achieve rapid and in situ monitoring of hydrogen peroxide released from living cells.However,rapid in situ monitoring of hydrogen peroxide（H₂O₂）released from living cells is of great significance for the early diagnosis,case analysis,and treatment of tumors.In this work,a sensitive MIL-47（Ⅴ）-OH monitoring sensor was designed by adjusting the ligand of MIL-47（Ⅴ）to realize the rapid in-situ detection of H₂O₂ released from living cells with high selectivity.The working potential of the as-designed sensor was optimized,and the electrochemical reaction products of H₂O₂ under different working potentials were analyzed by electron paramagnetic resonance（EPR）.Even without an applied voltage,MIL-47（Ⅴ）-OH can convert H₂O₂ into·O₂^-,which validates its ability to inhibit tumor cells.Hence,MIL-47（Ⅴ）-OH is a promising material for H₂O₂ detection,tumor cell inhibition,and thus,application in biological diagnoses and oncology therapy.3.Fe doped Mn-PBA for highly sensitive detection of H₂O₂In the previous work,the detection speed of MIL-47（Ⅴ）for H₂O₂ was improved by regulating the ligand of MOF.In this work,the following attempts were made mainly to address the detection sensitivity of nano-mimetic enzymes.Prussian blue（PB）is a transition metal complex known as"artificial peroxidase".As an analog of PB,Mn-PBA has high peroxidase catalytic activity and also has rich pore structure,large specific surface area,ordered crystal structure similar to MOF,which are beneficial to the detection of H₂O₂.Based on these advantages,Fe³⁺was further doped into Mn-PBA to promote the transformation of Mn^Ⅱ-NC-Fe ^Ⅲ phase to Mn ^Ⅲ-NC-Fe ^Ⅱ phase,and the Mn^Ⅲ-NC-Fe ^Ⅱ structure is more conducive to the electron transfer in the reaction,thus making the nanozyme detect sensitivity for H₂O₂ improved a lot.In addition,the Mn@Fe-PBA material was further etched with thioglycolic acid（TGA）according to the different affinity of Mn^Ⅱ-NC-Fe ^Ⅲ and Mn ^Ⅲ-NC-Fe ^Ⅱ core-shell structures,and the Mn ^Ⅲ-NC-Fe ^Ⅱstructure left after etching,which can achieve higher sensitivity detection of H₂O₂,and finally applied it to in situ sensitive detection of H₂O₂ released by 4T1 cells.To sum up,in this article,we rationally control and modify the nano-mimetic enzymes by simulating the structure of biological enzymes,regulating the ligands of MOF materials,and element doping,etc.,finally realized the rapid and sensitive detection of biological small molecules in biological samples and cells,also provides more references for the purposeful design and construction of nanozymes in the future.