Oriented Assembly Of Copper Based Metal-Organic Frameworks For Electrochemical Sweat Lactate And Glucose Sensing

Human sweat contains rich chemical information.The concentration of sweat lactate and glucose reflects the metabolism of individuals and the health status of individuals can be achieved by real-time monitoring of these two biomarkers.For the current wearable sweat sensor,enzymes-precious metals hybrid materials are efficient as sensing materials for sweat lactate and glucose.But their large-scale and long-term application has been greatly restricted to high price,poor stability and complex fabrication.Accordingly,it is necessary to develop cheap materials as substitutes with excellent performances.Copper-based metal organic frameworks(Cu-MOFs)demonstrate broad application prospect in electrochemical sensors due to great variety,controllable performances,simple preparation and low cost.Therefore,this dissertation focuses on the Cu-MOFs and adoptes a series of methods to realize their oriented assembly for exploring the bifunctional electrochemical non-enzymatic lactate and glucose sensing performances.The main contents are as follows:(1)Using Cu²⁺as metal source and 1,3,5-benzoic acid(H₃btc)as organic ligand,interfacial synthesis and assembly method is adopted to prepare Cu₃(btc)₂ nanocubes and realize the oriented assembly on the surface of amino-functionalized graphene paper.The hybrid materials amino-functionalized graphene paper supported Cu₃(btc)₂nanocubes is obtained.Benefiting from two-dimensional oriented assembly of Cu₃(btc)₂ nanocubes and the improved conductivity provided by graphene substrate,NH₂-GP-Cu₃(btc)₂ exhibits excellent electrocatalytic activity and possesses independent bifunctional electrochemical sensing performances of lactate and glucose.The current responses of NH₂-GP-Cu₃(btc)₂to lactate and glucose are positively correlated with the concentration of sodium and hydroxide ions in the electrolyte,respectively.The detection limits are respective 5?M and 30 n M under alkaline condition.The current responses of NH₂-GP-Cu₃(btc)₂ to lactate and glucose are respective 89.5%and 92.1%of the initial responses after 50 days,which has the capability to realize the non-enzymatic detection of sweat lactate and glucose.(2)Inspired by the rime in nature,Cu(INA)₂ film is assembled on the surface of activated carbon fiber coated with three-dimensional graphene and rimelike ACF-r GO/Cu(INA)₂ is obtained via in-situ electrochemical anode deposition by respectively using Cu²⁺and 4-picolinic acid(HINA)as metal sources and organic ligands.Rimelike ACF-r GO/Cu(INA)₂ contains macropores,mesopores and micropores,effectively promoting the diffusion of ions in analytes and electrolytes as well as electrochemical reactions.Under alkaline condition,lactate and glucose sensitivity of rimelike ACF-r GO/Cu(INA)₂ are 0.047 and 3.1397 m A cm^-2 m M^-1,respectively,demonstrating excellent lactate and glucose sensing performances.It is found that rimelike ACF-r GO/Cu(INA)₂ also possesses sensing performances under acid condition.The sensitivity of lactate and glucose are 46.8 and 16.3?A cm^-2 m M^-1,respectively.Rimelike ACF-r GO/Cu(INA)₂ has the capability to operate in different media and can sensitively detect sweat lactate and glucose without using electrolyte.(3)A strategy of biomimetic natural Murray structure is proposed.Inspired from coffee ring effect,the Cu₂(NDC)₂film is assembled on the modified A4 paper via rapid evaporation driven assembly and epitaxial growth by respectively using Cu(OH)₂and 2,6-naphthalene dicarboxylic acid(H₂NDC)as metal sources and organic ligands.Cu₂(NDC)₂/PDHP with Murray structure is achieved.In Cu₂(NDC)₂/PDHP,the pore size,connection mode and distribution of macropores,mesopores and micropores meet the Murray's law.The number of macropores determines the transportation resistance of the whole Murray structure with the highest transportation efficiency,significantly improving the electrochemical reaction kinetics process.The sensitivity of lactate and glucose of Cu₂(NDC)₂/PDHP are0.0359 and 1.69 m A cm^-2 m M^-1,and the linear range of detection can reach 0.05m M-22.25 m M and 5?m-1.775 m M,respectively.The overall sensing performances are excellent.Sensitivity variation trend of Cu₂(NDC)₂/PDHP with Murray structure in alkaline,neutral and acid media is obtained through analysis of the electrochemical sensing performances affecting factors.The bifunctional detection of sweat lactate and glucose under general conditions is successfully achieved.(4)The fractal MOFs concept is proposed based on natural fractal structure.Inspired by the salt solution evaporation,by respectively using Cu(OH)₂ and2,3,6,7,10,11-hexahydroxytriphenylene(CAT)as metal sources and organic ligands,Cu-CAT fractals are prepared via two-step self-assembly on carbon paper:slow evaporation driven assembly and epitaxial growth.CP/Cu-CAT fractals not only possess electrocatalytic properties of lactate and glucose but also have the detection function of sodium ion.Due to the sub-diffusion and edge effect of fractal structure,under acid condition,the glucose,lactate and sodium ion sensitivity of CP/Cu-CAT fractals are 0.11,1.62 m A cm^-2 m M^-1 and 20 m V/dec,respectively.CP/Cu-CAT fractals with excellent sensing performance can be successfully applied in three function sweat sensing.Sensing behaviors of lactate,glucose and sodium ions are reasonably explained through the observation and summary of electrochemical phenomena.