Study On Electrochemical Analytical Methods Of Glycoconjugates And Derivatives Based On Hydrazone Ligation

As one of the chemoselective linkages,hydrazine chemistry formed by the reaction of a hydrazine group with a free aldehyde group,has the advantages of high selectivity,high linking efficiency,and mild reaction conditions.Considering the structural propertiy saccharides containing aldehyde group,we built three-dimensional gold nanoparticles/ferrocene/liposome nanocluster module based on the specific covalent linkage of hydrazine group with aldehyde groups in saccharide conjugates and their derivatives,and found that the new material MXene has the different binding properties to single stranded DNA and double-stranded DNA,and finally established two new electrochemical biosensors for lipopolysaccharide（LPS）and 5-hydroxymethyl-2-Detection of furfural（HMF）.The main research contents are as follows:1.Constructionofthree-dimensionalgold nanoparticle/ferrocene/liposome nanocluster module and application for lipopolysaccharide analysisIn this part,we first synthesized a three-dimensional gold nanoparticle/ferrocene/liposome nanocluster module mediated by hydrazone chemistry.Specifically,the aldehyde group was first modified on the surface of gold nanoparticles（AuNPs）,and then the liposome containing the electrochemical signal probe ferrocene（Fc）and the recognition group hydrazide was synthesized,and finally a nanocluster module（GFLC）was formed through hydrazone bond formed by the reaction between the aldehyde group on the surface of the AuNPs and the hydrazide group on the surface of the liposome.The formed GFLC owns the functions containing molecular recognition,signal output and signal amplification.Since the surface of GFLC carries a large amount of signal probe Fc and good conductivity of AuNPs,the electrochemical signal intensity for GFLC was 2-4 times higher than that for Fc and ferrocene-containing liposome（FTL）.The results show that GFLC has the good ability for signal output and amplification.We further applied it for the construction of the sensor,and analyzed the lipopolysaccharide.First,pyrene-1-boronic acid（PBA）was modified to the graphite electrode（GE）interface byπ-πstacking.Under acidic conditions,the cis-dihydroxy group of the LPS sugar moiety will form boric acid ester bond with the exposed boric acid group at the electrode interface,resulting in the immobilization of LPS onto the electrode interface.At the same time,LPS oxidized by galactose oxidase can expose a large amount of aldehyde groups,which can form hydrazone chemistry bond with the hydrazide group on the surface of GFLC,leading the immobolizaiton of GFLC onto the electrode interface.Therefore,the analysis of LPS can be achieved by measuring the signal of Fc probe.The results showed that the minimum detection limit of LPS was 0.51×10^-10μg/mL,and current value was linearly correlated concentration of LPS from 2×10^-9μg/mL to 8μg/mL（R²=0.99901）,and the RSD value was 3.4%.In short,the method was simple in operation,wide in detection range,low in detection limit,high in sensitivity and repeatability,and it can be applied to the detection of actual samples and has certain application prospects.2.Study on the interaction beteween novel materials MXene and DNA and application for 5-hydroxymethyl-2-furaldehyde analysisIn this part,we first observed that MXene has different adsorption properties for single stranded DNA and double stranded DNA,that is,MXene can bind to single stranded DNA,but cannot bind to double stranded DNA.Based on this feature,we used MXene to construct a refreshable electrochemical biosensor and tested the sugar derivative HMF through a competitive hydrazone linkage.Specifically,MXene was first modified to the GE interface,and then it was used to adsorb the single stranded DNA（DNA MB-Hyd）containing the electrochemical signal probe methylene blue（MB）and the hydrazide group at each end,to give Hyd-MB/MXene/GE.Then,the HMF analysis was carried out through competitive hydrazine chemistry between HMF and ferrocene formaldehyde（FCA）.Based on the different adsorption characteristics of MXene on single stranded DNA and double stranded DNA,MB-Hyd can be dissociated by complementary single stranded DNA.Thereby,the MXene modified electrode interface can be reused.The results showed that the minimum detection limit of HMF was 9.79×10^-9 mM,and the current value was linearly related to the logarithm vales of concentration in the range of 10 pM to 100mM.The correlation coefficient R² was 0.99746 and the RSD value was 4.56%.At the same time,MXene/GE can be stored in the air for 90 days and can stand up to 24hours of UV exposure.In addition,after repeated usage for 5 times,the detected current value can still reach 93.31%of the original current value,indicating that MXene/GE has good repeatability and application potential..