Research On The Construction Of Novel Nanomaterials In Biosensing And Drug Screening

Based on the identification of biological molecules and theirdownstream signaling conversion,biosensor has carried out a sequence of analytical methods to detectthe target,to analyze the field of life sciences and chemistry.Compared with other similaranalysis methods,biosensor has many advantages,like the property toimprove the speed of analysis and application flexibility.During recent years,researcherscontinue to make breakthroughs in the field of nanomaterials,the recognition and detection of biomolecules continuous development of newtechnologies for building high sensitivity,high selectivity,fast and efficient novelbiosensor provides perfect design ideas,as biological sensors to achieve differenttarget site rapid testing analysis provides a more powerful platform.Among them,nanomaterials not only possess the advantages of low cost,simple synthesis route and high chemical stability,but also possess good biocompatibility,low cytotoxicity and strong adsorption capacity,which becoming more and more important in the biological signals identification and biological monitoring,and it provides a new prospect for constructing high selectivity,high sensitivity,fast a nd efficient biosensors.Glucosidase is one of the important components of the glycometabolism.α-glucosidase directly involved in the metabolic process of starch and glycogen in the human body,β-glucosidase participate in the metabolism of cellulose and physiological and biochemical pathways.The abnormalities of these enzymes can lead to metabolic diseases.Glucosidase is also drug targets of inhibitors,to regulate the body’s glycometabolism.As an antidiabetic drug,α-glucosidase inhibitors can effectively prevent the deterioration of diabetes by controlling blood glucose levels.And β-glucosidase inhibitors in the virus or bacterial infection,HIV,cancers and other diseases have a good application prospects.Therefore,it is significant for the determination of glucosidase activity and rapid,accurate screening glucosidase inhibitors from the natural or synthetic compounds.However,there still a challenge of high sensitivity and rapid screening for glucosidase inhibitors.Therefore,high sensitivity and high selectivity of glucosidase inhibitor screening method is urgently to be developedin the clinical research and drug development field.Based on the searching of abundant papers,using the nanomaterials and the construction of biosensors,the preparation and application of several novel nanomaterials has been synthesized,and the biosensors has been constructed of for the detection of effective composition,enzymatic activity and the drug screening for glucosidase inhibitors.The main pionts of this thesis are summarized as follow:(1)In the present study,a facile,novel and sensitive fluorescent assay based on nitrogen-doped carbon dots(CDs)through the inner filter effect(IFE)for the detection of α-glucosidase was first developed.The N-doped CDs with green emission were prepared by a one-step hydrothermal synthesis,which were used as the signal output.Through α-glucosidase catalysis,4-nitrophenol was released from 4-nitrophenyl-α-D-glucopyranoside(NGP).Due to its great molar absorptivity,4-nitrophenol was capable of acting as a powerful absorber to affect the fluorescent signal of CDs.By converting the absorption signals into fluorescence signal s,the facile fluorescence assay strategy could be realized for α-glucosidase activity sensing by IFE.The established IFE-based sensing platform offered a low detection limit of 0.01 U/mL(S/N = 3).This proposed sensing approach has also been expanded to the inhibitor screening.As a typical α-glucosidase inhibitor,acarbose was investigated with a detection limit of 10-8 M.Furthermore,the inhibiting ability of the extraction from natural product was also evaluated,and satisfactory results were achieve d.This developed method enjoyed many merits including simplicity,lost cost,high sensitivity,good reproducibility and excellent selectivity.(2)A rapid,facile and ultrasensitive fluorescence sensing system based on nitrogen-doped carbon dots(N-doped CDs)for the detection of ascorbic acid(AA)was developed.The highly photoluminescent N-doped CDs with excellent solubility in water and good biocompatibility were prepared by a one-step hydrothermal synthesis.The addition of AA can intensively suppress the fluorescence of the N-doped CDs through the synergistic effect of the inner filter effect(IFE)and the static quenching effect(SQE).Benefited from the remarkable synergistic effect of IFE and SQE,a facile and ultrasensitive sensor was constructed successfully for AA sensing.The detection procedure was achieved within 2 min.The linear response range of AA was obtained from 10-3 to 10-8 M with a detection limit of 5 nM.This developed method enjoyed many merits including more simplicity,lost cost,high sensitivity,good selectivity,rapid response and excellent biocompatibility.Notably,the proposed fluorescent sensor exhibits excellent performance and applicability for AA determination in human serum and rat brain microdialysate.(3)In this study,a novel and ultrasensitive fluorescence sensing strategy was developed for β-glucosidase activity monitoring using nitrogen-doped carbon dots(N-doped CDs)based on enzyme activated inner filter effect(IFE),where β-glucosidase activities were measured using artificial substrates 4-nitrophenyl-β-D-glycopyranoside(PNPG),the photoluminescent N-doped CDs with green emission were used as signal response.The mechanism of the fluorescence changes of the N-doped CDs was based on the IFE.The detection limit of β-glucosidase was 10-4 U/mL from this study.The widely distributed isoquinoline alkaloids(corynoline,berberine and dehydrocorydaline,etc.)had been extensively investigated due to their potential therapeutic actions and clinical utilities.Here we have chosen corynoline,berberine and dehydrocorydaline for β-glucosidase inhibiting detections for the first trial.Corynoline showed a significant inhibition to β-glucosidase and excellent results were obtained with a detection limit of 0.1 μM.(4)Diabetes is a group of metabolic diseases characterized by high blood sugar,which seriously endangers human health.Recently,Alpha-glucosidase(α-glucosidase)inhibitors as an effective and safe antidiabetic drugs,has receiving more and more attentions.However,the research of find antidiabetic drugs from natural materials is still an issue with great challenge.Herein,we introduced a facile and effective strategy for α-glucosidase inhibitors sensing and screening based on the multi-enzyme complexes with the triangular silver nanoplates as the signal response.The constructed sensor for α-glucosidase inhibitor(acarbose)detection was successfully implemented,and the satisfactory results were obtained with the detection limit of 10 nM.Moreover,the sensing strategy was successfully utilized for trace α-glucosidase inhibitors screening from natural products.