The Research And Application Of Novel Metal Nanomaterials In Biosensing And Electrocatalysis

With the rapid development of life sciences,accurate analysis of biological enzymes and small molecules related to life processes is of great significance in the field of medical development,clinical diagnosis and environmental monitoring.Nanomaterials exhibit numerous remarkable properties in optical,electrical and magnetic fields deriving from their quantum size effect,surface effect,small size effect and macroscopic quantum tunneling effect.Due to their unique physical and chemical properties,nanomaterials have been widely applied in field of catalysis and bioanalysis.Therefore,based on the prepared novel metal nanomaterials including coinage metal sulfides and rGO/FeP composite,we developed a series of sensing platforms for detection of the diseases-related enzymes and electrocatalytic hydrogen.The main research of this paper is as follows:?1?We report here a facile and sensitive electrochemical method for probing Citrate synthase?CS?activity based on detailed investigations into the nucleic acid-mimicking coordination polymer?CP?formed from the coenzyme A?CoA?-Ag?I?repeat units.Our biosensing approach provides an especial and significant detection mechanism:CS can catalyze the essential condensation reaction between acetyl-coenzyme A?Ac-CoA?and oxaloacetate?OAA?to form citrate and CoA;then,in the presence of Ag?I?,CoA-Ag?I?CP can be in situ formed because of the strong complexation ability of thiol groups of CoA toward Ag?I?.The generated CoA-Ag?I?CP attaches to graphene-modified glassy carbon electrode surface?denoted as CP/GO/GCE?by multiple adenine bases deriving from CoA and acting as the side groups along the polymeric backbone,which displays efficient H₂O₂-electrocatalyzing activity.Under the optimal conditions,CS with a detection limit as low as 1.65 mU/?L could be sensitively probed with a wide linear range from 0.0033 to 0.264 U/?L.Furthermore,with the character of facile detection,high sensitivity and excellent selectivity,this strategy offers a convenient and specific method for CS activity detection and relevant inhibitors screening,which holds a promising potential in the practical application of CS-based biochemical research,disease diagnosis and drug discovery.?2?On the basis of the above finding of metal coordination polymer,we prepared an in-situ formation of metal coordination polymer?TCh-Cu?II?coordination polymer?and developed a novel and ultrasensitive electrochemical assay for the sensing of acetylcholinesterase?AChE?activity and its inhibitor screening.The detection mechanism is on the basis of the concept,that is,AChE could catalyze the hydrolysis of its substrate acetylthiocholine?ATCh?to produce an electroactive thiol-compound thiocholine?TCh?.Subsequently,TCh reacted with Cu?II?to form a positively charged TCh-Cu?II?CP via S-Cu bond.Since the graphene?GO?is a negative compound due to its plenty of carboxyl groups,TCh-Cu?II?CP could absorb onto the graphene-modified glassy carbon electrode?GO/GCE?via electrostatic interaction.What's more,the CP/GO/GCE has the ability to electro-catalyze the O-phenylenediamine?OPD?,generating a high current signal for the sensing of AChE.Using TCh-Cu?II?CP,AChE activity can be analyzed with a dynamic range of 0.05 mU/mL to 100 mU/mL and low detection limit was down to 0.03 mU/mL.The promising application of the proposed method in AChE inhibitor screening was demonstrated.?3?The reduced graphene/Prussian-blue?rGO/PB?composite was synthesized by a simple hydrothermal method.And then after a calcination and low-temperature phosphating process,reduced graphene/iron phosphide?rGO/FeP?composite was obtained and characterized by XRD,TEM and EDX.In addition,we also optimized the mass ratio of reagents graphene?GO?and potassium ferricyanide?K₃[Fe?CN?₆]·3H₂O?.The catalytic performance of hydrogen evolution in 0.5 M H₂SO₄ was characterized by linear sweep voltammetry?LSV?and it shows Tafel slope of 94 mV dec^-1.