Design And Preparation Of Noble Metal Nanoprobes And Detection Of Biological Small Molecules

Biological small molecules,as fundamental substances in the composition of the human body,are widely involved in biological physiological functions,metabolic diseases,drug and toxicological studies.The metabolic levels of biomolecules in the human body can accurately reflect the health status of a person,and certain biomolecules,such as dopamine,hyaluronidase,and histidine,have been shown to have a direct relationship with diseases in the human body.Detection of the levels of these small biological molecules in human tissues enables early diagnosis of diseases and is an important way to prevent and treat major diseases.Studies have shown that early diagnosis of many major diseases such as tumors,Parkinson's disease,and depression is important for the treatment and prognostic outcome of cancer.The present means of early diagnostic screening,although mature,suffer from the problems of complicated operation,low sensitivity and expensive instruments.Early diagnostic methods based on detecting the level of biomolecules in the human body as a judgment are an important aspect of life science research.In this study,we designed and prepared noble metal nanomaterials as detection probes,and designed nanoprobes for highly sensitive and selective detection of biological small molecules by studying the structural characteristics of biomolecules and performing surface modification,and prepared nano-detection devices with easy portability,stable performance and convenient operation based on smartphone software.The main research contents are as follows.1.Facile and accuracy detecting dopamine(DA)in biological samples is crucial for diagnostic needs.This study reports a portable colorimetric fluorescent probe for the tracing of DA based on orange-red emitted Au nanoclusters(AuNCs).The AuNCs were reduced and stabilized with L-methionine by controlling the reaction conditions strictly.The resultant L-methionine capped AuNCs(M-AuNCs)exhibit bright and stable orange-red emission with excitation/emission wavelength at 420 nm/610 nm.The bright orange-red emission and large Stoke shift of 190 nm endow M-AuNCs great potential as late-model sensing probe for life studies and environmental science.The M-AuNCs exhibit unique specificity for tracing DA by“on-off”strategy within other biological small molecules.The resulted limit of lower detection(LOD)3.96 n M(S/N=3)within a linear range of 10-100 n M for DA detection was found in this work.Notably,the colorimetric detection results can be explored as visual sensor for sensitive,reliable and real-time/on-site detection of DA by assistant of smartphone supported by color recognizer App.The LOD can be determined at 81.94 n M within a wide linear range of 0.1-1.0?M by smartphone.Furthermore,the as a late-model potable probe M-AuNCs allows simple and rapid discriminating of DA in serum,with results demonstrating its great feasibility for the tracing of DA in real samples.2.Hyaluronidase(HAase)can be regarded as a diagnostic and prognostic urinary biomarker for bladder cancer and brain.In this work,a highly sensitive and selective colorimetric strategy for hyaluronidase(HAase)assay was developed by synthesis of hyaluronic acid(HA)capped Ag nanoparticles(HA-AgNPs).The detection was based on the specific enzymatic digestion between HA and HAase,with the characteristic evolution of localized surface plasmon reason of AgNPs.The capped HA-AgNPs were took on reddish color with diameter of about 20 nm,the introduction of HAase cause the cleavage of HA into small frag merits,the HA-AgNPs were also smashed to smaller nanoparticles with diameter of around 5 nm accompanied fragmentary HA,lead to the color evdution of AgNPs.The quick-witted colorimetric response assured the determination of HAase with limit of 7.24×10^-4 U/m L within scale of 0.01-0.08 U/m L.Notably,the proposed method exhibits good recovery in the human serum and urine,indicate the reliability of HA-AgNPs.3.Gold and silver nanoclusters(AuAgNCs)were synthesized and electrospun with poly(cellulose acetate)and AuAgNCs as precursors to prepare micro-hollow hemisphere shaped electrospun nanofiber membranes(ENM)by electrostatic spinning method to obtain ratiometric fluorescent nanodevices AuAg-ENM for sensitive,rapid and visual detection of Cu²⁺and Hg²⁺as well as histidine(His),and can be the structure of AuAg-ENM is composed of a unique homogeneous micro-hollow hemispherical structure formed by electrospinning technique,which has a larger specific surface area than fibrous filaments and is more conducive to improve the detection sensitivity of nanoparticles.The bimetallic AuAgNCs sensing probes exhibit fluorescence quenching with Hg²⁺and Cu²⁺,and after quenching the detection device can recover the fluorescence of the Cu²⁺detection device by the action of His,which not only achieves the distinction between Hg²⁺and Cu²⁺but also achieves a linear correlation between the concentration of His and the recovery of the fluorescence intensity of the device.This allows AuAg-ENM to have similar functional performance in monitoring Hg²⁺and Cu²⁺with a wide range of fluorescence colors from red to purple to blue.Sensitive,reliable and real-time/in situ detection of Hg²⁺and Cu²⁺is accomplished through a smartphone app.Evaluate the utility and feasibility of the AuAg-ENM sensing system in complex environmental water samples,including seawater,river water and lake water.The detection of His can be effectively accomplished,and the stability and reliability of the AuAg-ENM sensing system in human serum were explored to demonstrate the accuracy of the AuAg-ENM sensing system in detecting His.A Boolean logic gate system was prepared using Hg²⁺,Cu²⁺and His as three chemical inputs.This AuAg-ENM ratiometric detection system is expected to be a promising portable,rapid and accurate sensor for multiplex monitoring of probes,which may provide a basis for highly sensitive detection of biological small molecules in real environment and human.4.The design makes use of the immune response mechanism between antibody and antigen to design a"solid-phase antibody-antigen-labelled immunoassay device"using gold nanoparticles as seeds,assembling 4-ATP on its surface and functionalising antibodies on its surface to detect very small amounts of cotinine by silver staining.The latent fingerprint can be visualised within 3 min,allowing rapid determination of the presence of cotinine components and achieving the goal of rapid detection of cotinine.The assembly of the SERS marker 4-ATP improves the sensitivity of the instrument,and the SERS signal gradually decreases with the concentration of TNT in the range of 10^-4-10^-9 M.The effective detection concentration LOD=10^-7 M.This confirms the high sensitivity and selectivity of the antibody-antigen reaction,and provides a good basis for the rapid and efficient detection of cotinine in the immune response to antibody and antigen.This provides a reliable basis for the rapid and efficient detection of SERS based on antibody and antigen immune response.