Study On Electrochemical Sensing Of Marine Heavy Metal Ions And Related Enzymes

The oceans account for about 71%of the total surface of the earth,which are providing a variety of seafood for human beings,meanwhile enrich the human diet.With the continuous development of science and technology and the increasing intensification of human activities,all kinds of wastes will drift to the deep sea eventually,thus causing more and more serious heavy metal pollution.The current situation of heavy metal pollution in rivers and oceans has been paid more and more attention by various countries.Heavy metal pollution in seafood has always been pay attention to.The detection of heavy metal iron in Marine fish and the monitoring of biochemical indicators can measure the degree of heavy metal pollution in fish.The major research contents of ours paper are as follows:1.First of all,members of our group prepared zinc-amalgam film on glassy carbon electrode by in-situ deposition.In situ deposition can reduce or shorten the pretreatment process before analysis.In the fast scan anode stripping voltammetry,the glassy carbon electrode with zinc amalgam film is used as the working electrode,which can quickly and accurately determine the concentration of Zn²⁺.In order to improve the detection limit,we use a printed circuit board(PCB)made by our research group,and an amplifier based on current feedback operation is set on the PCB,which can compensate the resistance drop online.When we are detecting Zn²⁺with in-situ zinc-amalgam film glassy carbon electrode,the Zn²⁺has a good dissolution peak on the mercury film electrode and a high peak current intensity.The scan rate of 500 V/s was chosen for subsequent determination.In this condition,the calibration curve of Zn(II)was obtained.The concentration of Zn(II)and the peak current showed a good linear relationship from 1×10^-7g/m L to 1×10^-11g/m L for Zn(II).The detection limit attained for Zn(II)was estimated up to 3.33×10^-13M(S/N=3).This anodic dissolution voltammetry not only has the characteristics of high sensitivity and selectivity,but also has an affordable price and good research and application value,It can be used for sensitive detection the concentration of zinc ion in the various tissues and organs of Marine fish,and it is convenient to detect the degree of zinc pollution in the sea where those Marine fish live.2.Our research group developed a highly sensitive and selective Pb²⁺detection method based on hybrid chain reaction and deoxynucleotide terminal transferase(Td T)amplification.Four kinds of DNA probes were designed,including a DNA probe containing sulfhydryl group(Pb²⁺-DNAzyme),an auxiliary probe(H0)that can be partially crossed with dna probe and can also initiate HCR reaction,and two hairpin DNA1(H1)and hairpin DNA2(H2)probes that can be involved in HCR amplification reaction.After HCR amplification,the substrate d NTP(d ATP:d GTP=4:6)was introduced,and the 3'-OH terminals of H1 and H2chains were specifically catalyzed by Td T to generate randomly arranged g-rich long strand DNA.Under the action of Pb²⁺,this kind of g-rich DNA strand will change from random curly structure to regular G4 structure.G4 interacts with hemin to form a DNA mimic enzyme with horseradish peroxidase activity and oxidizes 3,3-diaminobenzidine(DAB)to form nonconductive insoluble precipitate(IP).The electron transfer is greatly hindered,resulting in significant amplification of the electrochemical impedance signal.In this paper,the performance of the biosensor was tested by adding lead ion standard solution.The detection limit attained for Pb(II)was estimated up to 0.01 n M(S/N=3).The recovery values for these experiments were between 95.6%and 105.0%?A promising electrochemical method for the detection of heavy metal ions which is related to ocean is presented.3.Herein,we reported a unique G4-nanowires-mediated switch-modulated electrochemical biosensing platform for sensitive nickel ion(Ni²⁺)and histidine(His)detection.The concentration of Ni²⁺and the electrochemical current showed a good linear relationship from 0.5 n M to 500 n M.The detection limit attained for Ni²⁺was estimated up to 0.15n M(S/N=3).The recovery values for these experiments were between 94.7%and 100.7%?The as-proposed electrochemical strategy got the utmost out of the peculiar characteristics including addressable and highly stable DNA-tetrahedron substrate;Terminal deoxynucleotidyl transferase(Td T)-generated stochastic G4-nanowires with unique peroxidase-mimic DNAzyme activity;freewheeling and interesting electrochemical switch modulated by Ni²⁺and His.As expected,the direct effect of Ni²⁺on the peroxidase-mimic DNAzyme activity of the G4-nanowires could be associated with the inhibition and decrease of the signal significantly.Moreover,the emerging His gave rise to a resurgence of electrochemical signal owing to the affinity between Ni²⁺and His.In view of these,the proposed biosensor displayed a suitable detection limit of 0.15 n M for Ni²⁺or 1.2 n M for His,respectively(S/N=3).More importantly,taking on Ni²⁺and His as the model inputs,representative NOT,YES and IMPLICATION logic gates had been accomplished and outputted by readable electrochemical signal change.It is expected to that the unique G4-nanowires-based electrochemical assay hold huge potentials in applications including marine-related environmental monitoring,pharmaceutical analysis and clinical diagnosis.4.We present a novel and simple versatile electrochemical platform for investigating some DNA-related enzymes activity based on Au(III)-coordinated adenine complex(noted as Adenine/Au complex).The synthesized Adenine/Au complex,which possesses good biocompatibility,active electrochemical performance and strong bio-affinity,enables the construction of electrochemical biosensor and further concurrently being exploited for probing DNA-related enzyme activity.The significant strategy is based on three favorable properties:the dazzling polymeric ability of terminal deoxynucleotidyl transferase(Td T);the strong adsorption interaction between Td T-yielded rich T DNA with Adenine/Au complex;the unique electrocatalytic property of Adenine/Au complex.Here,the change in electrochemical response depends on the concentration of Td T or alkaline phosphatase(ALP),so the same novel electrochemical sensor for detecting Td T or ALP can be established with a lower detection limit.Td T concentration and ALP activity were measured by the biosensor,and the lower limits of their detection were 0.01 U/m L(S/N=3)and 0.003 U/L(S/N=3)respectively.Nay,the two developed biosensors display high selectivity,good reproducibility,stability and applicability in inhibitor or real sample investigations.These results prove that the presented Adenine/Au complex gives new insight in multiple-functionally biosensing,further promoting the potential application of Adenine/Au complex-relevant nano-materials in clinical diagnosis.This low cost and flexible electrochemical sensing system with adenine/Au complex provides a simple,rapid and unmarked method for quantitative monitoring of DNA related enzyme activities in marine fish under heavy metal stress.In summary,it is considered that the detection limit of Zn²⁺can be significantly improved by fast scanning anodic dissolution voltammetry based on self-made printed circuit board.Pb²⁺can be detected by using hybrid chain reaction and deoxynucleotide terminal transferase(Td T)amplification.The G4-nanowire mediated switching electrochemical biosensor platform can be used for sensitive detection of nickel ions(Ni²⁺)and histidine(His).Using of adenine/Au complex electrochemical methods produced by DNA polymerization by the Td T DNA related enzyme activity,and the detection result of actual samples proved that these technologies can be used to detect and monitor the concentration of Heavy metal in the fish which was exposed in heavy metal polluted sea waters and the corresponding subtle variations in biochemical indicators for monitoring the Marine pollution of heavy metals.