The chemically modified electrode (CME) which was constructed by covalent attaching erythromycin (ERM) to the glassy carbon (GC) surface was investigated in Tris-HCl buffer (pH=6.0) by cyclic voltammetry (CV) and diff...The chemically modified electrode (CME) which was constructed by covalent attaching erythromycin (ERM) to the glassy carbon (GC) surface was investigated in Tris-HCl buffer (pH=6.0) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In the potential range of -0.5～0.4V, CME yields a pair of stable redox wave. It is the carbonyl group of the ERM molecule immobilized on the GC surface that undergoes two electron redox process involving two protons. The interaction of CME with DNA was also studied by DPV. The CME shows the same interaction with DNA as that in the solution. And the result was proved by fluorescence.展开更多
The electrochemical behavior of pirarubicin(THP) and its interaction with DNA at a Co/GC modified electrode was studied by linear sweep and cyclic voltammetries. In a 0.01 mol/L B-R buffer solution(pH=7.0), the reacti...The electrochemical behavior of pirarubicin(THP) and its interaction with DNA at a Co/GC modified electrode was studied by linear sweep and cyclic voltammetries. In a 0.01 mol/L B-R buffer solution(pH=7.0), the reaction of DNA with THP formed an electrochemical nonactive complex, resulting in a decrease in the THP equilibrium concentration and its reduction current. The composition of the complex was THP∶DNA=2∶1. The combining constant is 2.73×10 10 . The electrode reaction rate constant k s and the electron transfer coefficient α are 1.32 s -1 and 0.56, respectively. The decrease in the peak current was proportional to the DNA concentration and was used to determine the DNA concentration. The experiment of XPS showed that Co was surely implanted into the surface of GCE(glassy carbon electrode) and the implanted Co at GCE can improve the electrocatalytic activity.展开更多
Native calf thymus double stranded DNA (ct-dsDNA) is successfully immobilized from solution onto carbon substrates by covalent linkages under an optimized deposition potential of 1 .8±0.3 V vs. 50 mmol/L NaCl-Ag/...Native calf thymus double stranded DNA (ct-dsDNA) is successfully immobilized from solution onto carbon substrates by covalent linkages under an optimized deposition potential of 1 .8±0.3 V vs. 50 mmol/L NaCl-Ag/AgCl. The long chain DNA fabricates a layer of well conductive nano-netting intertexture, which is stable in pH 14 alkaline solution and in boiling water. The ct-dsDNA modified carbon fiber disk electrode shows two to three orders of magnitude enlarged electrode effective surface area and similarly enlarged voltammetric responses to Co(phen)33+ and dopamine. Thermal dissociated single stranded ct-DNA can also lead to similar result. This modified electrode will find wide applications in the fields of DNA-based electrochemical biosensors.展开更多
The direct detection of clenbuterol（CL） in pig liver without any extraction separation at a pyrrole-DNA modified boron-doped diamond（BDD） electrode is reported. The pyrrole-DNA modified BDD electrode has a strong ...The direct detection of clenbuterol（CL） in pig liver without any extraction separation at a pyrrole-DNA modified boron-doped diamond（BDD） electrode is reported. The pyrrole-DNA modified BDD electrode has a strong electrocatalytic effect on the redox reaction of CL. One oxidization and two reduction peaks of CL appear at 340. 2, 299. 8 and 166. 6 mV（ versus SCE）, respectively. The pyrrole polymer alone cannot electrocatalyze the above reaction at a BDD electrode ; the electrocatalytic effect of a BDD electrode modified with DNA membrane is unsufficient for the analytical detection of CL; the replacement of boron-doped diamond by glass carbon makes the electrocatalytic reaction impossible ; the redox process is pH dependent. The influences of various experimental parameters on the pyrrole-DNA modified BDD electrode were investigated. A sensitive cyclic vohammetric response for CL was obtained in a linear range from 3.4 × 10^-6 to 5 × 10^ -4 mol/L with a detection limit of 8.5 × 10^-7 mol/L. A mean recovery of 102. 7% of CL in the pig liver sample solution and a reproducibility of 3.2% were obtained.展开更多
In the presence of 1-（3-dimethylaminopropyl）-3-ethylcarbodiimide hydrochloride （EDC） and N-hydroxysuccinimide （NHS）, carboxylic group-functionalized single-walled carbon nanotubes （SWNTs） were assembled vertic...In the presence of 1-（3-dimethylaminopropyl）-3-ethylcarbodiimide hydrochloride （EDC） and N-hydroxysuccinimide （NHS）, carboxylic group-functionalized single-walled carbon nanotubes （SWNTs） were assembled vertically on the glassy carbon electrode using ethylenediamine as linking agent to fabricate an aligned electrode （SWNTE）. The morphological characteristic was studied with atomic force microscope （AFM） and its electrochemical property was investigated using K3[Fe（CN）6] as probe. ssDNA had a sensitive voltammetric response at the SWNTE and the oxidative peak potentials of guanine base and adenine base were 0.608 Vand 0.896 V, respectively. Under the optimal conditions, the DPV peak current of guanine base vs. the concentration of ssDNA was linear in the range of 5.4 μg/L-10.8 mg/L with a detection limit of 1 μg/L （S/N = 3）.展开更多
Interactions between deoxyribonucleic acid(DNA) and metal ions are vital for maintaining life functions, however,there are still unsolved questions about its mechanisms. It is of great practical significance to study ...Interactions between deoxyribonucleic acid(DNA) and metal ions are vital for maintaining life functions, however,there are still unsolved questions about its mechanisms. It is of great practical significance to study these issues for medical chip design, drug development, health care, etc. In this investigation, the conductivity properties of λ-DNA solutions with mono-/divalent metal ions(Na+, K^(+), Mg^(2+), and Ca^(2+)) are experimentally studied as they are electrically driven through a 5 μm microfluidic channel. Experimental data indicate that the conductivities of λ-DNA solutions with metal ions(M+/M2+) basically tend to reduce firstly and then increase as the voltage increases, of which the turning points varied with the metal ions. When the voltage surpasses turning points, the conductivity of λ-DNA-M+solutions increases with the concentration of metal ions, while that of λ-DNA-M^(2+)solutions decrease. Moreover, the conductivity of λ-DNA-M^(2+)solutions is always smaller than that of λ-DNA-M+solutions, and with high-concentration M^(2+), it is even smaller than that of the λ-DNA solution. The main reasons for the above findings could be attributed to the polarization of electrodes and different mechanisms of interactions between metal ions and λ-DNA molecules. This investigation is helpful for the precise manipulation of single DNA molecules in micro-/nanofluidic space and the design of new biomedical micro-/nanofluidic sensors.展开更多
Two kinds of DNA-modified electrodes were prepared by covalent and adsorptive immobilization of DNA onto self-assembled monolayers of 2, 2’-dithiodiethanol on gold electrodes and characterized by cyclic voltammetry, ...Two kinds of DNA-modified electrodes were prepared by covalent and adsorptive immobilization of DNA onto self-assembled monolayers of 2, 2’-dithiodiethanol on gold electrodes and characterized by cyclic voltammetry, Xray photoelectron spectroscopy and scanning tunneling microscopy. The results suggest that the methods are satisfactory for the immobilization of DNA on electrodes.展开更多
文摘The chemically modified electrode (CME) which was constructed by covalent attaching erythromycin (ERM) to the glassy carbon (GC) surface was investigated in Tris-HCl buffer (pH=6.0) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In the potential range of -0.5～0.4V, CME yields a pair of stable redox wave. It is the carbonyl group of the ERM molecule immobilized on the GC surface that undergoes two electron redox process involving two protons. The interaction of CME with DNA was also studied by DPV. The CME shows the same interaction with DNA as that in the solution. And the result was proved by fluorescence.
基金the National Natural Science Foundation of China(No.2 0 2 75 0 0 7)
文摘The electrochemical behavior of pirarubicin(THP) and its interaction with DNA at a Co/GC modified electrode was studied by linear sweep and cyclic voltammetries. In a 0.01 mol/L B-R buffer solution(pH=7.0), the reaction of DNA with THP formed an electrochemical nonactive complex, resulting in a decrease in the THP equilibrium concentration and its reduction current. The composition of the complex was THP∶DNA=2∶1. The combining constant is 2.73×10 10 . The electrode reaction rate constant k s and the electron transfer coefficient α are 1.32 s -1 and 0.56, respectively. The decrease in the peak current was proportional to the DNA concentration and was used to determine the DNA concentration. The experiment of XPS showed that Co was surely implanted into the surface of GCE(glassy carbon electrode) and the implanted Co at GCE can improve the electrocatalytic activity.
文摘Native calf thymus double stranded DNA (ct-dsDNA) is successfully immobilized from solution onto carbon substrates by covalent linkages under an optimized deposition potential of 1 .8±0.3 V vs. 50 mmol/L NaCl-Ag/AgCl. The long chain DNA fabricates a layer of well conductive nano-netting intertexture, which is stable in pH 14 alkaline solution and in boiling water. The ct-dsDNA modified carbon fiber disk electrode shows two to three orders of magnitude enlarged electrode effective surface area and similarly enlarged voltammetric responses to Co(phen)33+ and dopamine. Thermal dissociated single stranded ct-DNA can also lead to similar result. This modified electrode will find wide applications in the fields of DNA-based electrochemical biosensors.
基金Supported by the National Natural Science Foundation of China(Nos. 20435010, 20375012, 20205005 and 20475014).
文摘The direct detection of clenbuterol（CL） in pig liver without any extraction separation at a pyrrole-DNA modified boron-doped diamond（BDD） electrode is reported. The pyrrole-DNA modified BDD electrode has a strong electrocatalytic effect on the redox reaction of CL. One oxidization and two reduction peaks of CL appear at 340. 2, 299. 8 and 166. 6 mV（ versus SCE）, respectively. The pyrrole polymer alone cannot electrocatalyze the above reaction at a BDD electrode ; the electrocatalytic effect of a BDD electrode modified with DNA membrane is unsufficient for the analytical detection of CL; the replacement of boron-doped diamond by glass carbon makes the electrocatalytic reaction impossible ; the redox process is pH dependent. The influences of various experimental parameters on the pyrrole-DNA modified BDD electrode were investigated. A sensitive cyclic vohammetric response for CL was obtained in a linear range from 3.4 × 10^-6 to 5 × 10^ -4 mol/L with a detection limit of 8.5 × 10^-7 mol/L. A mean recovery of 102. 7% of CL in the pig liver sample solution and a reproducibility of 3.2% were obtained.
基金supports from the National Science Foundation of China(No.20635020,No.20375020)Doctoral Foundation of the Ministry of Education of China(No.20060426001).
文摘In the presence of 1-（3-dimethylaminopropyl）-3-ethylcarbodiimide hydrochloride （EDC） and N-hydroxysuccinimide （NHS）, carboxylic group-functionalized single-walled carbon nanotubes （SWNTs） were assembled vertically on the glassy carbon electrode using ethylenediamine as linking agent to fabricate an aligned electrode （SWNTE）. The morphological characteristic was studied with atomic force microscope （AFM） and its electrochemical property was investigated using K3[Fe（CN）6] as probe. ssDNA had a sensitive voltammetric response at the SWNTE and the oxidative peak potentials of guanine base and adenine base were 0.608 Vand 0.896 V, respectively. Under the optimal conditions, the DPV peak current of guanine base vs. the concentration of ssDNA was linear in the range of 5.4 μg/L-10.8 mg/L with a detection limit of 1 μg/L （S/N = 3）.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62275216 and 61775181)the Innovation Capability Support Program of Shaanxi Province of China (Grant Nos. S2018-ZC-TD-0061 and TZ0393)the National Key Scientific Instrument and Equipment Development Projects of China (Grant No. 51927804)。
文摘Interactions between deoxyribonucleic acid(DNA) and metal ions are vital for maintaining life functions, however,there are still unsolved questions about its mechanisms. It is of great practical significance to study these issues for medical chip design, drug development, health care, etc. In this investigation, the conductivity properties of λ-DNA solutions with mono-/divalent metal ions(Na+, K^(+), Mg^(2+), and Ca^(2+)) are experimentally studied as they are electrically driven through a 5 μm microfluidic channel. Experimental data indicate that the conductivities of λ-DNA solutions with metal ions(M+/M2+) basically tend to reduce firstly and then increase as the voltage increases, of which the turning points varied with the metal ions. When the voltage surpasses turning points, the conductivity of λ-DNA-M+solutions increases with the concentration of metal ions, while that of λ-DNA-M^(2+)solutions decrease. Moreover, the conductivity of λ-DNA-M^(2+)solutions is always smaller than that of λ-DNA-M+solutions, and with high-concentration M^(2+), it is even smaller than that of the λ-DNA solution. The main reasons for the above findings could be attributed to the polarization of electrodes and different mechanisms of interactions between metal ions and λ-DNA molecules. This investigation is helpful for the precise manipulation of single DNA molecules in micro-/nanofluidic space and the design of new biomedical micro-/nanofluidic sensors.
基金Project supported by the National Natural Science Foundation of China (Grant Nas. 39370213 39770220+2 种基金 29773034)State Key Laboratory for Physical Chemistry of Solid Surfaces (Xiamen University)Natural Science Foundation of Hubei Province (Grant No
文摘Two kinds of DNA-modified electrodes were prepared by covalent and adsorptive immobilization of DNA onto self-assembled monolayers of 2, 2’-dithiodiethanol on gold electrodes and characterized by cyclic voltammetry, Xray photoelectron spectroscopy and scanning tunneling microscopy. The results suggest that the methods are satisfactory for the immobilization of DNA on electrodes.
