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
CONSPECTUS:Implantable biosensors represent a rapidly developing direction with a wide range of applications in biotechnology and life science.For example,the detection of neurotransmitters in the brain has attracted ...CONSPECTUS:Implantable biosensors represent a rapidly developing direction with a wide range of applications in biotechnology and life science.For example,the detection of neurotransmitters in the brain has attracted a lot of attention because of their essential effects for neural activity.The in vivo acute detection of chemicals has been developed for decades,but there are few reports about in vivo chronic monitoring of chemicals probably due to two reasons.First,it is difficult to form stable interfaces between biosensors and tissues.Specifically,most of implantable biosensors are based on stiff electrode materials such as carbon fibers,whose moduli are several orders of magnitude higher than these of soft biological tissues.The mechanical mismatch between them will cause severe inflammatory response during chronic applications.Although some flexible neural probes with mesh geometry consisting of polymer and metal and polymer composite fibers have been employed in chronic electrophysiological recording,they are rarely employed for chronic monitoring of chemicals.Second,electrode deteriorations associated with degradation and fouling of functional materials make chemical recognitions difficult in dynamic environment.Generally,biosensors usually need to be modified with several functional materials including a recognition layer in order to identify specific chemicals from various untargeted chemicals.Although nanomaterials with high surface areas are reported to enhance the loading and immobilization of recognition layers so as to improve the sensitivity of biosensors,nanostructured and soft microelectrodes with high specific surface areas are rarely employed for longterm monitoring of chemicals in vivo.In this Account,we highlight our efforts toward flexible and miniaturized implantable fiber biosensors based on carbon nanotube(CNT)fibers for stable interfaces in vivo.We first summarize the assembly structure of CNT fiber electrodes and their mechanical,electrical,electrochemical,and biocompatible properties.The展开更多
The long-term reliability of the neural electrode is closely related to its implantation behavior.In orderto realize the quantitative research of the implantation behavior in a low-cost and accurate way,a refined brai...The long-term reliability of the neural electrode is closely related to its implantation behavior.In orderto realize the quantitative research of the implantation behavior in a low-cost and accurate way,a refined brainmodel containing meninges is proposed.First,the expected simulation material was selected through measuringthe elastic modulus based on the method of atomic force microscope indentation technique.As a result,the 2%(mass fraction)agarose gel simulated the gray and white matter,the 7:1(volume ratio)polydimethylsiloxane(PDMS)sheet simulated the pia mater,and the polyvinyl chloride(PVC)film simulated the dura mater.Second,based on designing a three-layer structure mold,the brain model was prepared by inverted pouring to realizea flat implantation surface.Finally,the simulation behavior of the brain model was investigated with the ratbrain as a reference.For mechanical behavior of implantation,the implantation force experienced two peaks bothin the brain model and the rat brain,maximum values of which were 10.17 mN and 7.69 mN respectively.Thelarger implantation force in the brain model will increase the strength requirement for the electrode,but reducethe risk of buckling of that in practical application.For humoral dissolution behavior,the dissolution rates ofthe polyethylene glycol(PEG)coating of the electrode in the brain model and rat brain were 7000μm3/s and5600μm3/s,respectively.The faster dissolution rate in the brain model will cause the larger thickness of thecoating design but provide sufficient implantable time in practical application.The establishment of the brainmodel and the research of its simulated behavior are beneficial to the size design of the electrode substrate andcoating,and research of the implantation mechanism,and further increase the functional life of the electrode.展开更多
With Co/GCE in 0.005 mol Tris/L/0.05 mol/L NaCl solution (pH 7.1), a sensitive reductive peak of adriamgcin (ADM) was obtained by the linear scan voltammetry. The peak potential is -0.62 V (vs. SCE). The peak current ...With Co/GCE in 0.005 mol Tris/L/0.05 mol/L NaCl solution (pH 7.1), a sensitive reductive peak of adriamgcin (ADM) was obtained by the linear scan voltammetry. The peak potential is -0.62 V (vs. SCE). The peak current is proportional to the concentration of ADM. The electrochemical behavior of the system was studied by the linear-sweep and cyclic voltammetry. The experiments showed that the reduction at Co/GCE is a quasi-reversible process with adsorption. According to Laviron抯 theory, the electrode reaction rate constant k0 and the electron transfer coefficient a are determined to be 2.15 s-1 and 0.62, respectively. The composition of the surface, valence state of elements and depth distribution of elements on the surfaces of Co/GCE were determined by the X-ray photoelectron spectroscopy and Auger electron spectroscopy. The experiments showed that Co was surely implanted into the surface of GCE. The implanted Co element in the form of Co-C catalyzed the reduction of ADM.展开更多
Objective:To review and assess the ideal length of electrode in cochlear implant patients for hearing preservation. Methods:The English language literature was reviewed for studies including hearing preserva-tion and ...Objective:To review and assess the ideal length of electrode in cochlear implant patients for hearing preservation. Methods:The English language literature was reviewed for studies including hearing preserva-tion and speech understanding for electrodes of different lengths. Results:One prospective trial was found, and there were no studies that randomized patients into different length electrodes with an intent to preserve hearing. Eight studies total included multiple length electrodes and contained data regarding hearing preservation. Conclusions: Although there is some evidence that indicates that shorter electrodes may improve both short and long-term hearing preservation rates in cochlear implant patients, no study has directly compared implant length on hearing preservation in a similar patient pop-ulation. A randomized trial of short and standard length electrodes for hearing preservation is warranted. In the interim, utilization of current electrodes measuring 20e25 mm could seem to be a prudent approach when seeking to preserve residual hearing without unduly compro-mising cochlear coverage.展开更多
测定了Li2 O BaO SiO2 系统的玻璃形成范围和结晶相 ,得到了等水溶性和等膨胀系数曲线。这些图解指出高化学稳定性和低膨胀系数范围仅限于高SiO2 含量区。在Li2 O BaO SiO2 玻璃样品中注入不同剂量钕离子。结果表明 :锂的淬取量在剂量 1...测定了Li2 O BaO SiO2 系统的玻璃形成范围和结晶相 ,得到了等水溶性和等膨胀系数曲线。这些图解指出高化学稳定性和低膨胀系数范围仅限于高SiO2 含量区。在Li2 O BaO SiO2 玻璃样品中注入不同剂量钕离子。结果表明 :锂的淬取量在剂量 1×10 16 ions/cm2 以下明显减少 ,但剂量 15× 10 16 ions/cm2 时减少量变得缓慢。同时用SEM和IRRS进一步分析了侵蚀的玻璃表面。展开更多
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.
基金supported by NSFC(21634003,22075050)MOST(2016YFA0203302)+1 种基金STCSM(20JC1414902)SHMEC(2017-01-07-00-07-E00062).
文摘CONSPECTUS:Implantable biosensors represent a rapidly developing direction with a wide range of applications in biotechnology and life science.For example,the detection of neurotransmitters in the brain has attracted a lot of attention because of their essential effects for neural activity.The in vivo acute detection of chemicals has been developed for decades,but there are few reports about in vivo chronic monitoring of chemicals probably due to two reasons.First,it is difficult to form stable interfaces between biosensors and tissues.Specifically,most of implantable biosensors are based on stiff electrode materials such as carbon fibers,whose moduli are several orders of magnitude higher than these of soft biological tissues.The mechanical mismatch between them will cause severe inflammatory response during chronic applications.Although some flexible neural probes with mesh geometry consisting of polymer and metal and polymer composite fibers have been employed in chronic electrophysiological recording,they are rarely employed for chronic monitoring of chemicals.Second,electrode deteriorations associated with degradation and fouling of functional materials make chemical recognitions difficult in dynamic environment.Generally,biosensors usually need to be modified with several functional materials including a recognition layer in order to identify specific chemicals from various untargeted chemicals.Although nanomaterials with high surface areas are reported to enhance the loading and immobilization of recognition layers so as to improve the sensitivity of biosensors,nanostructured and soft microelectrodes with high specific surface areas are rarely employed for longterm monitoring of chemicals in vivo.In this Account,we highlight our efforts toward flexible and miniaturized implantable fiber biosensors based on carbon nanotube(CNT)fibers for stable interfaces in vivo.We first summarize the assembly structure of CNT fiber electrodes and their mechanical,electrical,electrochemical,and biocompatible properties.The
基金the National Natural Science Foundation of China(No.51675330)。
文摘The long-term reliability of the neural electrode is closely related to its implantation behavior.In orderto realize the quantitative research of the implantation behavior in a low-cost and accurate way,a refined brainmodel containing meninges is proposed.First,the expected simulation material was selected through measuringthe elastic modulus based on the method of atomic force microscope indentation technique.As a result,the 2%(mass fraction)agarose gel simulated the gray and white matter,the 7:1(volume ratio)polydimethylsiloxane(PDMS)sheet simulated the pia mater,and the polyvinyl chloride(PVC)film simulated the dura mater.Second,based on designing a three-layer structure mold,the brain model was prepared by inverted pouring to realizea flat implantation surface.Finally,the simulation behavior of the brain model was investigated with the ratbrain as a reference.For mechanical behavior of implantation,the implantation force experienced two peaks bothin the brain model and the rat brain,maximum values of which were 10.17 mN and 7.69 mN respectively.Thelarger implantation force in the brain model will increase the strength requirement for the electrode,but reducethe risk of buckling of that in practical application.For humoral dissolution behavior,the dissolution rates ofthe polyethylene glycol(PEG)coating of the electrode in the brain model and rat brain were 7000μm3/s and5600μm3/s,respectively.The faster dissolution rate in the brain model will cause the larger thickness of thecoating design but provide sufficient implantable time in practical application.The establishment of the brainmodel and the research of its simulated behavior are beneficial to the size design of the electrode substrate andcoating,and research of the implantation mechanism,and further increase the functional life of the electrode.
基金This work was financially supported by the National Natural Science Foundation of China (Grant No. 29875003) the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 98002709).
文摘With Co/GCE in 0.005 mol Tris/L/0.05 mol/L NaCl solution (pH 7.1), a sensitive reductive peak of adriamgcin (ADM) was obtained by the linear scan voltammetry. The peak potential is -0.62 V (vs. SCE). The peak current is proportional to the concentration of ADM. The electrochemical behavior of the system was studied by the linear-sweep and cyclic voltammetry. The experiments showed that the reduction at Co/GCE is a quasi-reversible process with adsorption. According to Laviron抯 theory, the electrode reaction rate constant k0 and the electron transfer coefficient a are determined to be 2.15 s-1 and 0.62, respectively. The composition of the surface, valence state of elements and depth distribution of elements on the surfaces of Co/GCE were determined by the X-ray photoelectron spectroscopy and Auger electron spectroscopy. The experiments showed that Co was surely implanted into the surface of GCE. The implanted Co element in the form of Co-C catalyzed the reduction of ADM.
文摘Objective:To review and assess the ideal length of electrode in cochlear implant patients for hearing preservation. Methods:The English language literature was reviewed for studies including hearing preserva-tion and speech understanding for electrodes of different lengths. Results:One prospective trial was found, and there were no studies that randomized patients into different length electrodes with an intent to preserve hearing. Eight studies total included multiple length electrodes and contained data regarding hearing preservation. Conclusions: Although there is some evidence that indicates that shorter electrodes may improve both short and long-term hearing preservation rates in cochlear implant patients, no study has directly compared implant length on hearing preservation in a similar patient pop-ulation. A randomized trial of short and standard length electrodes for hearing preservation is warranted. In the interim, utilization of current electrodes measuring 20e25 mm could seem to be a prudent approach when seeking to preserve residual hearing without unduly compro-mising cochlear coverage.
