A highly sensitive and selective method was developed for both UVevis spectrophotometric and fluorimetric determination of organophosphorus pesticides(OPs). This method used silver nanoparticles(AgNPs) modified with g...A highly sensitive and selective method was developed for both UVevis spectrophotometric and fluorimetric determination of organophosphorus pesticides(OPs). This method used silver nanoparticles(AgNPs) modified with graphitic carbon nitride(g-C_3N_4). The AgNPs reduced the fluorescence intensity of g-C_3N_4. Acetylthiocholine(ATCh) could be catalytically hydrolyzed by acetylcholinesterase(AChE) to form thiocholine, which induces aggregation of the AgNPs. This aggregation led to the recovery of the blue fluorescence of g-C_3N_4, with excitation/emission peaks at 310/460 nm. This fluorescence intensity could be reduced again in the presence of OPs because of the inhibitory effect of OPs on the activity of AChE. The degree of reduction was found to be proportional to the concentration of OPs, and the limit of fluorometric detection was 0.0324 mg/L(S/N=3). In addition, the absorption of the g-C_3N_4/AgNPs at 390 nm decreased because of the aggregation of the AgNPs, but was recovered in presence of OPs because of the inhibition of enzyme activity by OPs. This method was successfully applied to the analysis of parathion-methyl in real samples.展开更多
The booming development of wearable devices has aroused increasing interests in flexible and stretchable devices.With mechanosensory functionality,these devices are highly desirable on account of their wide range of a...The booming development of wearable devices has aroused increasing interests in flexible and stretchable devices.With mechanosensory functionality,these devices are highly desirable on account of their wide range of applications in electronic skin,personal healthcare,human–machine interfaces and beyond.However,they are mostly limited by single electrical signal feedback,restricting their diverse applications in visualized mechanical sensing.Inspired by the mechanochromism of structural color materials,interactively stretchable electronics with optical and electrical dual-signal feedbacks are recently emerged as novel sensory platforms,by combining both of their sensing mechanisms and characteristics.Herein,recent studies on interactively stretchable electronics based on structural color materials are reviewed.Following a brief introduction of their basic components(i.e.,stretchable electronics and mechanochromic structural color materials),two types of interactively stretchable electronics with respect to the nanostructures of mechanochromic materials are outlined,focusing primarily on their design considerations and fabrication strategies.Finally,the main challenges and future perspectives of these emerging devices are discussed.展开更多
Herein,a dual-signal electrochemical biosensor has been developed by self-assembly of pH-activatable i-motif probes on magnetic microparticles(MMPs)coupled with DNA walker for signal amplification.In this study,the cy...Herein,a dual-signal electrochemical biosensor has been developed by self-assembly of pH-activatable i-motif probes on magnetic microparticles(MMPs)coupled with DNA walker for signal amplification.In this study,the cytosine(C)-rich single-stranded DNAs are hybridized with DNA initiators to obtain the long-nicked duplexes with repeated units,which are further captured on MMPs to form the magnetic i-motif containers.The resulting duplexes contain abundant G-C base pairs,thus providing extensive binding sites for doxorubicin(DOX).At acidic pH,the C-rich sequences are folded into i-motif structure,resulting in the release of DOX and walker initiators.In this case,the liberated DOX is adsorbed on gra-phene quantum dots-modified glassy carbon electrode viaπ-πinteraction,while the walker initiators as a moving part can catalyze the hybridization between MB-modified fueler DNA and tracker DNA on electrode,contributing to the generation of dual electrochemical signals induced by MB and DOX.Importantly,the magnetic separation can effectively reduce the background,achieving sensitive biosensing of pH ranging from 4.0 to 7.4 with excellent stability.Moreover,the proposed dual-signal electrochemical biosensor has been successfully applied for accurate monitoring of pH in human serum,which holds great potential in pH-dependent bioassays,especially in ultra-micro analysis for clinical applications.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant No. 21765015, 21808099 to P. Qiu, 31860263 to X. Wang)the Science and Technology Innovation Platform of Jiangxi Province (Grant No. 20192BCD40001), China。
文摘A highly sensitive and selective method was developed for both UVevis spectrophotometric and fluorimetric determination of organophosphorus pesticides(OPs). This method used silver nanoparticles(AgNPs) modified with graphitic carbon nitride(g-C_3N_4). The AgNPs reduced the fluorescence intensity of g-C_3N_4. Acetylthiocholine(ATCh) could be catalytically hydrolyzed by acetylcholinesterase(AChE) to form thiocholine, which induces aggregation of the AgNPs. This aggregation led to the recovery of the blue fluorescence of g-C_3N_4, with excitation/emission peaks at 310/460 nm. This fluorescence intensity could be reduced again in the presence of OPs because of the inhibitory effect of OPs on the activity of AChE. The degree of reduction was found to be proportional to the concentration of OPs, and the limit of fluorometric detection was 0.0324 mg/L(S/N=3). In addition, the absorption of the g-C_3N_4/AgNPs at 390 nm decreased because of the aggregation of the AgNPs, but was recovered in presence of OPs because of the inhibition of enzyme activity by OPs. This method was successfully applied to the analysis of parathion-methyl in real samples.
基金funded by the National Natural Science Foundation of China(No.51873145)the Excellent Youth Foundation of Jiangsu Scientific Committee(No.BK20170065)+1 种基金the Qing Lan Project,the 5th 333 High-level Talents Training Project of Jiangsu Province(No.BRA2018340)the Six Talent Peaks Project in Jiangsu Province(No.XCL-79).
文摘The booming development of wearable devices has aroused increasing interests in flexible and stretchable devices.With mechanosensory functionality,these devices are highly desirable on account of their wide range of applications in electronic skin,personal healthcare,human–machine interfaces and beyond.However,they are mostly limited by single electrical signal feedback,restricting their diverse applications in visualized mechanical sensing.Inspired by the mechanochromism of structural color materials,interactively stretchable electronics with optical and electrical dual-signal feedbacks are recently emerged as novel sensory platforms,by combining both of their sensing mechanisms and characteristics.Herein,recent studies on interactively stretchable electronics based on structural color materials are reviewed.Following a brief introduction of their basic components(i.e.,stretchable electronics and mechanochromic structural color materials),two types of interactively stretchable electronics with respect to the nanostructures of mechanochromic materials are outlined,focusing primarily on their design considerations and fabrication strategies.Finally,the main challenges and future perspectives of these emerging devices are discussed.
基金supported by the National Natural Science Foundation of China(22076087)the Special Funds of the Taishan Scholar Program of Shandong Province(tsqn20161028)+2 种基金the Science Foundation for Distinguished Young Scholars of Shandong Province(ZR2020JQ08)the Youth Innovation Technology Program of Shandong Province(2019KJC029)the Collaborative Innovation Program of Jinan(2018GXRC033).
文摘Herein,a dual-signal electrochemical biosensor has been developed by self-assembly of pH-activatable i-motif probes on magnetic microparticles(MMPs)coupled with DNA walker for signal amplification.In this study,the cytosine(C)-rich single-stranded DNAs are hybridized with DNA initiators to obtain the long-nicked duplexes with repeated units,which are further captured on MMPs to form the magnetic i-motif containers.The resulting duplexes contain abundant G-C base pairs,thus providing extensive binding sites for doxorubicin(DOX).At acidic pH,the C-rich sequences are folded into i-motif structure,resulting in the release of DOX and walker initiators.In this case,the liberated DOX is adsorbed on gra-phene quantum dots-modified glassy carbon electrode viaπ-πinteraction,while the walker initiators as a moving part can catalyze the hybridization between MB-modified fueler DNA and tracker DNA on electrode,contributing to the generation of dual electrochemical signals induced by MB and DOX.Importantly,the magnetic separation can effectively reduce the background,achieving sensitive biosensing of pH ranging from 4.0 to 7.4 with excellent stability.Moreover,the proposed dual-signal electrochemical biosensor has been successfully applied for accurate monitoring of pH in human serum,which holds great potential in pH-dependent bioassays,especially in ultra-micro analysis for clinical applications.
文摘单电感双输出(single-inductor dual-output,SIDO)开关变换器工作在共享充放时序下存在电感电流纹波大、输出支路间交叉影响严重以及电路参数宽范围变化下控制电路不能正常工作等问题.为此,提出一种独立充放时序电流型变频控制(current-mode variable frequency control,C-VF)技术.首先,具体描述变换器在连续导电模式(continuous conduction mode,CCM)下的工作原理,并推导主电路开环传递函数;进一步构建闭环小信号模型,推导闭环交叉阻抗,详细分析不同输出电压及负载电流下变换器的交叉影响特性;最后,通过仿真和实验进行验证.研究表明:相较于共享充放时序,独立充放时序C-VF CCM SIDO buck变换器减小了交叉影响,改善了负载瞬态响应性能;当两支路负载电压不等时,减轻某一支路负载可以降低该支路的交叉影响;当两支路输出电压相同但负载不同时,重载支路对轻载支路的交叉影响更小.
