Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limite...Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limited by various issues,such as low sensitivity,complicated operations,and ethical considerations.In this study,an aptamer-triplex molecular switch(APT-TMS)and gold nanoparticle(AuNP)nanozyme were combined to develop a label-free colorimetric aptasensor for the rapid and highly sensitive de-tection of STX.An anti-STX aptamer designed with pyrimidine arms and a purine chain was fabricated to form an APT-TMS.Specific binding between the aptamer and STX triggered the opening of the switch,which causes the purine chains to adsorb onto the surface of the AuNPs and enhances the peroxidase-like activity of the AuNP nanozyme toward 3,3’,5,5’-tetramethylbenzidine.Under optimized conditions,the proposed aptasensor showed high sensitivity and selectivity for STX,with a limit of detection of 335.6 pmol L^(−1) and a linear range of 0.59-150 nmol L^(−1).Moreover,good recoveries of 82.70%-92.66%for shellfish and 88.97%-106.5%for seawater were obtained.The analysis could be completed within 1 h.The proposed design also offers a robust strategy to achieve detection of other marine toxin targets by altering the corresponding aptamers.展开更多
We investigate an optical compact triplexer based on two photonic crystal waveguides and resonant cavities. For performing wavelength selection, we use three core-shell rods as the resonant cavities. The core rods are...We investigate an optical compact triplexer based on two photonic crystal waveguides and resonant cavities. For performing wavelength selection, we use three core-shell rods as the resonant cavities. The core rods are created by introducing air holes in the center of the silicon rods. By varying the radii of the air holes, three specific wavelengths 1.31, 1.49 and 1.55μm can be obtained. This structure is designed and its performance is verified by the finite-difference time-domain method, which is highly suitable for photonic integrated circuits （PICs）. The average output transmission efficiency and quality factor are more than 98.85% and 560, respectively. The mean value of the crosstalk between output channels is about -36.49 dB. The present device is extremely compact with total size 96.24μm2, which is suitable for PICs and can be utilized in the fiber-to-the-home system.展开更多
CRISPR/Cas9(clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9)系统具有高效、简单、易编辑等特性,在基因工程方面具有巨大潜能。在果蝇(Drosophila melanogaster)基因功能研究中,CRIS...CRISPR/Cas9(clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9)系统具有高效、简单、易编辑等特性,在基因工程方面具有巨大潜能。在果蝇(Drosophila melanogaster)基因功能研究中,CRISPR/Cas9系统也得到了广泛应用。然而利用传统的CRISPR/Cas9系统编辑果蝇基因时,Cas9与sgRNA表达元件往往分别存在于不同果蝇中,需要通过复杂的遗传杂交过程将Cas9与sgRNA整合到一个个体中,操作周期长且较为复杂。本研究在CRISPR/Cas9系统基础上引入tRNA-sgRNA系统和triplex元件,利用triplex元件连接Cas9和tRNA-sgRNA基因,稳定单转录本切割后Cas9 mRNA的末端,实现一个转录本可以同时表达Cas9蛋白和sgRNA,通过一次杂交即可得到相应表型的后代,简化了遗传操作过程。本研究利用这一新的条件性基因编辑系统,分别对果蝇眼部white(w)基因和翅成虫盘broad(br)基因进行条件性敲除,观察到与预期相符的对应表型。因此,该条件性基因编辑系统在高效性、可扩展性和易操作性等方面是对现有CRISPR/Cas9系统进行的重大改进。展开更多
Strand displacement reaction is a crucial component in the assembly of diverse DNA-based nanodevices,with the toehold-mediated strand displacement reaction representing the prevailing strategy.However,the single-stran...Strand displacement reaction is a crucial component in the assembly of diverse DNA-based nanodevices,with the toehold-mediated strand displacement reaction representing the prevailing strategy.However,the single-stranded Watson-Crick sticky region that serves as the trigger for strand displacement can also cause leakage reactions by introducing crosstalk in complex DNA circuits.Here,we proposed the toeless and reversible DNA strand displacement reaction based on the Hoogsteen-bond triplex,which is compatible with most of the existing DNA circuits.We demonstrated that our proposed reaction can occur at pH 5 and can be reversed at pH 9.We also observed an approximately linear relationship between the degree of reaction and pH within the range of pH 5-6,providing the potential for precise regulation of the reaction.Meanwhile,by altering the sequence orientation,we have demonstrated that our proposed reaction can be initiated or regulated through the same toeless mechanism without the requirement for protonation in low pH conditions.Based on the proposed reaction principle,we further constructed a variety of DNA nanodevices,including two types of DNA logic gates that rely on pH 5/pH 9 changes for initiating and reversing:the AND gate and the OR gate.We also successfully constructed a DNA Walker based on our proposed reaction modes,which can move along a given track after the introduction of a programmable DNA sequence and complete a cycle after 4 steps.Our findings suggest that this innovative approach will have broad utility in the development of DNA circuits,molecular sensors,and other complex biological systems.展开更多
DNA circuits are powerful tools in various applications such as logical computation,molecular diagnosis and synthetic biology.Leakage is a major problem in constructing complex DNA circuits.It directly affects the out...DNA circuits are powerful tools in various applications such as logical computation,molecular diagnosis and synthetic biology.Leakage is a major problem in constructing complex DNA circuits.It directly affects the output signal and harms the circuit’s performance significantly.In the traditional DNA circuits,the gate complex is a duplex structure.There are insufficient energy barriers to prevent spontaneous detachment of strands,resulting in a leak prone.Herein,we have developed triplex-structure based DNA circuit with ultra-low leakage and high signal-to-noise ratio(SNR).The triplex structure improves the stability in the absence of input.At the same time,the driving force of the strand displacement cascades reduces the influence of the triplex structure on the desired reaction.The SNR of the DNA circuit was increased to 695,while the desired reaction rate remained 90%of the conventional translator circuit.The triplex-structure mediated leakage prevention strategy was further tested at different temperatures and in DNA translator and seesaw circuits.We also constructed modular basic logic gates with a high efficiency and low leakage.On this basis,we further constructed triplex-structure based tertiary DNA logic circuits,and the SNR reached 295,which,to the best of our knowledge,was among the highest of the field.We believe that our scheme provides a novel,valid,and general tool for reducing leakages,and we anticipate that it will be widely adopted in DNA nanotechnology.展开更多
基金funded by the National Natural Science Foundation of China(No.31801620).
文摘Saxitoxin(STX),one of the most toxic paralytic shellfish poisons discovered to date,is listed as a required item of aquatic product safety inspection worldwide.However,conventional detection methods for STX are limited by various issues,such as low sensitivity,complicated operations,and ethical considerations.In this study,an aptamer-triplex molecular switch(APT-TMS)and gold nanoparticle(AuNP)nanozyme were combined to develop a label-free colorimetric aptasensor for the rapid and highly sensitive de-tection of STX.An anti-STX aptamer designed with pyrimidine arms and a purine chain was fabricated to form an APT-TMS.Specific binding between the aptamer and STX triggered the opening of the switch,which causes the purine chains to adsorb onto the surface of the AuNPs and enhances the peroxidase-like activity of the AuNP nanozyme toward 3,3’,5,5’-tetramethylbenzidine.Under optimized conditions,the proposed aptasensor showed high sensitivity and selectivity for STX,with a limit of detection of 335.6 pmol L^(−1) and a linear range of 0.59-150 nmol L^(−1).Moreover,good recoveries of 82.70%-92.66%for shellfish and 88.97%-106.5%for seawater were obtained.The analysis could be completed within 1 h.The proposed design also offers a robust strategy to achieve detection of other marine toxin targets by altering the corresponding aptamers.
文摘We investigate an optical compact triplexer based on two photonic crystal waveguides and resonant cavities. For performing wavelength selection, we use three core-shell rods as the resonant cavities. The core rods are created by introducing air holes in the center of the silicon rods. By varying the radii of the air holes, three specific wavelengths 1.31, 1.49 and 1.55μm can be obtained. This structure is designed and its performance is verified by the finite-difference time-domain method, which is highly suitable for photonic integrated circuits （PICs）. The average output transmission efficiency and quality factor are more than 98.85% and 560, respectively. The mean value of the crosstalk between output channels is about -36.49 dB. The present device is extremely compact with total size 96.24μm2, which is suitable for PICs and can be utilized in the fiber-to-the-home system.
文摘CRISPR/Cas9(clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9)系统具有高效、简单、易编辑等特性,在基因工程方面具有巨大潜能。在果蝇(Drosophila melanogaster)基因功能研究中,CRISPR/Cas9系统也得到了广泛应用。然而利用传统的CRISPR/Cas9系统编辑果蝇基因时,Cas9与sgRNA表达元件往往分别存在于不同果蝇中,需要通过复杂的遗传杂交过程将Cas9与sgRNA整合到一个个体中,操作周期长且较为复杂。本研究在CRISPR/Cas9系统基础上引入tRNA-sgRNA系统和triplex元件,利用triplex元件连接Cas9和tRNA-sgRNA基因,稳定单转录本切割后Cas9 mRNA的末端,实现一个转录本可以同时表达Cas9蛋白和sgRNA,通过一次杂交即可得到相应表型的后代,简化了遗传操作过程。本研究利用这一新的条件性基因编辑系统,分别对果蝇眼部white(w)基因和翅成虫盘broad(br)基因进行条件性敲除,观察到与预期相符的对应表型。因此,该条件性基因编辑系统在高效性、可扩展性和易操作性等方面是对现有CRISPR/Cas9系统进行的重大改进。
基金financially supported by the National Key Research and Development Program of China(No.2021YFC2701402)the Open Research Fund of State Key Laboratory of Bioelectronics,Southeast University(No.Sklb2021-k06)+1 种基金the Open Foundation of NHC Key Laboratory of Birth Defect for Research and Prevention(Hunan Provincial Maternal and Child Health Care Hospital)(No.KF2020007)the Open Foundation of Translational Medicine National Science and Technology Infrastructure(Shanghai)(No.TMSK-2021-141)。
文摘Strand displacement reaction is a crucial component in the assembly of diverse DNA-based nanodevices,with the toehold-mediated strand displacement reaction representing the prevailing strategy.However,the single-stranded Watson-Crick sticky region that serves as the trigger for strand displacement can also cause leakage reactions by introducing crosstalk in complex DNA circuits.Here,we proposed the toeless and reversible DNA strand displacement reaction based on the Hoogsteen-bond triplex,which is compatible with most of the existing DNA circuits.We demonstrated that our proposed reaction can occur at pH 5 and can be reversed at pH 9.We also observed an approximately linear relationship between the degree of reaction and pH within the range of pH 5-6,providing the potential for precise regulation of the reaction.Meanwhile,by altering the sequence orientation,we have demonstrated that our proposed reaction can be initiated or regulated through the same toeless mechanism without the requirement for protonation in low pH conditions.Based on the proposed reaction principle,we further constructed a variety of DNA nanodevices,including two types of DNA logic gates that rely on pH 5/pH 9 changes for initiating and reversing:the AND gate and the OR gate.We also successfully constructed a DNA Walker based on our proposed reaction modes,which can move along a given track after the introduction of a programmable DNA sequence and complete a cycle after 4 steps.Our findings suggest that this innovative approach will have broad utility in the development of DNA circuits,molecular sensors,and other complex biological systems.
基金the National Natural Science Foundation of China(No.81871732)the National Key Research and Development Program of China(No.2021YFC2701402)+4 种基金the Open Research Fund of State Key Laboratory of Bioelectronics,southeast University(No.Sklb2021-k06)the Open Foundation of NHC Key Laboratory of Birth Defect for Research and Prevention(Hunan Provincial Maternal and Child Health Care Hospital)(No.KF2020007)the Open Foundation of Translational Medicine National Science and Technology Infrastructure(Shanghai)(No.TMSK-2021-141)the Open Fund from Key Laboratory of Cellular Physiology(Shanxi Medical University)Ministry of Education,China(No.CPOF202103).
文摘DNA circuits are powerful tools in various applications such as logical computation,molecular diagnosis and synthetic biology.Leakage is a major problem in constructing complex DNA circuits.It directly affects the output signal and harms the circuit’s performance significantly.In the traditional DNA circuits,the gate complex is a duplex structure.There are insufficient energy barriers to prevent spontaneous detachment of strands,resulting in a leak prone.Herein,we have developed triplex-structure based DNA circuit with ultra-low leakage and high signal-to-noise ratio(SNR).The triplex structure improves the stability in the absence of input.At the same time,the driving force of the strand displacement cascades reduces the influence of the triplex structure on the desired reaction.The SNR of the DNA circuit was increased to 695,while the desired reaction rate remained 90%of the conventional translator circuit.The triplex-structure mediated leakage prevention strategy was further tested at different temperatures and in DNA translator and seesaw circuits.We also constructed modular basic logic gates with a high efficiency and low leakage.On this basis,we further constructed triplex-structure based tertiary DNA logic circuits,and the SNR reached 295,which,to the best of our knowledge,was among the highest of the field.We believe that our scheme provides a novel,valid,and general tool for reducing leakages,and we anticipate that it will be widely adopted in DNA nanotechnology.
