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Matt Aldissi - One of the best experts on this subject based on the ideXlab platform.

  • challenges of electrochemical impedance spectroscopy in protein biosensing
    Analytical Chemistry, 2009
    Co-Authors: Anastasia Bogomolova, Elena Komarova, K Reber, T Gerasimov, Ozlem Yavuz, S Bhatt, Matt Aldissi
    Abstract:

    Electrochemical impedance spectroscopy (EIS) measurement, performed in the presence of a Redox Agent, is a convenient method to measure molecular interactions of electrochemically inactive compounds taking place on the electrode surface. High sensitivity of the method, being highly advantageous, can be also associated with nonspecific impedance changes that could be easily mistaken for specific interactions. Therefore, it is necessary to be aware of all possible causes and perform parallel control experiments to rule them out. We present the results obtained during the early stages of aptamer-based sensor development, utilizing a model system of human alpha thrombin interacting with a thiolated DNA aptamer, immobilized on gold electrodes. EIS measurements took place in the presence of iron ferrocyanides. In addition to known method limitations, that is, inability to discriminate between specific and nonspecific binding (both causing impedance increase), we have found other factors leading to nonspecific i...

  • challenges of electrochemical impedance spectroscopy in protein biosensing
    Analytical Chemistry, 2009
    Co-Authors: Anastasia Bogomolova, Elena Komarova, K Reber, T Gerasimov, Ozlem Yavuz, S Bhatt, Matt Aldissi
    Abstract:

    Electrochemical impedance spectroscopy (EIS) measurement, performed in the presence of a Redox Agent, is a convenient method to measure molecular interactions of electrochemically inactive compounds taking place on the electrode surface. High sensitivity of the method, being highly advantageous, can be also associated with nonspecific impedance changes that could be easily mistaken for specific interactions. Therefore, it is necessary to be aware of all possible causes and perform parallel control experiments to rule them out. We present the results obtained during the early stages of aptamer-based sensor development, utilizing a model system of human alpha thrombin interacting with a thiolated DNA aptamer, immobilized on gold electrodes. EIS measurements took place in the presence of iron ferrocyanides. In addition to known method limitations, that is, inability to discriminate between specific and nonspecific binding (both causing impedance increase), we have found other factors leading to nonspecific impedance changes, such as: (i) initial electrode contamination; (ii) repetitive measurements; (iii) additional cyclic voltammetry (CV) or differential pulse voltammetry (DPV) measurements; and (iv) additional incubations in the buffer between measurements, which have never been discussed before. We suggest ways to overcome the method limitations.

Anastasia Bogomolova - One of the best experts on this subject based on the ideXlab platform.

  • challenges of electrochemical impedance spectroscopy in protein biosensing
    Analytical Chemistry, 2009
    Co-Authors: Anastasia Bogomolova, Elena Komarova, K Reber, T Gerasimov, Ozlem Yavuz, S Bhatt, Matt Aldissi
    Abstract:

    Electrochemical impedance spectroscopy (EIS) measurement, performed in the presence of a Redox Agent, is a convenient method to measure molecular interactions of electrochemically inactive compounds taking place on the electrode surface. High sensitivity of the method, being highly advantageous, can be also associated with nonspecific impedance changes that could be easily mistaken for specific interactions. Therefore, it is necessary to be aware of all possible causes and perform parallel control experiments to rule them out. We present the results obtained during the early stages of aptamer-based sensor development, utilizing a model system of human alpha thrombin interacting with a thiolated DNA aptamer, immobilized on gold electrodes. EIS measurements took place in the presence of iron ferrocyanides. In addition to known method limitations, that is, inability to discriminate between specific and nonspecific binding (both causing impedance increase), we have found other factors leading to nonspecific i...

  • challenges of electrochemical impedance spectroscopy in protein biosensing
    Analytical Chemistry, 2009
    Co-Authors: Anastasia Bogomolova, Elena Komarova, K Reber, T Gerasimov, Ozlem Yavuz, S Bhatt, Matt Aldissi
    Abstract:

    Electrochemical impedance spectroscopy (EIS) measurement, performed in the presence of a Redox Agent, is a convenient method to measure molecular interactions of electrochemically inactive compounds taking place on the electrode surface. High sensitivity of the method, being highly advantageous, can be also associated with nonspecific impedance changes that could be easily mistaken for specific interactions. Therefore, it is necessary to be aware of all possible causes and perform parallel control experiments to rule them out. We present the results obtained during the early stages of aptamer-based sensor development, utilizing a model system of human alpha thrombin interacting with a thiolated DNA aptamer, immobilized on gold electrodes. EIS measurements took place in the presence of iron ferrocyanides. In addition to known method limitations, that is, inability to discriminate between specific and nonspecific binding (both causing impedance increase), we have found other factors leading to nonspecific impedance changes, such as: (i) initial electrode contamination; (ii) repetitive measurements; (iii) additional cyclic voltammetry (CV) or differential pulse voltammetry (DPV) measurements; and (iv) additional incubations in the buffer between measurements, which have never been discussed before. We suggest ways to overcome the method limitations.

Alberto A Iglesias - One of the best experts on this subject based on the ideXlab platform.

  • on the functionality of the n terminal domain in xylanase 10a from ruminococcus albus 8
    Enzyme and Microbial Technology, 2020
    Co-Authors: Alem Storani, Sergio Adrian Guerrero, Alberto A Iglesias
    Abstract:

    We analyzed the structure to function relationships in Ruminococcus albus 8 xylanase 10A (RalXyn10A) finding that the N-terminus 34-amino acids sequence (N34) in the protein is particularly functional. We performed the recombinant wild type enzyme's characterization and that of the truncated mutant lacking the N34 extreme (RalΔN34Xyn10A). The truncated enzyme exhibited about half of the activity and reduced affinity for binding to insoluble saccharides. These suggest a (CBM)-like function for the N34 motif. Besides, RalXyn10A activity was diminished by Redox Agent dithiothreitol, a characteristic absent in RalΔN34Xyn10A. The N34 sequence exhibited a significant similarity with protein components of the ABC transporter of the bacterial membrane, and this motif is present in other proteins of R. albus 8. Data suggest that N34 would confer RalXyn10A the capacity to interact with polysaccharides and components of the cell membrane, enhancing the degradation of the substrate and uptake of the products by the bacterium.

Hongsheng Luo - One of the best experts on this subject based on the ideXlab platform.

  • Is biopolymer hair a multi-responsive smart material?
    Polym. Chem., 2016
    Co-Authors: Xueliang Xiao, Xiaoting Gui, Jinlian Hu, Jing Lu, Hongsheng Luo
    Abstract:

    For thousands of years, animal hairs have been merely considered as textile fibers with outstanding performances such as excellent elasticity and thermal insulation. Only recently, we have obtained indications that animal hair may be a smart natural material which displays shape memory (SM) effects responsive to four types of stimuli: heat, water, Redox Agents and UV-light. These smart functions of animal hair are found to be the result of its three structural components: crystals, and hydrogen (HB) and disulfide (DB) bonds among its intra- and inter-macromolecules. In this paper, camel hair was employed as one typical animal hair to investigate the SM abilities under four types of stimuli, in which the HBs were analyzed by Fourier Transform Infrared spectroscopy and the DBs by Raman spectroscopy, while the Tg and crystal structure of camel hair were determined using differential scanning calorimetry and X-ray diffraction. The shape fixation and recovery ratios were determined using an Instron tensile tester with an environmental chamber. It was discovered that the crystals in hair remain intact under the four stimuli, indicating their role as netpoints for hair SM. Under the stimuli of water and heat, the DBs of hair were characterized as unchangeable, whereas the HBs were found to vary under dry and wet conditions, indicating the roles of DBs as netpoints and HBs as switch units. For UV-light, HBs and crystals were found to be invariable and DBs were converted into thiol groups under a UV stimulus. With a Redox Agent containing reductant ions and aqueous molecules, it was found that DBs and HBs both worked as switch units and crystals acted as netpoints. Thus, the SM mechanism of animal hair was modelled through a twin-netpoint-switch structure. Beneficially, this natural insight can help to inspire applications for making synthetic materials with smarter functions for more environmental adaptability and impactful applications.

Jing Lu - One of the best experts on this subject based on the ideXlab platform.

  • Is biopolymer hair a multi-responsive smart material?
    Polym. Chem., 2016
    Co-Authors: Xueliang Xiao, Xiaoting Gui, Jinlian Hu, Jing Lu, Hongsheng Luo
    Abstract:

    For thousands of years, animal hairs have been merely considered as textile fibers with outstanding performances such as excellent elasticity and thermal insulation. Only recently, we have obtained indications that animal hair may be a smart natural material which displays shape memory (SM) effects responsive to four types of stimuli: heat, water, Redox Agents and UV-light. These smart functions of animal hair are found to be the result of its three structural components: crystals, and hydrogen (HB) and disulfide (DB) bonds among its intra- and inter-macromolecules. In this paper, camel hair was employed as one typical animal hair to investigate the SM abilities under four types of stimuli, in which the HBs were analyzed by Fourier Transform Infrared spectroscopy and the DBs by Raman spectroscopy, while the Tg and crystal structure of camel hair were determined using differential scanning calorimetry and X-ray diffraction. The shape fixation and recovery ratios were determined using an Instron tensile tester with an environmental chamber. It was discovered that the crystals in hair remain intact under the four stimuli, indicating their role as netpoints for hair SM. Under the stimuli of water and heat, the DBs of hair were characterized as unchangeable, whereas the HBs were found to vary under dry and wet conditions, indicating the roles of DBs as netpoints and HBs as switch units. For UV-light, HBs and crystals were found to be invariable and DBs were converted into thiol groups under a UV stimulus. With a Redox Agent containing reductant ions and aqueous molecules, it was found that DBs and HBs both worked as switch units and crystals acted as netpoints. Thus, the SM mechanism of animal hair was modelled through a twin-netpoint-switch structure. Beneficially, this natural insight can help to inspire applications for making synthetic materials with smarter functions for more environmental adaptability and impactful applications.