Sustainable antibacterial–antioxidant films were prepared using in situ graftings of silica nanop... more Sustainable antibacterial–antioxidant films were prepared using in situ graftings of silica nanoparticle (SNP) precursors with covalently attached bioactive agents benzoic acid (ba) or curcumin (cur) on polyvinyl alcohol (PVA). The modified PVA-SNP, PVA-SNP-ba and PVA-SNP-cur films were characterized using spectroscopic, physicochemical and microscopic methods. The prepared films showed excellent antibacterial and antioxidant activity, and increased hydrophobicity providing protection from undesired moisture. The PVA-SNP-ba films completely prevented the growth of the foodborne human pathogen Listeria innocua, whereas PVA-SNP-cur resulted in a 2.5 log reduction of this bacteria. The PVA-SNP-cur and PVA-SNP-ba films showed high antioxidant activity of 15.9 and 14.7 Mm/g TEAC, respectively. The described approach can serve as a generic platform for the formation of PVA-based packaging materials with tailor-made activity tuned by active substituents on silica precursors. Application of...
The olfactory receptor neurons of insects and vertebrates are gated by odorant receptor (OR) prot... more The olfactory receptor neurons of insects and vertebrates are gated by odorant receptor (OR) proteins of which several members have been shown to exhibit remarkable sensitivity and selectivity towards volatile organic compounds of significant importance in the fields of medicine, agriculture and public health. Insect ORs offer intrinsic amplification where a single binding event is transduced into a measurable ionic current. Consequently, insect ORs have great potential as biorecognition elements in many sensor configurations. However, integrating these sensing components onto electronic transducers for the development of biosensors has been marginal due to several drawbacks, including their lipophilic nature, signal transduction mechanism and the limited number of known cognate receptor-ligand pairs. We review the current state of research in this emerging field and highlight the use of a group of indole-sensitive ORs (indolORs) from unexpected sources for the development of biosen...
ABSTRACT Alkaline phosphatase (ALP) is a colorectal cancer biomarker that can be electrochemicall... more ABSTRACT Alkaline phosphatase (ALP) is a colorectal cancer biomarker that can be electrochemically measured from biopsy samples. Since sampled tissues are usually preserved in formalin, it is crucial to know the effect of formaldehyde on ALP activity in the same biochip used for sampled tissue characterization. ALP was reacted with substrate 1-Naphtyl phosphate in a micro-chip with low frequency agitation and the product was oxidized at 300 mV. After exposure to formaldehyde, we identified a sharp initial drop in ALP activity followed by an exponential decrease with the exposure time with an effective time constant of similar to 30 minutes.
ABSTRACT Integrated “tissue on a chip” system with chip-level agitation apparatus has been tested... more ABSTRACT Integrated “tissue on a chip” system with chip-level agitation apparatus has been tested for alkaline phosphatase (ALP) sensing from integrated live tissues on chip. The system was tested and the results are compared to the solutions of a simple 1D models. The models assume electrochemical monitoring of ALP activity with 1-naphtyl phosphate (1-NP) substrate in freshly recovered small tissue samples placed in a micro-electrochemical cell with and without agitation in the 0-12 Hz frequency range. The results indicated on more than an order of magnitude increase in the alpha-naphthol (α-NAP) product oxidation current for samples with agitation compared to non-agitated measurements. The models assume that ALP expressed in the cells (mainly localized in the microvilli of the hepatocytes canalicular membrane) and that part of it is secreted outside of the tissue. The product percolates through the extracellular matrix or leaks out via truncated blood vessels. Once out of the tissue, the product is rapidly distributed throughout the electrolyte and can be oxidized at the working electrode. The measured current and effective charge at long time periods increased as t1/2 and t3/2 respectively. This pointed towards diffusion-limited condition; however, convection should not be excluded. The agitation probably affects the rate of excretion of the product from the tissue and the transfer form the tissue to the electrolyte. Finally, we discuss the applicability of such method for point-of-care application. We present a short discussion and an approach to make such “tissue on a chip” useful for an automated point of care application. To improve accuracy, stability and reproducibility we discuss our approach for a post measurement digital signal processing of the output variable (e.g. current, charge etc.), providing the best signal to noise ratio.
ABSTRACT Coupling of biologically active proteins, for example, enzymes and binding proteins, wit... more ABSTRACT Coupling of biologically active proteins, for example, enzymes and binding proteins, with metals carries huge potential inherent in the integration of these hybrids with miniaturized electronics, medical devices, and in vivo imaging. Here we propose and demonstrate feasibility of the preparation of novel, biologically active silver-avidin hybrids by electroless silver deposition directed to the surface of single, soluble avidin molecules, with retention of their solubility and highly specific biotin binding capacity. The process is based on conjugation of silver ions reducing polymers to avidin surface, followed by the addition of silver ions under mild physiological conditions. The partially overlapping silver patches thus obtained on the protein’s surface provided soluble, biologically active hybrids, retaining their specific biotin binding capability of both low-molecular-weight and high-molecular-weight biotinylated molecules and exhibiting enhanced thermal stability. The hybrids thus obtained were successfully used for molecular imaging of cancer cells prelabeled with biotinylated monoclonal antibody.
A new approach to synthetic chemistry is performed in ultraminiaturized, nanofabricated reaction ... more A new approach to synthetic chemistry is performed in ultraminiaturized, nanofabricated reaction chambers. Using lithographically defined nanowells, we achieve single-point covalent chemistry on hundreds of individual carbon nanotube transistors, providing robust statistics and unprecedented spatial resolution in adduct position. Each device acts as a sensor to detect, in real-time and through quantized changes in conductance, single-point functionalization of the nanotube as well as consecutive chemical reactions, molecular interactions, and molecular conformational changes occurring on the resulting single-molecule probe. In particular, we use a set of sequential bioconjugation reactions to tether a single-strand of DNA to the device and record its repeated, reversible folding into a G-quadruplex structure. The stable covalent tether allows us to measure the same molecule in different solutions, revealing the characteristic increased stability of the G-quadruplex structure in the ...
The study of biomolecular interactions at the single-molecule level holds great potential for bot... more The study of biomolecular interactions at the single-molecule level holds great potential for both basic science and biotechnology applications. Single-molecule studies often rely on fluorescence-based reporting, with signal levels limited by photon emission from single optical reporters. The point-functionalized carbon nanotube transistor, known as the single-molecule field-effect transistor, is a bioelectronics alternative based on intrinsic molecular charge that offers significantly higher signal levels for detection. Such devices are effective for characterizing DNA hybridization kinetics and thermodynamics and enabling emerging applications in genomic identification. In this work, we show that hybridization kinetics can be directly controlled by electrostatic bias applied between the device and the surrounding electrolyte. We perform the first single-molecule experiments demonstrating the use of electrostatics to control molecular binding. Using bias as a proxy for temperature, we demonstrate the feasibility of detecting various concentrations of 20-nt target sequences from the Ebolavirus nucleoprotein gene in a constant-temperature environment.
A novel micro-fluidic whole cell biosensor for toxicity analysis based on bioluminescence detecti... more A novel micro-fluidic whole cell biosensor for toxicity analysis based on bioluminescence detection was developed. The optical part of the biochip was modelled and simulated to optimize the total light collection efficiency and the system response. The optimization elucidated some of the optical aspects of the biochip. A study evaluating the bioluminescence reaction kinetics was performed and revealed the interdependence between the detected bioluminescence and the physical parameters of the introduced toxin.
Whole-cell bio-chips for functional sensing integrate living cells on miniaturized platforms made... more Whole-cell bio-chips for functional sensing integrate living cells on miniaturized platforms made by microsystem-technologies (MST). The cells are integrated, deposited or immersed in a media which is in contact with the chip. The cells behavior is monitored via electrical, electrochemical or optical methods. In this paper we describe such wholecell biochips where the signal is generated due to the genetic response of the cells. The solid-state platform hosts the biological component, i.e. the living cells, and integrates all the required micro-system technologies, i.e. the microelectronics, micro-electro optics, micro-electro or magneto mechanics and micro-fluidics. The genetic response of the cells expresses proteins that generate: a. light by photo-luminescence or bioluminescence, b. electrochemical signal by interaction with a substrate, or c. change in the cell impedance. The cell response is detected by a front end unit that converts it to current or voltage amplifies and filters it. The resultant signal is analyzed and stored for further processing. In this paper we describe three examples of whole-cell bio chips, photo-luminescent, bioluminescent and electrochemical, which are based on the genetic response of genetically modified E. coli microbes integrated on a micro-fluidics MEMS platform. We describe the chip outline as well as the basic modeling scheme of such sensors. We discuss the highlights and problems of such system, from the point of view of micro-system-technology.
A novel micro-fluidic whole cell biosensor for toxicity analysis based on bioluminescence detecti... more A novel micro-fluidic whole cell biosensor for toxicity analysis based on bioluminescence detection was developed. The optical part of the biochip was modelled and simulated to optimize the total light collection efficiency and the system response. The optimization elucidated some of the optical aspects of the biochip. A study evaluating the bioluminescence reaction kinetics was performed and revealed the interdependence between the detected bioluminescence and the physical parameters of the introduced toxin.
Advances in Biochemical Engineering/Biotechnology, 2010
The use of on-chip cellular activity monitoring for biological/chemical sensing is promising for ... more The use of on-chip cellular activity monitoring for biological/chemical sensing is promising for environmental, medical and pharmaceutical applications. The miniaturization revolution in microelectronics is harnessed to provide on-chip detection of cellular activity, opening new horizons for miniature, fast, low cost and portable screening and monitoring devices. In this chapter we survey different on-chip cellular activity detection technologies based on electrochemical, bio-impedance and optical detection. Both prokaryotic and eukaryotic cell-on-chip technologies are mentioned and reviewed.
Sustainable antibacterial–antioxidant films were prepared using in situ graftings of silica nanop... more Sustainable antibacterial–antioxidant films were prepared using in situ graftings of silica nanoparticle (SNP) precursors with covalently attached bioactive agents benzoic acid (ba) or curcumin (cur) on polyvinyl alcohol (PVA). The modified PVA-SNP, PVA-SNP-ba and PVA-SNP-cur films were characterized using spectroscopic, physicochemical and microscopic methods. The prepared films showed excellent antibacterial and antioxidant activity, and increased hydrophobicity providing protection from undesired moisture. The PVA-SNP-ba films completely prevented the growth of the foodborne human pathogen Listeria innocua, whereas PVA-SNP-cur resulted in a 2.5 log reduction of this bacteria. The PVA-SNP-cur and PVA-SNP-ba films showed high antioxidant activity of 15.9 and 14.7 Mm/g TEAC, respectively. The described approach can serve as a generic platform for the formation of PVA-based packaging materials with tailor-made activity tuned by active substituents on silica precursors. Application of...
The olfactory receptor neurons of insects and vertebrates are gated by odorant receptor (OR) prot... more The olfactory receptor neurons of insects and vertebrates are gated by odorant receptor (OR) proteins of which several members have been shown to exhibit remarkable sensitivity and selectivity towards volatile organic compounds of significant importance in the fields of medicine, agriculture and public health. Insect ORs offer intrinsic amplification where a single binding event is transduced into a measurable ionic current. Consequently, insect ORs have great potential as biorecognition elements in many sensor configurations. However, integrating these sensing components onto electronic transducers for the development of biosensors has been marginal due to several drawbacks, including their lipophilic nature, signal transduction mechanism and the limited number of known cognate receptor-ligand pairs. We review the current state of research in this emerging field and highlight the use of a group of indole-sensitive ORs (indolORs) from unexpected sources for the development of biosen...
ABSTRACT Alkaline phosphatase (ALP) is a colorectal cancer biomarker that can be electrochemicall... more ABSTRACT Alkaline phosphatase (ALP) is a colorectal cancer biomarker that can be electrochemically measured from biopsy samples. Since sampled tissues are usually preserved in formalin, it is crucial to know the effect of formaldehyde on ALP activity in the same biochip used for sampled tissue characterization. ALP was reacted with substrate 1-Naphtyl phosphate in a micro-chip with low frequency agitation and the product was oxidized at 300 mV. After exposure to formaldehyde, we identified a sharp initial drop in ALP activity followed by an exponential decrease with the exposure time with an effective time constant of similar to 30 minutes.
ABSTRACT Integrated “tissue on a chip” system with chip-level agitation apparatus has been tested... more ABSTRACT Integrated “tissue on a chip” system with chip-level agitation apparatus has been tested for alkaline phosphatase (ALP) sensing from integrated live tissues on chip. The system was tested and the results are compared to the solutions of a simple 1D models. The models assume electrochemical monitoring of ALP activity with 1-naphtyl phosphate (1-NP) substrate in freshly recovered small tissue samples placed in a micro-electrochemical cell with and without agitation in the 0-12 Hz frequency range. The results indicated on more than an order of magnitude increase in the alpha-naphthol (α-NAP) product oxidation current for samples with agitation compared to non-agitated measurements. The models assume that ALP expressed in the cells (mainly localized in the microvilli of the hepatocytes canalicular membrane) and that part of it is secreted outside of the tissue. The product percolates through the extracellular matrix or leaks out via truncated blood vessels. Once out of the tissue, the product is rapidly distributed throughout the electrolyte and can be oxidized at the working electrode. The measured current and effective charge at long time periods increased as t1/2 and t3/2 respectively. This pointed towards diffusion-limited condition; however, convection should not be excluded. The agitation probably affects the rate of excretion of the product from the tissue and the transfer form the tissue to the electrolyte. Finally, we discuss the applicability of such method for point-of-care application. We present a short discussion and an approach to make such “tissue on a chip” useful for an automated point of care application. To improve accuracy, stability and reproducibility we discuss our approach for a post measurement digital signal processing of the output variable (e.g. current, charge etc.), providing the best signal to noise ratio.
ABSTRACT Coupling of biologically active proteins, for example, enzymes and binding proteins, wit... more ABSTRACT Coupling of biologically active proteins, for example, enzymes and binding proteins, with metals carries huge potential inherent in the integration of these hybrids with miniaturized electronics, medical devices, and in vivo imaging. Here we propose and demonstrate feasibility of the preparation of novel, biologically active silver-avidin hybrids by electroless silver deposition directed to the surface of single, soluble avidin molecules, with retention of their solubility and highly specific biotin binding capacity. The process is based on conjugation of silver ions reducing polymers to avidin surface, followed by the addition of silver ions under mild physiological conditions. The partially overlapping silver patches thus obtained on the protein’s surface provided soluble, biologically active hybrids, retaining their specific biotin binding capability of both low-molecular-weight and high-molecular-weight biotinylated molecules and exhibiting enhanced thermal stability. The hybrids thus obtained were successfully used for molecular imaging of cancer cells prelabeled with biotinylated monoclonal antibody.
A new approach to synthetic chemistry is performed in ultraminiaturized, nanofabricated reaction ... more A new approach to synthetic chemistry is performed in ultraminiaturized, nanofabricated reaction chambers. Using lithographically defined nanowells, we achieve single-point covalent chemistry on hundreds of individual carbon nanotube transistors, providing robust statistics and unprecedented spatial resolution in adduct position. Each device acts as a sensor to detect, in real-time and through quantized changes in conductance, single-point functionalization of the nanotube as well as consecutive chemical reactions, molecular interactions, and molecular conformational changes occurring on the resulting single-molecule probe. In particular, we use a set of sequential bioconjugation reactions to tether a single-strand of DNA to the device and record its repeated, reversible folding into a G-quadruplex structure. The stable covalent tether allows us to measure the same molecule in different solutions, revealing the characteristic increased stability of the G-quadruplex structure in the ...
The study of biomolecular interactions at the single-molecule level holds great potential for bot... more The study of biomolecular interactions at the single-molecule level holds great potential for both basic science and biotechnology applications. Single-molecule studies often rely on fluorescence-based reporting, with signal levels limited by photon emission from single optical reporters. The point-functionalized carbon nanotube transistor, known as the single-molecule field-effect transistor, is a bioelectronics alternative based on intrinsic molecular charge that offers significantly higher signal levels for detection. Such devices are effective for characterizing DNA hybridization kinetics and thermodynamics and enabling emerging applications in genomic identification. In this work, we show that hybridization kinetics can be directly controlled by electrostatic bias applied between the device and the surrounding electrolyte. We perform the first single-molecule experiments demonstrating the use of electrostatics to control molecular binding. Using bias as a proxy for temperature, we demonstrate the feasibility of detecting various concentrations of 20-nt target sequences from the Ebolavirus nucleoprotein gene in a constant-temperature environment.
A novel micro-fluidic whole cell biosensor for toxicity analysis based on bioluminescence detecti... more A novel micro-fluidic whole cell biosensor for toxicity analysis based on bioluminescence detection was developed. The optical part of the biochip was modelled and simulated to optimize the total light collection efficiency and the system response. The optimization elucidated some of the optical aspects of the biochip. A study evaluating the bioluminescence reaction kinetics was performed and revealed the interdependence between the detected bioluminescence and the physical parameters of the introduced toxin.
Whole-cell bio-chips for functional sensing integrate living cells on miniaturized platforms made... more Whole-cell bio-chips for functional sensing integrate living cells on miniaturized platforms made by microsystem-technologies (MST). The cells are integrated, deposited or immersed in a media which is in contact with the chip. The cells behavior is monitored via electrical, electrochemical or optical methods. In this paper we describe such wholecell biochips where the signal is generated due to the genetic response of the cells. The solid-state platform hosts the biological component, i.e. the living cells, and integrates all the required micro-system technologies, i.e. the microelectronics, micro-electro optics, micro-electro or magneto mechanics and micro-fluidics. The genetic response of the cells expresses proteins that generate: a. light by photo-luminescence or bioluminescence, b. electrochemical signal by interaction with a substrate, or c. change in the cell impedance. The cell response is detected by a front end unit that converts it to current or voltage amplifies and filters it. The resultant signal is analyzed and stored for further processing. In this paper we describe three examples of whole-cell bio chips, photo-luminescent, bioluminescent and electrochemical, which are based on the genetic response of genetically modified E. coli microbes integrated on a micro-fluidics MEMS platform. We describe the chip outline as well as the basic modeling scheme of such sensors. We discuss the highlights and problems of such system, from the point of view of micro-system-technology.
A novel micro-fluidic whole cell biosensor for toxicity analysis based on bioluminescence detecti... more A novel micro-fluidic whole cell biosensor for toxicity analysis based on bioluminescence detection was developed. The optical part of the biochip was modelled and simulated to optimize the total light collection efficiency and the system response. The optimization elucidated some of the optical aspects of the biochip. A study evaluating the bioluminescence reaction kinetics was performed and revealed the interdependence between the detected bioluminescence and the physical parameters of the introduced toxin.
Advances in Biochemical Engineering/Biotechnology, 2010
The use of on-chip cellular activity monitoring for biological/chemical sensing is promising for ... more The use of on-chip cellular activity monitoring for biological/chemical sensing is promising for environmental, medical and pharmaceutical applications. The miniaturization revolution in microelectronics is harnessed to provide on-chip detection of cellular activity, opening new horizons for miniature, fast, low cost and portable screening and monitoring devices. In this chapter we survey different on-chip cellular activity detection technologies based on electrochemical, bio-impedance and optical detection. Both prokaryotic and eukaryotic cell-on-chip technologies are mentioned and reviewed.
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Papers by Sefi Vernick