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Fernando Patolsky

Publications and source records attributed to Fernando Patolsky.

At least 19 recordsLinked to original sources
PubMed2006

Detection, stimulation, and inhibition of neuronal signals with high-density nanowire transistor arrays.

We report electrical properties of hybrid structures consisting of arrays of nanowire field-effect transistors integrated with the individual axons and dendrites of live mammalian neurons, where each nanoscale junction can be used for spatially resolved, highly sensitive detection, stimulation, and/or inhibition of neuronal signal propagation. Arrays of nanowire-neuron junctions enable simultaneous measurement of the rate, amplitude, and shape of signals propagating along individual axons and dendrites. The configuration of nanowire-axon junctions in arrays, as both inputs and outputs, makes possible controlled studies of partial to complete inhibition of signal propagation by both local electrical and chemical stimuli. In addition, nanowire-axon junction arrays were integrated and tested at a level of at least 50 "artificial synapses" per neuron.

Action Potentials↗
PubMed2005

Multiplexed electrical detection of cancer markers with nanowire sensor arrays.

We describe highly sensitive, label-free, multiplexed electrical detection of cancer markers using silicon-nanowire field-effect devices in which distinct nanowires and surface receptors are incorporated into arrays. Protein markers were routinely detected at femtomolar concentrations with high selectivity, and simultaneous incorporation of control nanowires enabled discrimination against false positives. Nanowire arrays allowed highly selective and sensitive multiplexed detection of prostate specific antigen (PSA), PSA-alpha1-antichymotrypsin, carcinoembryonic antigen and mucin-1, including detection to at least 0.9 pg/ml in undiluted serum samples. In addition, nucleic acid receptors enabled real-time assays of the binding, activity and small-molecule inhibition of telomerase using unamplified extracts from as few as ten tumor cells. The capability for multiplexed real-time monitoring of protein markers and telomerase activity with high sensitivity and selectivity in clinically relevant samples opens up substantial possibilities for diagnosis and treatment of cancer and other complex diseases.

Biomarkers, Tumor↗
PubMed2004

Electrical detection of single viruses.

We report direct, real-time electrical detection of single virus particles with high selectivity by using nanowire field effect transistors. Measurements made with nanowire arrays modified with antibodies for influenza A showed discrete conductance changes characteristic of binding and unbinding in the presence of influenza A but not paramyxovirus or adenovirus. Simultaneous electrical and optical measurements using fluorescently labeled influenza A were used to demonstrate conclusively that the conductance changes correspond to binding/unbinding of single viruses at the surface of nanowire devices. pH-dependent studies further show that the detection mechanism is caused by a field effect, and that the nanowire devices can be used to determine rapidly isoelectric points and variations in receptor-virus binding kinetics for different conditions. Lastly, studies of nanowire devices modified with antibodies specific for either influenza or adenovirus show that multiple viruses can be selectively detected in parallel. The possibility of large-scale integration of these nanowire devices suggests potential for simultaneous detection of a large number of distinct viral threats at the single virus level.

Animals↗
PubMed2004

Actin-based metallic nanowires as bio-nanotransporters.

The synthesis of conductive nanowires or patterned conductive nanoelements is a challenging goal for the future fabrication of nanoscale circuitry. Similarly, the realization of nanoscale mechanics might introduce a new facet to the area of nanobiotechnology. Here we report on the design of conductive and patterned actin-based gold nanowires, and on the ATP-driven motility of the nano-objects. The polymerization of G-actin labelled with Au nanoparticles, followed by the catalytic enlargement of the nanoparticles, yields gold wires (1-4 microm long and 80-200 nm high) exhibiting high electrical conductivity. The polymerization of the Au nanoparticle/G-actin monomer followed by the polymerization of free G-actin, or alternatively the polymerization of the Au-nanoparticle-labelled G-actin on polymerized F-actin followed by the catalytic enlargement of the particles, yields patterned actin-Au wire-actin or Au wire-actin-Au wire nanostructures, respectively. We demonstrate the ATP-fuelled motility of the actin-Au wire-actin filaments on a myosin interface. These actin-based metallic wires and their nanotransporting funcionality introduce new concepts for developing biological/inorganic hybrid devices.

Actins↗
PubMed2004

Amplified telomerase analysis by using rotating magnetic particles: the rapid and sensitive detection of cancer cells.

A highly sensitive telomerase detection method that involves amplified telomerase analysis and the use of rotating magnetic particles has been developed. Magnetic particles, functionalized with a primer (1) that is recognized by telomerase, are mixed with a nucleotide mixture that includes biotinylated-dUTP, and telomerase-induced elongation of the primers proceeds with simultaneous biotin incorporation. Avidin-Horseradish peroxidase conjugate, coupled to biotin labels, yields the biocatalytic functional particles. Mixing the resulting particles with naphthoquinone-modified magnetic particles enables the optoelectronic detection of telomerase. Attraction of the magnetic particles to an electrode, followed by rotation of the particles, causes the electrocatalytic reduction of O(2) to H(2)O(2) and HRP-catalyzed oxidation of luminol (3); this results in chemilumunescence. The intensity of the emitted light depends on the telomerase content of the sample and the rotation speed of the particles. A minimum number of 10 cancer cells could be detected.

Adenocarcinoma↗
PubMed2004

Enzyme-catalyzed bio-pumping of electrons into au-nanoparticles: a surface plasmon resonance and electrochemical study.

The enzyme glucose oxidase (GOx) is reconstituted on a flavin adenin dinucleotide (FAD, 1) cofactor-functionalized Au-nanoparticle (Au-NP), 1.4 nm, and the GOx/Au-NP hybrid is linked to a bulk Au-electrode by a short dithiol, 1,4-benzenedithiol (2), or a long dithiol, 1,9-nonanedithiol (3), monolayer. The reconstituted GOx/Au-NP hybrid system exhibits electrical communication between the enzyme redox cofactor and the Au-NP core. Because the thiol monolayers provide a barrier for electron tunneling, the electron transfer occurring upon the biocatalytic oxidation of glucose results in the Au-NPs charging. The charging of the Au-NPs alters the plasma frequency and the dielectric constant of the Au-NPs, thus leading to the changes of the dielectric constant of the interface. These are reflected in pronounced shifts of the plasmon angle, theta(P), in the surface plasmon resonance (SPR) spectra. As the biocatalytic charging phenomenon is controlled by the concentration of glucose, the changes in the theta(P) values correlate with the concentration of glucose. The biocatalytic charging process is characterized by following the differential capacitance of the GOx/Au-NP interface and by monitoring the potential generated on the bulk Au-electrode. The charging of the GOx/Au-NPs is also accomplished in the absence of glucose by the application of an external potential on the electrode, that resulted in similar plasmon angle shifts. The results allowed us to estimate the number of electrons stored per Au-NP at variable concentrations of glucose in the presence of the two different thiol linkers.

Aspergillus niger↗
PubMed2004

Magneto-mechanical detection of nucleic acids and telomerase activity in cancer cells.

The ultra-sensitive magneto-mechanical detection of DNA, single-base-mismatches in nucleic acids, and the assay of telomerase activity are accomplished by monitoring the magnetically induced deflection of a cantilever functionalized with magnetic beads associated with the biosensing interface. The analyzed M13phi DNA hybridized with the nucleic acid-functionalized magnetic beads is replicated in the presence of dNTPs that include biotin-labeled dUTP. The resulting beads are attached to an avidin-coated cantilever, and the modified cantilever is deflected by an external magnetic field. Similarly, telomerization of nucleic acid-modified magnetic beads in the presence of dNTPs, biotin-labeled dUTP, and telomerase from cancer cell extracts and the subsequent association of the magnetic beads to the cantilever surface results in the lever deflection by an external magnetic field. M13phi DNA is sensed with a sensitivity limit of 7.1 x 10(-20) M by the magneto-mechanical detection method.

Base Pair Mismatch↗
PubMed2003

"Plugging into Enzymes": nanowiring of redox enzymes by a gold nanoparticle.

The reconstitution of an apo-flavoenzyme, apo-glucose oxidase, on a 1.4-nanometer gold nanocrystal functionalized with the cofactor flavin adenine dinucleotide and integrated into a conductive film yields a bioelectrocatalytic system with exceptional electrical contact with the electrode support. The electron transfer turnover rate of the reconstituted bioelectrocatalyst is approximately 5000 per second, compared with the rate at which molecular oxygen, the natural cosubstrate of the enzyme, accepts electrons (approximately 700 per second). The gold nanoparticle acts as an electron relay or "electrical nanoplug" for the alignment of the enzyme on the conductive support and for the electrical wiring of its redox-active center.

Apoenzymes↗
PubMed2003

Highly sensitive amplified electronic detection of DNA by biocatalyzed precipitation of an insoluble product onto electrodes.

The amplified detection of a target DNA, based on the alkaline phosphatase oxidative hydrolysis of the soluble 5-bromo-4-chloro-3-indoyl phosphate to the insoluble indigo product as an amplification path, is addressed by two different sensing configurations. The accumulation of the insoluble product on Au electrodes or Au/quartz crystals alters the interfacial electron-transfer resistance at the Au electrode or the mass associated with the piezoelectric crystal, thus enabling the quantitative transduction of the DNA sensing by Faradaic impedance spectroscopy or microgravimetric quartz crystal microbalance measurements, respectively. One sensing configuration involves the association of a complex consisting of the target DNA and a biotinylated oligonucleotide to the functionalized transducers. The binding of the avidin/alkaline phosphatase conjugate to the sensing interface followed by the biocatalyzed precipitation provides the amplification path for the analysis of the target DNA. This analysis scheme was used to sense the target DNA with a sensitivity limit that corresponds to 5 x 10(-14) M. The second amplified detection scheme involves the use of a nucleic-acid-functionalized alkaline phosphatase as a biocatalytic conjugate for the precipitation of the insoluble product. Following this scheme, the functionalized transducers are interacted with the analyzed sample that was pretreated with the oligonucleotide-modified alkaline phosphatase, followed by the biocatalyzed precipitation as the amplification route for the analysis of the target DNA. By the use of this configuration, a detection limit corresponding to 5 x 10(-13) M was achieved. Real clinical samples of the Tay-Sachs genetic disorder were easily analyzed by the developed detection routes.

Alkaline Phosphatase↗
PubMed2002

Electrical contacting of glucose dehydrogenase by the reconstitution of a pyrroloquinoline quinone-functionalized polyaniline film associated with an Au-electrode: an in situ electrochemical SPR study.

A novel method to generate an integrated electrically contacted glucose dehydrogenase electrode by the surface reconstitution of the apo-enzyme on a pyrroloquinoline quinone (PQQ)-modified polyaniline is described. In situ electrochemical surface plasmon resonance (SPR) is used to characterize the bioelectrocatalytic functions of the system.

Aniline Compounds↗