Harold Monbouquette | University of California, Los Angeles (original) (raw)

Papers by Harold Monbouquette

Research paper thumbnail of Microcontact printing of choline oxidase using a polycation-functionalized zwitterionic polymer as enzyme immobilization matrix

The Analyst

Microcontact printing of choline oxidase on an implantable, microelectrode array probe using an “... more Microcontact printing of choline oxidase on an implantable, microelectrode array probe using an “ink” based on the novel polymer, PMPC-g-PAH, to create high-performance choline biosensors.

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Research paper thumbnail of Identification and Characterization of a Novel Ferric Reductase from the Hyperthermophilic Archaeon Archaeoglobus fulgidus

Journal of Biological Chemistry, Dec 1, 1999

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Research paper thumbnail of Electric field modulated optical saturation absorption of CdSe quantum dots

Bulletin of the American Physical Society, Mar 22, 2005

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Research paper thumbnail of Simulated Performance of Electroenzymatic Glutamate Biosensors In Vivo Illuminates the Complex Connection to Calibration In Vitro

ACS Chemical Neuroscience, Nov 4, 2021

Detailed simulations show that the relationship between electroenzymatic glutamate (Glut) sensor ... more Detailed simulations show that the relationship between electroenzymatic glutamate (Glut) sensor performance in vitro and that modeled in vivo is complicated by the influence of both resistances to mass transfer and clearance rates of Glut and H2O2 in the brain extracellular space (ECS). Mathematical modeling provides a powerful means to illustrate how these devices are expected to respond to a variety of conditions in vivo in ways that cannot be accomplished readily using existing experimental techniques. Through the use of transient model simulations in one spatial dimension, it is shown that the sensor response in vivo may exhibit much greater dependence on H2O2 mass transfer and clearance in the surrounding tissue than previously thought. This dependence may lead to sensor signals more than double the expected values (based on prior sensor calibration in vitro) for Glut release events within a few microns of the sensor surface. The sensor response in general is greatly affected by the distance between the device and location of Glut release, and apparent concentrations reported by simulated sensors consistently are well below the actual Glut levels for events occurring at distances greater than a few microns. Simulations of transient Glut concentrations, including a physiologically relevant bolus release, indicate that detection of Glut signaling likely is limited to events within 30 μm of the sensor surface based on representative sensor detection limits. It follows that important limitations also exist with respect to interpretation of decays in sensor signals, including relation of such data to actual Glut concentration declines in vivo. Thus, the use of sensor signal data to determine quantitatively the rates of Glut uptake from the brain ECS likely is problematic. The model is designed to represent a broad range of relevant physiological conditions, and although limited to one dimension, provides much needed guidance regarding the interpretation in general of electroenzymatic sensor data gathered in vivo.

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Research paper thumbnail of alanine dehydrogenase dimer w/bound NAD (archaeal)

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Research paper thumbnail of Flexible and Implantable Polyimide Aptamer-Field-Effect Transistor Biosensors

ACS Sensors, Nov 18, 2022

Monitoring neurochemical signaling across timescales is critical to understanding how brains enco... more Monitoring neurochemical signaling across timescales is critical to understanding how brains encode and store information. Flexible (vs. stiff) devices have been shown to improve in vivo monitoring, particularly over longer times, by reducing tissue damage and immunological responses. Here, we report our initial steps toward developing flexible and implantable neuroprobes with aptamer-field-effect transistor (FET) biosensors for neurotransmitter monitoring. A high-throughput process was developed to fabricate thin, flexible polyimide probes using micro-electro-mechanical-system (MEMS) technologies, where 150 flexible probes were fabricated on each 4-inch Si wafer. Probes were 150-μm wide and 7-μm thick with two FETs per tip. The bending stiffness was 1.2 × 10−11 N·m2. Semiconductor thin films (3-nm In2O3) were functionalized with DNA aptamers for target recognition, which produces aptamer conformational rearrangements detected via changes in FET conductance. Flexible aptamer-FET neuroprobes detected serotonin at femtomolar concentrations in high-ionic strength artificial cerebrospinal fluid. A straightforward implantation process was developed, where micro-fabricated Si carrier devices assisted with implantation such that flexible neuroprobes detected physiological relevant serotonin in a tissue-hydrogel brain mimic.

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Research paper thumbnail of ChemInform Abstract: An Efficient Synthesis of a Class of Heterobifunctional Photo-reactive Crosslinkers, Labels, and Probes

ChemInform, May 25, 2010

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Research paper thumbnail of Multi-Functional Neural Probes for Pharmacological and Optogenetic Manipulation and Detection of Neurotransmitter Release

2018 IEEE SENSORS, 2018

The ability to monitor neurotransmitter release in freely behaving animals is key to understandin... more The ability to monitor neurotransmitter release in freely behaving animals is key to understanding neuronal processes underlying complex behaviors. Commonly used methods either offer rapid measurements of a single analyte (e.g., fast-scan cyclic voltammetry) or provide multiple analyte measurement with insufficient temporal resolution (microdialysis). However, behaviors are controlled by neuronal networks employing multiple neurotransmitters and neuromodulators. Efforts to understand how neurons within these networks interact to control behavior will be greatly facilitated by a means with which to both modulate and measure multiple neuroactive molecules simultaneously and in near-real time. To this end, we are developing MEA enzymatic biosensors with built-in microfluidics and optical guides for pharmacological and optogenetic control of transmitter release in brain tissue.

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Research paper thumbnail of Size-Controlled Synthesis of Cds Nanocrystals in Vesicles Confirmed in Situby Cryo-Transmission Electron Microscopy

Microscopy and Microanalysis, 1997

Size-quantized CdS nanocrystals, synthesized within phosphatidylcholine (PC) vesicles by reaction... more Size-quantized CdS nanocrystals, synthesized within phosphatidylcholine (PC) vesicles by reaction compartmentalization, were observed in situ to confirm the proposed method of formation and to investigate the concept of membrane-mediated crystal growth. Vesicle solutions representing three different CdS nanocrystal sizes, and a solution containing unreacted CdCl2 inside vesicles, were analyzed using cryo-transmission electron microscopy (cryo-TEM). Cryo-TEM has proved capable of resolving both the vesicle bilayer and the encapsulated nanocrystal, and yields previously unknown positional information for the crystal in relation to the bilayer.Egg-PC vesicles containing Cd2+ were formed by detergent depletion, yielding vesicles of uniform size and a defined internal Cd2+ concentration. External Cd2+ was removed from the solution by cation exchange. Ammonium sulfide was added to the vesicle dispersion to produce nanocrystals via diffusion of S2- across the vesicle membrane. Particle siz...

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Research paper thumbnail of Flexible, multifunctional neural probe with liquid metal enabled, ultra-large tunable stiffness for deep-brain chemical sensing and agent delivery

Biosensors and Bioelectronics, 2019

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Research paper thumbnail of Corrigendum: Basolateral amygdala rapid glutamate release encodes an outcome-specific representation vital for reward-predictive cues to selectively invigorate reward-seeking actions

Scientific reports, Jan 15, 2016

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Research paper thumbnail of Electroenzymatic Sensing of Fructose Using Fructose Dehydrogenase Immobilized in a Self-Assembled Monolayer on Gold

ACS Symposium Series, 1996

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Research paper thumbnail of Selective and regenerable metal-sorbing vesicles for metal ion recovery

Phospholipid vesicles or liposomes mimic closely biological cell membranes, and unilamellar lipid... more Phospholipid vesicles or liposomes mimic closely biological cell membranes, and unilamellar lipid vesicles harboring a lipophilic ionophore in the capsule wall and encapsulating a strong water-soluble metal chelating agent rapidly take up and concentrate metal cations. This capability has been exploited in the design of metal-sorbing vesicles (MSVs) for the selective removal of heavy metal cations such as Cu{sup 2+} and Pb{sup 2+} from dilute aqueous solution. MSVs present exposed membrane surface areas of 3000-30,000 m{sup 2}/L at vesicle concentrations of 1-10% w/v, exhibit high surface area to encapsulated volume ratios of 50 or more m{sup 2}/mL, and have exceedingly-small membrane wall thicknesses of 3-5 nm. These attributes give rise to very rapid metal ion extraction rates and high concentration factors. MSVs have been polymerized for enhanced stability, and schemes for their use in continuous metal ion recovery processes have been developed. 31 refs., 2 figs.

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Research paper thumbnail of Dynamics of Terminally Anchored Polymeric Chains

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Research paper thumbnail of Correction: An amplification-free, 16S rRNA test for Neisseria gonorrhoeae in urine

Sensors & Diagnostics

Correction for ‘An amplification-free, 16S rRNA test for Neisseria gonorrhoeae in urine’ by Zhenr... more Correction for ‘An amplification-free, 16S rRNA test for Neisseria gonorrhoeae in urine’ by Zhenrong Zheng et al., Sens. Diagn., 2023, 2, 163–167, https://doi.org/10.1039/d2sd00128d.

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Research paper thumbnail of Photocatalytic reduction of aromatic azides to amines using CdS and CdSe nanoparticles

Photochemical & Photobiological Sciences, 2004

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Research paper thumbnail of An amplification-free, 16S rRNA test for Neisseria gonorrhoeae in urine

Sensors & Diagnostics

Conductometric detection of N. gonorrhoeae 16S rRNA (green) by blockade of glass pores. Polystyre... more Conductometric detection of N. gonorrhoeae 16S rRNA (green) by blockade of glass pores. Polystyrene beads conjugated with PNA probe (orange) are charge neutral but acquire negative charge and electrophoretic mobility upon hybridization of rRNA.

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Research paper thumbnail of Implantable aptamer–field-effect transistor neuroprobes for in vivo neurotransmitter monitoring

Science Advances, 2021

Implantable aptamer transistor probes for in vivo neurotransmitter monitoring advance brain activ... more Implantable aptamer transistor probes for in vivo neurotransmitter monitoring advance brain activity recording.

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Research paper thumbnail of Investigating Antibody Access to Adsorbed Protein Nanocapsule Interiors Using the Quartz Crystal Microbalance and Surface Plasmon Resonance

Vaults are nanoscale, ribonucleoprotein capsules (41 nm × 41 nm × 72.5 nm [1]) comprised primaril... more Vaults are nanoscale, ribonucleoprotein capsules (41 nm × 41 nm × 72.5 nm [1]) comprised primarily of 96 self-assembled copies of one 96 kDa protein, termed MVP (major vault protein). When deposited on polylysine-coated mica and imaged using cryoelectron microscopy, vaults appear to “open” into flower-like structures with eight rectangular ‘petals’ [2]. Upon closer examination, each ‘flower’ consists of a central ring with hooks that attach each petal to the center. The flowers are usually seen in pairs, suggesting that each whole vault is composed of two flowers, folded so that the ends of their petals touch. It is likely that vaults in cells open and close in response to cellular signals, reversibly encapsulating and releasing their contents. However, whether vaults open into flower-like structures in vivo is unknown.

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Research paper thumbnail of Nucleic acid amplification-free detection of DNA and RNA at ultralow concentration

Current Opinion in Biotechnology, 2021

The broad spectrum of approaches for nucleic acid amplification-free detection of DNA and RNA at ... more The broad spectrum of approaches for nucleic acid amplification-free detection of DNA and RNA at single-digit attomolar (10-18 M) concentration and lower is reviewed. These low concentrations correspond roughly to the most clinically desirable detection range for pathogen-specific nucleic acid as well as the detection limits of commercially available, nucleic acid amplification tests based primarily on polymerase chain reaction (PCR). The need for more rapid and inexpensive, yet still highly accurate tests, has become evident during the pandemic. It is expected that publication of reports describing improved tests will accelerate soon, and this review covers the wide variety of detection methods based on both optical and electrical measurements that have been conceived over recent years, enabled generally by the advent of nanotechnology.

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Research paper thumbnail of Microcontact printing of choline oxidase using a polycation-functionalized zwitterionic polymer as enzyme immobilization matrix

The Analyst

Microcontact printing of choline oxidase on an implantable, microelectrode array probe using an “... more Microcontact printing of choline oxidase on an implantable, microelectrode array probe using an “ink” based on the novel polymer, PMPC-g-PAH, to create high-performance choline biosensors.

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Research paper thumbnail of Identification and Characterization of a Novel Ferric Reductase from the Hyperthermophilic Archaeon Archaeoglobus fulgidus

Journal of Biological Chemistry, Dec 1, 1999

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Research paper thumbnail of Electric field modulated optical saturation absorption of CdSe quantum dots

Bulletin of the American Physical Society, Mar 22, 2005

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Simulated Performance of Electroenzymatic Glutamate Biosensors In Vivo Illuminates the Complex Connection to Calibration In Vitro

ACS Chemical Neuroscience, Nov 4, 2021

Detailed simulations show that the relationship between electroenzymatic glutamate (Glut) sensor ... more Detailed simulations show that the relationship between electroenzymatic glutamate (Glut) sensor performance in vitro and that modeled in vivo is complicated by the influence of both resistances to mass transfer and clearance rates of Glut and H2O2 in the brain extracellular space (ECS). Mathematical modeling provides a powerful means to illustrate how these devices are expected to respond to a variety of conditions in vivo in ways that cannot be accomplished readily using existing experimental techniques. Through the use of transient model simulations in one spatial dimension, it is shown that the sensor response in vivo may exhibit much greater dependence on H2O2 mass transfer and clearance in the surrounding tissue than previously thought. This dependence may lead to sensor signals more than double the expected values (based on prior sensor calibration in vitro) for Glut release events within a few microns of the sensor surface. The sensor response in general is greatly affected by the distance between the device and location of Glut release, and apparent concentrations reported by simulated sensors consistently are well below the actual Glut levels for events occurring at distances greater than a few microns. Simulations of transient Glut concentrations, including a physiologically relevant bolus release, indicate that detection of Glut signaling likely is limited to events within 30 μm of the sensor surface based on representative sensor detection limits. It follows that important limitations also exist with respect to interpretation of decays in sensor signals, including relation of such data to actual Glut concentration declines in vivo. Thus, the use of sensor signal data to determine quantitatively the rates of Glut uptake from the brain ECS likely is problematic. The model is designed to represent a broad range of relevant physiological conditions, and although limited to one dimension, provides much needed guidance regarding the interpretation in general of electroenzymatic sensor data gathered in vivo.

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Research paper thumbnail of alanine dehydrogenase dimer w/bound NAD (archaeal)

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Flexible and Implantable Polyimide Aptamer-Field-Effect Transistor Biosensors

ACS Sensors, Nov 18, 2022

Monitoring neurochemical signaling across timescales is critical to understanding how brains enco... more Monitoring neurochemical signaling across timescales is critical to understanding how brains encode and store information. Flexible (vs. stiff) devices have been shown to improve in vivo monitoring, particularly over longer times, by reducing tissue damage and immunological responses. Here, we report our initial steps toward developing flexible and implantable neuroprobes with aptamer-field-effect transistor (FET) biosensors for neurotransmitter monitoring. A high-throughput process was developed to fabricate thin, flexible polyimide probes using micro-electro-mechanical-system (MEMS) technologies, where 150 flexible probes were fabricated on each 4-inch Si wafer. Probes were 150-μm wide and 7-μm thick with two FETs per tip. The bending stiffness was 1.2 × 10−11 N·m2. Semiconductor thin films (3-nm In2O3) were functionalized with DNA aptamers for target recognition, which produces aptamer conformational rearrangements detected via changes in FET conductance. Flexible aptamer-FET neuroprobes detected serotonin at femtomolar concentrations in high-ionic strength artificial cerebrospinal fluid. A straightforward implantation process was developed, where micro-fabricated Si carrier devices assisted with implantation such that flexible neuroprobes detected physiological relevant serotonin in a tissue-hydrogel brain mimic.

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Research paper thumbnail of ChemInform Abstract: An Efficient Synthesis of a Class of Heterobifunctional Photo-reactive Crosslinkers, Labels, and Probes

ChemInform, May 25, 2010

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Research paper thumbnail of Multi-Functional Neural Probes for Pharmacological and Optogenetic Manipulation and Detection of Neurotransmitter Release

2018 IEEE SENSORS, 2018

The ability to monitor neurotransmitter release in freely behaving animals is key to understandin... more The ability to monitor neurotransmitter release in freely behaving animals is key to understanding neuronal processes underlying complex behaviors. Commonly used methods either offer rapid measurements of a single analyte (e.g., fast-scan cyclic voltammetry) or provide multiple analyte measurement with insufficient temporal resolution (microdialysis). However, behaviors are controlled by neuronal networks employing multiple neurotransmitters and neuromodulators. Efforts to understand how neurons within these networks interact to control behavior will be greatly facilitated by a means with which to both modulate and measure multiple neuroactive molecules simultaneously and in near-real time. To this end, we are developing MEA enzymatic biosensors with built-in microfluidics and optical guides for pharmacological and optogenetic control of transmitter release in brain tissue.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Size-Controlled Synthesis of Cds Nanocrystals in Vesicles Confirmed in Situby Cryo-Transmission Electron Microscopy

Microscopy and Microanalysis, 1997

Size-quantized CdS nanocrystals, synthesized within phosphatidylcholine (PC) vesicles by reaction... more Size-quantized CdS nanocrystals, synthesized within phosphatidylcholine (PC) vesicles by reaction compartmentalization, were observed in situ to confirm the proposed method of formation and to investigate the concept of membrane-mediated crystal growth. Vesicle solutions representing three different CdS nanocrystal sizes, and a solution containing unreacted CdCl2 inside vesicles, were analyzed using cryo-transmission electron microscopy (cryo-TEM). Cryo-TEM has proved capable of resolving both the vesicle bilayer and the encapsulated nanocrystal, and yields previously unknown positional information for the crystal in relation to the bilayer.Egg-PC vesicles containing Cd2+ were formed by detergent depletion, yielding vesicles of uniform size and a defined internal Cd2+ concentration. External Cd2+ was removed from the solution by cation exchange. Ammonium sulfide was added to the vesicle dispersion to produce nanocrystals via diffusion of S2- across the vesicle membrane. Particle siz...

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Research paper thumbnail of Flexible, multifunctional neural probe with liquid metal enabled, ultra-large tunable stiffness for deep-brain chemical sensing and agent delivery

Biosensors and Bioelectronics, 2019

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Research paper thumbnail of Corrigendum: Basolateral amygdala rapid glutamate release encodes an outcome-specific representation vital for reward-predictive cues to selectively invigorate reward-seeking actions

Scientific reports, Jan 15, 2016

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Research paper thumbnail of Electroenzymatic Sensing of Fructose Using Fructose Dehydrogenase Immobilized in a Self-Assembled Monolayer on Gold

ACS Symposium Series, 1996

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Research paper thumbnail of Selective and regenerable metal-sorbing vesicles for metal ion recovery

Phospholipid vesicles or liposomes mimic closely biological cell membranes, and unilamellar lipid... more Phospholipid vesicles or liposomes mimic closely biological cell membranes, and unilamellar lipid vesicles harboring a lipophilic ionophore in the capsule wall and encapsulating a strong water-soluble metal chelating agent rapidly take up and concentrate metal cations. This capability has been exploited in the design of metal-sorbing vesicles (MSVs) for the selective removal of heavy metal cations such as Cu{sup 2+} and Pb{sup 2+} from dilute aqueous solution. MSVs present exposed membrane surface areas of 3000-30,000 m{sup 2}/L at vesicle concentrations of 1-10% w/v, exhibit high surface area to encapsulated volume ratios of 50 or more m{sup 2}/mL, and have exceedingly-small membrane wall thicknesses of 3-5 nm. These attributes give rise to very rapid metal ion extraction rates and high concentration factors. MSVs have been polymerized for enhanced stability, and schemes for their use in continuous metal ion recovery processes have been developed. 31 refs., 2 figs.

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Research paper thumbnail of Dynamics of Terminally Anchored Polymeric Chains

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Correction: An amplification-free, 16S rRNA test for Neisseria gonorrhoeae in urine

Sensors & Diagnostics

Correction for ‘An amplification-free, 16S rRNA test for Neisseria gonorrhoeae in urine’ by Zhenr... more Correction for ‘An amplification-free, 16S rRNA test for Neisseria gonorrhoeae in urine’ by Zhenrong Zheng et al., Sens. Diagn., 2023, 2, 163–167, https://doi.org/10.1039/d2sd00128d.

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Research paper thumbnail of Photocatalytic reduction of aromatic azides to amines using CdS and CdSe nanoparticles

Photochemical & Photobiological Sciences, 2004

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Research paper thumbnail of An amplification-free, 16S rRNA test for Neisseria gonorrhoeae in urine

Sensors & Diagnostics

Conductometric detection of N. gonorrhoeae 16S rRNA (green) by blockade of glass pores. Polystyre... more Conductometric detection of N. gonorrhoeae 16S rRNA (green) by blockade of glass pores. Polystyrene beads conjugated with PNA probe (orange) are charge neutral but acquire negative charge and electrophoretic mobility upon hybridization of rRNA.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Implantable aptamer–field-effect transistor neuroprobes for in vivo neurotransmitter monitoring

Science Advances, 2021

Implantable aptamer transistor probes for in vivo neurotransmitter monitoring advance brain activ... more Implantable aptamer transistor probes for in vivo neurotransmitter monitoring advance brain activity recording.

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Research paper thumbnail of Investigating Antibody Access to Adsorbed Protein Nanocapsule Interiors Using the Quartz Crystal Microbalance and Surface Plasmon Resonance

Vaults are nanoscale, ribonucleoprotein capsules (41 nm × 41 nm × 72.5 nm [1]) comprised primaril... more Vaults are nanoscale, ribonucleoprotein capsules (41 nm × 41 nm × 72.5 nm [1]) comprised primarily of 96 self-assembled copies of one 96 kDa protein, termed MVP (major vault protein). When deposited on polylysine-coated mica and imaged using cryoelectron microscopy, vaults appear to “open” into flower-like structures with eight rectangular ‘petals’ [2]. Upon closer examination, each ‘flower’ consists of a central ring with hooks that attach each petal to the center. The flowers are usually seen in pairs, suggesting that each whole vault is composed of two flowers, folded so that the ends of their petals touch. It is likely that vaults in cells open and close in response to cellular signals, reversibly encapsulating and releasing their contents. However, whether vaults open into flower-like structures in vivo is unknown.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Nucleic acid amplification-free detection of DNA and RNA at ultralow concentration

Current Opinion in Biotechnology, 2021

The broad spectrum of approaches for nucleic acid amplification-free detection of DNA and RNA at ... more The broad spectrum of approaches for nucleic acid amplification-free detection of DNA and RNA at single-digit attomolar (10-18 M) concentration and lower is reviewed. These low concentrations correspond roughly to the most clinically desirable detection range for pathogen-specific nucleic acid as well as the detection limits of commercially available, nucleic acid amplification tests based primarily on polymerase chain reaction (PCR). The need for more rapid and inexpensive, yet still highly accurate tests, has become evident during the pandemic. It is expected that publication of reports describing improved tests will accelerate soon, and this review covers the wide variety of detection methods based on both optical and electrical measurements that have been conceived over recent years, enabled generally by the advent of nanotechnology.

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