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Spiers ME, Nielsen DJ, Pavey KD, Truong YB, Rutledge GC, Kingshott P, Eldridge DS. Conductive, Acid-Doped Polyaniline Electrospun Nanofiber Gas Sensing Substrates Made Using a Facile Dissolution Method. ACS Appl Mater Interfaces 2021; 13:52950-52959. [PMID: 34723480 DOI: 10.1021/acsami.1c08136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A novel dissolution method that allows for the total solvation of high-concentration, high-molecular-weight polyaniline (PANi) doped with (+)-camphor-10-sulfonic acid (CSA) is reported. Preparation of 12-16 wt % 65,000 Da PANi solutions in N,N-dimethylformamide is achievable using a simple one-pot method. Doped polyaniline solutions in common organic solvents were processed into nanofibers using a convenient single-nozzle electrospinning technique. The electrospinning of PANi-CSA into nanofibrous membranes generated substrates that were subsequently employed in colorimetric gas sensing. These substrates demonstrated linearity of response upon exposure to 50-5500 ppm ammonia at ambient (50 ± 10% RH) and high (80% RH) humidity.
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Affiliation(s)
| | - David J Nielsen
- Defence Science and Technology Group, Fishermans Bend 3207, Australia
| | - Karl D Pavey
- Defence Science and Technology Group, Fishermans Bend 3207, Australia
| | - Yen B Truong
- Commonwealth Science and Industry Research Organization, Clayton 3168, Australia
| | - Gregory C Rutledge
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Peter Kingshott
- Swinburne University of Technology, Hawthorn 3122, Australia
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Boyson TK, Dagdigian PJ, Pavey KD, FitzGerald NJ, Spence TG, Moore DS, Harb CC. Real-time multiplexed digital cavity-enhanced spectroscopy. Opt Lett 2015; 40:4560-4562. [PMID: 26421581 DOI: 10.1364/ol.40.004560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Cavity-enhanced spectroscopy is a sensitive optical absorption technique but one where the practical applications have been limited to studying small wavelength ranges. This Letter shows that wideband operation can be achieved by combining techniques usually reserved for the communications community with that of cavity-enhanced spectroscopy, producing a multiplexed real-time cavity-enhanced spectrometer. We use multiple collinear laser sources operating asynchronously and simultaneously while being detected on a single photodetector. This is synonymous with radio frequency (RF) cellular systems in which signals are detected on a single antenna but decoded uniquely. Here, we demonstrate results with spectra of methyl salicylate and show parts-per-billion per root hertz sensitivity measured in real-time.
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Affiliation(s)
- Mijan Miah
- a School of Pharmacy and Biomolecular Sciences , University of Brighton , BNGJ, 2 4, Brighton, UK
| | - Karl D. Pavey
- a School of Pharmacy and Biomolecular Sciences , University of Brighton , BNGJ, 2 4, Brighton, UK
| | - Vladimir M. Gun'ko
- b Institute of Surface Chemistry , 17 General Naumov Street, 03164, Kiev, Ukraine
| | - Rosemary Sheehan
- a School of Pharmacy and Biomolecular Sciences , University of Brighton , BNGJ, 2 4, Brighton, UK
| | - Peter J. Cragg
- a School of Pharmacy and Biomolecular Sciences , University of Brighton , BNGJ, 2 4, Brighton, UK
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Fucassi F, Lowe JE, Pavey KD, Shah S, Faragher RGA, Green MHL, Paul F, O'Hare D, Cragg PJ. α-Lipoic acid and glutathione protect against the prooxidant activity of SOD/catalase mimetic manganese salen derivatives. J Inorg Biochem 2007; 101:225-32. [PMID: 17095093 DOI: 10.1016/j.jinorgbio.2006.09.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 09/05/2006] [Accepted: 09/15/2006] [Indexed: 01/02/2023]
Abstract
Manganese(III) N,N'-ethylenebis(salicylideneiminato) chloride (Mn-salen chloride) and manganese(III) N,N'-ethylenebis(3-methoxysalicylideneiminato) chloride (Mn-(3,3'-MeO)salen chloride) are in vitro superoxide dismutase and catalase mimetics. They protect against free radical-related disease in animals, but Mn-salen can also be a potent prooxidant, damaging free DNA. Mn-salen protects human fibroblast DNA against hydrogen peroxide damage, however, damage to free DNA was confirmed by the comet assay. The DNA-damaging activity was dramatically reduced by co-administration with glutathione with the combination being less damaging to free DNA than either molecule alone. alpha-Lipoic acid, an antioxidant disulfide commonly used as a dietary supplement, also prevented Mn-salen prooxidant activity. Mn-(3,3'-MeO)salen protected fibroblasts against hydrogen peroxide as efficiently as Mn-salen and showed little damaging activity against free DNA. Protection was invested by both complexes in the presence and in the absence of EDTA, a potential competing chelator. Stabilities of the complexes with respect to decomposition and inactivation were studied by spectroscopic and electrochemical techniques. The complexes' binding to, and cleavage of, DNA was measured using a quartz crystal resonant sensor. Mn-salen was shown to bind strongly to DNA, prior to cleaving it; Mn-(3,3'-MeO)salen bound weakly and left DNA intact. Co-administration of either glutathione or alpha-lipoic acid appears to inhibit binding by Mn-salen thus preventing DNA-cleavage.
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Affiliation(s)
- Flavia Fucassi
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Cockcroft Building, Lewes Road, Moulsecoomb, Brighton BN2 4GJ, UK
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Pavey KD, Hunter AC, Paul F. Real-time evaluation of macromolecular surface modified quartz crystal resonant sensors under cryogenic stress for biological applications. Biosens Bioelectron 2003; 18:1349-54. [PMID: 12896835 DOI: 10.1016/s0956-5663(03)00062-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This study presents a novel auto-gain-control based quartz acoustic sensor technology capable of constant quartz crystal operation when cycled between ambient (22 degrees C) and cryogenic temperatures (-196 degrees C), afforded by direct exposure of crystals to bulk liquid nitrogen. The real-time frequency response profiles due to freeze-thaw cycling on crystals of differing surface finish and two model macromolecular surface coatings were studied in order to determine surface events such as water uptake. The quartz crystal surface finishes used were optically polished or lapped to one of two surface finishes. These were used as control native gold electrodes, and these surfaces were further coated with bovine serum albumin or the tri-block copolymer, poloxamer-188 as model macromolecular surface architectures. Crystals were snap frozen in liquid nitrogen and allowed to return to ambient temperature under controlled conditions. The processes of ice formation, thawing and evaporation were followed in real-time and comparisons were made between the test samples in order to assess the capability of this technique for sensing changes in surface characteristics such as the entrapment of water.
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Affiliation(s)
- Karl D Pavey
- Acoustic Sensors Research Group, School of Pharmacy and Biomolecular Sciences, Cockcroft Building, University of Brighton, Lewes Road, Brighton, East Sussex BN2 4GJ, UK.
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Abstract
Acoustic sensor technologies have a long and prestigious history. However, liquid phase applications based upon thickness shear mode transducers are a relatively recent addition but are nonetheless being rapidly accepted as a broad usage analytical platform upon which to carry out label-free, real-time chemical, biological and pharmaceutical assays. This article discusses the development of thickness shear mode devices, current technologies, with a focus on the breadth of application and the future potential of the technique within the pharmaceutical and biochemical industries.
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Affiliation(s)
- Karl D Pavey
- School of Pharmacy and Biomolecular Sciences, Cockroft Building, University of Brighton, Moulsecoombe, Brighton, UK.
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Langford J, Pavey KD, Olliff CJ, Cragg PJ, Hanlon GW, Paul F, Rees GD. Real-time monitoring of stain formation and removal on calcium hydroxyapatite surfaces using quartz crystal sensor technology. Analyst 2002; 127:360-7. [PMID: 11996360 DOI: 10.1039/b109684m] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Stain formation, stain inhibition and stain removal may be monitored in real-time using a novel method employing a quartz crystal resonance sensor (QCR), based upon quartz crystal microbalance (QCM) technologies. Crystalline hydroxyapatite (HA) surfaces were prepared on phosphate-terminated, polymer-modified gold surfaces of quartz crystal transducers. The resulting sensors were placed in a specially constructed flow cell, and the interaction of adsorbates from the tea stain solution monitored as a function of time. The ability of sodium tripolyphosphate (STP) to remove extrinsic stain and also to inhibit its formation was examined. The adsorption of material from the staining solution passed over the sensor was clearly observable, and once bound, the crystal based real-time data suggest that tea adsorbates were not removed in the absence of an active under conditions of continuous flow. STP was shown to rapidly remove existing stain, and exhibited a clear inhibitory action on stain formation irrespective of whether the HA had been previously exposed to tea chromogens. The continuous data generated by the QCR technique were in good agreement with the results obtained using a discontinuous spectrophotometric method. The presently described quartz crystal model for extrinsic dental stain should provide a valuable tool to aid understanding of the interactions of staining agents with a crystalline HA surface as a model tooth surface, and to evaluate the efficacy and mode of action of STP and putative stain removal agents.
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Affiliation(s)
- J Langford
- School of Pharmacy and Biomolecular Sciences, University of Brighton, UK
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Pavey KD, Barnes LM, Hanlon GW, Olliff CJ, Ali Z, Paul F. A rapid, non-destructive method for the determination of Staphylococcus epidermidis adhesion to surfaces using quartz crystal resonant sensor technology. Lett Appl Microbiol 2001; 33:344-8. [PMID: 11696093 DOI: 10.1046/j.1472-765x.2001.01009.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To investigate the use of quartz crystal resonant sensor (QCRS) technology to determine the adhesion of Staphylococcus epidermidis to fibronectin-coated surfaces. METHODS AND RESULTS QCRS sensors (14 MHz) with 4 mm gold electrodes were coated with fibronectin and exposed for 15 min to suspensions of Staph. epidermidis ranging in concentration from 1 x 10(2) to 1 x 10(6) cfu ml(-1). Changes in resonant frequency were recorded and showed a linear relationship with the logarithm of cell concentration over the range tested. CONCLUSIONS QCRS technology was shown to be a rapid, sensitive and non-destructive method for measuring the adhesion of bacteria to surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY This report demonstrates that QCRS technology has the potential to be used for a range of applications requiring measurement of bacteria on surfaces. In particular, it may be used for the real-time monitoring of bacterial biofilm formation.
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Affiliation(s)
- K D Pavey
- School of Pharmacy and Biomolecular Sciences, Cockcroft Building, University of Brighton, Lewes Road, Brighton, BN2 4GJ, UK.
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Pavey KD, Miah M, Fucassi F, Paul F, Cragg PJ. Vitamin C induced decomposition of lipid hydroperoxides: direct evidence of genotoxin-DNA binding detected by QCRS. Chem Commun (Camb) 2001:1886-7. [PMID: 12240363 DOI: 10.1039/b105766a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report direct evidence for human DNA-binding to precursors of mutagenic lesion-inducing compounds, produced form the vitamin C induced decomposition of lipid hydroperoxides, using a quartz crystal resonant sensor assay.
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Affiliation(s)
- K D Pavey
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Lewes Road, Brighton, UK BN2 4GJ.
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Abstract
Human serum albumin (HSA) was immobilised on the gold surface of a quartz crystal resonance sensor (QCRS) and exposed to warfarin and diazepam. Distinct decreases in frequency of differing magnitudes were observed upon exposure of the protein to each of the compounds suggesting strongly that a ligand interaction was occurring. Moreover, as sequential exposure in any order was observed to yield distinct repeatable frequency decreases for the ligands indicated, screening for site specific binding may be possible. Identically immobilised bovine serum albumin (BSA) gave no response to either compound.
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Affiliation(s)
- K D Pavey
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Lewes Road, Brighton, East Sussex, UK BN2 4GJ
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Fucassi F, Pavey KD, Lowe JE, Olliff CJ, Green MHL, Cragg PJ, Paul F. Characterisation of small molecule binding to DNA using a quartz crystal resonant sensor. Chem Commun (Camb) 2001. [DOI: 10.1039/b100175m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Pavey KD, Ali Z, Olliff CJ, Paul F. Application of the quartz crystal microbalance to the monitoring of Staphylococcus epidermidis antigen-antibody agglutination. J Pharm Biomed Anal 1999; 20:241-5. [PMID: 10704028 DOI: 10.1016/s0731-7085(99)00026-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The change in solution properties due to the agglutination of an antigen with its specific antibody has previously been used as a marker of infection. This method has been modified to allow the binding activity between species to be followed using the frequency response of a quartz crystal microbalance (QCM). The Bayston agglutination plate assay for Staphylococcus epidermidis has been modified to allow the electrode of a QCM to act as a direct sensor for the change in solution properties as agglutination occurs. Antibody and antigen were introduced to the crystal surface and the agglutination process was followed as a change in crystal resonant frequency. Serum, known to be infected with the organism, gave a titre of 3.9x10(-2)% v/v (-118 Hz, +/-12 SD, N = 9) matching that given by triplicate plate assay. Uninfected serum gave no frequency changes at this concentration, yielding a titre of 2.5x10(-2)% v/v again matching the plate titre (N = 3). Infected serum gave responses 40 times faster then those of the uninfected serum. The piezoelectric quartz crystal method gave a positive or negative diagnosis in <15 min compared with the 24 h required for the plate assay.
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Affiliation(s)
- K D Pavey
- Novel Methods Group, CASS, Smithkline Beecham Pharmaceuticals, Harlow, Essex, UK.
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Pavey KD, Olliff CJ. SPR analysis of the total reduction of protein adsorption to surfaces coated with mixtures of long- and short-chain polyethylene oxide block copolymers. Biomaterials 1999; 20:885-90. [PMID: 10226714 DOI: 10.1016/s0142-9612(98)00245-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PEO/PPO/PEO triblock copolymers have previously been shown to reduce the binding of proteins to a variety of surfaces. In this study, mixtures of long- and short-chain copolymers have been shown to adhere to gold substrate surface plasmon resonance slides. The mixtures have been shown to significantly reduce the binding of BSA to gold surfaces, compared to the more commonly used long chain PEO copolymers. These mixtures have been shown to be more effective, than either short, or long-chain copolymers used individually, complementing a published theoretical treatise of PEO surfactant behaviour towards protein interaction with surfaces.
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Affiliation(s)
- K D Pavey
- Novel Methods Group, CASS, SmithKline Beecham Pharmaceuticals, Harlow, Essex, UK.
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Pavey KD, Paul F, Olliff CJ, Jim Baker T. Synthesis and characterisation of N-(3-dihydroxyborylphenyl)-5-mercaptopentanamide: a novel self-assembling vicinal diol receptor. Chem Commun (Camb) 1999. [DOI: 10.1039/a906542c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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