Jon M Cooper

University of Glasgow, Glasgow, SCT, United Kingdom

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Publications (19)68.85 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: We demonstrate a single-step method for the generation of collagen and poly-l-Lysine (PLL) micropatterns on a poly(ethylene glycol) (PEG) functionalized glass surface for cell based assays. The method involves establishing a reliable silanization method to create an effective non-adhesive PEG layer on glass that inhibits cell attachment, followed by the spotting of collagen or PLL solutions using non-contact piezoelectric printing. We show for the first time that the spotted protein micropatterns remain stable on the PEG surface even after extensive washing, thus significantly simplifying protein pattern formation. We found that adherence and spreading of NIH-3T3 fibroblasts was confined to PLL and collagen areas of the micropatterns. In contrast, primary rat hepatocytes adhered and spread only on collagen micropatterns, where they formed uniform, well defined functionally active cell arrays. The differing affinity of hepatocytes and NIH-3T3 fibroblasts for collagen and PLL patterns was used to develop a simple technique for creating a co-culture of the two cell types. This has the potential to form structured arrays that mimic the in vivo hepatic environment and is easily integrated within a miniaturized analytical platform for developing high throughput toxicity analysis in vitro.
    Colloids and surfaces B: Biointerfaces 01/2012; 89:126-32. · 3.55 Impact Factor
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    ABSTRACT: The hydrodynamic interactions of micro-silica spheres trapped in a variety of networks using holographic optical tweezers are measured and characterized in terms of their predicted eigenmodes. The characteristic eigenmodes of the networks are distinguishable within 20-40 seconds of acquisition time. Three different multi-particle networks are considered; an eight-particle linear chain, a nine-particle square grid and, finally, an eight-particle ring. The eigenmodes and their decay rates are shown to behave as predicted by the Oseen tensor and the Langevin equation, respectively. Finally, we demonstrate the potential of using our micro-ring as a non-invasive sensor to the local environmental viscosity, by showing the distortion of the eigenmode spectrum due to the proximity of a planar boundary.
    Journal of Biophotonics 03/2010; 3(4):244-51. · 3.10 Impact Factor
  • Sakandar Rauf, Andrew Glidle, Jon M. Cooper
    Advanced Materials 06/2009; 21(40):4020 - 4024. · 14.83 Impact Factor
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    ABSTRACT: We describe the fabrication of a controllable microfluidic valve coupled with an electrochemical pump, which has been designed to deliver reagents to an integrated microfluidic biosensing system. Fluid, retained within an insertion reservoir using a stop valve, was pumped using electrochemical actuation, providing a low power, low voltage integrated Laboratory-on-a-Chip for reproducible, small volume fluidic manipulation. The properties of the valve were characterized using both X-ray photoelectron spectroscopy and contact angle measurements, enabling the calculation of the magnitude of the forces involved (which were subsequently verified through experimental measurement). Electrochemical generation of oxygen and hydrogen acted as an on-demand pressure system to force fluid over the stop valve barrier. The process of filling-up the biosensing chamber was characterized in terms of the time to fill, the energy used, and the peak power consumed. The potential of the device was illustrated using a glucose biosensor.
    Analytical Chemistry 02/2009; 81(4):1365-70. · 5.70 Impact Factor
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    ABSTRACT: The integration of a range of technologies including microfluidics, surface-enhanced Raman scattering and confocal microspectroscopy has been successfully used to characterize in situ single living CHO (Chinese hamster ovary) cells with a high degree of spatial (in three dimensions) and temporal (1 s per spectrum) resolution. Following the introduction of a continuous flow of ionomycin, the real time spectral response from the cell was monitored during the agonist-evoked Ca(2+) flux process. The methodology described has the potential to be used for the study of the cellular dynamics of a range of signalling processes.
    Analytical and Bioanalytical Chemistry 03/2008; 390(3):833-40. · 3.66 Impact Factor
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    ABSTRACT: A microfluidic format-based system has been developed for in situ monitoring of the calcium flux response to agonists using Chinese hamster ovary (CHO) cells. The assay is based on measuring the fluorescent intensity of the calcium-sensitive indicator, Fluo-4 AM, and was performed in a modified glass chip channel, whose surface was functionalised using a silanisation method with 3-aminopropyltriethoxysilane (APTS) (enabling the cells to be immobilised on the channel surface). CHO cells calcium flux response was measured for different agonists over a range of concentrations. Cells and reagents were introduced into the chip in a continuous flow as a series of plugs in a given sequence.
    Electrophoresis 01/2007; 27(24):5093-100. · 3.26 Impact Factor
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    ABSTRACT: A microfluidic based device has been developed for the continuous separation of polymer microspheres, taking advantage of the flow characteristics of systems. The chip consists of an asymmetric cavity with variable channel width which enables continuous amplification of the particle separation for different size particles within the laminar flow profile. The process has been examined by varying the sample inlet position, the sample to media flow rate ratio, and the total flow rate. This technique can be applied for manipulating both microscale biological and colloidal particles within microfluidic systems.
    Lab on a Chip 05/2006; 6(4):561-6. · 5.70 Impact Factor
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    ABSTRACT: A miniaturised lab-in-a-pill device has been produced incorporating a temperature and pH sensor with wireless communication using the 433.92 MHz ISM band. The device has been designed in order to enable real time in situ measurements in the gastrointestinal (GI) tract, and accordingly, issues concerning the resolution and accuracy of the data, and the lifetime of the device have been considered. The sensors, which will measure two key parameters reflecting the physiological environment in the GI (as indicators for disease) were both controlled by an application specific integrated circuit (ASIC). The data were sampled at 10-bit resolution prior to communication off chip as a single interleaved data stream. This incorporated a power saving serial bitstream data compression algorithm that was found to extend the service lifetime of the pill by 70%. An integrated on-off keying (OOK) radio transmitter was used to send the signal to a local receiver (base station), prior to acquisition on a computer. A permanent magnet was also incorporated in the device to enable non-visual tracking of the system. We report on the implementation of this device, together with an initial study sampling from within the porcine GI tract, showing that measurements from the lab-on-a-pill, in situ, was within 90% of literature values.
    Lab on a Chip 02/2006; 6(1):39-45. · 5.70 Impact Factor
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    ABSTRACT: We describe in situ neutron reflectivity (NR) and RAIRS studies of the chemical modification of films of a polypyrrole-based conducting polymer derived from the pentafluorophenyl ester of poly(pyrrole-N-propanoic acid) (PFP) electrodeposited on electrode surfaces. We explore the role of the solvent in controlling the rate of reaction with solution-based nucleophiles (amines, which react with the ester to form amides). By varying the identity of the solvent (water vs acetonitrile) and the neutron contrast (deuteration), we find that both the identity of the solvent and its population within the film are paramount in determining chemical reactivity and electroactivity. IR signatures allow monitoring of the reaction of solution-based amine-tagged species such as amino-terminated poly(propylene glycol), ferrocene ethylamine, and lysine with film-based ester functionalities: the carbonyl bands show ester/amide interconversion and some hydrolysis to acid. Time-dependent spectral analysis shows marked variations in reaction rate with (i) (co-)polymer composition (replacement of some fluorinated ester-functionalized pyrrole with unfunctionalized pyrrole), (ii) the solvent to which the polymer film is exposed, and (iii) the rate of polymer deposition. NR data provide solvent profiles as a function of distance perpendicular to the interface, the variations of which provide an explanation for film reactivity patterns. Homopolymer films are relatively hydrophobic, thus hindering reaction with species present in water solutions. Incorporating pyrrole groups raises the solvent population-dramatically for water-thereby facilitating entry and reaction of aqueous-based lysine. Changing film deposition rate yields films with different absolute levels of solvent and reactivity patterns that are dependent on the size of the reactant molecules: more rapid deposition of polymer gives films with a more open structure leading to a higher solvent content and thence increased reactivity. These results, supported by XPS and AFM data, allow assembly of composition-structure-reactivity correlations, in which the controlling feature is film solvation.
    The Journal of Physical Chemistry B 09/2005; 109(30):14335-43. · 3.61 Impact Factor
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    ABSTRACT: We use holographic optical tweezers to trap multiple micron-sized objects and manipulate them in 3-dimensions. Trapping multiple objects allow us to create 3-dimensional structures, examples of which include; simple cubes which can be rotated or scaled, complex crystal structures like the diamond lattice or interactive 3-dimensional control of trapped particles anywhere in the sample volume.
    Proc SPIE 01/2004;
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    ABSTRACT: We describe a method, based on X-ray photoelectron spectroscopy (XPS) measurements, to assess the extent of protein adsorption or binding on a variety of different muTAS and biosensor interfaces. Underpinning this method is the labeling of protein molecules with either iodine- or bromine-containing motifs by using protocols previously developed for radiotracer studies. Using this method, we have examined the adsorption and binding properties of a variety of modified electrodeposited polymer interfaces as well as other materials used in muTAS device fabrication. Using polymer interfaces modified with poly(propylene glycol) (PPG) chains, our results indicate that a chain of at least approximately 30 monomer units is required to inhibit nonspecific adsorption from concentrated protein solutions. The XPS methodology was also used to probe specific binding of avidins and enzyme conjugates thereof to biotinylated and mixed biotin/PPG-modified polymer interfaces. In one example, using competitive binding, it was established that the mode of binding of a peroxidase-streptavidin conjugate to a biotinylated modified polymer interface was primarily via the streptavidin moiety (as opposed to nonspecific binding via the enzyme conjugate). XPS evaluation of nonspecific and specific peroxidase-streptavidin immobilization on various functionalized polymers has guided the design and fabrication of functionalized interdigitated electrodes in a biosensing muTAS device. Subsequent characterization of this device using scanning electrochemical microscopy (SECM) corroborated the adsorption and binding previously inferred from XPS measurements on macroscale electrodes.
    Analytical Chemistry 07/2003; 75(11):2559-70. · 5.70 Impact Factor
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    ABSTRACT: Electropolymerized poly(o-toluidine) (PoT) films in the fully reduced state were studied using in situ neutron reflectivity. Acquisition of specular reflectivity profiles (as a function of neutron momentum transfer) for films exposed to perchloric acid solutions using H2O and D2O as solvents (‘contrast variation’) allowed extraction of structural information. In particular, it was possible to determine the polymer and solvent volume fractions within the film as functions of distance perpendicular to the interface. The data fit a single homogeneous layer model with a diffuse outer polymer ∣ solution interface. Within the interior of the film, the solvent volume fraction was small and varied with electrolyte composition. Film thickness increased monotonically with perchloric acid concentration: this was attributed to increased solvent content at low concentration and perchloric acid permeation at high concentration.
    Journal of Electroanalytical Chemistry. 01/2002;
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    ABSTRACT: Electropolymerized films of the functionalized pyrrole, pentafluorophenyl-3-(pyrrol-1-yl)propionate (PFP), were reacted with a solution-phase nucleophile, ferrocene ethylamine. This reaction was chosen as a model representative of a postdeposition modification of the polymer membrane's properties. For the first time, a nondestructive method for direct chemical analysis of the reaction profile within the electrodeposited polymer membrane after nucleophilic substitution is presented. This was achieved through the application of in situ neutron reflectivity with supplementary analytical information concerning the film's chemical composition obtained from XPS, FT-IR, and electrochemical measurements. The results presented illustrate how, for a partially reacted film resulting from a short reaction time, the extent of reaction with ferrocene ethylamine is not homogeneous throughout the thickness of the film, but occurs predominantly at the polymer/solution interface. We show that the progress of the reaction within the polymer film is limited by the transport of reacting species in the dense regions of the membrane that are furthest from the solution interface. The data do not fit an alternative model in which there is spatially homogeneous progression of the reaction front throughout the bulk of the thin film polymer. Guided by the neutron reflectivity measurements, suitable modifications were made to the electrodeposition method to prepare films whose architecture resulted in faster rates of reaction.
    10/2001;
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    ABSTRACT: Here we discuss the application of X-ray photoelectron spectroscopy and absorbance–reflectance FT-IR spectroscopy to establish and quantify reactivity relationships between a range of thiophene and pyrrole monomers. In particular we investigate the application of these techniques to the characterisation of conducting polymer materials grown potentiostatically from solutions containing a binary mixture of monomers. Our data have shown that XPS is especially effective in determining polymer composition and the linear correlation between this and solution composition has enabled prescriptive synthesis of copolymer materials from the different combinations of monomers described here. This technique is much more convenient and more reliable than elemental analysis. In contrast we show that FT-IR studies, whilst providing a useful qualitative guide to the functional group content of the material, do not facilitate detailed quantitative analysis because of large intrinsic errors.
    Journal of Materials Chemistry 01/2000; 10(8):1785-1793. · 5.97 Impact Factor
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    ABSTRACT: Here we describe the synthesis and electrochemical polymerisation of 2,5-di(2-thienyl)-3-(3-cyanopropyl)pyrrole, 2,5-di(2-thienyl)-3-(3-cyanopropyl)furan, and 3′-(3-cyanopropyl)-2,2′:5′,2″-terthiophene. We report a synthetic methodology to these important conducting polymer precursor compounds that is facile, convenient and flexible. The key precursor to this study is the functionalised diketone 1,4-bis(2-thienyl)-2-(3-cyanopropyl)butane-1,4-dione. This molecule undergoes convenient ring closure to the terthiophene and dithienylpyrrole and dithienylfuran derivatives, all of which are, to our knowledge, new compounds. Importantly, this approach provides a flexible route to a range of heterocyclic polymer precursors because the cyanoalkyl functionality is grafted to the diketone before ring closure. Subsequently the nitrile group provides synthetic utility either by reduction to the amine, or hydrolysis to the carboxylic acid. The new compounds described here undergo electrochemical polymerisation leading to fixed ratio copolymers of functionalised pyrrole, thiophene and furan with thiophene itself. We describe the characterisation of these polymers using FT-IR and X-ray photoelectron spectroscopies.
    Journal of Materials Chemistry 01/2000; 10(1):107-114. · 5.97 Impact Factor
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    ABSTRACT: The electrochemical polymerization of N-trimethylsilylethoxymethyl-3-methyl-4-pyrrole carboxylate ethyl ester (MPCE-SEM) in the presence of pyrrole, to give free-standing copolymer films is described. These films have been characterized by surface conductivity measurements, reflectance FTIR spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy. Increasing the relative concentration of MPCE-SEM in the polymerization solution resulted in an increase in the proportion of these units in the copolymer film. Increasing the proportion of MPCE-SEM units in the copolymer resulted in a decrease in surface conductivity. This is consistent with expectation because N-substituted polypyrroles tend to have lower conductivity values than unsubstituted polypyrrole. Significantly, it has also been shown that the N-protecting group of the MPCE-SEM unit can be removed after polymerization under mild conditions in a solid phase deprotection procedure. © 1998 Society of Chemical Industry
    Polymer International 03/1999; 47(1):43 - 49. · 2.13 Impact Factor
  • Polymer International - POLYM INT. 01/1998; 47(1):43-49.
  • Jon. M. Cooper, David G. Morris, Karl S. Ryder
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    ABSTRACT: We describe for the first time direct electronic communication between a functionalised, conducting poly(pyrrcle) and a redox protein (cytochrome c) in solution, demonstrating that facile, heterogeneous electron transfer is a function both of polymer substituent pattern and backbone conductivity.
    Journal of the Chemical Society Chemical Communications 01/1995;
  • Karl S. Ryder, David G. Morris, Jon M. Cooper
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    ABSTRACT: The synthesis and characterisation of novel β-substituted poly(pyrroles) derived from poly(I)(I= pentafluorophenyl 1H-pyrrole-3-acetate) and reactions of electrode-bound poly(I) with a variety of neutral nucleophiles, including 1,2,3,4-tetra-O-acetyl-β-D-glucopyranose are described.
    Journal of the Chemical Society Chemical Communications 01/1995;

Publication Stats

120 Citations
78 Downloads
683 Views
68.85 Total Impact Points

Institutions

  • 1999–2009
    • University of Glasgow
      • Division of Electronics and Electrical Engineering
      Glasgow, SCT, United Kingdom
  • 2006–2008
    • University of Hull
      • Department of Chemistry
      Hull, ENG, United Kingdom