Gary Kinsel | Southern Illinois University at Carbondale (original) (raw)

Papers by Gary Kinsel

MALDI MS of Proteins Adsorbed to Modified and Unmodified Polymer Substrates

MALDI Mass Spectrometric Probes of Biomolecule Adsorption to Pulsed RF Plasma Modified Surfaces

Influence of Sample Preparation and Surface-Protein Interactions on Analyte Ionization by MALDI

MALDI MS as a Method for Studying Surface-Protein Interactions

Arginine/2,5-Dihydroxybenzoic Acid Clusters: An Experimental and Computational Study of the Gas-Phase and Solid-State Systems †

The Journal of Physical Chemistry A, 2004

The 1:1 adduct of arginine with 2,5-dihydroxybenzoic acid (DHB) has been studied in the gas phase... more The 1:1 adduct of arginine with 2,5-dihydroxybenzoic acid (DHB) has been studied in the gas phase and in the solid state. Experimentally, the ionization energy (IE) of the 1:1 cluster was determined by wavelength-dependent laser ionization of clusters formed by seeding DHB ...

Langmuir, 2010

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is used for the first time ... more Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is used for the first time to characterize radio frequency plasma-deposited polymers and for investigation of the plasma polymerization process. The MALDI mass spectra of the plasma polymers of allyl alcohol, di(ethylene glycol) vinyl ether and ethylene glycol butyl vinyl ether are all reported using solvent-based MALDI sample preparation approaches. The MALDI mass spectra of each of the three plasma polymers contain distinctive polymer series ion signals having molecular weight distributions below 2000 Da. Unexpectedly, however, the ion signals from each of the three plasma polymers show a common polymer repeat unit of 44 Da, for which the chemical formula is most likely -(C 2 H 4 O)-, and no evidence of the expected radical chain polymerization polymer is detected. These results are discussed in terms of the likely involvement of gas-phase radical species having different stabilities in the radio frequency plasma environment.

Langmuir, 2013

A Cationic polymer nanobrush was synthesized, attached to a MALDI target and used for the fractio... more A Cationic polymer nanobrush was synthesized, attached to a MALDI target and used for the fractionation of peptides and proteins based on their pI, prior to analysis by MALDI-MS. The cationic polymer nanobrush was synthesized on a gold substrate by AIBN photo-initiated polymerization, using a 30:70 ratio of 2-aminoethyl-methacrylate hydrochloride (AEMA) : Nisopropylacrylamide (NIPAAM). This brush showed selectivity for adsorption of acidic peptides and proteins, and allowed fractionation of simple two-component mixtures to be completed in less than 10 minutes. The brush-adsorbed biomolecules were recovered by treating the nanobrush with ammonium hydroxide, which effectively collapsed the brush thereby releasing the trapped compounds for MALDI MS analysis. These results demonstrate that nanobrush can serve as a convenient platform for rapid fractionation of biomolecules prior to analysis by MALDI-MS.

Journal of the American Society for Mass Spectrometry, 2000

Polymer surface-peptide binding interactions have been shown previously to lead to reductions in ... more Polymer surface-peptide binding interactions have been shown previously to lead to reductions in peptide matrix assisted laser desorption/ionization (MALDI) ion signals. In previous studies, increases in surface-peptide binding were characterized by the increases in both the initially adsorbed and retained quantities of 125 I-radiolabeled peptides. The present studies establish a specific correlation between the peptide retention properties of the polymer surface and the reduction in the peptide MALDI ion signal. This correlation is demonstrated by obtaining MALDI mass spectra of angiotensin I applied to various polymer surfaces having a range of peptide adsorption and retention properties. In addition, the use of a MALDI based method of standard additions is shown to allow the quantitation of the polymer surfacepeptide retention affinity for angiotensin I and porcine insulin. The MALDI standard additions method for measurement of surface-peptide retention affinities offers a number of significant advantages over conventional radiolabeled peptide binding methods and promises to be a valuable tool for the determination of this important biomaterial characteristic.

First-Generation Chiral Metallodendrimers: Stereoselective Synthesis of Rigid D 3 -Symmetric Tetranuclear Ruthenium Complexes

Journal of the American Chemical Society, 1997

A less-explored but equally exciting aspect of these metallodendrimers concerns the stereochemist... more A less-explored but equally exciting aspect of these metallodendrimers concerns the stereochemistry of these supramolecules. Metallodendrimers constructed of D 3 -symmetric [M(diimine) 3 ] 2+ units 10 - 25 exhibit tremendous stereochemical complexity arising from the local chirality ...

Influence of sample preparation methodology on the reduction of peptide matrix-assisted laser desorption/ionization ion signals by surface-peptide binding

Journal of Mass Spectrometry, 1999

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Instrumentation Science & Technology, 1998

Biomaterials, 2004

Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) has been used for over a... more Matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) has been used for over a decade for the determination of purity and accurate molecular masses of macromolecular analytes, such as proteins, in solution. In the last few years the technique has been adapted to become a new surface analysis method with unique capabilities that complement established biomaterial surface analysis methods such as XPS and ToF-SSIMS. These new MALDI variant methods, which we shall collectively summarize as Surface-MALDI-MS, are capable of desorbing adsorbed macromolecules from biomaterial surfaces and detecting their molecular ions with high mass resolution and at levels much below monolayer coverage. Thus, Surface-MALDI-MS offers unique means of addressing biomaterial surface analysis needs, such as identification of the proteins and lipids that adsorb from multicomponent biological solutions in vitro and in vivo, the study of interactions between biomaterial surfaces and biomolecules, and identification of surface-enriched additives and contaminants. Surface-MALDI-MS is rapid, experimentally convenient, overcomes limitations in mass resolution and sensitivity of established biochemical techniques such as SDS-PAGE, and can in some circumstances be used for the quantitative analysis of adsorbed protein amounts. At this early stage of development, however, limitations exist: in some cases proteins are not detectable, which appears to be related to tight surface binding. This review summarizes ways in which Surface-MALDI-MS methods have been applied to the study of a range of issues in biomaterials surfaces research.

Analytical Chemistry, 1999

The influence of polymer surface-protein binding affinity on protein ion signals in matrix-assist... more The influence of polymer surface-protein binding affinity on protein ion signals in matrix-assisted laser desorption/ ionization (MALDI) mass spectrometry is examined. The surfaces of poly(vinylidene fluoride) and poly(ethylene terephthalate) polymer substrates are modified by pulsed rf plasma deposition of allylamine. By varying the on/off duty cycle of the pulsed rf plasma, the polymer substrate surfaces are coated with thin films having varying densities of surface amine groups. The varying surface amine density is shown to lead to systematic changes in the surface binding affinity for the 125 I-radiolabeled peptides angiotensin I and porcine insulin. Unlabeled angiotensin I and porcine insulin are then deposited on the pulsed rf plasma-modified substrates and analyzed by MALDI mass spectrometry. The experimental approach involves applying the peptide to the modified polymer surface in an aqueous phosphate-buffered saline solution and allowing the peptide solution to dry completely under ambient conditions. Subsequently, the MALDI matrix r-cyano-4hydroxycinnamic acid in methanol and 10% trifluoroacetic acid in water are added to the peptide-coated modified polymer surfaces. The results of these studies demonstrate that, for the sample preparation method employed, increases in the surface peptide binding affinity lead to decreases in the peptide MALDI ion signal.

Analytical Biochemistry, 1999

Previous studies have shown that increases in surface-peptide binding affinity result in decrease... more Previous studies have shown that increases in surface-peptide binding affinity result in decreases in peptide matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) ion signals. The present work demonstrates that, with appropriate corrections for peptide ionization efficiency under MALDI conditions, relative surface-peptide binding affinities can be assayed using the MALDI MS methodology. Peptides with a range of pI values are allowed to interact with amine-modified and carboxylic acidmodified polymer surfaces (produced by pulsed radiofrequency plasma polymerization of allyl amine and vinyl acetic acid) in buffered solutions of neutral pH. Because of the net positive and negative charges associated with the peptides and surfaces in solution, both electrostatic and hydrophilic interactions play a role in the surface-peptide interaction. Consistent with expectations, the peptide MALDI ion signals for peptides with net negative charges in solution are smaller than those for peptides with net positive charges in solution when the peptides are allowed to interact with positively charged surfaces. A reversal of the relative peptide MALDI ion signal intensities is observed when the same peptides are allowed to interact with negatively charged surfaces. Cumulatively, the results demonstrate that even modest changes in surfacepeptide interactions can be comparatively probed by MALDI mass spectrometry.

Analytical Biochemistry, 2010

Analytical Chemistry, 2007

Scientific Reports

Fabrication of inexpensive and flexible electronic and electrochemical sensors is in high demand ... more Fabrication of inexpensive and flexible electronic and electrochemical sensors is in high demand for a wide range of biochemical and biomedical applications. We explore hand fabrication of CNt modified AgNPs electrodes using wax-on-plastic platforms and their application in electrochemical immunosensing. Wax patterns were printed on polyethylene terephthalate-based substrates to laydown templates for the electrodes. Hand painting was employed to fabricate a silver conductive layer using AgNps ink applied in the hydrophilic regions of the substrate surrounded by wax. CNt was drop cast on top of the working electrodes to improve their electrochemical signal. the device layers were characterized by scanning electron microscopy. the electrochemical performance of the hand fabricated AgNPs and CNT/AgNPs electrodes was tested using cyclic voltammetry, differential pulse voltammetry, and amperometry. the electrochemical response of CNt/AgNps electrodes was relatively faster, higher, and more selective than unmodified AgNPs sensing electrodes. Finally, the hand-painted CNt/AgNps electrodes were applied to detect carcinoembryonic antigen (CeA) by measuring the endproduct of immunoassay performed on magnetic particles. the detection limit for CeA was found to be 0.46 ng/mL. Chemical and bio(chemical) sensing on chips integrated with diverse detection tools are currently hot areas of research 1. Reports are growing rapidly on the development of novel procedures to fabricate sensor chips and microfluidic platforms 2-4. Therefore, integration of electronic/electrochemical sensors into flexible devices are in high demand mainly as geared toward point-of-care and wearable sensors 5,6. For almost a decade, printing methods (i.e. screen, wax, and inkjet) have drawn the attention of the biosensing community as a means to develop inexpensive and simple fabrication procedures 7-18. Screen-printing has been popular for electrochemical biosensing because it produces reliable electrode surfaces owing to large metal particulates in the ink 19,20. However, screen-printing requires delicate and thin screens that are tedious to manufacture. Inkjet printing of metallic ink has been widely used for high throughput, instantaneous patterning but it is sensitive to the rheological properties of ink and prone to frequent nozzle clogging 21,22. These potential problems might be costly in resource deprived settings. Wax printing has emerged as a means to fabricate robust hydrophobic patterns for electrochemical devices on paper substrates 23-25. Although paper substrates are inexpensive they lack tear toughness that might be required under certain environmental conditions. Here, we introduce a simpler method of fabrication that combines wax patterning, hand-painting, and drop casting to fabricate sensitive electrochemical sensors on a plastic substrate. Plastic substrates are as inexpensive as paper-based substrates (i.e. $0.50 per letter-sized sheet), but they have high tear toughness which is critical for greater shelf-life. The fabrication strategy used here can be used to construct a variety of electrodes using various materials by avoiding the problems of inkjet printing and screen-printing while maintaining low-cost and robust response. In contrast to paper-based fabrication, wax patterns on plastic substrates do not require heating to create stable hydrophobic barriers between hydrophilic islands 26. Such thermal stability can benefit fabrication procedures where high temperatures are involved in subsequent steps.

Journal of Mass Spectrometry, 2015

Matrix-assisted laser desorption/ionization (MALDI) ion formation mechanisms were investigated by... more Matrix-assisted laser desorption/ionization (MALDI) ion formation mechanisms were investigated by comparison of isomers of dihydroxybenzoic acid. These exhibit substantially different MALDI performance, the basis for which was not previously understood. Luminescence decay curves are used here to estimate excited electronic state properties relevant for the Coupled Chemical and Physical Dynamics (CPCD) model. With these estimates, the CPCD predictions for relative total ion and analyte ion yields are in good agreement with the data for the DHB isomers. Predictions of a thermal equilibrium model were also compared and found to be incompatible with the data.

$Research paper thumbnail of Method for fractioning peptides and other compounds$

Method for fractioning peptides and other compounds

Non-Fouling Surfaces for Enhanced Performance MALDI Targets

Non-fouling surfaces designed to resist adsorption of proteins have been extensively investigated... more Non-fouling surfaces designed to resist adsorption of proteins have been extensively investigated by a large number of researchers in the biomaterials field. Previous studies in our group have shown that protein analyte signals in Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) experiments are strongly influenced by the binding interactions between the target surface and protein. Specifically, the protein signal increases with decreasing surface-protein binding affinity, most likely as a result of unbound protein being more efficiently incorporated into the MALDI matrix for subsequent desorption and ionization. Thus, surface modification of the MALDI target to reduce the protein adsorption should result in lowered protein limits of detection (LODs). The studies described investigate the influence of a number of approaches to produce non-fouling MALDI target surfaces on the protein analyte ion signal. In general, the non-fouling MALDI target was produced by c...