Ron Gill

University of Twente, Nanobiophyiscs, Faculty Member

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I am an interdisciplinary scientist who is passionate about translating and integrating knowledge from the basic sciences (Physics, Chemistry and Biology) to create novel advanced diagnostic solutions for Healthcare, Biotechnology and the Life Science sectors.

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PROF. OM PRAKASH SINHA

Amity University

David Seamon

Kansas State University

Petra Reinke

University of Virginia

Prof.Dr. İbrahim USLU

Gazi University

Kenneth Vecchio

University of California, San Diego

Khaled Dine

University of Dr moulay taher

Franz Giessibl

University of Regensburg

Jana Javornik

University of East London

Gwen Robbins Schug

University of North Carolina at Greensboro

Gabriel Gutierrez-Alonso

University of Salamanca

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Papers by Ron Gill

Localized surface plasmon resonance based sensing for pathogen detection

LSPR-Based Label Free Sensing in Absorbance Mode: Sensing of Therapeutic Antibodies in Serum>

Proceedings, Dec 4, 2017

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Spermine induced reversible collapse of deoxyribonucleic acid-bridged nanoparticle-based assemblies

Nano Research

DNA-linked 2D and 3D nano-assemblies find use in a diverse set of applications, ranging from DNA-... more DNA-linked 2D and 3D nano-assemblies find use in a diverse set of applications, ranging from DNA-origami in drug delivery and medical imaging, to DNA-linked nanoparticle structures for use in plasmonics and (bio)sensing. However, once these structures have been fully assembled, few options are available to modulate structure geometry. Here, we investigated the use of the polycation spermine to induce DNA collapse in small oligonucleotide-linked (54 bp) gold nanoparticle structures by monitoring shifts in the localized surface plasmon resonance (LSPR) peak and by comparing the data with finite-difference time-domain (FDTD) simulations. Our data shows that low concentrations of spermine can be applied to induce large changes in DNA conformation, leading to a significant reduction in interparticle distance (from ~ 25 to ~ 3 nm) and enhanced plasmonic coupling. The DNA collapse is near-instantaneous and reversible, and its application at low and high DNA densities is demonstrated with surface plasmon resonance imaging (SPRi), showing the potential of spermine to dynamically modulate distances and geometry in DNA-based nano-assemblies.

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Catalytic polynucleotide and its use for determination of analytes

Optical Detection of Analytes by Use of Semiconductor Nanoparticles

Selective lysis of cells

Selective Lysis of Cells

The contribution of capping layer dielectric properties to nanoparticle stability

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015

A surge in research aimed at both synthesis and application of colloidal nanoparticles occurred i... more A surge in research aimed at both synthesis and application of colloidal nanoparticles occurred in recent decades. Many biological and biomedical applications with nanoparticles depend on specifically tailored surface modifications that enable dispersion stability in high salt buffers. To address the impact of the coating layer on nanoparticles, we modify the venerable Derjaguin–Landau–Verwey–Overbeek (DLVO) theory that is typically used to explain colloidal stability. Our free energy functional includes the non-linear Poisson–Boltzmann potential and a modified van der Waals attraction that specifically considers a multi-layer geometry. Our results indicate that even a thin hydrocarbon layer over a gold nanoparticle core can substantially reduce particle–particle attraction. This modification can lead to nanoparticle stability over a wider range of salt concentrations, especially when the particle core radius and shell thickness are similar. Importantly, this effect depends on dielectric contrast and, therefore, cannot be explained by simply considering steric interactions. By comparing with experiments that assess the stability of nanoparticle dispersions, we show that this formulation can account for differences in nanoparticle stability due to various coating layer thicknesses.

Enhancing spectral shifts of plasmon-coupled noble metal nanoparticles for sensing applications

Phys. Chem. Chem. Phys., 2015

Enhancing spectral shifts for DNA sensing by heterogeneous plasmon coupling of Ag and Au nanopart... more

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Enhancing spectral shifts of plasmon-coupled noble metal nanoparticles for sensing applications

Noble metal nanoparticles possess very large scattering cross-sections, which make them useful as... more Noble metal nanoparticles possess very large scattering cross-sections, which make them useful as tags in biosensing assays with the potential to detect even single binding events. In this study, we investigated the effects of nanoparticle size on the shift in the light scattering spectrum following formation of Au-Au, Ag-Ag or Ag-Au dimers using FDTD simulations. We discuss the use of a color camera to detect these spectral changes for application in a target-induced dimerization sensing assay. Dimerization of Au nanoparticles induced a larger shift in color compared to Ag nanoparticles. Heterodimers composed of 60 nm Ag and 40 nm Au demonstrated an even larger spectral shift and color response compared to the best homodimer pair (80-40 nm Au). The increased spectral shift of the Ag-Au heterodimer was subsequently observed experimentally for the DNA-induced dimerization of nanoparticles, showing that careful selection of nanoparticle size and composition can significantly enhance recognition of nanoparticle dimerization events for use in (color) sensing assays.

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Toward efficient modification of large gold nanoparticles with DNA

Colloidal Nanoparticles For Biomedical Applications Ix, 2014

DNA-coated gold nanoparticles are one of the most researched nano-bio hybrid systems. Traditional... more DNA-coated gold nanoparticles are one of the most researched nano-bio hybrid systems. Traditionally their synthesis has been a long and tedious process, involving slow salt addition and long incubation steps. This stems from the fact that both DNA and gold particles are negatively charged, therefore efficient interaction is possible only at high salt concentration. However, unmodified particles are susceptible to aggregation at high salt concentrations. Most of the recent modification methods involve the use of surfactants or other small molecules to stabilize the nanoparticles against aggregation, enabling faster modification. Here we present our result on an alternative route to reach fast modification in low salt conditions, namely, reduction of the charge of DNA. We will discuss both the use of natural DNA under acidic pH conditions, and the use of DNA with a cationic, spermine-based "tail" which is commercially available under the name ZNA. Additionally we introduce a characterization method based on ensemble localized surface plasmon resonance measurement (LSPR) which enabled us to extract the kinetics of DNA absorbance without the need for fluorescent tags. Lastly we show that the same ZNA-based modification protocol can be effectively used for silver nanoparticle modification.

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Nanoparticle Aggregate-Based Fluorescence Enhancement for Highly Sensitive and Reproducible Detection of DNA

Particle & Particle Systems Characterization, 2014

ABSTRACT Sensitive detection of DNA at the sub picomolar range is demonstrated using a magnetic b... more ABSTRACT Sensitive detection of DNA at the sub picomolar range is demonstrated using a magnetic bead sandwich hybridization assay coupled with surface‐enhanced fluorescence (SEF)‐based amplification. Unlike enzymatic amplification, the SEF amplification step does not add any additional background to the measurement and does not cause a significant increase in the coefficient of variance (CV).

Probing Protein Kinase (CK2) and Alkaline Phosphatase with CdSe/ZnS Quantum Dots

Nano Letters, 2010

Semiconductor quantum dots (QDs) are used for the optical analysis of casein kinase (CK2) or the ... more Semiconductor quantum dots (QDs) are used for the optical analysis of casein kinase (CK2) or the hydrolytic activity of alkaline phosphatase (ALP). Two schemes for the analysis of CK2 by a FRET-based mechanism are described. One approach involves the CK2-catalyzed phosphorylation of a serine-containing peptide (1), linked to CdSe/ZnS QDs, with Atto-590-functionalized ATP. The second analytical method involves the specific association of the Atto-590-functionalized antibody to the phosphorylated product. The hydrolytic activity of ALP is followed by the application of phosphotyrosine (4)-modified CdSe/ZnS QDs in the presence of tyrosinase as a secondary reporter biocatalyst. The hydrolysis of (4) yields the tyrosine units that are oxidized by O(2)/tyrosinase to the respective dopaquinone product. The latter quinone units quench the QDs via an electron transfer route, leading to the optical detection of the ALP activity.

Fabrication of gold nano-particle arrays using two-dimensional templates from holographic lithography

Current Applied Physics, 2009

We report a simple and cost effective method to fabricate regular metallic particle arrays over l... more

Probing Kinase Activities by Electrochemistry, Contact-Angle Measurements, and Molecular-Force Interactions

Chemistry - A European Journal, 2008

Three different methods to investigate the activity of a protein kinase (casein kinase, CK2) are ... more Three different methods to investigate the activity of a protein kinase (casein kinase, CK2) are described. The phosphorylation of the sequence-specific peptide (1) by CK2 was monitored by electrochemical impedance spectroscopy (EIS). Phosphorylation of the peptide monolayer assembled on a Au electrode yields a negatively charged surface that electrostatically repels the negatively charged redox label [Fe(CN)6]3-/4-, thus increasing the interfacial electron-transfer resistance. The phosphorylation process by CK2 is further amplified by the association of the anti-phosphorylated peptide antibody to the monolayer. Binding of the antibody insulates the electrode surface, thus increasing the interfacial electron-transfer resistance in the presence of the redox label. This method enabled the quantitative analysis of the concentration of CK2 with a detection limit of ten units. The second method employed involved contact-angle measurements. Although the peptide 1-functionalized electrode revealed a contact angle of 67.5 degrees , phosphorylation of the peptide yielded a surface with enhanced hydrophilicity, 36.8 degrees. The biocatalyzed cleavage of the phosphate units with alkaline phosphatase regenerates the hydrophobic peptide monolayer, contact angle 55.3 degrees . The third method to characterize the CK2 system involved chemical force measurements between the phosphorylated peptide monolayer associated with the Au surface and a Au tip functionalized with the anti-phosphorylated peptide antibody. Although no significant rupture forces existed between the modified tip and the 1-functionalized surface (6+/-2 pN), significant rupture forces (multiples of 120+/-20 pN) were observed between the phosphorylated monolayer-modified surface and the antibody-functionalized tip. This rupture force is attributed to the dissociation of a simple binding event between the phosphorylated peptide and the fluorescent antibody (Fab) binding region.

Femtomolar DNA detection by parallel colorimetric darkfield microscopy of functionalized gold nanoparticles

Biosensors and Bioelectronics, 2011

We introduce a sensing platform for specific detection of DNA based on the formation of gold nano... more We introduce a sensing platform for specific detection of DNA based on the formation of gold nanoparticles dimers on a surface. The specific coupling of a second gold nanoparticle to a surface bound nanoparticle by DNA hybridization results in a red shift of the nanoparticle plasmon peak. This shift can be detected as a color change in the darkfield image of the gold nanoparticles. Parallel detection of hundreds of gold nanoparticles with a calibrated true color camera enabled us to detect specific binding of target DNA. This enables a limit of detection below 1.0 × 10 −14 M without the need for a spectrometer or a scanning stage.

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Femtomolar DNA detection by parallel colorimetric darkfield microscopy of functionalized gold nanoparticles

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Probing Kinase Activities by Electrochemistry, Contact‐Angle Measurements, and Molecular‐Force Interactions

Probing protein kinase (CK2) and alkaline phosphatase with CdSe/ZnS quantum dots

SERRS-based detection of dye-labeled DNA using positively-charged Ag nanoparticles

Analytical Methods, 2010

... Our results show that EDTA is more efficient than citrate, and this is &#x27;mirroring&am... more ... Our results show that EDTA is more efficient than citrate, and this is &#x27;mirroring&#x27; the fact that the tetra-amine was better than a tri-amine in the studies ... Atto 532 has a charge of −1 after conjugation to DNA, Bodipy 558 is a neutral dye, and Atto 565 is a dye with a charge of +1 after ...

Localized surface plasmon resonance based sensing for pathogen detection

LSPR-Based Label Free Sensing in Absorbance Mode: Sensing of Therapeutic Antibodies in Serum>

Proceedings, Dec 4, 2017

Download

Spermine induced reversible collapse of deoxyribonucleic acid-bridged nanoparticle-based assemblies

Nano Research

Download

Catalytic polynucleotide and its use for determination of analytes

Optical Detection of Analytes by Use of Semiconductor Nanoparticles

Selective lysis of cells

Selective Lysis of Cells

The contribution of capping layer dielectric properties to nanoparticle stability