Skip to main content

Zeljka Krpetic

University College Dublin, School of Chemistry and Chemical Biology, Post-Doc

Followers

38

Following

16

Co-authors

15

Public Views

Address: Dún Laoghaire, Dublin, Ireland

less

Rosario Núñez

francesc teixidor

Xavier Fontrodona

Loughborough University

Wolfgang Milius

University Of Bayreuth, Germany

Interests

Uploads

Papers by Zeljka Krpetic

A multidentate peptide for stabilization and facile bioconjugation of gold nanoparticles

by Francesca Porta and Zeljka Krpetic

Gold nanoparticles of two different sizes stabilized by a 15-mer peptide ligand specifically desi... more Gold nanoparticles of two different sizes stabilized by a 15-mer peptide ligand specifically designed for this purpose have been prepared in aqueous solution and characterized by UV-vis spectroscopy and TEM. The presence of the ligand and its binding mode to the particles via its four cystein thiols is evidenced by FTIR and NMR spectroscopy. Biotinylation of the particles via binding to a freely accessible lysine residue is demonstrated.

Preparation and Characterisation of Au Nanoparticles Capped with Mercaptocarboranyl Clusters

Dalton Transactions

11 SI Integrative Biol

17 Conjugation of PEG and gold nanoparticles to increase the accessibility and valency of tethered RNA splicing enhancers SI

Electroreductions on Silver-Based Electrocatalysts: The Use of Ag Nanoparticles for CHCl 3 to CH 4 Conversion

Fuel Cells, 2009

A preliminary investigation on a new class on electrocatalytic materials for the electroreduction... more A preliminary investigation on a new class on electrocatalytic materials for the electroreduction of organic halides is presented and discussed. The electrocatalysts are based on silver nanoparticles (Ag_NP), ad hoc synthesised by chemical reduction of an aqueous silver salt in the presence of six different stabilising agents. The colloids are then supported on carbon powder (10% loading) for further characterisation and use. The electrocatalytic properties of the Ag_NP/carbon composites towards the dehalogenation of halocompounds are tested by cyclic voltammetry and by preparative electrolysis. The hydrodehalogenation of trichloromethane, extensively studied by this group, is selected as a model reaction, because of its relevance for the detoxification of wastes. The voltammetric characterisation is performed in an aqueous solution, supporting the composites on cavity microelectrodes. Gas-diffusion electrodes (GDE) based on the most promising Ag_NP composite -and, for reference, on a commercial Ag/C oxygen reduction electrocatalystare then tested in an electrolytic process for the progressive conversion of gaseous trichloromethane to less chlorinated compounds, and ultimately to methane.

Mapping protein binding sites on the biomolecular corona of nanoparticles

Nature Nanotechnology, 2015

Nanoparticles in a biological milieu are known to form a sufficiently long-lived and well-organiz... more Nanoparticles in a biological milieu are known to form a sufficiently long-lived and well-organized &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;corona&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; of biomolecules to confer a biological identity to the particle. Because this nanoparticle-biomolecule complex interacts with cells and biological barriers, potentially engaging with different biological pathways, it is important to clarify the presentation of functional biomolecular motifs at its interface. Here, we demonstrate that by using antibody-labelled gold nanoparticles, differential centrifugal sedimentation and various imaging techniques it is possible to identify the spatial location of proteins, their functional motifs and their binding sites. We show that for transferrin-coated polystyrene nanoparticles only a minority of adsorbed proteins exhibit functional motifs and the spatial organization appears random, which is consistent, overall, with a stochastic and irreversible adsorption process. Our methods are applicable to a wide array of nanoparticles and can offer a microscopic molecular description of the biological identity of nanoparticles.

Integrative Biology c1ib00029b

Electronic modification on Au-Pd catalyst by bismuth

Gold colloidal nanoparticles stabilized by neutral ligands and peptides

Abstract Gold colloidal nanoparticles stabilized by neutral ligands and peptides/F. Porta, V. Dal... more

Silver Gas Diffusion Electrode for Volatile Organic Halocompound Conversion to Hydrocarbons

Abstract Silver Gas Diffusion Electrode for Volatile Organic Halocompound Conversion to Hydrocarb... more

Preparation, Characterisation and Biological Applications of Gold Nanoparticles

... nanoparticles for biological applications, in this PhD project two active components of Aloe ... more ... nanoparticles for biological applications, in this PhD project two active components of Aloe vera, Aloin A and ... Fabris, L., Antonello, S., Armelao, L., Donkers, RL, Polo, F., Toniolo, C., Maran, FJ Am. ... Porta, Francesca; Krpetić, eljka; Prati, Laura; Gaiassi, Aureliano; Scarì, Giorgio. ...

Direct optical ultrasensitive analysis of DNA duplexes

Conjugation of PEG and gold nanoparticles to increase the accessibility and valency of tethered RNA splicing enhancers

Chem. Sci., 2012

Since alternative splicing patterns are exhibited by most mammalian genes, the functional propert... more Since alternative splicing patterns are exhibited by most mammalian genes, the functional properties of a gene may be changed for therapeutic purposes by nudging splicing from one pattern to another. Splicing to a refractory exon can be enhanced using bifunctional targeted oligonucleotide enhancers of splicing (TOES), which anneal to a target exon and carry additional sequence motifs to recruit activator proteins.

Nanomaterials: Impact on Cells and Cell Organelles

Nanomaterial, 2014

Colloidal nanoparticles designed for the interactions with cells are very small, nanoscale object... more Colloidal nanoparticles designed for the interactions with cells are very small, nanoscale objects usually consisting of inorganic cores and organic shells that are dispersed in a buffer or biological medium. Tuning the material properties the nanoparticles are made from, a number of different properties that can be exploited in specific biological applications are possible, i.e. targeting, labelling, drug delivery, use as diagnostic tools or therapy. For all biological applications of nanoparticles, it is important to understand their interactions with the surrounding biological environment in order to predict their biological impact, in particular when designing the nanoparticles for diagnostic and therapeutic purpose. Due to the high surface-to-volume ratio, the surface of nanomaterials is very reactive. When exposed to biological fluids, the proteins and biomolecules present therein tend to associate with the nanoparticles' surfaces. This phenomenon is defined as biomolecular corona formation. The biomolecular corona plays a key role in the interaction between nanoparticles and biological systems, impacting on how these particles interact with biological systems on a cellular and molecular level. This book chapter describes the nature of the interactions at the bio-nano interface, shows the design strategy of nanoparticles for nanomedicine, and defines the concepts of biomolecular corona and biological identity of nanoparticles. Moreover, it describes the interaction of functionalised nanomaterials with cell organelles and intracellular fate of nanoparticles and it shows therapeutic application of gold nanoparticles as dose enhancers in radiotherapy.

Interactions of Gold Nanoparticles with a Phospholipid Monolayer Membrane on Mercury

by Zeljka Krpetic, Mathias Brust, and Gabriel Gordillo

ACS Nano, 2014

It is demonstrated that a compact monolayer of 1,2-dioleoyl-sn-glycero-3-phosphocholine adsorbed ... more It is demonstrated that a compact monolayer of 1,2-dioleoyl-sn-glycero-3-phosphocholine adsorbed to a hanging mercury drop electrode can serve as a simple electrochemical model system to study biomembrane penetration by gold nanoparticles. The hydrogen redoxchemistry characteristic of ligand-stabilized gold nanoparticles in molecularly close contact with a mercury electrode is used as an indicator of membrane penetration. Results for water-dispersible gold nanoparticles of two different sizes are reported, and comparisons are made with the cellular uptake of the same preparations of nanoparticles by a common human fibroblast cell line. The experimental system described here can be used to study physicochemical aspects of membrane penetration in the absence of complex biological mechanisms, and it could also be a starting point for the development of a test bed for the toxicity of nanomaterials.

Direct surface-enhanced Raman scattering analysis of DNA duplexes

by Ramón Alvarez-puebla, Zeljka Krpetic, and Duncan Graham

Angewandte Chemie (International ed. in English), Jan 19, 2015

The exploration of the genetic information carried by DNA has become a major scientific challenge... more The exploration of the genetic information carried by DNA has become a major scientific challenge. Routine DNA analysis, such as PCR, still suffers from important intrinsic limitations. Surface-enhanced Raman spectroscopy (SERS) has emerged as an outstanding opportunity for the development of DNA analysis, but its application to duplexes (dsDNA) has been largely hampered by reproducibility and/or sensitivity issues. A simple strategy is presented to perform ultrasensitive direct label-free analysis of unmodified dsDNA with the means of SERS by using positively charged silver colloids. Electrostatic adhesion of DNA promotes nanoparticle aggregation into stable clusters yielding intense and reproducible SERS spectra at nanogram level. As potential applications, we report the quantitative recognition of hybridization events as well as the first examples of SERS recognition of single base mismatches and base methylations (5-methylated cytosine and N6-methylated Adenine) in duplexes.

Intracellular mapping with SERS-encoded gold nanostars

Integrative Biology, 2011

Here we report on the design, synthesis and application of small, highly bright, star-shaped SERS... more Here we report on the design, synthesis and application of small, highly bright, star-shaped SERS encoded single nanoparticles with the ability of providing an optical signal upon excitation with near infrared light. These particles are colloidally stable, fully biocompatible and can be internalized into living cells for intracellular imaging.

Energy Dependence of Gold Nanoparticle Radiosensitization in Plasmid DNA

by Jonathan Coulter, Suneil Jain, Karl Butterworth, and Zeljka Krpetic

The Journal of Physical Chemistry C, 2011

Importance of Nanoparticle Size in Colorimetric and SERS-Based Multimodal Trace Detection of Ni(II) Ions with Functional Gold Nanoparticles

Small, 2012

Acrylate-Facilitated Cellular Uptake of Gold Nanoparticles

by Ian Prior, Mathias Brust, and Zeljka Krpetic

Small, 2011

A multidentate peptide for stabilization and facile bioconjugation of gold nanoparticles

by Francesca Porta and Zeljka Krpetic

Gold nanoparticles of two different sizes stabilized by a 15-mer peptide ligand specifically desi... more Gold nanoparticles of two different sizes stabilized by a 15-mer peptide ligand specifically designed for this purpose have been prepared in aqueous solution and characterized by UV-vis spectroscopy and TEM. The presence of the ligand and its binding mode to the particles via its four cystein thiols is evidenced by FTIR and NMR spectroscopy. Biotinylation of the particles via binding to a freely accessible lysine residue is demonstrated.

Preparation and Characterisation of Au Nanoparticles Capped with Mercaptocarboranyl Clusters

Dalton Transactions

11 SI Integrative Biol

17 Conjugation of PEG and gold nanoparticles to increase the accessibility and valency of tethered RNA splicing enhancers SI

Electroreductions on Silver-Based Electrocatalysts: The Use of Ag Nanoparticles for CHCl 3 to CH 4 Conversion

Fuel Cells, 2009

A preliminary investigation on a new class on electrocatalytic materials for the electroreduction... more A preliminary investigation on a new class on electrocatalytic materials for the electroreduction of organic halides is presented and discussed. The electrocatalysts are based on silver nanoparticles (Ag_NP), ad hoc synthesised by chemical reduction of an aqueous silver salt in the presence of six different stabilising agents. The colloids are then supported on carbon powder (10% loading) for further characterisation and use. The electrocatalytic properties of the Ag_NP/carbon composites towards the dehalogenation of halocompounds are tested by cyclic voltammetry and by preparative electrolysis. The hydrodehalogenation of trichloromethane, extensively studied by this group, is selected as a model reaction, because of its relevance for the detoxification of wastes. The voltammetric characterisation is performed in an aqueous solution, supporting the composites on cavity microelectrodes. Gas-diffusion electrodes (GDE) based on the most promising Ag_NP composite -and, for reference, on a commercial Ag/C oxygen reduction electrocatalystare then tested in an electrolytic process for the progressive conversion of gaseous trichloromethane to less chlorinated compounds, and ultimately to methane.

Mapping protein binding sites on the biomolecular corona of nanoparticles

Nature Nanotechnology, 2015

Nanoparticles in a biological milieu are known to form a sufficiently long-lived and well-organiz... more Nanoparticles in a biological milieu are known to form a sufficiently long-lived and well-organized &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;corona&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; of biomolecules to confer a biological identity to the particle. Because this nanoparticle-biomolecule complex interacts with cells and biological barriers, potentially engaging with different biological pathways, it is important to clarify the presentation of functional biomolecular motifs at its interface. Here, we demonstrate that by using antibody-labelled gold nanoparticles, differential centrifugal sedimentation and various imaging techniques it is possible to identify the spatial location of proteins, their functional motifs and their binding sites. We show that for transferrin-coated polystyrene nanoparticles only a minority of adsorbed proteins exhibit functional motifs and the spatial organization appears random, which is consistent, overall, with a stochastic and irreversible adsorption process. Our methods are applicable to a wide array of nanoparticles and can offer a microscopic molecular description of the biological identity of nanoparticles.

Integrative Biology c1ib00029b

Electronic modification on Au-Pd catalyst by bismuth

Gold colloidal nanoparticles stabilized by neutral ligands and peptides

Abstract Gold colloidal nanoparticles stabilized by neutral ligands and peptides/F. Porta, V. Dal... more

Silver Gas Diffusion Electrode for Volatile Organic Halocompound Conversion to Hydrocarbons

Abstract Silver Gas Diffusion Electrode for Volatile Organic Halocompound Conversion to Hydrocarb... more

Preparation, Characterisation and Biological Applications of Gold Nanoparticles

... nanoparticles for biological applications, in this PhD project two active components of Aloe ... more ... nanoparticles for biological applications, in this PhD project two active components of Aloe vera, Aloin A and ... Fabris, L., Antonello, S., Armelao, L., Donkers, RL, Polo, F., Toniolo, C., Maran, FJ Am. ... Porta, Francesca; Krpetić, eljka; Prati, Laura; Gaiassi, Aureliano; Scarì, Giorgio. ...

Direct optical ultrasensitive analysis of DNA duplexes

Conjugation of PEG and gold nanoparticles to increase the accessibility and valency of tethered RNA splicing enhancers

Chem. Sci., 2012

Since alternative splicing patterns are exhibited by most mammalian genes, the functional propert... more Since alternative splicing patterns are exhibited by most mammalian genes, the functional properties of a gene may be changed for therapeutic purposes by nudging splicing from one pattern to another. Splicing to a refractory exon can be enhanced using bifunctional targeted oligonucleotide enhancers of splicing (TOES), which anneal to a target exon and carry additional sequence motifs to recruit activator proteins.

Nanomaterials: Impact on Cells and Cell Organelles

Nanomaterial, 2014

Colloidal nanoparticles designed for the interactions with cells are very small, nanoscale object... more Colloidal nanoparticles designed for the interactions with cells are very small, nanoscale objects usually consisting of inorganic cores and organic shells that are dispersed in a buffer or biological medium. Tuning the material properties the nanoparticles are made from, a number of different properties that can be exploited in specific biological applications are possible, i.e. targeting, labelling, drug delivery, use as diagnostic tools or therapy. For all biological applications of nanoparticles, it is important to understand their interactions with the surrounding biological environment in order to predict their biological impact, in particular when designing the nanoparticles for diagnostic and therapeutic purpose. Due to the high surface-to-volume ratio, the surface of nanomaterials is very reactive. When exposed to biological fluids, the proteins and biomolecules present therein tend to associate with the nanoparticles' surfaces. This phenomenon is defined as biomolecular corona formation. The biomolecular corona plays a key role in the interaction between nanoparticles and biological systems, impacting on how these particles interact with biological systems on a cellular and molecular level. This book chapter describes the nature of the interactions at the bio-nano interface, shows the design strategy of nanoparticles for nanomedicine, and defines the concepts of biomolecular corona and biological identity of nanoparticles. Moreover, it describes the interaction of functionalised nanomaterials with cell organelles and intracellular fate of nanoparticles and it shows therapeutic application of gold nanoparticles as dose enhancers in radiotherapy.

Interactions of Gold Nanoparticles with a Phospholipid Monolayer Membrane on Mercury

by Zeljka Krpetic, Mathias Brust, and Gabriel Gordillo

ACS Nano, 2014

It is demonstrated that a compact monolayer of 1,2-dioleoyl-sn-glycero-3-phosphocholine adsorbed ... more It is demonstrated that a compact monolayer of 1,2-dioleoyl-sn-glycero-3-phosphocholine adsorbed to a hanging mercury drop electrode can serve as a simple electrochemical model system to study biomembrane penetration by gold nanoparticles. The hydrogen redoxchemistry characteristic of ligand-stabilized gold nanoparticles in molecularly close contact with a mercury electrode is used as an indicator of membrane penetration. Results for water-dispersible gold nanoparticles of two different sizes are reported, and comparisons are made with the cellular uptake of the same preparations of nanoparticles by a common human fibroblast cell line. The experimental system described here can be used to study physicochemical aspects of membrane penetration in the absence of complex biological mechanisms, and it could also be a starting point for the development of a test bed for the toxicity of nanomaterials.

Direct surface-enhanced Raman scattering analysis of DNA duplexes

by Ramón Alvarez-puebla, Zeljka Krpetic, and Duncan Graham

Angewandte Chemie (International ed. in English), Jan 19, 2015

The exploration of the genetic information carried by DNA has become a major scientific challenge... more The exploration of the genetic information carried by DNA has become a major scientific challenge. Routine DNA analysis, such as PCR, still suffers from important intrinsic limitations. Surface-enhanced Raman spectroscopy (SERS) has emerged as an outstanding opportunity for the development of DNA analysis, but its application to duplexes (dsDNA) has been largely hampered by reproducibility and/or sensitivity issues. A simple strategy is presented to perform ultrasensitive direct label-free analysis of unmodified dsDNA with the means of SERS by using positively charged silver colloids. Electrostatic adhesion of DNA promotes nanoparticle aggregation into stable clusters yielding intense and reproducible SERS spectra at nanogram level. As potential applications, we report the quantitative recognition of hybridization events as well as the first examples of SERS recognition of single base mismatches and base methylations (5-methylated cytosine and N6-methylated Adenine) in duplexes.

Intracellular mapping with SERS-encoded gold nanostars

Integrative Biology, 2011

Here we report on the design, synthesis and application of small, highly bright, star-shaped SERS... more Here we report on the design, synthesis and application of small, highly bright, star-shaped SERS encoded single nanoparticles with the ability of providing an optical signal upon excitation with near infrared light. These particles are colloidally stable, fully biocompatible and can be internalized into living cells for intracellular imaging.

Energy Dependence of Gold Nanoparticle Radiosensitization in Plasmid DNA

by Jonathan Coulter, Suneil Jain, Karl Butterworth, and Zeljka Krpetic

The Journal of Physical Chemistry C, 2011

Importance of Nanoparticle Size in Colorimetric and SERS-Based Multimodal Trace Detection of Ni(II) Ions with Functional Gold Nanoparticles

Small, 2012

Acrylate-Facilitated Cellular Uptake of Gold Nanoparticles

by Ian Prior, Mathias Brust, and Zeljka Krpetic

Small, 2011