liu.seSearch for publications in DiVA
Change search
Link to record
Permanent link

Direct link
BETA
Petoral, Rodrigo M
Alternative names
Publications (10 of 41) Show all publications
Petoral, R. M., Söderlind, F., Klasson, A., Suska, A., Fortin, M.-A., Abrikossova, N., . . . Uvdal, K. (2009). Synthesis and Characterization of Tb3+-Doped Gd2O3 Nanocrystals: A Bifunctional Material with Combined Fluorescent Labeling and MRI Contrast Agent Properties. The Journal of Physical Chemistry C, 113(17), 6913-6920
Open this publication in new window or tab >>Synthesis and Characterization of Tb3+-Doped Gd2O3 Nanocrystals: A Bifunctional Material with Combined Fluorescent Labeling and MRI Contrast Agent Properties
Show others...
2009 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 113, no 17, p. 6913-6920Article in journal (Refereed) Published
Abstract [en]

Ultrasmall gadolinium oxide nanoparticles doped with terbium ions were synthesized by the polyol route and characterized as a potentially bifunctional material with both fluorescent and magnetic contrast agent properties. The structural, optical, and magnetic properties of the organic-acid-capped and PEGylated Gd2O3:Tb3+ nanocrystals were studied by HR-TEM, XPS, EDX, IR, PL, and SQUID. The luminescent/fluorescent property of the particles is attributable to the Tb3+ ion located on the crystal lattice of the Gd2O3 host. The paramagnetic behavior of the particles is discussed. Pilot studies investigating the capability of the nanoparticles for fluorescent labeling of living cells and as a MRI contrast agent were also performed. Cells of two cell lines (THP-1 cells and fibroblasts) were incubated with the particles, and intracellular particle distribution was visualized by confocal microscopy. The MRI relaxivity of the PEGylated nanoparticles in water at low Gd concentration was assessed showing a higher T-1 relaxation rate compared to conventional Gd-DTPA chelates and comparable to that of undoped Gd2O3 nanoparticles.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-12944 (URN)10.1021/jp808708m (DOI)000265529700009 ()
Note

On the day of the defence date the status of this article was Submitted

Available from: 2008-02-21 Created: 2008-02-21 Last updated: 2018-10-29Bibliographically approved
Söderlind, F., Fortin, M. A., Petoral, R. M., Klasson, A., Veres, T., Engström, M., . . . Käll, P.-O. (2008). Colloidal synthesis and characterization of ultrasmall perovskite GdFeO3 nanocrystals. Nanotechnology, 19(8), 085608
Open this publication in new window or tab >>Colloidal synthesis and characterization of ultrasmall perovskite GdFeO3 nanocrystals
Show others...
2008 (English)In: Nanotechnology, ISSN 0957-4484, Vol. 19, no 8, p. 085608-Article in journal (Refereed) Published
Abstract [en]

Synthesis of very small (about 4 nm) perovskite structured gadolinium orthoferrite nanoparticles (GdFeO3) was performed by the polyol method. The material shows promising relaxivity properties and potential as a contrast agent in magnetic resonance imaging. The perovskite nanoparticles were characterized by x-ray diffraction, transmission electron microscopy, energy dispersive x-ray spectroscopy, Fourier transform infrared spectroscopy, magnetic resonance, and magnetization measurements. Upon heating in air at 800 °C for 3 h the size of the crystals increased to about 40 nm. The crystalline structure of the heat treated compound is in good agreement with perovskite GdFeO3 as the primary product. Contributions from various secondary phases were also identified, including one hitherto unknown phase with the suggested composition 'Gd3FeO6' and isostructural with Gd3GaO6. The novel 'Gd3FeO6' phase appears to be kinetically stabilized in the nano state.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-13298 (URN)10.1088/0957-4484/19/8/085608 (DOI)000252967400014 ()
Available from: 2008-05-21 Created: 2008-05-21 Last updated: 2015-10-09
Björefors, F., Petoral Jr, R. M. & Uvdal, K. (2007). Electrochemical impedance spectroscopy for investigations on ion permeation in ?-functionalized self-assembled monolayers. Analytical Chemistry, 79(21), 8391-8398
Open this publication in new window or tab >>Electrochemical impedance spectroscopy for investigations on ion permeation in ?-functionalized self-assembled monolayers
2007 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 79, no 21, p. 8391-8398Article in journal (Refereed) Published
Abstract [en]

Electrochemical impedance spectroscopy was employed to explore the possibility of relating the permeation of electrolyte ions in ?-functionalized self-assembled monolayers to structural or polarity changes induced by interaction with metal ions. The monolayers were based on alkanethiols modified with a phosphorylated tyrosine analogue, which from previous work are known to drastically change their organization on gold surfaces upon interaction with aluminum and magnesium ions. The ion permeation was evaluated by using relatively low excitation frequencies, 1000 to 2 Hz, and quantified by an extra resistive component in the equivalent circuit (R SAM). The extent of ion permeation influenced by the dc potential, the electrolyte concentration, the functional group, and the thiol length were also investigated. It was, for example, found that RSAM decreased ~20% when the thiol organization collapsed and that RSAM increased ~4-5 times when the electrolyte concentration was decreased by 1 order of magnitude. Interesting observations were also made regarding the potential dependence of RSAM and the double layer capacitance. The evaluation of the ion permeation can be used to indirectly detect whether the organization of a SAM is influenced by, for example, electric fields or chemical and biological interactions. This analysis can be performed without addition of redox species, but is on the other hand complicated by the fact that other factors also influence the presence of ions within the monolayer. In addition, a second parallel RC process was obtained in some of the impedance spectra when using even lower frequencies, and its resistive component revealed different results compared to RSAM. Such data may be useful for the understanding of complex double layer phenomena at modified electrodes. © 2007 American Chemical Society.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-47878 (URN)10.1021/ac071399d (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
Savitchi, L., Vahlberg, C., Petoral, R. J. & Uvdal, K. (2007). Mixed monolayers to promote G-protein adsorption: α2A- Adrenergic receptor-derived peptides coadsorbed with formyl-terminated oligopeptides. Langmuir, 23(16), 8474-8479
Open this publication in new window or tab >>Mixed monolayers to promote G-protein adsorption: α2A- Adrenergic receptor-derived peptides coadsorbed with formyl-terminated oligopeptides
2007 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 23, no 16, p. 8474-8479Article in journal (Refereed) Published
Abstract [en]

Pure and mixed monolayers of a synthetic peptide, GPR-i3n, derived from the third intracellular loop of the α2 adrenergic receptor and a shorter inactive oligopeptide, N-formyl-(Gly)3-(Cys) (called 3GC), were prepared on gold surfaces. The mixing ratio of the GPR-i3n and 3GC was used to control G-protein binding capability. The GPR-i3n peptide is specially designed for bovine G-protein selectivity and has been proven to have high affinity to G-proteins [Vahlberg, C.; Petoral, R. M., Jr.; Lindell, C.; Broo, K.; Uvdal, K. Langmuir 2006, 22 (17), 7260−7264]. Pure 3GC monolayers show very low protein adsorption capability. In this study, 3GC is chosen as a coadsorbent, with the aim to induce molecular conformational changes during monolayer formation to enhance G-protein adsorption. A full characterization of the mixed monolayers was done. The monolayer thickness and the mass-related surface coverage for both GPR-i3n and 3GC were investigated using radio labeling. The GPR-i3n was labeled by 125I-targeting tyrosine, and the activity was measured by using radioimmunoassay (RIA). The formation and chemical composition of GPR-i3n and 3GC monolayers were investigated using X-ray photoelectron spectroscopy, and it is shown that both GPR-i3n and 3GC bind chemically to the gold surface. The interaction between the mixed monolayers and G-proteins was investigated by means of real-time surface plasmon resonance. There is a higher protein binding capacity to the monolayer when the GPR-i3n peptide is intermixed with the 3GC coadsorbent, despite the fact that the 3GC itself has a very low G-protein binding capability. This supports a molecular reorientation at the surface, while 3GC is intermixed with GPR-i3n.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-47944 (URN)10.1021/la063447f (DOI)000248229900028 ()
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13Bibliographically approved
Vahlberg, C., Petoral, R. J., Carlsson, A., Broo, K. & Uvdal, K. (2007). Neurotransmitter Derivatives Adsorbed on Gold. In: IVC-17/ICSS-13 ICNT,2007.
Open this publication in new window or tab >>Neurotransmitter Derivatives Adsorbed on Gold
Show others...
2007 (English)In: IVC-17/ICSS-13 ICNT,2007, 2007Conference paper, Published paper (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44595 (URN)77165 (Local ID)77165 (Archive number)77165 (OAI)
Note
Conference proceedingsAvailable from: 2009-10-10 Created: 2009-10-10
Yakimova, R., Steinhoff, G., Petoral, R. J., Vahlberg, C., Khranovskyy, V., Yazdi, G., . . . Lloyd Spetz, A. (2007). Novel material concepts of transducers for chemical and biosensors. Biosensors & bioelectronics, 22(12), 2780-2785
Open this publication in new window or tab >>Novel material concepts of transducers for chemical and biosensors
Show others...
2007 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 22, no 12, p. 2780-2785Article in journal (Refereed) Published
Abstract [en]

The objectives of this work are to contribute to the knowledge about physical and chemical properties of WBG semiconductors, such as ZnO and GaN towards development of advanced bio- and chemical sensors. For the semiconductors, growth techniques typically yielding single crystal material are applied. Thin epitaxial quality films of ZnO and GaN are fabricated on SiC or sapphire substrates. An emphasis is given to ZnO due to the interesting combination of the semiconductor and oxide properties. Surface bio-functionalization of ZnO is performed by APTES, MPA or MP-TMS molecules. We have compared some of the results to (hydroxylated) GaN surfaces functionalized by MP-TMS. The covalent attachment of the self-assembled biomolecular layers has been proven by XPS analysis. For complementary electrical characterization impedance spectroscopy measurements were performed. The results are intended to serve the realization of bioelectronic transducer devices based on SiC or GaN transistors with a ZnO gate layer. To take advantage of the catalytic properties of ZnO, initial prototypes of chemical sensors for gas sensing are processed on ZnO deposited either on SiC or on sapphire and they are further tested for the response to reducing or oxidizing gas ambient. The sensor devices show sensitivity to oxygen in the surface resistivity mode while a Pt Schottky contact ZnO/SiC device responds to reducing gases. These results are compared to published results on Pt/GaN Schottky diodes. © 2007 Elsevier B.V. All rights reserved.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-38763 (URN)10.1016/j.bios.2006.12.032 (DOI)45537 (Local ID)45537 (Archive number)45537 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
Petoral, R. J., Yazdi, G., Lloyd-Spets, A., Yakimova, R. & Uvdal, K. (2007). Organosilane-functionalized wide band gap semiconductor surfaces. Applied Physics Letters, 90(22)
Open this publication in new window or tab >>Organosilane-functionalized wide band gap semiconductor surfaces
Show others...
2007 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, no 22Article in journal (Refereed) Published
Abstract [en]

Surface functionalization of wide band gap semiconductors, SiC, ZnO, and GaN, with organosilane is reported. Formation of self-assembled monolayers of mercaptopropyltrimethoxysilane is confirmed by x-ray photoelectron spectroscopy and atomic force microscopy. The molecules are adsorbed on the surfaces through the silane groups with the free thiol groups molecularly oriented away from the surface. Moreover, chemisorption via the thiolate is observed for the ZnO surface. Immobilization of a model biomolecule to the functionalized surface is demonstrated. An amino acid derivative, i.e., phosphotyrosine derived thiol, is linked on the functionalized ZnO and GaN surfaces via formation of disulfide bridges. © 2007 American Institute of Physics.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-49421 (URN)10.1063/1.2745641 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-12
Fortin, M.-A., Petoral Jr, R. M., Söderlind, F., Klasson, A., Engström, M., Veres, T., . . . Uvdal, K. (2007). Polyethylene glycol-cover ultra-small Gd2O3 nanoparticles for positive contras at 1.5 T magnetic resonance clinical scanning. Nanotechnology, 18(39), 395501
Open this publication in new window or tab >>Polyethylene glycol-cover ultra-small Gd2O3 nanoparticles for positive contras at 1.5 T magnetic resonance clinical scanning
Show others...
2007 (English)In: Nanotechnology, ISSN 0957-4484, Vol. 18, no 39, p. 395501-Article in journal (Refereed) Published
Abstract [en]

The size distribution and magnetic properties of ultra-small gadolinium oxide crystals (US-Gd2O3) were studied, and the impact of polyethylene glycol capping on the relaxivity constants (r1, r2) and signal intensity with this contrast agent was investigated. Size distribution and magnetic properties of US-Gd2O3 nanocrystals were measured with a TEM and PPMS magnetometer. For relaxation studies, diethylene glycol (DEG)-capped US-Gd2O3 nanocrystals were reacted with PEG-silane (MW 5000). Suspensions were adequately dialyzed in water to eliminate traces of Gd3+ and surfactants. The particle hydrodynamic radius was measured with dynamic light scattering (DLS) and the proton relaxation times were measured with a 1.5 T MRI scanner. Parallel studies were performed with DEG–Gd2O3 and PEG-silane–SPGO (Gd2O3,< 40 nm diameter). The small and narrow size distribution of US-Gd2O3 was confirmed with TEM (~3 nm) and DLS. PEG-silane–US-Gd2O3 relaxation parameters were twice as high as for Gd–DTPA and the r2/r1 ratio was 1.4. PEG-silane–SPGO gave low r1 relaxivities and high r2/r1 ratios, less compatible with positive contrast agent requirements. Higher r1 were obtained with PEG-silane in comparison to DEG–Gd2O3. Treatment of DEG–US-Gd2O3 with PEG-silane provides enhanced relaxivity while preventing aggregation of the oxide cores. This study confirms that PEG-covered Gd2O3 nanoparticles can be used for positively contrasted MR applications requiring stability, biocompatible coatings and nanocrystal functionalization.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-13297 (URN)10.1088/0957-4484/18/39/395501 (DOI)000249283300006 ()
Available from: 2008-05-21 Created: 2008-05-21 Last updated: 2015-12-17
Ahrén, M., Olsson, P., Söderlind, F., Klasson, A., Petoral, R. J., Engström, M., . . . Uvdal, K. (2007). Rare earth nanoparticles as contrast agent in MRI: Nanomaterial design and biofunctionalization. In: IVC-17/ICSS-13 ICNT,2007.
Open this publication in new window or tab >>Rare earth nanoparticles as contrast agent in MRI: Nanomaterial design and biofunctionalization
Show others...
2007 (English)In: IVC-17/ICSS-13 ICNT,2007, 2007Conference paper, Published paper (Other academic)
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-44593 (URN)77163 (Local ID)77163 (Archive number)77163 (OAI)
Note
Conference proceedingsAvailable from: 2009-10-10 Created: 2009-10-10 Last updated: 2010-07-01
Yakimova, R., Petoral, R. J., Yazdi, G., Vahlberg, C., Lloyd Spetz, A. & Uvdal, K. (2007). Surface functionalization and biomedical applications based on SiC. Journal of Physics D: Applied Physics, 40(20), 6435-6442
Open this publication in new window or tab >>Surface functionalization and biomedical applications based on SiC
Show others...
2007 (English)In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 40, no 20, p. 6435-6442Article in journal (Refereed) Published
Abstract [en]

The search for materials and systems, capable of operating long term under physiological conditions, has been a strategy for many research groups during the past years. Silicon carbide (SiC) is a material, which can meet the demands due to its high biocompatibility, high inertness to biological tissues and to aggressive environment, and the possibility to make all types of electronic devices. This paper reviews progress in biomedical and biosensor related research on SiC. For example, less biofouling and platelet aggregation when exposed to blood is taken advantage of in a variety of medical implantable materials while the robust semiconducting properties can be explored in surface functionalized bioelectronic devices. © 2007 IOP Publishing Ltd.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-38765 (URN)10.1088/0022-3727/40/20/S20 (DOI)45539 (Local ID)45539 (Archive number)45539 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13
Organisations

Search in DiVA

Show all publications