Ivonne Olmedo

University of Texas Medical School, Houston, Texas, United States

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Publications (7)20.5 Total impact

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    ABSTRACT: Functionalization of gold nanoparticles (AuNPs) with both a targeting peptide (an analogue of the peptide Bombesin) and a drug peptide ligand (an analogue of the RAF peptide) with the aim of improving selectivity in the delivery of the conjugates as well as the antitumor activity is described. Studies on the internalization mechanism of peptide-AuNP conjugates and viability of cells were carried out. An enhancement of the activity and selectivity of the peptide multifunctionalized conjugates was observed.
    Bioconjugate Chemistry 06/2010; 21(6):1070-8. · 4.58 Impact Factor
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    ABSTRACT: Gold nanoparticles (GNPs) offer a great promise in biomedicine. Currently, there is no data available regarding the accumulation of nanoparticles in vivo after repeated administration. The purpose of the present study was to evaluate the bioaccumulation and toxic effects of different doses (40, 200, and 400 microg/kg/day) of 12.5 nm GNPs upon intraperitoneal administration in mice every day for 8 days. The gold levels in blood did not increase with the dose administered, whereas in all the organs examined there was a proportional increase on gold, indicating efficient tissue uptake. Although brain was the organ containing the lowest quantity of injected GNPs, our data suggest that GNPs are able to cross the blood-brain barrier and accumulate in the neural tissue. Importantly, no evidence of toxicity was observed in any of the diverse studies performed, including survival, behavior, animal weight, organ morphology, blood biochemistry and tissue histology. The results indicate that tissue accumulation pattern of GNPs depend on the doses administered and the accumulation of the particles does not produce sub-acute physiological damage.
    Biochemical and Biophysical Research Communications 02/2010; 393(4):649-55. · 2.41 Impact Factor
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    02/2009: pages 45-80; , ISBN: 9783527319367
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    ABSTRACT: A new synthesis and stabilization method was developed for paramagnetic nanoparticles composed of nickel and nickel oxides. Nickel/nickel oxides nanoparticles were synthesized by a method based on ligand displacement of bis(1,5-cyclooctadiene)-nickel(0), zerovalent organometallic precursor and simultaneous formation of a thiourea inclusion compound. Nickel/nickel oxides nanoparticles were stabilized with the amphipathic peptide H2N-Cys-Leu-Pro-Phe-Phe-Asp-NH2 having H2N-Leu-Pro-Phe-Phe-Asp-NH2 a peptide with potential properties for Alzheimer's disease therapy. The inclusion compound formed after displacement was characterized by X-ray powder diffraction, and nickel/nickel oxides nanoparticles were characterized using transmission electron microscopy, atomic force microscopy, UV-Visible spectroscopy, X-ray photoelectron spectroscopy, and superconducting quantum interference device magnetometry. In addition, a cell viability assay in primary rat hippocampal neurons was carried out.
    Journal of Nanoscience and Nanotechnology 09/2008; 8(8):3820-7. · 1.15 Impact Factor
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    ABSTRACT: In a previous work, we studied the interaction of beta-amyloid fibrils (Abeta) with gold nanoparticles (AuNP) conjugated with the peptide CLPFFD-NH2. Here, we studied the effect of changing the residue sequence of the peptide CLPFFD-NH2 on the efficiency of conjugation to AuNP, the stability of the conjugates, and the affinity of the conjugates to the Abeta fibrils. We conjugated the AuNP with CLPFFD-NH 2 isomeric peptides (CDLPFF-NH2 and CLPDFF-NH2) and characterized the resulting conjugates with different techniques including UV-Vis, TEM, EELS, XPS, analysis of amino acids, agarose gel electrophoresis, and CD. In addition, we determined the proportion of AuNP bonded to the Abeta fibrils by ICP-MS. AuNP-CLPFFD-NH2 was the most stable of the conjugates and presented more affinity for Abeta fibrils with respect to the other conjugates and bare AuNP. These findings help to better understand the way peptide sequences affect conjugation and stability of AuNP and their interaction with Abeta fibrils. The peptide sequence, the steric effects, and the charge and disposition of hydrophilic and hydrophobic residues are crucial parameters when considering the design of AuNP peptide conjugates for biomedical applications.
    Bioconjugate Chemistry 07/2008; 19(6):1154-63. · 4.58 Impact Factor
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    ABSTRACT: Peptide-Gold nanoparticles selectively attached to beta-amyloid protein (A beta) amyloidogenic aggregates were irradiated with microwave. This treatment produces dramatic effects on the A beta aggregates, inhibiting both the amyloidogenesis and the restoration of the amyloidogenic potential. This novel approach offers a new strategy to inhibit, locally and remotely, the amyloidogenic process, which could have application in Alzheimer's disease therapy. We have studied the irradiation effect on the amyloidogenic process in the presence of conjugates peptide-nanoparticle by transmission electronic microscopy observations and by Thioflavine T assays to quantify the amount of fibrils in suspension. The amyloidogenic aggregates rather than the amyloid fibrils seem to be better targets for the treatment of the disease. Our results could contribute to the development of a new therapeutic strategy to inhibit the amyloidogenic process in Alzheimer's disease. This work was supported by FONDECYT 1061142, FONDAP 11980002 (17 07 0002), and AECI A/010967/07.
    Nanoscale Research Letters 01/2008; · 2.52 Impact Factor
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    ABSTRACT: In this review, we describe the contribution of peptides to the biomedical applications of metallic nanoparticles. We also discuss strategies for the preparation of peptide-nanoparticle conjugates and the synthesis of the peptides and metallic nanoparticles. An overview of the techniques used for the characterization of the conjugates is also provided. Mainly for biomedical purposes, metallic nanoparticles conjugated to peptides have been prepared from Au and iron oxide (magnetic nanoparticles). Peptides with the capacity to penetrate the plasma membrane are used to deliver nanoparticles to the cell. In addition, peptides that recognize specific cell receptors are used for targeting nanoparticles. The potential application of peptide-nanoparticle conjugates in cancer and Alzheimer's disease therapy is discussed. Several peptide-nanoparticle conjugates show biocompatibility and present a low degree of cytotoxicity. Furthermore, several peptide-metallic nanoparticle conjugates are used for in vitro diagnosis.
    Nanomedicine 07/2007; 2(3):287-306. · 5.26 Impact Factor