Marcelo J Kogan

University of Santiago, Chile, CiudadSantiago, Santiago, Chile

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Publications (46)191.18 Total impact

  • Langmuir 12/2014; · 4.38 Impact Factor
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    ABSTRACT: We report here a systematic study of the antibacterial behavior of silver nanoparticles coated with fatty acids (oleic: AgNP-O, linoleic: AgNP-L, and palmitic acids: AgNP-P) in water. We have found remarkable differences in their capability to penetrate bacteria cell over a broader range of particle size of *4–96 nm compared to previously reported work, and a variable toxicity depending on the particles size. Our results indicate that silver nanoparticles stabilized with oleic acid showed clear advantages in antibacte-rial activity, penetration inside the bacteria cells, cytotoxicity, time effectiveness, efficiency, and sta-bility against light.
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    Journal of Nanoparticle Research 09/2014; 16(9):2465. · 2.18 Impact Factor
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    ABSTRACT: In this article, we describe how nanoparticles work in photothermally triggered drug delivery, starting with a description of the plasmon resonance and the photothermal effect, and how this is used to release a drug. Then, we describe the four major functionalization strategies and each of their different applications. Finally, we discuss the biodistribution and toxicity of these systems and the necessary requirements for the use of gold nanoparticles for spatially and temporally controlling drug release through the photothermal effect.
    Nanomedicine 09/2014; 9(13):2023-39. · 5.82 Impact Factor
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    ABSTRACT: In a previous work we demonstrated that toxic aggregates of the protein β-amyloid (ATAβ) involved in the Alzheimer's disease (AD) can be destabilized upon electromagnetic irradiation of the peptide Cys-Leu-Pro-Phe-Phe-Asp (CLPFFD) adsorbed on gold nanospheres (AuNSs). For a selective recognition of the therapeutic target (i.e. ATAβ) of AD by the conjugates peptide-nanoparticle it is relevant to understand how the interaction between attached ligands and nanoparticles occurs. In this work a surface enhanced Raman scattering spectroscopy (SERS) study of the interactions of CLPFFD with AuNSs of 10nm average diameter was carried out. The SERS data suggest that phenylalanine displays its aromatic ring coplanar to the surface which is supported by theoretical data obtained from molecular mechanics (MM) and Extended Hückel Theory (EHT) calculations.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 06/2014; 134C:251-256. · 2.13 Impact Factor
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    ABSTRACT: Antibacterial properties of silver(I)-pyridinedicarboxylate compounds (with Pyridine-2,3-dicarboxylic(Lutidinic acid), pyridine-2,4-dicarboxylic (Quinolinic acid) and pyridine-2,5-dicarboxylic (Isocinchomeronic acid)) were studied against Escherichia coli, Listeria monocytogenes (ISP-65-08), Salmonella typhi and Staphylococcus aureus (ATCC 25923) using kinetics of grown inhibition, viability assays, minimum inhibitory concentration and optical microscopy. The 3 silver compounds were tested toward UV-radiation in order to characterize their light insensitivity for potential medical devices: UV-radiation curable polymers. Photophysical measurements show remarkable differences toward UV-radiation, which were explained based on their polymeric structures with multiple nature bonds between pyridinedicarboxylic ligands and Ag(I) centers. We found a bacteriolytic effect and differences in the antibacterial efficiency depending on the structure of the complexes and the nature of AgX (X=oxygen and nitrogen) bonds: AgQuinol>AgLutidin>AgIsocinchom.
    Materials Science and Engineering C 04/2014; · 2.74 Impact Factor
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    ABSTRACT: In this article we review the flow chemistry methodologies for the controlled synthesis of different kind of nano and microparticles for biomedical applications. Injection mechanism has emerged as new alternative for the synthesis of nanoparticles due to this strategy allows achieving superior levels of control of self-assemblies, leading to higher-order structures and rapid chemical reactions. Self-assembly events are strongly dependent on factors such as the local concentration of reagents, the mixing rates, and the shear forces, which can be finely tuned, as an example, in a microfluidic device. Injection methods have also proved to be optimal to elaborate microsystems comprising polymer solutions. Concretely, extrusion based methods can provide controlled fluid transport, rapid chemical reactions, and cost-saving advantages over conventional reactors. We provide an update of synthesis of nano and microparticles such as core/shell, Janus, nanocrystals, liposomes, and biopolymeric microgels through flow chemistry, its potential bioapplications and future challenges in this field are discussed.
    Current topics in medicinal chemistry 01/2014; · 4.47 Impact Factor
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    ABSTRACT: Gold nanorods used in therapy and diagnosis must be nontoxic and stable in biological media and should be specific for the target. The complete combination of these three factors has hindered the use of gold nanorods as carriers in biological and biomedical applications. In this study, we produced a conjugate of gold nanorods with the peptide CLPFFD that recognizes toxic beta-amyloid aggregates present in Alzheimer's disease, demonstrates colloidal stability, maintains plasmonic properties and shows no effects on cell viability in the SH-SY5Y cell line. Furthermore, the irradiation of beta-amyloid in the presence of the conjugate with near infrared region irradiation energy reduces the amyloidogenic process reducing also its cytotoxicity. The nanorods were synthesized following the seed-mediated method in cetyltrimethylammonium bromide (CTAB) and were conjugated with the N-terminal cysteine peptide, CLPFFD. The conjugate was exhaustively characterized using different techniques (Absorption spectroscopy, x-ray photoelectron spectroscopy, electron energy loss spectroscopy and zeta potential). The effects on cell viability and cell penetration by transmission electron microscopy of the conjugate were evaluated. The chemisorption of the peptide on the surface of gold nanorods increases their stability and reduces their effects on cell viability.
    ACS Applied Materials & Interfaces 04/2013; · 5.90 Impact Factor
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    ABSTRACT: The antimicrobial effect of incorporating silver nanoparticles (AgNps) into zirconia matrixepolyether glycol was studied. AgNps of 4e6 nm in size were synthesized using the inverse micelles method, and different doses of metallic nanoparticles were incorporated into zirconiaepolyether glycol mixtures during the ageing procedure. Atomic force microscopy (AFM) of the modified hybrid film showed a homogenous distribution of 20e80 nm diameter AgNps, indicating agglomeration of these structures during film modification; such agglomerations were greater when increasing the dosage of the colloidal system. The AgNps-hybrid films showed higher antimicrobial activity against Gram-positive bacteria than for Gram-negative bacteria. Hybrid films prepared with dioctyl sodium sulfosuccinate (AOT) stabilized AgNps presented enhanced antibacterial activity compared to that obtained through the addition of a high AgNO3 concentration (0.3 wt%).
    Materials Chemistry and Physics 09/2012; 137:396-403. · 2.13 Impact Factor
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    ABSTRACT: Gold nanorods (AuNRs) stabilized by cetyltrimethylammonium bromide (CTAB) were deposited onto crystals of α-cyclodextrin (α-CD) inclusion compounds (ICs) that contained octanethiol (OT) as guest molecules. The nanodecoration was produced specifically at the {001} crystal planes through interaction between the -SH groups of the ICs and the AuNRs.
    Journal of Colloid and Interface Science 09/2012; 389(1):42-5. · 3.55 Impact Factor
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    ABSTRACT: The treatment of Alzheimer's disease and many other brain-related disorders is limited because of the presence of the blood-brain barrier, which highly regulate the crossing of drugs. Metal nanoparticles have unique features that could contribute to the development of new therapies for these diseases. Nanoparticles have the capacity to carry several molecules of a drug; furthermore, their unique physico-chemical properties allow, for example, photothermal therapy to produce molecular surgery to destroy tumor cells and toxic structures. Recently, we demonstrated that gold nanoparticles conjugated to the peptide CLPFFD are useful to destroy the toxic aggregates of β-amyloid, similar to the ones found in the brains of patients with Alzheimer's disease. However, nanoparticles, like many other compounds, have null or very low capacity to cross the blood-brain barrier. In order to devise a strategy to improve drug delivery to the brain, here we introduced the peptide sequence THRPPMWSPVWP into the gold nanoparticle-CLPFFD conjugate. This peptide sequence interacts with the transferrin receptor present in the microvascular endothelial cells of the blood-brain barrier, thus causing an increase in the permeability of the conjugate in brain, as shown by experiments in vitro and in vivo. Our results are highly relevant for the therapeutic applications of gold nanoparticles for molecular surgery in the treatment of neurodegenerative diseases such as Alzheimer's disease.
    Biomaterials 07/2012; 33(29):7194-205. · 8.31 Impact Factor
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    ABSTRACT: Gold nanoparticles (AuNPs) have been extensively used in biological applications because of their biocompatibility, size, and ease of characterization, as well as an extensive knowledge of their surface chemistry. These features make AuNPs readily exploitable for biomedical applications, including drug delivery and novel diagnostic and therapeutic approaches. In a previous work, we studied ex vivo distribution of the conjugate C(AuNP)-LPFFD for its potential uses in the treatment of Alzheimer's disease. In this study, we covalently labeled the conjugate with [(18)F]-fluorobenzoate to study the in vivo distribution of the AuNP by positron emission tomography (PET). After intravenous administration in rat, the highest concentration of the radiolabeled conjugate was found in the bladder and urine with a lower proportion in the intestine, demonstrating progressive accumulation compatible with biliary excretion of the conjugate. The conjugate also accumulated in the liver and spleen. PET imaging allowed us to study the in vivo biodistribution of the AuNPs in a noninvasive and sensitive way using a reduced number of animals. Our results show that AuNPs can be covalently and radioactively labeled for PET biodistribution studies.
    Bioconjugate Chemistry 02/2012; 23(3):399-408. · 4.82 Impact Factor
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    ABSTRACT: The inhibition of aggregation and disaggregation effect of a β‐sheet breaker was evaluated by in situ electrochemistry of the Aβ1–42 peptide. The exposition of 10tyr residue was followed using a carbon nanotubes modified glassy carbon electrode immersed directly in the solution. Both processes were studied at a ratio of Aβ/β‐sheet breaker of 10 µM : 100 µM which is effective in vitro. This approach was compared with Thioflavin‐T‐induced fluorescence, gel electrophoresis and electron microscopy results. The results provide new clues about the disposition of the N‐terminal residue of Aβ in the structure of small aggregates, fibrils and amorphous aggregates and is promising for screening inhibitors of β‐amyloid aggregation.
    Electroanalysis 01/2012; 24(4). · 2.50 Impact Factor
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    ABSTRACT: BACKGROUND & AIMS: Gold nanoparticles (GNPs) have promising applications for drug delivery as well as for the diagnosis and treatment of several pathologies, such as those related to the CNS. However, GNPs are retained in a number of organs, such as the liver and spleen. Owing to their negative charge and/or processes of opsonization, GNPs are retained by the reticuloendothelial system, thereby decreasing their delivery to the brain. It is therefore crucial to modify the nanoparticle surface in order to increase its lipophilicity and reduce its negative charge, thus achieving enhanced delivery to the brain. RESULTS: In this article, we have shown that conjugation of 12 nm GNPs with the amphipathic peptide CLPFFD increases the in vivo penetration of these particles to the rat brain. The C(GNP)-LPFFD conjugates showed a smaller negative charge and a greater hydrophobic character than citrate-capped GNPs of the same size. We administered intraperitoneal injections of citrate GNPs and C(GNP)-LPFFD in rats, and determined the gold content in the tissues by neutron activation. Compared with citrate GNPs, the C(GNP)-LPFFD conjugate improved the delivery to the brain, increasing the concentration of gold by fourfold, while simultaneously reducing its retention by the spleen 1 and 2 h after injection. At 24 h, the conjugate was partially cleared from the brain, and mainly accumulated in the liver. The C(GNP)-LPFFD did not alter the integrity of the blood-brain barrier, and had no effect on cell viability.
    Nanomedicine 08/2010; 5(6):897-913. · 5.26 Impact Factor
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    ABSTRACT: The conformation and charge exposure of peptides attached to colloidal gold nanoparticles (AuNPs) are critical for both the colloidal stability and for the recognition of biological targets in biomedical applications such as diagnostics and therapy. We prepared conjugates of AuNPs and three isomer peptides capable of recognizing toxic aggregates of the amyloid beta protein (Abeta) involved in Alzheimer's disease, namely, CLPFFD-CONH(2) (i0), CDLPFF-CONH(2) (i1), and CLPDFF-CONH(2) (i2), where D is the amino acid aspartic acid that is negatively charged at pH = 7.4. We then studied the effect of peptide sequence on the charge exposure through force spectroscopy measurements. The peptide-AuNPs conjugates were fixed on glass surfaces, and their interactions with peptide-functionalized tips were determined. Our results show a higher density of surface charge in the conjugates of the isomers i0 and i2 and a lower density in i1, which is due to the higher degree of functionalization in the first two compared with the third. However, the charge per molecule of the peptide is higher for i1 with respect to i0 and i2, which could be related to the local conformation that the peptides adopt on the surface. The acid-base behavior of the peptide anchored to the AuNPs is different than expected in aqueous solutions of free peptides, which could be related to the low accessibility of the NH(2)-terminal group belonging to the cysteine that is located near the AuNPs surface. In contrast with other techniques, the fixation of the peptide-AuNPs conjugates to a surface allows for characterization of the local charge exposure of peptides anchored to AuNPs over a wide range of pH.
    Langmuir 07/2010; 26(14):12026-32. · 4.38 Impact Factor
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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. · 4.82 Impact Factor
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    ABSTRACT: This work presents the preparation of copper nanoparticles (CuNPs), using as support, inclusion compounds (ICs) formed by α-cyclodextrin (α-CD) with alkylamines as guests. These ICs provide a suitable environment to anchor and immobilize the nanoparticles, because the functional group of the guest molecule provides outwards from the plane of the IC crystal. The characterization of metal nanoparticles was carried out by transmission electron microscopy (TEM) and UV-visible spectrophotometry.
    Molecular Crystals and Liquid Crystals 05/2010; 521(1):246-252. · 0.49 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. · 2.28 Impact Factor
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    ABSTRACT: Amyloids are a family of self-aggregating proteins implicated in various central nervous system disorders, including Alzheimer's disease (AD). It is thought that prefibrillar soluble forms of amyloid peptides, including oligomers, may be the main pathogenic factor in AD. Herein we describe the fabrication of well-defined, functionalized, monomeric beta-amyloid peptide surfaces for studying protein-protein interactions. We first prepared a nonaggregating analogue of the beta-amyloid peptide and then attached it to a gold surface covered with a self-assembled monolayer (SAM) of alkanethiols. After attachment, the native form of the beta-amyloid peptide (Abeta40) was obtained by surface-level intramolecular O-N migration. The surface was characterized by atomic force microscopy (AFM) and self-assembled monolayer for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (SAMDI-TOF MS). The interaction between the surface-bound Abeta40 and monoclonal anti-Abeta40 antibody was tracked by AFM and chemiluminescence, which revealed that the Abeta40 was attached mainly in its monomeric form and that the protein-protein complex was assembled on the surface. Last, we used a proteomics approach to demonstrate the specificity of the Abeta40-functionalized surface in surface-binding experiments employing serum amyloid P (SAP) and bovine serum albumin (BSA).
    ACS Nano 09/2009; 3(10):3091-7. · 12.03 Impact Factor
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    ABSTRACT: The present study addresses the electrochemical behavior and the analytical applications of six 2-nitrophenylbenzimidazole derivatives with activity against Trypanosoma cruzi. When studied in a wide range of pH, by differential pulse polarography, tast polarography and cyclic voltammetry, these compounds exhibited two irreversible cathodic responses. With analytical purposes, the differential pulse polarography mode was selected, which exhibited adequate analytical parameters of repeatability, reproducibility and selectivity. The percentage of recovery was in all cases over 99%, and the detection and quantitation limits were at the level of 1 x 10(-7)mol L(-1) and 1 x 10(-6)mol L(-1), respectively. In addition, the differential pulse polarography method was successfully applied to study the hydrolytic degradation kinetic of one of the tested compounds. Activation energy, kinetic rate constants at different temperatures and half-life values of such application are reported.
    Talanta 09/2009; 79(3):687-94. · 3.50 Impact Factor

Publication Stats

960 Citations
191.18 Total Impact Points


  • 2005–2014
    • University of Santiago, Chile
      • • Facultad de Ciencia
      • • Departamento de Ingeniería Química
      CiudadSantiago, Santiago, Chile
  • 2008–2012
    • IRB Barcelona Institute for Research in Biomedicine
      • Group of Design, synthesis and structure of peptides and proteins
      Barcino, Catalonia, Spain
  • 2010
    • University of Windsor
      Windsor, Ontario, Canada
  • 2009–2010
    • Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN)
      Caesaraugusta, Aragon, Spain
    • Barcelona Science Park
      Barcino, Catalonia, Spain
  • 2007–2009
    • University of Chile
      • Facultad de Ciencias Químicas y Farmacéuticas
      Santiago, Region Metropolitana de Santiago, Chile
  • 2003–2009
    • Parc de recerca biomedica de barcelona
      Barcino, Catalonia, Spain
  • 2001–2002
    • University of Barcelona
      • Departament de Química Orgànica
      Barcelona, Catalonia, Spain