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ABSTRACT: In this study, we report on the design, synthesis, and full characterization of a covalently-linked, triclosan silica-based nanoparticles (T-SNPs), coated with a polyaminated shell (NH(2) -T-SNPs). Various techniques are used to elucidate and rationalize the potential biological mechanism of action of these novel nanoparticles. NH(2) -T-SNPs are found to be potently bactericidal with no detectable lag time for the antimicrobial activity against E. coli and S. aureus. In this context, we also prove that triclosan is the chemical agent that mediated the bactericidal activity of these chemically-modified NPs. The obtained experimental data allows us to pinpoint the actual minimal bactericidal concentrations (MBCs) of triclosan-bound NPs by quantifying intracellular triclosan concentrations. Furthermore, we conduct preliminary cytotoxicity studies, which show that triclosan bound NPs are less cytotoxic (2000 fold) in vitro compared to free-triclosan when tested with various human and mammalian cell lines. Taken together, our results further support the characterization and development of these new nanoscale materials for various biomedical applications.
Advanced healthcare materials. 10/2012;
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ABSTRACT: This paper reports a simple method for the controllable synthesis of highly effective SiO 2 @Pt supported catalysts. Hybrid photoreactive silica nanoparticles (NPs) modified with benzophenone (SiO 2 @BPh) were used as the supporting phase while Pt NPs were used as the catalyst. Monodisperse Pt NPs were homogeneously deposited on the supporting phase with full control of metal loading (from 2.15 to 34.60 wt%) via direct photoreduction of the PtCl 6 2À metal precursor. The catalytic activities of our supported catalysts were evaluated by the reduction reaction of 4-nitrophenol by sodium borohydride. These catalytic activities were found to be much higher than those of unsupported Pt NPs reported in the literature and commercial Pt/C supported catalyst. The facile synthetic method established in this study should largely contribute to the further development of various highly effective supported catalysts.
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ABSTRACT: Functional gold surfaces are of great interest in the field of biosensors, since reactions taking place at such surfaces are easily detected and can be applied in numerous applications. Nanotubes (NTs) have been explored as modifying nanostructuration agents for quartz crystal microbalance (QCM) electrodes. Two goals must be achieved in this study. First, preparation of functional NTs which are able to bind to the gold surface; second, these NTs should have an additional functional group which will bind biological markers. Functional silica nanotubes (SNTs) have great potential in various applications due to their biocompatibility and ability to bind functional groups in a covalent manner using various silica based linkers. Although many publications deal with the introduction of functional groups onto the SNT surface, at present there are no reports in the literature regarding core–shell morphology with a functional polymer shell, which is covalently linked to SNTs. Furthermore, such functional core–shell SNTs can be further modified by other functional groups like amines or thiols by a 2 nd step functionalization. This fact gives rise to an orthogonal nanocomposite (NC) that can be used as the essential modification component of QCM electrodes for the detection of biological markers.
Journal of Materials Chemistry 12/2011; · 5.97 Impact Factor
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ABSTRACT: Antibiotic resistance has prompted the search for new agents that can inhibit bacterial growth. We recently reported on the antimicrobial and antibiofilm activities of nanosized magnesium fluoride (MgF(2)) nanoparticles (NPs) synthesized in ionic liquid using microwave chemistry. In this article, we describe a novel water-based synthesis of MgF(2) NPs using sonochemistry. The sonochemical irradiation of an aqueous solution of [Mg(OAc)(2)⋅(H(2)O)(4)] containing acidic HF as the fluorine ion source afforded crystalline well-shaped spherical MgF(2) NPs that showed much improved antibacterial properties against two common bacterial pathogens (Escherichia coli and Staphylococcus aureus). We were also able to demonstrate that the antimicrobial activity was dependent on the size of the NPs. In addition, using the described sonochemical process, we coated glass surfaces and demonstrated inhibition of bacterial colonization for 7 days. Finally, the antimicrobial activity of MgF(2) NPs against established biofilms was also examined. Taken together our results highlight the potential to further develop the concept of utilizing these metal fluoride NPs as novel antimicrobial and antibiofilm agents. FROM THE CLINICAL EDITOR: In this article, the authors describe a novel aqueous synthesis of magnesium fluoride NPs using sonochemistry. These nanoparticles have improved antibacterial and antibiofilm activity compared to their counterparts with traditional synthesis methods.
Nanomedicine: nanotechnology, biology, and medicine 09/2011; 8(5):702-11. · 5.44 Impact Factor
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ABSTRACT: Nanocomposites (NCs) that are made magnetically responsive in controlled conditions attract continuing interest for their added magnetic properties. In this study, we report on the preparation and full characterization of a multifunctional NC composed of magnetic γ-Fe(2)O(3) nanoparticles (NPs) covalently attached to the surface of polyaminated (polyNH(2)) poly(2,6-di-pyrrol-1-yl-hexanoic acid) (pDPL) nanotubes (NTs). Such a hybrid conducting polymer iron oxide maghemite γ-Fe(2)O(3)@pDPL NC built specifically on covalent bonding has never been reported. The maghemite γ-Fe(2)O(3) NPs were prepared using an innovative ultrasound-assisted Ce(3+) doping process, resulting in polycarboxylation of the NP surface useful for control of aggregation and derivatization of functionality. The second component of the NC, i.e. polyNH(2)-modified pDPL NTs, was prepared from an acid functional pyrrole species followed by amine modification. The resulting innovative γ-Fe(2)O(3)@pDPL NC can be viewed as a multifunctional nanomaterial since it possesses both types of derivatization, i.e. polyCOOH (NPs) and polyNH(2) (NTs) combined with magnetic responsivity.
Nanotechnology 07/2011; 22(28):285604. · 3.98 Impact Factor
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ABSTRACT: The design and fabrication of novel nanosized materials possessing light-sensitive properties has always been the subject of intense activity and interest amongst the scientifi c community. Accordingly, innovative UV-photoreactive silica (SiO 2) nanoparticles emerge as an excellent material candidate for the surface functionalization and nanostructuration of biocompatible polymeric coatings opening a quite wide and generic avenue in this challenging domain. Monodisperse, colloidal silica nanoparticles (NPs) are being widely investigated due to a variety of applications in various fields of chemistry. Many works utilize incorporation of various functional groups to silica NPs for their further modifications. However, at present no benzophenone (BPh) or phenyl azide (PA) containing silica NPs exist. Upon UV irradiation BPh and PA form highly reactive species that react with any organic material. Here we present a convenient method for the preparation of novel hybrid photoreactive silica NPs (denoted as SiO 2 @photoreactive group) prepared by co-condensation of photoreactive organosilanes and tetraethyl orthosilicate (TEOS) to obtain SiO 2 @PA and SiO 2 @BPh NPs. The reactivity of these two types of silica NPs is compared to that of perfluorinated phenyl azide (PFPA) based SiO 2 NPs. The reactivity evaluation is carried out by the reaction of the three types of SiO 2 NPs with highly inert poly(2-chloro-paraxylelene) films. It is found that, in contrast to what is stated in the literature, PA is much more reactive than PFPA, when dealing with solid state photochemical reactions. Next, photoreactive silica NPs on polymer films are used as an intermediate functional phase for a second modification step using silane-based chemistry. A successful incorporation of amine functionality onto silica NPs is achieved by their reaction with 3-aminopropyltriethoxysilane (APTES) and is verified by fluorescence microscopy. This strategy provides a general and versatile route to efficient functionalization of silica by light.
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ABSTRACT: The high-power ultrasonic irradiation of preformed magnetite (Fe(3)O(4)) nanoparticles in the presence of monoelectronic Ce-containing ceric ammonium nitrate [Ce(IV)(NH(4))(2)(NO(3))(6)] oxidant in MeCOMe afforded hydrophilic 50 nm-sized colloidal, highly stable maghemite (gamma-Fe(2)O(3)) nanoparticles. An "inorganic" Ce atom doping of the NP surface has been proposed in order to rationalize the observed nanoparticle antiaggregation phenomenon. Quite importantly, this method did not require the use of any organic ligand and/or polymer for the passivation of the nanoparticle surface.
Journal of the American Chemical Society 09/2010; 132(36):12519-21. · 9.91 Impact Factor
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ABSTRACT: Complex hybrid organic-"multi inorganic" particles SiO2 PDCL-ZrO2 (Ag SiO2) (PDCL = poly(N-dicarbazolyl-lysine)) were synthesized stepwise from silica nanoparticles. First, the zirconia units were synthesized by sol-gel processing and anchored to the polyCOOH poly(dicarbazole-lysine) shell of pre-formed silica particles through metal coordination on residual COOH groups. Investigation of the particle morphology indicated a core-shell structure. A second sol-gel reaction was then carried out at the surface of the SiO2 PDCL-ZrO2 particles using a mixture of alkoxysilanes including an amino-substituted silane capable of chelating silver cations. Once the outer shell made of organically substituted silica was deposited, silver particles were generated by UV treatment, thus leading to an external layer of homogeneously dispersed silver nanoparticles in silica.
Dalton Transactions 10/2008; · 3.84 Impact Factor
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ABSTRACT: The paper discusses the interpretation of electrochemical and spectroelectrochemical measurement of charging and transport of elec-tronic species in conducting polymers, as a function of the polymer potential. The charging is accessible via two independent methods of measuring the chemical capacitance, C l : electrically, by cyclic voltammetry (CV), and optically, by the light absorption. The conductiv-ity, r, is measured by the microband electrode method. We formulate the models of the chemical capacitance for the formation of pola-rons and bipolarons in the presence of Gaussian disorder in the energy levels. This gives rise to the appearance of either one or two broad peaks in CV, depending on the formation energies of the polaron and bipolaron species. We also discuss the interpretation of the dif-fusion coefficient D p and conductivity in the presence of a broad disorder. We find that the relation r = C l D p is generally valid, and application of the generalized Einstein relation allows us to find also the properties of the carrier mobility, u p . A decrease of the mobility at very high carrier densities is expected because the density of states (DOS) is finite, and the transport is limited by the decrease of avail-able empty transport sites. The observation of separate capacitance peaks for polarons and bipolarons is reported in a polydicarbazole based conducting polymer, namely poly[2,6-bis-carbazole-9-yl-hexanoic acid pentafluorophenol ester]. The measured conductivity dis-plays the expected feature, on the basis of the model, of a decrease when the DOS is saturated at high oxidation levels.
12/2007;
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ABSTRACT: Carboxylated pyrrole (Pyr, a index)- and carbazole (Cbz, b index)-containing monomers 6-7a/b and 9a/b have been readily synthesized from the monobenzyl ester of L-glutamic acid and triamine 2 using Clauson-Kaas and amide coupling reactions. In contrast to Pyr-containing compounds 6-7a, and 9a, the three Cbz-containing monomers 6-7b, and 9b have been found electroactive and were successfully electropolymerized on a Pt electrode resulting in the deposition of corresponding insoluble electroconducting polyCOOH polyCbz-films poly(6-7b) and poly(9b).
The Journal of Organic Chemistry 12/2006; 71(24):9139-43. · 4.45 Impact Factor
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ABSTRACT: Novel functional polydipyrrole- and polydicarbazole nanorods have been AAO template-synthesized from COOH-dipyrrole/-dicarbazole monomers using Vapor Deposition and Liquid Phase Polymerizations (VDP and LPP). They were tested as insoluble supports for covalent DNA attachment and hybridization.
Chemical Communications 10/2005; · 6.17 Impact Factor
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ABSTRACT: Novel bis-heterocyclic mono- and dicarboxylated dipyrrole and dicarbazole monomers have been synthesized in a modular manner. Their oxidative polymerization around magnetite nanosized particles has been investigated and optimized toward new magnetic magnetite-polydipyrrole/polydicarbazole nanocomposites (NCs) of a core-shell morphology. These NCs were thoroughly characterized by FT-IR, TGA (Thermal Gravimetric Analysis), low- and high-resolution TEM/HR-TEM microscopies, and Mössbauer spectroscopy along with magnetization studies. Exploiting the versatile COOH chemistry (activation by water-soluble diimides) introduced by the polymeric shell, DNA hybridization experiments have been conducted onto NC surfaces using an efficient blue-colored HRP-based enzymatic screening biological system. Highly parallel NC-supported DNA hybridization experimentations revealed that these NCs presented an interesting potential for DNA-based diagnostic applications.
Journal of the American Chemical Society 09/2005; 127(34):11998-2006. · 9.91 Impact Factor
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ABSTRACT: Magnetically responsive COOH-polydicarbazole-magnetite nanocomposites have been prepared by chemical oxidation of three COOH-dicarbazole monomers and - in the presence of magnetite nanoparticles. These functionalized nanoparticles have been tested for DNA hybridization experiments.
Chemical Communications 04/2004; · 6.17 Impact Factor
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ABSTRACT: An electrochemical impedance analysis of the doping kinetics of polydicarbazole films is reported. Polymer films of varying thickness were analyzed using an impedance model that considers spatially-restricted diffusion of ionic species. The main bulk parameters for diffusion and charge accumulation during doping were determined from fits. These parameters resulted independent of film thickness after considering the experimental error. The equilibrium (bulk) capacitance C0 varies in the range of 100–800 F cm−3. The chemical diffusion coefficient D varies within the range of 10−10 to 10−8 cm2 s−1 and increases as the steady-state potential reaches the oxidation peak potential.
Electrochimica Acta.
