1,720,966 research outputs found
Toward a new generation of nanoparticles for therapy and diagnosis
No full textProgress in utilizing inorganic nanoparticles for biomedical applications has advanced rapidly due to the extensive amount of work done in the synthesis and modification of the materials.1 These nanosized materials provide a robust framework in which two or more components can be incorporated to give multifunctional capabilities. An example can be seen in gold nanomaterials.2 Gold nanoparticles are bioinert, nontoxic, and readily synthesized and functionalized.3 They also provide a multifunctional platform for both therapeutic and diagnostic purposes. Indeed, through proper functionalization, these particles can be engineered to accumulate at illness cells using targeting ligands providing a powerful tool, for example, for gene therapy.4 The biophysico-chemical properties of the vehicle, such as size, charge, surface hydrophilicity, and the nature and density of the ligands on their surface, can all impact the circulating half-life of the particles as well as their biodistribution.
Innovation may be introduced by controlling the surface properties of the monolayer protecting the gold core. Indeed, recently it has been demonstrated that particles coated with a molecularly ordered ligand shell were able to enter cells directly through the membrane without perforating it basing on a novel physical chemistry phenomenon.6 This property is ideal as it provides the particles with minimal if none genotoxicity. Mixed monolayers composed of mixtures of hydrogenated/fluorurated ligands favor the phase segregation and consequently the ordered morphology of the NP surface. 7 In addition, the introduction in the monolayer of perfluorocarbon ligands might enable, for example, the imaging by 19F MRI techniques of the nanoparticles and, consequently, the tracking in vivo of cell fate.
In this communication we will discuss the approaches for the realization of such innovative nanoparticles easy to make, because obtained by self-assembly strategies, but with an unprecedented degree of complexity, with respect to nanotechnology platforms for drug delivery applications know to date, as far as their features is concerned
Aldolase Activity of Serum Albumins
No full textBovine and human serum albumins catalyze the aldol reaction of aromatic aledhyedes and acetone, with saturation kinetics and moderate and opposite enantioselectivity. The reaction occurs at the binding site in domain IIa, and is inhibited by warfarin. Kinetic data are consistent with an enamine mechanism. The activity is conserved in a 103 aminoacid peptide derived from the albumin sequence
Control of the morfology of mixed monolayers protecting gold nanoparticles using perfluoro ligands
No full textRoutes to the preparation of mixed monolayers of fluorinated and hydrogenated alkanethiolates grafted on the surface of gold nanoparticles
Full text linkThe use of binary blends of hydrogenated and fluorinated alkanethiolates represents an interesting approach to the construction of anisotropic hybrid organic–inorganic nanoparticles since the fluorinated and hydrogenated components are expected to self-sort on the nanoparticle surface because of their reciprocal phobicity. These mixed monolayers are therefore strongly non-ideal binary systems. The synthetic routes we explored to achieve mixed monolayer gold nanoparticles displaying hydrogenated and fluorinated ligands clearly show that the final monolayer composition is a non-linear function of the initial reaction mixture. Our data suggest that, under certain geometrical constraints, nucleation and growth of fluorinated domains could be the initial event in the formation of these mixed monolayers. The onset of domain formation depends on the structure of the fluorinated and hydrogenated species. The solubility of the mixed monolayer nanoparticles displayed a marked discontinuity as a function of the monolayer composition. When the fluorinated component content is small, the nanoparticle systems are fully soluble in chloroform, at intermediate content the nanoparticles become soluble in hexane and eventually they become soluble in fluorinated solvents only. The ranges of monolayer compositions in which the solubility transitions are observed depend on the nature of the thiols composing the monolayer
Gold nanoparticles as drug carriers: a contribution to the quest of basic principles for monolayer design
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Flying under the radar. Morphology prediction of the self-assembly of PEG-modified thiolate mixtures on the surface of stealth gold nanoparticles by experiment and multiscale modeling
No full textFluorinated and Charged Hydrogenated Alkanethiolates Grafted on Gold: Expanding the Diversity of Mixed-Monolayer Nanoparticles for Biological Applications
Full text linkLow intrinsic toxicity, high solubility, and stability are important and necessary features of gold nanoparticles to be used in the biomedical field. In this context, charged nanoparticles proved to be very versatile, and among them charged mixed-monolayer gold nanoparticles, displaying monolayers with well-defined morphologies, represent a paradigm. By using mixtures of hydrogenated and fluorinated thiols, the formation of monolayer domains may be brought to an extreme because of the immiscibility of fluorinated and hydrogenated chains. Following this rationale, mixed monolayer gold nanoparticles featuring ammonium, sulfonate, or carboxylic groups on their surface were prepared by using amphiphilic hydrogenated thiols and 1H,1H,2H,2H-perfluoro-alkanethiols. The toxicity of these systems was assessed in HeLa cells and was found to be, in general, low even for the cationic nanoparticles which usually show a high cytotoxicity and is comparable to that of homoligand gold nanoparticles displaying amphiphilic charge neutral hydrogenated or fluorinated thiolates in their monolayer. These properties make the mixed ligand monolayer gold nanoparticles an interesting new candidate for medical application
Self-sorting in mixed fluorinated/hydrogenated assemblies
No full textMixtures of fluorinated and hydrogenated compounds display peculiar properties arising from their mutual phobicity and the same applies to semifluorinated species in which a reciprocal phobicity pattern exists within the same molecule. The interest in assemblies comprising these species stems from the ease in which self-sorting can take place, allowing the preparation of compartmentalised molecular aggregates with unique hydrophobic patterns or surface features. Most importantly, this is the result of molecular properties rather than specifically designed fabrication techniques. This brief overview describes some examples that are instrumental to present the features of fluorinated/hydrogenated supramolecular assemblies in which self-sorting of the dislike units takes place at different length scales. This review is focussed on flat assemblies such as self-assembled monolayers on gold surfaces, Langmuir Blodgett films and on three dimensional assemblies such as micelles, vesicles and nanoparticles
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