Search results for "nanoparticle"
showing 10 items of 2198 documents
Characterization of Polyorganosiloxane Nanoparticles in Aqueous Dispersion by Asymmetrical Flow Field-Flow Fractionation
2001
The advantages of asymmetrical flow field-flow fractionation (AF-FFF) for the characterization of aqueous dispersions of spherical polyorganosiloxane nanoparticles are discussed. With AF-FFF it was possible to obtain information about the synthesis, which is based on the hydrolysis and condensation of alkylalkoxysilanes in aqueous dispersion, and the average size of the spherical nanoparticles in the complex mixture in the presence of excess surfactant. The results are compared to measurements performed with dynamic light scattering (DLS). The size of the nanoparticles increases as a function of the amount of added monomer. Particles with radii between 2 and 50 nm are observed. If only the …
Covalently Binding of Bovine Serum Albumin to Unsaturated Poly(Globalide-Co-ε-Caprolactone) Nanoparticles by Thiol-Ene Reactions.
2019
When nanoparticles (NPs) are introduced to a biological fluid, different proteins (and other biomolecules) rapidly get adsorbed onto their surface, forming a protein corona capable of giving to the NPs a new "identity" and determine their biological fate. Protein-nanoparticle conjugation can be used in order to promote specific interactions between living systems and nanocarriers. Non-covalent conjugates are less stable and more susceptible to desorption in biological media, which makes the development of engineered nanoparticle surfaces by covalent attachment an interesting topic. In this work, the surface of poly(globalide-co-e-caprolactone) (PGlCL) nanoparticles containing double bonds i…
HPMA-Based Nanoparticles for Fast, Bioorthogonal iEDDA Ligation
2019
Contains fulltext : 216143.pdf (Publisher’s version ) (Open Access) Fast and bioorthogonally reacting nanoparticles are attractive tools for biomedical applications such as tumor pretargeting. In this study, we designed an amphiphilic block copolymer system based on HPMA using different strategies to introduce the highly reactive click units 1,2,4,5-tetrazines (Tz) either at the chain end (Tz-CTA) or statistical into the hydrophobic block. This reactive group undergoes a rapid, bioorthogonal inverse electron-demand Diels-Alder reaction (iEDDA) with trans-cyclooctenes (TCO). Subsequently, this polymer platform was used for the preparation of different Tz-covered nanoparticles, such as micell…
Surface charge, effective charge and dispersion/aggregation properties of nanoparticles
2003
A careful investigation of the relationship between surface properties and colloidal behaviour of nanometric particles in concentrated media has shed some light on the important parameters that must be controlled in order to improve the dispersion of mineral particles. Experimental methods such as rheology and osmometry reveal that the aggregation/dispersion process is not only a matter of electrostatics as stated by classical theories. In practice, the relationship between the surface charge and the state of dispersion is probably much less straightforward than generally assumed by the classical argument stating that the higher the surface charge, the higher the electrostatic repulsion bet…
Functionalization of Liposomes with Hydrophilic Polymers Results in Macrophage Uptake Independent of the Protein Corona
2019
Liposomes are established drug carriers that are employed to transport and deliver hydrophilic drugs in the body. To minimize unspecific cellular uptake, nanocarriers are commonly modified with poly(ethylene glycol) (PEG), which is known to minimize unspecific protein adsorption. However, to date, it has not been studied whether this is an intrinsic and specific property of PEG or if it can be transferred to hyperbranched polyglycerol (hbPG) as well. Additionally, it remains unclear if the reduction of unspecific cell uptake is independent of the “basic” carrier at which a surface functionalization with polymers is usually applied. Therefore, we studied the protein corona of differently fun…
Joining Two Natural Motifs: Catechol-Containing Poly(phosphoester)s.
2017
Numerous catechol-containing polymers, including biodegradable polymers, are currently heavily discussed for modern biomaterials. However, there is no report combining poly(phosphoester)s (PPEs) with catechols. Adhesive PPEs have been prepared via acyclic diene metathesis polymerization. A novel acetal-protected catechol phosphate monomer was homo- and copolymerized with phosphoester comonomers with molecular weights up to 42000 g/mol. Quantitative release of the catechols was achieved by careful hydrolysis of the acetal groups without backbone degradation. Degradation of the PPEs under basic conditions revealed complete and statistical degradation of the phosphotri- to phosphodiesters. In …
HPMA copolymers as surfactants in the preparation of biocompatible nanoparticles for biomedical application.
2012
In this work we describe the application of amphiphilic N-(2-hydroxypropyl)methacrylamide (HPMA)-based copolymers as polymeric surfactants in miniemulsion techniques. HPMA-based copolymers with different ratios of HPMA (hydrophilic) to laurylmethacrylate (LMA; hydrophobic) units were synthesized by RAFT polymerization and postpolymerization modification. The amphiphilic polymers can act as detergents in both the miniemulsion polymerization of styrene and the miniemulsion process in combination with solvent evaporation, which was applied to polystyrene and polylactide. Under optimized conditions, monodisperse colloids can be prepared. The most promising results could be obtained by using the…
Biodegradable pH-Sensitive Poly(ethylene glycol) Nanocarriers for Allergen Encapsulation and Controlled Release
2015
In the last decades, the number of allergic patients has increased dramatically. Allergen-specific immunotherapy (SIT) is the only available cause-oriented therapy so far. SIT reduces the allergic symptoms, but also exhibits some disadvantages; that is, it is a long-lasting procedure and severe side effects like anaphylactic shock can occur. In this work, we introduce a method to encapsulate allergens into nanoparticles to avoid severe side effects during SIT. Degradable nanocarriers combine the advantage of providing a physical barrier between the encapsulated cargo and the biological environment as well as responding to certain local stimuli (like pH) to release their cargo. This work int…
Physicochemical investigation of cobalt?iron cyanide nanoparticles synthesized by a novel solid?solid reaction in confined space
2004
Cobalt–iron cyanide (Cox[Fe(CN)6]) nanoparticles have been synthesized by a novel solid–solid reaction in the confined space of dry sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reversed micelles dispersed in n-heptane. The reaction has been carried out by mixing two dry AOT/n-heptane solutions containing CoCl2 and K4Fe(CN)6 or K3Fe(CN)6 nanoparticles in the micellar core, respectively. By UV-Vis spectroscopy it was ascertained that, after the mixing process, the formation of stable nanoparticles is fast and complete. Microcalorimetric measurements of the thermal effect due to the Cox[Fe(CN)6] nanoparticle formation allowed the determination of the stoichiometric ratio (x) and of the molar e…
FT-IR investigation of the acetamide state in AOT reversed micelles
2003
The state of acetamide nanoparticles encapsulated in the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reversed micelles and dispersed in CCl4 has been investigated by Fourier transform infrared spectroscopy. The analysis of the vibrational spectra reveals even at the higher acetamide to AOT molar ratio some changes of the typical H-bonded structure of solid acetamide ascribable to their small size, confinement effects, and acetamide-AOT head group interactions. The stretching modes of acetamide CO and AOT sulfonate groups indicate unambiguously specific acetamide-AOT head group interactions.