Colloids
Dotaz
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sv.
svazky : ilustrace ; 27 cm
- MeSH
- albuminy farmakologie terapeutické užití MeSH
- deriváty hydroxyethylového škrobu ekonomika farmakologie terapeutické užití MeSH
- koloidy * aplikace a dávkování farmakologie terapeutické užití MeSH
- lidé MeSH
- náklady na zdravotní péči MeSH
- sepse * ekonomika farmakoterapie terapie MeSH
- Check Tag
- lidé MeSH
Gold nanoparticles represent nanosized colloidal entities with high relevance for both basic and applied research. When gold nanoparticles are functionalized with polymer-molecule ligands, hybrid nanoparticles emerge whose interactions with the environment are controlled by the polymer coating layer: Colloidal stability and structure formation on the single particle level as well as at the supracolloidal scale can be enabled and engineered by tailoring the composition and architecture of this polymer coating. These possibilities in controlling structure formation may lead to synergistic and/or emergent functional properties of such hybrid colloidal systems. Eventually, the responsivity of the polymer coating to external triggers also enables the formation of hybrid supracolloidal systems with specific dynamic properties. This review provides an overview of fundamentals and recent developments in this vibrant domain of materials science.
Heterogeneous iron species at the mineral/water interface are important catalysts for the generation of reactive oxygen species at circumneutral pH. One significant pathway leading to the formation of such species arises from deposition of dissolved iron onto mineral colloids due to changes in redox conditions. This study investigates the catalytic properties of Fe impregnated on silica, alumina, and titania nanoparticles (as prototypical mineral colloids). Fe impregnation was carried out by immersing the mineral nanoparticles in dilute Fe(II) or Fe(III) solutions at pH 6 and 3, respectively, in an aerobic environment. The uptake of iron per unit surface area follows the order of nTiO2 > nAl2O3 > nSiO2 for both types of Fe precursors. Impregnation of mineral particles in Fe(II) solutions results in predominantly Fe(III) species due to efficient surface-mediated oxidation. The catalytic activity of the impregnated solids to produce hydroxyl radical (·OH) from H2O2 decomposition was evaluated using benzoic acid as a probe compound under dark conditions. Invariably, the rates of benzoic acid oxidation with different Fe-laden particles increase with the surface density of Fe until a critical density above which the catalytic activity approaches a plateau, suggesting active Fe species are formed predominantly at low surface loadings. The critical surface density of Fe varies with the mineral substrate as well as the aqueous Fe precursor. Fe impregnated on TiO2 exhibits markedly higher activity than its Al2O3 and SiO2 counterparts. The speciation of interfacial Fe is analyzed with diffuse reflectance UV-vis analysis and interpretation of the data in the context of benzoic oxidation rates suggests that the surface activity of the solids for ·OH generation correlates strongly with the isolated (i.e., mononuclear) Fe species. Therefore, iron dispersed on mineral colloids is a significant form of reactive iron surfaces in the aquatic environment.
- MeSH
- hydroxylový radikál chemie MeSH
- katalýza MeSH
- koloidy chemie MeSH
- minerály chemie MeSH
- nanočástice MeSH
- oxid hlinitý chemie MeSH
- oxid křemičitý chemie MeSH
- oxidace-redukce MeSH
- peroxid vodíku chemie MeSH
- roztoky chemie MeSH
- titan chemie MeSH
- voda chemie MeSH
- železité sloučeniny chemie MeSH
- železo chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
PURPOSE OF REVIEW: To highlight some of the recent key issues surrounding crystalloid and colloid fluid management of critically ill patients. RECENT FINDINGS: Significant developments have been made in the understanding of ionic balance of fluids and their effects on acid-base, the role of hydration and overhydration, alkalinization of fluids in patients at high risk for contrast induced nephropathy, and finally the role of colloids in acute kidney injury. SUMMARY: Despite hydration remaining a key principle in fluid management in many patients, volume overload is of considerable concern. Recent evidence also suggests that balanced electrolyte formulations are preferable to saline-based formulations in a variety of clinical settings. Furthermore, alkalinization of fluids is protective in the setting of contrast-induced nephropathy. Oncotic load appears to be the most important factor in acute kidney injury associated with colloid fluid therapy.
- Klíčová slova
- koloidní a krystaloidní roztoky, intravaskulární tekutiny,
- MeSH
- akutní poškození ledvin etiologie MeSH
- isotonické roztoky škodlivé účinky MeSH
- koloidy škodlivé účinky MeSH
- kritický stav MeSH
- ledviny účinky léků zranění MeSH
- lidé MeSH
- tekutinová terapie škodlivé účinky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
Leachates collected at two (active and closed) municipal solid waste (MSW) landfills were examined for colloids and particles by transmission electron microscopy, energy dispersive spectrometry, selected area electron diffraction and for the chemical compositions of the filtrates after the filtration to 0.1 µm and ultrafiltration to 1 kDa (~ 1 nm). Six groups of colloids/particles in the range 5 nm to 5 µm were determined (in decreasing order of abundance): carbonates, phyllosilicates (clay minerals and micas), quartz, Fe-oxides, organics and others (salts, phosphates). Inorganic colloids/particles in leachates from the active landfill predominantly consist of calcite (CaCO(3)) and minor clay minerals and quartz (SiO(2)). The colloids/particles in the leachates from the closed landfill consist of all the observed groups with dominant phyllosilicates. Whereas calcite, Fe-oxides and phosphates can precipitate directly from the leachates, phyllosilicates and quartz are more probably either derived from the waste or formed by erosion of the geological environment of the landfill. Low amounts of organic colloids/particles were observed, indicating the predominance of organic molecules in the 'truly dissolved' fraction (fulvic compounds). Especially newly formed calcite colloids forming particles of 500 nm and stacking in larger aggregates can bind trace inorganic contaminants (metals/metalloids) and immobilize them in landfill environments.
The properties of materials at the nanoscale open up new methodologies for engineering prospective materials usable in high-end applications. The preparation of composite materials with a high content of an active component on their surface is one of the current challenges of materials engineering. This concept significantly increases the efficiency of heterogeneous processes moderated by the active component, typically in biological applications, catalysis, or drug delivery. Here we introduce a general approach, based on laser-induced optomechanical processing of silver colloids, for the preparation of polymer surfaces highly enriched with silver nanoparticles (AgNPs). As a result, the AgNPs are firmly immobilized in a thin surface layer without the use of any other chemical mediators. We have shown that our approach is applicable to a broad spectrum of polymer foils, regardless of whether they absorb laser light or not. However, if the laser radiation is absorbed, it is possible to transform smooth surface morphology of the polymer into a roughened one with a higher specific surface area. Analyses of the release of silver from the polymer surface together with antibacterial tests suggested that these materials could be suitable candidates in the fight against nosocomial infections and could inhibit the formation of biofilms with a long-term effect.
Crystalloids, artificial and natural colloids have been opposed as representing different strategies for shock resuscitation, but it may be relevant to distinguish fluids based on their oncotic characteristics. This study assessed the risk of renal adverse events in patients with shock resuscitated using hypo-oncotic colloids, artificial hyperoncotic colloids, hyperoncotic albumin or crystalloids, according to physician's choice. PARTICIPANTS AND SETTING: International prospective cohort study including 1,013 ICU patients needing fluid resuscitation for shock. Patients suffering from cirrhosis or receiving plasma were excluded. MEASUREMENTS AND RESULTS: Influence of different types of colloids and crystalloids on the occurrence of renal events (twofold increase in creatinine or need for dialysis) and mortality was assessed using multivariate analyses and propensity score. Statistical adjustment was based on severity at the time of resuscitation, risks factor for renal failure, and on variables influencing physicians' preferences regarding fluids. A renal event occurred in 17% of patients. After adjustment on potential confounding factors and on propensity score for the use of hyperoncotic colloids, the use of artificial hyperoncotic colloids [OR: 2.48 (1.24-4.97)] and hyperoncotic albumin [OR: 5.99 (2.75-13.08)] was significantly associated with occurrence of renal event. Overall ICU mortality was 27.1%. The use of hyperoncotic albumin was associated with an increased risk of ICU death [OR: 2.79 (1.42-5.47)]. CONCLUSIONS: This study suggests that harmful effects on renal function and outcome of hyperoncotic colloids may exist. Although an improper usage of these compounds and confounding factors cannot be ruled out, their use should be regarded with caution, especially because suitable alternatives exist
- MeSH
- albuminy škodlivé účinky MeSH
- dospělí MeSH
- incidence MeSH
- isotonické roztoky škodlivé účinky MeSH
- jednotky intenzivní péče MeSH
- koloidy škodlivé účinky MeSH
- lidé středního věku MeSH
- lidé MeSH
- nemoci ledvin chemicky indukované mortalita MeSH
- odds ratio MeSH
- prospektivní studie MeSH
- rehydratační roztoky škodlivé účinky MeSH
- riziko MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- šok terapie MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- Geografické názvy
- Evropa MeSH
Well-defined gold nanoparticles (AuNPs) are accessible via simple synthetic methods, and their surface chemistry stands as a key factor in determining applications in the biomedical field. While macromolecules featuring amino groups are already known to successfully mediate the formation of stable gold colloids in one-pot, two-reactant, no workup reactions in aqueous media, we herein report the discovery that, under mild reaction temperatures, polymers of outstanding biomedical interest not only can play the simultaneous role of reducing and capping agent but also lead to particulate systems with unique features. From a library of samples that included branched polyethylenimine (BPEI), poly-(l-lysine) (PLL), bovine serum albumin (BSA), poly-(2-methyl-2-oxazoline) (PMeOx), poly-(N-(2-hydroxypropyl) methacrylamide) (PHPMA), and amine-functionalized poly-(N-(2-hydroxypropyl)-methacrylamide-co-N-(3-aminopropyl)-methacrylamide) P-(HPMA-co-APMA), we found that PHPMA end-functionalized with nitrile motifs generate spherical and stable AuNPs@PHPMA of very small size (diameter of ∼2.4 nm), as underlined by imaging experiments. Cell viability experiments indicated exceptionally good biocompatibility up to very high numerical particle concentrations as compared to the other systems. The reduced size imparted to the AuNPs@PHPMA outstanding catalytic properties (no induction time and high reaction rate constant for the hydrogenation of p-nitrophenol) and antimicrobial activity (total antibacterial activity against Escherichia coli and dose-dependent antibacterial activity against Staphylococcus aureus). The introduction of primary amine groups (13.4 mol %) of higher nucleophilicity known to work better for AuNP synthesis makes these unique features disappear, as evidenced for P-(HPMA-co-APMA). The other systems yielded 6-28 nm particles whose properties reflected both the size of the metallic core and chemical nature and conformation of the capping agent. These findings point to novel applications of PHPMA polymers worthy of further development, especially in light of their excellent water solubility and biocompatibility.
- Publikační typ
- časopisecké články MeSH
