Search results for " Polyethylene glycol"
showing 10 items of 40 documents
Gold nanostar–polymer hybrids for siRNA delivery: Polymer design towards colloidal stability and in vitro studies on breast cancer cells
2017
To overcome the low bioavailability of siRNA (small interfering RNA) and to improve their transfection efficiency, the use of non-viral delivery carriers is today a feasible approach to transform the discovery of these incredibly potent and versatile drugs into clinical practice. Polymer-modified gold nanoconstructs (AuNCs) are currently viewed as efficient and safe intracellular delivery carriers for siRNA, as they have the possibility to conjugate the ability to stably entrap and deliver siRNAs inside cells with the advantages of gold nanoparticles, which can act as theranostic agents and radiotherapy enhancers through laser-induced hyperthermia. In this study, AuNCs were prepared by coat…
Solvation of a probe molecule by fluid supercooled water in a hydrogel at 200 K
2008
By combining electron paramagnetic resonance (EPR) measurements on a nitroxide probe and differential scanning calorimetry (DSC), we demonstrate existence of liquid supercooled water in a silica hydrogel with high hydration level down to temperatures of at least 198 K. Besides the major fraction of liquid supercooled water, a minor fraction crystallizes at about 236 K during cooling and melts at 246 K during heating. The liquid domains are of sufficient size to solvate the nearly spherical paramagnetic probe molecule TEMPO with a diameter of about 6 angstrom. Analysis of EPR spectra provides the rotational correlation time of the probe that is further used to compare the viscosity of the su…
Morphogenetically active scaffold for osteochondral repair (Polyphosphate/alginate/N,O-carboxymethyl chitosan)
2016
Here we describe a novel bioinspired hydrogel material that can be hardened with calcium ions to yield a scaffold material with viscoelastic properties matching those of cartilage. This material consists of a negatively charged biopolymer triplet, composed of morphogenetically active natural inorganic polyphosphate (polyP), along with the likewise biocompatible natural polymers N,O-carboxymethyl chitosan (N,O-CMC) and alginate. The porosity of the hardened scaffold material obtained after calcium exposure can be adjusted by varying the pre-processing conditions. Various compression tests were applied to determine the local (nanoindentation) and bulk mechanical properties (tensile/compressio…
Effect of bioglass on growth and biomineralization of SaOS-2 cells in hydrogel after 3D cell bioprinting.
2014
We investigated the effect of bioglass (bioactive glass) on growth and mineralization of bone-related SaOS-2 cells, encapsulated into a printable and biodegradable alginate/gelatine hydrogel. The hydrogel was supplemented either with polyphosphate (polyP), administered as polyP • Ca2+-complex, or silica, or as biosilica that had been enzymatically prepared from ortho-silicate by silicatein. These hydrogels, together with SaOS-2 cells, were bioprinted to computer-designed scaffolds. The results revealed that bioglass (nano)particles, with a size of 55 nm and a molar ratio of SiO2 : CaO : P2O5 of 55 : 40 : 5, did not affect the growth of the encapsulated cells. If silica, biosilica, or polyP …
Oxygen Transmissibility of Piggyback Systems With Conventional Soft and Silicone Hydrogel Contact Lenses
2006
To investigate the apparent oxygen transmissibility of various piggyback systems using conventional and silicone hydrogel soft contact lenses of different water content and permeability, rigid poly(methyl methacrylate), and rigid gas-permeable lenses of medium, high, and ultrahigh oxygen permeability. The aim of the study was to establish which material (rigid or hydrogel) is more representative of the resulting oxygen performance of piggyback systems. METHODS: The apparent oxygen transmissibility of 66 piggyback systems was measured with an electrochemical method. Eighteen of these combinations involved the use of silicone hydrogel contact lenses currently available. One hyperpermeable rig…
Comparing analytical methods to detect SARS-CoV-2 in wastewater
2021
Wastewater based epidemiology (WBE) has emerged as a reliable strategy to assess the coronavirus disease 2019 (COVID-19) pandemic. Recent publications suggest that SARS-CoV-2 detection in wastewater is technically feasible; however, many different protocols are available and most of the methods applied have not been properly validated. To this end, different procedures to concentrate and extract inactivated SARS-CoV-2 and surrogates were initially evaluated. Urban wastewater seeded with gamma-irradiated SARS-CoV-2, porcine epidemic diarrhea virus (PEDV), and mengovirus (MgV) was used to test the concentration efficiency of an aluminum-based adsorption-precipitation method and a polyethylene…
Effects of confinement on insulin amyloid fibrils formation.
2006
Insulin, a 51-residue protein universally used in diabetes treatment, is known to produce amyloid fibrils at high temperature and acidic conditions. As for other amyloidogenic proteins, the mechanisms leading to nucleation and growth of insulin fibrils are still poorly understood. We here report a study of the fibrillation process for insulin confined in a suitable polymeric hydrogel, with the aim of ascertain the effects of a reduced protein mobility on the various phases of the process. The results indicate that, with respect to standard aqueous solutions, the fibrillation process is considerably slowed down at moderately high concentrations and entirely suppressed at low concentration. M…
Material properties of various intraocular lenses in an experimental study.
2002
<i>Introduction:</i> With the recent introduction of small-incision cataract surgery, requirements for intraocular lens (IOL) flexibility, strength and hydrophilicity have rapidly evolved. The IOL surface, however, remains a critical factor influencing uveal biocompatibility. <i>Purpose:</i> To objectively quantify factors of material properties of various IOLs using contact angle measurements, differential scanning calorimetry, dynamic-mechanical measurements and scanning electron microscopy. <i>Material and Methods:</i> In our study, 17 currently available IOLs were investigated using contact angle measurements to assess hydrophilicity and biocompatibil…
Impact of Safety-Related Dose Reductions or Discontinuations on Sustained Virologic Response in HCV-Infected Patients: Results from the GUARD-C Cohor…
2015
Background: Despite the introduction of direct-acting antiviral agents for chronic hepatitis C virus (HCV) infection, peginterferon alfa/ribavirin remains relevant in many resource-constrained settings. The non-randomized GUARD-C cohort investigated baseline predictors of safety-related dose reductions or discontinuations (sr-RD) and their impact on sustained virologic response (SVR) in patients receiving peginterferon alfa/ribavirin in routine practice. Methods: A total of 3181 HCV-mono-infected treatment-naive patients were assigned to 24 or 48 weeks of peginterferon alfa/ribavirin by their physician. Patients were categorized by time-to-first sr-RD (Week 4/12). Detailed analyses of the i…
Dielectric Relaxations in Confined Hydrated Myoglobin
2009
In this work we report the results of a broadband dielectric spectroscopy study on the dynamics of a globular protein, myoglobin, in confined geometry, i.e. encapsulated in a porous silica matrix, at low hydration levels, where about only one or two water layers surround the proteins. In order to highlight the specific effect of confinement in the silica host, we compared this system with hydrated myoglobin powders at the same hydration levels. The comparison between the data relative to the two different systems indicates that geometrical confinement within the silica matrix plays a crucial role in protein-water dielectric relaxations, the effect of sol-gel encapsulation being essentially …