The solution behavior originating from molecular characteristics of synthetic macromolecules plays a pivotal role in many areas, in particular the life sciences. This situation necessitates the use of complementary hydrodynamic analytical methods as the only means for a complete structural understanding of any macromolecule in solution. To this end, we present a combined hydrodynamic approach for studying in-house prepared, low dispersity poly(ethylene glycols)s (PEGs), also known as poly(ethylene oxide)s (PEOs) depending on the classification used, synthesized from varying initiation sites by the living anionic ring opening polymerization. The series of linear PEGs in the molar mass range of only a few thousand to 50 000 g mol have been studied in detail via viscometry and sedimentation-diffusion analysis by analytical ultracentrifugation. The obtained estimations for intrinsic viscosity, diffusion coefficients, and sedimentation coefficients of the macromolecules in the solution-based analysis clearly showed self-consistency of the followed hydrodynamic approach. This self-consistency is underpinned by appropriate and physically sound values of hydrodynamic invariants, indicating adequate values of derived absolute molar masses. The classical scaling relations of Kuhn-Mark-Houwink-Sakurada of all molar-mass dependent hydrodynamic estimates show linear trends, allowing for interrelation of all parametric macromolecular characteristics. Differences among these are ascribed to the observation of α-end and chain-length dependent solvation of the macromolecules, identified from viscometric studies. This important information allows for analytical tracing of variations of scaling relationships and a physically sound estimation of hydrodynamic characteristics. The demonstrated self-sufficient methodology paves an important way for a complete structural understanding and potential replacement of pharmaceutically relevant PEGs by alternative macromolecules offering a suite of similar or tractably distinct physicochemical properties.
An optical technique for the parallel manipulation of nanoscale structures with molecular resolution is presented. Bioconjugated metal nanoparticles are thereby positioned at the location of interest, such as, e.g., certain DNA sequences along metaphase chromosomes, prior to pulsed laser light irradiation of the whole sample. The nanoparticles are designed to absorb the introduced energy highly efficiently, in that way acting as nanoantenna. As result of the interaction, structural changes of the sample with subwavelength dimensions and nanoscale precision are observed at the location of the particles. The process leading to the nanolocalized destruction is caused by particle ablation as well as thermal damage of the surrounding material.
Butyrate has suppressing-agent activities in human colon cells by inhibiting two survival factors, namely hGSTT1 and cell growth, with LT97 more sensitive than HT29. These findings indicate that butyrate formation in the gut lumen of humans could be protective by reducing survival of transformed colon cells.
Reactive polymersomes represent av ersatile artificial cargo carrier system that can facilitate an immediate release in response to aspecific stimulus.The herein presented oxidation-sensitive polymersomes feature at ime-delayed release mechanism in an oxidative environment, whichc an be precisely adjusted by either tuning the membrane thickness or partial pre-oxidation. These polymeric vesicles are conveniently prepared by PISA allowing the straightforwarda nd effective in situ encapsulation of cargo molecules,asshown for dyes and enzymes.Kinetic studies revealed acritical degree of oxidation causing the destabilization of the membrane,w hile no release of the cargo is observed beforehand. The encapsulation of glucose oxidase directly transforms these polymersomes into glucose-sensitive vesicles,a ss mall molecules including sugars can passively penetrate their membrane. Considering the ease of preparation, these polymersomes represent av ersatile platform for the confinement and burst release of cargo molecules after ap recisely adjustable time span in the presence of specific triggers,s uch as H 2 O 2 or glucose.
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