Summary: The reaction of hydrazine with ethyl glycolate results in 1,2‐bisglycoylhydrazine, a monomer that was used for the lipase‐catalyzed synthesis of biodegradable poly(ester hydrazide)s. The polymers derived from the hydrazide‐containing monomer and vinyl‐activated adipic, suberic, and sebacic acid, respectively, showed low melting temperatures of 136 to 141 °C and are thermally stable up to 300 °C. The aliphatic poly(ester hydrazide)s (PEHs) are highly crystalline, as proven by polarization microscopy and atomic force microscopy. Further, the PEHs represent the first described biodegradable poly(hydrazide)s. They degrade in the presence of lipase at 37 °C within a few weeks.
A successful drug delivery system must overcome complex biological barriers. For particles injected into the blood, one of the first and most critical barriers pertains to blood stability to circulate through the human body. To effectively design drug delivery vehicles, interactions between the particles and blood, as well as the aggregation behavior, must be understood. This work presents a method to analyze particle size and aggregation in blood plasma using a commercially available nanoparticle tracking analysis (NTA) system. As a model system, fluorescently labeled polystyrene nanoparticles are incubated in goat blood plasma and analyzed using NTA. The particles incubated in plasma are found to have a protein corona that is larger than what has been observed by dynamic light scattering (DLS) in diluted plasma. Particles that are decorated with a PEG layer are also found to have large protein coronas in undiluted plasma. Because NTA is based on a unique visualization method, large multicomponent aggregates could be observed and quantified in a manner not feasible with other techniques. PEGylation of the particles is found to decrease the multicomponent aggregation from 1000 ± 200 particles for unmodified to 200 ± 30 particles for 1K PEGylated per 1 × 105 total particles. 相似文献
Light shining through wall experiments (in the optical as well as in the microwave regime) are a powerful tool to search for light particles coupled very weakly to photons such as axions or extra hidden sector photons. Resonant regeneration, where a resonant cavity is employed to enhance the regeneration rate of photons, is one of the most promising techniques to improve the sensitivity of the next generation of experiments. However, doubts have been voiced if such methods work at very low regeneration rates where on average the cavity contains less than one photon. In this Letter we report on a demonstration experiment using a microwave cavity driven with extremely low power, to show that resonant amplification works also in this regime. In accordance with standard quantum mechanics this is a demonstration that interference also works at the level of less than one quantum. As an additional benefit this experiment shows that thermal photons inside the cavity cause no adverse effects. 相似文献