ABSTRACT
Applications of small-angle scattering (SAS) in structural biology have benefited from continuing developments in instrumentation, tools for data analysis, modeling capabilities, standards for data and model presentation, and data archiving. The interplay of these capabilities has enabled SAS to contribute to advances in structural biology as the field pushes the boundaries in studies of biomolecular complexes and assemblies as large as whole cells, membrane proteins in lipid environments, and dynamic systems on time scales ranging from femtoseconds to hours. This review covers some of the important advances in biomolecular SAS capabilities for structural biology focused on over the last 5 years and presents highlights of recent applications that demonstrate how the technique is exploring new territories.
Subject(s)
Membrane Proteins/chemistry , X-Ray Diffraction/methods , Models, Molecular , Scattering, Small AngleABSTRACT
The level of fine particulate air pollution exposure is positively correlated with the death rate of individuals infected with COVID-19. Monitoring is the first step to prevent fine particulate pollution. The instrument based on light scattering method to detect particle concentration has unparalleled advantages over other instruments due to its rapidity, real-time and low cost. Traditional light scattering instruments are limited by the light absorption and particle properties of particles, and their ability to monitor some particles with strong light absorption is greatly reduced. Moreover, when the measured environment is greatly different from the calibration environment, the measurement results often have large errors. In this research, an instrument is designed to detect the forward scattering of light from small angles of particles. It can monitor the number concentration of particles in the environment in real time in four particle size ranges (PM1, PM2.5, PM4 and PM10) and convert it into the mass concentration of particles. By using the simulated atmospheric smoke box and the standard instrument to conduct a field comparison experiment, the reliability and stability of the measurement results are verified. © 2021 SPIE.
ABSTRACT
Hybrid nanoparticles from lipidic and polymeric components were assembled to serve as vehicles for the transfection of messenger RNA (mRNA) using different portions of the cationic lipid DOTAP (1,2-Dioleoyl-3-trimethylammonium-propane) and the cationic biopolymer protamine as model systems. Two different sequential assembly approaches in comparison with a direct single-step protocol were applied, and molecular organization in correlation with biological activity of the resulting nanoparticle systems was investigated. Differences in the structure of the nanoparticles were revealed by thorough physicochemical characterization including small angle neutron scattering (SANS), small angle X-ray scattering (SAXS), and cryogenic transmission electron microscopy (cryo-TEM). All hybrid systems, combining lipid and polymer, displayed significantly increased transfection in comparison to lipid/mRNA and polymer/mRNA particles alone. For the hybrid nanoparticles, characteristic differences regarding the internal organization, release characteristics, and activity were determined depending on the assembly route. The systems with the highest transfection efficacy were characterized by a heterogenous internal organization, accompanied by facilitated release. Such a system could be best obtained by the single step protocol, starting with a lipid and polymer mixture for nanoparticle formation.