Efficient characterization of nanodrugs X ray small angle scattering method

Nano-drugs have more unique advantages than traditional drugs, but nano-drugs have difficulties in drug research and development for injectable and non-injectable drug delivery due to the chemical, physical and biological instability of their biomolecules and their absorption characteristics, therefore, the study of nano carriers to carry macromolecule drugs to enhance their absorption, stabilization, and targeting has a good development prospect, and it also needs to be comprehensively, scientifically, and reasonably characterize the nano-drugs. At the same time, it is also necessary to comprehensively, scientifically and rationally characterize nanomedicines, develop appropriate quality control indicators for drugs and establish corresponding detection methods.

Current nanomedicines fall into two main categories: brand new nanomedicines and nanocarriers.

The new nanomedicine refers to nanoparticles directly processed from raw drugs, and nanocarriers refer to various nanoparticles that dissolve or disperse drugs, such as nanoliposomes, polymer nanocapsules, nanospheres, polymer micelles, etc., which are traditional molecular drugs that are improved using nanotechnology. The analysis of nanodrugs focuses on the characterization of structure and properties, such as particle size and size distribution, dispersion, dispersion stability, surface electrical properties, surface composition and valence, surface free energy and structure, etc. Understanding the structure and properties of nanodrugs is beneficial for exploring their biological properties and pharmacological pharmacodynamic mechanisms.

Small-angle X-ray scattering (SAXS) is an effective method to determine the particle size distribution of nanoparticles by utilizing the small-angle X-ray scattering effect, and its related theories, experimental techniques and data processing methods have been matured, and international technical specifications and national standards have been formulated. It can generally determine the particle size distribution of ultrafine particles with a particle scale of 1~300 nm, and can also measure the particle size of inorganic and organic solvents as well as biological macromolecules; however, it is not suitable for particles with micropores and mixed particles composed of different materials.

The principle of small angle X-ray scattering method is: when a beam of very fine X-rays through the nanopowder layer, after the scattering of electrons within the particles, it will be dispersed in the original incident X-ray beam around the 0 ~ 2 small angle region, and its scattering intensity distribution is related to the particle size distribution. If the particle size distribution in the specimen is assumed to be continuous, a continuous distribution function can be used to express its particle size distribution.