Amorphous structure and crystal stability determine the bioavailability of selenium nanoparticles

Area of Science:

• Environmental Science
• Biochemistry
• Materials Science

Background:

• Microorganisms are key players in selenium biogeochemical cycling.
• Selenium nanoparticles (SeNPs) are often produced by microbial reduction of selenite/selenate.
• SeNPs typically exhibit an amorphous structure but can transform into trigonal allotropes.

Purpose of the Study:

• To investigate the crystal structural stability of chemosynthetic and biogenic SeNPs.
• To understand the factors influencing SeNP structural transitions.
• To determine the impact of SeNP crystal structure on selenium bioavailability.

Main Methods:

• Preparation of chemosynthetic and biogenic SeNPs.
• Assessment of SeNP structural stability under various conditions (lyophilization, washing, laser irradiation, electron beam irradiation).
• Analysis of SeNP structure and surface interactions using advanced techniques.
• Evaluation of SeNP bioavailability in bacteria, yeast, and plants.

Main Results:

• Biogenic SeNPs demonstrated high structural stability in their amorphous form across tested conditions.
• Chemosynthetic SeNPs transformed into a trigonal crystalline structure under similar conditions.
• A core-shell structure was observed in biogenic SeNPs post-irradiation.
• Coordination between Se atoms and surface biomacromolecules in biogenic SeNPs inhibited crystallization.
• Amorphous SeNPs exhibited greater bioavailability compared to crystalline forms.

Conclusions:

• The amorphous structure of biogenic SeNPs, stabilized by surface biomacromolecules, is crucial for selenium bioavailability.
• Understanding SeNP structural dynamics is essential for predicting their environmental fate and biological effects.
• Biogenic SeNPs offer a promising avenue for selenium delivery and management due to their stable amorphous structure and bioavailability.