Advancing SeNP synthesis: Innovative confined environments for enhanced stability and size control

Nanotechnology's exponential growth has spurred a demand for high-quality and safe nanomaterials, prompting increased interest in cost-effective and fast colloidal syntheses that must mitigate their irreversible aggregation, an issue particularly pertaining to spherical selenium nanoparticles (SeNPs), promising materials in a wide array of technological and biological fields. This study presents a novel approach to SeNP synthesis in confined environments developed from the highly biocompatible surfactant sodium oleate (NaOl) and the amino acid l-cysteine as a selenite-reducing agent. l-cysteine@NaOl (C@NaOl) confined environments were modulable as a function of the amino acid and surfactant concentrations and yielded high-quality spherical SeNPs with enhanced stability. This approach enables generating SeNPs even under alkaline conditions and improving up to 3-fold the final SeNP yield compared to other processes. Besides, we introduce a groundbreaking method for determining SeNP size by adapting Mie's scattering theory to metalloid NPs. This innovative technique proves effective for SeNPs in the 40–100 nm range, offering a reliable alternative to conventional sizing methods. These findings provide valuable insights regarding the generation of bio- and eco-compatible confined environments and SeNPs, paving the way for developing safe, cost-effective, and environmentally friendly strategies for their synthesis with broad applications in various scientific and technological domains.