Green synthesis of selenium submicron particles with lemon peel extract for high-performance polylactic acid -based food packaging films

The adoption of polylactic acid (PLA), a promising biodegradable alternative to petroleum-based cling films, is constrained by its poor water vapor barrier, lack of antimicrobial activity, and inadequate fresh-keeping functionality. To address these challenges, this study introduces a green and sustainable approach for synthesizing antibacterial selenium submicron particles (SeSPs) using lemon peel extract-a readily available agricultural by-product-as both reducing and stabilizing agent. High-performance liquid chromatography coupled with time-of-flight mass spectrometry (HPLC-TOF-MS2) was employed to identify the major bioactive compounds in the lemon peel extract, providing critical insights into the reduction and stabilization mechanism of selenium ions. The green synthesis conditions for SeSPs were systematically optimized through a series of characterization techniques, confirming their successful preparation and structural properties. Subsequently, the SeSPs integrated into a PLA matrix using polyethylene glycol (PEG) as toughening agent to develop multifunctional composite films. The results demonstrated that SeSPs incorporation significantly enhanced the mechanical strength, water vapor barrier performance, and oxygen impermeability of the PLA films, while also endowing them with potent antibacterial activity against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), achieving inhibition rates exceeding 99%. Fresh-keeping experiments conducted on fresh-cut honeydew melon further demonstrated that the SeSPs/PLA composite film effectively maintained fruit firmness, color, and overall quality, thereby extending shelf life. This work not only offers a biodegradable and high-performance food cling film but also provides mechanistic insights into the formation and stabilization of SeSPs, highlighting the potential of agricultural by-products in sustainable nanotechnology.