A Bio-Redox Dynamic Pickering Emulsion from Nature to Nature

The biosafety issue of Pickering emulsions has gradually become public. It is shown that the particles that make up Pickering emulsions, previously thought to be non-physiologically toxic, may also pose a potential threat to human life and health, as well as to ecosystems, due to their inherent emulsifying capacity. Hence, the principle of "from nature to nature" is proposed, which refers to emulsifiers that are of natural origin and can be metabolized by natural biological processes to eliminate their emulsifying ability. A feasible pathway by which the natural small molecule, thioctic acid, is exploited for the preparation of Pickering emulsions is also presented. The strategy of calcium ion-induced aggregation and ring-opening polymerization of sodium thioctate is utilized for the preparation of particulate emulsifiers, thus forming stable O/W-type Pickering emulsions. Benefiting from the antioxidant property of the thioctic acid moiety and the transdermal capacity of the emulsion itself, it combines protection of the bioactive substance with transdermal delivery. Furthermore, the particulate emulsifiers that are prepared, abundantly enriched with dynamic disulfide bonds, can be integrated into the natural metabolic pathway, specifically by being reduced through the involved glutathione, thereby facilitating their natural degradation and effectively mitigating any potential biological hazards.