Entrapping L. plantarum inside of a pectin-based hydrogel: a living biomaterial for treatment of skin disorders

Skin disorders such as acne vulgaris are common multi-causal skin inflammatory conditions, associated to unregulated local immune responses and an increased presence of opportunistic bacteria on the epithelial tissue. Cutaneous microbiome regulation can be aided by probiotic bacteria, such as lactic acid bacteria, which can help in counteracting the hyperproliferation of opportunistic species by excreting antimicrobial metabolites (e.g. lactic acid and bacteriocins). Probiotics can be encapsulated inside organic or inorganic matrixes, thus fabricating a living material that grants microbial survival and takes advantage of the effects of the valuable metabolites of the microorganisms. By combining the accessibility of an easily applicable patch with the antimicrobial property of lactobacilli, an innovative skin-targeted multi-layer device can be envisioned. This project addresses the development of a living material to be used as the active layer of an envisioned skin-targeted device, with Lactobacillus plantarum entrapped in a pectin-based crosslinked hydrogel, a bio-based, stable and super absorbent polymeric matrix able to retain nutriments and water. The living material fabrication process and crosslinking conditions have been developed and revealed an optimal compatibility between bacteria and the matrix, with optimal entrapping efficiency rates. The fabrication process was optimized to guarantee the probiotic survival up to one month of fridge-storing. Indeed, embedded bacteria are metabolically active once incubated back at mesophilic temperatures producing lactic acid and being able to effectively inhibit the growth of Staphylococcus epidermidis, used as a model opportunistic species of the skin environment. The proposed living material provides an innovative and attractive outlook in the development of a novel multi-layer device for the attenuation of local skin disorders related to cutaneous dysbiosis.