Institute of Condensed Matter and Nanosciences , Université catholique de Louvain , Croix du Sud 1/L7.04.02 , Louvain-la-Neuve 1348 , Belgium.
David H. Koch Institute for Integrative Cancer Research , Massachusetts Institute of Technology , 500 Main Street , Cambridge , Massachusetts 02139 , United States.
ACS Appl Mater Interfaces. 2018 May 16;10(19):16250-16259. doi: 10.1021/acsami.8b01988. Epub 2018 May 3.
Commensal skin bacteria such as Staphylococcus epidermidis are currently being considered as possible components in skin-care and skin-health products. However, considering the potentially adverse effects of commensal skin bacteria if left free to proliferate, it is crucial to develop methodologies that are capable of maintaining bacteria viability while controlling their proliferation. Here, we encapsulate S. epidermidis in shells of increasing thickness using layer-by-layer assembly, with either a pair of synthetic polyelectrolytes or a pair of oppositely charged polysaccharides. We study the viability of the cells and their delay of growth depending on the composition of the shell, its thickness, the charge of the last deposited layer, and the degree of aggregation of the bacteria which is varied using different coating procedures-among which is a new scalable process that easily leads to large amounts of nonaggregated bacteria. We demonstrate that the growth of bacteria is not controlled by the mechanical properties of the shell but by the bacteriostatic effect of the polyelectrolyte complex, which depends on the shell thickness and charge of its outmost layer, and involves the diffusion of unpaired amine sites through the shell. The lag times of growth are sufficient to prevent proliferation for daily topical applications.
共生皮肤细菌，如表皮葡萄球菌，目前被认为是皮肤护理和皮肤保健产品的可能成分。然而，考虑到共生皮肤细菌如果不受控制地增殖可能产生的潜在不利影响，开发能够在控制其增殖的同时保持细菌活力的方法至关重要。在这里，我们使用逐层组装的方法，用一对合成聚合物电解质或一对带相反电荷的多糖来包裹具有不同厚度的表皮葡萄球菌。我们研究了细胞的活力及其生长的延迟，这取决于壳的组成、厚度、最后沉积层的电荷以及细菌的聚集程度，细菌的聚集程度可以通过不同的涂层程序来改变——其中包括一种新的可扩展过程，很容易得到大量非聚集的细菌。我们证明，细菌的生长不是由壳的机械性能控制的，而是由聚电解质复合物的抑菌作用控制的，抑菌作用取决于壳的厚度和最外层的电荷，并涉及未配对的胺基位点通过壳的扩散。生长的滞后时间足以防止日常局部应用的增殖。
