Superhydrophobic surfaces have been reported to reduce bacterial adhesion, but interactions between bacterial media and solid surfaces at the interface have rarely been associated with the solid area fraction (f) from the Cassie–Baxter wetting state. This study aimed to investigate the effective surface area for bacterial adhesion by analyzing the solid area fraction of surfaces where the bacterial medium is in contact with a solid surface. Also, the self-cleaning ability of the superhydrophobic surface against adhered bacteria was examined. The influences of roughness, surface energy, entrapped air, and surface charge of substrate materials on bacterial adhesion were examined, and the critical surface characteristics that are conducive to reducing Escherichia coli adherence to polymeric surfaces were determined. Moderate hydrophobicity with water contact angle of about 90° produced the highest level of bacterial adhesion. Entrapped air at the interface of superhydrophobic surfaces interfered with the direct contact of bacteria to solid surfaces, leading to less bacterial adhesion. The superhydrophobic surface with a reduced solid area fraction displayed self-cleaning ability, where initially-adhered bacteria were removed by washing. The superhydrophilic substrate with negative zeta potential exhibited limited bacterial binding, due to the reduced hydrophobic interaction and possible repulsive interaction between bacteria and surface. The findings of this study can be utilized for an effective surface design to circumvent bacterial adhesion as an alternative solution to using antibiotics.
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机译：据报道，超疏水表面可减少细菌的粘附，但细菌介质与界面固体表面之间的相互作用很少与卡西-巴克斯特润湿状态下的固体面积分数（ f ）相关。这项研究旨在通过分析细菌介质与固体表面接触的表面的固体部分来研究细菌粘附的有效表面积。另外，检查了超疏水表面对附着的细菌的自清洁能力。研究了粗糙度，表面能，截留的空气和基质材料的表面电荷对细菌粘附的影响，并确定了有助于降低大肠杆菌对聚合物表面粘附的关键表面特征。与水接触角约为90°的中等疏水性可产生最高水平的细菌粘附。超疏水表面界面处截留的空气会干扰细菌与固体表面的直接接触，从而减少细菌的粘附。具有减小的固体面积分数的超疏水表面表现出自清洁能力，其中通过洗涤除去最初粘附的细菌。具有负ζ电势的超亲水底物由于减少的疏水相互作用以及细菌与表面之间可能的排斥相互作用而显示出有限的细菌结合。这项研究的发现可用于有效的表面设计，以规避细菌粘附，作为使用抗生素的替代解决方案。
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