Abstract：
Photocatalytic nanoparticles offer antimicrobial effects under illumination due to the formation of reactive oxygen species (ROS), capable of degrading bacterial membranes. ROS may, however, also degrade human cell membranes and trigger toxicity. Since antimicrobial peptides (AMPs) may display excellent selectivity between human cells and bacteria, these may offer opportunities to effectively \"target\" nanoparticles to bacterial membranes for increased selectivity. Investigating this, photocatalytic TiO2 nanoparticles (NPs) are coated with the AMP LL-37, and ROS generation is found by C11 -BODIPY to be essentially unaffected after AMP coating. Furthermore, peptide-coated TiO2 NPs retain their positive ζ-potential also after 1-2 h of UV illumination, showing peptide degradation to be sufficiently limited to allow peptide-mediated targeting. In line with this, quartz crystal microbalance measurements show peptide coating to promote membrane binding of TiO2 NPs, particularly so for bacteria-like anionic and cholesterol-void membranes. As a result, membrane degradation during illumination is strongly promoted for such membranes, but not so for mammalian-like membranes. The mechanisms of these effects are elucidated by neutron reflectometry. Analogously, LL-37 coating promoted membrane rupture by TiO2 NPs for Gram-negative and Gram-positive bacteria, but not for human monocytes. These findings demonstrate that AMP coating may selectively boost the antimicrobial effects of photocatalytic NPs.
摘要：
由于形成活性氧（ROS），光催化纳米颗粒在光照下提供抗菌作用。能够降解细菌膜。ROS可能，然而,还会降解人细胞膜并引发毒性。由于抗菌肽（AMP）可能在人类细胞和细菌之间显示出优异的选择性，这些可能会提供机会，有效地\"目标\"纳米粒子到细菌膜增加选择性。调查这个,光催化TiO2纳米颗粒（NP）被AMPLL-37包覆，并且通过C11-BODIPY发现ROS的产生在AMP包覆后基本上不受影响。此外，肽包被的TiO2NP在紫外线照射1-2小时后也保持其正ζ电位，显示肽降解被充分限制以允许肽介导的靶向。与此相符,石英晶体微天平测量显示肽涂层可促进TiO2NP的膜结合，尤其是细菌样阴离子和胆固醇空隙膜。因此,对于这样的膜，在照明过程中的膜降解被强烈促进，但对于哺乳动物样的膜却并非如此。这些效应的机理已通过中子反射仪阐明。类似地,LL-37涂层通过TiO2NPs促进革兰氏阴性和革兰氏阳性细菌的膜破裂，但不是人类单核细胞。这些发现表明AMP涂层可以选择性地增强光催化NP的抗微生物作用。
