Herein, we developed a nanocomposite membrane with synergistic photodynamic therapy and photothermal therapy antibacterial effects, triggered by a single near-infrared (NIR) light illumination. First, upconversion nanoparticles (UCNPs) with a hierarchical structure (UCNPs@TiO2) were synthesized, which use NaYF4:Yb,Tm nanorods as the core and TiO2 nanoparticles as the outer shell. Then, nanosized graphene oxide (GO), as a photothermal agent, was doped into UCNPs@TiO2 core–shell nanoparticles to obtain UCNPs@TiO2@GO. Afterward, the mixture of UCNPs@TiO2@GO in poly­(vinylidene) fluoride (PVDF) was applied for electrospinning to generate the nanocomposite membrane (UTG-PVDF). Generation of reactive oxygen species (ROS) and changes of temperature triggered by NIR action were both investigated to evaluate the photodynamic and photothermal properties. Upon a single NIR light (980 nm) irradiation for 5 min, the nanocomposite membrane could simultaneously generate ROS and moderate temperature rise, triggering synergistic antibacterial effects against both Gram-positive and -negative bacteria, which are hard to be achieved by an individual photodynamic or photothermal nanocomposite membrane. Additionally, the as-prepared membrane can effectively restrain the inflammatory reaction and accelerate wound healing, thus exhibiting great potentials in treating infectious complications in wound healing progress.

Bacteria-responsive surfaces popularly exert their smart antibacterial activities by bacteria-triggered delivery of antibacterial agents; however, the antibacterial agents should be additionally reloaded for the renewal of these surfaces. Herein, a reversible, nonleaching bacteria-responsive antibacterial surface is prepared by taking advantage of a hierarchical polymer brush architecture. In this hierarchical surface, a pH-responsive poly(methacrylic acid) (PMAA) outer layer serves as an actuator modulating the surface behavior on demand, while antimicrobial peptides (AMP) are covalently immobilized on the inner layer. The PMAA hydration layer renders the hierarchical surface resistant to initial bacterial attachment and biocompatible under physiological conditions. When bacteria colonize the surface, the bacteria-triggered acidification allows the outermost PMAA chains to collapse, therefore exposing the underlying bactericidal AMP to on-demand kill bacteria. In addition, the dead bacteria can be released once the PMAA chains resume their hydrophilicity because of the environmental pH increase. The functionality of the nonleaching surface is reversible without additional reloading of the antibacterial agents. This approach provides a new methodology for the development of smart surfaces in a variety of practical biomedical applications.

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No abstract

Infection and thrombosis associated with medical implants cause significant morbidity and mortality worldwide. As we know, current technologies to prevent infection and thrombosis may cause severe side effects. To overcome these complications without using antimicrobial and anticoagulant drugs, we attempt to prepare a liquid-infused poly(styrene-b-isobutylene-b-styrene) (SIBS) microfiber coating, which can be directly coated onto medical devices. Notably, the SIBS microfiber was fabricated through solution blow spinning. Compared to electrospinning, the solution blow spinning method is faster and less expensive, and it is easy to spray fibers onto different targets. The lubricating liquids then wick into and strongly adhere the microfiber coating. These slippery coatings can effectively suppress blood cell adhesion, reduce hemolysis, and inhibit blood coagulation in vitro. In addition, Pseudomonas aeruginosa (P. aeruginosa) on the lubricant infused coatings slides readily, and no visible residue is left after tilting. We furthermore confirm that the lubricants have no effects on bacterial growth. The slippery coatings are also not cytotoxic to L929 cells. This liquid-infused SIBS microfiber coating could reduce the infection and thrombosis of medical devices, thus benefiting human health.

In this article, a facile approach to fabricate a biofunctional polypropylene nonwoven fabric membrane (PP NWF) with a switchable surface from antibacterial property to hemocompatibility is presented. In the first step, a cationic carboxybetaine ester monomer, [(2-(methacryboxy) ethyl)]-N,N-dimethylamino-ethylammonium bromide, methyl ester (CABA-1-ester) was synthesized. Subsequently, this monomer was introduced on the PP NWF surface via plasma pretreatment and a UV-induced graft polymerization technique. Finally, a switchable surface from antibacterial property to hemocompatibility was easily realized by hydrolysis of poly(CABA-1-ester) moieties on the PP NWF surface under mild conditions. Surface hydrolysis behaviors under different pH conditions were investigated. These PP NWFs grafted with poly(CABA-1-ester) segments can cause significant suppression of S. aureus proliferation; after hydrolysis, these surfaces covered by poly[(2-(methacryloxy) ethyl)] carboxybetaine (poly(CABA)) chains exhibited obvious reduction in protein adsorption and platelet adhesion, and remarkably enhanced antithrombotic properties. This strategy demonstrated that a switchable PP NWF surface from antibacterial property to hemocompatibility was easily developed by plasma pretreatment and UV-induced surface graft polymerization and that this surface may become an attractive platform for a range of biomedical applications.

Unlike conventional poly(N-isopropylacrylamide) (PNIPAM)-based surfaces switching from bactericidal activity to bacterial repellency upon decreasing temperature, we developed a hierarchical polymer architecture, which could maintain bactericidal activities at room temperature while presenting bacterial repellency at physiological temperature. In this architecture, a thermoresponsive bactericidal upper layer consisting of PNIPAM-based copolymer and vancomycin (Van) moieties was built on an antifouling poly(sulfobetaine methacrylate) (PSBMA) bottom layer via sequential surface-initiated photoiniferter-mediated polymerization. At room temperature below the lower critical solution temperature (LCST), the PNIPAM-based upper layer was stretchable, facilitating contact killing of bacteria by Van. At physiological temperature (above the LCST), the PNIPAM-based layer collapsed, thus leading to the burial of Van and exposure of bottom PSBMA brushes, finally displaying notable performances in bacterial inhibition, dead bacteria detachment, and biocompatibility, simultaneously. Our strategy provides a novel pathway in the rational design of temperature-sensitive switchable surfaces, which shows great advantages in the real-world infection-resistant applications.

Pathogenic bacterial contamination is at the root of many persistent and chronic bacterial infections. Synergistic superhydrophobic surfaces functionalized with a cationic antimicrobial agent (e.g., quaternary ammonium components) show promising antimicrobial efficacies, but are inherently contradictory in simultaneously maintaining excellent surface liquid repellency and bactericidal activity due to the compromised low surface energy stemming from the introduced hydrophilic biocides. Herein, we present a synergistic antibacterial cotton textile with superhydrophobic bacterial repellency and photodynamic bactericidal activity for both Staphylococcus aureus and Escherichia coli. The modified cotton textile was constructed by integrating tunable micro/nanoscale roughness, hydrophobic photosensitizer chlorin e6, and surface perfluorination. The triple-scale structured superhydrophobic surfaces exhibited ≲90% reductions in both waterborne and airborne bacterial adhesions. Subsequently, after being exposed to visible light for 45 min, the synergistic surface demonstrated complete inactivation (100% killing) against residual bacterial cells via photodynamic bactericidal capacities. Moreover, the triple-scale structured superhydrophobic surface displayed totally suppressed whole blood adhesion, suggesting potential in preventing plenty of undesirable biomedical forms of contamination. This synergistically antibacterial surface not only improves the antibacterial efficiency but also leads to long-lasting antimicrobial performance, each of which is highly desirable in combating bacterial infections.