Superhydrophilic membrane with photo-Fenton self-cleaning property for effective microalgae anti-fouling

Mussel-Inspired In Situ Photodynamic Antibacterial Coating for Postoperative Management of Artificial Corneas

Artificial corneal (AC) implants offer hope to millions with corneal blindness, including 5 million in China. Titanium is one of the materials commonly used in the fabrication of artificial corneal scaffolders because of its light texture, high mechanical properties, and high biosafety. However, postoperative bacterial infections, especially from Pseudomonas aeruginosa and Staphylococcus aureus (S. aureus), remain a significant challenge due to the bioinert nature of titanium materials, leading to high infection rates. In this study, we introduce an innovative in situ photodynamic coating technology designed to manage postoperative infections in artificial corneas. Inspired by mussel adhesive proteins, this coating employs a composite of APTES-TA formed by Schiff base and Michael addition reactions between 3-aminopropyltriethoxysilane (APTES) and tannic acid (TA), integrated with the bacterial targeting capabilities of 4-carboxyphenylboronic acid (CPBA) and the photo-Fenton activity of FeOOH (iron(III) hydroxide). The design of the AC@APTES-TA-CPBA-FeOOH coating leverages the dynamic boronate ester bonds, which interact specifically with bacteria in tears, effectively capturing them on the surface of the artificial cornea. The coating exhibits a photocatalytic Fenton-like effect, which confers it with an exceptional bactericidal efficiency of over 99% in vitro. Furthermore, it demonstrates excellent protective functionality for mouse corneas in vivo experiments.

Generalized Multifunctional Coating Strategies Based on Polyphenol-Amine-Inspired Chemistry and Layer-by-Layer Deposition for Blood Contact Catheters

Blood-contacting catheters play a pivotal role in contemporary medical treatments, particularly in the management of cardiovascular diseases. However, these catheters exhibit inappropriate wettability and lack antimicrobial characteristics, which often lead to catheter-related infections and thrombosis. Therefore, there is an urgent need for blood contact catheters with antimicrobial and anticoagulant properties. In this study, we employed tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) to create a stable hydrophilic coating under mild conditions. Heparin (Hep) and poly(lysine) (PL) were then modified on the TA-APTES coating surface using the layer-by-layer (LBL) technique to create a superhydrophilic TA/APTES/(LBL)4 coating on silicone rubber (SR) catheters. Leveraging the superhydrophilic nature of this coating, it can be effectively applied to blood-contacting catheters to impart antibacterial, antiprotein adsorption, and anticoagulant properties. Due to Hep's anticoagulant attributes, the activated partial thromboplastin time and thrombin time tests conducted on SR/TA-APTES/(LBL)4 catheters revealed remarkable extensions of 276 and 103%, respectively, when compared to uncoated commercial SR catheters. Furthermore, the synergistic interaction between PL and TA serves to enhance the resistance of SR/TA-APTES/(LBL)4 catheters against bacterial adherence, reducing it by up to 99.9% compared to uncoated commercial SR catheters. Remarkably, the SR/TA-APTES/(LBL)4 catheter exhibits good biocompatibility with human umbilical vein endothelial cells in culture, positioning it as a promising solution to address the current challenges associated with blood-contact catheters.

Bioinspired N-Oxide-Based Zwitterionic Polymer Brushes for Robust Fouling-Resistant Surfaces

Fouling-resistant surfaces are needed for various environmental applications. Inspired by superhydrophilic N-oxide-based osmolytes in saltwater fish, we demonstrate the use of a trimethylamine N-oxide (TMAO) analogue for constructing fouling-resistant surfaces. The readily synthesized N-oxide monomer of methacrylamide is grafted to filtration membrane surfaces by surface-initiated atom transfer radical polymerization (SI-ATRP). Successful grafting of the amine N-oxide brush layer as confirmed by material characterization endows the surface with increased hydrophilicity, reduced charge, and decreased roughness. Notably, the introduction of the N-oxide layer does not compromise transport properties, i.e., water permeability and water-salt selectivity. Moreover, the modified membrane exhibits improved antifouling properties with a lower flux decline (32.1%) and greater fouling reversibility (18.55%) than the control sample (45.4% flux decline and 3.26% fouling reversibility). We further evaluate foulant-membrane interaction using surface plasmon resonance (SPR) to relate the reduced fouling tendency to the synergic effects of surface characteristic changes after amine N-oxide modification. Our results demonstrate the promise and potential of the N-oxide-based polymer brushes for the design of fouling resistance surfaces for a variety of emerging environmental applications.