Biodegradable phosphorylcholine copolymer for cardiovascular stent coating.

Phosphorylcholine (PC) based polymer coatings with excellent biocompatibility have shown successful commercialization in drug-eluting stents. However, poor degradability represents a challenge in the application of biodegradable stents. Herein, a biodegradable phosphorylcholine copolymer is developed based on one-step radical ring-opening polymerization (RROP). This copolymer was synthesized by copolymerization of a PC unit, degradable ester (2-methylene-1,3-dioxepane, MDO) unit and non-degradable butyl methacrylate (BMA) unit, which showed ratio controllability by changing the monomer ratio during polymerization. We demonstrated that the copolymer with the ratio of 34% MDO, 19% MPC and 47% BMA could form a stable coating by ultrasonic spray, and showed good blood compatibility, anti-adhesion properties, biodegradability, and rapamycin eluting capacity. In vivo study revealed its promising application as a biodegradable stent coating. This work provides a facile path to add biodegradability into PC based polymers for further bio-applications.

A photodynamic antibacterial spray-coating based on the host-guest immobilization of the photosensitizer methylene blue.

In the "post-antibiotic era", healthcare-associated infection has become a global problem that threatens public health and causes huge economic losses. The development of antibacterial coatings based on non-antibiotic strategies is particularly important as drug-resistant bacteria continue to evolve. Photodynamic coatings are a high potential method to treat bacteria, however, the aggregation of photosensitizers on the coating affects the photodynamic capacity seriously. Herein, a photodynamic coating is developed based on the host-guest interaction between ß-cyclodextrin and the photosensitizer methylene blue (MB). The host-guest interaction avoids aggregation of MB and results in a high singlet oxygen quantum yield. Consequently, efficient photoantibacterial activity towards methicillin-resistant Staphylococcus aureus is achieved by the photodynamic coating with very low MB density (0.53 ± 0.06 µg cm-2).

Thermo-triggered ultrafast self-healing of microporous coating for on-demand encapsulation of biomacromolecules.

Medical coatings cooperated with biomacromolecules can regulate biological events and tissue responses, thus increasing medical implant longevity and providing improved and/or new therapeutic functions. In particular, medical coatings, which can load the correct species and doses of biomacromolecules according to individual diagnoses, will significantly optimize treatment effects and satisfy the rising clinical need of "precision medicine". Herein, we report on a dynamic microporous coating with an ultrafast self-healing property to fulfill the "load-and-play" concept for "precision medicine". A structure-switchable coating based on poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) triblock copolymer network is constructed. The coating can be switched to microporous morphology via a water swelling and freeze-drying process. Then, through a mild thermo-trigger as low as 40 °C, this spongy coating can undergo self-healing to switch back to a pore-free structure within minutes to even 5 s. Based on this dynamic coating, we suggest a simple and versatile method to encapsulate biomacromolecules for surface-mediated delivery. The ultrafast self-healing of the microporous structure enables uniform incorporation of biomacromolecules with an easily achieved high loading of albumin of 16.3 µg/cm2 within 1 min. More importantly, controllable encapsulation can be realized by simple control of the concentration of the loading solution. We further demonstrate that the encapsulated biomacromolecules retained their bioactivity. This work may benefit clinicians with flexibility to provide personalized medical coatings for individual patients during treatment.