Surface hydrolysis-anchored eugenol self-polishing marine antifouling coating

Macrophage-Inspired marine antifouling coating with dynamic surfaces based on regulation of dynamic covalent bonds

Macrophages can kill bacteria and viruses by releasing free radicals, which provides a possible approach to construct antifouling coatings with dynamic surfaces that release free radicals if the breaking of dynamic covalent bonds is precisely regulated. Herein, inspired by the defensive behavior of macrophages of releasing free radicals to kill bacteria and viruses, a marine antifouling coating composed of polyurethane incorporating dimethylglyoxime (PUx-DMG) is prepared by precise regulation of dynamic oxime-urethane covalent bonds. The obtained alkyl radical (R·) derived from the cleavage of the oxime-urethane bonds manages to effectively suppress the attachment of marine biofouling. Moreover, the intrinsic dynamic surface makes it difficult for biofouling to adhere and ultimately achieves sustainable antifouling property. Notably, the PU50-DMG coating not only presents efficient antibacterial and antialgae properties, but also prevents macroorganisms from settling in the sea for up to 4 months. This provides a pioneer broad-spectrum strategy to explore the marine antifouling coatings.

Preparation and antifouling performance of tin-free self-polishing antifouling coatings based on side-chain suspended indole derivative structural resins

Tin-free self-polishing antifouling coatings have the highest market share since organotin self-polishing antifouling coatings have been banned. However, its high dependence on cuprous oxide was found to have caused potential harm to the environment, making it necessary to improve the functionality of the resin. In this paper, a zinc acrylate resin with side chain hanging indole derivative structure was prepared by using N-(1H-5-bromoindole-3-methylene) (BIAM) with good biological activity as functional monomer. The functional resin with good antifouling performance was selected by antibacterial and algae inhibition experiments. The results showed that when the BIAM content was 9 %, the inhibition rates of the resin on E. coli and Prymnesium parvum reached 98 % and 90 %, respectively. Tin-free self-polishing antifouling coatings were prepared using the above resins as film-forming materials. The anti-protein adsorption performance and antifouling performance of the coating were tested by anti-protein adsorption experiment and real sea hanging plate experiment. The results showed that the coating containing indole derivative structure had good anti-protein adsorption performance and antifouling performance, and the higher the BIAM content, the better the anti-protein adsorption performance and marine antifouling performance.

Recent advances of multifunctional zwitterionic polymers for biomedical application

Zwitterionic polymers possess equal total positive and negative charges in the repeating units, making them electrically neutral overall. This unique property results in superhydrophilicity, which makes the zwitterionic polymers highly effective in resisting protein adsorption, thus endowing the drug carriers with long blood circulation time, inhibiting thrombus formation on biomedical devices in contact with blood, and ensuring the good sensitivity of sensors in biomedical application. Moreover, zwitterionic polymers have tumor-targeting ability and pH-responsiveness, rendering them ideal candidates for antitumor drug delivery. Additionally, the high ionic conductivity of zwitterionic polymers makes them an important raw material for ionic skin. Zwitterionic polymers exhibit remarkable resistance to bacterial adsorption and growth, proving their suitability in a wide range of biomedical applications such as ophthalmic applications, and wound dressings. In this paper, we provide an in-depth analysis of the different structures and characteristics of zwitterionic polymers and highlight their unique qualities and suitability for biomedical applications. Furthermore, we discuss the limitations and challenges that must be overcome to realize the full potential of zwitterionic polymers and present an optimistic perspective for zwitterionic polymers in the biomedical fields. STATEMENT OF SIGNIFICANCE: Zwitterionic polymers have a series of excellent properties such as super hydrophilicity, anti-protein adsorption, antibacterial ability and good ionic conductivity. However, biomedical applications of multifunctional zwitterionic polymers are still a major field to be explored. This review focuses on the design and application of zwitterionic polymers-based nanosystems for targeted and responsive delivery of antitumor drugs and cancer diagnostic agents. Moreover, the use of zwitterionic polymers in various biomedical applications such as biomedical devices in contact with blood, biosensors, ionic skin, ophthalmic applications and wound dressings is comprehensively described. We discuss current results and future challenges for a better understanding of multifunctional zwitterionic polymers for biomedical applications.

Silicone-modified polyurea-interpenetrating polymer network fouling release coatings with excellent wear resistance property tailored to regulations

The invasion of alien species via marine organisms attaching to the surfaces of ship hulls is a growing problem. A number of countries have introduced corresponding regulations to combat ship biofouling. One effective way to solve this problem is to apply a fouling release coating with excellent wear resistance. In this study, a silicone-modified polyaspartic ester polyurea was synthesized by a simultaneous crosslinking polymerization. Polyaspartic ester polyurea is employed to form a tightly cross-linked network with excellent toughness and outstanding adhesion, while polydimethylsiloxane is used to form a relatively soft cross-linked network with low surface energy and surface elasticity modulus. Polyurea and silicone molecular chain lock onto each other to form interpenetrating polymer network (IPN) through their respective polymerization systems and cross-linking processes. The synergy between silicone and polyurea provides excellent mechanical properties as well as fouling release performance through the locking mechanism. This study provides a promising and universal strategy for the development of fouling release coatings with excellent wear resistance.

Flexible Poly(vinyl chloride) with Durable Antibiofouling Property via Blending Star-Shaped Amphiphilic Poly(ε-caprolactone)-block-poly(methacryloxyethyl sulfobetaine)

Flexible poly(vinyl chloride) (PVC) plastics have been widely used in medical devices, but the preparation of antibiofouling flexible PVC materials that can maintain their antibiofouling performance when suffering deformation is still a challenge. In this work, we synthesized a series of amphiphilic star-shaped three-arm block copolymers SPCL-b-PSB, consisting of hydrophobic inner blocks poly(ε-caprolactone) (PCL) and hydrophilic outer blocks poly(methacryloxyethyl sulfobetaine) (PSB). Then, flexible PVC films were prepared by blending SPCL-b-PSB with PVC and plasticizer. Benefiting from the specific star-shaped topological structure of SPCL-b-PSB, hydrophilic PSB blocks of the copolymer could efficiently migrate to the surface of the film via annealing treatment, which give the film surface excellent hydrophilicity, while the latch-like entanglements between hydrophobic PCL blocks and PVC give the hydrophilic surface excellent stability. Antibiofouling properties of the blended films were investigated. The optimized blended film could reduce ∼94% of bovine serum albumin adsorption, ∼ 87% of lysozyme adsorption, and ∼89% of platelet adhesion and resist bacterial adhesion effectively. What is more, the blended films could maintain their antibiofouling performance when suffering stretching, rubbing, or bending. More than 86% of bovine serum albumin adsorption could be reduced, even when the film was stretched by 50%. This work provides a new strategy for the preparation of durable antibiofouling flexible plastics.

Anthropogenic Microparticles in Sea-Surface Microlayer in Osaka Bay, Japan

The abundance, distribution, and composition of microparticles (MPs) in the sea-surface microlayer (S-SML, less than 100 μm of sea surface in this experiment) and in bulk water (1 m under the sea surface) were investigated to evaluate the pollution level of MPs in Osaka Bay in Japan. Both seawater fractions were collected at eight sites including ship navigation routes, the coastal area, and the center of Osaka Bay for 2021-2023. MPs were filtered for four size ranges (10-53, 53-125, 125-500, and >500 μm) and then digested with H2O2. MPs' abundance was microscopically assessed; and polymer types of MPs were identified by a Fourier transform infrared spectrometer (FTIR). For the 22 collections performed along eight sites, the average MPs' abundance was 903 ± 921 items/kg for S-SML, while for the 25 collections performed along the same sites, the average MPs' abundance was 55.9 ± 40.4 items/kg for bulk water, respectively. MPs in both S-SML and bulk water exhibited their highest abundance along the navigation routes. The smallest MPs (10-53 μm) accounted for 81.2% and for 62.2% of all MPs in S-SML and in bulk water among all sites, respectively. Polymethyl methacrylate (PMMA) was the major type of MPs identified while minor ones were polyethylene, polyesters, polystyrene, polypropylene, polyvinyl chloride, polyamide, etc. PMMA comprised 95.1% of total MPs in S-SML and 45.6% of total MPs in bulk water. In addition, PMMA accounted for 96.6% in S-SML and 49.5% in bulk water for the smallest MP category (10-53 μm). It can be assumed that the MP sources were marine paints-primarily APPs (antifouling paint particles)-as well as land coatings. Sea pollution due to microparticles from ship vessels should be given proper attention.