Antifouling Properties of Amine-Oxide-Containing Zwitterionic Polymers

Biofouling due to nonspecific proteins or cells on the material surfaces is a major challenge in a range of applications such as biosensors, medical devices, and implants. Even though poly(ethylene glycol) (PEG) has become the most widely used stealth material in medical and pharmaceutical products, the number of reported cases of PEG-triggered rare allergic responses continues to increase in the past decades. Herein, a new type of antifouling material poly(amine oxide) (PAO) has been evaluated as an alternative to overcome nonspecific foulant adsorption and impart comparable biocompatibility. Alkyl-substituted PAO containing diethyl, dibutyl, and dihexyl substituents are prepared, and their solution properties are studied. Photoreactive copolymers containing benzophenone as the photo-cross-linker are prepared by reversible addition-fragmentation chain-transfer polymerization and fully characterized by gel permeation chromatography and dynamic light scattering. Then, these water-soluble polymers are anchored onto a silicon wafer with the aid of UV irradiation. By evaluating the fouling resistance properties of these modified surfaces against various types of foulants, protein adsorption and bacterial attachment assays show that the cross-linked PAO-modified surface can efficiently inhibit biofouling. Furthermore, human blood cell adhesion experiments demonstrate that our PAO polymer could be used as a novel surface modifier for biomedical devices.

Self-Assembly Anchored Cationic Copolymer Interfaces for Applying the Control of Counterion-Induced Bacteria Killing/Release Procedure

In recent years, daily hygiene and disease control issues have received increasing attention, especially the raging epidemics caused by the spread of deadly viruses. The construction of the interface of new polymer materials is focused on, which can provide a cyclic operation process for the killing and releasing of bacteria, and perform repeated regeneration, which is of great significance for the development of advanced medical biomaterials. In order to explore the basic physical phenomena of bacterial attachment and detachment on the polymer material interface by different amine groups, this study plans to synthesize four different butyl methacrylate (BMA)-based cationic copolymers with primary, ternary, and quaternary amine groups, and compare their effects on bactericidal efficiency. Since BMA can generate strong hydrophobic interactions with the benzene ring structure, this study used a polystyrene substrate to realize a self-assembled cationic copolymer interface for controlling the counterion-induced bacterial killing/release process. Furthermore, negatively charged ions are introduced to induce changes in the hydration capability of water molecules and control the subsequent bacterial detachment function. In this study, possible directions to answer and clarify the above concepts are proposed, and there is a basic reference principle that can lead to research work in macromolecular bioscience fields.

Impact of Membrane Modification and Surface Immobilization Techniques on the Hemocompatibility of Hemodialysis Membranes: A Critical Review

Despite significant research efforts, hemodialysis patients have poor survival rates and low quality of life. Ultrafiltration (UF) membranes are the core of hemodialysis treatment, acting as a barrier for metabolic waste removal and supplying vital nutrients. So, developing a durable and suitable membrane that may be employed for therapeutic purposes is crucial. Surface modificationis a useful solution to boostmembrane characteristics like roughness, charge neutrality, wettability, hemocompatibility, and functionality, which are important in dialysis efficiency. The modification techniques can be classified as follows: (i) physical modification techniques (thermal treatment, polishing and grinding, blending, and coating), (ii) chemical modification (chemical methods, ozone treatment, ultraviolet-induced grafting, plasma treatment, high energy radiation, and enzymatic treatment); and (iii) combination methods (physicochemical). Despite the fact that each strategy has its own set of benefits and drawbacks, all of these methods yielded noteworthy outcomes, even if quantifying the enhanced performance is difficult. A hemodialysis membrane with outstanding hydrophilicity and hemocompatibility can be achieved by employing the right surface modification and immobilization technique. Modified membranes pave the way for more advancement in hemodialysis membrane hemocompatibility. Therefore, this critical review focused on the impact of the modification method used on the hemocompatibility of dialysis membranes while covering some possible modifications and basic research beyond clinical applications.

Bio-inspired hemocompatible surface modifications for biomedical applications

When blood first encounters the artificial surface of a medical device, a complex series of biochemical reactions is triggered, potentially resulting in clinical complications such as embolism/occlusion, inflammation, or device failure. Preventing thrombus formation on the surface of blood-contacting devices is crucial for maintaining device functionality and patient safety. As the number of patients reliant on blood-contacting devices continues to grow, minimizing the risk associated with these devices is vital towards lowering healthcare-associated morbidity and mortality. The current standard clinical practice primarily requires the systemic administration of anticoagulants such as heparin, which can result in serious complications such as post-operative bleeding and heparin-induced thrombocytopenia (HIT). Due to these complications, the administration of antithrombotic agents remains one of the leading causes of clinical drug-related deaths. To reduce the side effects spurred by systemic anticoagulation, researchers have been inspired by the hemocompatibility exhibited by natural phenomena, and thus have begun developing medical-grade surfaces which aim to exhibit total hemocompatibility via biomimicry. This review paper aims to address different bio-inspired surface modifications that increase hemocompatibility, discuss the limitations of each method, and explore the future direction for hemocompatible surface research.

Surface PEGylation via Ultrasonic Spray Deposition for the Biofouling Mitigation of Biomedical Interfaces

Air plasma and spray technology are common methods for surface modification. In this study, air plasma is used to generate hydroxyl groups on various material surfaces. Then random copolymers of styrene and ethylene glycol methacrylate (PS-r-PEGMA) are spray-coated to achieve coating densities ranging between 0.1 and 0.6 mg/cm². PS₅₀-r-PEGMA₅₀ led to the best overall antifouling properties, while a coating density of 0.3 mg/cm² was enough to significantly reduce biofouling. This surface modification technique enabled efficient modification of a wide range of materials and biofouling reduction by at least 75% on polymeric surfaces (polystyrene, polyvinylidene fluoride, poly(tetrafluoroethylene), polydimethylsiloxane), metallic surfaces (steel, titanium alloy), or ceramic surface (glass). Applied to the modification of well plate used for blood-typing, this antifouling modification permitted to greatly increase the signal sensitivity (×4).

Dual-responsive zwitterion-modified nanopores：a mesoscopic simulation study

In this work, dissipative particle dynamics simulation was carried out to investigate the intelligent switching effect of nanopores grafted by the zwitterionic polymer brushes poly(carboxybetaine) with excellent antifouling property. The...

Convergent charge interval spacing of zwitterionic 4-vinylpyridine carboxybetaine structures for superior blood-inert regulation in amphiphilic phases

Antifouling materials are indispensable in the biomedical field, but their high hydrophilicity and surface free energy provoke contamination on surfaces under atmospheric conditions, thus limiting their applicability in medical devices. This study proposes a new zwitterionic structure, 4-vinylpyridine carboxybetaine (4VPCB), that results in lower surface free energy and increases biological inertness. In the design of 4VPCB, one to three carbon atoms are inserted between the positive charge and negative charge (carbon space length, CSL) of the pyridyl-containing side chain to adjust hydration with water molecules. The pyridine in the 4VPCB structure provides the hydrophobicity of the zwitterionic functional group, and thus it can have a lower free energy in the gas phase but maintain higher hydrophilicity in the liquid phase environment. Surface plasmon resonance and confocal microscopy were used to analyze the antiprotein adsorption and anti-blood cell adhesion properties of the P4VPCB brush surface. The results showed that the CSL in the P4VPCB structure affected the biological inertness of the surface. The protein adsorption on the surface of P4VPCB2 (CSL= 2) is lower than that on the surfaces of P4VPCB1 (CSL = 1) and P4VPCB3 (CSL = 3), and the optimal resistance to protein adsorption can be reduced to 7.5 ng cm^-2. The surface of P4VPCB2 can also exhibit excellent blood-inert function in the adhesion test with various human blood cells, offering a potential possibility for the future design of a new generation of blood-inert medical materials.

Studies of polypropylene surface modified with novel beta-thiopropionate-based zwitterionic polymeric brush: synthesis, surface characterization, and significantly reduced fouling characteristics evaluation

Creating a surface with anti- or reduced fouling characteristics can lead to a reduction in nonspecific protein adsorption as well as the bacterial adhesion and platelet adhesion/activation that occur as follows. A zwitterionic polymer that consists of both cationic and anionic functionalities have been reported as an effective material to achieve these goals, likely resulted from the strongly-adsorbed hydration layer after being immersed in the physiological environment. In this investigation, a novel beta-thiopropionate-based zwitterionic monomer, 2-ammonio-3-((3-(2-hydroxy-3-(methacryloyloxy)propoxy)-3-oxopropyl)thio)-3-methylbutanoate (DPAMA), was synthesized through a facial process. And then the hydrophobic polypropylene was surface modified with this novel zwitterionic polymer through the surface-initiated atom transfer radical polymerization technique. Surface characterization analyses have been employed to investigate the modified surface properties in each reaction stage. In vitro protein adsorption, bacterial adhesion, and platelet compatibility evaluations have shown the polyDPAMA-modified polypropylene surface has significantly reduced fouling characteristics and good hemocompatibility. Henceforth, this novel zwitterionic polyDPAMA grafting PP and the associated grafting reaction scheme have great potential for future clinical applications.

Zwitterionic shielded polymeric prodrug with folate-targeting and pH responsiveness for drug delivery

Zwitterionic polymers are a class of polymers that acts as both Lewis base and Lewis acid in solution. These polymers not only have excellent properties of hydration, anti-bacterial adhesion, charge reversal and easy chemical modification, but also have characteristics of long-term circulation and suppress nonspecific protein adsorption in vivo. Here, we describe a novel folate-targeted and acid-labile polymeric prodrug under the microenvironment of tumor cells, abbreviated as FA-P(MPC-co-PEGMA-BZ)-g-DOX, which was synthesized via a combination of reversible addition-fragmentation chain transfer (RAFT) copolymerization, Schiff-base reaction, Click chemistry, and a reaction between the amine group of doxorubicin (DOX) and aldehyde functionalities of P(MPC-co-PEGMA-BZ) pendants, wherein MPC and PEGMA-BZ represent 2-(methacryloyloxy)ethyl phosphorylcholine and polyethylene glycol methacrylate ester benzaldehyde, respectively. The polymeric prodrug could self-assemble into nanoparticles in an aqueous solution. The average particle size and morphologies of the prodrug nanoparticles were observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. We also investigated the in vitro drug release behavior and observed rapid prodrug nanoparticle dissociation and drug release under a mildly acidic microenvironment. The methyl thiazolyl tetrazolium (MTT) assay verified that the P(MPC-co-PEGMA-BZ) copolymer possessed good biocompatibility and the FA-P(MPC-co-PEGMA-BZ)-g-DOX prodrug nanoparticles showed higher cellular uptake than those prodrug nanoparticles without the FA moiety. The results of cytotoxicity and the intracellular uptake of non-folate/folate targeted prodrug nanoparticles further confirmed that FA-P(MPC-co-PEGMA-BZ)-g-DOX could be efficiently accumulated and rapidly internalized by HeLa cells due to the strong interaction between multivalent phosphorylcholine (PC) groups and cell membranes. This kind of multifunctional FA-P(MPC-co-PEGMA-BZ)-g-DOX prodrug nanoparticle with combined target-ability and pH responsiveness demonstrates promising potential for cancer chemotherapy.