Image Printing on the Surface of Anti-Biofouling Zwitterionic Polymer Brushes by Ion Beam Irradiation

Measurement of the Adhesion Force of a Living Sessile Organism on Antifouling Coating Surfaces Prepared with Polysulfobetaine-Grafted Particles

An antifouling polymer brush-like structure was fabricated by a simple and versatile dip-coating method of sulfobetaine containing copolymer-grafted silica nanoparticles (SiNPs) and alkyl diiodide cross-linkers. Surface-initiated atom transfer radical copolymerization of 3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate (MAPS) and N,N-dimethylaminoethyl methacrylate (DMAEMA) was carried out from initiator-immobilized SiNPs to give poly(MAPS-co-DMAEMA)-grafted SiNPs (MAPS/DMAEMA = 9/1, mol/mol) with diameters of 150-170 nm. The SiNP-g-copolymer/2,2,2-trifluoroethanol solution was dip-coated on silicon and glass substrates. Successive treatment with 1,4-diiodobutane in methanol gave a hydrophilic cross-linked coating film for the SiNP-g-copolymer. The cross-linked particle brushes did not peel off from the substrate even after washing with water in an ultrasonic cleaner despite the simple physical absorption of the SiNP-g-copolymer on the substrate surface. The adhesion force of the tentacle of a living barnacle cyprid on a glass surface covered with the cross-linked SiNP-g-copolymer was directly measured by scanning probe microscopy in seawater. The coating film exhibited extremely low adhesion to the cypris larva in the seawater, expecting this to be an effective antifouling property.

Solvent-driven migration of highly polar monomers into hydrophobic PDMS produces a thick graft layer via subsurface initiated ATRP for efficient antibiofouling

Organic solvents that possess affinity towards both polar monomers and hydrophobic PDMS play a “driving” role in the diffusion of polar monomers into the subsurface of the PDMS substrate.

Study of the Interactions of Zwitterions and Carbon Nanotubes by Nonlinear Rheology in an Aqueous Environment

Aqueous nanocomposite solutions of P(NIPAM) and P(NIPAM- co- N-(3-Sulfopropyl)- N-(methacryloxyethyl)- N,N-dimethylammonium betaine), a zwitterionic monomer with carbon nanotubes (CNT) as filler, were synthesized and characterized rheologically. While the influence of P(NIPAM) content and CNT content can be considered to be relatively minor, the introduction of a zwitterionic monomer (Zw) into the polymer leads to clear rheological traces of strong interactions between zwitterionic moieties and surface moieties on the CNTs, namely, a significantly lower nonlinearity limit and a lower modulus at high Zw contents and a higher modulus at intermediate contents due to adsorption of zwitterionic moieties on the CNT surface as well as a significantly lengthened time for the sample to adjust itself to the applied deformation, suggesting that the adsorbed polymer chains need to reorganize themselves significantly to accommodate to the applied strain γ₀.

A novel approach for UV-patterning with binary polymer brushes

A mixed self-assembled monolayer (SAM) of an initiator (3-(2-bromo-2-isobutyryloxy)propyl triethoxysilane) for atom transfer radical polymerization (ATRP) and an agent (6-(triethoxysilyl)hexyl 2-(((methylthio)carbonothioyl)thio)-2-phenylacetate) for reversible addition-fragmentation chain transfer (RAFT) polymerization was constructed on the surface of a silicon wafer or glass plate by a silane coupling reaction. When a UV light at 254nm was irradiated at the mixed SAM through a photomask, the surface density of the bromine atom at the end of BPE in the irradiated region was drastically reduced by UV-driven scission of the BrC bond, as observed by X-ray photoelectron spectroscopy. Consequently, the surface-initiated (SI)-ATRP of 2-ethylhexyl methacrylate (EHMA) was used to easily construct the poly(EHMA) (PEHMA) brush domain. Subsequently, SI-RAFT polymerization of a zwitterionic vinyl monomer, carboxymethyl betaine (CMB), was performed. Using the sequential polymerization, the PCMB and PEHMA brush domains on the solid substrate could be very easily patterned. Patterning proteins and cells with the binary polymer brush is expected because the PCMB brush indicated strong suppression of protein adsorption and cell adhesion, and the PEHMA brush had non-polar properties. This technique is very simple and useful for regulating the shape and size of bio-fouling and anti-biofouling domains on solid surfaces.

Antifouling Stripes Prepared from Clickable Zwitterionic Copolymers

In this study, we have fabricated robust patterned surfaces that contain biocompatible and antifouling stripes, which cause microorganisms to consolidate into bare silicon spaces. Copolymers of methacryloyloxyethyl phosphorylcholine (MPC) and a methacrylate-substituted dihydrolipoic acid (DHLA) were spin-coated onto silicon substrates. The MPC units contributed biocompatibility and antifouling properties, and the DHLA units enabled cross-linking and the formation of robust thin films. Photolithography enabled the formation of 200-μm-wide poly(MPC-DHLA) stripped patterns that were characterized using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and rhodamine 6G staining. Regardless of the spacing between poly(MPC-DHLA) stripes (10, 50, or 100 μm), Escherichia coli rapidly adhered to the bare silicon gaps that lacked the copolymer, confirming the antifouling nature of MPC. Overall, this work provides a surface modification strategy for generating alternating biofouling and nonfouling surface structures that are potentially applicable for researchers studying cell biology, drug screening, and biosensor technology.

Zwitterionic Polyhydroxybutyrate Electrospun Fibrous Membranes with a Compromise of Bioinert Control and Tissue-Cell Growth

We present a method for surface modification by thermal-evaporation self-assembling of poly(3-hydroxybutyrate) (PHB) fibrous membranes with a copolymer of hydrophobic octadecyl acrylate repeat units and hydrophilic zwitterionic 4-vinylpyridine blocks, zP(4VP-r-ODA), in view of controlling biofoulant-fiber interactions. PHB is of interest as a material for bioscaffolding, but its disadvantage is its hydrophobicity, which leads to unwanted interactions with proteins, blood cells, or bacteria. Surface modification of electrospun PHB fibers addresses this issue because the hydrophilicity of the membranes is improved, leading to a significant reduction in bovine serum albumin (92%), lysozyme (73%), and fibrinogen (50%) adsorption. From a coating density of 0.78 mg/cm², no bacteria interacted with the fibers, and from 1.13 mg/cm², excellent hemocompatibility of membranes was measured from thrombocytes, erythrocytes, leukocytes, and whole blood attachment tests. Additionally, HT-1080 fibroblasts were observed to develop in contact with the fibers after 3-7 days of incubation (cell density up to 329 ± 16 cells/mm²), suggesting that zP(4VP-r-ODA) provides an adequate humid environment for their growth. Providing an effective control of the surface chemistry and of the coating density, the association of PHB and zP(4VP-r-ODA) can promote the growth of fibroblasts, still maintaining resistance to unwanted biofoulants, and appears to be a promising composite material for tissue engineering.

Biodegradable shape memory polymers functionalized with anti-biofouling interpenetrating polymer networks

A novel type of shape memory polyurethane (SMPU) with high mechanical properties and biodegradability was constructed using a lactone copolymer (poly(ε-caprolactone-co-γ-butyrolactone), PCLBL), a diol- or triol-based chain extender (1,5-pentanediol, glycerol and 2-amino-2-hydroxymethyl-1,3-propanediol) and a diisocyanate cross-linker (1,6-hexamethylene diisocyanate).