Controlled adsorption of bovine serum albumin on poly(acrylonitrile)-based zwitterionic membranes

Novel Thermosensitive-co-Zwitterionic Sulfobetaine Gels for Metal Ion Removal: Synthesis and Characterization

Zwitterionic betaine polymers are promising adsorbents for the removal of heavy metal ions from industrial effluents. Although the presence of both negative and positively charged groups imparts them the ability to simultaneously remove cations and anions, intra- and/or inter-chain interactions can significantly reduce their adsorption efficiencies. Therefore, in this study, novel gels based on crosslinked co-polymers of thermosensitive N-isopropylacrylamide (NIPAAM) and zwitterionic sulfobetaine N,N-dimethylacrylamido propyl ammonium propane sulfonate (DMAAPS) were synthesized, characterized, and evaluated for ion removal. Fourier-transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) analyses confirmed the success of the co-polymerization of NIPAAM and DMAAPS to form poly(NIPAAM-co-DMAAPS). The phase transition temperature of the co-polymer increased with increasing DMAAPS content in the co-polymer, indicating temperature-dependent amphiphilic behavior, as evidenced by contact angle measurements. The ion adsorption analyses of the poly(NIPAAM-co-DMAAPS) gels indicated that co-polymerization increased the molecular distance and weakened the interaction between the DMAAPS-charged groups (SO3- and N+), thereby increasing the ion adsorption. The results confirmed that, with a low concentration of DMAAPS in the co-polymer gels (~10%), the maximum amount of Cr3+ ions adsorbed onto the gel was ~58.49% of the sulfonate content in the gel.

Constructing safe and durable antibacterial textile surfaces using a robust graft-to strategy via covalent bond formation

Recently zwitterionic materials have been widely applied in the biomedical and bioengineering fields due to their excellent biocompatibility. Inspired by these, this study presents a graft-to strategy via covalent bond formation to fabricate safe and durable antibacterial textile surfaces. A novel zwitterionic sulfobetaine containing triazine reactive group was specifically designed and synthesized. MTT assay showed that it had no obvious cytotoxicity to human skin HaCaT cells as verified by ca. 89.9% relative viability at a rather high concentration of 0.8 mg·mL⁻¹. In the evaluation for its skin sensitization, the maximum score for symptoms of erythema and edema in all tests were 0 in all observation periods. The sulfobetaine had a hydrophilic nature and the hydrophilicity of the textiles was enhanced by 43.9% when it was covalently grafted onto the textiles. Moreover, the textiles grafted with the reactive sulfobetaine exhibited durable antibacterial activities, which was verified by the fact that they showed antibacterial rates of 97.4% against gram-positive S. aureus and 93.2% against gram-negative E. coli even after they were laundered for 30 times. Therefore, the titled zwitterionic sulfobetaine is safe to human for healthcare and wound dressing and shows a promising prospect on antibacterial textile application.

An effective approach to fabrication of antifouling ultrafiltration membrane based on zwitterionic polyimide

In this study, a new kind of membrane material, an aromatic zwitterionic polyimide (PI) copolymer, was synthesized through a one-pot polymerization reaction by precise variation of the molar ratios of different monomers with specific groups. The zwitterionic PI ultrafiltration (UF) membrane was prepared through an immersion precipitation phase inversion method and thoroughly characterized by scanning electron microscopy, water contact angle measurement, protein adsorption measurement, and UF experiment. The zwitterionic PI membrane showed significantly improved hydrophilicity and permeability and stable antifouling property. The amount of bovine serum albumin adsorbed on the zwitterionic PI membrane was considerably lower compared with the reference PI membrane. According to the cycle UF experiment for protein solution, the zwitterionic PI membrane had a water flux recovery ratio of 86.7%, compared with only 61.1% for the reference PI membrane. Moreover, the irreversible fouling of the zwitterionic PI membrane was significantly decreased, suggesting superior antifouling property. This new approach to the preparation of a zwitterionic polymer seems promising for potential applications in separation membrane.

Nanomaterials for membrane fouling control: accomplishments and challenges

We report a review of recent research efforts on incorporating nanomaterials-including metal/metal oxide nanoparticles, carbon-based nanomaterials, and polymeric nanomaterials-into/onto membranes to improve membrane antifouling properties in biomedical or potentially medical-related applications. In general, nanomaterials can be incorporated into/onto a membrane by blending them into membrane fabricating materials or by attaching them to membrane surfaces via physical or chemical approaches. Overall, the fascinating, multifaceted properties (eg, high hydrophilicity, superparamagnetic properties, antibacterial properties, amenable functionality, strong hydration capability) of nanomaterials provide numerous novel strategies and unprecedented opportunities to fully mitigate membrane fouling. However, there are still challenges in achieving a broader adoption of nanomaterials in the membrane processes used for biomedical applications. Most of these challenges arise from the concerns over their long-term antifouling performance, hemocompatibility, and toxicity toward humans. Therefore, rigorous investigation is still needed before the adoption of some of these nanomaterials in biomedical applications, especially for those nanomaterials proposed to be used in the human body or in contact with living tissue/body fluids for a long period of time. Nevertheless, it is reasonable to predict that the service lifetime of membrane-based biomedical devices and implants will be prolonged significantly with the adoption of appropriate fouling control strategies.

Advances in nonfouling materials: perspectives for the food industry

Fouling of complex food components onto food-processing materials affects food quality, food safety, and operating efficiency. Developments in nonfouling and fouling-release materials for biomedical and marine applications enable the potential for adaptation to food applications; however, challenges remain. The purpose of this review is to present different strategies to prevent fouling and/or facilitate foulant removal with a critical point of view for an application of such materials on food-processing surfaces. Nonfouling, self-cleaning, and amphiphilic materials are reviewed, including an explanation of the mechanism of action, as well as inherent limitations of each technology. Perspectives on future research directions for the design of food processing surfaces with antifouling and/or fouling release properties are provided.

Interface of covalently bonded phospholipids with a phosphorylcholine head: characterization, protein nonadsorption, and further functionalization

Surface anchored poly(methylhydrosiloxane) (PMHS) thin films on oxidized silicon wafers or glass substrates were functionalized via the SiH hydrosilylation reaction with the internal double bonds of 1,2-dilinoleoyl-sn-glycero-3-phosphorylcholine (18:2 Cis). The surface was characterized by X-ray photoelectron spectroscopy, contact angle measurements, atomic force microscopy, and scanning electron microscopy. These studies showed that the PMHS top layer could be efficiently modified resulting in an interfacial high density of phospholipids. Grafted phospholipids made the initially hydrophobic surface (θ = 106°) very hydrophilic and repellent toward avidin, bovine serum albumin, bovine fibrinogen, lysozyme, and α-chymotrypsin adsorption in phosphate saline buffer pH 7.4. The surface may constitute a new background-stable support with increased biocompatibility. Further possibilities of functionalization on the surface remain available owing to the formation of interfacial SiOH groups by Karstedt-catalyzed side reactions of SiH groups with water. The presence of interfacial SiOH groups was shown by zeta potential measurements. The reactivity and surface density of SiOH groups were checked by fluorescence after reaction of a monoethoxy silane coupling agent bearing Alexa as fluorescent probe.

Synthesis and functionalization of superparamagnetic poly-ε-caprolactone microparticles for the selective isolation of subpopulations of human adipose-derived stem cells

There has been a growing interest in using biofunctionalized magnetic particles for cell isolation. This paper describes the synthesis and characterization of magnetite-polymer (Fe(3)O(4)-poly-ε-caprolactone, magnetite-PCL) microparticles surface functionalized with amino and epoxy groups allowing easy covalent attachment of specific antibodies and subsequent ability to bind target cells. Particles with different sizes (4-135 µm), spherical shape and superparamagnetic behaviour (magnetite content of about 13 wt%) were obtained. The functionalized microparticles presented high protein-binding capacity (coupling efficiency of 47% for epoxy- and 71% for amino-functionalized particles) with a low level of non-specific binding. We have further investigated the influence of initial protein concentration, pH, ionic strength, temperature and incubation time on the capacity of amino-functionalized particles to bind protein molecules. The results showed that maximum protein coupling is rapidly achieved (≤5 h) at pH 5.5 and low ionic strength (0.05 M NaCl). Furthermore, when cultured in direct contact with osteoblast-like cells (Saos-2) or human-derived adipose stem cells (ASCs), the amino-functionalized particles did not affect the proliferation and morphology of the cells. As a proof of principle for the application of magnetic microparticles for cell isolation, CD105 (endoglin) antibody was coupled to the magnetic particle surface to bind subpopulations of human ASCs expressing the CD105 antigen. The isolation of CD105+ ASCs from a heterogeneous cell population was confirmed by flow cytometry analysis. Given the demonstrated potential of functionalized magnetite-PCL microparticles for selective cell isolation, we expect that these particles may be further applied in immuno-magnetic cell separation owing to their versatility and ease of surface modification.

Environmentally friendly antibacterial cotton textiles finished with siloxane sulfopropylbetaine

This paper reports a novel environmentally friendly antibacterial cotton textile finished with reactive siloxane sulfopropylbetaine(SSPB). The results show that SSPB can be covalently bound onto the cotton textile surface, imparting perdurable antibacterial activity. The textiles finished with SSPB have been investigated systematically from the mechanical properties, thermal stability, hydrophilic properties and antibacterial properties. It is found that the hydrophilicity and breaking strength are improved greatly after the cotton textiles are finished with SSPB. Additionally, the cotton textiles finished with SSPB exhibit good antibacterial activities against gram-positive bacteria Staphylococcus aureus (S.aureus, ATCC 6538), gram-negative bacteria Escherichia coli (E.coli, 8099) and fungi Candida albicans (C.albicans, ATCC 10231). Moreover, SSPB is nonleachable from the textiles, and it does not induce skin stimulation and is nontoxic to animals. Thus, SSPB is ideal candidate for environmentally friendly antibacterial textile applications.

Study of zwitterionic sulfopropylbetaine containing reactive siloxanes for application in antibacterial materials

Antibacterial agents receive a great deal of attention around the world due to the interesting academic problems of how to combat bacteria and of the beneficial health, social and economic effects of successful agents. Scientists are actively developing new antibacterial agents for biomaterial applications. This paper reports the novel antibacterial agent siloxane sulfopropylbetaine (SSPB), which contains reactive alkoxysilane groups. The structure and properties of SSPB were systematically investigated, with the results showing that SSPB contains both quaternary ammonium compounds and reactive siloxane groups. SSPB has good antibacterial activity against both Escherichia coli (E. coli, 8099) and Staphylococcus aureus (S. aureus, ATCC 6538). The minimal inhibition concentration is 70 μmol/ml SSPB against both E. coli and S. aureus. In addition, the SSPB antibacterial agent can be used in both weak acid and weak alkaline environments, functioning within the wide pH range of 4.0-9.0. The SSPB-modified glass surface killed 99.96% of both S. aureus and E. coli organisms within 24 h. No significant decrease was observed in this antibacterial activity after 20 washes. Moreover, SSPB does not induce a skin reaction and is nontoxic to animals. Thus, SSPB is an ideal candidate for future applications as a safe, environmentally friendly antibacterial agent.