Surface Modifying Additives Research Articles

Superhydrophilic and Underwater Superoleophobic Copper Mesh Coated with Bamboo Cellulose Hydrogel for Efficient Oil/Water Separation.

Super-wetting interface materials have shown great potential for applications in oil-water separation. Hydrogel-based materials, in particular, have been extensively studied for separating water from oily wastewater due to their unique hydrophilicity and excellent anti-oil effect. In this study, a superhydrophilic and underwater superoleophobic bamboo cellulose hydrogel-coated mesh was fabricated using a feasible and eco-friendly dip-coating method. The process involved dissolving bamboo cellulose in a green alkaline/urea aqueous solvent system, followed by regeneration in ethanol solvent, without the addition of surface modifiers. The resulting membrane exhibited excellent special wettability, with superhydrophilicity and underwater superoleophobicity, enabling oil-water separation through a gravity-driven "water-removing" mode. The super-wetting composite membrane demonstrated a high separation efficiency of higher than 98% and a permeate flux of up to 9168 L·m-2·h-1 for numerous oil/water mixtures. It also maintained a separation efficiency of >95% even after 10 cycles of separation, indicating its long-term stability. This study presents a green, simple, cost-effective, and environmentally friendly approach for fabricating superhydrophilic surfaces to achieve oil-water separation. It also highlights the potential of bamboo-based materials in the field of oil-water separation.

Amphiphilic silicones to mitigate lens epithelial cell growth on intraocular lenses

Silicone intraocular lenses (IOLs) that resist lens epithelial cell (LEC) growth would greatly improve patient outcomes. Herein, amphiphilic surface modifying additives (SMAs) were incorporated into an IOL-type diphenyl silicone to reduce LEC growth without compromising opto-mechanical properties. The SMAs were poly(ethylene oxide)-silane amphiphiles (PEO-SAs) [H-Si-ODMSm-block-PEO8-OCH3], comprised of a PEO segment and siloxane tether of varying lengths (m = 0, 13, and 30). These three SMAs were each blended into the addition cure diphenyl silicone at varying concentrations (5, 10, 15, 20, and 25 μmol g-1) wherein the wt% of PEO was maintained for all SMAs at a given molar concentration. The chemical crosslinking and subsequent retention of SMAs in modified silicones was confirmed. Key material properties were assessed following equilibration in both air and aqueous environments. Silicones modified with SMAs having longer tethers (m = 13 and 30) underwent rapid and substantial water-driven restructuring of PEO to the surface to form highly hydrophilic surfaces, especially as SMA concentration increased. The % transmittance was also maintained for silicones modified with these particular SMAs. The moduli of the modified silicones were largely unchanged by the SMA and remained in the typical range for silicone IOLs. When the three SMAs were introduced at the highest concentration, modified silicones remained non-cytotoxic and LEC count and associated alpha-smooth muscle actin (α-SMA) expression decreased with increasing tether length. These results demonstrate the potential of silicones modified with PEO-SA SMAs to produce LEC-resistant IOLs.

PLGA-CS-PEG Microparticles for Controlled Drug Delivery in the Treatment of Triple Negative Breast Cancer Cells

In this study, we explore the development of controlled PLGA-CS-PEG microspheres, which are used to encapsulate model anticancer drugs (prodigiosin (PGS) or paclitaxel (PTX)) for controlled breast cancer treatment. The PLGA microspheres are blended with hydrophilic polymers (chitosan and polyethylene glycol) in the presence of polyvinyl alcohol (PVA) that were synthesized via a water-oil-water (W/O/W) solvent evaporation technique. Chitosan (CS) and polyethylene glycol (PEG) were used as surface-modifying additives to improve the biocompatibility and reduce the adsorption of plasma proteins onto the microsphere surfaces. These PLGA-CS-PEG microspheres are loaded with varying concentrations (5 and 8 mg/mL) of PGS or PTX, respectively. Scanning electron microscopy (SEM) revealed the morphological properties while Fourier transform infrared spectroscopy (FTIR) was used to elucidate the functional groups of drug-loaded PLGA-CS-PEG microparticles. A thirty-day, in vitro, encapsulated drug (PGS or PTX) release was carried out at 37 °C, which corresponds to human body temperature, and at 41 °C and 44 °C, which correspond to hyperthermic temperatures. The thermodynamics and kinetics of in vitro drug release were also elucidated using a combination of mathematical models and the experimental results. The exponents of the Korsmeyer–Peppas model showed that the kinetics of drug release was well characterized by anomalous non-Fickian drug release. Endothermic and nonspontaneous processes are also associated with the thermodynamics of drug release. Finally, the controlled in vitro release of cancer drugs (PGS and PTX) is shown to decrease the viability of MDA-MB-231 cells. The implications of the results are discussed for the development of drug-encapsulated PLGA-CS-PEG microparticles for the controlled release of cancer drugs in treatment of triple negative breast cancer.

Amphiphilic zwitterionic-PDMS-based surface-modifying additives to tune fouling-release of siloxane-polyurethane marine coatings

Amphiphilic coatings have shown promising performance for marine applications to deter and limit biofouling. Hydrophobic marine coatings are unable to deter marine organisms that prefer hydrophobic surfaces for settlements, thus a series of amphiphilic additives were prepared and introduced to a hydrophobic system to attain surface amphiphilicity and improved performance without changing the base matrix. In this work, we report the successful synthesis of amphiphilic additives where highly incompatible blocks of hydrophobic polydimethylsiloxane (PDMS) and hydrophilic poly(sulfobetaine methacrylate) (poly(SBMA)) were connected, using ARGET ATRP (activators regenerated by electron transfer atom transfer radical polymerization) controlled radical polymerization technique. The surface characterization confirmed the presence of self-migrated amphiphilic additives to the surface of hydrophobic coating systems, and biological assessments indicated that the additives desirably improved fouling-release performance of the base hydrophobic system against macroalgal spores (Ulva linza) and barnacles (Amphibalanus amphitrite) while these additives had no detrimental effect on ability of the base matrix to release bacteria (Cellulophaga lytica), diatoms (Navicula incerta), and mussels (Geukensia demissa). Furthermore, this study not only reported the outstanding contribution of poly(SBMA)-PDMS additives towards contending with marine biofouling as well as the facile preparation of amphiphilic additives, but also concluded that several factors should be considered in the design of these additives for tailoring hydrophobic coatings: 1) PDMS block with a molecular weight of 1000 M¯n is preferred over higher molecular weights of PDMS; 2) hydrophilic portion between a range of 50% to 80% provides the desired amphiphilicity on a surface; and 3) poly(SBMA) block size does not necessarily impact the effectiveness of an additive.

Thromboresistance of Polyurethanes Modified with PEO-Silane Amphiphiles.

Surface-induced thrombosis is problematic in blood-contacting devices composed of silicones or polyurethanes (PUs). Poly(ethylene oxide)-silane amphiphiles (PEO-SA) are previously shown effective as surface modifying additives (SMAs) in silicones for enhanced thromboresistance. This study investigates PEO-SAs as SMAs in a PU at various concentrations: 5, 10, 25, 50, and 100µmolg-1 PU. PEO-SA modified PUs are evaluated for their mechanical properties, water-driven surface restructuring, and adhesion resistance against a human fibrinogen (HF) solution as well as whole human blood. Stability is assessed by monitoring hydrophilicity, water uptake, and mass loss following air- or aqueous-conditioning. PEO-SA modified PUs do not demonstrate plasticization, as evidenced by minimal changes in glass transition temperature, modulus, tensile strength, and percent strain at break. These also show a concentration-dependent increase in hydrophilicity that is sustained following air- and aqueous-conditioning for concentrations ≥25µmolg-1 . Additionally, water uptake and mass loss are minimal at all concentrations. Although protein resistance is not enhanced versus an HF solution, PEO-SA modified PUs have significantly reduced protein adsorption and platelet adhesion from human blood at concentrations ≥10µmolg-1 . Overall, this study demonstrates the versatility of PEO-SAs as SMAs in PU, which leads to enhanced and sustained hydrophilicity as well as thromboresistance.

Thromboresistance of Silicones Modified with PEO-Silane Amphiphiles.

The antifouling properties of poly(ethylene oxide) (PEO)-silane amphiphiles as surface-modifying additives (SMAs) in a condensation cure silicone have been previously demonstrated against simple protein solutions. Comprising an oligo(dimethylsiloxane) tether (m = 13 or 30) and PEO segment (n = 8), sustained protein resistance was achieved even in the absence of a cross-linkable triethoxysilane group, particularly when comprising the longer tether. To probe their potential for thromboresistance, PEO-silane amphiphile SMAs were used to bulk-modify silicones and evaluated for adhesion resistance against whole human blood under both static and dynamic conditions. Both a cross-linkable (XL diblock, m = 13) and a non-cross-linkable (Diblock, m = 30) SMA were evaluated at various concentrations (5-50 μmol SMA/g silicone) in a condensation cure silicone. Under static conditions, silicones modified with either SMA at concentrations of 10 μmol/g or greater were effective in reducing adhesion of human fibrinogen and platelets. Dynamic testing further showed that modified silicones were able to reduce protein adsorption and thrombus formation. This occurred at 5 and 10 μmol/g for silicones modified with XL diblock, m = 13 and Diblock, m = 30 SMAs, respectively. Combined, these results indicate the effectiveness of PEO-silane amphiphiles as SMAs in silicone for improved thromboresistance.

Stability of silicones modified with PEO-silane amphiphiles: Impact of structure and concentration

The efficacy of poly (ethylene oxide) (PEO)-based surface-modifying additives (SMAs), following the bulk-modification of silicones, requires sustained, water-driven PEO migration to the surface to achieve hydrophilicity and subsequent reduction of protein adsorption. Herein, a condensation cure silicone was modified with PEO-silane amphiphile SMAs (5–100 μmol per 1 g silicone) comprised of an oligo (dimethyl siloxane) (ODMS) tether, PEO segment and optional triethoxysilane (TEOS) crosslinkable group. This allowed us to confirm that the TEOS crosslinkable group was not necessary and that the ODMS tether (m = 13 or 30) could sufficiently physically anchor the amphiphile in the silicone network. Surface hydrophilicity was examined before and after aqueous conditioning, as well as mass loss and water uptake after conditioning. Overall, silicones modified with all amphiphilic SMAs produced increasingly hydrophilic surfaces and their hydrophilicity was maintained following conditioning. At all concentrations, all amphiphilic SMA modified silicones had minimal water uptake and mass loss, comparable to that of unmodified silicone. Finally, silicones modified with all amphiphilic SMAs ≥25 μmol exhibited exceptional protein resistance that was not appreciably diminished after conditioning.

Albumin conjugates and assemblies as versatile bio-functional additives and carriers for biomedical applications.

As the most abundant plasma protein, serum albumin has been extensively studied and employed for therapeutic applications. Despite its direct clinical use for the maintenance of blood homeostasis in various medical conditions, this review exclusively summarizes and discusses albumin-based bio-conjugates and assemblies as versatile bio-functional additives and carriers in biomedical applications. As one of the smallest-sized proteins in the human body, albumin is physiochemically stable and biochemically inert. Moreover, albumin is also endowed with abundant specific binding sites for numerous therapeutic compounds, which also endow it with superior bioactivities. Firstly, due to its small size and binding specificity, albumin alone or its derived assemblies can be utilized as competent drug carriers, which can deliver drugs through the enhanced permeability and retention (EPR) effect or actively target lesion sites through binding with gp60 and secreted protein acidic and rich in cysteine (SPARC) in tumor sites. Furthermore, its biochemical stability and inertness make it a safe and biocompatible coating material for use in biomedical applications. Albumin-based surface modifying additives can be used to functionalize both macro substrates (e.g. surfaces of medical devices or implants) and nanoparticle surfaces (e.g. drug carriers and imaging contrast agents). In this review, we elaborate on the synthesis and applications of albumin-based bio-functional coatings and drug carriers, respectively.

Protein Resistant Polymeric Biomaterials.

Toward improving implantable medical devices as well as diagnostic performance, the development of polymeric biomaterials having resistance to proteins remains a priority. Herein, we highlight key strategies reported in the recent literature that have relied upon improvement of surface hydrophilicity via direct surface modification methods or with bulk modification using surface modifying additives (SMAs). These approaches have utilized a variety of techniques to incorporate the surface hydrophilization agent, including physisorption, hydrogel network formation, surface grafting, layer-by-layer (LbL) assembly and blending base polymers with SMAs. While poly(ethylene glycol) (PEG) remains the gold standard, new alternatives have emerged such as polyglycidols, poly(2-oxazoline)s (POx), polyzwitterions, and amphiphilic block copolymers. While these new strategies provide encouraging results, the need for improved correlation between in vitro and in vivo protein resistance is critical. This may be achieved by employing complex protein solutions as well as strides to enhance the sensitivity of protein adsorption measurements.

Antifouling silicones based on surface-modifying additive amphiphiles.

Surface modifying additives (SMAs), which may be readily blended into silicones to improve anti-fouling behavior, must have excellent surface migration potential and must not leach into the aqueous environment. In this work, we evaluated the efficacy of a series of poly(ethylene oxide) (PEO)-based SMA amphiphiles which varied in terms of crosslinkability, siloxane tether length (m) and diblock versus triblock architectures. Specifically, crosslinkable, diblock PEO-silane amphiphiles with two oligodimethylsiloxane (ODMS) tether lengths [(EtO)3Si-(CH2)3-ODMS m -PEO8, m = 13 and 30] were compared to analogous non-crosslinkable, diblock (H-Si-ODMS m -PEO8) and triblock (PEO8-ODMS m -PEO8) SMAs. Prior to water conditioning, while all modified silicone coatings exhibited a high degree of water-driven surface restructuring, that prepared with the non-crosslinkable diblock SMA (m = 13) was the most hydrophilic. After conditioning, all modified silicone coatings were similarly hydrophilic and remained highly protein resistant, with the exception of PEO8-ODMS 30 -PEO8. Notably, despite twice the PEO content, triblock SMAs were not superior to diblock SMAs. For diblock SMAs, it was shown that water uptake and leaching were also similar whether or not the SMA was crosslinkable.

Effect of EDTA, Sodium Hypochlorite, and Chlorhexidine Gluconate with or without Surface Modifiers on Dentin Microhardness

IntroductionThis study aimed to evaluate the effects of root canal irrigants on the microhardness of root canal dentin in the presence and absence of surface-modifying agents. MethodsForty-eight root halves were prepared by longitudinal splitting of the distal roots of 24 freshly extracted mandibular human third molars and embedded in autopolymerizing acrylic resin, leaving the dentin surface exposed. After polishing, the microhardness values of the untreated dentin surfaces were recorded by using Vickers tester at the mid-root level. The root halves were randomly assigned to 6 groups composed of 8 samples each and treated for 5 minutes with one of the following irrigants: 17% EDTA, REDTA, 2% chlorhexidine gluconate (CHX), 2% CHX with surface modifiers (CHX-Plus), 6% NaOCl, or 6% NaOCl with surface modifiers (Chlor-XTRA). After surface treatment, dentin microhardness values were recorded at close proximity to the initial indentation areas. Experimental data were statistically analyzed by using the t test and one-way analysis of variance, followed by Tukey honestly significant difference test at α = 0.05. ResultsEDTA, REDTA, NaOCl, and Chlor-XTRA significantly decreased the microhardness of root dentin compared with intact controls (P < .05). ConclusionsThe addition of surface modifiers to the irrigants did not affect the microhardness of the samples.

Efficient visible light photo-Fenton-like degradation of organic pollutants using in situ surface-modified BiFeO3 as a catalyst

The visible light photo-Fenton-like catalytic performance of BiFeO3 nanoparticles was investigated using Methyl Violet (MV), Rhodamine B (RhB) and phenol as probes. Under optimum conditions, the pseudo first-order rate constant (k) was determined to be 2.21 × 10−2, 5.56 × 10−2 and 2.01 × 10−2 min−1 for the degradation of MV (30 μmol/L), RhB (10 μmol/L) and phenol (3 mmol/L), respectively, in the BiFeO3-H2O2-visible light (Vis) system. The introduction of visible light irradiation increased the k values of MV, RhB and phenol degradation 3.47, 1.95 and 2.07 times in comparison with those in dark. Generally, the k values in the BiFeO3-H2O2-Vis system were accelerated by increasing BiFeO3 load and H2O2 concentration, but decreased with increasing initial pollutant concentration. To further enhance the degradation of pollutants at high concentrations, BiFeO3 was modified with the addition of surface modifiers. The addition of ethylenediamineteraacetic acid (EDTA, 0.4 mmol/L) increased the k value of MV degradation (60 μmol/L) from 1.01 × 10−2 min−1 in the BiFeO3-H2O2-Vis system to 1.30 min-1 in the EDTA-BiFeO3-H2O2-Vis system by a factor of 128. This suggests that in situ surface modification can enable BiFeO3 nano-particles to be a promising visible light photo-Fenton-like catalyst for the degradation of organic pollutants.

Hydrothermal Synthesis of Surface-Modified, Manganese-Doped TiO2 Nanoparticles for Photodegradation of Methylene Blue

Abstract There has been a growing trend toward the addition of surface modifiers, surfactants, or capping agents to the precursors of titanium dioxide nanoparticles to tailor their morphology, structure, and size. In this study, surface-modified, manganese-doped titanium dioxide nanoparticles were successfully synthesized under mild hydrothermal conditions (pressure is autogenous; temperature, 250°C; time, 18 h). Using different molar ratios, we applied caprylic acid to change the surface chemistry and photocatalytic efficiency of manganese-doped titanium dioxide nanoparticles. Reagent grade titanium dioxide and manganese dioxide were the precursors, and concentrated hydrogen chloride was used as a solvent. Synthesized nanoparticles were characterized using powder x-ray diffraction, transmission electron microscopy, BET surface area, and ultraviolet-visible spectroscopy. Photodegradation studies of methylene blue were then carried out using ultraviolet and sunlight irradiation to compare the photocatalyti...

Synthesis of surface-modified monoclinic ZrO2 nanoparticles using supercritical water

We succeeded in simple and rapid synthesis of surface-modified monoclinic ZrO2 nanoparticles using a supercritical hydrothermal method. The precursor Zr(OH)4 was treated in the presence of various surface modifiers with carboxyl group (–COOH) in a batch-type reactor at 400 °C for 10 min. Oleic, sebacic, dodecanedioic, and 12-aminododecanoic acids were used as surface modifiers. Addition of surface modifiers resulted in smaller particle (crystallite) sizes than the unmodified nanoparticles, suggesting that there is an interaction between the surface modifiers and the nanoparticles. The reduced particle size in the presence of surface modifiers was attributed to the inhibition of the growth of the crystalline surface due to the surface modification. The FT-IR spectra revealed that the surface modifiers were attached to the surface of the nanoparticles through coordination bonds between the carboxylate group (–COO−) and the Zr ion. The FT-IR spectra also confirmed the presence of functional groups, such as methyl (–CH3), carboxyl (–COOH), and amine (–NH2), at the surface. The surface modification was also verified by the thermogravimetric analysis. The number of the surface modifiers attached to the surface of the products was about 2 molecules per nm2. The nanoparticles with carboxyl and amine surface functional groups were water dispersible; the isoelectric point shifted to low pH ranges because of the nature of the groups.

Understanding and Controlling Reactivity of Unsaturated Oxygenates and Polyols on Metal Catalysts

The production of fuels and chemicals from biomass requires heterogeneous catalysts that facilitate selective reactions of highly functional oxygenates. Although designing catalysts for high selectivity is a universal challenge in heterogeneous catalysis research, the problem is particularly acute for highly functional molecules, which contain two or more functional groups that may react over metal surfaces. This perspective article focuses on recent efforts to develop structure–property relations on metal surfaces and catalysts for two classes of highly functional molecules: multifunctional oxygenates such as α,β-unsaturated aldehydes and furanic compounds, and polyfunctional oxygenates such as glycerol and other polyols. Recent results from comparative reaction studies over a variety of catalysts, surface science experiments, and computational investigations suggest an array of approaches for producing more selective catalysts, many relying on the addition of multiple metals or other surface modifiers. General strategies that appear to show promise in the selective reactions of unsaturated oxygenates and of polyols are discussed in detail.

Synthesis and Development of a Multifunctional Self-Decontaminating Polyurethane Coating

A unique, durable, nonleaching antimicrobial urethane coating possessing energy-dampening properties is reported. Five novel diol-functionalized quaternary ammonium bromide salts were designed, synthesized, and cross-linked with a commercial polyisocyanate to afford novel multifunctional self-decontaminating coatings. Leaching of the antimicrobial into the environment is eliminated because of the biocidal tether. The effectiveness of these molecules to self-concentrate at the air-polymer interface without addition of other surface modifying additives proved extremely advantageous, and consequently resulted in microphase separation as confirmed by AFM. The coatings were designed to continuously decontaminate against a variety of pathogenic bacteria in addition to affording preliminary dampening properties. Minimum inhibitory concentration studies as well as surface antimicrobial evaluations were conducted using both Gram-positive and Gram-negative bacteria. Additionally, viscoelastic properties, hardness, tack, and surface energy measurements were used to correlate with coating performance.

Surface immobilization of elastin‐like polypeptides using fluorinated surface modifying additives

Elastin-like polypeptide (ELP) surface modification represents a valuable approach for the development of biomaterials in a wide range of medical applications. In this study, ELP surface modification has been achieved through the use of elastin cross-linking peptide (ECP) bioactive fluorinated surface modifiers (ECP-BFSMs). The synthesis of low molecular weight fluorinated additives was described and their subsequent blending with a base polycarbonate urethane (PCNU) was shown to successfully enrich the surface to allow for ELP surface cross-linking via lysine moieties on the peptide segments of the ECP-BFSMs. The kinetics for the surface migration of fluorescent ECP-BFSMs was studied over a 2-week period by two-photon confocal microscopy. A decrease in advancing contact angle from 87.9° to 75.3° was observed for ECP-BFSM modified PCNU and was associated with the presence of ECP peptides on the surface. X-ray photoelectron spectroscopy demonstrated an increase in surface atomic percent of fluorine (from 0.2 to 7.2%) and nitrogen (from 1.0 to 3.0%) associated with the surface localization of fluoro groups and amide groups associated with the peptides in the ECP-BFSMs. A further increase in surface atomic percent of nitrogen (from 3.0 to 8.3%) was observed after ELP surface cross-linking. These ELP-modified surfaces were shown to promote increased smooth muscle cell adhesion, spreading and retention over a 7-day culture period relative to their non-ELP4 analogs. This novel surface modifying additive approach may be used for various biomimetic applications since it generates a stable ECM-like surface retained onto a relatively inert fluorinated background.

Polyol mediated nano size zinc oxide and nanocomposites with poly(methyl methacrylate)

Organophilic nano ZnO particles have been synthesized in various diols (ethylene glycol - EG, 1,2 propane diol - PD, 1,4 butane diol - BD and tetra(ethylene glycol) - TEG) in the presence of p-toluenesulfonic acid, p-TsOH, as an end capping agent. The addition of p-TsOH reduces the ZnO particle size and increases its crystallite size. With increasing diol main chain length the ZnO particle size increases (EG (32 nm) < PD (33 nm) < BD (72 nm) < TEG (86 nm)). Using the as- synthesized and unmodified ZnO nanocomposites with poly(methyl methacrylate), PMMA, matrix have been prepared by the in-situ bulk polymerization of methyl methacrylate, MMA. The addition of surface modifiers is avoided which is an advantage for the application since they can influence other properties of the material. ZnO particles, especially those with smaller particle sizes (EG - 32 nm, PD - 33 nm) showed enhanced effect on the thermal stability of PMMA, ultraviolet, UV, absorption and transparency for visible light. Transparent materials with high UV absorption and with enhanced resist- ance to sunlight were obtained by optimizing the nanocomposite preparation procedure using ZnO particles of about 30 nm size in concentrations between 0.05 and 0.1 wt%. The reported nanocomposite preparation procedure is compatible with the industrial process of PMMA sheet production.

Bioactivation of porous polyurethane scaffolds using fluorinated RGD surface modifiers

Biomaterial scaffolds for tissue engineering require appropriate cell adhesion, proliferation, and infiltration into their three-dimensional (3D) porous structures. Surface modification techniques have the potential to enhance cell infiltration into synthetic scaffolds while retaining bulk material properties intact. The objective of this work was to assess the potential of achieving a uniform surface modification in 3D porous constructs through the blending of surface-modifying additives known as bioactive fluorinated surface modifiers (BFSMs) with a base polyurethane material. By coupling RGD peptides to the fluorinated surface modifiers to form RGD-BFSMs, the BFSMs can act as a vehicle for the delivery of RGD moieties to the surface without direct covalent attachment to the polymer substrate. Fluorescent RGD-BFSMs were shown to migrate to the polymer-air interfaces within the porous scaffolds by two-photon confocal microscopy. A-10 rat aortic smooth muscle cells were cultured for 4 weeks on nonmodified and RGD-BFSM-modified porous scaffolds, and cell adhesion, proliferation, and viability were quantified at different depths. RGD-BFSM-modified scaffolds showed significantly greater cell numbers within deeper regions of the scaffolds, and this difference became more pronounced over time. This study demonstrates an effective approach to promote cell adhesion and infiltration within thick (approximately 0.5 cm) porous synthetic scaffolds by providing a uniform distribution of adhesive peptide throughout the scaffolds without the use of covalent surface reaction chemistry.

Caseinate based biodegradable films with improved water resistance

AbstractProteins are considered as an interesting alternative to traditional synthetic polymers in packaging applications. Sodium caseinate based films can be used in such area, but some of their properties need to be improved. The objective of this work was to improve water resistance of caseinate based films plasticized with triethanolamine (TEA). First, plasticized films were crosslinked by formaldehyde (HCHO) or by electron beam irradiation. The crosslinking efficiency was correlated to the decrease of protein solubility in water determined from a 280 nm absorbance method. The comparison between the two crosslinking methods showed that formaldehyde crosslinking was significantly more efficient than irradiation. The HCHO crosslinking technique was selected for the following of the study. Nevertheless, even for highly crosslinked samples, the plasticizer exuded out of the film. A second part of this work was focused on the effect of surface modification on plasticizer exudation in TEA plasticized caseinate films. Considering that silicone grease coating onto the film surface was able to control TEA exudation, surface modifying additives (SMA) based on NaCAS and organo‐silicones were used to modify films surface properties. Surface wettability and energy were determined from contact angle measurements. TEA exudation ratios in water were also monitored for films containing SMA. SMA were less efficient in controlling TEA exudation rates but could significantly reduce surface energy to 42 mJ m2. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010