Polyethylene Glycol Grafting Research Articles

Effect of polyvinyl caprolactam–polyvinyl acetate–polyethylene glycol graft copolymer on bioadhesion and release rate property of eplerenone pellets

The present study involved the design and development of oral bioadhesive pellets of eplerenone. A solid dispersion of eplerenone was developed with a hydrophilic carrier, polyvinyl caprolactam–polyvinyl acetate–polyethylene glycol graft copolymer (Soluplus®). Bioadhesive pellets were prepared from this solid dispersion using a combination of HPMC K4M and Carbopol 934P. Both the solid dispersion and the pellets were evaluated for various physicochemical properties such as solubility, entrapment efficiency, drug content, surface morphology, mucoadhesion and swelling behavior. Analysis carried out using FT-IR, DSC and XRD found no interaction between the eplerenone and excipients. The solid dispersion had irregular-shaped smooth-surfaced particles of diameter 265 ± 105.5 μm. In TEM analysis, eplerenone particles of size 79–120 nm were found. The solubility and dissolution of eplerenone in the Soluplus®-based solid dispersion were 5.26 and 2.50 times greater, respectively. Investigation of the swelling behavior of the pellets showed that the thickness of the gel layer increased continuously over the duration of the study. Moreover, a correlation was observed between the thickness and strength of the gel layer and the percentage release. The mechanism of drug release was found to be non-Fickian (anomalous), with the release kinetics approaching first-order kinetics. The bioavailability of the eplerenone bioadhesive pellet formulation was studied using Wistar rats and was found to be improved. An in vivo mucoadhesion study showed that the pellets are retained for 24 h in rabbits. It was concluded that Soluplus® had a positive effect on the solubility and dissolution of pellets without affecting the bioadhesion.

Solubility and dissolution performances of spray-dried solid dispersion of Efavirenz in Soluplus

Efavirenz (EFV), a first-line anti-HIV drug largely used as part of antiretroviral therapies, is practically insoluble in water and belongs to BCS class II (low solubility/high permeability). The aim of this study was to improve the solubility and dissolution performances of EFV by formulating an amorphous solid dispersion of the drug in polyvinyl caprolactam–polyvinyl acetate–polyethylene glycol graft copolymer (Soluplus®) using spray-drying technique. To this purpose, spray-dried dispersions of EFV in Soluplus® at different mass ratios (1:1.25, 1:7, 1:10) were prepared and characterized using particle size measurements, SEM, XRD, DSC, FTIR and Raman microscopy mapping. Solubility and dissolution were determined in different media. Stability was studied at accelerated conditions (40 °C/75% RH) and ambient conditions for 12 months. DSC and XRD analyses confirmed the EFV amorphous state. FTIR spectroscopy analyses revealed possible drug–polymer molecular interaction. Solubility and dissolution rate of EFV was enhanced remarkably in the developed spray-dried solid dispersions, as a function of the polymer concentration. Spray-drying was concluded to be a proper technique to formulate a physically stable dispersion of amorphous EFV in Soluplus®, when protected from moisture.

Surface modification of polyurethane via creating a biocompatible superhydrophilic nanostructured layer: role of surface chemistry and structure

ABSTRACTAdvanced surface modification approaches of biomaterials alongside the advent of sophisticated analytical techniques have provided a great opportunity to understand how the physicochemical characteristics of materials determine cell–surface dynamics at molecular and atomic scale. However, there are still many contradictory reports, which are mainly due to inadequate information about the role of the two parameters of surface chemistry and structure and their synergistic effect as an adequate predictor of biological performance. Here, surface parameters were altered by grafting of poly ethylene glycol (PEG) on polyurethane (PU) surfaces through a superhydrophilic modification method. In this study, surface modification of PU films by PEG thin layer via grafting technique and TiO2 nanoparticle entrapment in the brush polymers was investigated. The surface modification led to a reduction in protein adsorption and bacterial attachment by 8.7 times and 71% respectively with no cytotoxicity effect on HeLa cells. It was also observed that when PU surface became superhydrophilic the bacterial adhesion becomes independent of bacterium type. In general, it was observed that the impact of topographical changes on the biocompatibility and biofilm formation becomes significantly more profound than that of the surface chemistry alteration.

Effect of PEG Grafting Density and Hydrodynamic Volume on Gold Nanoparticle-Cell Interactions: An Investigation on Cell Cycle, Apoptosis, and DNA Damage.

In this study, interactions of polyethylene glycol (PEG)-coated gold nanoparticles (AuNPs) with cells were investigated with particular focus on the relationship between the PEG layer properties (conformation, grafting density, and hydrodynamic volume) and cell cycle arrest, apoptosis, and DNA damage. Steric hindrance and PEG hydrodynamic volume controlled the protein adsorption, whereas the AuNP core size and PEG hydrodynamic volume were primary factors for cell uptake and viability. At all PEG grafting densities, the particles caused significant cell cycle arrest and DNA damage against CaCo2 and PC3 cells without apoptosis. However, at a particular PEG grafting density (∼0.65 chains/nm(2)), none of these severe damages were observed on 3T3 cells indicating discriminating behavior of the healthy (3T3) and cancer (PC3 and CaCo2) cells. It was concluded that the PEG grafting density and hydrodynamic volume, tuned with the PEG concentration and AuNP size, played an important role in particle-cell interactions.

Hemocompatibility and oxygenation performance of polysulfone membranes grafted with polyethylene glycol and heparin by plasma-induced surface modification.

Polyethylene glycol (PEG) and heparin (Hep) were grafted onto polysulfone (PSF) membrane by plasma-induced surface modification to prepare PSF-PEG-Hep membranes used for artificial lung. The effects of plasma treatment parameters, including power, gas type, gas flow rate, and treatment time, were investigated, and different PEG chains were bonded covalently onto the surface in the postplasma grafting process. Membrane surfaces were characterized by water contact angle, PEG grafting degree, attenuated total reflectance-Fourier transform infrared spectroscopy, ultraviolet-visible spectrophotometry, X-ray photoelectron spectroscopy, critical water permeability pressure, and scanning electron microscopy. Protein adsorption, platelet adhesion, and coagulation tests showed significant improvement in the hemocompatibility of PSF-PEG-Hep membranes compared to pristine PSF membrane. Gas exchange tests through PSF-PEG6000-Hep membrane showed that when the flow rate of porcine blood reached 5.0L/min, the permeation fluxes of O2 and CO2 reached 192.6 and 166.9mL/min, respectively, which were close to the gas exchange capacity of a commercial membrane oxygenator. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1737-1746, 2017.

Adsorption of Plasma Proteins onto PEGylated Lipid Bilayers: The Effect of PEG Size and Grafting Density.

Lipid bilayers grafted with polyethylene glycol (PEG) of different sizes (Mw = 750, 2000, and 5000) and grafting densities (1.6-25 mol % of PEGylated lipid in dipalmitoylphosphatidylcholine (DPPC) lipid molecules) were simulated with human serum albumin (HSA) using coarse-grained force fields. At low enough grafting density, the PEG has a conformation similar to that of an isolated chain in water, and its Flory radius RF is smaller than the distance between the grafting points (d), which is the so-called "mushroom" regime. In contrast, densely grafted PEG chains (RF > d) extend like brushes, with brush layer thickness given by the Alexander-de Gennes theory. A nearly spherical HSA added to this simulation migrates to the bilayer surface because of the charge interactions between anion residues of HSA and cationic cholines of DPPC, but this HSA-bilayer binding can be sterically suppressed by the PEG chains to an extent that depends on the PEG size and grafting density. In particular, regardless of the extent of the coverage of the PEG on the bilayer, the binding between HSAs and bilayers is suppressed by the PEG layer in a brush but not in a mushroom, indicating that the attractive force between proteins and bilayers can overcome the steric effect of the PEG layer in the mushroom state or in the transition region from mushroom to brush. This helps explain and clarify experiments that show much less adsorption of plasma proteins onto the particle or membrane surface when PEGs are in the brush rather than in the mushroom state.

Efficiency of SPIONs functionalized with polyethylene glycol bis(amine) for heavy metal removal

Hybrid magnetic nanoparticles based on poly(methylmethacrylate) (PMMA) and super-paramagnetic iron oxide nanopaticles (SPIONs) with selective surface modification has been developed for heavy metal removal by applying external magnetic fields. The nanoparticles were prepared by the emulsion polymerization technique in an aqueous suspension of SPIONs. The hydrolysis of carboxyl functional group was then applied for grafting polyethylene glycol bis(amine)(PEG-bis(amine)) onto the PMMA-coated SPIONs. The morphology, the chemical structure and the magnetic properties of the grafted nanoparticles were investigated. The efficiency of the hybrid nanoparticles for heavy metal removal were conducted on Pb(II), Hg(II), Cu(II) and Co(II) in aqueous solutions.The metal concentration in the solutions after separation by the hybrid nanoparticles was determined by inductively coupled plasma optical emission spectrometer (ICP-OES). The results show the heavy metal uptake ratios of 0.08, 0.04, 0.03, and 0.01mM per gramme of the grafted SPIONs for Pb(II), Hg(II), Cu(II), and Co(II), respectively. A competitive removal of Cu(II), Pb(II), Co(II) and Hg(II) ions in mixed metal salt solutions has also been studied.The heavy metal removal efficiency of the hybrid nanoparitcles was found to depend on the cation radius, in accordance with capture of metal ions by the amine group.

Grafting polyethylene glycol dicrylate (PEGDA) to cell walls of poplar wood in two steps for improving dimensional stability and durability of the wood polymer composite

Abstract Polyethylene glycol (PEG) treatment is an effective approach to endow wood with higher dimensional stability (DS), which is still a concern under humid conditions. In this study, poplar wood was first treated with methacryloyl chloride to introduce methacryl groups in the cell wall. Then functional PEG served as modifier, and copolymerization was conducted in the second step to prepare PEG-diacrylate (PEGDA) modified samples. The resultant wood polymer composites (WPCs) were characterized by solid state NMR, field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). The physical and mechanical properties of the WPCs were also evaluated, such as anti-swelling efficiency (ASE), water uptake, dynamic hydrophilicity (contact angles), and thermal stability. The results show that the copolymerized WPC achieved 51.4% ASE with leaching <3.0%. Moreover, the surface hardness and water resistance of the wood are also greatly improved.

Critical Length of PEG Grafts on lPEI/DNA Nanoparticles for Efficient in Vivo Delivery.

Nanoparticle-mediated gene delivery is a promising alternative to viral methods; however, its use in vivo, particularly following systemic injection, has suffered from poor delivery efficiency. Although PEGylation of nanoparticles has been successfully demonstrated as a strategy to enhance colloidal stability, its success in improving delivery efficiency has been limited, largely due to reduced cell binding and uptake, leading to poor transfection efficiency. Here we identified an optimized PEGylation scheme for DNA micellar nanoparticles that delivers balanced colloidal stability and transfection activity. Using linear polyethylenimine (lPEI)-g-PEG as a carrier, we characterized the effect of graft length and density of polyethylene glycol (PEG) on nanoparticle assembly, micelle stability, and gene delivery efficiency. Through variation of PEG grafting degree, lPEI with short PEG grafts (molecular weight, MW 500–700 Da) generated micellar nanoparticles with various shapes including spherical, rodlike, and wormlike nanoparticles. DNA micellar nanoparticles prepared with short PEG grafts showed comparable colloidal stability in salt and serum-containing media to those prepared with longer PEG grafts (MW 2 kDa). Corresponding to this trend, nanoparticles prepared with short PEG grafts displayed significantly higher in vitro transfection efficiency compared to those with longer PEG grafts. More importantly, short PEG grafts permitted marked increase in transfection efficiency following ligand conjugation to the PEG terminal in metastatic prostate cancer-bearing mice. This study identifies that lPEI-g-PEG with short PEG grafts (MW 500–700 Da) is the most effective to ensure shape control and deliver high colloidal stability, transfection activity, and ligand effect for DNA nanoparticles in vitro and in vivo following intravenous administration.

Novel Long-Circulating Liposomes Consisting of PEG Modified β-Sitosterol for Gambogic Acid Delivery.

Long-circulating liposome is an effective formulation in field of cancer treatment. However, high expenditure of formulation and high dose of cholesterol severely restrict its application. In this paper, we developed a method by grafting polyethylene glycol 2000 on β-sitosterol succinic anhydride ester to obtain relatively cheap polyethylene glycol-β-sitosterol conjugates, which were used to prepare long-circulating liposome without cholesterol. Gambogic acid which is an effective antitumor ingredient with very short half-life, was used as a model drug to prepare long-circulating liposome in this research. Meanwhile, the characteristics, pharmacokinetics and distribution of this novel long-circulating liposome were also investigated in comparison with other gambogic acid formulations. Polyethylene glycol-β-sitosterol conjugates were synthesized, different liposomal formulations were also prepared by ethanol injection method, and the obtained nanoparticles were characterized by dynamic light scattering and transmission electron microscope. The long-circulating effect, pharmacokinetics and distribution of gambogic acid in rats were also explored. 1HNMR confirmed that polyethylene glycol-β-sitosterol conjugates were synthesized successfully. Novel long-circulating liposome was successfully prepared by ethanol injection method attaining a entrapment efficiency of 89.4%, exhibiting a homogeneous particle size of 245.2 nm and -24.3 mV zeta potential with smooth continuous surface. This novel long-circulating liposome demonstrated better long-circulating effect than ordinary long-circulating liposome. The novel long-circulating liposome as-prepared not only could reduce cost of grafting polyethylene glycol on macromolecular phospholipid, but also no cholestrol in preparation was applied, expanding the application of liposome as a formulation in the field of lowering blood lipid. Therefore, polyethylene glycol-β-sitosterol conjugates are recommended substitute for polyethylene glycol modified phospholipid to prepare long-circulating liposomes.

A new approach in compatibilization of the poly(lactic acid)/thermoplastic starch (PLA/TPS) blends

In this study, a new compatibilizer was synthesized to improve the compatibility of the poly(lactic acid)/thermoplastic starch blends. The compatibilizer was based on maleic anhydride grafted polyethylene glycol grafted starch (mPEG-g-St), and was characterized using Fourier transform infrared spectroscopy (FTIR), dynamic mechanical thermal analysis (DMTA) and back titration techniques. The results indicated successful accomplishment of the designed reactions and formation of a starch cored structure with many connections to m-PEG chains. To assess the performance of synthesized compatibilizer, several PLA/TPS blends were prepared using an internal mixer. Consequently, their morphology, dynamic-mechanical behavior, crystallization and mechanical properties were studied. The compatibilizer enhanced interfacial adhesion, possibly due to interaction between free end carboxylic acid groups of compatibilizer and active groups of TPS and PLA phases. In addition, biodegradability of the samples was evaluated by various methods consisting of weight loss, FTIR-ATR analysis and morphology. The results revealed no considerable effect of compatibilizer on biodegradability of samples.

Tailoring the surface properties of polypropylene films through cold atmospheric pressure plasma (CAPP) assisted polymerization and immobilization of biomolecules for enhancement of anti-coagulation activity

Enhancement of anti-thrombogenic properties of polypropylene (PP) to avert the adsorption of plasma proteins (fibrinogen and albumin), adhesion and activation of the platelets are very important for vast biomedical applications. The cold atmospheric pressure plasma (CAPP) assisted polymerization has potential to create the specific functional groups such as OCO, CO, CN and SS. on the surface of polymeric films using selective precursor in vapour phase to enhance anti-thrombogenic properties. Such functionalized polymeric surfaces would be suitable for various biomedical applications especially to improve the blood compatibility. The eventual aspiration of the present investigation is to develop the biofunctional coating onto the surface of PP films using acrylic acid (AAc) and polyethylene glycol (PEG) as a precursor in a vapour phase by incorporating specific functional groups for immobilization of biomolecules such as heparin (HEP), chitosan (CHI) and insulin (INS) on the surface of plasma modified PP films. The surface properties such as hydrophilicity, chemical composition, surface topography of the surface modified PP films were analyzed by contact angle (CA), Fourier transform infrared spectroscopy (FTIR), X-ray photo electron spectroscopy (XPS) and atomic force microscopy (AFM). Furthermore the anti-thrombogenic properties of the surface modified PP films were studied by in vitro tests which include platelet adhesion and protein adsorption analysis. It was found that the anti-thrombogenic properties of the PP films are effectively controlled by the CAPP grafting of AAc and PEG followed by immobilization of biomolecules of heparin, chitosan and insulin. The grafting and immobilization was confirmed by FTIR and XPS through the recognition of specific functional groups such as COOH, CO, SS and CN. on the surface of PP film. Furthermore, the surface morphology and hydrophilic nature of the PP films also tailored significantly by the successful grafting and immobilization which is confirmed by AFM and CA analysis. Owing to the physico-chemical changes on the surface of PP films induced by CAPP assisted polymerization, the anti-thrombogenic properties of PP films were enhanced as confirmed by in vitro analysis.

Synthesis and Characterization of Xylan Grafted with Polyethylene Glycol in Ionic Liquid and Their Use as Moisture‐Absorption/Retention Biomaterials

The objective of this study is to broaden the application of xylan as moisture‐absorption/retention biomaterials by grafting polyethylene glycol (PEG) on xylan backbone. Ionic liquid 1‐allyl‐3‐methylimidazolium chloride ([Amim]Cl) and 4,4‐diphenylmethane diisocyanate are used as reaction media and coupling reagent, respectively. FT‐IR, 1H‐NMR, and gel permeation chromatography analyses indicate the successful occurrence of the grafting reaction. Thermogravimetric analysis/derivative thermogravimetry indicates that the thermal stability of xylan increases after the grafting of the PEG side chains. With an increase of the degree of substitution of xylan‐g‐PEG, the molecular weight (Mw) of PEG side chains (1000 and 5000 g mol−1), and the relative humidity of environment, the moisture‐absorption/retention ratio of xylan‐g‐PEG increases. To evaluate the biodegradability/biocompatibility of this promising material, the ratio of biochemical oxygen demand to chemical oxygen demand of xylan‐g‐PEG and the cytotoxicity are tested on the samples. The results indicate that PEG‐modified xylan has great potential as moisture‐absorption/retention biomaterials. image

Hydrophilicity improvement of mercerized bacterial cellulose films by polyethylene glycol graft

In this work, polyethylene glycol (PEG), of tree distinct molar masses (200, 300 and 400gmol⿿1), was grafted onto mercerized bacterial nanocellulose (BNCm) and applied to produce nanofilms (BNCm-PEG). The products BNCm-PEG were characterized by NMR and thermal analysis. Solid-state NMR and X-ray diffraction analyses exhibited no significant differences in index of BNCm-PEG derivatives compared to BNCm, indicating that grafting reaction did not modify the BNCm crystalline structure. The apparent contact angle of the films showed that BNCm-PEG films exhibited a pronounced increase in the polar components (BNCm: 8.1mNm⿿1 vs BNCm-PEG400: 29.4mNm⿿1), and a decrease in dispersive components (BNCm: 41.7mNm⿿1 vs BNCm-PEG400: 35.2mNm⿿1) of the surface free energy. The BNCm-PEG films were more hydrophilic than BNCm and retained the biocompatibility with L929 fibroblast cells culture.

Effect of cationic grafted copolymer structure on the encapsulation of bovine serum albumin

The aim of the present study was to evaluate a library of poly-l-lysine (PLL)-graft (g)-polyethylene glycol (PEG) copolymers for the ability to encapsulate effectively a model protein, bovine serum albumin (BSA), and to characterize the stability and protein function of the resulting nanoparticle. A library of nine grafted copolymers was produced by varying PLL molecular weight and PEG grafting ratio. Electrostatic self-assembly of the protein and the grafted copolymer drove encapsulation.The formation of protein/polymer nanoparticles with a core/shell structure was confirmed using PAGE, dynamic light scattering, and electron microscopy. Encapsulation of the BSA into nanoparticles was strongly dependent on the copolymer-to-protein mass ratio, PEG grafting ratio, and PLL molecular weight. A copolymer-to-protein mass ratio of 7:1 and higher was generally required for high levels of encapsulation, and under these conditions, no loss of protein activity was observed. Copolymer characteristics also influenced nanoparticle resistance to polyanions and protease degradation. The results indicate that a copolymer of 15–30kDa PLL, with a PEG grafting ratio of 10:1, is most promising for protein delivery.

Encapsulation of clozapine in polymeric nanocapsules and its biological effects

Clozapine is an effective atypical antipsychotic drug that unfortunately exhibits poor oral bioavailability. Moreover, the clinical use of the compound is limited because of its numerous unfavorable and unsafe side effects. Therefore, the aim of the present study was the development of a new nanocarrier for a more effective clozapine delivery. Here, clozapine was encapsulated into polymeric nanocapsules (NCs). Polyelectrolyte multilayer shells were constructed by the technique of sequential adsorption of polyelectrolytes (LbL) using biocompatible polyanion PGA (Poly-l-glutamic acid, sodium salt) and polycation PLL (poly-l-lysine) on clozapine-loaded nanoemulsion cores. Pegylated external layers were prepared using PGA-g-PEG (PGA grafted by PEG (polyethylene glycol)). Clozapine was successfully loaded into the PLL-PGA nanocarriers (CLO-NCs) with an average size of 100nm. In vitro analysis of the interactions of the CLO-NCs with the cells of the mononuclear phagocytic system (MPS) was conducted. Cell biocompatibility, phagocytosis potential, and cellular uptake were studied. Additionally, the biodistribution and behavioral effects of the encapsulated clozapine were also studied. The results indicate that surface modified (by PEG grafting) polymeric PLL-PGA CLO-NCs are very promising nanovehicles for improving clozapine delivery.

A universal aqueous-based antifouling coating for multi-material devices

Event Abstract Back to Event A universal aqueous-based antifouling coating for multi-material devices Sharon Goh1*, Yafei Luan2, Xiaojing Wang2*, Hong Chen2*, John L. Brash1 and Qiyin Fang1* 1 McMaster University, School of Biomedical Engineering, Canada 2 Soochow University, Polymer Science and Engineering, China Introduction: Preventing unwanted protein adsorption is important to improve implant biocompatibility, reduce biofouling, and control cell adhesion. A typical approach involves grafting polymers to alter surface chemistry. However, many surface modification protocols require harsh chemical conditions and solvents which may not be suitable for some materials. Thus, antifouling protocols need to consider the chemical stability of the substrate and, consequently, their applicability may be limited. This is of importance for biomedical devices which are composed of multiple classes of materials. Therefore, antifouling methods suitable for whole device modification are highly desirable [1],[2]. An aqueous-based polyethylene glycol (PEG) antifouling coating was previously developed using polydopamine (PDA) as a spacer [1]. PDA has been demonstrated to polymerize strongly onto virtually all material classes and readily forms covalent bonds with free amino groups.[3] However PEG grafting from solution may be sterically limited, leading to areas of exposed PDA available for protein binding. We sought to improve this method by backfilling the PDA-PEG coating with a non cell-adhesive protein, bovine serum albumin (BSA). A previous study on PDA-BSA coated substrates reportedly reduced cell adhesion compared to PDA [4]. We hypothesized that the combination of PEG and BSA may reduce fouling to a greater degree than PEG alone. Materials and Methods: Polydimethyl siloxane (PDMS), hydrophilic porous polycarbonate membranes (PC; 0.01 μm pore diameter), and borosilicate glass cover slips were incubated for 3 h with stirring in 2 mg/mL dopamine solution prepared in PBS, pH 8.5. The PDA coated surfaces were then incubated for 24 h in either (a): 10 mg/mL BSA (PBS, pH 7.4) at room temperature or (b): 5 mg/mL NH2-PEG-NH2 (MW 5000), (PBS, pH 8.5) at 37ºC or (c): (a) followed by (b) or (d): (b) followed by (a). Fibrinogen (Fg) was radiolabeled with I-125 using the ICl method and passed through an ion exchange resin column to remove free iodide. The surfaces were incubated in 1 mg/mL Fg solution in PBS (5% labelled) for 2 h, and rinsed with buffer. Adsorption was quantified from radioactivity measurements. Results and Discussion: Fg was used as a model protein to evaluate resistance to non-specific protein adsorption of the modified PDMS, glass, and PC. Adsorption data are shown in Figure 1. Consistent with previous reports [4], the PDA coated surfaces showed enhanced protein adsorption due to their ability to bind covalently to amino groups in Fg. Compared to the unmodified materials PEG modification was effective in reducing Fg adsorption only on PC. Interestingly, the PDA-PEG modified surfaces showed significantly higher Fg adsorption than the PDA-BSA, possibly due to the larger BSA molecules giving greater surface coverage. For all three substrates there was no significant difference in adsorption between PDA-BSA and PDA-BSA/PEG, possibly due to blockage of PEG attachment by the BSA. The lowest adsorption was seen on the PDA-PEG surfaces that were “backfilled” with BSA. These PDA-PEG/BSA surfaces showed reductions in Fg adsorption of 89%, 63%, and 55% for PC, glass, and PDMS, respectively. Figure 1. Fg adsorption on different substrates. SEM ± mean for n=6 replicates and two trials. Protein concentration = 1 mg/mL. Conclusions: Attachment of passivating moieties to a variety of material types using polydopamine as a bonding agent has been demonstrated. Backfilling PDA-PEG layers with albumin was shown to improve their antifouling properties. The modification was demonstrated on various types of materials, suggesting its utility as a universal antifouling coating. This strategy should be applicable to biomedical devices required to be non-fouling including implants and sensors. Mitacs Globalink; Government of Ontario

Biodegradable Three-Layered Micelles and Injectable Hydrogels.

Polymeric micelles have found a growing interest as gene vectors due to the serious safety concerns associated with viral vectors. In particular, the cationic polymer polyethylene imine (PEI) has shown relatively high condensation and transfection efficiencies. Additionally, polyethylene glycol (PEG) modification of polymeric gene vectors has dramatically improved their biological properties, including enhanced biocompatibility, prolonged circulation time, and increased bio-distribution. However, PEG grafting of PEI for subsequent condensation of nucleic acids (NAs) does not necessarily result in the formation of a PEI/NAs core with a PEG corona. But often times, the presence of PEG interferes with PEI's electrostatic interaction with NAs. We describe here a facile method to prepare multilayered biodegradable micelles which address some of the critical drawbacks associated with current PEI-based systems. The polyplex micelles have superb stability and stealth properties. Moreover, we describe a method to prepare fully biodegradable and biocompatible injectable hydrogels for use in localized gene therapy.

Hyaluronic Acid Modified Hollow Prussian Blue Nanoparticles Loading 10-hydroxycamptothecin for Targeting Thermochemotherapy of Cancer.

This paper reported the fabrication of a multifunctional nanoplatform by modifying hollow Prussian blue nanoparticles with hyaluronic acid grafting polyethylene glycol, followed by loading 10-hydroxycamptothecin for tumor-targeted thermochemotherapy. It was found that the surface modification of hollow Prussian blue nanoparticles with hyaluronic acid grafting polyethylene endowed a great colloidal stability, long blood circulation time and the capability for targeting Hela cells over-expressing the CD44 receptor. The obtained nanoagent exhibited efficient photothermal effect and a light triggered and stepwise release behavior of 10-hydroxycamptothecin due to the strong optical absorption in the near-infrared region. The investigations on the body weight change, histological injury and blood biochemical indexes showed that such nanoagent had excellent biocompatibility for medical application. Both in vitro and in vivo experiments proved that the combination of chemotherapy and photothermal therapy through the agent of hyaluronic acid modified Prussian blue nanoparticles loading 10-hydroxycamptothecin could significantly improve the therapeutic efficacy compared with either therapy alone because of a good synergetic effect.

Antibacterial PLA/PEG electrospun fibers: Comparative study between grafting and blending PEG

Antibacterial micro- and nanofibrous materials based on polylactide (PLA) and polyethylene glycol (PEG) were prepared by electrospinning. PEG incorporation was achieved by its physical blending with or chemical grafting on PLA. The role of the incorporation method on the surface wettability, the thermal, the mechanical and the biological properties was studied in relation to mats applicability. Physical blending or chemical grafting did not significantly modify the wettability of the mats, but showed a plasticizing effect on PLA – more obvious in the case of the physical blend fibers in agreement with the higher PEG mobility. The mechanical properties of the mats were also influenced by the PEG incorporation method. Fibrous mats of physically blended PLA and PEG proved quasi-ductile, while brittle behavior was registered for the chemically grafted poly(l-lactide)-graft-polyethylene glycol methyl ether acrylate mats. 5-nitro-8-hydroxyquinoline (5N8Q) was loaded as a model antibacterial drug. The polyether incorporation method proved influencing the 5N8Q release profile with burst effect recorded for all PEG-containing mats. Additionally, all drug-loaded mats presented antibacterial activity against Staphylococcus aureus and Escherichia coli. Thus, the choice of polyether incorporation method is dependent on the targeted application of the antibacterial materials.