Versatile poly(maltose) micro/nanoparticles with tunable surface functionality as a biomaterial

Maltose, a natural disaccharide, was crosslinked with divinyl sulfone to prepare poly(maltose) (p(MAL)) micro/nanoparticles via one step microemulsion system with ≥90% ± 5% yield in a size rage of 0.5–100 μm for the first time. P(MAL) was modified (m-p(MAL)) with ethylenediamine (EDA), polyethyleneimine (PEI), and taurine (TA) to render additional functionalities, that is, amine and sulfate groups. The isoelectronic point of bare p(MAL) particles were calculated at pH 2.2 ± 0.5 and was changed to 1.3 ± 0.5, 4.3 ± 1.0, and 8.1 ± 0.7 for TA (p(MAL)/TA), EDA (p(MAL)/EDA), and PEI (p(MAL)/PEI) modification, respectively. Bare p(MAL) particles were found to be biocompatible up to 2 mg/ml with hemolysis and blood clotting tests, whereas the modified p(MAL) particles were found to be biocompatible at 1 mg/ml concentration. Additionally, it was found that TA- and PEI-modified p(MAL) particles induced blood clotting mechanisms. Sodium diclofenac as model drug was released at proportions of 8.7% ± 1.3%, 3.9% ± 0.2%, 8.8% ± 0.9%, and 31.6% ± 0.4% of the loaded drug in phosphate buffered saline solution from p(MAL), p(MAL)/TA, p(MAL)/EDA, and p(MAL)/PEI, respectively. The inhibition of antimicrobial activity of p(MAL)/PEI particles at 20 mg/ml concentration for Escherichia coli and Staphylococcus aureus strain was determined as 99.86% ± 0.3% and 99.79% ± 0.25%, respectively.     

Synergistic effects of surface grafting with heparin and addition of poly(d,l-lactide) microparticles on properties of poly(l-lactide) single crystals scaffolds

Mixtures of heparin grafted poly(l- lactide) single crystals (Hep-PLLA_sc) and poly(d ,l- lactide) (PDLLA) microparticles are used for assembling hydrophilic and cytocompatible three-dimensional tissue engineering scaffolds simply by compression molding/salt leaching technique. PLLA is grafted with heparin to promote its surface cytocompatability, while PDLLA is added to reinforce the scaffolds. PLLA_sc are aminolyzed with tetraethylenepentamine (13-atom spacer) to generate sterically accessible amino groups at the surface allowing the covalent attachment of heparin by aqueous carbodiimide chemistry. Morphological and compressive strength studies manifest the integrity and compactness of scaffolds. Toluidine blue assay assures the consistency of heparin distribution throughout the scaffolds, which is in contrary to the conventional grafting reactions by immersing the scaffold in heparin solution. The scaffolds applicability is examined by fibroblast cells seeding experiments. Contrary to pristine scaffolds, Hep-PLLA_sc scaffolds display a hydrophilic and cytocompatible interface for cell adhesion, spreading, growth, and migration. Therefore, combining presurface grafted PLLA_sc with PDLLA microparticles could offer durable scaffolds exhibiting bioactive interface and controllable spatial distribution of the grafted biomacromolecules. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47797.     

Radiopaque iodinated ethers of poly(vinyl iodobenzyl ether)s: Synthesis and evaluation for endovascular embolization

Leachable‐free radiopaque iodinated polymers were designed as long‐lived embolization materials visible by X‐ray tomography. This is a definite improvement over liquid embolics incorporating either radiopaque inorganic particles or iodinated polymers having hydrolysable ester bonds. Grafting 4‐iodobenzyl or 2,3,5‐triiodobenzyl groups to poly(vinyl alcohol) (PVAL) yields iodobenzyl ethers of PVAL having iodine contents in the range 40–70 wt %. Their solubility in solvents accepted for medical devices (DMSO and NMP), viscosity of concentrated solutions, precipitation behavior, radiopacity, and stability with respect to sterilization and hydrolysis were assessed. The solvent NMP allows the preparation of concentrated solutions of suitable viscosity for their application as liquid embolics. Precipitation in water yields a cohesive mass of material that can plug vascular malformations. A rationale to the properties is given in terms of the Hansen contributions to the Hildebrand solubility parameters. Iodobenzyl ethers of PVA resist hydrolysis whereas their corresponding iodobenzoyl esters leach iodinated fragments. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41791.     

Thermosensitive polymeric micelles based on the triblock copolymer poly(d,l‐lactide)‐b‐poly(N‐isopropyl acrylamide)‐b‐poly(d,l‐lactide) for controllable drug delivery

A thermosensitive amphiphilic triblock copolymer, poly(d,l ‐lactide) (PLA)‐b‐poly(N‐isopropyl acrylamide) (PNIPAAM)‐b‐PLA, was synthesized by the ring‐opening polymerization of d,l ‐lactide; the reaction was initiated from a dihydroxy‐terminated poly(N‐isopropyl acrylamide) homopolymer (HO‐PNIPAAM‐OH) created by radical polymerization. The molecular structure, thermosensitive characteristics, and micellization behavior of the obtained triblock copolymer were characterized with Fourier transform infrared spectroscopy, ¹H‐NMR, gel permeation chromatography, dynamic light scattering, and transmission electron microscopy. The obtained results indicate that the composition of PLA‐b‐PNIPAAM‐b‐PLA was in good agreement with what was preconceived. This copolymer could self‐assemble into spherical core–shell micelles (ca. 75–80 nm) in aqueous solution and exhibited a phase‐transition temperature around 26 °C. Furthermore, the drug‐delivery properties of the PLA‐b‐PNIPAAM‐b‐PLA micelles were investigated. The drug‐release test indicated that the synthesized PLA‐b‐PNIPAAM‐b‐PLA micelles could be used as nanocarriers of the anticancer drug adriamycin (ADR) to effectively control the release of the drug. The drug‐delivery properties of PLA‐b‐PNIPAAM‐b‐PLA showed obvious thermosensitive characteristics, and the release time of ADR could be extended to 50 h. This represents a significant improvement from previous PNIPAAM‐based drug‐delivery systems. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45304.     

Synergistic effects of surface aminolysis and hydrolysis on improving fibroblast cell colonization within poly(L-lactide) scaffolds

This work presents a method for overcoming the low internal cell colonization within the tissue engineering scaffolds. 3D scaffolds were fabricated by the compression molding/salt leaching technique from mixtures of aminolyzed and hydrolyzed poly(L-lactide) single crystals (PLLAsc) with poly(D,L-lactide) (PDLLA) microparticles. Modified PLLAsc were used to guarantee the surface hydrophilicity, while PDLLA microparticles were used to reinforce the scaffolds. Mechanical properties, morphology, water uptake and fibroblast cell response of the scaffolds were investigated in comparison with scaffolds from only pristine, hydrolyzed, or aminolyzed PLLAsc. Results showed that the scaffolds exhibited proper morphology and hydrophilicity with an enhanced strength. Water uptake by scaffolds from modified PLLAsc was 1.9 times that from pristine PLLAsc. The scaffolds' compressive moduli increased 2.5 times by using of PDLLA (30 wt%). After cell seeding for a week, the number of cells founded on aminolyzed/hydrolyzed PLLAsc scaffolds were 4.28, 2.14, and 1.36 times that founded for pristine, aminolyzed and hydrolyzed PLLAsc scaffolds, respectively. SEM studies showed that fibroblasts migrated and spread throughout the aminolyzed/hydrolyzed PLLAsc scaffolds better than other scaffolds. Hence, combining both aminolyzed and hydrolyzed PLLAsc with PDLLA could result in a mechanically stable scaffold with an enhanced cell colonization.     

Preparation of poly(divinylbenzene) microspheres with controllable pore structure using poly(propylene)/toluene as coporogen

Poly(divinylbenzene) (poly(DVB)) microspheres with controllable pore structure were synthesized by suspension polymerization in the presence of toluene and low‐molecular weight poly(propylene) (PP) as coporogen. The weight fraction of PP in toluene varied from 0 to 20 wt %, and the feed ratio of coporogen and DVB was kept at 1/1 (vol/vol). Effects of PP weight fraction in coporogen on the specific surface area, the average pore size, the pore size distribution and the total pore volume of final microspheres were examined. As expected, poly(DVB) microspheres prepared with toluene as sole porogen had a high specific surface area (558 m²/g). Using mixtures of toluene and PP as coporogen, it was found that the specific surface area shifted higher values when low levels of PP (2.0–6.0 wt %) in toluene were used as coporogen. However, further increase of PP weight fraction in toluene resulted in progressive decline of the specific surface area. Hg intrusion/extrusion curves and N₂ sorption isotherms implied caged pore structure with some small entrances. Furthermore, most of pore connectivity limitations may be eliminated when the weight fraction of PP in toluene exceeded 10.0 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Studies with gradient polymers of polystyrene and poly(methyl acrylate)

A series of [net-polystyrene]-ipn-[net-poly(methyl acrylate)] systems with gradients of poly(methyl acrylate) in a polystyrene matrix are prepared and tested mechanically. The results showed no distinct differences from that of corresponding interpenetrating polymer network (IPN) samples with similar compositions, in contrast to the substantially improved fracture strains obtained for [net-poly(methyl methacrylate)]-ipn-[-net poly(methyl acrylate)] gradient systems and their nongradient IPN's in our previous work. Hence, it is concluded that the toughening effect of gradient structure observed is not universally applicable for all gradient systems but it is unique for the acrylic system studied. Moduli-temperature responses and dynamic mechanical spectra of gradients and IPN's prepared in the current study are also presented. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1721–1725, 1999     

Antibacterial effect of nanometer-size grafted layer of quaternary ammonium polymer on poly(ether ether ketone) substrate

Owing to its excellent physicochemical properties, poly(ether ether ketone) (PEEK) has been used clinically for medical implants. However, its surface properties should be improved to further enhance its compatibility with a living organism and infection resistance. Here, we examined the surface construction via a combined process, that is, the self-initiated photoinduced graft polymerization of N,N-dimethylaminoethyl methacrylate (DMA) on PEEK substrate followed by polymer quaternization using various bromoalkanes (Q-PDMA-g-PEEK). Using a Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, the grafting and quaternarization of poly(DMA) (PDMA) on the PEEK substrate was confirmed. The degree of quaternizations was at least 60% even when the various bromoalkanes were reacted. The Q-PDMA-g-PEEK with 1-bromooctane (BrC₈) (C₈-Q-PDMA-g-PEEK) substrate exhibited the highest ζ-potential of other Q-PDMA-g-PEEK substrates. However, no significant differences were observed in the degree of quaternization, thickness of the polymer layer, and hydrophilicity of all modified PEEK substrates. In addition, from antibacterial test with Escherichia coli, the C₈Q-PDMA-g-PEEK substrate exhibited the highest antibacterial rate (80%) among Q-PDMA-g-PEEK substrates examined. Therefore, we concluded that the surface ζ-potential is the one an important parameter for manufacturing PEEK substrates with bactericidal properties.     

Comparison of the antibacterial activity of modified‐cotton with magainin I and LL‐37 with potential as wound‐dressings

Wounds are the ideal setting for the development of micro‐organisms, so it is often necessary to apply a dressing to control bacterial colonization. Cotton is commonly used in dressings, as it exhibits important hydrophilic characteristics such as high moisture and fluid retention properties, but it may provide a sustainable media for the development of micro‐organisms. In this way, the development of new strategies to provide cotton materials with lasting and effective antimicrobial properties is of the utmost importance. Consequently, here we described two processes to develop cotton‐dressings functionalized with antimicrobial peptides (AMPs) magainin I (MagI) and LL‐37, in order to give cotton‐dressings an antibacterial effect. The AMPs showed no cytotoxic effect against human fibroblasts so they are safe to contact with skin. In addition, the functionalized materials with either LL‐37 or MagI present an antimicrobial effect exhibiting inhibition ratios of 89% against Klebsiella pneumoniae and 58% against Staphylococcus aureus, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40997.     

Kinetic analysis and improvement of the Williamson reaction for the synthesis of poly(ethylene glycol) propionaldehyde

Poly(ethylene glycol) (PEG) propionaldehyde is an important polymer derivative used in protein modification; it is usually synthesized by the Williamson reaction of 3‐chloropropionaldehyde diethyl acetal (CPADA) with PEG alkoxide followed by hydrolysis to deprotect the aldehyde group. However, the side reaction of the Williamson reaction has been a severe drawback leading to a low‐aldehyde‐content product. In this study, we established a kinetic model to depict the competition of the Williamson reaction and its side reaction. Based on a kinetic analysis, experiments were performed to systemically investigate the influence of the process parameters on the yield of PEG aldehyde, including the reaction solvents, reaction temperature, and molar equivalents of CPADA. The best reaction solvent was determined to be dioxane because the conversion of methoxy pol(ethylene glycol) in dioxane was higher than that in other solvents and because dioxane has low toxicity and is easily handled. The reaction temperature was set as the refluxing point of dioxane to effectively convert PEG into its alkoxide. The equivalents of CPADA were optimized to be 15 to obtain a quantitative yield of mPEG propionaldehyde and avoid wasting the reagent. The quantitative yield of mPEG propionaldehyde was achieved under these optimum conditions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Facile synthesis of amphiphilic chitosan‐g‐poly(lactic acid) derivatives and the study of their controlled drug release

We report here a simple and green procedure for the synthesis of amphiphilic chitosan (CS) derivatives with poly(lactic acid) (PLA) side chains, without the use of high pure lactide, high temperatures, or large amounts of organic solvent. The chemical structure and physical properties of these CS derivatives were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, thermogravimetric analysis, and X‐ray diffraction. The formation and characteristics of polymeric micelles based on these CS derivatives were studied by fluorescence spectroscopy and dynamic light scattering. The critical aggregation concentration in water varied from 0.048 to 0.021 mg/mL, and the mean diameter was in the range 169.8–260.7 nm in aqueous solution at 25°C when the PLA grafting percentage increased from 92 to 132%. Transmission electron microscopy showed that the micelles exhibited a nanospheric morphology within a size range of 60–120 nm. For the resulting micellar aggregates, the drug loading and in vitro drug‐release characteristics were studied with indomethacin as the model drug. We found that such micellar aggregates could be potentially used as nanocarriers for drug delivery. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 908‐915, 2013     

Synthesis,physico-chemical properties and biomedical applications of poly(amidoamine)s

The aim of this article is to provide a comprehensive survey on synthesis, chemical and physico-chemical properties, and applications in several fields, including the biomedical field, of a family of tertiary amino polymers, the poly(amido-amine)s.     

Surface treatment of plasticized poly(vinyl chloride) to prevent plasticizer migration

In this investigation, plasticized poly(vinyl chloride) (PVC) was treated with poly(azido acrylate)s to prevent plasticizer migration. This was achieved by modification of PVC sheets with poly(azido acrylate)s in a dichloromethane solution followed by irradiation under UV light. The surface‐modified PVC sheets with poly (azido acrylate)s were characterized with Fourier transform infrared spectroscopy and scanning electron microscopy analyses. The migration of the plasticizer was prevented to a large extent from modified PVC in comparison with unmodified PVC. The amount of plasticizer migration with respect to the irradiation time, incubation time, and number of dipping times was evaluated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Incorporation of azobenzene chromophore into poly(amide‐imide)

Poly(amide‐imide)s (PAI) bearing azobenzene chromophore groups were prepared by allowing a hydroxyl‐containing azobenzene dye (Disperse Red 1) to react with and reactive‐terminated PAI with weight–average molecular weights ranging from ～ 1.2 to 2.0 × 10⁴ g/mol. Such PAI were prepared by the condensation of trimellitic anhydride (TMA) and 4,4′‐methylene diphenyl diisocyanate (MDI). The final polymers presented a deep red color, with an absorption maxima in N,N‐dimethylformamide (DMF) solution at 490 nm, close to the azobenzene reactant used (Disperse Red 1) and molecular weights slightly higher than the pristine polymer, showing that the azo chromophore incorporation reaction does not lead to side reactions. The azofunctionalized polymer presented a high T_g value (170°C) that could be increased by a thermal curing process to 240°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 841–847, 2007     

Synthesis of carbon quantum dots to fabricate ultraviolet-shielding poly(vinylidene fluoride) films

The paper presents a simple and effective approach to fabricating a poly(vinylidene fluoride) (PVDF) film with excellent ultraviolet (UV) shielding performance. Carbon quantum dots (CQDs) with a highly UV absorbing property were made via a hydrothermal reaction and were then added to a poly(vinyl alcohol) (PVA) solution. The PVDF membrane pretreated with an alkaline solution was immersed in the prepared CQD/PVA solution to coat a UV-shielding layer on the film surface. Fourier transform infrared spectroscopy, X-ray photoelectron spectrometry, X-ray diffraction, transmission electron microscopy, and UV–visible spectrophotometry were applied to study the structure, morphology, and optical performance of the CQD particles. The stability and UV-shielding performance of the obtained PVDF-OH@CQDs/PVA composite film were further investigated. The results showed that the CQD particles with diameter of 18 nm could be well dispersed in solution. Additionally, the CQDs had fairly high UV absorbance, and the PVDF-OH@CQDs/PVA composite film could shield the UV light completely. The method described in this paper is a promising one for fabricating UV-shielding composite films. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47555.     

Thermoresponsive surface prepared by atom transfer radical polymerization directly from poly(vinylidene fluoride) for control of cell adhesion and detachment

Thermoresponsive surface was prepared from commercial poly(vinylidene fluoride) (PVDF) films via surface‐initiated atom transfer radical polymerization. The direct initiation of the secondary fluorinated site of PVDF facilitated grafting of the N‐isopropylacrylamide (NIPAAm) monomer. The PVDF surfaces grafted with poly(N‐isopropylacrylamide) [P(NIPAAm)] were characterized by X‐ray photoelectron spectroscopy. Kinetics study revealed that the P(NIPAAm) chain growth from the PVDF surface was consistent with a “controlled” process. The temperature‐dependent swelling behavior of the surfaces in aqueous solution was studied by atomic force microscope. At 37°C [above the lower critical solution temperature (LCST, about 32°C) of NIPAAm], the seeded cells adhered and spread on the NIPAAm grafted PVDF surface. Below the LCST, the cells detached from the P(NIPAAm)‐grafted PVDF surface spontaneously. The thermoresponsive surfaces are potentially useful as stimuli‐responsive adhesion modifiers in the biomedical fields.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Production and characterization of films containing poly(hydroxybutyrate) (PHB) blended with esterified alginate (ALG‐e) and poly(ethylene glycol) (PEG)

Alternative materials have long been studied and developed to replace conventional skin dressings with the emergence of new biopolymers and development of polymeric film fabrication techniques. As a new material for polymeric dressings, films of poly(hydroxybutyrate) (PHB) blended with esterified alginate (ALG‐e) and poly(ethyleneglycol) was studied. The esterification of sodium alginate (ALG‐e) generated a material with some amphiphilic characteristics and increased compatibility with the PHB. PEG was added as plasticizer in PHB/ALG‐e films was also tested, since PEG is often used in blends with PHB to improve flexibility and reduce hydrophobicity. At the amounts studied, it was found that both PEG and ALG‐e increase the degree of crystallinity, but a decrease was observed in the hydrophobic nature of PHB films. At the maximum concentration of ALG‐e and PEG used an increase in water vapor permeability and a decrease in tensile strength was reached due to the synergistic effect caused by better homogenization of PEG and ALG‐e in the PHB matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44362.     

Effect of interfacial area on heterogeneous free radical grafting of vinyl monomers in supercritical carbon dioxide: Grafting of acrylic acid on poly(vinylidenefluoride) nanoparticles

The role of the polymer interfacial area on free radical grafting of acrylic acid (AA) onto poly(vinylidenefluoride) (PVDF) was studied at 65°C using supercritical carbon dioxide (scCO₂) as a solvent and swelling agent, benzoylperoxide (BPO) as chemical initiator and PVDF nanoparticles as polymer matrix. Under adopted conditions PVDF particles do not melt neither dissolve in the reaction medium and FTIR analyses performed on carefully washed nanoparticles confirmed the achievement of high grafting levels. The mass fraction of grafted AA increased with the grafting time and the BPO concentration while it decreased when the density of the fluid phase was enhanced. Collected results suggest that the grafting level obtained by free radical grafting of vinyl monomers onto solid polymer in scCO₂ can be significantly enhanced by increasing the interfacial area of the matrix. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41541.     

Stabilization of epoxidized soybean oil‐plasticized poly(vinyl chloride) blends via thermal curing with genistein

In an effort to alleviate the well‐known toxicity effect of phthalate derivatives on human health, genistein (G) modified epoxidized soybean oil (ESBO) has been investigated as an alternative “green” plasticizer for poly(vinyl chloride) (PVC) with potential application in medical products. As evidenced by a single glass transition that shifts systematically with composition in conjunction with the melting point depression of G crystals, ESBO is not only a good plasticizer to PVC, but also miscible with G. Moreover, ESBO is an excellent compatibilizer to the immiscible PVC/G pair. Furthermore, PVC/ESBO/G ternary blends revealed complete miscibility in the amorphous state. Of particular interest is that ESBO‐plasticized PVC is thermally curable with G at elevated temperatures above 220 °C and affords relatively stable G modified ESBO‐plasticized PVC for blood contact medical applications such as blood bags and hemodialysis tubings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46472.     

Synthesis of a novel histidine‐targeting poly(ethylene glycol) and modification of lysozyme

A simple and highly efficient method was developed to prepare a synthetic poly(ethylene glycol) (PEG) derivative, which can be used for conjugation to histidine residue. This derivative reacted with sodium nitrite and the intermediate 4‐diazo‐N‐mPEG‐benzamide proved to have a good performance for histidine modification of lysozyme. Then the pegylated lysozyme was separated and its bacteriolytic activities were determined. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011