Grafting of N‐vinyl caprolactam and methacrylic acid onto silicone rubber films for drug‐eluting products

Silicone rubber (SR), a material widely used in the biomedical field, was modified with stimuli‐responsive poly(N‐vinyl caprolactam) (PVCL) and poly(methacrylic acid) (PMAA) with the aim of improving its ability to host drug molecules. The grafting of PVCL and PMAA onto SR was carried out by means of a γ‐ray preirradiation method, and the dependence of the grafting yield on the comonomer concentration, preirradiation dose, temperature, and reaction time was evaluated. Modified SR films were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and swelling studies to confirm the grafting of the copolymer. The SR‐g‐[vinyl caprolactam (VCL)/methacrylic acid (MAA)] copolymers showed a sensitivity to the temperature and pH, high hemocompatibility, and low affinity to bovine serum albumin and fibrinogen proteins. Moreover, the SR‐g‐(VCL/MAA) copolymers were able to host some nonsteroidal anti‐inflammatory drugs, such as diclofenac and ibuprofen, and the antifungal agent nystatin. The graft copolymer was shown to be useful for providing sustained release for several hours; this indicates that the modified SR is a promising material for drug‐eluting medical devices. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41855.     

Development of antimicrobial‐loaded polyurethane films for drug‐eluting catheters

To prepare antibacterial, polymeric catheters for preventing catheter‐induced infections, sulfathiazole was loaded into polyurethane by solubilizing with solvents and the resultant films were cast. Fourier transform infrared spectroscopy confirmed the presence of sulfathiazole in the drug‐loaded polyurethane films. The thermal and mechanical properties of the films were assessed using differential scanning calorimetry and dynamic mechanical analysis. The drug‐loaded films were immersed in constantly stirred, deionized water at 37 °C for in vitro drug release study. The experimental data obtained from the in vitro drug release study were fit into mathematical models. Antibacterial efficiency of released sulfathiazole was evaluated by Escherichia coli growth inhibition test. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46467.     

pH‐sensitive hydroxyethyl starch–doxorubicin conjugates as antitumor prodrugs with enhanced anticancer efficacy

Doxorubicin (DOX) is a widely used chemotherapeutic drug for the treatment of several types of cancers, which has limitation in clinical applications because of severe heart toxicity. Herein, to reduce the fast clearance from the blood system and the severe systemic toxicity caused by the nonspecific protein adsorption, a pH‐sensitive drug delivery system with higher drug conjugated content was prepared by conjugating DOX onto hydroxyethyl starch (HES) with a pH‐sensitive hydrazone bond. In normal physiological environment, the release of DOX conjugated onto HES was slight which could be neglected without any side effect. However, in an acidic environment mimicking the tumor microenvironment, this pH‐sensitive hydrazone linkage provided a controlled and sustained release of DOX over a period of more than 3 days. The conjugates had good biocompatibility, long circulation, and lower cytotoxicity, which could efficiently be transferred into HeLa and HepG2 cells and release the conjugated drug. Based on these promising properties, these HES–DOX conjugates outline the significant potential for future biomedical application in the controlled release of antitumor drugs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42778.     

Synthesis,characterization, and swelling behavior of new pH‐sensitive hydrogels derived from copolymers of 2‐hydroxyethyl methacrylate and 2‐(diisopropylamino)ethylmethacrylate

The aim of this work was to synthesize and to characterize new pH‐sensitive hydrogels that can be used in the controlled release of drugs, useful for dermal treatments or ophthalmology's therapies. Copolymers containing 2‐hydroxyethyl methacrylate (HEMA) with different amounts of 2‐(diisopropylamino)ethyl methacrylate (DPA) (10 and 30 wt %) and different amounts of crosslinker agent, ethylene glycol dimethacrylate (EGDMA) (1 and 3 wt %) were prepared by bulk photo‐polymerization. The copolymers were fully characterized by using Fourier‐transform infrared (FTIR) spectra, differential scanning calorimetry, thermogravimetric analysis, UV–visible spectroscopy, and measuring water content and dynamic swelling degree. The results show that modifications in the amount of DPA and/or crosslinker in the hydrogel produce variations in the thermal properties. When adding of DPA, we observed an increase in the thermal stability and decomposition temperature, as well as a change in the mechanism of decomposition. Also a decrease in the glass transition temperature was observed with regard to the value for pure pHEMA, by the addition of DPA. The water content of the hydrogels depends on the DPA content and it is inversely proportional to both the pH value and the crosslinking degree. Pure poly‐HEMA films did not show important changes over the pH range studied in this work. The dynamic swelling curves show the overshooting effect associated with the incorporation of DPA, the pH of the solution, and the crosslinking density. On the other hand, no important variations in the optical properties were observed. The synthesized hydrogels are useful as a drug delivery pH‐sensitive matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Hollow,pH‐sensitive calcium–alginate/poly(acrylic acid) hydrogel beads as drug carriers for vancomycin release

In this study, hollow calcium–alginate/poly(acrylic acid) (PAA) hydrogel beads were prepared by UV polymerization for use as drug carriers. The hollow structure of the beads was fortified by the incorporation of PAA. The beads exhibited different swelling ratios when immersed in media at different pH values; this demonstrated that the prepared hydrogel beads were pH sensitive. A small amount (<9%) of vancomycin that had been incorporated into the beads was released in simulated gastric fluid, whereas a large amount (≤67%) was released in a sustained manner in simulated intestinal fluid. The observed drug‐release profiles demonstrated that the prepared hydrogel beads are ideal candidate carriers for vancomycin delivery into the gastrointestinal tract. Furthermore, the biological response of cells to these hydrogel beads indicated that they exhibited good biological safety and may have additional applications in tissue engineering. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and swelling behavior of pH‐responsive polyurethane/poly[2‐(diethylamino)ethyl methacrylate] hybrid materials

Polyurethane (PU)/poly[2‐(diethylamino)ethyl methacrylate] hybrids, having a chemical bond between the PU and acrylic moieties and with different compositions, were prepared by the dispersion polymerization of 2‐(diethylamino)ethyl methacrylate (DEA) in the presence of preformed PU chains with polymerizable terminal vinyl groups. The PU dispersion was synthesized according to a prepolymer mixing process by the polyaddition of isophorone diisocyanate, poly(propylene glycol), 2‐hydroxyethyl methacrylate, and dimethylol propionic acid (DMPA). Then, it was dispersed in water by the prior neutralization of the carboxylic acid groups of DMPA with triethylamine, chain‐extended with ethylenediamine. The effect of the DEA content on the swelling properties (water uptake and dynamic swelling degree) at different pHs and at 37°C was determined. The samples were also characterized by Fourier transform infrared spectroscopy and modulated differential scanning calorimetry. The experimental results indicate a higher water uptake when the DEA content was increased on the hybrid materials and a significant change in the kinetics of swelling at pH 4 compared to those at pH 7. The water content of the hydrogels depended on the DEA content, and it was inversely proportional to the pH value. The pure PU film did not show important changes over the pH range examined in this study. The synthesized hybrids were useful as drug‐delivery, pH‐sensitive matrices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39799.     

Preparation and release behavior of temperature‐ and pH‐responsive chitosan material

BACKGROUND: Chitosan is a polymer with good biocompatibility which makes it promising for potential applications in the field of drug delivery. A novel kind of copolymer, P(CS‐Ma‐graft‐NIPAm), was synthesized with chitosan (CS), maleic anhydride (Ma) and N‐isopropylacrylamide (NIPAm) by grafting and copolymerization. RESULTS: The copolymers were characterized using Fourier transform infrared, ¹H NMR and ultraviolet spectroscopies, and the molecular weight and polydispersity were determined using gel permeation chromatography. The aqueous solution properties of the copolymer and the controlled delivery of coenzyme A from it were also studied. The results showed that the copolymer had temperature and pH sensitivities, and that the release of coenzyme A from the copolymer was dependent on the release medium, namely the concentration of the copolymer, pH and temperature. Higher concentrations of the copolymer absorbed more coenzyme A than lower ones. Increasing temperature accelerated coenzyme A release from the copolymer. Also, the pH of the solution had a significant impact on the release of coenzyme A. CONCLUSION: These results suggest that the novel copolymer could be used in drug delivery systems. Copyright © 2007 Society of Chemical Industry     

Drug‐loaded polyurethane/clay nanocomposite nanofibers for topical drug‐delivery application

In this study, polyurethane/nanoclay nanocomposite nanofibrous webs were prepared by electrospinning. An antiseptic drug, chlorhexidine acetate (CA), was loaded onto montmorillonite clay and was then incorporated into polyurethane nanofibers. For comparison, the CA drug was loaded directly into the polyurethane solution dope used to electrospin the nanofibers. The emphasis was on investigating the effect of the drug loading into the nanoclay vis‐à‐vis direct drug loading on the drug‐release behavior of nanofibrous webs. The nanofibrous webs were also evaluated for other properties, such as moisture vapor transmission, porosity determination, contact angle measurement, and antibacterial activity, which are important for topical drug‐delivery application. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40230.     

Development of pH‐sensitive nanogels for cancer treatment using crosslinked poly(aspartic acid‐graft‐imidazole)‐block‐poly(ethylene glycol)

pH‐sensitive nanogels (NGs) based on poly(aspartic acid‐graft‐imidazole)‐poly(ethylene glycol) were developed using linear PEG with different molecular weights (2000 and 4000 Da) as crosslinkers. The pH‐sensitive NGs showed reversible size changes during continuously alternating pH changes. The anticancer treatment potential of pH‐sensitive NGs was studied using a model drug, irinotecan (IRI). IRI‐loaded NGs (ILNs) showed different drug release kinetics in acidic versus neutral pH, in addition to pH‐dependent cytotoxicity. Due to its longer crosslinker, ILN 4 (crosslinked with PEG 4000) showed faster IRI release and a greater magnitude of IRI release than ILN 2 (crosslinked with PEG 2000), resulting in greater cytotoxicity against HCT 116 colorectal cancer cells. These pH‐sensitive NGs could potentially be used in cancer treatment by mediating the accumulation and release of IRI from ILNs in the acidic tumor environment and by reducing systemic toxicity due to reversible swelling–shrinkage. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46268.     

5‐Fluorouracil encapsulated magnetic nanohydrogels for drug‐delivery applications

For the first time, green‐tea (GT)‐based magnetic nanohydrogels were developed for drug‐delivery purposes. The hydrogel matrices were fabricated via the in situ polymerization of acrylamide with GT molecules. Magnetic nanoparticles were synthesized by the reduction of the 1:2 molar ratio mixture of ferrous sulfate heptahydrate and ferric chloride hexahydrate with an ammonia solution. A chemotherapeutic drug, 5‐fluorouracil, was chosen as a model drug, and its releasing profiles in the presence and absence of the external magnetic field were evaluated at a pH of 7.4. We observed that in the presence of the applied magnetic field, these magnetic nanohydrogels released 2.86% more drug than in the absence of a magnetic field. The magnetic nanohydrogels were characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, vibrating sample magnetometry, and transmission electron microscopy. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43921.     

Thermally and magnetically dual‐responsive mesoporous silica nanospheres: preparation,characterization, and properties for the controlled release of sophoridine

Novel thermally and magnetically dual‐responsive mesoporous silica nanoparticles [magnetic mesoporous silica nanospheres (M‐MSNs)–poly(N‐isopropyl acrylamide) (PNIPAAm)] were developed with magnetic iron oxide (Fe₃O₄) nanoparticles as the core, mesoporous silica nanoparticles as the sandwiched layer, and thermally responsive polymers (PNIPAAm) as the outer shell. M‐MSN–PNIPAAm was initially used to control the release of sophoridine. The characteristics of M‐MSN–PNIPAAm were investigated by transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetry, N₂ adsorption–desorption isotherms, and vibrating specimen magnetometry analyses. The results indicate that the Fe₃O₄ nanoparticles were incorporated into the M‐MSNs, and PNIPAAm was grafted onto the surface of the M‐MSNs via precipitation polymerization. The obtained M‐MSN–PNIPAAm possessed superparamagnetic characteristics with a high surface area (292.44 m²/g), large pore volume (0.246 mL/g), and large mesoporous pore size (2.18 nm). Sophoridine was used as a drug model to investigate the loading and release properties at different temperatures. The results demonstrate that the PNIPAAm layers on the surface of M‐MSN–PNIPAAm effectively regulated the uptake and release of sophoridine. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40477.     

6‐O‐dodecyl‐chitosan carbamate–based pH‐responsive polymeric micelles for gene delivery

pH‐responsiveness is highly desirable in the stimuli‐responsive controlled release because of the distinct advantages of the fast response of pH‐triggered release and the available pH‐difference between intra‐ and extra‐cells. The present work reported a kind of novel pH‐responsive polymeric micelles, which was derived from biopolymer of 6‐O‐dodecyl‐chitosan carbamate (DCC) and evaluated as gene‐controlled release vector. The amphiphilic and amino‐rich DDC was synthesized through a protection‐graft‐deprotection method. ¹³C CP/MAS NMR, FTIR, and elemental analysis identified that dodecyls were chemoselectively grafting at 6‐hydroxyls of chitosan via the pH‐responsive bonds of carbamate, and the substitute degree (SD) was 14%. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) showed that DCC self‐assembled into polymeric micelles in aqueous solutions. The DCC polymeric micelles formed complexes with pDNA, which was elucidated by Gel retardation, TEM, and DLS. Transfection and cytotoxicity assays in A549 cells showed that DCC polymeric micelles were suitable for gene delivery. The improved transfection was attributed to the pH‐responsiveness and the moderate pDNA‐binding affinity, which led to easier release of pDNA intra‐cells. The synthesized DCC polymeric micelles might be a promising and safe candidate as nonviral vectors for gene delivery. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42469.     

A convenient scheme for synthesizing reduction‐sensitive chitosan‐based amphiphilic copolymers for drug delivery

A novel type of reduction‐sensitive graft copolymers, chitosan‐S‐S‐poly(ε‐caprolactone) (CS‐S‐S‐PCL, here ‐S‐S‐ means PCL was conjugated onto chitosan backbone through disulfide linkage), was synthesized through a convenient route using dithiodipropionic anhydride (DTDPA) as a disulfide donor. Reaction of hydroxy‐terminated poly(ε‐caprolactone) (PCL) with DTDPA quantitatively yielded DTDPA functionalized PCL (PCL‐S‐S‐COOH). The disulfide‐containing polyester was regioselectively conjugated onto the hydroxy groups of chitosan under mild and homogeneous conditions, utilizing dodecyl sulfate‐chitosan complexes (SCC) as an intermediate. The self‐assembly and Doxorubicin (Dox) release behavior of the copolymers were investigated. Spherical micelles could be formed through self‐assembly of CS‐S‐S‐PCL in aqueous media. The reduction‐sensitive behavior of CS‐S‐S‐PCL micelles was investigated by using Dithiothreitol (DTT) as a reductive reagent. In the presence of 10 mM DTT, the micelles gradually lost their aggregation stability and were precipitated out after four days. In addition, the Dox release was accelerated when the micelles were treated with DTT. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of a novel pH‐sensitive polyurethane–alginate blend with poly(ethylene terephthalate) waste for the oral delivery of protein

With the aim of using poly(ethylene terephthalate) (PET) waste for the synthesis of a value added product, we prepared polyurethane (PU) from bishydrohxyethylene terephthalate (BHET), a byproduct obtained from the glycolysis of PET. Biodegradable, water‐swelling PU was synthesized by the reaction of BHET, hexamethylene diisocyanate, and poly(ethylene glycol) (PEG). Both BHET and PU were characterized by Fourier transform infrared spectroscopy, and the formation of PU was further confirmed by NMR analysis. The swelling behavior of PU in water was examined in terms of the various molecular weights of PEG. Semi‐interpenetrating network beads of PU and sodium alginate were prepared with calcium chloride (CaCl₂) as a crosslinker to attain a pH sensitivity for successful oral protein/drug delivery. Bovine serum albumin (BSA) was used as a model protein. The pH‐responsive swelling behavior and protein (BSA) release kinetics in different pH media corresponding to the gastrointestinal tract (pH 1.2 and 7.4) were investigated. The degree of swelling in the case of the PU–alginate beads at pH 1.2 was found to be at a minimum, whereas the degree of swelling was significantly elevated (1080%) at pH 7.4. This substantiated the pH sensitivity of the polymeric beads with a minimum loss of encapsulated protein in the stomach and the almost complete release of encapsulated protein in the intestine. This revealed good opportunities for oral protein/drug delivery with a polymer derived from waste PET. Moreover, the fungal biodegradation study confirmed its compatibility with the ecological system. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40650.     

Fabrication of pH‐sensitive poly(2‐(diethylamino)ethyl methacrylate)/palygorskite composite microspheres via Pickering emulsion polymerization and their release behavior

The poly(2‐(diethylamino)ethyl methacrylate)/palygorskite (PDEAEMA/PAL) composite microspheres were prepared via Pickering emulsion polymerization using palygorskite (PAL) as an emulsifier. The morphology, chemical structure, and content of PDEAEMA/PAL composite microspheres were investigated by polarizing optical microscopy, scanning electron microscopy (SEM), Fourier‐transform infrared (FT‐IR) spectroscopy, and thermal gravimetric analysis (TGA). The pH‐responsive behavior of composite microspheres was studied by measuring their size at different pH values. Furthermore, their release behavior was investigated using rhodamine B (RhB) as a model molecule. It was proven that the release properties of RhB from PDEAEMA/PAL composite microspheres could be controlled by adjusting the pH values. The study of release kinetics found that Higuchi model was fit for RhB release from PDEAEMA/PAL composite microspheres at pH 5.0, 7.4, and 10.0. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42179.     

Synthesis of pH‐responsive polyethylene terephthalate track‐etched membranes by grafting hydroxyethyl‐methacrylate using atom‐transfer radical polymerization method

pH‐responsive polyethylene terephthalate (PET) track‐etched membranes were synthesized by grafting 2‐hydroxyethyl‐methacrylate (HEMA) on the surface of the membrane via atom transfer radical polymerization. The controllability of grafting polymerization of HEMA on membrane surface is systematically investigated. The pH‐responsive characteristics of PET‐g‐poly(2‐hydroxyethyl‐methacrylate) (PHEMA) gating membranes with different grafted PHEMA chain lengths are measured by tracking the permeation of water solution with different pH values. The results show that the grafting polymerization is controllable, and the permeation of grafted membranes is affected by the grafted PHEMA chain lengths on the surface of membrane. The results also demonstrate that the grafted PET membranes exhibit reversible pH‐response permeation to environmental pH values. Desired pH‐responsive membranes are obtained by controlling the grafted PHEMA chain lengths via atom transfer radical polymerization method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40912.     

Synthesis,characterization, and drug‐release behavior of amphiphilic quaternary ammonium chitosan derivatives

A new type of amphiphilic quaternary ammonium chitosan derivative, 2‐N‐carboxymethyl‐6‐O‐diethylaminoethyl chitosan (DEAE–CMC), was synthesized through a two‐step Schiff base reaction process and applied to drug delivery. In the first step, benzaldehyde was used as a protective agent for the incorporation of diethylaminoethyl groups to form the intermediate (6‐O‐diethylaminoethyl chitosan). On the other hand, NaBH₄ was used as a reducing agent to reduce the Schiff base, which was generated by glyoxylic acid, for the further incorporation of carboxymethyl groups to produce DEAE–CMC. The structure, thermal properties, surface morphology, and diameter distribution of the resulting chitosan graft copolymers were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, thermogravimetric analysis, differential scanning calorimetry, X‐ray powder diffraction, scanning electron microscopy, and laser particle size analysis. Benefiting from the amphiphilic structure, DEAE–CMC was able to be formed into microspheres in aqueous solution with an average diameter of 4.52 ± 1.21 μm. An in vitro evaluation of these microspheres demonstrated their efficient controlled release behavior of a drug. The accumulated release ratio of vitamin B₁₂ loaded DEAE–CMC microspheres were up to 93%, and the duration was up to 15 h. The grafted polymers of DEAE–CMC were found to be blood‐compatible, and no cytotoxic effect was shown in human SiHa cells in an MTT [3‐(4, 5‐dimethyl‐thiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide] cytotoxicity assay. These results indicate that the DEAE–CMC microspheres could be used as safe, promising drug‐delivery systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39890.     

Drug‐loaded microparticles prepared by the one‐step deposition of calcium carbonate/alginate onto cotton fabrics

Calcium carbonate (CaCO₃)/alginate inorganic–organic hybrid particles were synthesized and deposited on to the surface of cotton fabrics with a novel one‐step procedure. The effects of the Ca²⁺/CO₃^2?/alginate molar ratio on the cotton matrix were investigated. The optimization of the process resulted in a regular shaped hybrid microparticles, and scanning electron microscopy revealed that the particles were uniformly distributed on the surface of the fibers. Dynamic light scattering showed that the particles were about 2 μm in diameter. Moreover, transmission electron microscopy images demonstrated that the core–shell structure of the particles existed along with CaCO₃ evenly enfolded into the alginate layer. An X‐ray diffraction pattern displayed that the alginate/CaCO₃ hybrid microparticles were a mixture of calcite and vaterite crystal. Fourier transform infrared spectroscopy indicated that CaCO₃/alginate hybrid particles formed in situ were the only deposited materials. The thermogravimetric analysis curve indicated a certain mass ratio of the alginate and CaCO₃ in the hybrid particles. Furthermore, the drug‐loading and drug‐release properties of the hybrid microspheres were studied, and the results show that the water‐soluble diclofenac sodium could be effectively loaded in the hybrid microparticles and the drug release could be effectively sustained. Finally, both of the microparticles and modified fabrics had good cytocompatibility. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42618.     

Synergistic effect and drug‐resistance relief of paclitaxel and cisplatin caused by Co‐delivery using polymeric micelles

Combination therapy of paclitaxel (PTX) and cisplatin has been used to treat several cancers in clinic practice, but often causes serious systemic toxicity. Co‐delivery of PTX and cisplatin by means of polymeric micelles can reduce the systemic toxicity, but often needs two carrier polymers because of the solubility difference between them. Therefore, a strategy is developed to co‐deliver both PTX and cisplatin with only one carrier polymer by encapsulating PTX in the core of a polymeric micelle and cross‐linking the micelle with cisplatin. The PTX and Pt contents in the micellar formulation M(PTX/Pt) were 10 and 14 wt %, respectively. In vitro cytotoxicity of M(PTX/Pt) was evaluated via 3‐(4,5‐dimethylthiazol‐2‐yl)?2,5‐diphenyltetrazolium bromide assay in comparison with PTX and its micelle M(PTX), cisplatin and its micelle M(Pt), and PTX/cisplatin combination towards human hepatocarcinoma (SMMC‐7721) cells and chemoresistant SMMC‐7721(SMMC‐7721R) cells. The M(PTX/Pt) exhibited a high synergistic effect in the inhibition of cell growth and proliferation of both SMMC‐7721 and SMMC‐7721R cells and showed reasonable drug‐resistance relief. The synergistic effect and resistance relief were further supported or explained by intracellular uptake measurement of dye‐labeled micelles and by the confocal laser scanning microscopy observation of SMMC‐7721 and SMMC‐7721R cells treated with various formulations. Therefore, M(PTX/Pt) micelles were expected to find potential application in cancer chemotherapy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41440.     

Layer‐by‐layer assembly of poly(allylamine hydrochloride)/polyurethane and its loading and release behavior for methylene orange

Here, layer‐by‐layer technique was used for sequential adsorption of oppositely charged polymer poly(allylamine hydrochloride) (PAH) and polyurethane (PU) through electrostatic interaction. 10 and 10.5 bilayer films were prepared separately, methylene orange (MO) was used as a model drug to evaluate the potential ability of this multilayer film used in drug delivery system. Experimental results showed the ability of loading and release of MO from the film was significantly influenced by pH and salt concentration, the loading rate of MO was faster and larger with increasing salt concentration or decreasing pH of MO solution, the release rate of MO was faster at higher salt concentration or in alkali solution. The result also indicated that the film had a good reversibility of loading and release. PAH/PU film could be a promising drug delivery system because of its biocompatibility, biodegradation and above properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013