6-O-carboxymethyl-chitin (CM-chitin) as a drug carrier

Gel was prepared from 6-O-carboxymethyl-chitin (CM-chitin) by the addition of iron(III) chloride under mild conditions without any organic solvent. The optimal conditions for the gel formation were 15 to 30 mM iron(III) chloride and 0.5 to 0.8 degree of substitution in CM-chitin. The amounts of bovine serum albumin (BSA) and the anticancer drug doxorubicin (DOX) incorporated into CM-chitin gels were more than 80% and 30%, respectively under the conditions described above. The release of BSA or DOX from the gels was observed to be increased by lysozyme digestion in a time-dependent manner. This result indicates that CM-chitin might prove useful as a carrier gel for the sustained release of drugs and cytokines, including vaccines.     

Synthesis of a hemostatic drug from cellulose acetate

Hemostatic resorbent polymeric materials have been synthesized from water-soluble acetylcellulose, lagochilin, and lagohirsin. The substances obtained possess an effective hemostatic action and have a water-soluble form.Tashkent Institute of Chemical Technology. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 238–241, March–April, 1998.     

Transparent polymer blends composed of cellulose acetate propionate and poly(epichlorohydrin)

Structure and properties for binary blends composed of biomass-based cellulose acetate propionate (CAP) and poly(epichlorohydrin) (PECH) have been studied. It is found from the dynamic mechanical measurements that mutual dissolution takes place to some degree with remaining CAP-rich and PECH-rich regions in the blends. As a result of the interdiffusion, leading to fine morphology, the blends exhibit high level of optical transparency although the individual pure components have different refractive index. Furthermore, the mechanical toughness of CAP, which is one of the most serious problems for CAP, is considerably improved by blending PECH. This will have a great impact on industries because the blend technique widens the application of CAP.     

Electrospun cellulose acetate/poly(vinylidene fluoride) nanofibrous membrane for polymer lithium-ion batteries

The membranes for gel polymer electrolyte (GPE) for lithium-ion batteries were prepared by electrospinning a blend of poly(vinylidene fluoride) (PVdF) with cellulose acetate (CA). The performances of the prepared membranes and the resulted GPEs were investigated, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), porosity, hydrophilicity, electrolyte uptake, mechanical property, thermal stability, AC impedance measurements, linear sweep voltammetry, and charge–discharge cycle tests. The effect of the ratio of CA to PVdF on the performance of the prepared membranes was considered. It is found that the GPE based on the blended polymer with CA:PVdF =2:8 (in weight) has an outstanding combination property-strength (11.1 MPa), electrolyte uptake (768.2 %), thermal stability (no shrinkage under 80 °C without tension), and ionic conductivity (2.61 × 10^?3 S cm^?1). The Li/GPE/LiCoO₂ battery using this GPE exhibits superior cyclic stability and storage performance at room temperature. Its specific capacity reaches up to 204.15 mAh g^?1, with embedded lithium capacity utilization rate of 74.94 %, which is higher than the other lithium-ion batteries with the same cathode material LiCoO₂ (about 50 %).     

Dioxouranium (VI) complexes with cellulose acetate

Dioxouranium [UO₂(VI)] complexes with three degrees of substitution of cellulose acetate, prepared from viscose pulp (DS = 2.2, 2.45 and 2.86), have been synthesis and characterized. Degree of substitution (DS) is defined as the average number of CH groups substituted on each anhydrocellulose repeat unit. Probable structures of the cellulose acetate complexes were inferred from the elemental analysis data, conductance measurements, IR, electronic and ¹H NMR spectra. The results obtained show that the formula of UO₂(VI) complex with cellulose acetate of DS = 2.2 and 2.45 [(CA)₄.UO₂] is more probable than [(CA)₂.UO₂].2(CH₃COO), while the reverse is true for the case of a UO₂ complex with CA of DS = 2.86. For the former formula, cellulose acetate acts as a uni-negatively charged bidentate ligand and reacts with UO₂²⁺ through the ether-carbon-oxygen of the secondary acetylated hydroxyl group of the anhydroglucose unit and the oxygen atom of the residual secondary unacetylated hydroxyl group, forming a five-membered chelate ring. For the later formula, cellulose acetate of DS = 2.86 acts as a neutral bidentate chelating agent through the two ether oxygen atoms of the vicinal ester groups of secondary acetylated hydroxyl groups in anhydroglucose units also forming a five-membered chelate ring. The uranium atom in these complexes is 8-coordinate. The thermal behaviour of cellulose diacetate (DS = 2.2) and cellulose triacetate (DS = 2.86) and their complexes with uranyl acetate in nitrogen atmosphere has been also studied by differential thermal analysis from room temperature to 600 °C. The obtained DTA curves were analyzed using the Prout-Tompkins law. The method of least squares was applied to estimate the appropriate order of the reaction (n), and consequently the thermodynamic parameters. The results revealed that chelation of cellulose acetate with uranyl acetate led to increased thermal stability.     

Uphill transport of acetate anion through synthetic polymer membranes with pyridinium cations as fixed carrier

Acetate anion was transported against its concentration gradient through a synthetic polymer membrane with pyridinium cation units as fixed carrier. Two synthetic membrane materials were studied, poly(1-butyl-4-vinylpyridinium iodide-co-acrylonitrile) and poly(1-methyl-4-vinylpyridinium iodide-co-acrylonitrile). Acetate anion was transported by an antiport mechanism, with halogen ion transfer as driving force.     

Zero-order drug release cellulose acetate nanofibers prepared using coaxial electrospinning

Novel drug-loaded cellulose acetate (CA) nanofibres were prepared by a modified coaxial electrospinning process, after which their zero-order drug release profiles were determined. Using 2 % (w/v) unspinnable CA solution as a sheath fluid, coaxial electrospinning can be conducted smoothly to generate ketoprofen (KET)-loaded CA nanofibres coated with a thin layer of blank CA. Scanning electron microscopy images demonstrated that nanofibres obtained from the modified coaxial process have a smaller average diameter, a narrower size distribution, more uniform structures, and smoother surface morphologies than those generated from single-fluid electrospinning. Transmission electron microscopy observations demonstrated that the nanofibres have a thin coating layer of blank CA on their surface with a thickness of ca. 15 nm. X-ray diffraction and differential scanning calorimetry verified that KET molecules in all of the nanofibres presented an amorphous state. Fourier transform infrared spectra demonstrated that CA has good compatibility with KET, which is brought about by hydrogen bonding. In vitro dissolution tests showed that the nanofibres coated with blank CA have no initial burst release effects and can provide a zero-order drug release profile over 96 h via a diffusion mechanism. The modified coaxial electrospinning method can provide new approaches in developing cellulose-based nano products with definite structural characteristics and improved functional performance.     

Application of cellulose acetate butyrate-based membrane for osmotic drug delivery

The release rate of drugs from an OROS^® is controlled by semipermeable membranes composed typically of cellulose acetate (CA) with various flux enhancers. Cellulose acetate butyrate (CAB) was identified as a viable alternative. The CAB membrane matched the CA membrane in robustness but had superior drying properties, offering particular advantages for thermolabile formulations. Studies were conducted to characterize CAB membrane properties with respect to performance of OROS^® systems. Four different membrane formulations with varying plasticizer type and concentration were investigated. The CAB based membranes exhibited superior drying characteristics and similar functionality to the CA:polyethylene glycol (PEG) membranes used as a control. A linear relationship was observed between the level of flux enhancer and release rate. The stability of the membrane was evaluated based on release profiles after system storage at various conditions. The CAB membranes appeared to have stability comparable to the standard CA membrane. A linear relationship between membrane weight and release rate as well as the time required to release 90% of a drug from the system [T₉₀] for a model formulation was observed. In conclusion, the newly identified alternative membrane composition allows for the use of thinner membranes, thereby reducing cost of goods, coating time and, most importantly, membrane drying time.     

Controlled release of drug via tuning electrospun polymer carrier

Medicated‐fibers have been obtained through electrospinning after rifampin was dissolved in poly (lactic acid)/chloroform solution. The relationship between polymer variables [such as concentration, molecular weight (M_w), and introducing hydrophilic block] and drug release from the electrospun fibers is disclosed. The results show that polymeric concentration and M_w are crucial for producing the medicated fibers, which influence not only the morphology of the medicated‐fiber but also drug release rate from fiber. At the same M_w, the drug release rate decreases with the increase of spinning concentration. At two different M_w blends, drug release behaviors change. When the low M_w content is in a dominant position, drug release rate depends largely on mixing ratio of two M_w contents; on the other hand, drug release rate is also dependent on concentration of spinning fluid. In addition, the block copolymer [poly‐L ‐lactic acid (PLLA)‐polyethylene glycol‐PLLA] shows faster release rate as compared to homopolymer (PLLA). © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Birefringence control for binary blends of cellulose acetate propionate and poly(vinyl acetate)

Structure and optical properties for binary blends composed of biomass-based cellulose acetate propionate (CAP) and poly(vinyl acetate) (PVAc) have been studied. It is found that the blends exhibit high level of transparency, although the dynamic mechanical analysis in the solid state suggests that phase separation occurs in the blend. Furthermore, the birefringence resulting from molecular orientation decreases with increasing the content of PVAc. In particular, the blend with approximately 50 wt% of PVAc exhibits no birefringence even after stretching.     

Radiation synthesis of acrylic acid/polyethyleneimine interpenetrating polymer networks (IPNs) hydrogels and its application as a carrier of atorvastatin drug for controlling cholesterol

Gamma irradiation was used to form interpenetrating polymer networks structure (IPNs) hydrogels based on different ratios of acrylic acid monomer (AAc) and polyethyleneimine (PEI). The property-behavior was characterized by IR spectroscopy, gel content, thermogravimetric analysis (TGA) and swelling in water at room temperature and different pH values. The AAc/PEI hydrogels were used as a carrier for atorvastatin drug, in which the uptake-release character was studied. The results showed that the gel content of AAc/PEI hydrogels decreased greatly with increasing the ratio of PEI in the initial feeding solution. The AAc/PEI hydrogels displayed pH-sensitive character. The drug uptake-release study indicated that AAc/PEI hydrogels possessed controlled release behavior and that the release process depends on pH. In this respect, the release of atorvastatin drug was significant in acidic medium.     

Novel cellulose acetate membrane blended with phospholipid polymer for hemocompatible filtration system

To improve the blood compatibility of cellulose acetate (CA) membranes for hemofiltration, a novel CA membrane blended with 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer was designed for a hemocompatible filtration system. The MPC copolymer (PMB30) was synthesized from MPC and n-butyl methacrylate. The polymer solution for making the membrane was prepared from a solvent mixture composed of N,N-dimethylformamide, acetone, and 2-propanol. The CA and CA/PMB30 blended membranes with an asymmetric and porous structure were prepared by a phase inversion process. The mechanical properties and solute permeability of the CA/PMB30 blended membrane could be controlled by preparation conditions such as the composition of the solvents and the solvent evaporation time. The CA/PMB30 blended membrane showed both good water and solute permeabilities in comparison with the CA membrane. Also, the molecular weight of the solute passed through the membrane was changed by the addition of PMB30, and good permselectivity could be obtained. Moreover, the CA/PMB30 blended membranes had excellent blood compatibility such as protein adsorption resistivity compared to the CA membrane due to location of the MPC units in the PMB30 at the surface.     

3-Diethylaminopropyl-bearing glycol chitosan as a protein drug carrier

Polysaccharidic nanogels were fabricated with bovine serum albumin (BSA) and a glycol chitosan (GCS) grafted with functional 3-diethylaminopropyl (DEAP) groups. These nanogels were investigated to evaluate their cellular uptake in HeLa cells and in vivo fate in nude mice tumor model. Unlike free BSA, GCS-g-DEAP/BSA nanogels improved cellular uptake of BSA. Furthermore, this system led to an enhanced blood circulation and a high accumulation of BSA in the tumor site. Our collective results strongly support that GCS-g-DEAP/BSA nanogel is a potential carrier system for high molecular weight proteins.     

Tunable self-assembled stereocomplexed-polylactic acid nanoparticles as a drug carrier

In this study, a model hydrophilic drug (porphyrin) was encapsulated within hydrophobic polylactic acid (PLA) nanoparticles (NPs) with different crystallinity and the relevant release behaviors were investigated. The crystalline modification was done using a modified nanoprecipitation method, where homo and stereocomplexed PLA NPs with different average diameters based on varying polymer concentrations and solvent/nonsolvent ratios (S/N) were prepared. Entrapment efficiency and drug release of sterocomplexed-PLA NPs were compared with neat poly(l -lactic acid) (PLLA) NPs. Furthermore, to get the more sustained release, porphyrin-loaded NPs were immobilized within electrospun poly(d ,l -lactide-co-glycolide (PLGA) nanofibers (NFs). Outcomes revealed that solution concentration and solvent/nonsolvent ratio play significant roles in the formation of homo and stereocomplexed NPs. On the other hand, it was found that the formation of stereocrystals did not significantly affect the size and morphology of NPs compared with neat NPs. With regard to the entrapment efficiency and drug content, stereocomplexd-PLA NPs behave relatively the same as neat PLLA NPs while the more sustained release was observed for stereocomplexed NPs. Also, it was observed that electrospinning of PLGA solution loaded by NPs led to the uniform distribution of NPs into PLGA fibers. Encapsulating the drug-loaded NPs into nanofibers decreased the rate of drug release by 50% after 24 h, compared with direct loading of drug into PLGA NFs. We conclude that it is possible to tune the entrapment efficiency and modify the release rate of the drug by giving small changes in the process parameters without altering the physical properties of the original drug substance and polymer.     

Tetrakis(4-N,N-dimethylaminobenzene)porphyrinato]manganese(III) acetate as a novel carrier for a selective iodide PVC membrane electrode.

[5,10,15,20-Tetrakis(4-N,N-dimethylaminobenzene)porphyrinato]Mn(III) acetate (MnTDPAc) was applied as an ionophore for an iodide-selective PVC membrane electrode. The influences of the membrane composition, pH of the test solution and foreign ions on the electrode performance were investigated. The sensor exhibited not only excellent selectivity to iodide ion compared to Cl- and lipophilic anions such as ClO4- and salicylate, but also a Nernstian response with a slope of -59.4 +/- 1.2 mV per decade for iodide ions over a wide concentration range from 1.0 x 10(-2) to 7.5 x 10(-6) M at 25 degrees C. The potentiometric response was independent of the pH of the solution in the pH range of 2 - 8. The electrode could be used for at least 2 months without any considerable divergence in the potential. Good selectivity for iodide ion, a very short response time, simple preparation and relatively long-term stability were the silent characteristics of this electrode. It was successfully used as an indicator electrode in the potentiometric titration of iodide ions, and also in the determination of iodide from seawater samples and drug formulations.     

Molecular (osmotic and electro-osmotic) backwash of cellulose acetate hyperfiltration membranes

A technique using osmosis and/or electro-osmosis was developed to clean and possibly decompact contaminated modified (asymmetric)cellulose acetate membranes. p]The rejuvenation technique developed is called “molecular backwash”. When contaminated with ferric hydroxide, the membranes (cured at 92°C) exhibited considerable flux decrease. After molecular backwashing, the hyperfiltration flux increased again. In some cases, molecular backwash also partially restored the salt rejection loss which had occurred during contamination. Flux loss recovered by molecular backwashing varied from 30% to over 100% (i.e. the flux of the compacted membrane was greater than before contamination, but not greater than the flux of a clean uncompacted membrane).     

Interactions underpinning the plasticization of a polymer matrix: a dynamic and structural analysis of DMP-plasticized cellulose acetate

This work establishes that the plasticization effect of a classical petrochemical plasticizer, dimethyl phthalate (DMP), on a polymer matrix, cellulose acetate (CA), is due to the development of intermolecular interactions of dipolar type. Plasticized cellulose acetate films are studied with regard to the interactions between the polymer and plasticizer at the macroscopic scale by thermogravimetric analysis and differential scanning calorimetry. At the molecular level, Fourier transform infrared spectroscopy and dielectric relaxation spectroscopy are used to elucidate the nature of interactions that are responsible for the plasticizing effects. These static and dynamic complementary analyses evidenced that DMP does not establish H-bonding interactions with the polymer chains of cellulose acetate but rather weaker interactions of dipolar type. These dipole–dipole interactions that develop between acetyl side groups of CA and the ester phthalate moieties of DMP increase the overall mobility of CA chains and also locally influence the molecular mobility and the water uptake tendency.     

DNA origami as a carrier for circumvention of drug resistance

Although a multitude of promising anti-cancer drugs have been developed over the past 50 years, effective delivery of the drugs to diseased cells remains a challenge. Recently, nanoparticles have been used as drug delivery vehicles due to their high delivery efficiencies and the possibility to circumvent cellular drug resistance. However, the lack of biocompatibility and inability to engineer spatially addressable surfaces for multi-functional activity remains an obstacle to their widespread use. Here we present a novel drug carrier system based on self-assembled, spatially addressable DNA origami nanostructures that confronts these limitations. Doxorubicin, a well-known anti-cancer drug, was non-covalently attached to DNA origami nanostructures through intercalation. A high level of drug loading efficiency was achieved, and the complex exhibited prominent cytotoxicity not only to regular human breast adenocarcinoma cancer cells (MCF?7), but more importantly to doxorubicin-resistant cancer cells, inducing a remarkable reversal of phenotype resistance. With the DNA origami drug delivery vehicles, the cellular internalization of doxorubicin was increased, which contributed to the significant enhancement of cell-killing activity to doxorubicin-resistant MCF?7 cells. Presumably, the activity of doxorubicin-loaded DNA origami inhibits lysosomal acidification, resulting in cellular redistribution of the drug to action sites. Our results suggest that DNA origami has immense potential as an efficient, biocompatible drug carrier and delivery vehicle in the treatment of cancer.     

Molecular and crystal structure of cellulose acetate dipropanoate (CADP, 6-O-acetyl-2,3-di-O-propanoyl cellulose)

The molecular and crystal structure of cellulose acetate dipropanoate (CADP, 6-O-acetyl-2,3-di O-propanoyl cellulose) has been determined by using a constrained linked-atom least-squares refinement method, combined with X-ray and electron diffractograms and stereochemical refinement. The diffraction analysis indicated that CADP crystallized in a P2 ₁ monoclinic space group with unit cell parameters:a =1.088 nm,b (unique axis)=1.593 nm,c (fibre axis)=1.509 nm and =94.1°. The best model derived from combining the stereochemical refinement with the diffraction intensities gave R=0.217 (R=0.195) for the three-dimensional information from the X-ray fibre diagram and R=0.198 for the base plane data resulting from electron diffraction analysis. In the model, the crystal structure of CADP consisted of a system of right-handed threefold helices packed in an antiparallel fashion, with two molecules passing through the unit cell.