Release profiles of indometacin in <Emphasis Type="Italic">β</Emphasis>-cyclodextrin complexes from HPMC capsules

Powders containing indometacin complexed with β-cyclodextrin (1:1 ratio) obtained by two complexation methods (suspension/solution [with water removed by air stream, spray– and freeze–drying] and kneading techniques) were compared between them to observe the increase on the drug solubility and yield of the complexation process. The tests used for this comparison included the determination of the moisture content, true and bulk densities, angle of repose, Carr’s index and in vitro drug release (at pH 1.0) from HPMC capsules. In the dissolution tests the drug release was analyzed considering different parameters (similarity factor (f ₂), dissolution efficiency (DE) and the amounts released (M _t) at certain times (30, 60 and 180 min) by statistic analysis (α = 0.05)). The results obtained showed poor pharmaceutical properties for all mixtures and that the indometacin released from capsules containing inclusion complexes presented an increase on solubility when compared with reference formulation (lactose and microcrystalline cellulose instead of β-cyclodextrin). The release of indometacin showed no dependency on the amount of water used in the formation of the complexes being the differences observed mostly due to the characteristics of the particles, which were dependent on the complexation method. However the low yield of the complexation that occurred can be explained by the difference between the size of the drug molecule, the guest (diameter—7.5 Å, length—14.2 Å) and the size of the β-cyclodextrin cavity, the host (diameter—6.0–6.5 Å).     

Effect of magnetic field on phase transitions in solutions and melts of flexible polymers

The effect of the magnetic field on the phase diagrams of flexible-chain polymer–solvent systems is observed for the first time. Phase transitions in systems with the crystalline-phase separation (PE–o-xylene, PE–n-hexane, PE–chloroform, PE–o-dichlorobenzene, PEG–1,4-dioxane, PEG–toluene) and the amorphous demixing (PS–methyl acetate, PVA–ethanol, PDMS–butanone) are studied. The magnetic field increases the temperatures of crystallization of PE and PEG from solutions and melts but has no effect on phase transitions in PS, PVA, and PDMS solutions. The structures of polymer entities isolated from solutions and melts are studied. Under application of the magnetic field to PEG solutions, spherulites of substantially smaller sizes than those formed outside the field appear. The magnetic field increases the degree of crystallinity of PEG, but the degree of crystallinity and size of PE spherulites remain unchanged.     

Biodegradable microspheres with poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide) Enriched surface: Thermo-responsibility,biodegradation and drug release

Microspheres with thermo-responsible surface were fabricated by PCL-b-PEO-b-PNIPAM triblock copolymers. Thermo-responsible morphological changes of PCL-b-PEO-b-PNIPAM microspheres immersed in aqueous solution at temperatures above the LCST (e.g. 37 °C) were observed from porous surface structure to compact surface layer. Enzymatic degradation and in vitro drug release results showed that the thermo-responsible surface layer greatly influenced the degradation of microspheres as well as the drug release behavior from microspheres. With the copolymerization of PNIPAM block into PCL-b-PEO copolymers, the drug release could be well regulated by changing temperatures and microspheres composition, which revealed the great potentials of microspheres with thermo-responsible surface for controlled drug release.     

Poly(<Emphasis Type="Italic">β</Emphasis>-cyclodextrin)-mediated polylactide-cholesterol stereocomplex micelles for controlled drug delivery

A series of host-guest interaction-adjusted polylactide stereocomplex micelles was prepared via the self-assembly of 4-armed poly(ethylene glycol)-block-poly(L-lactide/D-lactide)-cholesterol (4-armed PEG-b-PLLA/PDLA-CHOL) and poly(β-cyclodextrin) (PCD) with the molar ratios of CHOL/β-CD at 1:0.5, 1:1, and 1:2 in an aqueous environment. The hydrodynamic diameters of the micelles ranged from 84.1 nm to 107 nm depending on the molar ratio of CHOL/β-CD. It was shown that the micelle with the largest proportion of PCD possessed excellent abilities in drug release, cell internalization as well as proliferation inhibitory effect toward human A549 lung cancer cells. The results demonstrated that the stereocomplex and host-guest interactions-mediated PLA micelles exhibited great potential in sustained drug delivery.     

Micromechanism of Cu and Fe alloying process on the martensitic phase transformation of NiTi-based alloys: First-principles calculation

Using first-principles pseudo-potential plane wave method, the formation enthalpy ΔH, binding energy ΔE, elastic constants, and electronic structure were calculated and analyzed carefully for NiTiX (X = Cu, Fe) shape memory alloy. The results show that the Cu or Fe element prefers to occupy the Ni site in the NiTi matrix phase respectively. Compared with the NiTi matrix phase, the ΔH, ΔE, c ₄₄ and c′ of NiTi (Cu) are similar to each other. However, the structural stability of the NiTi phase is improved obviously by the Fe alloying process. Simultaneously, the shear modulus c ₄₄ and c′ of NiTi (Fe) are larger than those of the NiTi matrix phase. Furthermore, Milliken population results indicate that Q _Cu–Ti is smaller than Q _Ni–Ti after the Cu alloying process, but Q _Fe–Ti is larger than Q _Ni–Ti. The electron density difference shows that some covalent bonding exists between Fe and Ti elements. Based on the upward analysis, the difference in the phase stability and elastic constants of NiTiX (X = Cu, Fe) is the substantial mechanism for the different M _s of NiTiX (X = Cu, Fe) although Cu or Fe substitutes for the same atom Ni elements in the NiTi matrix phase.     

A Systematic Search for Structures and Stabilities of Asymmetric Clusters (HfInN<Subscript>3</Subscript>)<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> (<Emphasis Type="Italic">n</Emphasis> = 1-6)

In order to find single source precursors (SSP), the structures, relative stabilities, and IR spectra of small asymmetric clusters (HFInN₃) _n (n = 1–6) are systematically investigated by means of the density functional theory at the B3LYP level. The obtained geometries show that the frameworks of clusters (HFInN₃) _n (n = 2–6) prefer to be 2n-membered ring with alternating indium and α-nitrogen atoms. The averaged binding energies reveal that all of asymmetric clusters (HFInN₃) _n (n = 1–6) can continue to gain energy as the cluster size n increasing. The second-order difference of energy (Δ₂E) and the HOMO-LUMO energy gap (E_gap) as a function of the cluster size n both exhibit a pronounced even-odd alternation phenomenon. The influences of cluster size n and temperature T on the thermodynamic properties of clusters are discussed. Judged by enthalpies and Gibbs free energies, the formations of the most stable clusters (HFInN₃) _n (n = 2–6) from the monomer are thermodynamically favorable in the range of 200–800 K.     

Cryochemical synthesis and antibacterial activity of a hybrid composition based on Ag nanoparticles and dioxidine

Hybrid nanocomposites based on an dioxidine antimicrobial substance modified with silver were produced by means of cryochemical synthesis. TEM, UV-absorption spectroscopy, X-ray diffraction, and surface analysis based on low-temperature argon adsorption showed the formation of hybrid nanosystems consisting of drug substance particles with a size of 50–300 nm including internal small Ag nanoparticles with a size of 2–40 nm. The obtained hybrid nanosystems showed higher antibacterial activity against E. coli 52, S. aureus 144, and M. cyaneum 98 than did the original dioxidine.     

Chitosan-Based Surface Molecularly Imprinted Polymer Microspheres for Sustained Release of Sinomenine Hydrochloride in Aqueous Media

The surface molecular imprinting technique has been proposed as a prospective strategy for template molecule recognition and separation by devising the recognition sites on the surface of imprinted materials. The purpose of this study was to establish a novel drug delivery system which was developed by surface molecular imprinting method using β-cyclodextrin (β-CD)-grafted chitosan (CS) (CS-g-β-CD) microspheres as matrix and sinomenine hydrochloride (SM) as the template molecule. By adjusting the amount of functional monomer and cross-linking agent, we got the more excellent adsorption of CS-g-β-CD molecularly imprinted polymers (MIPs-CS-g-β-CD). When the amount of functional monomer was 6 mmol and cross-linking agent was 20 mmol, the maximum binding capacity of MIPs and non-imprinted polymers (NIPs) was 55.9 mg/g and 37.2 mg/g, respectively. The results indicated that the recognition of SM with MIPs was superior to NIPs. The adsorption isotherms of MIPs-CS-g-β-CD indicated that the adsorption behavior fitted better to the Langmuir model, which showed that the adsorption process of polymer was monomolecular layer. In in vitro drug release studies, the accumulative release amount of MIPs-CS-g-β-CD was up to 78% within 24 h. MIPs exhibited an excellent controlled SM release profile without burst release and the mechanism of SM release was shown to conform to non-Fick diffusion. Therefore, MIPs-CS-g-β-CD were successfully applied to extraction of SM and used as the materials for drug delivery system.     

Computational Studies on the Mo-Doped Gold Nanoclusters Au<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>Mo(<Emphasis Type="Italic">n</Emphasis> = 1–10): Structures,Stabilities and Magnetic Properties

The geometric structures, relative stabilities, magnetic properties of Mo-doped gold clusters Au _n Mo(n = 1–10) have been investigated at the PBE1PBE/def2TZVP level of theory. The results show that molybdenum doping has a significant effect on the geometric structures and electronic properties of Au _n Mo(n = 1–10) clusters. For the lowest energy structures of Au _n Mo(n = 1–10), the two dimensional to three dimensional transition occurs at cluster size n ≥ 8, and their relative stabilities exhibit odd–even oscillation with the change of Au atom number. It is found that charge in corresponding Au _n Mo clusters transfers from Mo atom to Au _n host in the size range n = 1–7, whereas the charge in opposition direction in the size range n = 8–10. In addition, the magnetic properties of Au _n Mo clusters are enhanced after doping single Mo atom into the corresponding gold clusters. Our results are valuable for the design of magnetic material.     

Incorporation of biotransformed silver nanoparticles in plant polysaccarides resin and their effect on sustained drug release

The intension of current study was to determine antibacterial and drug releasing capacity of green synthesized silver nanoparticles (AgNps) with Moringa oleifera resin in the presence of Montelukast sodium and Ibuprofen. This plant gum is economic, easily available, biodegradable, safe and potential tablet binder. There was no significant study reported on the incorporation of green synthesized silver nanoparticle with plant resin in drug release. The aqueous extract of Clerodendron phlomoides was used for the bioreduction of silver nanoparticles as well as a capping agent. This green synthesized AgNps was observed in UV at 489 nm due to the SPR (Surface Plasmon Effect) effect, and the presence of protein and polyol compounds was identified by FTIR. The crystalline structure of AgNps was analyzed by XRD, elemental silver composition was measured by EDAX, morphological structure and size was revealed by SEM and TEM analysis. The antibacterial effect of green synthesized AgNps was analyzed by zone of inhibition method. Silver nanoparticles incorporated in M. oleifera plant resin and its functional groups and thermal degradation properties were characterized by FTIR and TGA, respectively. The drug release properties of the AgNps incorporated with plant resin were evaluated for the sustained release and compared with raw plant gum without AgNps consistency.     

Evaluation of network parameters and drug release behavior of gum acacia-crosslinked-carbopol hydrogel wound dressings

Present article discusses the synthesis, characterization, biodegradation, network parameter and drug release of gum acacia-crosslinked-carbopol hydrogel wound dressing. Polymers have been characterized by ¹³C solid state nuclear magnetic resonance spectroscopy, elemental analysis, cryo-scanning electron microscopy, atomic force microscopy, thermogravimetric analysis, differential thermal analysis, differential thermogravimetry, and differential scanning calorimetry studies. Network parameters of hydrogel wound dressings such as polymer volume fraction in the swollen state φ, Flory–Huggins interaction parameter χ, molecular weight of the polymer chain between two neighboring cross links M_c, crosslink density ρ and the corresponding mesh size ξ have also been determined. Different in vitro release kinetic models (zero order, first order, Higuchi square root law, Korsmeyer-Peppas, and Hixson-Crowell cube root models) have been applied on the drug release profile. The release of antibiotic drug moxifloxacin from the drug loaded hydrogel matrix occurred through non-Fickian diffusion mechanism and release profile best fitted in the Korsmeyer-Peppas model. Semi-contact mode atomic force microscopic imaging showed that rough surface with root mean square roughness 82.868 nm of the polymer films.     

Interaction of antitumoral drug erlotinib with biodegradable triblock copolymers: a molecular modeling study

Combination of molecular dynamics simulations and miscibility calculations was used to investigate erlotinib drug delivery systems based on poly-ε-caprolactone–polyethylene glycol–poly-ε-caprolactone (PCL–PEG–PCL) and poly-ε-caprolactone–polyglycolic acid–poly-ε-caprolactone (PCL–PGA–PCL) biodegradable copolymers. The molecular modeling strategy involving visual observation of models, concentration profile analysis, Flory–Huggins χ parameter, cohesive energy density, and mean square displacement calculations reproduced experimental evidence of erlotinib release from PCL–PEG–PCL matrix successfully. Increasing portion of PCL in PCL–PEG–PCL copolymer led to dissolution of erlotinib aggregates recorded in visual and concentration profile analyses. Higher portion of PCL led to higher cohesive energy density and lower mean square displacement values. Success of this strategy in reproduction of experimental data made an opportunity to utilize the same modeling design in prediction of erlotinib release from similar but not yet experimentally tested PCL–PGA–PCL matrix. In this case, agglomeration of erlotinib molecules and stronger cohesive energy density values were observed.     

Distribution or adsorption: the major dilemma in reversed-phase HPLC

A method is suggested for analyzing the dependences obtained for different compositions of mobile eluent system phases, their slopes and intercepts, logk(i, B) = a + b logk (i, A), where a is the intercept for the A and B stationary phases and b is the proportionality factor. An analysis requires parallel investigation of sorbate retention on at least three stationary phases with different lengths of grafted hydrocarbon radicals. The dependence of correlation parameters on the sorbate retention mechanism is discussed. It is shown that the hypothetical dependences coincide with the experimental dependences for surface sorption of resveratrol and volume distribution of triglycerides.     

Free-Radical Co-Oligomerization of <Emphasis Type="Italic">N</Emphasis>-Vinylpyrroles with <Emphasis Type="Italic">N</Emphasis>-Vinylpyrrolidone: A Route to New Bioactive Oligomers

Co-oligomerization of N-vinylpyrroles (N-vinyl-2,3-dimethylpyrrole, N-vinyl-2-phenylpyrrole, N-vinyl-2,3-diphenylpyrrole, N-vinyl-2-(2-thienyl)pyrrole, and N-vinyl-2-[1-(4,5,6,7-tetrahydroindolyl) ethyl]-4,5,6,7-tetrahydroidole) with N-vinylpyrrolidone in the presence of a radical initiator (AIBN) gives co-oligomers with molecular masses of 1600–5200 in up to 87% yield. The products are readily soluble in organic solvents (benzene, 1,4_dioxane, and chloroform), and in the case of high N-vinylpyrrolidone content, also in ethanol and in water. The co-oligomers are non-toxic or have low toxicity (the lethal dose LD₅₀ = 1300–2000) and possess biological activity.     

Formation of Nd<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript>Bi<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>FeO<Subscript>3</Subscript> Nanocrystals under Conditions of Glycine-Nitrate Synthesis

Nd_1–xBi_xFeO₃ nanocrystals with crystallite size 30?60 nm have been prepared under conditions of glycine–nitrate burning. Single-phase Nd_1–xBi_xFeO₃ nanocrystals are formed over the entire studied concentrations range if the glycine–nitrate synthesis is performed in excess of the oxidizer. Under these conditions, a continuous range of the Nd_1–xBi_xFeO₃ solid solutions (0 ≤ х ≤ 0.75) crystallized in the rhombic system (space group Pbnm) are formed without crystallization of the burning intermediates. The Nd_1–xBi_xFeO₃ solid solutions (х = 0.775, 0.8) crystallize in the rhombic system (space group Pbаm).     

Thermal stability of Al-modified silica aerogels through epoxide-assisted sol–gel route followed by ambient pressure drying

Bone infections in human beings are an essentially destructive problem with crucial clinical and economic effects; thus, incorporation of antibiotics such as amoxicillin (AMX) into the scaffold was developed as an effective treatment for bone infections. In this respect, we develop new nanostructured bredigite (Bre; Ca₇MgSi₄O₁₆)–amoxicillin (AMX; α-amino-hydroxybenzyl-penicillin) scaffolds containing different concentrations of amoxicillin (0, 3, 5, and 10%) by using space holder method to assure bactericidal properties. The result depicted that the Bre–AMX scaffolds possess porosity of 80–82% with high compressive strength of 1.2–1.4?MPa and controlled antibiotic release for prevention of infection. Bre–(3–10%)AMX scaffolds were able to destroy Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria, as well as effectively inhibit the growth of bacterial cells; in addition, the antibacterial activity of the AMX-loaded scaffolds augmented with the increase of the AMX concentration. Sustained drug release was detected from Bre–AMX scaffolds accompanied by initial burst release of 20% for 8?h, followed by a sustained release, which is favorable for bone infection treatment. These new Bre–(3–5%)AMX scaffolds possess excellent mechanical properties and antibacterial activity with no cytotoxicity suggested as an appropriate alternative for bone infection treatment.

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Effects of Salts Contained in Lignocellulose-Derived Sugar Streams on Microbial Lipid Production

This study aimed at developing low-cost, robust non-sterile fermentation processes for microbial lipid production from lignocellulose-derived sugars. Three representative oleaginous yeasts, Lipomyces tetrasporus (NRRL Y-11562), Rhodotorula toruloides (NRRL Y-1091), and Yarrowia lipolytica (NRRL YB-437), were tested for lipid production via non-sterile fermentation. Under optimal non-sterile conditions, all the tested strains had good performance on salt tolerance and lipid production. L. tetrasporus (NRRL Y-11562) gave the highest lipid titer of 12.79 g/L along with the depletion of both glucose and xylose, while Y. lipolytica (NRRL YB-437) showed the lowest lipid production and limited capability of xylose utilization. The key factors, including inoculation size, initial pH, and salt, all contributed to successful non-sterile fermentation. This study demonstrated that it is feasible to perform both sterile and non-sterile fermentation for lipid production using salt-containing lignocellulose-derived sugar streams.     

Fast Crystallization and Toughening of Poly(<Emphasis Type="Italic">L</Emphasis>-lactic acid) by Incorporating with Poly(ethylene glycol) as a Middle Block Chain

High molecular weight poly(L-lactic acid)-poly(ethylene glycol)-poly(L-lactic acid) (PLLA–PEG–PLLA; PLGL) triblock copolymers with various lengths of the PLLA blocks were synthesized by ringopening polymerization of L-lactide. The amorphous and crystalline PLLA and PLGL films were prepared by hot pressing with different temperature treatments. PLLA and PEG blocks exhibited good miscibility in the amorphous PLGL samples, while phase separation occurred in the crystalline ones. The flexible PEG blocks not only accelerated the crystallization rate of PLLA but also greatly improve its flexibility. The crystallization time of PLGL copolymers shorten to less than 5 min and copolymers showed much better flexibility than neat PLLA, the maximum fracture strain reached about 600% for amorphous sample. The processing time of PLLA was greatly shortened and the brittleness of material was improved.     

Extraction of Cesium-137 and Americium-241 by Calix[n]arenes from Carbonate-Alkaline Media

Trends of cesium-137 and americium-241 extraction from carbonate–alkaline media with p-tert-butylcalix[n]arenes with macrocycles of different size (n = 4, 6, 8), including monofunctional derivatives with lipophilic substituents for increasing their solubility in organic media, were studied. It was demonstrated that O-n-octyl ethers of p-tert-butylcalix[6]arene appeared to be the most efficient extractants for Cs(I) cations, while it was p-tert-butylthiacalix[4]arene for and americium(III) cations.     

Secondary self-assembly behaviors of PEO-<Emphasis Type="Italic">b</Emphasis>-P<Emphasis Type="Italic">t</Emphasis>BA-<Emphasis Type="Italic">b</Emphasis>-PS triblock terpolymers in solution

A series of PEO₄₅-b-PtBA₅₃-b-PS _x (x = 42, 84, 165) triblock terpolymers were synthesized by the atom transfer radical polymerization and characterized by size exclusion chromatography and ¹H NMR. Their self-assemblies were conducted by a two-step hierarchical self-assembly method and a one-step dialysis method and the self-assembly behaviors were investigated. The morphologies, sizes, and size distributions of micelles produced by the self-assembly were determined by transmission electron microscopy and dynamic light scattering. The secondary self-assembled structure of PEO₄₅-b-PtBA₅₃-b-PS _x obtained by the two-step hierarchical self-assembly could be controlled by tuning the length of PS block, the core forming block. The micelles were uniform with diameters of 20–25 nm and their size distributions, except for that of PEO₄₅-b-PtBA₅₃-b-PS₁₆₅, were narrow with particle size distribution indexes ranging from 0.014 to 0.246. The one-step dialysis of the triblock terpolymers produced vesicular micelles with distinct vesicle walls that exhibited similar thicknesses. The vesicles did not show significant aggregation. The size distribution of PEO₄₅-b-PtBA₅₃-b-PS₄₂ vesicle was the narrowest with a particle size distribution index value of 0.135. The PEO₄₅-b-PtBA₅₃-b-PS₁₆₅ vesicles tended to overlap with each other.