Synthesis and in vitro characterization of a novel PAA–ATP conjugate

The objective of this study was to improve the multifunctional properties of poly(acrylic acid) (PAA) by covalent attachment of 4-aminothiophenol (ATP) to its backbone. The permeation enhancing effect of PAA–ATP together with glutathione was evaluated in Ussing-type chambers using fluorescein isothiocyanate dextran as model compound. The mucoadhesive properties were evaluated in vitro on freshly excised porcine intestinal mucosa through the rotating cylinder method. The resulting conjugates PAA–ATP1 and PAA–ATP2 displayed 168 ± 35 and 426 ± 55 μmol immobilized free thiol groups per gram polymer, respectively. In addition, 279 ± 28 and 139 ± 22 μmol disulfide bonds per gram polymer, respectively, were identified on PAA–ATP1 and PAA–ATP2. Within disintegration studies in aqueous buffer solution, the modified polymers showed improved cohesive properties. Because of the immobilization of ATP, the swelling of PAA–ATP1 and PAA–ATP2 improved 12.0- and 17.8-fold, respectively. The adhesion times of the conjugates PAA–ATP1 and PAA–ATP2 were more than 20- and 30-fold increased in comparison to unmodified PAA. Furthermore, conjugates PAA–ATP1 and PAA–ATP2 exhibited a 1.86- and 2.07-fold higher permeation enhancing effect, respectively, over unmodified PAA. According to these results, PAA–ATP conjugates represent a very promising novel type of thiomer for the development of various mucoadhesive drug delivery systems.     

In vitro and in vivo characterization of fast dissolving tablets containing gliquidone–pluronic solid dispersion

Abstract

The main objective of this study is to increase the dissolution rate of gliquidone using its solid dispersions with pluronic F-68 by solvent evaporation method. The solid dispersion of the drug with pluronic at ratio 1:3 showed the highest dissolution efficiency (50.7%) after 10?min, so it was incorporated in fast dissolving tablets. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were used to study the interaction between gliquidone and pluronic in the solid state. The FTIR spectroscopic studies revealed no chemical interaction between the drug and pluronic, while the DSC results indicated the amorphous state of gliquidone in the solid dispersion. A 3² full factorial design was used to study the effect of varying concentrations of croscarmellose and sodium starch glycolate as superdisintegrants on the disintegration time and the percentage released after 10?min. The optimized formula showed a disintegration time of 39.1?±?1.2?s and 85.43%?±?5.16% released after 10?min and was selected for the in-vivo studies in rabbits. The selected formula showed significant enhancement of gliquidone bioavailability, about 1.8 times compared with the commercial Glurenor tablets.     

Biological performance of wood–plastic composites containing zinc borate: Laboratory and 3-year field test results

Six different formulations of wood–plastic composites (WPC) fabricated from wood and polypropylene (PP) were tested in the laboratory against decay and termites and in a protected above-ground field test in southern Japan. Variables examined included comparisons of untreated and zinc borate (ZnB) incorporated formulations, wood content ratio, wood particle size and increased surface area via surface grooves (channels) to promote moisture infusion. A standard method originally designed to test durability of solid wood was modified for testing WPC. Wood decay fungi and Formosan subterranean termite activity in laboratory and field tests resulted in different mass losses, post-decay moisture contents and field test ratings depending on their wood and ZnB content. The results show that as wood content increased, mass losses also increased. Addition of ZnB at 1% (w/w) retention level significantly decreased mass losses of wood–plastic composite when exposed to laboratory decay and termite tests. The effects of surface grooves and wood particle size were less important, compared to wood particle content. All WPC tested were highly resistant to fungal decay under protected above-ground field conditions during 36 months. Termite attack, on the other hand, started at earlier stage reducing mean ratings 1 year after the installation.     

Fabrication and properties of novel composites in the system Al–Zr–C

Composite bodies in the system Al–Zr–C, with about 95% relative density, were obtained by heating the compact body of powder mixture consisting of Al and ZrC (5 : 1 mol %) in Ar at 1100–1500°C for various lengths of time. Components of the material heated at more than 1200°C were Al, Al3Zr, ZrC and AlZrC2. The Al3Zr exhibited plate-like aggregation, and its size increased with increasing temperature. In the material heated at 1500°C for 1 h, the largest plate-like Al3Zr aggregation was 2000 m long and 133 m thick. Then the AlZrC2 was present as well-proportioned hexagonal platelet particles with a 8–9 m diameter and a 1–2 m thickness in the interior of the plate-like Al3Zr aggregation and Al matrix phase. The average three-point bending strength of the bodies was 140–190 MPa, and the maximum strength was 203 MPa in the body heated at 1300°C for 1 h. The body heated at 1500°C for 1 h showed high oxidation resistivity to air up to 1000°C.     

Innovation of novel ‘Tab in Tab’ system for release modulation of milnacipran HCl: optimization,formulation and in vitro investigations

The study was aimed toward development of modified release oral drug delivery system for highly water soluble drug, Milnacipran HCl (MH). Novel Tablet in Tablet system (TITs) comprising immediate and extended release dose of MH in different parts was fabricated. The outer shell was composed of admixture of MH, lactose and novel herbal disintegrant obtained from seeds of Lepidium sativum. In the inner core, MH was matrixed with blend of hydrophilic (Benecel^®) and hydrophobic (Compritol^®) polymers. 3² full factorial design and an artificial neuron network (ANN) were employed for correlating effect of independent variables on dependent variables. The TITs were characterized for pharmacopoeial specifications, in vitro drug release, SEM, drug release kinetics and FTIR study. The release pattern of MH from batch A10 containing 25.17% w/w Benecel^® and 8.21% w/w of Compritol^® exhibited drug release pattern close proximal to the ideal theoretical profile (t_50% = 5.92?h, t_75% = 11.9?h, t_90% = 18.11 h). The phenomenon of drug release was further explained by concept of percolation and the role of Benecel^® and Compritol^® in drug release retardation was studied. The normalized error obtained from ANN was less, compared with the multiple regression analysis, and exhibits the higher accuracy in prediction. The results of short-term stability study revealed stable chataracteristics of TITs. SEM study of TITs at different dissolution time points confirmed both diffusion and erosion mechanisms to be operative during drug release from the batch A10. Novel TITs can be a succesful once a day delivery system for highly water soluble drugs.     

Properties and in vitro characterization of polyhydroxybutyrate–chitosan scaffolds prepared by modified precipitation method

Porous polyhydroxybutyrate (PHB)–chitosan biopolymer scaffolds were prepared by co-precipitation from biopolymer solutions with propylene carbonate and acetic acid as solvents. A change of the fibrous character of chitosan precipitates to globular shaped forms with a polyhydroxybutyrate addition was found in suspensions. Scaffolds differ by porosity and morphology of polymers in microstructures, while chitosan represented more compact plate-like fibers and PHB characterized mainly fine fibrous globular agglomerates. Two structurally dissimilar phase regions were verified in blended scaffolds. A rise in the number of smaller pores, and fine structured polymer forms with PHB content were observed in the scaffolds. A significant reduction in the average molecular weight of biopolymers was found in pure chitosan scaffold, this after precipitation of the chitosan in the presence of propylene carbonate and in blends after mutual biopolymer mixing. Interactions between shortened chitosan chains, PHB and chitosan biopolymers in the blends were observed. An excellent fibroblast proliferation was found in scaffolds prepared from biopolymer blends.     

Supermacroprous chitosan–agarose–gelatin cryogels: in vitro characterization and in vivo assessment for cartilage tissue engineering

The study focuses on the synthesis of a novel polymeric scaffold having good porosity and mechanical characteristics synthesized by using natural polymers and their optimization for application in cartilage tissue engineering. The scaffolds were synthesized via cryogelation technology using an optimized ratio of the polymer solutions (chitosan, agarose and gelatin) and cross-linker followed by the incubation at sub-zero temperature (−12°C). Microstructure examination of the chitosan–agarose–gelatine (CAG) cryogels was done using scanning electron microscopy (SEM) and fluorescent microscopy. Mechanical analysis, such as the unconfined compression test, demonstrated that cryogels with varying chitosan concentrations, i.e. 0.5–1% have a high compression modulus. In addition, fatigue tests revealed that scaffolds are suitable for bioreactor studies where gels are subjected to continuous cyclic strain. In order to confirm the stability, cryogels were subjected to high frequency (5 Hz) with 30 per cent compression of their original length up to 1 × 10⁵ cycles, gels did not show any significant changes in their mass and dimensions during the experiment. These cryogels have exhibited degradation capacity under aseptic conditions. CAG cryogels showed good cell adhesion of primary goat chondrocytes examined by SEM. Cytotoxicity of the material was checked by MTT assay and results confirmed the biocompatibility of the material. In vivo biocompatibility of the scaffolds was checked by the implantation of the scaffolds in laboratory animals. These results suggest the potential of CAG cryogels as a good three-dimensional scaffold for cartilage tissue engineering.     

Synthesis and characterization of MeO–PEG–PLGA–PEG–OMe copolymers as drug carriers and their degradation behavior in vitro

The objective of this study was to characterize the methylpoly (ethylene glycol)-poly (lacticacid-co-glycolicacid)-poly (ethylene-glycol) (MeO-PEG-PLGA-PEG-OMe, abbreviation as PELGE) copolymers as intravenous injection drug delivery carriers and their degradation behavior in vitro. A series of MeO-PEG-PLGA-PEG-OMe copolymers with various molar ratios of lactic to glycolic acid and various molecular weights and different MeO-PEG contents were synthesized by ring-opening polymerization in the presence of MeO-PEG with molar masses of 2000 and 5000, using stannous octoate as the catalyst. The hydrophilicity of PELGE copolymers, evaluated by contact angle measurements, was found to increase with an increase in their MeO-PEG contents. Methylpoly (ethylene glycol)-poly (lacticacid-co-glycolicacid) (MeO-PEG-PLGA, abbreviation as PELGA) nanoparticles and PELGE nanoparticles were prepared using the emulsion-solvent evaporation technique (o/w) with Pluronic F68 (Poloxamer 188 NF) as emulsifier in the external aqueous phase. The degradation behavior of the nanoparticles was evaluated by the lactate generation with time upon their in vitro incubation in PBS (pH 7.4). The rate of in vitro degradation of the PELGE or PELGA nanoparticles depended on their composition, increasing with an increase in the proportion of MeO-PEG or LA in the copolymer chains. The degradation rate was slower at higher lactide: glycolide ratio. The lower the molecular weight of PELGE; the higher the degradation rate of the nanoparticles.     

Formulation,characterization and in vitro–in vivo evaluation of flurbiprofen-loaded nanostructured lipid carriers for transdermal delivery

Flurbiprofen is used in the treatment of arthritis. However, its multiple dosing due to short elimination half life is a concern for such treatment. This work aims to develop nanostructured lipid carriers (NLCs) of flurbiprofen and evaluate their potential for transdermal delivery. The NLCs were prepared by the optimized o/w emulsification-homogenization-sonication technique using coconut oil (liquid lipid). The NLCs were found to be spherical with uniform size (214 nm). The entrapment efficiency and zeta potential were 92.58% and ?30.70 mV, respectively. Differential scanning calorimetry (DSC) showed the amorphous state of flurbiprofen encapsulated in NLCs. The percentage cumulative drug release through the excised rat skin from NLCs was biphasic and significantly prolonged compared with the commercial gel. DSC of the treated skin indicated that the NLCs penetrate into follicles of the skin and accumulate in the dermis. The bioavailability of flurbiprofen from NLCs was more than 1.7-fold that of the commercial gel. The NLCs showed a quick onset and sustained anti-inflammatory effect over period of 24 h for carrageenan-induced rat paw edema than the commercial gel. The stability data revealed that the NLCs were more stable when stored at 5°C. In conclusion, prepared NLCs have potential for skin targeting and sustained drug release.     

Degradative and mechanical properties of a novel resorbable plating system during a 3-year follow-up in vivo and in vitro

We tested the tissue reactions and mechanical strength of a novel biodegradable craniomaxillofacial plating system, Inion CPS™, in the course of degradation. Plates and screws composed of l-lactide, d-lactide and trimethylene carbonate were implanted to the mandible and dorsal subcutis of 12 sheep. The animals were sacrificed at 6–156 weeks. Histological evaluation was done using paraffin and methylmetacrylate techniques. Degradative and mechanical properties during the follow-up were measured both of in vivo and in vitro implants. In light microscopy, the in vivo implant material began to fragment at 52 weeks and could not be detected at 104 weeks. No significant foreign body reactions were seen in the mandibles. The dorsal subcutis disclosed mild reactions, which were, however, not of clinical significance. The implants in vitro maintained their entire mass for 26 weeks and lost 63–80% of the mass by week 104. The inherent viscosity of the implants in vitro and in vivo diminished uniformly. The screws retained their shear strength for 12–16 weeks. The plates maintained their tensile strength for at least 6 weeks. The maximum capacity of the plates in 3-point bending tests diminished gradually by 87% in 26 weeks. In conclusion, the plates and screws examined maintain adequate strength for the healing period of a bone fracture or osteotomy, producing no harmful foreign body reactions. Dr Nieminen is a consultant for Inion Ltd., while the other co-authors do not have any conflicts of interest. Inion Ltd. has financed the costs related to the study sheep, including their housing.     

Hydrogel–elastomer composite biomaterials: 1. Preparation of interpenetrating polymer networks and in vitro characterization of swelling stability and mechanical properties

We prepared interpenetrating polymer networks (IPNs) composed of a gelatin hydrogel and a HydroThane^TM elastomer to combine the advantages of both polymers into one biomaterial. Fourier transform Infrared (FTIR) spectroscopy and Differential Scanning Calorimetry (DSC) confirmed the co-existence of the two polymers in the IPNs. Optical light microscopy confirmed hydrogel domains were interspaced into an elastomer network. Hydration and stability studies in aqueous solution showed that, although the IPN biomaterials exhibited stable swelling for more than 30 days, approximately 10% and 50% loss of the hydrogel component were confirmed at room temperature and 37 °C, respectively, using gel permeation chromatography (GPC). The swelling study in the serum-containing medium indicated the biomaterials maintained their swelling stability for different periods, depending on the extent of gelatin methacrylation, photoinitiator concentration and incubation temperature. Lastly, the biomaterials exhibited higher failure stress and lower failure strain in a dry state than in a swollen state, and showed limited changes in both stress and strain at room temperature and at 37 °C, in contrast with a decrease at 50 °C. No significant effects of gelatin methacrylation on mechanical properties were noticed. The preparation and characterization methods were well established and formed the basis of further developing the biomaterials.     

Synthesis,characterization and evaluation of bioactivity and antibacterial activity of quinary glass system (SiO2–CaO–P2O5–MgO–ZnO): In vitro study

Bioactive glasses in the systems SiO₂–CaO–P₂O₅–MgO (BGZn0) and SiO₂–CaO–P₂O₅–MgO–ZnO (BGZn5), were prepared by sol–gel method and then characterized. Surface reactivity was studied in simulated body fluid (SBF) to determine the effect of zinc (Zn) addition as a trace element. The effect of Zn addition to the glass matrix on the formation of apatite layer on the glass surface was investigated through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT–IR) and scanning electron microscopy (SEM). Also, inductively coupled plasma–optical emission spectroscopy (ICP–sOES) was used to determine the concentrations of released ions in SBF solution after different time intervals in SBF solution. The antibacterial activity of Zn containing glass against Pseudomonas aeruginosa was measured by the halo zone test. The presence of Zn in glass composition improved chemical durability, slowed down the formation rate of Ca–P layer and decreased the size of crystalline apatite particles. Zn containing glass exhibited an excellent antibacterial activity against P. aeruginosa which could demonstrate its ability to treat bone infection.     

Synthesis,characterization and in vitro bioactivity of sol-gel-derived SiO2–CaO–P2O5–MgO bioglass

In this study, the synthesis of SiO₂–CaO–P₂O₅–MgO bioactive glass was performed by the sol-gel method. Sol-gel-derived bioglass material was produced both in powder and in discs form by uniaxial pressing, followed by sintering at 700 °C. The obtained material was evaluated by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermal gravimetric analysis (TGA) and differential scanning caloremetry (DSC) analyses. The biocompatibility evaluation of the formed glass was assessed through in vitro cell culture [alkaline phosphatase (AP) activity of osteoblasts] experiments and immersion studies in simulated body fluid (SBF) for different time intervals while monitoring the pH changes and the concentration of calcium, phosphorus and magnesium in the SBF medium. The SEM, XRD and FTIR studies were conducted before and after soaking of the material in SBF. At first, an amorphous calcium phosphate was formed; after 7 days this surface consisted of deposited crystalline apatite. The present investigation also revealed that the sol-gel derived quaternary bioglass system has the ability to support the growth of human fetal osteoblastic cells (hFOB 1.19). Finally, this material proved to be non-toxic and compatible for the proposed work in segmental defects in the goat model in vivo.     

Photo-immobilized heparin micropatterns on Ti–O surface: preparation,characterization, and evaluation in vitro

In order to harmonize the functions of both anticoagulation and accelerating endothelialization simultaneously, the micropatterns were fabricated by photoimmobilizing heparin, functionalized with a photoreactive moiety, on 3-aminopropylphosphonic acid modified titanium oxide (Ti–O) substrates. The amount of heparin immobilized on the surfaces was determined using the toluidine blue assay. And the surface morphology of the patterns was examined using scanning electron microscopy and surface profiler. The platelet adhesion and endothelial cell behavior in terms of adhesion, proliferation, and orientation were investigated in vitro. It is clear that the heparin patterns can reduce the platelet adhesion, and promote endothelial cells spreading and proliferation compared to nonpatterned heparin sample. Furthermore, the microstripes with appropriate size can induce the cells to elongate and arrange along the stripe direction. This may suggest a new modification method for blood-contacting device.     

Hyaluronan-based heparin-incorporated hydrogels for generation of axially vascularized bioartificial bone tissues: in vitro and in vivo evaluation in a PLDLLA–TCP–PCL-composite system

Smart matrices are required in bone tissue-engineered grafts that provide an optimal environment for cells and retain osteo-inductive factors for sustained biological activity. We hypothesized that a slow-degrading heparin-incorporated hyaluronan (HA) hydrogel can preserve BMP-2; while an arterio–venous (A–V) loop can support axial vascularization to provide nutrition for a bio-artificial bone graft. HA was evaluated for osteoblast growth and BMP-2 release. Porous PLDLLA–TCP–PCL scaffolds were produced by rapid prototyping technology and applied in vivo along with HA-hydrogel, loaded with either primary osteoblasts or BMP-2. A microsurgically created A–V loop was placed around the scaffold, encased in an isolation chamber in Lewis rats. HA-hydrogel supported growth of osteoblasts over 8 weeks and allowed sustained release of BMP-2 over 35 days. The A–V loop provided an angiogenic stimulus with the formation of vascularized tissue in the scaffolds. Bone-specific genes were detected by real time RT-PCR after 8 weeks. However, no significant amount of bone was observed histologically. The heterotopic isolation chamber in combination with absent biomechanical stimulation might explain the insufficient bone formation despite adequate expression of bone-related genes. Optimization of the interplay of osteogenic cells and osteo-inductive factors might eventually generate sufficient amounts of axially vascularized bone grafts for reconstructive surgery.     

Sol–gel synthesis, characterization, and in vitro compatibility of iron nanoparticle-encapsulating silica microspheres for hyperthermia in cancer therapy

We prepared iron nanoparticle-encapsulating silica (FeSi) microspheres and tested their suitability as thermal seeds for hyperthermia in cancer therapy. These microspheres were prepared by introducing a ferric ion (Fe³⁺) into microspheres of a SiO₂ gel matrix derived from the hydrolysis of tetramethoxysilane in a water-in-oil emulsion that was then heat-treated at 850?°C in an argon atmosphere. The particles obtained were 5–30?μm in size and had a saturation magnetization up to 21?emu?g^?1 and a coercive force of 86–133?Oe. Heat generation in an alternating current magnetic field of 300?Oe at 100?kHz was estimated to be 7.7–28.9?W?g^?1. The in vitro cell biocompatibility of the microspheres was assessed by culturing rat fibroblast Rat-1 cells in medium supplemented with microspheres containing 6.7?% of iron nanoparticles. At microsphere concentrations of <7.5?g?L^?1 proliferation of Rat-1 cells was not significantly inhibited.     

Sustained-release of Cyclosporin A pellets: preparation,in vitro release,pharmacokinetic studies and in vitro–in vivo correlation in beagle dogs

The aim of this study was to develop Cyclosporin A (CsA) sustained-release pellets which could maintain CsA blood concentration within the therapeutic window throughout dosing interval and to investigate the in vitro–in vivo correlation (IVIVC) in beagle dogs. The CsA sustained-release pellets (CsA pellets) were prepared by a double coating method and characterized in vitro as well as in vivo. Consequently, the CsA pellets obtained were spherical in shape, with a desirable drug loading (7.18?±?0.17?g/100?g), good stability and showed a sustained-release effect. The C_max, T_max and AUC_0–24 of CsA pellets from the in vivo pharmacokinetics evaluation was 268.22?±?15.99?ng/ml, 6?±?0?h and 3205.00?±?149.55?ng·h/ml, respectively. Compared with Neoral®, CsA pellets significantly prolonged the duration of action, reduced the peak blood concentration and could maintain a relatively high concentration level till 24?h. The relative bioavailability of CsA pellets was 125.68?±?5.37% that of Neoral®. Moreover, there was a good correlation between the in vitro dissolution and in vivo absorption of the pellets. In conclusion, CsA pellets which could ensure a constant systemic blood concentration within the therapeutic window for 24?h were prepared successfully. Meanwhile, this formulation possessed a good IVIVC.     

Development and evaluation of a novel drug delivery: Soluplus®/TPGS mixed micelles loaded with piperine in vitro and in vivo

Background: Although piperine can inhibit cells of tumors, the poor water solubility restricted its clinical application. This paper aimed to develop mixed micelles based on Soluplus^® and D-α-tocopherol polyethylene glycol succinate (TPGS) to improve the aqueous solubility and anti-cancer effect.

Methods: Piperine-loaded mixed micelles were prepared using a thin-film hydration method, and their physicochemical properties were characterized. The cellular uptake of the micelles was confirmed by confocal laser scanning microscopy in A549 lung cancer cells and HepG₂ liver cancer cells. In addition, cytotoxicity of the piperine mixed micelles was studied in A549 lung cancer cells and HepG₂ liver cancer cells. Free piperine or piperine-loaded Soluplus^®/TPGS mixed micelles were administered at an equivalent dose of piperine at 3.2?mg/kg via a single intravenous injection in the tail vain for the pharmacokinetic study in vivo.

Results: The diameter of piperine-loaded Soluplus^®/TPGS (4:1) mixed micelles was about 61.9?nm and the zeta potential –1.16?±?1.06?mV with 90.9% of drug encapsulation efficiency and 4.67% of drug-loading efficiency. Differential scanning calorimetry (DSC) studies confirmed that piperine is encapsulated by the Soluplus^®/TPGS. The release results in vitro showed that the piperine-loaded Soluplus^®/TPGS mixed micelles presented sustained release behavior compared to the free piperine. The mixed micelles exhibited better antitumor efficacy compared to free piperine and physical mixture against in A549 and HepG₂ cells by MTT assay. The pharmacokinetic study revealed that the AUC of piperine-loaded mixed micelles was 2.56 times higher than that of piperine and the MRT for piperine-loaded mixed micelles was 1.2-fold higher than piperine (p?Conclusion: The results of the study suggested that the piperine-loaded mixed micelles developed might be a potential nano-drug delivery system for cancer chemotherapy. These results demonstrated that piperine-loaded Soluplus^®/TPGS mixed micelles are an effective strategy to deliver piperine for cancer therapy.