Matrix Erosion Research Articles

Fabrication of soy protein isolate/κ-carrageenan hydrogels for release control of hydrophilic compounds: Flax lignans

A suitable carrier for flax lignans using Soybean protein isolated (SPI) - κ-carrageenan (KC) hydrogels was developed. The effects of KC concentration on the stability of hydrogels were investigated, as well as water holding capacity (WHC), syneresis and morphological changes. A solid-like gel network and viscoelasticity of composite hydrogels were confirmed by rheological behavior test. Scanning electron microscopy (SEM) displayed a dense and uniform structure for hydrogels with the optimum KC concentration (0.6 %). Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) curves suggested lignan might interact with SPI and KC by hydrogen bonding or hydrophobic effects. The release of flax lignans in hydrogels was followed with Fick diffusion in simulated gastric fluids (SGF) and non-Fickian diffusion in simulated intestinal fluids (SIF), respectively. The cumulative release rate of flax lignan in complex gels (46.00 %) was lower than that of pure SPI hydrogels (77.43 %) at the end of digestion. The results indicated that KC protected the protein by hindering the accession of digestive enzymes into the hydrogels, thus resulting in a reduction of gel matrix erosion and lignan release during digestion. These findings shield a light on SPI-KC hydrogels as carriers for water-soluble bioactive compounds in food and pharmaceutical industries.

Preparation, optimization and in vivo study of gastric floating tablets of constunolide and dehydrocostus lactone with ideal therapeutic effect on gastric diseases

Costunolide (COS) and dehydrocostus lactone (DEH), as natural phytochemical components, mainly originated from Aucklandiae radix (AR) and Vladimiriae radix (VR) used in the treatment of gastric diseases in traditional Chinese medicine. The α-methylene-γ-butyrolactone ring structure is the same active part of COS and DEH, and shows good curative effects, such as breast cancer, leukemia and gastric related diseases. Furthermore, the previous research of the lab team found that the combination of COS and DEH promoted the repair of gastric ulcer and effectively alleviated intestinal metaplasia of gastric mucosa. Nevertheless, the rapid gastric emptying process and inefficient gastrointestinal absorption resulted in low oral bioavailability of COS and DEH. Based on floating and swelling technology, this study developed a gastric floating drug delivery system for prolonging gastric residence time to delay the drug release in the stomach and enhance the bioavailability of COS and DEH. The gastric floating tablets of COS and DEH were prepared by the direct powder compression method, and the optimized formulation contained 30% HPMC K15 M and 10% NaHCO3. The results of response variable showed that the floating lag time was 13.50 ± 1.87 s, total floating time was 11.83 ± 0.41 h, 2 h and 12 h cumulative drug release was 29.87 ± 2.22%, 70.89 ± 4.27%, respectively. Additionally, the physicochemical properties of the floating tablets were characterized by friability, hardness, weight variation, Fourier transform infrared spectrum (FT-IR), differential scanning calorimeter (DSC) and X-ray diffraction (X-RD). The study on release kinetics showed that the drug release mechanism of gastric floating tablets of COS and DEH was both diffusion and matrix erosion. Moreover, scanning electron microscope (SEM), swelling and erosion indexes studies further explained the release mechanism. Furthermore, in vivo X-ray imaging of male New Zealand rabbits proved the gastric retention effect of the gastric floating tablets in the stomach (10 ± 3.46 h). The results of these experiments demonstrated that the gastric floating tablets of COS and DEH had the potential for a good gastric residence time and sustained release effect.

Anthocyanins Formulated with Carboxymethyl Starch for Gastric and Intestinal Delivery.

Anthocyanins obtained from jambolan have been used as active agents in different carboxymethyl starch-based tablet formulations and their release profiles evaluated in simulated gastric fluids (SGF) and simulated intestinal (SIF) fluids. Structural analysis highlighted a strong interaction between anthocyanins and carboxymethyl starch, evidenced by scanning electron microscopy and infrared analysis. Tablet dissolution behavior varied according to the pH of the media, being controlled by the swelling and/or erosion of the polymeric matrix. Various formulations for immediate, fast, and sustained release of anthocyanins for 30 min, 2 h and 12 h of dissolution have been developed. It was found that monolithic carboxymethyl starch tablets loaded with powdered jambolan extract efficiently afforded the complete delivery (100% of anthocyanins) to different sites of the simulated gastrointestinal tract and ensured the stability of these pigments, which maintained their antioxidant activity.

Formation Mechanism of “Large-Area Sweating” Water Seepage from Deep Mine Sandstone Pores

The groundwater in nonkarst areas can be divided into two categories: pore water and fracture water. Unlike fracture seepage, sandstone pore seepage in deep mines manifests as a large area of “sweating,” rather than an area of local “spray,” and is difficult to plug via conventional grouting methods. This study focused on pore seepage in deep mine sandstone to improve the grouting effect. Taking the deep mine sandstone in the southwest Shandong coal field, where “large-area sweating” seepage occurs, as the study object, this study examined the pore structure, petrological characteristics, physical properties, and grain sizes of the sandstone by analyzing experimental data from thin sections and scanning electron microscopy samples. The formation mechanism of the “large-area sweating” seepage was then analyzed. The range of permeability in which “large-area sweating” seepage may occur in the sandstone was discussed. The results indicate that the process of “large-area sweating” seepage in deep mine sandstone can be divided into a matrix softening stage, a matrix erosion stage, and a “large-area sweating” water seepage formation stage. According to the case analysis on the “large-area sweating” seepage in the Tangkou coal mine of the Southwest Shandong coalfield, the lower limit of permeability of the “large-area sweating” sandstone is approximately 0.25 mD. Thus, this type of seepage can occur in deep mine sandstone with a permeability of greater than 0.25 mD and affect typical mining production. The results of this study provide information about the formation mechanism of “large-area sweating” water seepage from sandstone pores and can theoretically inform the development of a new permeation grouting technique.

In Situ Swelling Formulation of Glycerol-Monooleate-Derived Lyotropic Liquid Crystals Proposed for Local Vaginal Application.

Hydrogels have been extensively investigated to identify innovative formulations that can fulfill all the necessary purposes to improve local vaginal therapy through the mucosa. Herein, we propose in situ-forming lyotropic liquid crystals (LLCs) derived from a cheap and GRAS (generally recognized as safe) ingredient as an intravaginal delivery system. The system consists of a precursor solution loaded with sertaconazole nitrate as a model drug, which is able to easily swell in a stable three-dimensional structure by absorbing simulated vaginal fluid. Under polarized light microscopy the precursor solution and the formed phase of LLCs showed the typical textures belonging to anisotropic and an isotropic mesophases, respectively. A deep rheological investigation by Kinexus® Pro proved the stability and strength of the cubic phase, as well as its potential in mucoadhesion. In vitro degradation studies showed a slow matrix erosion, consistent with data obtained from lipophilic drug release studies in simulated vaginal fluid. Therefore, the suggested cubic phase based on lyotropic liquid crystals could represent a valid proposal as a vaginal drug delivery system due to its characteristics of resistance, adhesion and the possibility of providing a slow and controlled release of drugs directly at the administration site.

Sustained Release Matrix Technology for Cefixime- A Review

Sustained release drug delivery system is designed to sustain the release of the drug dosage forms at a predetermined rate. Sustained release formulation maintains uniform drug level in therapeutic window, improved efficacy of drug by localization at the site of action with better patient compliance, reducing the dose required, providing uniform drug delivery. The sustained release formulations minimize the frequency of drug administration and do not interfere with the therapeutic action of the drug. The use of sustained release matrix technology for antibiotics is effective in preventing the resistant of antibiotics in body on irrational use. Drug release through matrix SRDDS is determined by Polymer swelling, Water penetration, Drug dissolution, diffusion, Matrix erosion. The present article contains brief review on various formulation approaches for Sustained release drug delivery system, advantages, selection criteria for matrix SRDDS and use of cefixime trihydrate in formulating matrix SRDDS.

Curcumin loaded hydrogel with anti-inflammatory activity to promote cartilage regeneration in immunocompetent animals

Stable cartilage regeneration in immunocompetent animals remains a huge challenge, mainly ascribing to the in vivo implantation of tissue-engineered cartilage inevitably arousing inflammatory reactions, resulting in cartilage-specific extracellular matrix erosion, chondrogenic niche destruction, and chondrocyte deterioration. Herein, we developed an anti-inflammatory platform, namely, Cur/GelMA hydrogel, by loading a potent anti-inflammatory drug of curcumin (Cur) into gelatin methacryloyl (GelMA) hydrogel. The Cur/GelMA hydrogel exhibited satisfactory Cur release kinetics in vitro and exerted favorable anti-inflammatory effects when cocultured with lipopolysaccharide-induced RAW264.7 macrophages in vitro. Furthermore, the Cur/GelMA hydrogel showed gratifying biocompatibility and supported cartilage regeneration in vitro when colonized with rabbit- and goat-derived chondrocytes. In addition, the in vitro engineered cartilages in the Cur/GelMA hydrogel were able to maintain a cartilaginous phenotype and achieved stable cartilage regeneration when subcutaneously implanted in autologous rabbits and goats for 2 and 4 weeks compared to the GelMA hydrogel. Furthermore, our data revealed that the in vivo-generated cartilage in the Cur/GelMA group apparently alleviated the inflammatory reaction compared to its GelMA counterpart, suggesting that the locally released Cur endowed the Cur/GelMA hydrogel with potent anti-inflammatory capacity. This study provides a reliable anti-inflammatory platform for stable cartilage regeneration in immunocompetent animals, significantly advancing the clinical application of tissue-engineered cartilage.

Stereomicroscope with Imaging Analysis: A Versatile Tool for Wetting, Gel Formation and Erosion Rate Determinations of Eutectic Effervescent Tablet.

Wettability, gel formation and erosion behaviors could influence the drug release pattern of solid dosage forms. Typically, these parameters are evaluated using a variety of techniques. Nonetheless, there has been no previous research on versatile tool development for evaluating several tablet characteristics with a single tool. The aim of this study was to develop the versatile tool for measuring various physical properties of eutectic effervescent tablets and also investigate the relationship between these parameters with parameters from drug dissolution. Ibuprofen (IBU)-poloxamer 407 (P407) eutectic effervescent tablets were fabricated with a direct compression method. Their wetting properties, gel formation and erosion behaviors were investigated using a stereomicroscope with imaging analysis in terms of the liquid penetration distance, gel thickness and erosion boundary diameter, respectively. In addition, the dissolution rate (k) and disintegration time of eutectic effervescent tablets in 0.1 N HCl buffer pH 1.2 were also determined. Incorporation of P407 into the IBU tablet improved the tablet wetting properties with increasing liquid penetration distance under stereoscope. CO2 liberation from effervescent agents promoted tablet surface roughness from matrix erosion. The relationship between observed physical properties and disintegration and dissolution parameters suggested that the combination of erosion by effervescent agents and gel formation by P407 had a potential influence on dissolution enhancement of the formulation. Therefore, a developed stereomicroscope with an imaging analysis technique was exhibited as an alternative versatile tool for determining the wetting properties, gel formation and erosion behaviors of pharmaceutical solid dosage forms.

Preparation, characterization and evaluation of capsaicin-loaded indica rice starch nanoparticles

Capsaicin (CAP) is an alkaloid with multiple physiological effects, but its application is difficult. In this research, indica rice starch nanoparticles (IRSNPs) based nanocarrier was used to load CAP to obtain capsaicin-loaded indica rice starch nanoparticles (CAP-IRSNPs). The microstructure, characteristics and in vitro release behaviors of CAP-IRSNPs were analyzed. CAP-IRSNPs presented average particle sizes of 617.84 ± 6.38 nm, encapsulation efficiency of 70.05 ± 1.78% and loading capacity of 13.41 ± 0.18%. Fourier-transform infrared spectroscopy confirmed that CAP-IRSNPs might be formed by hydrogen-bonding action. Differential scanning calorimetry and X-ray diffraction showed that IRSNPs influenced the crystallization and melting temperatures of CAP. In in vitro release study, CAP-IRSNPs exhibited a sustained release. The CAP concentration, CAP diffusion from matrix and matrix erosion might be the potentially possible mechanisms for capsaicin release from CAP-IRSNPs. These new results concluded that IRSNPs may be a promising nanocarrier for CAP or other hydrophobic bioactive ingredients.

Application of focused ion beam-field emission scanning electron microscopy-X-ray microanalysis in the study of the surface alterations of archaeological tin-glazed ceramics

The historical evolution of tin-glazed ceramics is a subject that has attracted the attention of many scientists and, consequently, abundant archaeometrical studies can be found in the specialized literature. Nevertheless, a lesser number of studies aimed at the characterization of the alterations undergone by archaeological glazes has been reported. This work describes some unusual alteration processes found in tin-glazes depending on the environmental conditions surrounding the piece during centuries. For this purpose, focused ion beam-field emission scanning electron microscopy-X-ray microanalysis (FIB-FESEM-EDX), an advanced instrumental technique for surface analysis at the nanoscale, has been used for the first time, complementarily to optical microscopy (OM), FESEM-EDX and Fourier transform Infrared spectroscopy (FTIR). In the buried glaze the nanostructure of the outer lamellar corrosion layer due to humidity-dryness cycles is described. Unusual and selective erosion of the glaze matrix due to the silicification metabolism of diatoms is observed in a submarine glaze. A nanometric outer corrosion layer formed by precipitated corrosion products and unspecific organic matter that has been partially degraded to lead and calcium oxalates is found in a glazed tile subjected to an atmospheric environment.

In vitro skin retention and drug permeation study of Tongluo-Qutong rubber plaster by UPLC/UV/MS/MS

Tongluo-Qutong rubber plaster (TQRP), a typical Chinese patent medicine that contains 13 different herbal remedies, is widely used in clinical practice for the treatment of cervical spondylosis and osteoarthritis. However, due to a lack of in vitro transdermal studies, the active ingredients of TQRP have not been fully elucidated. This presents a huge obstacle for quality evaluation, pharmacokinetic studies and clinical safety assessment of TQRP. In this work, a UPLC/UV/MS/MS method was established and validated to evaluate five analytes in TQRP. The validation demonstrated linearity (r > 0.99), specificity (no co-eluting peaks at the retention times of the analytes), and precision (RSD < 15%) within acceptable parameters. A skin permeation study was performed to determine the concentrations of drugs delivered to the dermis. The 24-hour cumulative permeation of ferulic acid, aleo-emodin, emodin and piperine were 303.68, 709.31, 671.06 and 25561.01 ng/cm2, respectively. According to the fitting data of the TQRP active components, skin permeation was mainly due to a combination of passive diffusion and drug release after matrix erosion.

OPTIMIZATION OF DILTIAZEM HYDROCHLORIDE NANOPARTICLES FORMULA AND ITS RELEASE KINETICS EVALUATION

Objective: The purpose of this study was to determine the optimum formula of diltiazem HCl-loaded chitosan nanoparticles due to variations in the speed and duration of stirring and evaluating the release kinetics in vitro using DDSolver.&#x0D; Methods: The method used to prepare nanoparticles is ionic gelation. The ionic gelation method involves an ionic cross-linking between cations on the backbone of chitosan and anion, such as sodium tripolyphosphate (Na TPP). &#x0D; Results: Stirring speed of 1200 rpm and stirring time of 2 h produce an optimum response. The optimum formula has an entrapment efficiency of 71.10%, a particle size of 110.2 nm, and a polydispersity index of 0.268. The dry powder of diltiazem HCl nanoparticles produced a drug loading of 66.14±1.71% and a yield of 34.07±0.73%. The FT-IR showed ionic interaction (cross-linking) between ammonium ions from chitosan and phosphate ions from Na TPP. Scanning electron microscopy (SEM) analysis showed a particle size of 150 µm, a spherical shape, and rough surface morphology. In vitro release profiles indicated prolonged release, which follows the Korsmeyer Peppas model. &#x0D; Conclusion: It can be concluded that increasing the speed and duration of stirring will improve drug entrapment and reduce the particles size variation. The dry nanoparticles release mechanism is by diffusion and matrix erosion.

Drug-releasing Microspheres for Stem Cell Differentiation.

The ability of stem cells to differentiate into specialized cells make them a valuable tool for therapeutic applications. 3D bioprinting, a subset of additive manufacturing, uses bioinks composed of cells and biomaterials to create living tissues. The use of bioactive factors like small molecules and proteins can promote stem cell differentiation into the desired cell phenotypes for tissue regeneration. Small molecules can accelerate the process of regeneration in tissue engineering, maintain bioactivity in a biological environment, and minimize the costs associated with this process. Additionally, they can be encapsulated in specialized drug-delivery devices called microspheres for controlled release. Microspheres are small (1-1000 μm) spherical particles usually made from biodegradable and biocompatible polymers that can be loaded with drugs and other bioactive components. They can then be integrated into stem-cell-laden bioinks used to form bioprinted tissues, where they will release the encapsulated drug and promote differentiation of stem cells into the desired mature cell type. Microspheres can be widely used to encapsulate a broad range of therapeutic agents, including hydrophilic and hydrophobic small molecule drugs, DNA, and proteins. The release of encapsulated molecules occurs through degradation and erosion of the polymer matrix. This article provides detailed protocols for fabricating and sterilizing drug-releasing microspheres made from poly-ε-caprolactone, a promising biodegradable polymer often used for controlled drug delivery due to its biocompatibility and biodegradation kinetics. Additional protocols describe characterization of the loading and size of microspheres as well as incorporation of microspheres into a fibrin-based bioink for 3D bioprinting. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Fabrication of drug-releasing PCL microspheres Support Protocol 1: Preparation of microspheres for determination of encapsulation efficiency by HPLC Support Protocol 2: Preparation of microspheres for SEM analysis Basic Protocol 2: Incorporation of microspheres into fibrin-based bioink.

Curcumin-loaded composite hydrogel based on scallop (Patinopecten yessoensis) male gonad hydrolysates and κ-carrageenan: Characterization and in vitro digestibility

A composite hydrogel composed of scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs) and κ-carrageenan (KC) was fabricated with a designed microstructure to preserve curcumin (Cur) during the upper gastrointestinal tract (GIT). The presence of KC obviously increased the initial elastic moduli (8.2–761.8 Pa), shortened the relaxation time T23 (517.37–420.10 ms) as well as caused the blue shift of the emission peak and quenched the intrinsic fluorescence of Cur in SMGHs/KC-Cur system, signifying the solid combination within SMGHs and KC. In addition, the red shift in O–H stretching bands and blue shift in amide I bands in SMGHs/KC-Cur further accentuated the involvement of hydrogen bonds and electrostatic interactions within SMGHs, KC and Cur. The disappearance of crystalline structures suggested the successful embedment of Cur in the hydrophobic core of SMGHs. Moreover, the microstructure of the hydrogels varied from heterogeneous with tattered large pore cavities and scattered patches to homogeneous distribution with dense mesh and solid network wall. These scenarios caused a more compact network of SMGHs/KC-Cur than SMGHs-Cur to protect Cur from releasing in simulated intestinal and simulated colonic phases with slower released rate, both of which had the final extent of Cur release exceeding 90%. Furthermore, cryo-SEM showed that the significant release of Cur from hydrogels in the simulated intestinal phase was due to SMGHs matrix erosion with even larger pore sizes, tattered network and thinner network wall. Therefore, it is suggested that SMGHs/KC hydrogels with biocompatibility and good tolerance to acid environment could be reliable and desirable soft materials to embed and deliver Cur to the colon, having potential applications in functional foods and biological therapeutic purposes.

Basic Amino Acid-Modified Lignin-Based Biomass Adjuvants: Synthesis, Emulsifying Activity, Ultraviolet Protection, and Controlled Release of Avermectin.

Avermectin (AVM) is a highly effective and safe biopesticide but is very sensitive to ultraviolet (UV) light and exhibits poor water solubility. Developing green and multifunctional adjuvants is important for the protection and controlled release of AVM. In this work, a number of water-soluble enzymatic hydrolysis lignins (W-EHLs) were prepared via grafting basic amino acids and used as emulsifiers with co-surfactants to prepare high-internal phase emulsions (HIPEs). The results showed that W-EHLs with co-surfactants could be prepared with HIPEs that contained 90 vol % green oil phases such as turpentine, and the stability of the HIPEs first increased and then decreased when the rate of grafting of basic amino acids on lignin increased from 0.26 to 1.46 mmol/g. The more polar oil droplets were less deformable due to their higher viscosity, thereby affording a stability advantage to HIPEs. Subsequently, the relations between the stability and interfacial viscoelasticity of the emulsion were effectively correlated by interfacial rheology, droplet size, and physical stability tests. The results showed that HIPEs with smaller droplets had poor fluidity and strong interfacial viscoelasticity due to their higher droplet packing density, which resulted in good macroscopic stability. Like the AVM carrier, the retention rate of AVM in HIPEs was 80.1% after UV radiation for 72 h, which represented the highest UV protection efficiency in AVM delivery systems. The release curves showed that the rate of release of AVM from HIPEs was adjusted by controlling the pH value of the medium. In addition, the release of HIPEs is completely in accord with both diffusion and the matrix erosion mechanism. The strategy could be extended to other sensitive pesticides and used to promote the development of sustainable agriculture.

Impact of Drug Loading Method on Drug Release from 3D-Printed Tablets Made from Filaments Fabricated by Hot-Melt Extrusion and Impregnation Processes.

The purpose of this study was to investigate the impact of the drug loading method on drug release from 3D-printed tablets. Filaments comprising a poorly water-soluble model drug, indomethacin (IND), and a polymer, polyvinyl alcohol (PVA), were prepared by hot-melt extrusion (HME) and compared with IND-loaded filaments prepared with an impregnation (IMP) process. The 3D-printed tablets were fabricated using a fused deposition modeling 3D printer. The filaments and 3D printed tablets were evaluated for their physicochemical properties, swelling and matrix erosion behaviors, drug content, and drug release. Physicochemical investigations revealed no drug–excipient interaction or degradation. IND-loaded PVA filaments produced by IMP had a low drug content and a rapid drug release. Filaments produced by HME with a lower drug content released the drug faster than those with a higher drug content. The drug content and drug release of 3D-printed tablets containing IND were similar to those of the filament results. Particularly, drug release was faster in 3D-printed tablets produced with filaments with lower drug content (both by IMP and HME). The drug release of 3D-printed tablets produced from HME filaments with higher drug content was extended to 24 h due to a swelling-erosion process. This study confirmed that the drug loading method has a substantial influence on drug content, which in turn has a significant effect on drug release. The results suggest that increasing the drug content in filaments might delay drug release from 3D-printed tablets, which may be used for developing dosage forms suited for personalized medicine.

Synthesis, characterizations and kinetics of MOF‐5 as herbicide vehicle and its controlled release in PVA/ST biodegradable composite membranes

AbstractPolyvinyl alcohol/starch based composite membranes containing herbicide‐loaded metal‐organic‐framework (MOF‐5) was successfully synthesized by electrostatic spraying technique. Several main parameters affecting the adsorption of MOF‐5 were studied, including the initial concentration of the herbicide solution, adsorption time, and temperature. Under optimal conditions, herbicide‐loaded MOF‐5 was successfully synthesized and the main properties were characterized by Scanning Electron Microscopy (SEM), X‐Ray Diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR), Thermogravimetric Analysis (TG), and Brunauer‐Emmett‐Teller (BET), respectively. The results showed that the adsorption capacity of MOF‐5 at optimal conditions was 60.12wt%±0.61 % for atrazine. The sustained release effect of the AT@MOF‐5/PVA/ST composite membranes was reliable, and the cumulative release rate was about 50 % for 15 h. The release behaviour of AT from AT@MOF‐5/PVA/ST composite membranes was first dominated by the mechanism of Fickian diffusion and then by the mechanism of matrix erosion. The main advantages of agricultural herbicide film can be attributed to the eco‐friendly, biodegradable, and persistence of herbicide.

Electrically controlled transdermal delivery of naproxen and indomethacin from porous cis-1,4-polyisoprene matrix.

This study is focused on the inquiry of using a porous polymeric structure to absorb and release transdermally two drugs through a skin from deproteinized natural rubber latex (DPNR). The porous DPNR films were fabricated from the internal formation of surfactant micelles and their subsequent leaching out to generate porous structures. The pore size of DPNR films increased with increasing surfactant amount. The model drugs were naproxen and indomethacin; their releases and release-permeations were investigated under the effects of surfactant amount, electrical potential, and drug size. Without electric field, the drug release mechanism was mainly driven by concentration gradient. The higher amount of drug released was obtained from the matrix with a larger pore size. Under electric field, the higher amounts of drug release were obtained in the shorter drug release durations, via the electrorepulsive force between the negatively charged drugs and the cathode electrode. The molecular drug size was a factor for the drug absorption, release rate and amount. For the drug release-permeation experiment through the pig skin, there were two release-permeation periods as governed by the combination of concentration gradient and swelling in the first period, and the matrix erosion in the second period. The fabricated porous DPNR films have been shown here to be potential to be used as a transdermal patch with electrically controllable drug release rate, amount and duration along with the facile drug-matrix loading and absorption.

Histological observation on the initial stage of vascular invasion into the secondary ossification of murine femoral epiphyseal cartilage.

It remains unknown whether the histology of vascular invasion during secondary ossification of epiphyseal cartilage is the same as that seen in primary ossification; we examined the initial processes of vascular invasion of secondary ossification in the murine femora. Many endomucin-immunoreactive blood vessels gathered at the central region of the articular surface, and buds of soft tissue, including glomerular loops of endomucin-immunoreactive blood vessels and TNALPase- immunopositive osteoblastic cells accompanied by TRAP-positive osteoclasts, had begun to invade the epiphyseal cartilage. The invading soft tissues formed cartilage canals displaying MMP9 immunoreactivity in the tip region, and cartilaginous collagen fibrils were not visible in the vicinity of the vascular wall of the blood vessels. Thus, the histological profile marked by invading glomerular vasculature and the erosion of the cartilage matrix near the vascular walls during secondary ossification differs from that seen during primary ossification.

Cavitation erosion behavior of austempered ductile irons of increasing hardness

The cavitation erosion mechanisms of three austempered ductile irons (ADIs) of 279, 333 and 469 Brinell hardness in a heavy-duty engine coolant at 82 °C were described. Sample weight was measured in 14 time steps up to 4 h and complemented by image sequences showing surface damage evolution in detail. A rapid mass loss during the first 1.5 min was attributed to surface graphite erosion, with complete nodule removal within 5 min in all ADIs. Matrix erosion became steady after 30 min, but differed in severity between ADIs, with relative mass loss rates of 4.3 : 1.5 : 1 for ADIs of low, medium and high hardness, respectively.