Porous Chitosan/Hydroxyapatite Composite Microspheres for Vancomycin Loading and Releasing.

Porous chitosan/hydroxyapatite (Chi-HAp) composite microspheres were prepared in an aqueous solution containing chitosan, calcium nitrate, and ammonium dihydrogen phosphate by using a hydrothermal method at various temperatures. The investigation indicated that temperature significantly impacted the final product's appearance. Hydroxyapatite (HAp) coupled with dicalcium phosphate dihydrate (DCPD) flakes were obviously found at 65 and 70 °C, while the latter gradually disappeared at higher temperatures.

The Preparation and Characterization of Chitosan/Calcium Phosphate Composite Microspheres for Biomedical Applications.

In this study, we successfully prepared porous composite microspheres composed of hydroxyapatite (HAp), di-calcium phosphate di-hydrated (DCPD), and chitosan through the hydrothermal method. The chitosan played a crucial role as a chelating agent to facilitate the growth of related calcium phosphates. The synthesized porous composite microspheres exhibit a specific surface area of 38.

Heparin-Loaded Composite Coatings on Porous Stent from Pure Magnesium for Biomedical Applications.

Challenges associated with drug-releasing stents used in percutaneous transluminal coronary angioplasty (PTCA) encompass allergic reactions, prolonged endothelial dysfunction, and delayed stent clotting. Although absorbable stents made from magnesium alloys seem promising, fast in vivo degradation and poor biocompatibility remain major challenges. In this study, zirconia (ZrO) layers were used as the foundational coat, while calcium phosphate (CaP) served as the surface layer on unalloyed magnesium specimens.

Effects of Adding Chitosan on Drug Entrapment Efficiency and Release Duration for Paclitaxel-Loaded Hydroxyapatite-Gelatin Composite Microspheres.

Hydroxyapatite-gelatin microspheres with cone-like pores were synthesized via the wet-chemical method using ammonium dihydrogen phosphate ((NH)HPO) and calcium nitrate (Ca(NO)·4HO) as a source of calcium and phosphate ions with the addition of gelatin, which proved to be more osteoconductive than commercial products, such as fibrin glue and Osteoset Bone Graft Substitute. Following the method of the previous study for loading paclitaxel (PTX), a drug entrapment efficiency of around 58% was achieved, which is much lower than that of the doxorubicin (DOX)-loaded one. Since PTX is hydrophobic while DOX is hydrophilic, the order of chitosan processing and addition of the solvent were tuned in this study, finally leading to an increase in drug entrapment efficiency of 94%.

Effects of Chitosan on Loading and Releasing for Doxorubicin Loaded Porous Hydroxyapatite-Gelatin Composite Microspheres.

Porous hydroxyapatite-gelatin (Hap-Gel) composite microspheres derived by wet chemical methods were used as carriers of doxorubicin (DOX) coupled with chitosan (Chi) for treating cancers. Through X-ray diffraction, specific surface area porosimetry, chemisorption analysis and inductively coupled plasma mass spectrometry, the crystalline phase, composition, morphology, and pore distribution of HAp-Gel microspheres were all characterized. HAp nanosized crystals and Gel polymers form porous microspheres after blending and exhibit a specific surface area of 158.

Dynamic Polarization Behaviors of Equimolar CoCrFeNi High-Entropy Alloy Compared with 304 Stainless Steel in 0.5 M HSO Aerated Aqueous Solution.

Three corrosion potentials and three corrosion current densities are clearly identified before the passivation for both dynamic polarization curves of equimolar CoCrFeNi high-entropy alloy (HEA) and 304 stainless steel (304SS) in 0.5 M HSO aerated aqueous solution, by decomposing anodic and cathodic polarization curves. The passivated current density of the former is greater than the latter, compliant with not only the constant of solubility product (k) and redox equilibrium potential () of each metal hydroxide but also the sequence of bond energy () for monolayer hydroxide on their facets derived from the first principle founded on density function theory.

Multiple Transitions in Permalloy Half-Ring Wires with Finite-Size Effect.

Six permalloy (Py) half-rings with finite-size from 120 nm to 360 nm were connected in series on five corners. The magnetization reversal processes were investigated by the measurement of anisotropic magnetoresistance (AMR). The number of switching jumps in the AMR loops, from zero to five, varied with the longitudinal applied field.

Doxorubicin - chitosan - hydroxyapatite composite coatings on titanium alloy for localized cancer therapy.

The doxorubicin-chitosan composite is deposited electrochemically on the Ti alloy post hydroxyapatite coated for reducing the side effects by sustaining release of drugs localized near the tumor to achieve the inhibition or apoptosis of cancer. The possibility of danger in case of exfoliation of medicine composite and HA agglomerates from the alloy surface due to the dynamic erosion of blood flow could be overcome with the additional surface modification by the electrochemical deposition way. The cathodic polarization tests coupled with electrochemical reactions were analyzed to speculate the deposition mechanism of doxorubicin, spectrophotometer (UV visible spectrometer) to measure doxorubicin loading and release, field emission scanning electron microscope (FESEM) to observe surface morphology, Fourier transform infrared (FTIR) spectroscopy for chemical bonding of composites, and X-ray diffractometry (XRD) for crystal structure.

Paclitaxel/hydroxyapatite composite coatings on titanium alloy for biomedical applications.

In order to reduce the side effects of chemotherapy, target therapies have been spotlighted. In this study, paclitaxel, the drug for cancer treatment, is electrochemically deposited on Ti alloy as vascular stents for the tumor localized therapy by sustaining drug releasing to achieve the cancer cells apoptosis or the prevention of cancer metastasis. In the experiment, cathodic polarization tests coupled with electrochemical reactions were analyzed to speculate the deposition mechanism, and the field emission scanning electron microscope (FESEM), focused ion beam (FIB) system and Fourier transform infrared spectroscopy (FTIR) to observe the surface morphology and analyze constituent elements.

Preparation and characterization of gelatin-hydroxyapatite composite microspheres for hard tissue repair.

Gelatin-hydroxyapatite composite microspheres composed of 21% gelatin (G) and 79% hydroxyapatite (HA) with uniform morphology and controllable size were synthesized from a mixed solution of Ca(NO3)2, NH4H2PO4 and gelatin by a wet-chemical method. Material analyses such as X-ray diffraction (XRD), scanning/transmission electron microscopy examination (SEM/TEM) and inductively coupled plasma-mass spectroscopy (ICP-MS) were used to characterize G-HA microspheres by analyzing their crystalline phase, microstructure, morphology and composition. HA crystals precipitate along G fibers to form nano-rods with diameters of 6-10nm and tangle into porous microspheres after blending.

Novel target genes responsive to apoptotic activity by Ocimum gratissimum in human osteosarcoma cells.

Osteosarcoma (OS) is a type of bone cancer. Eighty percent of this tumor will metastasize to the lungs or liver, and as a result, patients generally need chemotherapy to improve survival possibility. Recently, antitumor activity has been reported in Ocimum gratissimum aqueous extract (OGE), which has been the focus of recent extensive studies on therapeutic strategies due to its antioxidant properties.

Vancomycin-chitosan composite deposited on post porous hydroxyapatite coated Ti6Al4V implant for drug controlled release.

Through the hydrogen bonds and the deprotonation, the vancomycin-chitosan composite has been originally deposited on Ti4Al4V by electrochemical technology. However, the rapid destruction of the hydrogen bonding between them by polar water molecules during immersion tests revealed 80% drug burst in a few hours. In this study, the post porous hydroxyapatite (HA) coated Ti4Al4V is prepared for the subsequent electrolytic deposition of vancomycin-chitosan composite to control the drug release.

Protein kinase C alpha location and the expression of phospho-MEK and MDR1 in hepatitis virus-related hepatocellular carcinoma biopsies.

The purpose of this study was to elucidate the function of protein kinase C (PKC) alpha in human hepatocellular carcinoma (HCC). Histoimmunopathologic techniques were used to determine the localization and/or expression of PKCalpha, phospho-mitogen-acrivated protein kinase (MEK) and multidrug resistance 1 (MDR1) in HCC biopsies. Expression of PKCalpha, phospho-MEK and MDR1 was significantly increased in the region of HCC location compared with the non-tumor location.

Characterization and bond strength of electrolytic HA/TiO2 double layers for orthopaedic applications.

Insufficient bonding of juxtaposed bone to an orthopaedic/dental implant could be caused by material surface properties that do not support new bone growth. For this reason, fabrication of biomaterials surface properties, which support osteointegration, should be one of the key objectives in the design of the next generation of orthopaedic/dental implants. Titanium and titanium alloy have been widely used in several bioimplant applications, but when implanted into the human body, these still contain some disadvantages, such as poor osteointegration (forming a fibrous capsule), wear debris and metal ion release, which often lead to clinical failure.

Characterization and bond strength of electrolytic HA/TiO2 double layers for orthopedic applications.

Insufficient bonding of juxtaposed bone to an orthopedic/dental implant could be caused by material surface properties that do not support new bone growth. For this reason, fabrication of biomaterials surface properties, which support osteointegration, should be one of the key objectives in the design of the next generation of orthopedic/dental implants. Titanium and titanium alloy have been widely used in several bioimplant applications, but when implanted into the human body, these still contain some disadvantages, such as poor osteointegration (forming a fibrous capsule), wear debris and metal ion release, which often lead to clinical failure.