Exposure Levels and Contributing Factors of Various Arsenic Species and Their Health Effects on Korean Adults.

Arsenic is a human carcinogen. Data on urinary arsenic species analyses of Koreans are limited. This study evaluated the arsenic exposure level, contributing factors, and health effects in Korean adults.

Accelerated biodegradation of iron-based implants via tantalum-implanted surface nanostructures.

In recent years, pure iron (Fe) has attracted significant attention as a promising biodegradable orthopedic implant material due to its excellent mechanical and biological properties. However, in physiological conditions, Fe has an extremely slow degradation rate with localized and irregular degradation, which is problematic for practical applications. In this study, we developed a novel combination of a nanostructured surface topography and galvanic reaction to achieve uniform and accelerated degradation of an Fe implant.

Stable sol-gel hydroxyapatite coating on zirconia dental implant for improved osseointegration.

Aside from being known for its excellent mechanical properties and aesthetic effect, zirconia has recently attracted attention as a new dental implant material. Many studies have focused on hydroxyapatite (HA) coating for obtaining improved biocompatibility, however the coating stability was reduced by a byproduct produced during the high-temperature sintering process. In this study, to overcome this problem, we simply coated the zirconia surface with a sol-gel-derived hydroxyapatite (HA) layer and then sintered it at a varied temperature (<1000 °C).

Construction of tantalum/poly(ether imide) coatings on magnesium implants with both corrosion protection and osseointegration properties.

Poly(ether imide) (PEI) has shown satisfactory corrosion protection capability with good adhesion strength as a coating for magnesium (Mg), a potential candidate of biodegradable orthopedic implant material. However, its innate hydrophobic property causes insufficient osteoblast affinity and a lack of osseointegration. Herein, we modify the physical and chemical properties of a PEI-coated Mg implant.

Enhanced Bioactivity of Micropatterned Hydroxyapatite Embedded Poly(L-lactic) Acid for a Load-Bearing Implant.

Poly(L-lactic) acid (PLLA) is among the most promising polymers for bone fixation, repair, and tissue engineering due to its biodegradability and relatively good mechanical strength. Despite these beneficial characteristics, its poor bioactivity often requires incorporation of bioactive ceramic materials. A bioresorbable composite made of PLLA and hydroxyapatite (HA) may improve biocompatibility but typically causes deterioration in mechanical properties, and bioactive coatings inevitably carry a risk of coating delamination.

PLLA Membrane with Embedded Hydroxyapatite Patterns for Improved Bioactivity and Efficient Delivery of Growth Factor.

Poly(l-lactic) acid (PLLA) is widely used in guided bone regeneration membranes due to its mechanical properties and biodegradability. However, the lack of biocompatibility is a serious disadvantage. Herein, the biocompatibility of PLLA is improved by patterning hydroxyapatite (HA) loaded with recombinant human bone morphogenetic protein-2 (rhBMP-2) under it.

Tantalum-coated polylactic acid fibrous membranes for guided bone regeneration.

Guided bone regeneration (GBR) membrane is necessary to reconstruct the defect bone tissue by defending penetration of soft tissues. Polylactic acid (PLA) attracts much attention to utilize as a GBR membrane because it has relatively high mechanical strength and biodegradability. However, the poor osteoconductivity of PLA is a major concern.

Porous calcium phosphate-collagen composite microspheres for effective growth factor delivery and bone tissue regeneration.

Microspheres are beneficial for filling defects of various shapes and provide a large surface area for cell attachment. Porous microspheres have attracted particular attention because they can deliver cells and bioactive molecules such as growth factors. In this study, BCP-collagen composite microspheres were developed for growth factor delivery in bone regeneration.

Bioactive and mechanically stable hydroxyapatite patterning for rapid endothelialization of artificial vascular graft.

Polymeric vascular grafts have been widely used in the vascular regeneration field because of their ease of application. However, synthetic polymer grafts have the severe problem of low biocompatibility, which may cause delayed endothelialization and hyperplasia. In this study, we fabricated a linear hydroxyapatite (HA) pattern on a silicon wafer and then transferred the pattern to a poly(L-lactic)-acid (PLLA) film for use as a tubular vascular graft.

Enhanced Osseointegration Ability of Poly(lactic acid) via Tantalum Sputtering-Based Plasma Immersion Ion Implantation.

Poly(lactic acid) (PLA) is the most utilized biodegradable polymer in orthopedic implant applications because of its ability to replace regenerated bone tissue via continuous degradation over time. However, the poor osteoblast affinity for PLA results in a high risk of early implant failure, and this issue remains one of the most difficult challenges with this technology. In this study, we demonstrate the use of a new technique in which plasma immersion ion implantation (PIII) is combined with a conventional DC magnetron sputtering.

Use of thioglycerol on porous polyurethane as an effective theranostic capping agent for bone tissue engineering.

Thiolated biodegradable polyurethane (TG-DPU) was synthesized using a one-pot reaction with thioglycerol adopted as a functionalized chain extender. After characterization of the chemical structure of TG-DPU using proton nuclear magnetic resonance spectroscopy, bone morphogenetic protein (BMP-2) was loaded in the TG-DPU under oxidative conditions to form disulfides between the free thiol of TG-DPU and BMP-2. The interaction between TG-DPU and BMP-2, so-called bioconjugates, was investigated using X-ray photoelectron spectroscopy analysis; the appearance of disulfide (S-S) linkage indicated the formation of a polymer/growth factor conjugate system.

In vitro and in vivo evaluation of polylactic acid-based composite with tricalcium phosphate microsphere for enhanced biodegradability and osseointegration.

A biodegradable polylactic acid composite containing tricalcium phosphate microsphere was fabricated. The composite exhibited enhanced biocompatibility and a well-interconnected porous structure that enabled tissue ingrowth after degradation. The tricalcium phosphate microspheres had an average size of 106 ± 43 μm and were incorporated into the polylactic acid matrix using a high-shear mixer.

Hydroxyapatite Microspheres as an Additive to Enhance Radiopacity, Biocompatibility, and Osteoconductivity of Poly(methyl methacrylate) Bone Cement.

This study demonstrates the utility of hydroxyapatite (HA) microspheres as an additive to enhance the radiopaque properties, biocompatibility, and osteoconductivity of poly(methyl methacrylate) (PMMA)-based bone cements. HA microspheres were synthesized using spray drying. They had well-defined spherical shapes, thus allowing for the production of PMMA/HA composites with a very high HA content (20 vol % and 40 vol %).

Calcium Phosphate-Collagen Scaffold with Aligned Pore Channels for Enhanced Osteochondral Regeneration.

This study reports the development of a bilayered scaffold with aligned channels produced via a sequential coextrusion and unidirectional freezing process to facilitate upward bone-marrow stem-cell migration. The biomimetic scaffold with collagen and biphasic calcium phosphate (BCP) layers is successfully fabricated with matching of the cartilage and bone layers. The aligned structure results in an enhancement of the compressive strength, and the channels enable tight anchoring of the collagen layers on the BCP scaffolds compared with a randomly structured porous scaffold.