Preparation, characterization, and cytotoxicity evaluation of self-assembled nanoparticles of diosgenin-cytarabine conjugate.

Diosgenin (DG) isolated from yam roots revealed various bioactivities and applications as drug carrier. In the present study, a conjugate of DG with cytarabine (Ara-C) was used to prepare the self-assembled nanoparticles (NPs) of DG-Ara-C by a nanoprecipitation method. Dynamic light scattering (DLS) as well as transmission electron microscopy (TEM) were employed to analyze the size and the morphology of NPs, respectively. The stability and absorption of DG-Ara-C NPs were measured. Additionally, the cytotoxicity of the NPs was determined via MTT assay. The results indicated that the average particle size of DG-Ara-C NPs was around 190 nm with a narrow size distribution (PDI = 0.1). TEM showed that DG-Ara-C NPs had a spherical morphology. Compared to free DG or Ara-C, the self-assembled DG-Ara-C NPs exhibited a better anti-tumor activity against solid tumor cells as well as leukemia cells. In conclusion, DG possesses dual role in the self-assembled NPs of DG-Ara-C conjugate, being as a promising anticancer drug and drug carrier.

Synthesis, anticancer activity and potential application of diosgenin modified cancer chemotherapeutic agent cytarabine.

Diosgenin (DG), a steroidal saponin, is mainly found in yam tubers. DG and its derivatives displayed significant pharmacological activities against inflammatory, hyperlipidemia, and various cancers. DG was selected to modify the cancer chemotherapeutic agent cytarabine (Ara-C) due to its anti-tumor activities as well as lipophilicity. After characterization, the biomembrane affinity and the kinetic thermal processes of the obtained DG-Ara-C conjugate were evaluated by differential scanning calorimetry (DSC). Thin hydration method with sonication was applied to prepare the DG-Ara-C liposomes without cholesterol since the DG moiety has the similar basic structure with cholesterol with more advantages. Dynamic Light Scattering (DLS) analysis and cytotoxic analysis were employed to characterize the DG-Ara-C liposomes and investigate their biological activities, respectively. The results indicated that DG changed the biomembrane affinity of Ara-C and successfully replaced the cholesterol during the liposome preparation. The DG-Ara-C liposomes have an average particle size of around 116 nm with a narrow size distribution and revealed better anti-cancer activity against leukemia cells and solid tumor cells than that of free DG or Ara-C. Therefore, it can be concluded that DG displayed the potential application as an anti-cancer drug carrier to improve the bio-activities, since DG counted for a critical component in modulating the biomembrane affinity, preparation of liposome, and release of hydrophilic Ara-C from lipid vesicles.

Wear Behavior of the Human Enamel Antagonist to Different Glazed Zirconia.

In this study, the wear behavior of glazed zirconia was investigated to the antagonist with human enamel after simulated mastication. Twenty Y-TZP specimens were divided into 4 groups: untreated zirconia (Z), glazed zirconia with IPS e.max Ceram (GZE), glazed zirconia with VITA AKZENT® Plus (GZV), and glazed zirconia with glass (GZG). Glazing glass was mainly composed of SiO2, B2O3, Al2O3, Na2O and K2O (nearly 91 wt%). The surface roughness of the specimens was evaluated using roughness profiler. The maxillary premolar teeth were selected as the antagonist. The wear of human enamel against human enamel was used as a control. Five-disc specimens per group were subjected to chewing stimulation CS-4 (SD Mechatronic GmbH, Germany) for 240,000 cycles against human enamel. The wear loss of antagonistic teeth was calculated using a three-dimensional profiling system and the volume loss of the tooth was scanned using a 3D scanner. 3D data obtained before and after testing were overlapped using 3D software (Dentacian Software, EZplant, Korea). The wear loss of glazed zirconia GZE, GZV and GZG groups showed significantly lower than that of human enamel. Whereas, the zirconia (Z) group exhibits significantly lower volume loss than glazed zirconia and enamel. These results show that the wear of the glazing glass is comparable to other commercial glazing materials. Glazing materials are both more susceptible to wear the antagonist relative to zirconia.

Evaluation of Cure Depth and Geometrical Overgrowth Depending on Zirconia Volume Fraction Using Digital Light Processing.

The optical properties of zirconia photopolymer suspension for DLP (Digital Light Processing) were evaluated. The light source and intensity were set to 395 nm and 30 mW/cm². Experimental groups were divided into 48, 50, 52, 54, 56 and 58 vol% according to the zirconia volume fraction. The cure depth of all groups was at least 47.35 um when cured for 1 sec, which was higher than layer parameter values of the 3D printer. The geometrical overgrowth showed 28.55% at 48 vol% and 36.94% at 58 vol%. As the volume fraction of zirconia increased, the geometrical overgrowth increased and the cure depth reduced.

Antibacterial Activity and Fibroblast Cell Viability of Zirconia Coated with Glass Ceramic Containing Ag and NaF Nanoparticles.

The aim of this study was to evaluate the antibacterial activity against Streptococcus mutans and fibroblast viability of zirconia coated with glass ceramic powder containing Ag and F nanoparticles. Specimens were divided into eight groups depending on the glass ceramic powders: 5, 10, 15, 20 wt% of NaF and Ag, respectively. Adhesion of Streptococcus mutans on glass-coated zirconia surface was evaluated by antimicrobial test. Fibroblast viability was examined by WST-8 assay. In result, the bacterial activity was reduced by 11.8%, 15.4% in Ag 10 wt% and 20 wt% groups. When 5~15 wt% of NaF was added, bacterial counts decreased to 4.2~65.4%, and when 20 wt% of NaF was added, the number of bacteria increased by 29.4%. Regardless of Ag and NaF content, all zirconia specimens showed cell viability above 70%. Within the limitations of this study, zirconia coated with glass ceramics powder containing Ag and NaF was found to reduce the adhesion of Streptococcus mutans but had no influence on osteoblast activation.

Evaluation of the Fitness of Glass-Infiltrated Zirconia Core in Maxillary Central Incisor.

The purpose of this study was to evaluate the fitness of zirconia cores according to the amount and treated surface of glass infiltration. A maxillary right central incisor customized abutment was milled to have a 6° slope and a 1 mm deep chamfer margin and was manufactured in an intaglio mold using silicone impression material. Fifty-six stone dies were produced by injecting high strength dental stone into a mold and then zirconia cores were milled with CAD/CAM systems. The control group (Control) used non glass-infiltrated zirconia, and the experiment group was divided by one with the glass and distilled water ratio of 1:300 and the other with the ratio of 1:100. Each group was divided into subgroups by glasstreated surface: external surface infiltration, internal surface infiltration, and both surface infiltration. The zirconia cores sintered after glass infiltration were attached to the stone dies and then cut. Afterwards, the absolute marginal discrepancies and internal gaps of the buccal and lingual sides were measured. The buccal absolute marginal discrepancies and lingual internal gaps were influenced by the glass infiltration amount (p < 0.05); while fitness of zirconia core were not affected by the glasstreated surface (p > 0.05). As a result of the above experiments, the glass-infiltrated zirconia cores showed a clinically acceptable fitness, which is within 120 µm. This means that glass infiltration can be clinically used.

Design, synthesis of methotrexate-diosgenin conjugates and biological evaluation of their effect on methotrexate transport-resistant cells.

A series of methotrexate-diosgenin conjugates was designed and synthesized to enhance the passive internalization of methotrexate (MTX) into transport-resistant cells. The inhibitory effects of these conjugates on dihydrofolate reductase (DHFR), and their anti-proliferation behaviors against a transport-resistant breast cancer cell line, MDA-MB-231, were investigated. All of the synthesized conjugates retained an ability to inhibit DHFR after the diosgenin substitution. The MTX conjugates were much more potent against methotrexate-resistant MDA-MB-231 cells than MTX. Conjugate 18, containing a disulfide bond, exhibited the most potent anti-proliferative and DHFR inhibitory effects (IC50=4.1µM and 17.21nM, respectively). Anti-proliferative activity was higher in the conjugate with a longer space linker (conjugate 21) than those with shorter linkers (conjugates 19 and 20). These results suggest that diosgenin conjugation of MTX may be an effective way to overcome its transport resistance in cancer cells.

Behavior of Osteoblast-Like Cells on a ß-Tricalcium Phosphate Synthetic Scaffold Coated With Calcium Phosphate and Magnesium.

OBJECTIVES: Tricalcium phosphate (TCP) is one of the most useful synthetic scaffolds for bone grafts and has several advantages. However, the rapid degradation of TCP makes it less osteoconductive than the other candidates, and represents a major shortcoming. To overcome this problem, the authors investigated magnesium (Mg) and/or hydroxyapatite (HA) coating on a ß-TCP substrate using a sputtering technique. METHODS: Biocompatibility tests were carried out on ß-TCP discs that were either uncoated (TCP), coated with HA by radio frequency magnetron sputtering (HA-TCP), coated with Mg by DC sputtering (Mg-TCP), or multicoated with Mg and HA by DC and radio frequency magnetron sputtering (MgHA-TCP). RESULTS: Cells showed similar morphology in all 4 groups, and were widely spread, had flattened elongated shapes, and were connected to adjacent cells by pseudopods. An MTT assay revealed higher cell proliferation on HA-TCP, Mg-TCP, and MgHA-TCP compared with TCP at 3 and 5 days. MgHA-TCP also showed significantly higher alkaline phosphatase activity levels compared with TCP, HA-TCP, and Mg-TCP (P < 0.05). CONCLUSIONS: Results suggest that Mg-coated ß-TCP could have great potential as a bone graft material for future applications in hard tissue regeneration.

Effect of magnesium and calcium phosphate coatings on osteoblastic responses to the titanium surface.

PURPOSE: The aim of this study was to evaluate the surface properties and in vitro bioactivity to osteoblasts of magnesium and magnesium-hydroxyapatite coated titanium. MATERIALS AND METHODS: Themagnesium (Mg) and magnesium-hydroxyapatite (Mg-HA) coatings on titanium (Ti) substrates were prepared by radio frequency (RF) and direct current (DC) magnetron sputtering.The samples were divided into non-coated smooth Ti (Ti-S group), Mg coatinggroup (Ti-Mg group), and Mg-HA coating group (Ti-MgHA group).The surface properties were evaluated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The surface roughness was evaluated by atomic force microscopy (AFM). Cell adhesion, cell proliferation and alkaline phosphatase (ALP) activity were evaluated using MC3T3-E1 cells. Reverse transcription polymerase chain reaction (RT-PCR) analysis was performed. RESULTS: Cross-sectional SEM images showed that Mg and Mg-HA depositionson titanium substrates were performed successfully. The surface roughness appeared to be similaramong the three groups. Ti-MgHA and Ti-Mg group had improved cellular responses with regard to the proliferation, alkaline phosphatase (ALP) activity, and bone-associated markers, such as bone sialoprotein (BSP) and osteocalcin (OCN) mRNA compared to those of Ti-S group. However, the differences between Ti-Mg group and Ti-MgHA group were not significant, in spite of the tendency of higher proliferation, ALP activity and BSP expression in Ti-MgHA group. CONCLUSION: Mg and Mg-HAcoatings could stimulate the differentiation into osteoblastic MC3T3-E1 cells, potentially contributing to rapid osseointegration.

Effect of transition metal dopants on mechanical properties and biocompatibility of zirconia ceramics.

In this study, the effect of transition metal dopants, originally added as colouring agents, on the mechanical properties and biocompatibility of sintered zirconia was investigated. This study confirmed that transition metal dopants could have a slight detrimental effect on the mechanical properties of zirconia. The addition of metal dopants did not affect the adhesion and proliferation of gingival fibroblasts.

Response of fetal rat calvarial cells to nanotubular titanium oxide surface.

This study examined the cell response to a TiO2 nanotubular surface (Ti-NT) for future biomedical applications. The level of cell attachment and spreading at 20 min and 60 min was evaluated by SEM. IL-6 and PGE2 secretion was evaluated by ELISA. In SEM analysis, the Ti-NT surface had more fully spread cells compared to the machined titanium surface (Ti-S). ELISA revealed that the level of IL-6 and PGE2 production was higher on the Ti-NT than on the Ti-S. These results suggest that a surface treatment with a nanotubular TiO2 surface enhances the early osteoblast responses, such as cell spreading and cytokine release, which are important for subsequent cell functions and bone healing in vivo.

The effect of low fresh gas flow rate on sevoflurane consumption.

BACKGROUND: In an era of medical cost containment, cost-effectiveness has become a major focus in healthcare. The effect of a new policy on the use of low fresh gas flow during maintenance of general anesthesia with volatile anesthetics was evaluated. METHODS: The numbers and duration of general anesthesia cases using sevoflurane 5 weeks prior to and 15 weeks after policy implementation were retrieved from the electronic medical records database. The number of sevoflurane bottles consumed was also assessed. The anesthesia hours per bottle of sevoflurane were compared before and after policy implementation. RESULTS: The number of anesthesia hours performed per bottle of sevoflurane increased by 38.3%. The effect varied over time and tended to fade with time. CONCLUSIONS: The implementation of a low fresh gas flow rate policy effectively reduces the amount of sevoflurane consumed for the same duration of anesthesia.

The effect of nanotubular titanium surfaces on osteoblast differentiation.

The biological response of fetal rat calvarial cells on a TiO2 nanotubular surface (Ti-NT) was evaluated by cell viability assay, alkaline phosphatase (ALP) activity and reverse transcription polymerase chain reaction (RT-PCR) analysis. The cell viability assay showed no significant difference between the Ti-NT and smooth titanium surfaces (Ti-S). Ti-NT had better cellular responses with regard to the ALP activity and bone-associated markers, such as bone sialoprotein and osteocalcin mRNA than Ti-S. These results suggest that Ti-NT stimulate the differentiation into osteoblasts of fetal rat calvarial cells, potentially contributing to rapid osseointegration.

Anodic oxidized nanotubular titanium implants enhance bone morphogenetic protein-2 delivery.

Implant failure has been attributed to loosening of an implant from the host bone possibly due to poor osseointegration. One promising strategy for improving osseointegration is to develop a functional implant surface that promotes osteoblast differentiation. In this study, a titanium (Ti) surface was functionalized by an anodic oxidation process and was loaded with recombinant human bone morphogenetic protein-2 (rhBMP-2). The following four groups of Ti surfaces were prepared: machined (M), anodized machined (MA), resorbable blast medium (RBM), and anodized RBM (RBMA). The surfaces were characterized by scanning electron microscopy and contact angle measurements. The results showed that a Ti oxide layer (TiO(2)) was observed in the anodized surfaces in the form of nanotubes, approximately 100 nm in diameter and 500 nm in length. The hydrophilic properties of the anodized surfaces were significantly improved. The adsorbed rhBMP-2 loaded on the nonanodized surfaces and lyophilized showed spherical particle morphology. However, the adsorbed rhBMP-2 showed a dispersed pattern over the anodized surfaces. The velocity of the rhBMP-2 released from the surfaces was measured to determine if the anodized surface can improve in delivery efficiency. The results showed that the release velocity of the rhBMP-2 from the anodized surfaces was sustained when compared with that of the nonanodized surfaces. In addition, the rhBMP-2 released from the surface was found to be bioactive according to the alkaline phosphatase activity and the level of calcium mineral deposition. These results suggest that the TiO(2) nanotubular structure formed by anodizing is a promising configuration for sustained rhBMP-2 delivery.

Fabrication and characterization of functionally graded nano-micro porous titanium surface by anodizing.

The purpose of this study was to fabricate and characterize nanotubular structure on machined titanium (MA) and resorbable blast media (RBM) treated titanium by anodizing. The anodized MA and RBM were characterized with scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy disperse spectra, X-ray photoelectron spectra, and nano-indentation and scratch test. Highly ordered nanotubular layers of individually 100 nm in diameter and 500 nm in length approximately were formed regardless of the substrates. The nanotubular layers consisted mainly of amorphous TiO(2) with trace fluorine. The nanotubular surfaces on both the substrates significantly reduced water contact angles and elastic modulus compared with those prior to anodizing. The anodizing treatment significantly increased the surface roughness of the smooth MA, but significantly decreased the surface roughness of the roughened RBM. The critical delamination forces of the nanotubular layer were not obtained due to the limitation of surface roughness. The anodized RBM consisted of a nano-micro porous graded structure, or a nanotubular amorphous fluoride containing TiO(2) layer on top of micro-roughened titanium surface, which is expected to significantly improve the surface area that can be used to deliver drugs and growth factors and alleviate the interfacial elastic modulus mismatch as to enhance osseointegration when compared with conventional dental and orthopedic implant devices with smooth or acid etched surface.