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1.
J Appl Oral Sci ; 29: e20210089, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34614121

RESUMO

BACKGROUND: Optimal orthodontic force results in maximum rate of tooth movement without tissue damage. Even though starting orthodontic treatment with a thicker archwire may shorten treatment duration, the evidence on the effect of using 0.018-inch NiTi as the first alignment archwire on pulpal blood flow (PBF) status is still scarce. OBJECTIVES: to record PBF changes and pain scores associated with using 0.018-inch NiTi as the first alignment archwire during fixed orthodontic treatment. METHODOLOGY: Patients were selected from subjects attending postgraduate orthodontic teaching clinics at Jordan University of Science and Technology. In total, forty healthy patients who exhibited mild lower arch crowding were included. A split-mouth trial design was used. Each patient received two archwire sizes at one time joined in the midline by crimpable hook and applied in the lower arch. Patients were assigned into one of two groups based on archwire sizes used. Group 1: 0.014-inch and 0.018-inch NiTi (Six males, 14 females aged 19.4±1.33 years) and Group 2: 0.016-inch and 0.018-inch NiTi (Seven males, 13 females aged 19.6±1.45 years). The archwire size group was randomly allocated with a 1:1 allocation ratio. A Laser Doppler Flowmeter was used to measure PBF at different time intervals (T0-T5). Pain scores were recorded using a visual analogue scale (VAS). A repeated measures ANOVA and a post-hoc Bonferroni comparison tests were conducted to examine differences at the different time points before and during orthodontic alignment. RESULTS: For all studied archwire sizes, PBF decreased 20 minutes after their placement. Most PBF changes occurred within 24hours and continued to decrease until 72 hours after archwire placement where the maximum reduction was reached. Eventually, normal values were reverted within 1 month. PBF changes were similar between all alignment - groups. CONCLUSIONS: Initial orthodontic alignment with 0.018-inch NiTi does not cause irreversible changes to pulpal vasculature or produces higher pain scores.


Assuntos
Fios Ortodônticos , Dor , Ligas , Humanos , Estudos Prospectivos
2.
Mater Sci Eng C Mater Biol Appl ; 128: 112266, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34474825

RESUMO

The precipitates in Ti-Ag alloy made an important contribution to antibacterial activity. In order to study this specific effects, Ti-Ag samples with different forms of precipitates were produced by powder metallurgy and ingot metallurgy followed by heat treatment: Ti-Ag(T4) with no precipitate, Ti-Ag(as-cast) and Ti-Ag(T6) with Ti2Ag and Ti-Ag(PM) with Ti2Ag and Ag-rich phase. Microstructure was analyzed by scanning electronic microscope (SEM), and the antibacterial effects, expression of reactive oxygen species (ROS), protein leakage and biocompatibility were investigated by plate count method, staining technology and cell test. The antibacterial ability was in the following order from low to high: Ti-Ag(T4) < Ti-Ag(as-cast) < Ti-Ag(T6) < Ti-Ag(PM). It was elucidated that Ag-containing phase was the major controlling factor of Ti-Ag antibacterial property and Ti-Ag(PM) with micro-size Ti2Ag and Ag-rich phase exhibited high antibacterial activity. It was proposed that the existence of Ag-containing phases induced high expression of ROS in bacteria, which destroyed the homeostasis of the bacteria and eventually leads to the rupture of the bacterial membrane. Cell test indicated that Ti-Ag samples had no adverse effect on cells and had good biocompatibility.


Assuntos
Ligas , Staphylococcus aureus , Ligas/farmacologia , Antibacterianos/farmacologia , Teste de Materiais , Metalurgia , Titânio/farmacologia
3.
Mater Sci Eng C Mater Biol Appl ; 128: 112349, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34474898

RESUMO

Concise, low-cost preparation of titanium alloy implants with high cell proliferation and osteogenic differentiation is urgently needed. Nanosecond laser ablation of titanium alloy has the advantages of short processing time, less pollution, and non-contact. In this research, we adopt a nanosecond UV laser to process the closed groove and cross groove titanium alloys with length to width ratio of 1:1, 2.5:1, 4:1, and 6:1. The surface morphology, surface roughness, phase, element distribution, surface chemistry, and wettability were characterized. The effect of the patterned surface's properties on the adhesion, proliferation, and osteogenic differentiation of stem cells was studied. The results show the laser-ablated lattice structure's surface energy can increase rapidly in the natural environment. The cell adhesion of stem cells on a lattice structure with low roughness and high surface energy is optimal. The element concentration at the ablated edges is higher than at the bottom under Marangoni and surface tension. Stem cells preferentially adhere to the ablated edges with high roughness, element concentration, and hardness. Cell differentiation is chiefly affected by patterning structure. On the surface of the boss structure with a length to width ratio of 2.5:1, the proportion of cell length to diameter is about 2.5, and the cell area is greater. The osteogenic differentiation of cells is the highest on the surface.


Assuntos
Ligas , Titânio , Diferenciação Celular , Proliferação de Células , Lasers , Osteoblastos , Osteogênese , Propriedades de Superfície , Titânio/farmacologia
4.
Niger J Clin Pract ; 24(9): 1373-1379, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34531352

RESUMO

Objectives: The purpose of this study was to investigate the fracture resistance, biocompatibility, hardness, and transverse strength of non-precious metal alloy (chromium-cobalt; Cr-Co), titanium (Ti), zirconia (Zr), polymethylmethacrylate (PMMA), and polyetheretherketone (PEEK) when employed as substructure materials according to the implant supported full arch fixed prosthesis treatment concept. Materials and Methods: In total, 150 Cr-Co, Ti, Zr, PMMA, and PEEK samples (n = 30 per material) measuring 25 × 2 × 2 mm in size were produced. Of the samples, 50 (n = 10 for each material, all having dimensions of 6 × 3 mm) were subjected to biocompatibility tests. The Vickers hardness test and three-point bending test were performed; fracture resistance measurements were taken and the biocompatibility of the samples was evaluated by the XTT assay. Results: Vickers hardness was highest for Zr (p < 0.05). PEEK and PMMA had the lowest (and similar) fracture resistance values (p < 0.05). Cell proliferation on the surfaces of the materials was similar between PEEK and Zr (p > 0.05), which were the most biocompatible materials. Conclusions: Within the limitations of this study, the most favorable materials in terms of biocompatibility were found as PEEK and Zr. When biomechanical properties are evaluated, the most durable materials can be specified as Cr-Co and Zr. Also, further studies are needed to improve material stability.


Assuntos
Ligas , Titânio , Dureza , Testes de Dureza , Teste de Materiais , Próteses e Implantes
5.
Mater Sci Eng C Mater Biol Appl ; 129: 112380, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34579899

RESUMO

Magnesium is a highly promising candidate with respect to its future use as a material for resorbable implants. When magnesium degrades, hydrogen gas is released. High doses of gas emergence are reported to impair osseointegration and may therefore lead to fixation failure. The successful delay and reduction of the degradation rate by applying plasma electrolytic oxidation (PEO) as a post processing surface modification method for magnesium alloy has recently been demonstrated. The aim of this study was thus to compare the degradation behavior of a WE43-based plate system with and without respective PEO surface modification and to further investigate osseointegration, as well as the resulting effects on the surrounding bony tissue of both variants in a miniature pig model. WE43 magnesium screws and plates without (WE43) and with PEO surface modification (WE43-PEO) were implanted in long bones of Göttingen Miniature Pigs. At six and twelve months after surgery, micro-CT and histomorphometric analysis was performed. Residual screw volume (SV/TV; WE43: 28.8 ± 21.1%; WE43-PEO: 62.9 ± 31.0%; p = 0.027) and bone implant contact area (BIC; WE43: 18.1 ± 21.7%; WE43-PEO: 51.6 ± 27.7%; p = 0.015) were increased after six months among the PEO-modified implants. Also, surrounding bone density within the cortical bone was not affected by surface modification (BVTV; WE43: 76.7 ± 13.1%; WE43-PEO: 73.1 ± 16.2%; p = 0.732). Intramedullar (BV/TV; WE43: 33.2 ± 16.7%; WE43-PEO 18.4 ± 9.0%; p = 0.047) and subperiosteal (bone area; WE43: 2.6 ± 3.4 mm2; WE43-PEO: 6,9 ± 5.2 mm2; p = 0.049) new bone formation was found for both, surface-modified and non-surface-modified groups. After twelve months, no significant differences of SV/TV and BV/TV were found between the two groups. PEO surface modification of WE43 plate systems improved osseointegration and significantly reduced the degradation rate within the first six months in vivo. Osteoconductive and osteogenic stimulation by WE43 magnesium implants led to overall increased bone growth, when prior PEO surface modification was conducted.


Assuntos
Magnésio , Osseointegração , Ligas , Animais , Parafusos Ósseos , Suínos , Porco Miniatura
6.
Mater Sci Eng C Mater Biol Appl ; 129: 112387, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34579906

RESUMO

Zinc-based biometal is expected to become a new generation of biodegradable implants. Due to its antibacterial and biocompatibility in vivo, zinc metals is recently considered to be the most promising biodegradable metal, However, cytotoxicity is the thorny problem that currently restrict its application, due to the excessive Zn ions released during degradation. In order to solve these problems, dopamine modified strontium-doped hydroxyapatite coating (SrHA/PDA) was fabricated on alkali-treated pure zinc to improve its corrosion rate and cytocompatibility by electrodeposition for the first time. The obtained coating showed a dense structure and high crystallinity, which was attributed to the attraction of Ca2+ ions by polydopamine. The results showed that the SrHA/PDA coating delayedthe degradation rate of zinc metal, which reduced the release of Zn2+, thereby reducing its cytotoxicity. Additionally, electrochemical tests showed that SrHA/PDA coating can reduce the corrosion rate of pure zinc. In vitro cell viability showed that even at high Zn2+ concentrations (3.11 mg/L), preosteoblasts (MC3T3-E1) cells proliferated at a high rate on SrHA/PDA, thus confirming that Sr2+ counteracted the cytotoxic effects of Zn2+ and promoted cell differentiation. Moreover, the SrHA/PDA coating still maintained excellent antibacterial effects against pathogenic bacterial strains (Escherichia coli and Staphylococcus aureus). Mild pH changes had no significant effect on the viability of cells and bacterias. Collectively, the present study elucidated that by coating SrHA/PDA/Zn(OH)2 on Zn, a controllable corrosion rate, original antibacterial properties and better cell compatibility can be achieved. This provided a new strategy for the surface modification of biodegradable Zn.


Assuntos
Anti-Infecciosos , Zinco , Ligas , Antibacterianos/farmacologia , Materiais Revestidos Biocompatíveis/farmacologia , Corrosão , Dopamina , Hidroxiapatitas , Osteogênese , Estrôncio
7.
Mater Sci Eng C Mater Biol Appl ; 129: 112411, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34579920

RESUMO

Macroporous tantalum (Ta) coating was produced on titanium alloy implant for bone repair by cold spray (CS) technology, which is a promising technology for oxygen sensitive materials. The surface characteristics as well as in vitro cytocompatibility were systematically evaluated. The results showed that a rough and macroporous CS-Ta coating was formed on the Ti6Al4V (TC4) alloy surfaces. The surface roughness showed a significant enhancement from 17.06 µm (CS-Ta-S), 27.48 µm (CS-Ta-M) to 39.21 µm (CS-Ta-L) with the increase of the average pore diameter of CS-Ta coatings from 138.25 µm, 198.25 µm to 355.56 µm. In vitro results showed that macroporous CS-Ta structure with tantalum pentoxide (Ta2O5) was more favorable to induce human bone marrow derived mesenchymal stem cells (HBMSCs) spreading, migration and osteodifferentiation than TC4. Compared with the micro-scaled structure outside the macropores, the surface micro-nano structure inside the macropores was more favorable to promote osteodifferentiation with enhanced alkaline phosphatase (ALP) activity and extracellular matrix (ECM) mineralization. In particular, CS-Ta-L with the largest pore size showed significantly enhanced integrin-α5 expression, cell migration, ALP activity, ECM mineralization as well as osteogenic-related genes including ALP, osteopontin (OPN) and osteocalcin (OCN) expression. Our results indicated that macroporous Ta coatings by CS, especially CS-Ta-L, may be promising for hard tissue repairs.


Assuntos
Células-Tronco Mesenquimais , Tantálio , Ligas , Humanos , Osteogênese , Próteses e Implantes
8.
Mater Sci Eng C Mater Biol Appl ; 129: 112418, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34579927

RESUMO

We have developed a novel bioactive hybrid metallic implant that integrates the beneficial characteristics of a permanent matrix and a biodegradable substance. Such a combination may generate a material system that evolves into a porous structure within weeks to months following implantation and can be used to form strong interfacial bonding and osseointegration for orthopedic and dental applications. Presently, traditional technologies such as casting, powder metallurgy and plastic forming have limited ability to produce the complex bioactive implant structures that are required in practical applications. The present study aimed to develop an innovative bioactive TiMg (BTiMg) hybrid system using a Ti-lattice (Ti-6Al-4 V) produced by an additive manufacturing (AM) process, in combination with a new Mg-based alloy (Mg-2.4%Nd -0.6%Y -0.3%Zr) as a biodegradable filling material. We evaluated the in-vitro behavior of the BTiMg system in a simulated physiological environment, along with cytotoxicity assessment. The microstructure was evaluated by scanning electron microscopy and X-ray diffraction, mechanical properties were examined in terms of compressive strength, environmental performance analysis was conducted by electrochemical testing using potentiodynamic polarization and impedance spectroscopy (EIS), and cytotoxicity characteristics were assessed by indirect cell viability analysis. The results demonstrated the feasibility to produce geometrically complex implants by AM technology, as well as the strength and non-cytotoxic effects of the BTiMg system. Benefits included a relatively high ultimate compressive strength (UCS) and a high yield point (YP), along with an adequate cell viability response in the range between 70 and 120%.


Assuntos
Ligas , Titânio , Osseointegração , Porosidade , Próteses e Implantes
9.
Anal Chem ; 93(38): 13080-13088, 2021 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-34523913

RESUMO

Electrochemical nanotags with controllable and multiresponse electroactivity have a great capacity for overcoming the drawbacks of limited target monitoring and inaccurate detection results for electrochemical sensors. In this contribution, double electro-oxidative Ru and Cu metals were integrated into RuCu nanostructures for the generation of dual electro-oxidative signals. A facial approach was proposed for the controllable fabrication of RuCu cage nanoparticles (NPs) and RuCu alloy NPs by simply adjusting the pH value of the reaction system. RuCu cage NPs and RuCu alloy NPs demonstrated inherent different electro-oxidative responses owing to the remarkable distinction of structures with different metal valences. RuCu cage NPs showed a single electro-oxidization peak at 0.84 V, assigned to the exposure of more Ru0 electroactive sites on the hollow cage structures. RuCu alloy NPs illustrated dual electro-oxidization peak at 0.84 and -0.16 V, attributing to the presence of Ru0 and Cu+ electroactive sites on the alloy structures, respectively. RuCu cage NPs and RuCu alloy NPs served as specific electroactive tags, achieving the selective monitoring of Na2S and ratiometric electrochemical detection of xanthine in monosodium glutamate, respectively. The limits of detection were as low as 27 pM for Na2S and 70 nM for xanthine. The rational design of multimetal nanostructures holds enormous potential for the generation of multiresponse electroactivity with the impetus for exploring the capacity of specific electrochemical sensing.


Assuntos
Nanopartículas , Nanoestruturas , Ligas , Oxirredução
10.
Nano Lett ; 21(19): 8135-8142, 2021 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-34529916

RESUMO

Iron and its alloys have made modern civilization possible, with metallic meteorites providing one of the human's earliest sources of usable iron as well as providing a window into our solar system's billion-year history. Here highest-resolution tools reveal the existence of a previously hidden FeNi nanophase within the extremely slowly cooled metallic meteorite NWA 6259. This new nanophase exists alongside Ni-poor and Ni-rich nanoprecipitates within a matrix of tetrataenite, the uniaxial, chemically ordered form of FeNi. The ferromagnetic nature of the nanoprecipitates combined with the antiferromagnetic character of the FeNi nanophases gives rise to a complex magnetic state that evolves dramatically with temperature. These observations extend and possibly alter our understanding of celestial metallurgy, provide new knowledge concerning the archetypal Fe-Ni phase diagram and supply new information for the development of new types of sustainable, technologically critical high-energy magnets.


Assuntos
Meteoroides , Ligas , Humanos , Ferro , Imãs , Transição de Fase
11.
Int J Mol Sci ; 22(15)2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34361065

RESUMO

Chitosan coatings are deposited on the surface of Mg20Zn magnesium alloy by means of the spin coating technique. Their structure was investigated using Fourier Transform Infrared Spectroscopy (FTIR) an X-ray photoelectron spectroscopy (XPS). The surface morphology of the magnesium alloy substrate and chitosan coatings was determined using Scanning Electron Microscope (FE-SEM) analysis. Corrosion tests (linear sweep voltamperometry and chronoamperometry) were performed on uncoated and coated magnesium alloy in the Hank's solution. In both cases, the hydrogen evolution method was used to calculate the corrosion rate after 7-days immersion in the Hank's solution at 37 °C. It was found that the corrosion rate is 3.2 mm/year and 1.2 mm/year for uncoated and coated substrates, respectively. High corrosion resistance of Mg20Zn alloy covered by multilayer coating (CaP coating + chitosan water glass) is caused by formation of CaSiO3 and Ca3(PO4)2 compounds on its surface.


Assuntos
Ligas/química , Quitosana/química , Materiais Revestidos Biocompatíveis/química , Magnésio/química , Zinco/química , Fenômenos Bioquímicos , Corrosão , Propriedades de Superfície
12.
Science ; 373(6557): 857-858, 2021 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-34413226

Assuntos
Ligas , Magnésio , Corrosão , Humanos
13.
Sensors (Basel) ; 21(16)2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34450947

RESUMO

In this work, an analytical procedure for the preliminary design of shape memory alloy spring-based actuators is investigated. Two static analytical models are considered and interconnected in the frame of the proposed procedure. The first model, based on the works from An, is able to determine the material properties of the SMA components by means of experimental test data and is able to size the SMA component based on the requirements of the system. The second model, based on a work from Spaggiari, helps to design and size an antagonist spring system that allows one to obtain the geometric characteristics of springs (SMA and bias) and the mechanical characteristics of the entire actuator. The combined use of these models allows one to define and size a complex SMA actuator based on the actuation load requirements. To validate the design procedure, static experimental tests have been performed with the entire SMA actuator.


Assuntos
Ligas , Ligas de Memória da Forma , Desenho de Equipamento
14.
BMC Musculoskelet Disord ; 22(1): 734, 2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34452607

RESUMO

BACKGROUND: The repair of large bone defects is a great challenge for orthopedics. Although the development of three-dimensional (3D) printed titanium alloy (Ti6Al4V) implants with optimized the pore structure have effectively promoted the osseointegration. However, due to the biological inertia of Ti6Al4Vsurface and the neglect of angiogenesis, some patients still suffer from postoperative complications such as dislocation or loosening of the prosthesis. METHODS: The purpose of this study was to construct 3D printed porous Ti6Al4V scaffolds filled with bone marrow mesenchymal stem cells (BMSC) and endothelial progenitor cells (EPC) loaded hydrogel and evaluate the efficacy of this composite implants on osteogenesis and angiogenesis, thus promoting osseointegration. RESULTS: The porosity and pore size of prepared 3D printed porous Ti6Al4V scaffolds were 69.2 ± 0.9 % and 593.4 ± 16.9 µm, respectively, which parameters were beneficial to bone ingrowth and blood vessel formation. The BMSC and EPC filled into the pores of the scaffolds after being encapsulated by hydrogels can maintain high viability. As a cell containing composite implant, BMSC and EPC loaded hydrogel incorporated into 3D printed porous Ti6Al4V scaffolds enhancing osteogenesis and angiogenesis to repair bone defects efficiently. At the transcriptional level, the composite implant up-regulated the expression levels of the osteogenesis-related genes alkaline phosphatase (ALP) and osteocalcin (OCN), and angiogenesis-related genes hypoxia-inducible factor 1 alpha (HIF-1α), and vascular endothelial growth factor (VEGF). CONCLUSIONS: Overall, the strategy of loading porous Ti6Al4V scaffolds to incorporate cells is a promising treatment for improving osseointegration.


Assuntos
Osseointegração , Osteogênese , Ligas , Humanos , Porosidade , Impressão Tridimensional , Tecidos Suporte , Titânio , Fator A de Crescimento do Endotélio Vascular
15.
Int J Mol Sci ; 22(16)2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34445794

RESUMO

Xenogeneic biomaterials Cerbone® and OsteoBiol® are widely used in oral implantology. In dental practice, xenogeneic biomaterial is usually combined with autologous bone to provide bone volume stability needed for long-term dental implants. Magnesium alloy implants dissolve and form mineral corrosion layer that is directly in contact with bone tissue, allowing deposition of the newly formed bone. CSBD heals by intramembranous ossification and therefore is a convenient model for analyses of ostoconductive and osteoinductive properties of different type of biomaterials. Magnesium alloy-enriched biomaterials have not yet been applied in oral implantology. Therefore, the aim of the current study was to investigate biological properties of potentially new bovine xenogeneic biomaterial enriched with magnesium alloy in a 5 mm CSBD model. Osteoconductive properties of Cerabone®, Cerabone® + Al. bone, and OsteoBiol® were also analyzed. Dynamics of bone healing was followed up on the days 3, 7, 15, 21, and 30. Calvary bone samples were analyzed by micro-CT, and values of the bone morphometric parameters were assessed. Bone samples were further processed for histological and immunohistochemical analyses. Histological observation revealed CSBD closure at day 30 of the given xenogeneic biomaterial groups, with the exception of the control group. TNF-α showed high intensity of expression at the sites of MSC clusters that underwent ossification. Osx was expressed in pre-osteoblasts, which were differentiated into mature osteoblasts and osteocytes. Results of the micro-CT analyses showed linear increase in bone volume of all xenogeneic biomaterial groups and also in the control. The highest average values of bone volume were found for the Cerabone® + Mg group. In addition, less residual biomaterial was estimated in the Cerabone® + Mg group than in the Cerabone® group, indicating its better biodegradation during CSBD healing. Overall, the magnesium alloy xenogeneic biomaterial demonstrated key properties of osteoinduction and biodegradidibility during CSBD healing, which is the reason why it should be recommended for application in clinical practice of oral implantology.


Assuntos
Ligas/farmacologia , Materiais Biocompatíveis/farmacologia , Osso e Ossos/efeitos dos fármacos , Magnésio/farmacologia , Cicatrização/efeitos dos fármacos , Animais , Regeneração Óssea/efeitos dos fármacos , Substitutos Ósseos/farmacologia , Bovinos , Corrosão , Hidroxiapatitas/farmacologia , Teste de Materiais/métodos , Minerais/farmacologia , Osteoblastos/efeitos dos fármacos , Osteócitos/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Próteses e Implantes , Ratos , Microtomografia por Raio-X/métodos
16.
Talanta ; 234: 122681, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34364481

RESUMO

Hypoxia refers to the lack of oxygen supply to cells or tissues. The overexpression of nitroreductase has been shown to be closely related to the degree of hypoxia, which leads to the level of nitroreductase (NTR) being used as an indicator of hypoxia. We reported a facile visual detection of NTR based on the aggregation of gold and silver alloy nanoparticles. Compared with gold nanoparticles (AuNPs), the aggregation behavior of Au80Ag20 NPs caused a more prominent color change. Copper ions (Cu2+) can be rapidly reduced by nicotinamide adenine dinucleotide (NADH) under the catalysis of Au80Ag20 NPs. But NADH is consumed as an electron donor during the catalytic reduction reaction of p-nitrophenol (pNP) by NTR. A decrease of NADH amount results in the aggregation of Au80Ag20 NPs by the excess Cu2+ and different aggregation degrees of Au80Ag20 NPs lead to observable color change. A linear correlation of A600/A505 = 0.0285 [NTR]+0.361 (R2 = 0.980) was obtained with a limit of detection (LOD) of 0.23 µg/mL for UV-vis spectrophotometer. For visual detection, the values of R/B against the concentration of NTR obtains a calibration curve of R/B = -0.031 [NTR]+ 1.54 (R2 = 0.985) with a LOD of 0.76 µg/mL, which is of the same order of magnitude as the UV-vis spectrophotometer analysis. As a comparison, Au80Ag20 NPs was replaced by several different composition nanoparticles (Au NPs, Au70Ag30 NPs, Au50Ag50 NPs) to be a chromogenic substrate, and the results suggest the Au80Ag20 NPs is the most sensitive substrate in our assay. Selectivity tests showed that the detection system did not respond to other common substances, and the reaction mechanism was verified by inhibitor research. Finally, the assay was used on the human serum samples with spiking NTR, and the recovery rates of this assay with UV-vis spectrophotometer were basically consistent with RGB analysis.


Assuntos
Nanopartículas Metálicas , Prata , Ligas , Colorimetria , Cobre , Ouro , Ligas de Ouro , Humanos , Íons , NAD , Nitrorredutases
17.
Korean J Intern Med ; 36(5): 1204-1210, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34399571

RESUMO

BACKGROUND/AIMS: Multi-drug resistant pathogens are increasing among healthcare-associated infections. It is well known that copper and copper alloys have antimicrobial activity. We evaluated the activity of copper against bacteria in a hospital setting in Korea. METHODS: This study was conducted in a laboratory and medical intensive care unit (ICU). Methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant Enterococcus faecium (VRE) were inoculated onto copper, copper alloy and stainless steel plates. After 24 hours of incubation, colony-forming units (CFU) were counted in the laboratory. Two similar rooms were chosen in the ICU; one room had copper-containing surface, and the other room contained items with a stainless steel surfaces. Items were sampled weekly for 8 weeks when the rooms were not crowded and when the rooms were busier with healthcare workers or visitors. RESULTS: In vitro time-kill curves showed copper or, a copper alloy yielded a significant reduction in MRSA and VRE CFUs over 15 minutes. Upon exposure to stainless steel plates, CFUs were slowly reduced for 24 hours. In vivo, MRSA CFUs were lower in rooms with copper-containing surfaces compared with controls, both after cleaning and after patients had received visitors (p < 0.05). Analysis of VRE revealed similar results, but VRE CFUs from copper-containing surfaces of drug carts in the ICU did not decrease significantly. CONCLUSION: Copper has antimicrobial activity and appears to reduce the number of multi-drug resistant microorganisms in a hospital environment. This finding suggests the potential of the use of copper fittings, instruments and surfaces in hospital.


Assuntos
Infecção Hospitalar , Enterococcus faecium , Infecções por Bactérias Gram-Positivas , Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Ligas , Cobre , Infecção Hospitalar/diagnóstico , Infecção Hospitalar/tratamento farmacológico , Infecção Hospitalar/prevenção & controle , Humanos , Unidades de Terapia Intensiva , Vancomicina
18.
J Mech Behav Biomed Mater ; 123: 104707, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34352487

RESUMO

The requirements for biomedical materials have been raised greatly due to the rapidly aging global population. Shape memory alloys (SMAs) are indeed promising materials for biomedical applications due to their controllable shape deformation via the manipulation of temperature and/or stress. This study investigated the enhancement of the fundamental mechanical properties and the shape memory effect (SME) in the Ti-Cr-based alloys via the modification of Au and Cu. The quaternary Ti-Cr-Au-Cu alloys were successfully manufactured by physical metallurgy methods and their phase constitutions, mechanical properties, SME, and superelastic (SE) behaviors have been investigated in this study. Cold-workability, which was enhanced by the introduction of the Au element, was elaborated by the phase constitutions of the alloys. The ß-parent phase was stabilized to around body temperature by the introduction of the ß-stabilizers of Cr, Au, and Cu, and the functionalities of the specimens were revealed at the operating temperature. Perfect SME at the shape recovery rate of 100% was practiced by the substitution of Au by Cu and the mechanical properties, such as strength and ductility, were also enhanced. Functional mappings of the fundamental mechanical properties, which could be a helpful tool for the investigations of the quaternary Ti-Cr-Au-Cu alloys, were constructed in this work.


Assuntos
Ligas , Titânio , Materiais Biocompatíveis , Teste de Materiais , Metalurgia , Resistência à Tração
19.
Biomed Res Int ; 2021: 5529368, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34368350

RESUMO

The aim of this study was to evaluate the biocompatibility and osteogenic potential of a Zeolite Socony Mobil-5 (ZSM-5) coating on a Ti-24 Nb-4 Zr-7.9 Sn (Ti-2448) surface. ZSM-5-modified Ti-2448 (ZSM-5/Ti-2448) and Ti-2448 (control) groups were employed. The physical and chemical properties of the two types of samples were evaluated by scanning electron microscopy, Fourier-transform infrared spectroscopy, nitrogen adsorption/desorption, and contact angle methods. The surface of the ZSM-5/Ti-2448 was rougher than that of the original Ti-2448, while the contact angle of the ZSM-5/Ti-2448 was smaller than that of Ti-2448. In addition, the ZSM-5/Ti-2448 largely increased the specific surface area and introduced silanol groups. A bone-like apatite layer could be formed on the surface of ZSM-5/Ti-2448 after 14 days of incubation in a simulated body fluid. ZSM-5/Ti-2448 was not cytotoxic. The number and alkaline phosphatase (ALP) activity of osteoblasts on ZSM-5/Ti-2448 were significantly higher than those on Ti-2448 surfaces, obtained in vitro using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide and ALP activity assays. Few inflammatory cells were observed around ZSM-5/Ti-2448 after insertion into the femurs of Japanese white rabbits after 4, 12, and 26 weeks through hematoxylin-eosin staining. The average gray scale of transforming growth factor-ß1 (TGF-ß1) on ZSM-5/Ti-2448 peaked earlier than that on Ti-2448, according to immunohistochemical staining. These results indicate that ZSM-5/Ti-2448 has a good biocompatibility and improved early osteogenic potential compared to a noncoated Ti-2448.


Assuntos
Ligas/farmacologia , Materiais Revestidos Biocompatíveis/farmacologia , Osteogênese/efeitos dos fármacos , Zeolitas/farmacologia , Fosfatase Alcalina/metabolismo , Animais , Biomineralização/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Implantes Experimentais , Masculino , Camundongos , Coelhos , Propriedades de Superfície , Fator de Crescimento Transformador beta/metabolismo
20.
J Mech Behav Biomed Mater ; 123: 104712, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34365098

RESUMO

The Ti-6Al-4V alloy is the most common biomaterial used for bone replacements and reconstructions. Despite its advantages, the Ti-6Al-4V has a high stiffness that can cause stress-shielding. In this work, we demonstrated that the selective laser melting (SLM) technology could be used to fabricate porosity in Ti-6Al-4V extra low interstitial (ELI) to reduce its stiffness while improving cell adhesion and proliferation. With a porosity of 14.04%, the elastic modulus of the porous Ti-6Al-4V ELI was reduced to 80 GPa. The compressive stress and the 3-point-bending flexural tests revealed that the porous Ti-6Al-4V ELI possessed a brittle characteristic. The additional pores within the beams of the lattice structures of porous Ti-6Al-4V ELI increased its surface arithmetic average roughness, Ra = 3.94 µm. The in vitro cytocompatibility test showed that the SLM printing process and the post-processes did not cause any toxicity in the MC3T3-E1 cells. The in vitro cell proliferation test also showed that the porous Ti-6Al-4V ELI increased the proliferation rate of osteogenic induced MC3T3-E1 cells on Day 7. The findings from this study would provide engineers and researchers with both the mechanical information and biological understanding of SLM printed porous Ti-6Al-4V ELI, and SLM printed dense Ti-6Al-4V ELI towards biomedical applications.


Assuntos
Lasers , Titânio , Ligas , Teste de Materiais , Porosidade , Tecnologia
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