Biosensitive and antibacterial coatings on metallic material for medical applications.

Metallic materials are commonly used for load-bearing implants and as internal fixation devices. It is customary to use austenitic stainless steel, especially surgical grade type 316L SS as temporary and Ti alloys as permanent implants. However, long-term, poor bonding with bone, corrosion, and release of metal ions, such as chromium and nickel occur. These ions are powerful allergens and carcinogens and their uncontrolled leaching may be avoided by surface coatings. Therefore, bioactive glasses (BGs) became a vital biomedical material, which can form a biologically active phase of hydroxycarbonate apatite on their surface when in contact with physiological fluids. To reduce the high coefficient of friction and the brittle nature of BGs, polymers are normally incorporated to avoid the high-temperature sintering/densification of ceramic-only coatings. For medical application, electrophoretic deposition (EPD) is now used for polymer (organic) and ceramic (inorganic) components at room temperature due to its simplicity, control of coating thickness and uniformity, low cost of equipment, ability to coat substrates of intricate shape and to supply thick films in composite form, high purity of deposits as well as no phase transformation during coating. Although extensive research has been conducted on polymer/inorganic composite coatings, only some studies have reported multifunctional properties, such as biological antibacterial activity, enhanced cell adhesion, controlled drug release ability, and mechanical properties. This review will focus on biodegradable coatings, including zien, chitosan, gelatin, cellulose loaded with antibacterial drugs/metallic ions/natural herbs on biostable substrates (PEEK/PMMA/PCL/PLLA layers), which have the potential of multifunctional coating for metallic implants.

Carcinogenic hazard assessment of cobalt-containing alloys in medical devices: Review of in vivo studies.

Cobalt (Co) alloys have been used for over seven decades in a wide range of medical devices, including, but not limited to, hip and knee implants, surgical tools, and vascular stents, due to their favorable biocompatibility, durability, and mechanical properties. A recent regulatory hazard classification review by the European Chemicals Agency (ECHA) resulted in the classification of metallic Co as a Class 1B Carcinogen (presumed to have carcinogenic potential for humans), primarily based on inhalation rodent carcinogenicity studies with pure metallic Co. The ECHA review did not specifically consider the carcinogenicity hazard potential of forms or routes of Co that are relevant for medical devices. The purpose of this review is to present a comprehensive assessment of the available in vivo preclinical data on the carcinogenic hazard potential of exposure to Co-containing alloys (CoCA) in medical devices by relevant routes. In vivo data were reviewed from 33 preclinical studies that examined the impact of Co exposure on local and systemic tumor incidence in rats, mice, guinea pigs, and hamsters. Across these studies, there was no significant increase of local or systemic tumors in studies relevant for medical devices. Taken together, the relevant in vivo data led to the conclusion that CoCA in medical devices are not a carcinogenic hazard in available in vivo models. While specific patient and implant factors cannot be fully replicated using in vivo models, the available in vivo preclinical data support that CoCA in medical devices are unlikely a carcinogenic hazard to patients.

Double Mesh Nitinol Stent Versus Self-expanding Stent-graft in Recurrent/Resistant Cephalic Vein Arch Stenoses in Dialysis Fistulae: A Comparative Study.

PURPOSE: To compare the double mesh nitinol stent (DNS) versus the self-expanding stent-graft (SES) in recurrent/resistant cephalic vein arch stenosis in dialysis fistulae. MATERIALS AND METHODS: 17 cases with recurrent/resistant stenosis of the cephalic vein arch treated with a DNS were compared retrospectively with 18 cases treated with an SES. Stenting was performed either for significant recoil post-angioplasty with high-pressure balloons or in recurrent stenoses. Patients were followed up with Doppler ultrasound in our vascular access surveillance programme. Primary and assisted primary patency rates at 3, 6 and 12 months were estimated by Kaplan-Meier analysis. RESULTS: Both stents showed 100% technical success immediately post-stenting, defined as residual stenosis < 30%. 3, 6 and 12 month primary patency of the DNS was 82.4%, 69.7% and 28.1% versus 88.9%, 77.8% and 72.2% for the SES. The DNS had a mean primary patency of 242.4 days compared to 896.3 days for the SES (p = 0.021). 12 month assisted primary patency was 88.2% (DNS) and 100% (SES). The DNS had a mean assisted primary patency of 812 days compared to 1390.3 days for the SES, though this did not reach statistical significance. No stent fractures were identified at 2 years in either group. CONCLUSION: Both stents had 100% technical success with no stent fractures. SES showed statistically significant higher primary patency. Assisted primary patency was also higher, though this did not reach statistical significance.

Colloidal Porous AuAg Alloyed Nanoparticles for Enhanced Photoacoustic Imaging.

Colloidal porous AuAg alloyed nanoparticles (pAuAgNPs) were synthesized by galvanic replacement reaction from Ag nanocubes. pAuAgNPs have a 50 nm exterior diameter and half of their inner space consists of voids that have a bimodal size distribution with peaks at 21 and 8.3 nm. pAuAgNPs showed a plasmonic peak at 750 nm, which was exploited for photoacoustic (PA) imaging. Gold nanorods (AuNRs) were prepared and used as the control; they have a strong plasmonic peak at 720 nm. In in vitro experiments at respective plasmonic peak excitations, pAuAgNPs gave stronger PA signals than AuNRs by 8.9 times per particle and 11.7 times per dosage by exogenous atom. The high surface area per volume as a result of the inner voids amplified the PA signals by efficient thermoacoustic conversion. In experiments of chicken-tissue phantoms, pAuAgNPs showed PA signals through 4.5 cm thick tissue, whereas AuNRs gave no detectable signal. In whole-body in vivo experiments, pAuAgNPs injected into the body showed 2.7 times stronger PA signals than AuNRs. Coating the pAuAgNPs with a silica layer additionally increased their PA signal by 1.8 times when compared to the uncoated ones.

Ability of adhesion and biofilm formation of pathogens of periprosthetic joint infections on titanium-niobium nitride (TiNbN) ceramic coatings.

BACKGROUND: Orthopedic metal implants are notoriously associated with release of metallic ions able to cause biological adverse reactions which might lead to implant loosening and failure. To limit any possible adverse reactions, ceramic coatings for orthopedic metal implants have been introduced. However, information regarding the interaction of these coatings with microbes responsible for periprosthetic joint infections (PJIs) is lacking. Hence, the aim of the present in vitro study is to assess the microbial affinity to a titanium-niobium nitride (TiNbN) coating. METHODS: Adhesion and biofilm formation of clinical isolates of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Cutibacterium acnes were assessed on TiNbN-coated titanium discs in comparison with uncoated titanium and cobalt-chrome alloys discs, with either smooth or rough surfaces. Bacterial adhesion was performed by counting adhered bacteria in the first hours of incubation, and the biofilm formation was performed by means of a spectrophotometric assay and by confocal laser scan microscopy after 72 hours of incubation. RESULTS: Overall, Staphylococcus aureus and Staphylococcus epidermidis, among the most common bacteria responsible for PJIs, displayed a significantly decreased attachment in the first hours of contact and, when cultured in presence of TiNbN coating, in comparison with CoCrMo. Biofilm formation of the four tested strains was comparable on all alloys. CONCLUSIONS: Although the onset of a PJI is more complex than in an in vitro scenario, these findings suggest that TiNbN-coated orthopedic implants do not increase PJIs risk while ameliorating tribological and surface properties could represent a valid choice to limit possible complications such as metal hypersensitivity.

Hemocompatibility of biodegradable Zn-0.8 wt% (Cu, Mn, Li) alloys.

Zinc alloys have been explored as potential materials for biodegradable vascular stents due to their tolerable corrosion rates and tunable mechanical properties. However, the performances of Zn alloys were not supported with enough toxicity or biological compatibility evaluation, particularly hemocompatibility for vascular scaffolding application. In this work, the hemocompatibility of three zinc alloys (Zn-0.8Cu, Zn-0.8Mn and Zn-0.8Li) was evaluated with 316 L stainless steel and pure zinc as controls. The hemolysis ratios of 316 L stainless steel, pure Zn, Zn-0.8Cu, Zn-0.8Mn and Zn-0.8Li were 0.38 ±â€¯0.08%, 1.04 ±â€¯0.21%, 0.47 ±â€¯0.21%, 0.57 ±â€¯0.14% and 0.52 ±â€¯0.22%, respectively, for direct contact method. Platelets aggregation on the 316 L stainless steel was observed, while the adhered platelets on the Zn alloys exhibited round shape with few pseudopodia spreading. The number of adhered platelets on the three zinc alloys (Zn-0.8Cu, Zn-0.8Mn and Zn-0.8Li) had no statistically difference compared with 316 L stainless steel, while significant fewer than the pure Zn group. None remarkable platelet activation, hematocyte aggregation, coagulation or complement activation was observed in any Zn alloy group. Furthermore, the Zn alloys prolonged prothrombin time and partial thromboplastin time, demonstrating a potential function of anticoagulation. The results demonstrated that Zn alloys presented in this work are indeed meeting the hemocompatible requirements of implant and showing the promise for perspective application as biodegradable stent.

The Randomized Freeway Stent Study: Drug-Eluting Balloons Outperform Standard Balloon Angioplasty for Postdilatation of Nitinol Stents in the SFA and PI Segment.

PURPOSE: The prospective randomized multicenter Freeway study evaluated the possible hemodynamic and clinical benefits of primary stent insertion followed by percutaneous transluminal angioplasty (PTA) with drug-eluting balloons (DEB) over post-stent insertion PTA with standard balloons in the treatment of symptomatic femoropopliteal arteriosclerotic lesions. METHODS: In total, 204 patients in 13 centers in Germany and Austria were enrolled and randomized to primary stenting followed by either FREEWAY™ drug-eluting balloon or standard PTA balloon angioplasty. The primary endpoint was the rate of clinically driven target lesion revascularization (TLR) at 6 months; the secondary endpoints include TLR rate at 12 months and primary patency, shift in Rutherford classification, ankle-brachial index (ABI) and major adverse events (MAE) at 6 and 12 months. Lesion characteristics and vessel patency were analyzed by an independent and blinded corelab. RESULTS: At 6-month and 12-month follow-up, TLR rate was lower in the DEB arm compared to standard PTA but did not reach statistical significance (4.1% vs. 9.0% p = 0.234 and 7.9% vs. 17.7% p = 0.064, respectively). Primary patency was significantly better for patients treated with the DEB at 6 months (90.3% vs. 69.8% p = 0.001) and 12 months (77.4% vs. 61.0% p = 0.027). Improvement in Rutherford classifications was likewise significantly better for patients in the DEB group at 6 (94.9% vs. 84.3% p = 0.027) and 12 months (95.5% vs. 79.9% p = 0.003). The percentage of patients with an improved ABI of 1.0-1.2 was significantly higher in the DEB group compared to the PTA group at 6 months (55.3% vs. 35.3%; p = 0.015) but without significant difference at 12 months (48.2% vs. 32.9%; p = 0.055). At 6 months, rate of major adverse events (MAE) was 1% in both arms, and at 12 months 2.2% for the DEB and 3.8% for the PTA group. CONCLUSION: The Freeway Stent Study shows that the usage of DEB as a restenosis prophylaxis seems to be safe and feasible. The 12-month follow-up results give a clear sign in favor of the DEB group.

First-in-man experience of the Versi Retriever in acute ischemic stroke.

OBJECTIVE: To describe our initial experience with the Versi Retriever for mechanical thrombectomy in patients with acute ischemic stroke. METHODS: This study is a single-center, single-arm, first-in-man registry under institutional review board control to evaluate the efficacy and safety of the new stent retriever, the Versi Retriever. Patients with acute ischemic stroke were consecutively enrolled between September and November 2017. The clinical and procedural data were retrospectively analyzed. The angiographic result after the procedure was self-graded based on the Thrombolysis in Cerebral Infarction (TICI) scale by each operator. RESULTS: Eleven patients with a mean age of 69.4 years were treated with the Versi Retriever. Median National Institutes of Health Stroke Scale score on admission was 16 (IQR 10-34). The occluded vessel was located in the anterior circulation in 81.8%. Revascularization rates of TICI 2b-3 and TICI 3 at final angiogram were achieved in 100% and 63.6%, respectively. A favorable functional outcome (modified Rankin Scale 0-2) at 90 days was obtained in 72.7%. No symptomatic intracranial hemorrhage occurred and no procedure-related complication was observed. CONCLUSIONS: Our initial experience suggests that the Versi Retriever is a safe and effective stent retriever for mechanical thrombectomy in patients with acute ischemic stroke. CLINICAL TRIAL REGISTRATION: NCT03366818.

Cost-effectiveness of lung volume reduction coil treatment in patients with severe emphysema: results from the 2-year follow-up crossover REVOLENS study (REVOLENS-2 study).

BACKGROUND: The REVOLENS study compared lung volume reduction coil treatment to usual care in patients with severe emphysema at 1 year, resulting in improved quality-adjusted life-year (QALY) and higher costs. Durability of the coil treatment benefit and its cost-effectiveness at 2 years are now assessed. METHODS: After one year, the REVOLENS trial's usual care group patients received coil treatment (second-line coil treatment group). Costs and QALYs were assessed in both arms at 2 years and an incremental cost-effectiveness ratio in cost per QALY gained was calculated. The uncertainty of the results was estimated by probabilistic bootstrapping. RESULTS: The average cost of coil treatment in both groups was estimated at €24,356. The average total cost at 2 years was €9655 higher in the first-line coil treatment group (p = 0.07) and the difference in QALY between the two groups was 0.127 (p = 0.12) in favor of first-line coil treatment group. The 2-year incremental cost-effectiveness ratio (ICER) was €75,978 / QALY. The scatter plot of the probabilistic bootstrapping had 92% of the replications in the top right-hand quadrant. CONCLUSION: First-line coil treatment was more expensive but also more effective than second-line coil treatment at 2 years, with a 2-year ICER of €75,978 / QALY. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT01822795 .

Contribution of cutlery and serving dishes to the human daily intake of silver An in vitro assessment.

Silver cutlery and serving dishes are a potential source of exposure of humans that was never quantified. Release of silver was assessed in vitro in an acidic solution mimicking food fluid in two conditions: i] the JRC guidelines for hot fill conditions with stable high temperature over a 2 hour-period of time, and ii] a more realistic condition with spontaneous progressive decline from 90̊C to ambient temperature over the same period of time. Massive silver 95% strips were exposed to a 5% citric acid solution: i) cooling down from 90̊C to ambient or ii) 70̊C maintained, during 2 hours. Spectrometry with optical emission was used to measure silver in solution. In the spontaneous cooling down study, the time-course of temperature was close to the Newton's law of cooling and the released quantities were detected but too low to be measured. The 70̊C exposition resulted in a non-linear release that became quantifiable after one hour of heating up to an apparent plateau at 120 min with a mean concentration [extreme] of 24.6 [22.3-26.8] µg/L. The results of the present study allow concluding that 95% silver used for cutlery and serving dishes may be released in foods. However, the extent of release depends on the condition of use. At a stable 70̊C temperature over a 2 h-period of time, silver is released in a non-linear model up to a mean concentration of 24.6 µg/L. In contrast, in conditions fitting with the routine recommendations of use, infinitesimal detectable amounts of silver were released.

Recovery of low volumes of wear debris from rat stifle joint tissues using a novel particle isolation method.

Less than optimal particle isolation techniques have impeded analysis of orthopaedic wear debris in vivo. The purpose of this research was to develop and test an improved method for particle isolation from tissue. A volume of 0.018 mm3 of clinically relevant CoCrMo, Ti-6Al-4V or Si3N4 particles was injected into rat stifle joints for seven days of in vivo exposure. Following sacrifice, particles were located within tissues using histology. The particles were recovered by enzymatic digestion of periarticular tissue with papain and proteinase K, followed by ultracentrifugation using a sodium polytungstate density gradient. Particles were recovered from all samples, observed using SEM and the particle composition was verified using EDX, which demonstrated that all isolated particles were free from contamination. Particle size, aspect ratio and circularity were measured using image analysis software. There were no significant changes to the measured parameters of CoCrMo or Si3N4 particles before and after the recovery process (KS tests, p > 0.05). Titanium particles were too few before and after isolation to analyse statistically, though size and morphologies were similar. Overall the method demonstrated a significant improvement to current particle isolation methods from tissue in terms of sensitivity and efficacy at removal of protein, and has the potential to be used for the isolation of ultra-low wearing total joint replacement materials from periprosthetic tissues. STATEMENT OF SIGNIFICANCE: This research presents a novel method for the isolation of wear particles from tissue. Methodology outlined in this work would be a valuable resource for future researchers wishing to isolate particles from tissues, either as part of preclinical testing, or from explants from patients for diagnostic purposes. It is increasingly recognised that analysis of wear particles is critical to evaluating the safety of an orthopaedic device.

3-Year follow-up of temporary implantable nitinol device implantation for the treatment of benign prostatic obstruction.

OBJECTIVES: To report 3-year follow-up results of the first implantations with a temporary implantable nitinol device (TIND® ; Medi-Tate Ltd., Or Akiva, Israel) for the treatment of lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: In all, 32 patients with LUTS were enrolled in this prospective study. The study was approved by the local Ethics Committee. Inclusion criteria were: age >50 years, International Prostate Symptom Score (IPSS) ≥10, peak urinary flow (Qmax ) <12 mL/s, and prostate volume <60 mL. The TIND was implanted within the bladder neck and the prostatic urethra under light sedation, and removed 5 days later in an outpatient setting. Demographics, perioperative results, complications (according to Clavien-Dindo classification), functional results, and quality of life (QoL) were evaluated. Follow-up assessments were made at 3 and 6 weeks, and 3, 6, 12, 24 and 36 months after the implantation. The Student's t-test, one-way analysis of variance and Kruskal-Wallis tests were used for statistical analyses. RESULTS: At baseline, the mean (standard deviation, sd) patient age was 69.4 (8.2) years, prostate volume was 29.5 (7.4) mL, and Qmax was 7.6 (2.2) mL/s. The median (interquartile range, IQR) IPSS was 19 (14-23) and the QoL score was 3 (3-4). All the implantations were successful, with a mean total operative time of 5.8 min. No intraoperative complications were recorded. The change from baseline in IPSS, QoL score and Qmax was significant at every follow-up time point. After 36 months of follow-up, a 41% rise in Qmax was achieved (mean 10.1 mL/s), the median (IQR) IPSS was 12 (6-24) and the IPSS QoL was 2 (1-4). Four early complications (12.5%) were recorded, including one case of urinary retention (3.1%), one case of transient incontinence due to device displacement (3.1%), and two cases of infection (6.2%). No further complications were recorded during the 36-month follow-up. CONCLUSIONS: The extended follow-up period corroborated our previous findings and suggests that TIND implantation is safe, effective and well-tolerated, for at least 36 months after treatment.

Evaluation of central venous catheters coated with a noble metal alloy-A randomized clinical pilot study of coating durability, performance and tolerability.

The use of Central Venous Catheters (CVCs) commonly results in complications. Coatings with silver or metal alloys can reduce the risk associated with the use of CVC. We have evaluated the durability of a noble metal coated CVC (the Bactiguard Infectious Protection, BIP CVC) and compared with an uncoated CVC for clinical tolerability (Adverse Events, AEs) and performance, in order to create a baseline for a large future study. Patients undergoing major surgery, randomised at a 2:1 ratio to BIP CVC (n = 22) or standard CVC (n = 12), were catheterized 9 - 12 days, respectively. Adverse events, microbial colonization and metal release were measured. FINDINGS: There were no AEs in the BIP CVC-group, but 5 AEs occurred in 4 patients (1 patient had 2 AEs) in the standard CVC-group, p = 0.011 (whereof 3 were catheter related). The BIP CVC showed an initial release of coating metals in blood (gold, silver and palladium), which rapidly decreased and were far below Permitted Paily Exposure (PDE) for chronical use. The levels of silver concentration were far below those needed to develop microbial resistance. The performance was equal, and there was no difference concerning microbial colonization, for the two CVCs. CONCLUSION: In this pilot study the BIP CVC had significantly lower AEs and showed a comparable performance to the standard CVC. The coating was durable throughout the study length (up to 16 days) and toxicological evaluation showed good safety margins. Larger studies are needed. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2337-2344, 2018.

NaK alloy-induced in vivo tumor ablation therapy.

PURPOSE: Alkali metal ablation is newly emerging as an effective, economic and minimally invasive ablation therapy. This study is dedicated to demonstrate the high efficiency of NaK alloy ablation on in vivo tumors with different stages in mice. MATERIAL AND METHODS: Panc02 tumor cells were injected into 21 female C57B/L mice, which were divided into three groups. Two experimental groups of mice received the same percutaneous NaK alloy injection for a week apart. The inner temperature response and surface temperature distribution were measured using a thermal couple and an infrared camera. After each ablation experiment, two mice in each group were chosen randomly to make pathological sections. The tumor volumes were measured once every two days. At the end, all tumors were cut off to calculate the tumor inhibition rates. RESULTS: The NaK alloy-induced ablation therapy produced an obvious temperature increase (85 °C) in the ablation region and the high temperature distribution was relatively concentrated. The histopathology sections showed that developing stage tumors received incomplete destruction of the malignant cells compared with early stage tumors. The tumor inhibition rate in the early and developing tumor treatment groups were 88.5% and 67.6%, respectively. CONCLUSIONS: This technology provides a nearly thorough ablation treatment for early stage tumors and also a palliative treatment for developing tumors.

Effects of bimetallic nanoparticles on seed germination frequency and biochemical characterisation of Eruca sativa.

In the modern era of science and technology, nanotechnology is becoming popular science field because materials at nanoscale contain improved physical, chemical and biological properties. This study aimed to explore the capacity of bimetallic nanoparticle alloys of silver (Ag), copper (Cu), gold (Au) in different ratios to evaluate the effects on medicinally important plant Eruca sativa. Biochemical parameters of Eruca sativa were studied by applying bimetallic alloy nanoparticles. Seeds of Eruca sativa were germinated on Murashige and Skoog medium with various combinations of nanoparticles suspension employed in concentration of (30 µg/ml). Bimetallic alloys were considered as a stress inducing factor in plants while studying the phytotoxicity. Many secondary metabolites were released because defensive mechanism of plants was active in response to stress. Such secondary metabolites produced in medicinal plants have a great capability in treating the human diseases. In the authors' study, nanoparticles of small size and of high toxicity effect produced more secondary metabolites like total protein content, total flavonoids and total phenolic content.

The Effect of File Size and Type and Irrigation Solutions on the Accuracy of Electronic Apex Locators: An In Vitro Study on Canine Teeth.

Measurements of the root canal during endodontic treatment have a significant influence on the course of the therapeutic process as well as on its final result in both human and veterinary medicine. The apical constriction should be the termination point for the preparation and filling of the root canal. This research was conducted with the use of a Septodont kit consisting of a small chamber filled with the examined solution in which a healthy second incisor was placed. The step back method was applied for the root canal preparation and master apical file of 30 was used. The working length was 22 mm. The examination was conducted with the use of steel as well as nickel titanium hand instruments. Different irrigation solutions and two types of apex locators were used. Measurements of the working length of the root canal showed dependence on the size of the instrument. Examinations carried out in various environments showed that analogical measurements were obtained only for sodium hypochlorite solutions. In other environments the measured sections were shortened. Comparative examinations with the use of steel instruments demonstrated insignificant measurement differences. Compared to these results, the measurements in nickel titanium group were characterized by more considerable deviations.

Biodegradable Mg-Cu alloy implants with antibacterial activity for the treatment of osteomyelitis: In vitro and in vivo evaluations.

Treatment of chronic osteomyelitis (bone infection) remains a clinical challenge; in particular, it requires an implantable material with improved antibacterial activity. Here, we prepared biodegradable magnesium (Mg)-copper (Cu) alloys with different Cu contents (0.05, 0.1, and 0.25 wt%) and assessed their potential for treating methicillin-resistant Staphylococcus aureus-induced osteomyelitis. We evaluated the microstructures, mechanical properties, corrosion behavior, and ion release of the alloys in vitro, and their biocompatibility and antibacterial activity in vitro and in vivo. The antibacterial activity of the Mg-Cu alloys in vitro was demonstrated by microbiological counting assays, bacterial viability assays, biofilm formation observations, and the expression of biofilm, virulence, and antibiotic-resistance associated genes. The antibacterial activity of Mg-Cu alloys in vivo was confirmed by imaging examination, microbiological cultures, and histopathology. The biocompatibility of Mg-Cu alloys was confirmed by cell proliferation, vitality, and morphology assays in vitro and Cu(2+) or Mg(2+) ion assays, blood biochemical tests, and histological evaluation in vivo. The alloy containing 0.25 wt% Cu exhibited the highest antibacterial activity among the tested alloys, with favorable biocompatibility. Collectively, our results indicate the potential utility of Mg-Cu alloy implants with 0.25 wt% Cu in treating orthopedic infections.

Enhanced in Vitro and in Vivo Performance of Mg-Zn-Y-Nd Alloy Achieved with APTES Pretreatment for Drug-Eluting Vascular Stent Application.

Bioabsorbable magnesium alloys are becoming prominent as temporary functional implants, as they avoid the risks generated by permanent metallic implants such as persistent inflammation and late restenosis. Nevertheless, the overfast corrosion of Mg alloys under physiological conditions hinders their wider application as medical implant materials. Here we investigate a simple one-step process to introduce a cross-linked 3-amino-propyltrimethoxysilane (APTES) silane physical barrier layer on the surface of Mg-Zn-Y-Nd alloys prior to electrostatic spraying with rapamycin-eluting poly(lactic-co-glycolic acid) (PLGA) layer. Surface microstructure was characterized by scanning electron microscope and Fourier transform infrared spectroscopy. Nanoscratch test verified the superior adhesion strength of PLGA coating in the group pretreated with APTES. Electrochemical tests combined with long-term immersion results suggested that the preferable in vitro anticorrosion behavior could be achieved by dense APTES barrier. Cell morphology and proliferation data demonstrated that APTES pretreated group resulted in remarkably preferable compatibility for both human umbilical vein endothelial cells and vascular smooth muscle cells. On the basis of excellent in vitro mechenical property, the animal study on the APTES pretreated Mg-Zn-Y-Nd stent implanted into porcine coronary arteries confirmed benign tissue compatibility as well as re-endothelialization without thrombogenesis or in-stent restenosis at six-month followup.

Design and development of novel MRI compatible zirconium- ruthenium alloys with ultralow magnetic susceptibility.

In the present study, novel MRI compatible zirconium-ruthenium alloys with ultralow magnetic susceptibility were developed for biomedical and therapeutic devices under MRI diagnostics environments. The results demonstrated that alloying with ruthenium into pure zirconium would significantly increase the strength and hardness properties. The corrosion resistance of zirconium-ruthenium alloys increased significantly. High cell viability could be found and healthy cell morphology observed when culturing MG 63 osteoblast-like cells and L-929 fibroblast cells with zirconium-ruthenium alloys, whereas the hemolysis rates of zirconium-ruthenium alloys are <1%, much lower than 5%, the safe value for biomaterials according to ISO 10993-4 standard. Compared with conventional biomedical 316L stainless steel, Co-Cr alloys and Ti-based alloys, the magnetic susceptibilities of the zirconium-ruthenium alloys (1.25 × 10(-6) cm(3)·g(-1)-1.29 × 10(-6) cm(3)·g(-1) for zirconium-ruthenium alloys) are ultralow, about one-third that of Ti-based alloys (Ti-6Al-4V, ~3.5 × 10(-6) cm(3)·g(-1), CP Ti and Ti-6Al-7Nb, ~3.0 × 10(-6) cm(3)·g(-1)), and one-sixth that of Co-Cr alloys (Co-Cr-Mo, ~7.7 × 10(-6) cm(3)·g(-1)). Among the Zr-Ru alloy series, Zr-1Ru demonstrates enhanced mechanical properties, excellent corrosion resistance and cell viability with lowest magnetic susceptibility, and thus is the optimal Zr-Ru alloy system as therapeutic devices under MRI diagnostics environments.

Pain experience during initial alignment with three types of nickel-titanium archwires: a prospective clinical trial.

OBJECTIVE: To clinically evaluate the pain intensity during the week following initial placement of three different orthodontic aligning archwires. MATERIALS AND METHODS: A consecutive sample of 75 patients requiring upper and lower fixed orthodontic appliances were alternately allocated into three different archwires (0.014-inch superelastic NiTi, 0.014-inch thermoelastic NiTi or 0.014-inch conventional NiTi). Assessments of pain/discomfort were made on a daily basis over the first 7-day period after bonding by means of visual analog scale and consumption of analgesics. The maximum pain score was recorded. The possible associations between age, gender, degree of crowding, and teeth irregularity and the pain intensity were also examined. Demographic and clinical differences between the three groups were compared with chi-square test or analysis of variance (ANOVA) test. RESULTS: No statistically significant differences were found in the pain intensity when the three aligning NiTi archwires were compared (P  =  .63). No significant differences in pain perception were found in terms of gender, age, lower arch crowding, and incisor irregularity. The intake of analgesics was the least in the superelastic NiTi group. CONCLUSION: The three forms of NiTi wires were similar in terms of pain intensity during the initial aligning stage of orthodontic fixed appliance therapy. Gender, age, and the degree of crowding have no effect on the perceived discomfort experienced by patients undergoing fixed orthodontic treatment.