metal ion release
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Gels ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 54
Author(s):  
Laura Riva ◽  
Angelo Davide Lotito ◽  
Carlo Punta ◽  
Alessandro Sacchetti

Herein we report the synthesis of cellulose-based metal-loaded nano-sponges and their application as heterogeneous catalysts in organic synthesis. First, the combination in water solution of TEMPO-oxidized cellulose nanofibers (TOCNF) with branched polyethyleneimine (bPEI) and citric acid (CA), and the thermal treatment of the resulting hydrogel, leads to the synthesis of an eco-safe micro- and nano-porous cellulose nano-sponge (CNS). Subsequently, by exploiting the metal chelation characteristics of CNS, already extensively investigated in the field of environmental decontamination, this material is successfully loaded with Cu (II) or Zn (II) metal ions. Efficiency and homogeneity of metal-loading is confirmed by scanning electron microscopy (SEM) analysis with an energy dispersive X-ray spectroscopy (EDS) detector and by inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis. The resulting materials perform superbly as heterogeneous catalysts for promoting the reaction between aromatic aldehydes and alcohols in the synthesis of aromatic acetals, which play a fundamental role as intermediates in organic synthesis. Optimized conditions allow one to obtain conversions higher than 90% and almost complete selectivity toward acetal products, minimizing, and in some cases eliminating, the formation of carboxylic acid by-products. ICP-OES analysis of the reaction medium allows one to exclude any possible metal-ion release, confirming that catalysis undergoes under heterogeneous conditions. The new metal-loaded CNS can be re-used and recycled five times without losing their catalytic activity.


Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 147
Author(s):  
Johanna Wall ◽  
Didem Ag Seleci ◽  
Feranika Schworm ◽  
Ronja Neuberger ◽  
Martin Link ◽  
...  

While the toxicity of metal-based nanoparticles (NP) has been investigated in an increasing number of studies, little is known about metal-based fibrous materials, so-called nanowires (NWs). Within the present study, the physico-chemical properties of particulate and fibrous nanomaterials based on Cu, CuO, Ni, and Ag as well as TiO2 and CeO2 NP were characterized and compared with respect to abiotic metal ion release in different physiologically relevant media as well as acellular reactivity. While none of the materials was soluble at neutral pH in artificial alveolar fluid (AAF), Cu, CuO, and Ni-based materials displayed distinct dissolution under the acidic conditions found in artificial lysosomal fluids (ALF and PSF). Subsequently, four different cell lines were applied to compare cytotoxicity as well as intracellular metal ion release in the cytoplasm and nucleus. Both cytotoxicity and bioavailability reflected the acellular dissolution rates in physiological lysosomal media (pH 4.5); only Ag-based materials showed no or very low acellular solubility, but pronounced intracellular bioavailability and cytotoxicity, leading to particularly high concentrations in the nucleus. In conclusion, in spite of some quantitative differences, the intracellular bioavailability as well as toxicity is mostly driven by the respective metal and is less modulated by the shape of the respective NP or NW.


Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3446
Author(s):  
Mohammed Zahedul Islam Nizami ◽  
Veena W. Xu ◽  
Iris X. Yin ◽  
Ollie Y. Yu ◽  
Chun-Hung Chu

Nanoparticles based on metal and metallic oxide have become a novel trend for dental use as they interfere with bacterial metabolism and prevent biofilm formation. Metal and metal oxide nanoparticles demonstrate significant antimicrobial activity by metal ion release, oxidative stress induction and non-oxidative mechanisms. Silver, zinc, titanium, copper, and magnesium ions have been used to develop metal and metal oxide nanoparticles. In addition, fluoride has been used to functionalise the metal and metal oxide nanoparticles. The fluoride-functionalised nanoparticles show fluoride-releasing properties that enhance apatite formation, promote remineralisation, and inhibit demineralisation of enamel and dentine. The particles’ nanoscopic size increases their surface-to-volume ratio and bioavailability. The increased surface area facilitates their mechanical bond with tooth tissue. Therefore, metal and metal oxide nanoparticles have been incorporated in dental materials to strengthen the mechanical properties of the materials and to prevent caries development. Another advantage of metal and metal oxide nanoparticles is their easily scalable production. The aim of this study is to provide an overview of the use of metal and metal oxide nanoparticles in caries prevention. The study reviews their effects on dental materials regarding antibacterial, remineralising, aesthetic, and mechanical properties.


2021 ◽  
Vol 12 (2) ◽  
pp. 401-415
Author(s):  
Henryk Matusiewicz ◽  
Magdalena Richter

There is public concern over the long term systemic health effects of metal released from implanted medical devices that use metal alloys. Systemic toxic side effects have been associated with excessive metal ion release from implants into human biological specimen's circulation, in which cobalt and chromium plays an important role. Cobalt intoxication has become more frequent due to the wide use of metallic medical implants. Despite the technological improvements in replacement metallic medical implants, wear and corrosion products associated with the metal compounds of these implants may result in systemic reactions and toxicities. The current review encompasses a literature of the systemic toxicity studies concerning the effect of metallic wear debris released from wear and corrosion of specific types of implanted medical devices, resulting in a postoperative increase in metal ion levels in bodily fluids and at different organ sites. Release of metallic debris is mainly in the form of particles and ions of different valences, and oxides composed of cobalt and chromium. Toxicological, clinically significant, data regarding "potential hazards" of circulating metals after systemic chronic exposure to the metal ions from metals have been included. This review further highlights some of the clinical features of cobalt toxicity.


Author(s):  
A. Pautasso ◽  
I. Zorzolo ◽  
E. Bellato ◽  
P. Pellegrino ◽  
A. Ferrario ◽  
...  

Abstract Purpose Metal ion release may cause local and systemic effects and induce hypersensitivity reactions. The aim of our study is first to determine if implant-related hypersensitivity correlates to patient symptoms or not; second, to assess the rate of hypersensitivity and allergies in shoulder arthroplasty. Methods Forty patients with shoulder replacements performed between 2015 and 2017 were studied with minimum 2-year follow-up; no patient had prior metal implants. Each patient underwent radiographic and clinical evaluation using the Constant-Murley Score (CMS), 22 metal and cement haptens patch testing, serum and urine tests to evaluate 12 metals concentration, and a personal occupational medicine interview. Results At follow-up (average 45 ± 10.7 months), the mean CMS was 76 ± 15.9; no clinical complications or radiographic signs of loosening were detected; two nickel sulfate (5%), 1 benzoyl peroxide (2.5%) and 1 potassium dichromate (2.5%) positive findings were found, but all these patients were asymptomatic. There was an increase in serum aluminum, urinary aluminum and urinary chromium levels of 1.74, 3.40 and 1.83 times the baseline, respectively. No significant difference in metal ion concentrations were found when patients were stratified according to gender, date of surgery, type of surgery, and type of implant. Conclusions Shoulder arthroplasty is a source of metal ion release and might act as a sensitizing exposure. However, patch test positivity does not seem to correlate to hypersensitivity cutaneous manifestations or poor clinical results. Laboratory data showed small constant ion release over time, regardless of gender, type of shoulder replacement and implant used. Levels of evidence Level II.


2021 ◽  
Vol 12 (10) ◽  
pp. 768-780
Author(s):  
Francesco Manfreda ◽  
Egzon Bufi ◽  
Enrico Florio ◽  
Paolo Ceccarini ◽  
Giuseppe Rinonapoli ◽  
...  

2021 ◽  
Vol 11 (Suppl. 1) ◽  
pp. 167-175
Author(s):  
Hakkı Yılmaz ◽  
Fundagül Bilgiç Zortuk ◽  
Ali Tuncay Özyılmaz

Aim: Materials used in orthodontic treatment can cause corrosion and metal ion release to the mouth. This study was aimed to examine the changes in the friction coefficients and corrosion resistance of the modified Ni-Ti arch wires. Methodology: Our sample consisted of 16 Ni-Ti arch wires (0.016 × 0.022 inches). Coating bathes involving Ni-Ti, Ni-Ti-Mo, and Ni-Ti-Cr were prepared for arch wires coating. New surfaces were analyzed by SEM, and the crystallographic structure was determined by X-rays. The friction coefficient of the coated wires was determined by nanoindentation. Artificial saliva was prepared as a corrosive condition. Impedance measurements were performed with an electrochemical analyzer. The AC impedance spectroscopy measurements were performed after four hours, seven, 15, 30, 45, and 60 days. Results: All groups were more resistant than the control group (-447 mV) [group 1 (-388 mV), group 2 (-328 mV), group 3 (-327 mV), group 4 (-427 mV), group 5 (-395 mV), group 6 (-366 mV), and group 7 (-380 mV)]. Friction coefficients of group 5 (0.252) and group 6 (0.265) were observed to be lower than those of the control group (0.288). Conclusion: In the results of our study, it was shown that the surface properties of Ni-Ti wires could be electrochemically improved. The coated wires (group 5 and group 6) had a remarkable corrosion resistance and reduced friction. The protocols that we used should help provide better-quality surfaces.   How to cite this article: Özyılmaz AT, Bilgiç Zortuk F, Yılmaz H. Evaluation of the surface properties of modified ni-ti arch wires. Int Dent Res 2021;11(Suppl.1):167-176. https://doi.org/10.5577/intdentres.2021.vol11.suppl1.25   Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.  


2021 ◽  
pp. 030157422110373
Author(s):  
Prasad Chitra ◽  
GS Prashantha ◽  
Arun Rao ◽  
Harshvardhan S Jois

Introduction: Fluoride agents to prevent white spot lesions are used often during orthodontic treatment. The beneficial effects of fluoride, when consumed within permissible limits on dental structures, are well known. Their implications on underlying biological tissues, however, are unknown. Mouthwashes and dentifrices with fluorides are associated with metal ion release into the mouth with possible cell genotoxicity. Since these cariostatic agents are frequently used during orthodontic therapy, a deeper understanding of the effects of fluoride on oral tissues was considered necessary. Methodology: Three groups of patients (30 each)—group 1 (untreated controls), group 2 (non-fluoridated), and group 3 (Fluoridated) were analyzed. Patients in groups 2 and 3 were bonded with the same bracket prescription and treated with similar archwire sequences. Buccal mucosal cells at 4 specific time periods (before treatment, 1 week, 30 days, and 6 months) were collected, using a wooden tongue depressor, and assessed for any nuclear abnormalities. Comparisons of changes were made with an untreated control group and also between the non-fluoridated and fluoridated groups. Relevant conclusions were drawn after analysis of the results. Results: Greater number of nuclei were observed at the 30-day time interval in the fluoridated group, which was statistically significant at P < .001. Conclusion: Use of fluoridated oral hygiene products in patients undergoing fixed orthodontic treatment with NiTi archwires could increase the risk of micronuclei formation in buccal mucosal cells.


2021 ◽  
Vol 108 (Supplement_6) ◽  
Author(s):  
H Khatkar ◽  
M Prokopenko

Abstract Aim In vitro knee simulation has demonstrated favourable wear properties and decreased metal ion release of ceramic coated metal femoral components in total knee arthroplasty surgery. Femoral implants coated with ceramic have been used in patients, however the subsequent clinical performance and time-to-revision of these implants is largely unknown. The scope of this study was to review the current available clinical literature, focusing on retrieval studies of Ceramic-Coated TKAs. Method Literature review of PubMed and MEDLINE. All studies included demonstrated clinical evaluation of implant performance, either in vivo or at revision. Results 9 studies were identified and included for analysis in this study. Retrieval analysis has illustrated microscopic defects in coatings of revised implants, with associated abrasion and 3rd body wear of the polyethylene component. Evidence suggests that coating femoral components with ceramic can prevent effective cement bonding, leading to aseptic loosening and thus earlier implant failure. Despite these problems, high volume centres have been able to demonstrate comparable results when compared with traditional bearing surface combinations. The mechanism behind metal ion hypersensitivity is currently poorly understood; however, the use of ceramic coated knee replacements is demonstrating a reduction in metal ion release. Conclusions Whilst conferring favourable clinical properties in certain instances, the lack of surgical, implant and patient data surrounding the use of this coated implants remains concerning. The literature base remains limited, and meaningful clinical conclusions cannot be drawn. Recommendations include performing robust clinical trials in order to delineate the clinical efficacy of ceramic coatings in knee arthroplasty.


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