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Bench test for magnesium scaffold
Published in Yoshinobu Onuma, Patrick W.J.C. Serruys, Bioresorbable Scaffolds, 2017
Daniel Lootz, Wolfram Schmidt, Peter Behrens, Klaus-Peter Schmitz, Michael Haude, Ron Waksman
In vitro bench testing to investigate the chronic performance of magnesium scaffolds involve a physiological pulsatile load applied to scaffolds which are implanted into a mock vessel in which a simulated body fluid (SBF) flows. The pH-value of the SBF is controlled to stay in the physiological range, and the integrity of the scaffolds is permanently monitored. The output of the test is the time of the first fracture and the time when the scaffold collapses. Applied to AMS-1, a small increase in scaffolding time was found from uncoated scaffolds to the DREAMS-1G, and the scaffolding time approximately doubled from DREAMS-1G to the latest BIOTRONIK magnesium resorbable scaffold, Magmaris.
Guidelines for Nanosilver-Based Antibacterial Devices
Published in Huiliang Cao, Silver Nanoparticles for Antibacterial Devices, 2017
Loris Rizzello, Pier Paolo Pompa
Concerning the category of naturally inspired polymers, Vimala et al. (2009) fabricated semi-interpenetrating hydrogel networks, based on cross-linked polyacrylamide, by means of a redox polymerisation of N,N-methylenebisacrylamide in the presence of different carbohydrate polymers (i.e. carboxymethyl cellulose, gum acacia and starch). At the same time, the reduction of Ag+ ions entrapped within the polymer chains was performed with NaBH4 (Vimala et al. 2009). The authors found good antibacterial activity of polymers having lower cross-linking networks (as a result of the more pronounced Ag NPs and Ag+ release), while highly cross-linked polymers showed a comparatively lower effect. Ag NP–loaded gelatin hydrogel pads have also been exploited for the production of antibacterial wound dressings (Rattanaruengsrikul et al. 2012). The pads were prepared from a gelatin aqueous solution, combined with increasing concentrations of AgNO3, which has been aged for different periods for reduction to Ag NPs, and finally cross-linked with glutaraldehyde. Analyses of Ag+ release revealed that ca. 50%–60% of silver was released after 24 h of incubation in phosphate-buffered saline (PBS) or simulated body fluid buffer solution. The inhibition assays, based on CFU experiments, confirmed that these pads were strongly effective against both Gram-positive and Gram-negative microorganisms (Rattanaruengsrikul et al. 2012).
Injectable Scaffolds for Bone Tissue Repair and Augmentation
Published in Naznin Sultana, Sanchita Bandyopadhyay-Ghosh, Chin Fhong Soon, Tissue Engineering Strategies for Organ Regeneration, 2020
Subrata Bandhu Ghosh, Kapender Phogat, Sanchita Bandyopadhyay-Ghosh
Cementitious pastes have been used increasingly in minimally invasive bone tissue engineering applications. Calcium phosphate cements (CPCs), mineral trioxide aggregates, in this regard are gaining attention as bone substitutes, due to their injectability and self-setting ability in physiological conditions. CPCs also possess structures similar to biological apatites and often demonstrate excellent bioactivity. Injectable calcium phosphate cements (CPCs) consist of aqueous mixtures of calcium phosphates and other soluble calcium salts. This material exhibit injectability, short and long-term mechanical strength as well as increased compressive strength with an increase in the aging time. These materials also show significant in vitro bioactivity in simulated body fluid (SBF). The intrinsic micropores present in such bone cements also help in passage of nutrients and wastes, which in turn facilitates bone cell proliferation and regeneration (Ginebra 2008). Their ability to stimulate osteoblast proliferation and promote osteoblastic differentiation of the bone marrow stromal cells, make them promising candidates as injectable bone scaffolds (Huan and Chang 2009). Along with injectabilty, the setting parameters (such as setting time, dimensional integrity, resultant toxicity, if any) of such injectable pastes are equally crucial. The selection of setting mechanism, therefore, play vital role in designing the appropriate injectable paste based scaffold. Although, several routes have been attempted for preparing the paste based scaffolds, some of these routes are applicable for pre-set cements only, and therefore, cannot be used for injectable applications. The following section reviews the approaches towards developing paste based injectable scaffolds and their hardening mechanisms.
Toxicological and epidemiological approaches to carcinogenic potency modeling for mixed mineral fiber exposure: the case of fibrous balangeroite and chrysotile
Published in Inhalation Toxicology, 2023
Andrey A. Korchevskiy, Ann G. Wylie
Later, Turci et al. (2009) tested a dissolution of various mineral fibers in a simulated body fluid with a chemical composition resembling the phagolysosomal simulant fluid (PSF). It was demonstrated that the fraction of solubilized ions after 30 days of incubation in a non-stirred system with a pH of 4.5 at 37 °C normalized by fiber mass was 4% for balangeroite vs. 16% for Balangero chrysotile, 9% for Val Malenco chrysotile, and less than 0.5% for Val Lanzo and Val Susa tremolite. The authors concluded that the dissolution pattern of balangeroite is closer to chrysotile than to tremolite, and therefore, balangeroite should be much less biopersistent than amphibole. Turci et al. (2009) suggested that, while their data can only approximate any direct toxicological or epidemiological metrics, the balangeroite occasionally associated with chrysotile in Balangero is not expected to be largely responsible for the health effects observed among workers in the mine. It should be noted that Turci et al. (2009) did not estimate iron release from balangeroite or other minerals in the study. It is easy to see from Table 1 that chrysotile has a significantly lower fraction of iron in its chemical composition than balangeroite, and it is possible that that chemical difference may affect the difference in toxicity.
Topical application of nanoparticles integrated supramolecular hydrogels for the potential treatment of seborrhoeic dermatitis
Published in Pharmaceutical Development and Technology, 2020
Abhinava Garg, Charan Singh, Deepak Pradhan, Goutam Ghosh, Goutam Rath
The skin obtained from goat was used for the ex vivo permeation experiment of the final formulation. Hairs of the skin were shaved carefully. The skin was defatted without disturbing the epidermal surface. The excised skin sample was cleaned and analyzed for integrity and kept at 4 °C for further study. The permeation study was carried out by Franz dilution cell at 32 °C, briefly, the dorsal surface of the skin faced towards the donor chamber, filled with 1 g formulation. Receptor compartment was filled with simulated body fluid comprising of pH 7.4 buffer solutions (Okasaka et al. 2019). The entire setup was positioned on a magnetic stirrer, stirred at 100 rpm throughout the experiment. Five millilitre of the sample was withdrawn from the receptor compartment at a predefined time period between 0 h and 12 h, and an equal volume of fresh medium was transferred after each sampling to maintain the sink conditions. The concentration of ketoconazole and selenium in the receptor site was determined using UV–Vis spectrophotometry and AAS, respectively (Montenegro and Puglisi 2013). The permeability study of each formulation was performed in triplicate and the mean values were reported.
Do in vitro solubility studies on endodontic sealers demonstrate a high level of evidence? A systematic review
Published in Acta Odontologica Scandinavica, 2019
Ankur Razdan, Ana Raquel Benetti, Lars Bjørndal
Another important aspect is the quantity of liquid used in solubility studies, which consequently influences the concentration gradient involved in ion extraction. Different quantities ranging from 2 mL [31] to 160 mL have been used in various studies [29,34]. However, it is very difficult to estimate an amount that is relevant for the clinical reality due to variations in the gradient concentration and transport from the periapical region. There are a few studies that advocate renewal of the immersion solution after a certain period, for example, weekly [22,29,75] or every 15 days [31]. Most studies, however, do not employ such renewal. Only three of the moderate studies had employed renewal of immersion media [21,29,31]. A study from the moderate category, undertaken by Prüllage et al. [34], employed new samples for each time period; however, renewal of immersion media for long observation periods was not performed. To summarize, it is desirable to include a simulated body fluid in realistic quantities in future in vitro solubility studies.