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Methods for Characterization of Bioactivity Using Confocal Microscopy *
Published in Mary Anne S. Melo, Designing Bioactive Polymeric Materials for Restorative Dentistry, 2020
Jirun Sun, Joy P. Dunkers, Sheng Lin-Gibson, Nancy J. Lin
Ethoxylated bisphenol-A dimethacrylate (EDMA, degree of ethoxylation ≈ 6), was obtained from Esstech, Inc. Camphorquinone (CQ) and ethyl 4-N,N-dimethylaminobenzoate (4E) were purchased from Aldrich Corp. All reagents were used as received. The resin monomer was activated with a redox photoinitiator system consisting of 0.2% CQ and 0.8% 4E (by mass), and stored in the dark until use. Sodium chloride crystals were ground into small particles using a mortar and pestle and then separated into defined size ranges using brass sieves.
Biotransformation of Monoterpenoids by Microorganisms, Insects, and Mammals
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Yoshiaki Noma, Yoshinori Asakawa
The metabolic pathway of (+)-camphor (37) by microorganisms is shown in Figure 22.189. (+)-Camphor (37) is metabolized to 3-hydroxy- (243), 5-hydroxy- (235), 6-hydroxy- (228), and 9-hydroxycamphor (225) and 1,2-campholide (237). 6-Hydroxycamphor (228) is degradatively metabolized to 6-oxocamphor (229) and 4-carboxymethyl-2,3,3-trimethylcyclopentanone (230), 4-carboxymethyl-3,5,5-trimethyltetrahydro-2-pyrone (231), isohydroxycamphoric acid (232), isoketocamphoric acid (233), and 3,4,4-trimethyl-5-oxo-trans-2-hexenoic acid (234), whereas 1,2-campholide (237) is also degradatively metabolized to 6-hydroxy-1,2-campholide (238), 6-oxo-1,2-campholide (239), and 5-carboxymethyl-3,4,4-trimethyl-2-cyclopentenone (240), 6-carboxymethyl-4,5,5-trimethyl-5,6-dihydro-2-pyrone (241), and 5-carboxymethyl-3,4,4-trimethyl-2-heptene-1,7-dioic acid (242). 5-Hydroxycamphor (235) is metabolized to 6-hydroxy-1,2-campholide (238), 5-oxocamphor (236), and 6-oxo-1,2-campholide (239). 3-Hydroxycamphor (243) is also metabolized to camphorquinone (244) and 2-hydroxyepicamphor (245) (Bradshaw et al., 1959; Conrad et al., 1961, 1965a,b; Gunsalus et al., 1965; Chapman et al., 1966; Hartline and Gunsalus, 1971; Oritani and Yamashita, 1974) (Figure 22.189).
A Guide to Esthetic Treatment After Whitening
Published in Linda Greenwall, Tooth Whitening Techniques, 2017
The manufacturers of composite materials have responded to requests for providing lighter and whiter shades of composites to match the new shades of whiter teeth. To do so, manufacturers have had to make some changes to the composite formulations. It may be that to achieve bright white or translucent shades of resins, some manufacturers find it necessary to use less camphorquinone or another photoinitiator altogether (Neumann et al. 2005). Photoinitiators such as 1-phenyl-1,2-propanedione (PPD) are photosensitizers of potential value in reducing color problems associated with visible light-cured dental resins. In combination with camphorquinone, they act synergistically to produce a more efficient photoinitiation reaction. Other composite-related factors in the whitener shade composites include shade, translucency, and filler particle size, load, and distribution. Light-related factors include light intensity, spectral distribution, and exposure time. In a study by Gomes et al. (2006), different light-emitting diode (LED) lights were used to polymerize a whitening shade resin composite, and compared with a conventional Optilux 501 light. It was hypothesized that the LED lights would not be able to effectively polymerize this specific resin composite. According to the results, the hardness values of LED 2 were similar to the values observed when the halogen light was used. There appears to be a good correlation between decreasing degree of conversion and decreasing hardness, fracture toughness, and abrasive wear resistance. To compensate for the lower hardness values found, the duration of exposure can be increased, within practical limits determined by the properties of the material and light source, providing enhanced opportunity for creation of free radicals.
Controlled release of bioactive IL-2 from visible light photocured biodegradable elastomers for cancer immunotherapy applications
Published in Pharmaceutical Development and Technology, 2022
Mohamed A. Shaker, Jules J. E. Doré, Husam M. Younes
A known amount of IL-2 solid particles with different TH/BSA mass ratios were dissolved in PBS in triplicate. The solutions of each TH/BSA mass ratio were divided into three equal aliquots. The first aliquot was used to examine the effect of photocuring on IL-2 bioactivity. A 10% ethanolic solution of both camphorquinone and triethanolamine (equivalent to 0.01% (w/v)) was added, and the solution was exposed to a visible light source (450–550 nm at a 40 mW/cm2) at a distance of 10 cm for 10 min. The second aliquot was lyophilized to assess the lyophilization effect, and the obtained solid was re-dissolved in sterile water. Finally, to access the freezing and thawing cycles on protein stability, the third aliquot was frozen at −85 °C for the next 24 h and then thawed at room temperature. These solutions were then added to a CTLL-2 cell culture to assess the bioactivity of IL-2.
Monowave and polywave light-curing of bulk-fill resin composites: degree of conversion and marginal adaptation following thermomechanical aging
Published in Biomaterial Investigations in Dentistry, 2021
Sheila Celia Mondragón Contreras, Ana Luiza Barbosa Jurema, Evaniele Santos Claudino, Eduardo Bresciani, Taciana Marco Ferraz Caneppele
In some bulk-fill RCs, camphorquinone (CQ), which is the most common photoinitiator in conventional RCs, is also used [12]. First and second-generation light-emitting diode (LED) light-curing units (LCUs) show one emission peak (monowave, MW) that matches the absorption spectrum of CQ (430–500 nm) [16]. However, such LCUs may not provide adequate cure of RCs containing alternative initiators. Tetric N-Ceram Bulk Fill (TB) contains Ivocerin, a photoinitiator characterized by high quantum efficiency and high absorption capacity. This germanium-based initiator system has a greater photo-curing activity than CQ. The absorption peak of Ivocerin is set in the violet spectrum (380–420 nm) and slightly extends to the blue spectrum range (420–455 nm), where almost 50% of its peak absorbance occurs at 440 nm. Ivocerin is a photoinitiator with higher photopolymerization reactivity [17]. The third-generation LED LCUs are considered to be broad-spectrum devices. They have two or more emission peaks (polywave, PW) with narrower wavelengths; violet to activate alternative photoinitiators and blue to activate CQ [18].
Influence of resin cement on color stability of ceramic veneers: in vitro study
Published in Biomaterial Investigations in Dentistry, 2021
Maryam Hoorizad, Sara Valizadeh, Haleh Heshmat, Seyedeh Farnaz Tabatabaei, Tahereh Shakeri
Archegas et al. [21] showed that cements had a yellowish discoloration following aging, which was in line with our findings. Similarly in our study, all samples showed yellowish discoloration after AAA and this color shift towards yellow was much greater in the resin cement groups compared to the groups with ceramic veneers. In other words, ceramic veneers masked a high percentage of yellowish discoloration of cements. Evidence shows that yellowish discoloration of samples after aging can be due to the presence of camphorquinone in cement formulation. Also, this yellowish discoloration can be due to the presence of Bis-GMA in the cement subjected to UV light radiation and heat. Moreover, degradation of residual amines and oxidation of unreacted carbon double bonds are among other reasons for yellowish discoloration of samples [19,22]. On the other hand, presence of UDMA in the composition of cement may be associated with lower percentage of TEGDMA and can lead to less water sorption and subsequently less discoloration [16]. In the present study, the b* parameter significantly increased in both cement groups and this increase was greater in Variolink cement group. This may be due to its lower filler percentage compared to Choice 2 [18,21]. The percentage of yellowish discoloration was significantly less in laminate veneering groups. In other words, laminate veneers can mask the color change of resin cements to some extent such that the amount of color change in Choice 2 group with ceramic veneers was within the clinically acceptable range. Nonetheless, the color change of resin cements would still be visible at the margins of ceramic veneers.