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Silica Nanoparticles for Drug Delivery
Published in Vladimir Torchilin, Handbook of Materials for Nanomedicine, 2020
With the goal of generating a stimuli-responsive pulsatile delivery system, Villalonga and co-workers used a lactose-modified esterase to cap the pores of loaded MSN through boronic acid cyclic ester bonds with the lactose residues. Release could be triggered in two waves: displacement of the lactose with D-glucose leading to partial uncapping of the pores, then acid-induced cleavage of the boronic acid cyclic esters with addition of ethyl butyrate, which is converted to a butyric acid by the esterase and decreases the local pH. Both result in removal of the neoglycoesterase from the MSN and thus uncapping of the pores. Some leakage was observed in HeLa cells, which is attributed to the slightly acidic microenvironment hydrolyzing some of the ester bonds, but overall the DOX-loaded carriers were non-cytotoxic in the absence of trigger molecules. Treatment with D-glucose induced moderate cell death while ~50% of cells were either dead or in the process of cell death after the addition of ethyl butyrate [77].
Experimental Description of Chemical Reactions
Published in John Andraos, Reaction Green Metrics, 2018
Preparation of 5-(4-Chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxylic Acid (6). A mixture of 4-(4-chloro phenyl)-3-methyl-2, 4-dioxo-ethyl butyrate (3, 8.0 g, 1 mol), ethanol (200 mL), 2,4-dichlorophenyl hydrazine (6.2 g, 1 mol), and 50% sulfuric acid (80.0 mL) was heated to reflux for 4–6 h. On completion of reaction (TLC), the solvent was removed under reduced pressure, the second lot of 50% sulfuric acid (160 mL) was added, and the mixture was heated to reflux for 6–8 h. On completion of reaction (TLC), the mixture was cooled to 25–35°C, and the reaction mass was poured into ice-water (200 mL), stirred about 15 min, filtered, washed with water (80 mL), and dried under vacuum for about 2 h. A mixture of the wet solid and water (220 mL) was stirred about 10 min at ambient temperature, adjusted to pH 10–12 with caustic lye (2.2 mL), and washed with petroleum ether. The aqueous layer was separated, adjusted to pH 2 with 12 N hydrochloric acid (2.0 mL), and stirred about 15 min at 25–35°C. The Solid material was filtered, washed with water (1000 mL), and dried at 35°C to constant weight to afford 5-(4-chlorophenyl)-1-(2,4-dichloro phenyl)-4-methyl-1 H-pyrazole-3-carboxylic acid (6, 7.7 g, 70%).
Cellulose Nitrate
Published in Allan F. M. Barton, and Solubility Parameters, 2018
Fuchs and Suhr29 compiled information, including water as a solvent for 6.8% nitrogen material. For 10.5 to 12% N, solvents were reported as: lower alcohols, acetone, amyl acetate, ethylene glycol ethers, glacial acetic acid, and alcohol/diethyl ether. Nonsolvents included higher alcohols, higher carboxylic acids, higher ketones, and tricresyl phosphate. In the case of 12.7% nitrogen, solvents were halogenated hydrocarbons, acetone, methyl amyl ketone, cylcohexanone, methyl acetate, ethyl acetate, ethyl butyrate, ethyl lactate, ethylene glycol ether acetates, ethylene carbonate, furan derivatives, nitrobenzene, and ethanol/diethyl ether. Aromatic hydrocarbons and higher alcohols caused swelling; nonsolvents were aliphatic hydrocarbons, lower alcohols, ethylene glycol, diethyl ether, dilute carboxylic acids, and water.
In vitro and in vivo acute toxicity of an artificial butter flavoring
Published in Journal of Toxicology and Environmental Health, Part A, 2023
Nárcia Mariana Fonseca NUNES, Jurandy do Nascimento SILVA, Micaely Lorrana Pereira CONCEIÇÃO, Joaquim Soares da COSTA JÚNIOR, Edymilais da Silva SOUSA, Maria das Dores Alves de OLIVEIRA, Antonia Maria das Graças Lopes CITÓ, Dalton DITTZ, Ana Paula PERON, Paulo Michel Pinheiro FERREIRA
Ethyl butanoate was the main chemical of the butter flavoring. It is also called ethyl butyrate or butyric ether (C6H12O2, 116.1 g/mol) and is a volatile ethyl carboxylic ester resulting from formal condensation of the hydroxy group of ethanol with the carboxy group of butyric acid. Ethyl butanoate plays a role as a plant metabolite and is functionally related to ethanol, being responsible for aromas including apple-like (Niu et al. 2019), pineapple (Wei et al. 2011), and cheeses (Qian and Reineccius 2003; Wang et al. 2020) and is found in sweet rice (Yang et al. 2021) and Qingke liquor alcoholic beverages (Qian et al. 2019). It appears as a clear colorless liquid, is less dense than water and not soluble in water and glycerol, but soluble in fixed oils and propylene glycol (FAO/UN 2022; Riemenschneider and Bolt 2005). Interestingly, ethyl butanoate was found to be the major constituent of the butter flavoring, contrasting with most studies describing the compound diacetyl (2,3-butanedione) as the main α-diketone out of 100 chemicals found in buttery-like additives and responsible for the buttery aroma in microwave popcorn, cookies (Boylstein et al. 2006; Brass and Palmer 2017; Brazil 2012; Martyny et al. 2008), coffee (LeBouf et al. 2020) and electronic cigarettes (Effah et al. 2022; Holden and Hines 2016; Langel et al. 2022).