RESUMO
We report a simple "one-pot" solvothermal preparation of silver nanoparticles (Ag NPs) decorated mesoporous titania (TiO2) microspheres as an effective antibacterial agent. TBOT as Ti source was hydrolyzed and crystallized in media composed of acetic acid and ethanol, in which esterification catalyzed by TBOT occurred for in-situ "controlled water release". AgNO3 as Ag source was reduced by ethanol to form Ag NPs embedded in the TiO2 microspheres. The effect of AgNO3 and HAc on the morphology of Ag/TiO2 was investigated. The Ag/TiO2 with various Ag content showed excellent antibacterial activities with extremely low minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Escherichia coli and Staphylococcus aureus when compared with colloidal Ag NPs.
Assuntos
Antibacterianos/química , Nanopartículas Metálicas/química , Microesferas , Prata/química , Titânio/química , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Varredura , Porosidade , Nitrato de Prata/química , Staphylococcus aureus/efeitos dos fármacosRESUMO
Water-soluble 2'-O-hydroxypropyltrimethylammoniumchitin chloride (2'-O-HTACCt) was prepared directly from beta-chitin and 3-chloro-2-hydroxypropyltrimethylammonium chloride (CTA) in basic medium. The effect of alkali concentration, reaction temperature, reaction time, and dosage of CTA on yield and degree of substitution (DS) of 2'-O-HTACCt were studied. These quaternized chitin derivatives were characterized by FTIR and (1)H NMR spectroscopy, conductometric titration, and elemental analysis methods. Research results indicate that beta-chitin can react directly with CTA to produce a water-soluble 2'-O-HTACCt derivative with a high DS. The optimal preparation conditions were determined to be 35-40 wt% (aq NaOH), 40 degrees C (reaction temperature), 6h (reaction time), and 4 (molar ratio of CTA to beta-chitin unit).
Assuntos
Anti-Infecciosos/química , Anti-Infecciosos/síntese química , Quitina/química , Quitina/síntese química , Espectroscopia de Ressonância Magnética , Peso Molecular , Propanóis/química , Compostos de Amônio Quaternário/química , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Água/químicaRESUMO
OBJECTIVE: To remove harmful elements as copper, lead and arsenic from Polygonum multiflorum, a Chinese traditional medicine, by supercritical carbon dioxide extraction. METHODS: With sodium diethyldithiocarbamate (NaDDC) as a chelating agent and ethanol as a modifier, the effects of extraction style, time, pressure, temperature and amount of chelating agent on chelating extraction process were discussed. RESULTS: The condition was optimized as following: 28 MP as extraction pressure, 60 degrees C as extraction temperature, 1 h as static extraction time, 2 h as dynamic extraction time, m(herb) : m(NaDDC) = 5 : 1, m(herb) : m(ethanol) = 1 : 1. Under this condition, the extraction rate of Cu, Pb and As were up to 60% which achieved US FDA standard, while the physioloically active substance of 2,3,5,4'-tetrahydroxy-silbene-2-O-beta-D-glucoside was not extracted. CONCLUSION: The results show chelating extraction by supercritical CO2 can provide a non-destructive method to decrease the content of harmful elements from Chinese traditional medicines.
