Regulation of drug release performance using mixed doxorubicin-doxorubicin dimer nanoparticles as a pH-triggered drug self-delivery system

A mixed drug self-delivery system(DSDS)with high drug content(>50%)was developed to regulate pHtriggered drug release,based on two doxorubicin(DOX)-DOX dimmers:D-DOX_(ADH) and D-DOX_(car) conjugated with acid-labile dynamic covalent bonds(hydrazone and carbamate,respectively)and stabilized with PEGylated D-DOX_(ADH)(D-DOX_(ADH)-PEG).Owing to the different stability of the dynamic covalent bonds in the two dimers and the noncovalent interaction between them,pH-triggered drug release could be easily regulated by adjusting the feeding ratios of the two DOX-DOX dimers in the mixed DSDS.Similar in vitro cellular toxicity was achieved with the mixed DSDS nanoparticles prepared with different feeding ratios.The mixed DSDS nanoparticles had a similar DOX content and diameter but different drug releasing rates.The MTT assays revealed that a high anti-tumor efficacy could be achieved with the slowrelease mixed DSDS nanoparticles.

First standard released to regulate the study and use of stem cells

China’s first general standard for stem cells officially released on November 22,2017 is expected to lay a foundation for regulating the application of stem cells technology.Stem cells are a group of self-renewal cells that can differentiate into specialized cells.They are now used for the treatment of many diseases.Despite a series of documents for regulating basic research and achievement transformation of stem cells,

Chemical characterization, release, and bioactivity of Eucalyptus camaldulensis polyphenols from freeze-dried sodium alginate and sodium carboxymethyl cellulose matrix

Crude ethanolic extract of Eucalyptus camaldulensis was encapsulated with sodium alginate- sodium carboxymethyl cellulose (CMC) using freeze-drying techniques. The microcapsules were characterized for particle size, morphology, physicochemical parameters, and micromeritics properties. Antioxidant and antimicrobial activities of the microcapsules were also demonstrated. Results revealed an irregular-shaped microparticles with a mean diameter ranging from 6.7 to 26.6 μm. Zeta potential and polydispersity index ranged from −17.01 to 2.23 mV and 0.34 to 0.49, respectively. Percentage yield ranged between 70.4 and 81.5 per cent whereas encapsulation efficiency ranged between 74.2 ± 0.011 and 82.43 ± 0.77 per cent. Swelling index and solubility varied inversely with extract concentration, with a range of 54.4%-84.0% and 18.8%-22.2%, respectively. Antioxidant activities varied directly with the concentration of the extract. Minimum inhibitory and minimum bactericidal concentrations of the microcapsules against Gram-positive foodborne pathogens ranged from 0.19 to 3.12 and 0.19-12.25 mg/ml, respectively. The Higuchi model indicated a time-dependent, delayed, and regulated release of polyphenols at 37°C. The results suggested that alginate-CMC possessed good encapsulant properties that preserved the bioactive extract, thus might be employed for application of natural products in food systems.