BackgroundExtracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, can be secreted by most cell types and released in perhaps all biological fluids. EVs contain multiple proteins, specific lipids and several kinds of nucleic acids such as RNAs and DNAs. Studies have found that EVs contain double-stranded DNA and that genetic information has a certain degree of consistency with tumor DNA. Therefore, if genes that exist in exosomes are stable, we may be able to use EVs genetic testing as a new means to monitor gene mutation.MethodsIn this study, EVs were extracted from serum under various storage conditions (4 °C, room temperature and repeated freeze-thaw). We used western blotting to examine the stability of serum EVs. Then, we extracted DNA from EVs and tested the concentration changing under different conditions. We further assessed the stability of EVs DNA s using polymerase chain reaction (PCR) and Sanger sequencing.ResultsEVs is stable under the conditions of 4 °C (for 24 h, 72 h, 168 h), room temperature (for 6 h, 12 h, 24 h, 48 h) and repeated freeze-thaw (after one time, three times, five times). Also, serum DNA is mainly present in EVs, especially in exosomes, and that the content and function of DNA in EVs is stable whether in a changing environment or not. We showed that EVs DNA stayed stable for 1 week at 4 °C, 1 day at room temperature and after repeated freeze-thaw cycles (less than three times). However, DNA from serum EVs after 2 days at room temperature or after five repeated freeze-thaw cycles could be used for PCR and sequencing.ConclusionsSerum EVs and EVs DNA can remain stable under different environments, which is the premise that EVs could serve as a novel means for genetic tumor detection and potential biomarkers for cancer diagnostics and prognostics.

Utilizing the peritectic reaction and the miscibility gap featured in the pseudo-binary phase diagram of Mg2Si and Mg2Sn, we fabricated environmentally friendly Mg2(Si, Sn) thermoelectric (TE) composites in which the Mg2Si-rich bulk grains were in situ coated by Mg2Sn-rich thin layers. The Mg2Sn-rich grain boundary phase was selectively doped with La. It was found that the La doping dramatically increased the electrical conductivity to thermal conductivity ratio in the composites. As a result, a dimensionless figure of merit ZT ∼ 0.81 has been attained at 810 K for the Mg2−xLax(Si, Sn) in situ composite with x = 0.005, significantly higher than the ZT ∼0.18 at 540 K for the undoped composite and comparable to ZT ∼ 0.8 of state-of-the-art PbTe intermediate temperature TE alloys.

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In this work, a biodegradable poly(ethylene glycol)-poly(epsilon-caprolactone)-poly (ethylene glycol) (PEG-PCL-PEG, PECE) triblock copolymer was successfully synthesized, which was flowing sol at low temperature and turned to nonflowing gel at body temperature. The toxicity evaluation of PECE hydrogel as a potential in situ sustained opthalmic drug delivery system was performed, including the biodegradability of PECE hydrogel in the eye, its effect on cultured human lens epithelia, intraocular pressure, and ocular tissues. The results indicated that the prepared PECE hydrogel was biocompatible and biodegradable despite of temporary elevated intraocular pressure and slight corneal endothelial damage at specific concentration. Therefore, PECE hydrogel may be a safe candidate for sustained ophthalmic drug delivery system.

The thermal stability of the thermoelectric Zn 4 Sb 3 has been investigated by synchrotron power diffraction measurements in the temperature range of 300 K to 625 K in a capillary sealed under Ar. Data were also collected in air on a 1% Cd-doped sample. Rietveld refinements of the data indicate that a variety of impurity phases are formed. After heat treatment, more than 85% of the Zn 4 Sb 3 phase remains in the 1% Cd-doped sample heated in air, and 97% remains in the undoped Zn 4 Sb 3 heated in Ar. These stabilities are better than those previously observed in pure samples heated in air. This suggests that doping, as well as oxygen or oxidation impurities, play important roles in the thermal stability of this compound.