Репозиторий Университета

© 2020 Microcapsules are ideal cargo platform for variety of applications such as drug delivery, sensing and imaging due to the combination of a simplicity fabrication and flexibility in the design. We developed remotely collapsing polymer capsules to response to external microwave treatment. The multilayer structure of the capsules was designed to create a polyfunctional system intercalating with nanodiamonds (NDs) and upconversion nanoparticles (UCNPs) into the polyelectrolyte shell. NDs empower local overheating to the microcapsules, while UCNPs provide opportunity to luminescent thermal sensing. UCNPs consist of inorganic crystalline host matrix - hexagonal β-phase NaYF4, doped with pairs of trivalent lanthanide ions, which play role of sensitizer (Yb3+) and activator (Er3+). The microwave triggering followed by the capsule heating results in the controlled destruction of the polyelectrolyte shell with subsequent cargo release. UCNPs luminescence was utilized to determine the local temperature of the capsule shell at nanoscale under GHz ultrasonic treatment. Our novel approach provides on demand microcapsule system destruction, which can be used in the development of nanotheranostic platform for the unification of diagnosis and treatment of various diseases.

© 2020 Elsevier B.V. The development of a highly efficient and rapid method for the accurate preparation of photocatalysts with novel morphologies is a hot research topic. The different morphologies of BiVO4 was prepared using surfactants-assisted microwave method, and demonstrated irregular (no surfactant), octahedral (sodium dodecyl benzene sulfonate), olive-like (polyvinylpyrrolidone) and hollow structures (ethylenediaminetetraacetic acid), respectively. The BiVO4-CdS were synthesized using the chemical-bath-deposition method with different morphologies of BiVO4 as the substrates. The hollow structure of BiVO4 displayed the highest photocatalytic performance. Moreover, the photodegradation rates of the hollow structure BiVO4-CdS on tetracycline hydrochloride and ciprofloxacin were about 1.8 and 1.5 times higher than the corresponding BiVO4, indicating that the Z-scheme heterojunction can improve the photogenerated electron pairs separation efficiency. Furthermore, the regulation mechanism of morphology and energy-band position, as produced using the surfactants, has also been thoroughly investigated in this work, which provides a novel insight into the efficient and rapid preparation of photocatalysts with special morphology and high performance.

© 2019 Nanodiamonds (ND) are one of the most attractive carbon materials for nanotechnology. The impregnation of NDs into the polymer capsule shell in the form of the single nanoparticles insures the control over the thermal conductivity of the capsule shell and increases their sensitivity to the external microwave irradiation. The polymer shell of the polyelectrolyte capsules was modified with NDs by electrostatic adsorption technique. The sensitivity of the capsules with embedded NDs to the external microwave irradiation was demonstrated by scanning electron microscopy leading to the shell rupture and release of the encapsulated agents.

© 2019 Institution of Chemical Engineers Enabling technologies have led to the design of new extraction protocols for naturally occurring compounds that are fast, sustainable and have low energy demands. Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) have been used, in this study, for the recovery of valuable nutraceuticals and primary metabolites from pumpkin seeds (Curcubita sp.) and have been compared with conventional methods. In order to optimise extraction parameters and conditions, we have compared yields, total phenolic content, antioxidant activity, as well as fatty-acid and lipid profiles. The best yield, in both lipophilic and hydrophilic compounds, was achieved under UAE with a ternary solvent mixture (hexane/ethanol/water - 30:49:21). However, the highest phenolic content and antioxidant capacity were obtained using MAE under subcritical conditions with good extraction yields. The oil composition, as obtained using GC-FID analyses, showed a prevalence for unsaturated fatty acids; mainly linoleic and oleic acids. The use of UAE with ternary mixtures presented the highest lipid content and a slightly higher percentage of unsaturated compounds. Preliminary tests to verify the scalability of UAE with a ternary mixture showed that the extraction performance was maintained when using larger volumes (factor 10). This study will pave the road for the potential exploitation of UAE as a fast and efficient procedure for the simultaneous recovery of lipophilic and hydrophilic compounds from pumpkin seeds.