Core-sheath nanofibers as drug delivery system for thermoresponsive controlled release

In this work, a smart drug delivery system of core–sheath nanofiber is reported. The core-sheath nanofibers were prepared with thermoresponsive poly-(N-isopropylacrylamide) (PNIPAAm) (as core) and hydrophobic ethylcellulose (EC) (as sheath) by coaxial electrospinning. Analogous medicated fibers were prepared by loading with a model drug ketoprofen (KET). The fibers were cylindrical without phase separation and have visible core-sheath structure as shown by scanning and transmission electron microscopy. X-ray diffraction patterns demonstrated the drug with the amorphous physical form was present in the fiber matrix. Fourier transform infrared spectroscopy analysis was conducted, finding that there were significant intermolecular interactions between KET and the polymers. Water contact angle measurements proved that the core-sheath fibers from hydrophobic transformed into hydrophobic when the temperature reached the lower critical solution temperature. In vitro drug-release study of nanofibers with KET displayed that the coaxial nanofibers were able to synergistically combine the characteristics of the two polymers producing a temperature-sensitive drug delivery system with sustained release properties. In addition, they were established to be non-toxic and suitable for cell growth. These findings show that the core–sheath nanofiber is a potential candidate for controlling drug delivery system

A seven‐year study on the effects of four tillage modes on soil physicochemical properties, microbial biomass, enzymatic activities, and grain yield in a rice–ratoon rice cropping system

Abstract Ratoon rice is resource efficient to produce economically sound and environmentally sustainable rice production. However, there is no more information on the relative impact of soil tillage practices on soil physical and chemical properties, microbial biomass, and enzymatic activity, and grain yield in a rice–ratoon rice cropping system remains to be tested. Systematic study of soil under ratooning rice model is a problem to be solved in the development of ratooning rice model. This study primarily investigated the long‐term (from 2014 to 2020) changes in soil bulk density (BD), soil organic carbon (SOC) concentration, total nitrogen (TN) concentration, microbial biomass, β‐glucosidase activity (BG), urease activity (UR), and yield under four treatments: no‐tillage (NT), no plowing tillage + rotatory tillage (RT), plowing tillage in winter + rotatory tillage (PTW), and plowing tillage in spring + rotatory tillage (PTS). NT increased BD by 9.65%–12.97%, and RT increased the 20–40 cm soil layer BD by 8.80% in 2020, compared with the baseline initial value (in 2014). Plowing tillage (PT) time had no significant effect on BD. All tillage methods decreased the SOC concentration in the 0–20 cm soil layer, and only RT increased the TN concentration. PT was the only treatment that increased the SOC and TN concentrations in the 20–40 cm soil layer. Both the main‐season rice yield and the ratoon season rice yield ranked PTW > PTS > NT > RT, in which the main‐season rice yield increased by 28.15% and the ratoon season rice yield increased by 25.19% in PTW. Overall, the PTW treatment had the highest microbial biomass, enzyme activity, and grain yield compared with the other tillage methods. In conclusion, plowing tillage in winter + rotatory tillage is a more suitable tillage method under the mode of ratooning rice