The gastrointestinal (GI) stability of three flavonoids, dihydromyricetin (DMY), myricetin (MYR), and myricitrin (MYT), was examined in simulated physiological fluids. Several factors that may influence the degradation rate of theses flavonoids were evaluated, including pH and the presence of pepsin and pancreatin enzymes. We found that GI stability followed the order of MYT > DMY > MYR. These flavonoids were stable in simulated gastric fluids and buffer solutions (pH 1.2), but encountered a pseudo-first-order kinetic degradation in simulated intestinal fluids and buffer solutions (pH 6.8). We conclude that it is the pH, rather than the presence of pepsin or pancreatin, which most strongly influences the stability of these three flavonoids. Further study of the stability of the compounds using a pH range (1.0–8.0) indicated potential instability in the duodenum, small intestine, and colon. Therefore, we conclude that the low bioavailability of these flavonoids may be due to their poor stability in the GI tract. Graphical Abstract

Stenosis of the critical blood vessels, which occurs in a variety of cardiovascular and cerebrovascular diseases, is one of leading causes of death in the world. Vascular stenosis will significantly alter the hemodynamic features in the vessel. Hemodynamic shear stress, one of the most important physical parameters of blood flow, will be dramatically elevated at the stenotic site. When platelets flow through the constricted site, they will sense these abnormally high shear stresses, and then respond by activating, sticking to the vascular wall, and aggregating at these sites. The shear-dependent platelet activation inspired a novel targeting platform-shear stress activated drug targeting delivery. The shear-activated drug delivery systems preferentially release their content under elevated shear stress, providing a novel approach to cure various diseases, in particular, cardiovascular diseases. In this review, we, on one hand, introduced the features of hemodynamic shear stress under both physiological and pathological conditions. On the other hand, we summarized the carriers displaying sensitivity to shear stress, such as liposomes, aggregations, gels, emulsions, in addition to the factors affecting the mechanical properties of them. Lastly, the clinical applications and prospects of this novel drug targeting strategy were discussed. It is hoped that, with a better understanding of shear stress-sensitive carriers and their targeted principle, a novel targeted drug delivery strategy will be one day applied in the clinics of the future.

In the present study, magnetic iron-zirconium co-oxide microspheres were successfully synthesized by the emulsion and coprecipitation method in a single step. To obtain the ultimate material that possesses high zirconia content and suitable magnetic response, the ratios of the reactants were investigated systematically. The corresponding microspheres were characterized by scanning electron microscopy (SEM), X-ray fluorescence (XRF), powder X-ray diffraction, (XRD), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption/desorption measurements. The magnetic property of the particles was studied by a magnetic balance. The results demonstrated that the optimum ratio of zirconium precursor (zirconyl chloride) to iron precursor (ferric trichloride) was 3.0:5.0 g, in which microspheres with diameter of 2–5 µm, high surface area up to 62 m²/g, and suitable magnetic property were obtained. The magnetic iron-zirconium co-oxide microspheres are promising in various applications, including catalysis, bioseparation, drug carrier, etc.