A Detailed Insight into the Effects of Morphologies of Cerium Oxide on Fenton-like Reactions for Different Applications.

As an exceptional Fenton-like reagent, cerium oxide (CeO2 ) finds applications in biomedical science and organic pollutants treatment. The Fenton-like reaction catalyzed by CeO2 typically encompasses two distinct processes: one resembling the classical Fenton reaction, wherein cerium (Ce3+ ) triggers the decomposition of hydrogen peroxide (H2 O2 ) to yield reactive oxygen species (ROS), and the other involves the complexation of H2 O2 on the Ce3+ surface, leading to the formation of peroxides. However, the influence of diverse CeO2 morphologies on these two reaction pathways has not been comprehensively explored. In this study, CeO2 exhibiting three typical morphologies, rods, cubes, and spheres, were prepared. The generation of ROS and peroxides was evaluated using the 3,3,5,5-tetramethylbenzidine (TMB) oxidation reaction and the reduction current of H2 O2 , respectively. Moreover, the impacts of pH variations and CeO2 /H2 O2 concentrations on the production and conversion of these two reaction products were investigated. To corroborate the distinctions between the resultant products and their applicability, apoptosis assays and acid orange 7 (AO7) degradation analyses were performed. Notably, CeO2 rods exhibited the highest proportion of Ce3+ , predominantly engaging in complexation with H2 O2 to foster peroxide formation, thereby facilitating the robust degradation of AO7. However, the generated peroxides appeared to occupy Ce3+ sites, thereby impeding the H2 O2 decomposition process. Conversely, Ce3+ species on the surface of CeO2 cubes were primarily involved in H2 O2 decomposition, leading to heightened ROS production, and thus showcasing substantial potential for damaging A549 tumor cells. It is worth noting that the ability of these Ce3+ species to form peroxides through complexation with H2 O2 was comparatively reduced. In summation, this study sheds light on the intricate interplay between distinct CeO2 morphologies and their divergent impacts on Fenton-like reactions. These findings expand our comprehension of the influences on its reactivity of CeO2 morphologies and open new insights for applications in diverse domains, from organic dye degradation to tumor therapy.

A Multifunctional Magnetic Red Blood Cell-Mimetic Micromotor for Drug Delivery and Image-Guided Therapy.

Inspired by nature, innovative devices have been made to imitate the morphology and functions of natural red blood cells (RBCs). Here, we report a red blood cell-mimetic micromotor (RBCM), which was fabricated based on a layer-by-layer assembly method and precisely controlled by an external rotating uniform magnetic field. The main framework of the RBCM was constructed by the natural protein zein and finally camouflaged with the RBC membrane. Functional cargos such as Fe3O4 nanoparticles and the chemotherapeutic agent doxorubicin were loaded within the wall part of the RBCM for tumor therapy. Due to the massive loading of Fe3O4 nanoparticles, the RBCM can be precisely navigated by an external rotating uniform magnetic field and be used as a magnetic resonance imaging contrast agent for tumor imaging. The RBCM has been proven to be biocompatible, biodegradable, magnetically manipulated, and imageable, which are key requisites to take micromotors from the chalkboard to clinics. We expect the RBC-inspired biohybrid device to achieve wide potential applications.

Slip-spring simulations of different constraint release environments for linear polymer chains.

The constraint release (CR) mechanism has important effects on polymer relaxation and the chains will show different relaxation behaviour in conditions of monodisperse, bidisperse and other topological environments. By comparing relaxation data of linear polyisoprene (PI) chains dissolved in very long matrix and monodisperse melts, Matsumiya et al. showed that CR mechanism accelerates both dielectric and viscoelastic relaxation (Matsumiya et al. 2013 Macromolecules 46, 6067. (doi:10.1021/ma400606n)). In this work, the experimental data reported by Matsumiya et al. are reproduced using the single slip-spring (SSp) model and the CR accelerating effects on both dielectric and viscoelastic relaxation are validated by simulations. This effect on viscoelastic relaxation is more pronounced. The coincidence for end-to-end relaxation and the viscoelastic relaxation has also been checked using probe version SSp model. A variant of SSp with each entanglement assigning a characteristic lifetime is also proposed to simulate various CR environment flexibly. Using this lifetime version SSp model, the correct relaxation function can be obtained with equal numbers of entanglement destructions by CR and reptation/contour length fluctuation (CLF) for monodisperse melts. Good agreement with published experiment data is also obtained for bidisperse melts, which validates the ability to correctly describe the CR environment of the lifetime version model.

Relation Between Superficial Calcifications and Plaque Rupture: An Optical Coherence Tomography Study.

BACKGROUND: There are several forms of calcium deposition, which play different roles in the stability of the coronary artery. It remains unknown whether certain calcification morphological characteristics determine rupture of lipid-rich lesions in the same plaque in acute coronary syndrome (ACS). METHODS: We retrospectively analyzed 550 patients with ACS between May 2008 and October 2014, who had undergone preintervention optical coherence tomography (OCT) imaging examination. A total of 78 patients with 78 culprit lipid-rich lesions having superficial calcifications on OCT images were included in this study, among which 45 were ruptured lesions with calcium and 33 were nonruptured lipid-rich lesion with calcium. The smallest depth of calcium (CAL-DEP) was determined, and the morphology of the calcifications and plaques was analyzed during preintervention OCT imaging. RESULTS: The CAL-DEP was significantly thinner in ruptured lesions with calcium than in nonruptured lipid-rich lesion with calcium (median, 50 [interquartile range (IQR), 33-63] µm vs 110 [73-208] µm; P < 0.001) and in myocardial infarction than in unstable angina pectoris patients (median, 57 [IQR, 36-78] µm vs median, 85 [IQR, 43-140] µm; P = 0.045). For lipid-rich calcified plaques, when CAL-DEP was < 63 µm, the lipid-rich lesion was most vulnerable and prone to rupture (sensitivity = 77.8%; specificity = 81.8%; area under the curve: 0.804; P < 0.0001). CONCLUSIONS: Small CAL-DEP in lipid-rich calcified plaques is a morphological characteristic of a vulnerable plaque phenotype. A CAL-DEP ≤ 63 µm is the critical depth of calcification for lipid-rich calcified plaque rupture in patients with ACS.