Soft fluorescent nanomaterials have attracted recent attention as imaging agents for biological applications, because they provide the advantages of good biocompatibility, high brightness, and easy ...biofunctionalization. Here, we provide a survey of recent developments in fluorescent soft nano-sized biological imaging agents. Various soft fluorescent nanoparticles (NPs) (including dye-doped polymer NPs, semiconducting polymer NPs, small-molecule organic NPs, nanogels, micelles, vesicles, and biomaterial-based NPs) are summarized from the perspectives of preparation methods, structure, optical properties, and surface functionalization. Based on both optical and functional properties of the nano-sized imaging agents, their applications are then reviewed in terms of in vitro imaging, in vivo imaging, and cellular-process imaging, by means of specific or nonspecific targeting.
Recently, a great deal of interest has been developed to isolate and investigate novel bioactive components with health benefit effects from natural resources. The dried root of Astragalus ...membranaceus, one of the most popular health-promoting herbal medicines, has been used historically as an immunomodulating agent for the treatment of common cold, diarrhea, fatigue and anorexia for more than 2000 years. Modern phytochemistry and pharmacological experiments have proved that polysaccharide is one of the major active ingredients in the root of A. membranaceus with various important bioactivities, such as immunomodulation, antioxidant, antitumor, anti-diabetes, antiviral, hepatoprotection, anti-inflammation, anti-atherosclerosis, hematopoiesis and neuroprotection. The aim of the present review is to summarize previous and current references and give a comprehensive summary regarding the structural features and biological activities of A. membranaceus polysaccharides in order to provide new insight for further development of these macromolecules.
Ab initio calculations based on density functional theory are performed to study the stability of newly proposed C3N4 forms. Heptazine-based g-C3N4 was found to be energetically favored relative to ...other phases. The quasiparticle band energies of different C3N4 phases are calculated using the GW method. Among the seven phases of C3N4 studied, only the pseudocubic phase and g-h-triazine phase have direct band gaps, and all of the other phases have indirect band gaps. The band gap of α-C3N4, β-C3N4, cubic-C3N4, pseudocubic-C3N4, g-h-triazine, g-o-triazine and g-h-heptazine is 5.49 eV, 4.85 eV, 4.30 eV, 4.13 eV, 2.97 eV, 0.93 eV and 2.88 eV, respectively. From the viewpoint of band gap energies, both the g-h-heptazine and the g-h-triazine phases can be used as suitable photocatalysts for hydrogen production using water.
► Band gap characters of seven C3N4 polymorphs investigated by GW method. ► g-h-triazine phase of graphitic C3N4 has a direct band gap of 2.97 eV. ► g-h-heptazine phase of graphitic C3N4 has an indirect band gap of 2.88 eV. ► g-o-triazine phase of graphitic C3N4 has an indirect band gap of 0.93 eV.
Recently, isolation and investigation of novel ingredients with biological activities and health benefit effects from natural resources have attracted a great deal of attention. The fruit of Lycium ...barbarum L., a well-known Chinese herbal medicine as well as valuable nourishing tonic, has been used historically as antipyretic, anti-inflammation and anti-senile agent for thousands of years. Modern pharmacological experiments have proved that polysaccharide is one of the major ingredients responsible for those biological activities in L. barbarum. It has been demonstrated that L. barbarum polysaccharides had various important biological activities, such as antioxidant, immunomodulation, antitumor, neuroprotection, radioprotection, anti-diabetes, hepatoprotection, anti-osteoporosis and antifatigue. The purpose of the present review is to summarize previous and current references regarding biological activities as well as potential health benefits of L. barbarum polysaccharides.
Geometry optimizations are performed for three polytypes of h-BN using density functional theory with dispersion correction for the van der Walls interaction. Quasiparticle band structure ...calculations are carried out to solve the controversy on band gap type of h-BN. Band energies are corrected by GW method. The h-BN with Bk structure has an indirect band gap of 5.840eV. Two kinds of h-BN polytypes are shown to be mechanically stable and have quasi-direct band gap type.
► Structures of hexagonal boron nitride polytypes are studied by dispersion-corrected DFT. ► Band gap characters of hexagonal boron nitride are predicted by GW method. ► Hexagonal boron nitride polytype with quasi-direct band gap type is probably exists. ► GW band-gap energies are used to interpret recently reported experimental results.
The understanding of the structural stability and properties of dielectric materials at the ultrathin level is becoming increasingly important as the size of microelectronic devices decreases. The ...structures and properties of ultrathin ZrO2 (monolayer and bilayer) have been investigated by ab initio calculations. The calculation of enthalpies of formation and phonon dispersion demonstrates the stability of both monolayer and bilayer ZrO2 adopting a honeycomb-like structure similar to 1T-MoS2. Moreover, the 1T-ZrO2 monolayer or bilayer may be fabricated by the cleavage from the (111) facet of non-layered cubic ZrO2. Moreover, the contraction of in-plane lattice constants in monolayer and bilayer ZrO2 as compared to the corresponding slab in cubic ZrO2 is consistent with the reported experimental observation. The electronic band gaps calculated from the GW method show that both the monolayer and bilayer ZrO2 have large band gaps, reaching 7.51 and 6.82 eV, respectively, which are larger than those of all the bulk phases of ZrO2. The static dielectric constants of both monolayer ZrO2 (ϵ‖ = 33.34, ϵ⊥ = 5.58) and bilayer ZrO2 (ϵ‖ = 33.86, ϵ⊥ = 8.93) are larger than those of monolayer h-BN (ϵ‖ = 6.82, ϵ⊥ = 3.29) and a strong correlation between the out-of-plane dielectric constant and the layer thickness in ultrathin ZrO2 can be observed. Hence, 1T-ZrO2 is a promising candidate in 2D FETs and heterojunctions due to the high dielectric constant, good thermodynamic stability, and large band gap for applications. The interfacial properties and band edge offset of the ZrO2–MoS2 heterojunction are investigated herein, and we show that the electronic states near the VBM and CBM are dominated by the contributions from monolayer MoS2, and the interface with monolayer ZrO2 will significantly decrease the band gap of the monolayer MoS2.
Glutathione is the principal intracellular antioxidant buffer against oxidative stress and mainly exists in the forms of reduced glutathione (GSH) and oxidized glutathione (GSSG). The processes of ...glutathione synthesis, transport, utilization, and metabolism are tightly controlled to maintain intracellular glutathione homeostasis and redox balance. As for cancer cells, they exhibit a greater ROS level than normal cells in order to meet the enhanced metabolism and vicious proliferation; meanwhile, they also have to develop an increased antioxidant defense system to cope with the higher oxidant state. Growing numbers of studies have implicated that altering the glutathione antioxidant system is associated with multiple forms of programmed cell death in cancer cells. In this review, we firstly focus on glutathione homeostasis from the perspectives of glutathione synthesis, distribution, transportation, and metabolism. Then, we discuss the function of glutathione in the antioxidant process. Afterwards, we also summarize the recent advance in the understanding of the mechanism by which glutathione plays a key role in multiple forms of programmed cell death, including apoptosis, necroptosis, ferroptosis, and autophagy. Finally, we highlight the glutathione-targeting therapeutic approaches toward cancers. A comprehensive review on the glutathione homeostasis and the role of glutathione depletion in programmed cell death provide insight into the redox-based research concerning cancer therapeutics.
PDF
