The mechanism of writing with light depends on photoisomerization ability of light sensitive compounds. The recent advances in photoisomerization phenomenon of azobenzene derivatives are explained on the basis of experimental evidence. Azobenzene derivatives have few limitations in optical storage when it comes to practical and industrial purpose. However, azobenzene derivatives have significant interests because of their excellent light sensitivity and isomerization properties. The fabrication of azobenzene films also plays an important role in the production of an optical storage device. The molecular level layer properties, writing and erasing can be tuned by modification of molecular structures. To explain the concept, writing with light needs high light sensitivity and long duration of thermal back relaxation property. Hence, tuning of thermal back relaxation in the storage process is mainly considered.

In vivo biological imaging in first near-infrared window (NIR-I, 700-900 nm) and the second near-infrared window (NIR-II, 1000-1700 nm) using conjugated polymers have recently attracted great interest. Compared with imaging in visible region (400-700 nm), NIR bioimaging can provide deeper tissue penetration and higher spatial resolution due to fewer scattering of longer-wavelength photons. Moreover, most of NIR-I and NIR-II conjugated copolymers have been reported with tunable excitation and emission of fluorophores through modification of their donor-acceptor structures. In this minireview, we focus on the recent advances on chemical synthesis of conjugated polymers and their biological imaging in NIR-I and NIR-II windows.

Magnetic nanoparticles (MNPs) possess great potential in biological applications, especially as a highly useful tool or contrast agents for clinical diagnosis and disease monitoring in magnetic resonance imaging. When external magnetic field is introduced, the local magnetic field inhomogeneity caused by magnetization of MNPs can induce the change of relaxation for realizing the imaging. Therefore, rational design of magnetic relaxation switches sensors capable of biological detection has been a major goal in the advancement of clinical application. In this minireview, we summarize some advances on magnetic sensors, involving in sensing principles of MNPs and biological applications of magnetic sensors; moreover, we collect important and up-to-date information, which may help to develop the method of obtaining high performance magnetic sensors, especially for biological application.

Transition metal oxides with nanoscale or special micro-structures are favoured both in scientific research and industry application. Although many methods are developed, there is still a need and a potential payoff for developing a novel and convenient synthetic method. Inspired by nature hydrothermal vent, herein, we develop an ingenious “top-down” method to prepare various transition material compounds, which have diverse and fascinating structures. Our design thought is to etch the A ions by acid from the precursor A_xM_yO_z (A=alkaline and alkaline earth metal, M=transition metal) and leave the MO_n/2 or HMO_(n+1)/2 behind under the hydrothermal condition. As a result, we obtain various structures like amorphous mesoporous bulk Nb₂O₅, morphology-re- tained bulk HNbO₃ and ZrO₂, monodispersed ZrO₂ nanoparticles, assembled porous ZrO₂ nanostructure, hollow TiO₂, and the derived core-shell structure. These materials have great potential application in catalysis and energy storage. We employed hollow TiO₂ cube as the high cut-off anode of lithium-ion batteries and harvested excellent performance. After these fruitful attempts, we have found that etching A_xM_yO_z to obtain transition metal compound is a complex reaction containing some different competing reactions, thus allowing us to regulate and control the microstructure of the products by adjusting the reaction condition. We believe there are more interesting structures waiting to be fabricated by similar “top-down” method and these unique materials have great potential in many fields.

A polysaccharide hydrogel is prepared by mixing hydroxyethylcellulose (HEC), ibuprofen (IBU) and ethylenediamine-β-cyclodextrin (EDA-CD) in water with special sequence at certain concentration. The biocompatible polymer of HEC is used as the hydrogel matrix. IBU is a poorly water-soluble drug, which is widely applied to the clinical. EDA-CD with dual-role is used as cross-linker and hydrophobic drug carrier. FTIR, ¹H NMR and ¹³C NMR were used to characterize EDA-CD. Hildebrand-Benesi equation and phase solubility method were used to investigate the binding mode of EDA-CD and IBU. The binding constant of EDA-CD and IBU is 4055 L·mol^-1, the stoichiometry ratio is 1:1, and the water solubility of IBU in EDA-CD solution can reach 5 g in 100 mL of water. SEM was used to observe the surface morphology of the dry hydrogel. A porous surface analysis of the dry hydrogel has revealed that the molecule weight and the amount of the HEC polymer affect obviously the gelation process. UV spectrophotometer was used to detect the content of IBU in the hydrogel. The in vitro release test of IBU in hydrogel was investigated and some suitable kinetic models are used for explaining the releasing mechanism.