In this study, the distribution characteristics of nano-TiO 2 aerosol have been studied to get insight of the suspension, agglomeration and depositing performances of aerosol nanoparticles in the workplace. The number concentration and mass concentration of the aerosols have been characterized by using a wide-range particle spectrometer and cascade impactor samplers, respectively. Water based wet aerosol samplers, as well as its corresponding analysis approaches based on ultraviolet spectrometry, have also been developed to investigate the mass concentration and present an efficient sampling performance with the quite shorter sampling time than that by cascade impactors. To get a comparison of the test results with each other, sampling points have been set at the heights of breathing zone (1.0, 1.5 and 2.0 m) and at the distances of 1 to 5 m away from the discharge port of the assembly line. It is found that all the number concentration curves exhibit two peaks at the ranges of 10-200 nm and 500-900 nm. The aerosol particles with distance of 3 m exhibit the highest number concentration at all the diameter range except for the diameter less than 20 nm. While, aerosol at the distance of 5 m presents the highest number concentration, up to 18000 particles per cm 3 , in the diameter less than 20 nm. It is attributed to the spray forces of the discharge port and the suspending and depositing of aerosol nanoparticles in the air. The mass concentration and particle weight percentage at different diameter tested by cascade impactor show a strong dependence on the number concentration, which is well consistent with the results obtained by wet method.
Polymers with targeted ligands are widely used as the anti-cancer drug delivery materials. For applications of chitosan as an anti-liver cancer drug delivery, poly (ethylene glycol)/lactobionic acid-grafted chitosan (PEG/LA-CS) was prepared and investigated since lactobionic acid can be specifically recognized by the hepatocytes. The structure of the PEG/LA-CS was characterized by Fourier transform infrared spectrometry and elemental analysis. The self-assembly behaviors of the PEG/LA-CS were monitored by steady-state fluorescence spectroscopy and electronic transmission microscope. The protein adsorption of the PEG/LA-CS was detected with bovine serum albumin (BSA) by electrochemical impedance spectroscopy. The results showed that the PEG/LA-CS almost did not adsorb protein. To study the effects of PEG/LA-CS on the structure of BSA, the interactions between the PEG/LA-CS and BSA were detected by ultraviolet spectrum, fluorescence spectrum, and circular dichroism. All the data gave one result that BSA maintained its original folded confirmation in PEG/LA-CS solution. The hemocompatibility of PEG/LA-CS was investigated by observing the effects of PEG/LA-CS on the hemolysis rate and the plasma recalcification time (PRT). The results showed that the PRT was prolonged greatly and the hemolysis rate was less than 5%. Furthermore, PEG/LA-CS also showed good cytocompatibility with K562, Hep G2, and LO2 cells. Therefore, the PEG/LA-CS is believed to have great potential for producing injectable anti-liver cancer drug delivery.
Aromatic azo derivatives possess a particular character that is the light driven reversible isomerization between their cis-and trans-forms, which makes them excellent candidates to modulate the relative movement of different moieties. They are widely used not only in the traditional chemical industry, but also in many newly rising areas of science, such as photochemical molecular switch, super-molecular chemistry of host-guest recognition, self-assembly liquid crystal material, analysis of biomedical imaging and chemical, light driven molecular motor, and so on. The development of chromophores with characteristics, like high chemical stability, thermal stability over a wide temperature range and having two forms easily detectable by a method that does not cause irreversible molecular alterations, is a major challenge for researchers who focus their interest in this area. With the increasing need for investigating unknown aromatic azo derivatives, many novel efficient synthesis strategies are recently innovated and developed in succession. This critical review covers the various synthetic methods of aromatic azo derivatives reported more recently, with special emphasis on application of arylhydrazine, arylamine, nitroarene, azoxyarene, arylazide, and their derivatives.
This study is to prepare a nanosuspension based on poly(lactic‐co‐glycolic acid) (PLGA) for delivery, controlled release and enhanced anti‐solid tumor effects of As2O3. As2O3‐loaded PLGA nanocapsules (As2O3‐PLGA NCs) were prepared by double emulsion‐solvent evaporation method and were optimized by univariate analysis in combination with orthogonal experimental according to several factors. The optimized As2O3‐PLGA NCs presented suitable physical stability, favorable size of (200.2±10.6) nm (PDI=0.117±0.008), spherical shape, and high encapsulation efficiency (92.48%±2.14%). The in vitro suspension stability of the NCs was excellent. The release of As2O3 from the NCs showed pH responsive release characteristics. The NCs can be efficiently taken up by SMMC‐7721 cell and showed excellent antitumor efficacy against SMMC‐7721 cell line. Then, As2O3‐PLGA NCs could be considered as a promising formulation for the pH dependent release of As2O3 in cancer cells and enhance the anti‐solid tumor effects of As2O3.
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