No abstract

It is of extreme importance to reduce side effects resulting from the nonspecific uptake of phototherapeutic agents by normal tissues. Currently, the single responsive strategy still cannot entirely satisfy the requirements of practical applications. In this study, we developed one kind of combination-responsive phototherapeutic nanoplatforms, where oxygen-deficient molybdenum oxide (MoO 3−x ) hybridized hyaluronic acid (HA) hollow nanospheres, namely, MoO 3−x @ HA HNSs, were constructed via a facile one-step method. In MoO 3−x @HA HNSs, the reasonable combination of actively targeted specificity endowed by the HA component and tumor microenvironment-responsive phototherapy activity induced by the MoO 3−x component can effectively improve the precision of phototherapy. The in vitro and in vivo experimental results confirm that MoO 3−x @HA HNSs can selectively kill CD44-overexpressing cancer cells and inhibit tumor growth under an 808 nm laser irradiation, revealing their remarkable synergistic photothermal therapy/ photodynamic therapy effect with CD44 receptor-targeted specificity and pH responsiveness in treating cancer. We also prove that MoO 3−x @HA HNSs can serve as one kind of contrast agent to achieve the computed tomography/photoacoustic imaging. Encouraged by these results, it is anticipated that the reasonable combination of active targeting and tumor microenvironment responsiveness can be a promising strategy to develop phototherapeutic nanoplatforms for precise multimodality cancer theranostics.

The presence of thin aqueous films and their stability have a profound effect on the interactions between oil/brine/rock interfaces. In a previous report, we proposed that hydration forces, originating from the overlap of hydrated layers of different surfaces in the presence of sodium chloride, played an important role at short range. In the present work, divalent ions were introduced to the liquid films and, the mechanisms in improving oil recovery from low-salinity brine and the low-salinity effect at the molecular level were revealed. Through a direct force-measuring technique of chemical force microscopy (CFM), the functionalized atomic force microscopy (AFM) tips felt a solid surface to mimic the oil/rock interactions in brine. It was found that not only did the van der Waals and electrostatic forces have a great effect on this process due to the interactions between the charged interfaces of oil/water and water/solid, but also some important additional interactions appeared at short range under a variety of salinity concentrations or compositions. Taking into account the important role of structural forces under a small distance, the force profiles were fitted well with the theory of extended Derjaguin–Landau–Verwey–Overbeek (denoted by EDLVO) through a double-exponential or Gaussian model. Interestingly, low adhesion appeared in the presence of sodium sulfate, because hydration forces contributed to the resultant force depending on the intrinsic properties of the solvent or solute molecules, while in the presence of calcium chloride, high adhesion emerged due to the dispersion interaction between water and hydrocarbon molecules, as well as the reorientation or restructuring of water molecules with tiny breakage of hydrogen bonds. Therefore, on the basis of the EDLVO theory, additional forces were suggested to play an important part in short range, proposing a better understanding of the effect of divalent ions on the thin liquid films in the process of increasing oil recovery.

Catalytic cracking of n-decane was performed over monometallic and bimetallic Pt–Ni catalyst supported La–Al2O3 modified by MoO3 (MLA), aiming to investigate the effects of acidity, active phase dispersion, and synergistic effect between Pt and Ni on catalytic performance of the catalysts. The catalysts were characterized by the techniques of Brunauer–Emmett–Teller (BET), hydrogen temperature-programmed reduction (H2-TPR), X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH3-TPD), X-ray photoelectron spectroscopy (XPS), CO chemisorption, and transmission electron microscopy/energy-dispersive spectroscopy (TEM/EDS) mapping. The results showed that catalytic cracking activities over catalysts were heightened compared with MLA, especially bimetallic catalyst. Meanwhile, bimetallic catalyst exhibited the best high-temperature stability. Otherwise, cracking activity over regenerative bimetallic catalyst nearly approached that of the fresh one. The most effective findings of properties of bimetallic catalyst presented as follows: the unique acidity, higher resistance against sintering of active phases, and finely dispersed actives due to enhanced metal–support interaction and synergistic effect between Pt and Ni can be responsible for its stable catalytic activity and thermal stability, and capable regeneration.