Liu Ye,Xuyang Liu,Yingbo Chen,Linzhe Xu,Shuang Fu,Xintong Wu
In this study, a hollow fiber nanofiltration membrane with excellent salt tolerance and anti-fouling properties was successfully prepared by Fe 3+ /tannic acid (TA) assisted dynamic assembly technology. The results showed that when the concentration of Fe 3+ and TA was 0.1 g·L -1 , the rejection rate of Na 2 SO 4 was 91.34%, and the permeability was 12.44 L·m -2 ·h -1 ·bar -1 . The salt tolerance test showed that the rejection rate did not change significantly in the range of 1-5 g·L -1 Na 2 SO 4 concentration. The rejection rate of the membrane to 5 g·L -1 Na 2 SO 4 solution was 85.22%, thanking to the strong binding force between the Fe 3+ -TA coordination bonds. The high hydrophilicity of the coating layer and the dense structure of the Fe 3+ -TA coordination network significantly reduced the irreversible adsorption of pollutants, which provided the membrane with stable permeability after three times of fouling-cleaning cycles with bovine serum albumin (BSA) and humic acid (HA) as model pollutants. The dense network structure formed by dynamic assembly assisted with Fe 3+ -TA coordination was the key to the high rejection and salt tolerance of the membrane, which provided a new strategy for the development of high-performance nanofiltration membranes for high-salt wastewater treatment in practical applications.
Light-driven hydrogel actuators show potential applications because their spatiotemporal precision and contact-free manner, especially for near-infrared light (NIR), can be focused on a specific area, which possesses tunable intensity and strong penetrability. Herein, we propose a novel NIR-responsive hydrogel actuator incorporating Fe3+/tannic acid (Fe3+/TA) as a photothermal transducer into the poly(N-isopropylacrylamide) (PNIPAAm) hydrogel via photo-cross-linking and subsequent immersion in FeCl3 solution. TA contains abundant pyrogallol and catechol groups, which can be linked to PNIPAAm through hydrogen bonds during in situ polymerization; moreover, as a mediator, TA can form metal-phenolic networks with Fe3+ via the coordination between catechol and metal ions, endowing the PNIPAAm gel with enhanced mechanical properties as well as NIR-responsive photothermal effect. We demonstrated that introduction of Fe3+/TA maintained the volume phase transition temperature of the hydrogel around 32 °C and guaranteed its deformation behaviors upon NIR irradiation. Furthermore, a higher concentration level of BIS and Fe3+ were verified to facilitate a stronger photothermal capacity of the hydrogels. Therefore, under NIR irradiation, Fe3+/TA within the hydrogel converted NIR light into heat, and the local high temperature in the irradiated region would cause the petals of the “snowflake”-shaped hydrogel to bend upward perpendicular to the horizontal plane within 1 min, possessing excellent repeatability. This study puts forward a new idea of preparing NIR-responsive hydrogel actuators based on Fe3+/TA, which show promising application in the fields of biomimetic devices, flowing control, and soft robotics.
Although chemodynamic therapy (CDT) holds the advantage of tumor treatment by generating hydroxyl radicals (·OH) without the participation of O 2 , insufficient H 2 O 2 and the hindered Fe ion circulation remain major hurdles for its clinical application. Herein, we developed a hybrid nanoparticle with H 2 O 2 self-supply and iron ion self-circulation properties for enhanced CDT. Through encapsulation of CaO 2 with ZIF-8 and in situ assembled Fe 3+ /TA (tannic acid) on the surface, the hybrid nanoparticles (CaO 2 @ [email protected] ) were prepared. The Fe 3+ /TA coating could dissociate in response to lysosomal acidity, and release Fe 3+ and TA subsequently. Significantly, the unprotected CaO 2 can be degraded to H 2 O 2 and Ca 2+ , providing sufficient materials for CDT and resulting in a Ca 2+ “storm” for ion therapy. Meanwhile, TA could convert Fe 3+ to Fe 2+ , realizing a self-circulation for promoting the sustained generation of ·OH. Interestingly, Fe 3+ /TA coating endows the nanoparticles with photothermal property, which accelerated the degradation and further improved the efficiency of Fenton reaction, obtaining 77.7% of tumor growth inhibited rate without obvious adverse effect in tumor-bearing mice. Our findings showed CaO 2 @ [email protected] had potential to be applied for enhanced CDT synergistic antitumor ion therapy.
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