A facile approach for the reduction of 4‑nitrophenol and degradation of congo red using gold nanoparticles or laccase decorated hybrid inorganic nanoparticles/polymer-biomacromolecules vesicles

Abstract

Catalytic reduction of toxic 4‑nitrophenol to 4‑aminophenol and dye wastewater treatment over rapid, convenient gold nanoparticles or laccase decorated hybrid vesicles catalysts has attracted much attention. In current work, a stable building block was designed with inorganic gold nanoparticles and nano-conjugates; and a hybrid giant vesicles (AuNPs@vesicles) was self-assembled by using Pickering emulsion method. The vesicles were characterized by SEM, TEM, UV–vis and DLS measurements. The results showed that a temperature-responsive multifunctional building block based on BSA-PNIPAAm and gold nanoparticles was obtained. DLS results also indicated that the length of chains on the surface of AuNPs could change shorter with increasing of temperature (>32 °C) and also obtain an average diameter to ~190 nm. A substrate-rich (high concentration of 4‑nitrophenol) microenvironment can be created around AuNPs, which can dramatically accelerate the interfacial AuNPs-catalyzed reactions. The AuNPs@vesicles as catalyst in the presence of freshly prepared NaBH4 has excellent catalytic performance for reduction of 4‑nitrophenol (almost 100%). After laccase was capsulated into AuNPs@vesicles, the obtained active hybrid laccase⊂AuNPs@vesicles demonstrated high catalytic decolouration efficiency (>98.5%, nearly 2.3 times higher than that of free laccase) and excellent reusability. The possible mechanisms of reduction of 4‑nitrophenol and dye decolouration was proposed. These novel giant vesicles could provide some new opportunities in wastewater treatment, bottom-up synthetic biology, bioinspired microstorage/microreactor and drug/gene delivery.