Guofen Zhou,Linlin Yu,Wenlong Guo,Zhongwei Jiang,Lianzhe Hu,Min Wang
In this study, nanozyme is used for monitoring the dose of ultraviolet (UV) in sunlight for the first time. We find that nitrogen-doped carbon dots (N-doped C-dots) can effectively catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) under different UV region including UVA, UVB, and UVC. In comparison, the N-doped C-dots fail to show the catalytic activity under visible light. The finding is applied for distinguishing UV light and visible light through the color change of TMB. More importantly, the photo-oxidation TMB catalyzed by N-doped C-dots can work well in a near neutral pH, which is beneficial for its application in wearable device due to the reducing of acid corrosion. Finally, a wearable bracelet is fabricated by integrating N-doped C-dots and TMB into hydrogels. The bracelet is used for monitoring the UV exposure in sunlight. The color change of TMB in the bracelet can be clearly observed by naked eyes or quantified by a smartphone. The bracelet is also used for distinguishing different weather condition such as sunny/cloudy or different place such as indoor/outdoor during a sunny day. This study provides the first example of nanozyme in wearable UV sensor and will stimulate the applications of nanozyme in wearable device.
In this study, we fabricate magnetic–fluorescent responsive Janus photonic crystal beads (JPCBs) based on poly(styrene-methyl methacrylate-acrylic acid) (p(St-MMA-AA)) colloidal nanoparticles, Fe3O4, and photobase generators used for self-destructive anti-counterfeiting. We synthesize two kinds of photobase generators that can react with fluorescamine to produce various fluorescence colors. A microfluidic method is used to obtain the Janus photonic crystal beads. The upper portions of the JPCBs are photonic crystals assembled with colloidal spheres, whereas the Fe3O4 settles down to the bottom of the JPCBs due to its higher density. Photobase generators are distributed in photonic crystal gaps. Because of the magnetism of the Fe3O4, the JPCBs could be flipped from one side to the other in the presence of a magnet. After being exposed to UVC light and fluorescamine, the JPCBs can fluoresce under UVA light. Then, we create Janus microbeads arrays with various types of beads and apply them to the visitor card, bracelet, and box label to provide irreversible and self-destructive anti-counterfeiting. The JPCBs are capable of being encoded and angle-independently displayed, which are crucial to their applications in anti-counterfeiting, information coding, and array display.
危险品化学品经营许可证（带存储）