Afterglow materials have drawn considerable attention due to their attractive luminescent properties. However, their low‐efficiency luminescence in aqueous environment limits their applications in life sciences. Here, we developed a molecular fusion strategy to improve the afterglow efficiency of photochemical afterglow materials. By fusing a cache unit with an emitter, we obtained a blue afterglow system with a quantum yield up to 2.59 %. This is 162 times higher than that achieved with the traditional physical mixing system and more than an order of magnitude larger than that of the covalent coupling system. High‐efficiency afterglow nanoparticles were obtained and utilized for bio‐imaging with a high signal‐to‐noise ratio (SNR) of 131, and for the lateral flow immunoassay (LFIA) of β‐hCG with a low limit of detection (LOD) of 0.34 mIU mL−1. This paves a new way for the construction of high‐efficiency afterglow materials and expands the number of luminescence reporter candidates for disease diagnosis and bio‐imaging.
A well-dispersed self-assembled silver nanoparticles (AgNPs) ink with high purity was synthesized via AgNO
3
emulsion prepared by blending an AgNO
3
aqueous solution and a liquid paraffin solution of both polyoxyethylene (20) sorbitan monooleate (Tween 80) and sorbitan monooleate (Span 80). The ink remained as an emulsion at low temperatures; however, it produced AgNPs after sintering at about 60°C and showed a high stability at nanoscale sizes (with diameters ranging 8.6–13.4 nm) and a high conductivity. During the whole procedure, Tween 80 acted as a surfactant, reductant and stabilizer. Presumably, Tween 80 underwent an autoxidation process, where a free radical of an α-carbon of ether oxygen was formed by hydrogen abstraction. The mean diameter of emulsion droplets could be reduced by decreasing water content and increasing the ratio of surfactant and concentration of AgNO
3
aqueous solution. Consequently, the thermogravimetric analysis and X-ray diffraction result clarified the purity of the produced Ag
0
. Dynamic light scattering and ultraviolet-visible spectroscopy clarified that an increased concentration of AgNO
3
decreased the particle size.
Cellulose nanocrystals (CNCs) are extracted from cellulosic fibers via sulfuric acid hydrolysis and found to exhibit unique properties due to their nanoscale, ordered structure, and surface morphology.
Photochemical afterglow systems have drawn considerable attention in recent years due to their regulable photophysical properties and charming application potential. However, conventional photochemical afterglow suffered from its unrepeatability due to the consumption of energy cache units as afterglow photons are emitted. Here we report a novel strategy to realize repeatable photochemical afterglow (RPA) through the reversible storage of 1O2 by 2‐pyridones. Near‐infrared afterglow with a lifetime over 10 s is achieved, and its initial intensity shows no significant reduction over 50 excitation cycles. A detailed mechanism study was conducted and confirmed the RPA is realized through the singlet oxygen‐sensitized fluorescence emission. Furthermore, the generality of this strategy is demonstrated and tunable afterglow lifetimes and colors are achieved by rational design. The developed RPA is further applied for attacker‐misleading information encryption, presenting a repeatable‐readout.
Stimuli-responsive luminescent materials with timedependent color are highly desirable in optical information encryption. In this study, multiple time-dependent color processes are achieved by light-responsive afterglow materials through the strategy of absorption compensation. Based on the single-emission band of light-responsive afterglow materials, the color of samples could show a time-dependent change from colored to colorless over several seconds. The strategy possesses high flexibility such that the stimulus light and emission color of light-responsive afterglow materials can be adjusted conveniently to adapt to various scenes. It is also beneficial to expand the capacity and complexity of information encryption. A three-color, time-resolved anticounterfeiting, and data encryption mode is demonstrated. This facile absorption compensation method based on light-response afterglow materials may promote the development of advanced dynamic information encryption.
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