A new kind of photoswitchable polymer nanoparticle is prepared using polymerizable alkenyl carbon dots (PCDs) and a spiropyran derivative, together with methyl methacrylate (MMA) as the monomer, and mediated by one-pot miniemulsion polymerization. Switching between two different wavelengths of emitted light can be realized by intraparticle fluorescence resonance energy transfer (FRET). The FRET efficiency could be easily controlled by the feed ratios of the two chromophores and the excitation wavelengths. UV and visible light can be applied to modulate the fluorescence emission of the prepared nanoparticles. Upon visible light irradiation, the nanoparticles emit blue-green fluorescence of the CDs while spiropyran is in its closed form (SP). UV irradiation of SP gives rise to an open-ring isomer (MC). An SP-to-MC photoisomerization triggers a CD-to-MC FRET, and the resulting nanoparticles emit red light. Their fluorescence could be reversibly switched between blue-green and red by using UV/vis light irradiation with excellent photoreversibility and high stability. In addition, the novel nanoparticles with reversibly photoswitchable fluorescence could be directly applied in rewritable fluorescence patterning and dual-color fluorescence imaging of living cells.

中文翻译：

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基于具有光可逆双色荧光调制的CD的聚合物纳米颗粒

利用可聚合的烯基碳点（PCD）和螺吡喃衍生物，以及甲基丙烯酸甲酯（MMA）作为单体，制备了一种新型的光开关聚合物纳米粒子，并通过一锅法细乳液聚合反应进行了介导。可以通过粒子内荧光共振能量转移（FRET）实现在两个不同波长的发射光之间切换。通过两个生色团的进料比和激发波长可以轻松控制FRET效率。可以施加紫外线和可见光来调节制备的纳米颗粒的荧光发射。在可见光照射下，当螺吡喃为封闭形式（SP）时，纳米粒子会发出CD的蓝绿色荧光。SP的紫外线照射会产生开环异构体（MC）。SP到MC的光异构化触发CD到MC的FRET，并且所得的纳米粒子发出红光。通过使用具有优异的光可逆性和高稳定性的UV / vis光照射，可以将它们的荧光可逆地在蓝绿色和红色之间切换。此外，具有可逆光开关荧光的新型纳米颗粒可直接用于活细胞的可重写荧光图案和双色荧光成像。