Recent years have seen molybdenum oxide quantum dots (MoO_x QDs) as a booming material due to their attractive physical and chemical properties. However, there is still a large demand for MoO_x QDs with long-wavelength emission by a facile strategy but these are more challenging to obtain. Herein, we rationally designed and successfully prepared nitrogen and phosphorus co-doped green emitting MoO_x QDs (N,P-MoO_x QDs) through a microwave-assisted rapid method. They exhibit a maximum emission at 500 nm under a 430 nm excitation. Moreover, by controlling their sizes in the process, we find that such a strategy enables the tuning of the emission color of N,P-MoO_x QDs from green to blue. N,P-MoO_x QDs show a significant fluorescence response to pH changes, and also display pH-sensitive near-infrared localized surface plasmon resonance (LSPR) at 866 nm. An effective and simple pH probe with a dual-signal response is achieved using N,P-MoO_x QDs. As environmental sensors, N,P-MoO_x QDs can be applied for sensitive detection of the concentrations of permanganate and captopril, offering the linear range from 0.08 to 25 μM and 0.1 to 31 μM, respectively. Benefitting from the effect of doping nitrogen and phosphorus, the probe could detect a wide range of pH changes (2–9) and is endowed with superior biocompatibility. Further, it is successfully used to “see” the intracellular pH variation by fluorescence confocal imaging. These findings not only demonstrate the achievement of a promising multifunctional probe for biosensing and environmental detection, but also pave the way for the fabrication of transition metal oxide QDs with tunable optical properties.

中文翻译：

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简便快速地合成可发射颜色可调的氧化钼量子点，作为荧光成像和环境监测的多功能探针。

近年来，由于氧化钼量子点（MoO _x QDs）具有诱人的物理和化学特性，它们被视为新兴材料。然而，通过简便的策略仍然需要大量的具有长波长发射的MoO _x QD，但要获得这些挑战更具挑战性。在本文中，我们通过微波辅助快速方法合理设计并成功制备了氮和磷共掺杂的绿色发射MoO _x QDs（N，P-MoO _x QDs）。它们在430 nm激发下在500 nm处显示最大发射。此外，通过在过程中控制它们的大小，我们发现这种策略可以将N，P-MoO _x QD的发射颜色从绿色调整为蓝色。N，P-MoO _x量子点显示出对pH值变化的显着荧光响应，并在866 nm处显示pH敏感的近红外局部表面等离子体共振（LSPR）。使用N，P-MoO _x QD可以实现具有双信号响应的有效且简单的pH探针。N，P-MoO _x作为环境传感器QD可用于高锰酸盐和卡托普利浓度的灵敏检测，线性范围分别为0.08至25μM和0.1至31μM。得益于氮和磷的掺杂，该探针可检测多种pH值（2–9），并具有出色的生物相容性。此外，它已成功用于通过荧光共聚焦成像“观察”细胞内pH的变化。这些发现不仅证明了用于生物传感和环境检测的有前景的多功能探针的成功，而且还为制备具有可调光学性能的过渡金属氧化物量子点铺平了道路。