Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK.
Analyst. 2019 Sep 9;144(18):5547-5557. doi: 10.1039/c9an00236g.
Upconversion nanoparticles (UCNPs) can provide a vehicle for chemical imaging by coupling chemically sensitive dyes and quenchers. The mechanism for coupling of two anthraquinone dyes, Calcium Red and Alizarin Red S, was investigated as a function of pH. The green emission band of the UCNPs was quenched by a pH-dependent inner filter effect (IFE) while the red emission band remained unchanged and acted as the reference signal for ratiometric pH measurements. Contrary to previous expectation, there was little evidence for a resonance energy transfer (RET) mechanism even when the anthraquinones were attached onto the UCNPs through electrostatic attraction. Since the UCNPs are point emitters, only emitters close to the surface of the UCNP are within the expected Förster distance and UC-RET is <10%. The theoretical and experimental analysis of the interaction between UCNPs and pH-sensitive quenchers will allow the design of UCNP pH sensors for determination of pH via IFE.
上转换纳米粒子（UCNPs）可以通过偶联化学敏感染料和猝灭剂为化学成像提供载体。研究了两种蒽醌染料钙红和茜素红 S 的偶联机制，作为 pH 的函数。UCNPs 的绿色发射带被 pH 依赖性内滤效应（IFE）猝灭，而红色发射带保持不变，作为比率 pH 测量的参考信号。与之前的预期相反，即使蒽醌通过静电吸引附着在 UCNPs 上，也几乎没有证据表明存在共振能量转移（RET）机制。由于 UCNPs 是点发射器，只有靠近 UCNP 表面的发射器在预期的Förster 距离内，并且 UC-RET <10%。UCNPs 和 pH 敏感猝灭剂之间相互作用的理论和实验分析将允许设计 UCNP pH 传感器，通过 IFE 来测定 pH。
