Single molecule fluorescence (SMF) studies on conjugated polymers yield enhanced information on exciton dynamics and on the interplay between polymer conformation/morphology and photophysical behavior. SMF studies, however, demand good signal stability, excellent photostability, and high photon yields (a measure of both photostability and brightness) and thus the development of strategies to help conjugated polymers (CPs) meet these requirements is a topic of great interest. Here, we evaluate the effect of a number of triplet quencher additives on the photostability of a 49-mer long poly(phenylene–ethynylene) conjugated polymer bearing carboxylate side groups (PPE-CO₂-49) that is deposited onto 100 nm diameter SiO₂ nanoparticles (NPs). The additives tested include ascorbic acid (AA), β-mercaptoethanol (BME), Ni²⁺, trolox (TX), and a trolox/trolox quinone mixture (TX/TQ), used either with or without an enzymatic oxygen scavenging system (glucose oxidase/catalase, GODCAT). Total internal reflection fluorescence microscopy (TIRFM) studies enabled the determination of the effect of the additives on the rates of photobleaching, the initial intensity, and the total photon output for hundreds of conjugated polymer coated SiO₂ nanoparticles monitored in parallel. Addition of the antioxidant/triplet quenchers AA and TX led to a 3–8-fold increase in the number of photons collected as well as an enhancement of the initial emission intensity, consistent with an increase in the duty cycle attributed to the quenching of triplet states. Removal of oxygen led to an impressive 10–15-fold increase in the photostability relative to buffer, implicating reactive oxygen species (ROS) as an important agent in the photodegradation of PPE-CO₂-49. Combining AA and TX with GODCAT had a deleterious rather than an additive effect, suggesting that an oxidizing agent is in fact necessary to rescue the polymer from reactive intermediates formed via reaction with AA/TX. β-Mercaptoethanol and Ni²⁺ were not found to have useful properties toward the photostabilization of PPE-CO₂-49. The results of this study provide suitable imaging conditions to conduct single molecule imaging experiments on conjugated polyelectrolytes.

中文翻译：

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增强聚苯撑乙炔的光稳定性，用于单颗粒研究†

对共轭聚合物的单分子荧光（SMF）研究产生了激子动力学以及聚合物构象/形态与光物理行为之间相互作用的增强信息。然而，SMF研究要求良好的信号稳定性，出色的光稳定性和高光子产量（光稳定性和亮度的量度），因此开发有助于共轭聚合物（CP）满足这些要求的策略是引起人们极大兴趣的主题。在这里，我们评估了多种三重态猝灭剂添加剂对沉积在直径为100 nm的SiO上的带有羧酸盐侧基（PPE-CO ₂ -49）的49-mer长聚苯撑-乙炔共轭聚合物的光稳定性的影响。_2个纳米粒子（NPs）。所测试的添加剂包括抗坏血酸（AA），β-巯基乙醇（BME），Ni 2 ⁺，trolox（TX）和trolox / trolox醌混合物（TX / TQ），可使用或不使用酶促氧清除系统（葡萄糖氧化酶/过氧化氢酶，GODCAT）。全内反射荧光显微镜（TIRFM）研究使得能够确定添加剂对数百种共轭聚合物涂覆的SiO ₂的光致漂白速率，初始强度和总光子输出的影响并行监控纳米颗粒。添加抗氧化剂/三重态猝灭剂AA和TX导致收集的光子数量增加3-8倍，并增强了初始发射强度，这与三重态猝灭引起的占空比增加是一致的状态。相对于缓冲液，氧气的去除导致光稳定性提高了10-15倍，这意味着活性氧（ROS）是PPE-CO ₂ -49光降解的重要因素。将AA和TX与GODCAT结合使用具有有害作用而不是累加作用，这表明实际上必须使用氧化剂才能将聚合物从通过与AA / TX反应形成的反应性中间体中拯救出来。β-巯基乙醇和Ni ²⁺尚未发现它们对PPE-CO ₂ -49的光稳定具有有用的性质。这项研究的结果为在共轭聚电解质上进行单分子成像实验提供了合适的成像条件。