We have developed a sheet-like pH imaging sensor based on a flexible and physically adhesive polymer thin film (referred to as a “pH sensing nanosheet”). The pH sensing nanosheet was composed of two films: one is a pH-sensitive layer-by-layer (LbL) film constructed from fluorescein-conjugated poly(acrylic acid) and poly(allylamine hydrochloride) and the other is a pH-insensitive film made from Nile red-embedded poly(D,L-lactic acid). The pH sensing nanosheet enabled the ratiometric imaging of pH changes in a leaf (500 × 500 μm²), namely the apoplastic ion milieu responding to an external NaCl stress. It was successfully mapped out that the alkalization of the leaf apoplast spread from the leaf base to the tip at 20 min after the stimulation and the pH value increased up to approximately pH 6.3 from less than pH 4.5 within 60 min when a 100 mM NaCl aqueous solution was added. The pH sensing nanosheet should be useful for energy metabolic mapping in tissue biology.

中文翻译：

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具有聚电解质多层纳米片的植物叶片的细胞外 pH 成像†

我们开发了一种基于柔性和物理粘合聚合物薄膜（称为“pH 传感纳米片”）的片状 pH 成像传感器。pH传感纳米片由两层薄膜组成：一层是由荧光素共轭聚（丙烯酸）和聚（烯丙胺盐酸盐）构成的对pH敏感的逐层（LbL）薄膜，另一种是对pH不敏感的薄膜由尼罗红包埋聚（D，L-乳酸）制成。pH 传感纳米片能够对叶片中的 pH 变化（500 × 500 μm ²），即质外体离子环境对外部 NaCl 应力作出反应。结果表明，在刺激后 20 分钟，叶质外体的碱化从叶基部扩散到叶尖，当 100 mM NaCl 水溶液在 60 分钟内，pH 值从小于 pH 4.5 增加到大约 pH 6.3。加入溶液。pH 传感纳米片应可用于组织生物学中的能量代谢绘图。