In this study a new pH-responsive nanogel probe containing a complementary nonradiative resonance energy transfer (NRET) fluorophore pair is investigated and its ability to act as a versatile probe of network-related changes in three hydrogels demonstrated. Fluorescent sensing using NRET is a powerful method for studying relationships between Angstrom length-scale structure and macroscopic properties of soft matter. Unfortunately, inclusion of NRET fluorophores into such materials requires material-specific chemistry. Here, low concentrations of preformed nanogel probes were included into hydrogel hosts. Ratiometric photoluminescence (PL) data for the gels labeled with the nanogel probes enabled pH-triggered swelling and deswelling to be studied as well as Ca²⁺-triggered collapse and solute release. PL measurements during compression of a nanogel probe-labeled nanocomposite gel demonstrated mechanochromic behavior and strain sensing. The new nanogel probes have excellent potential for investigating the internal structures of gels and provide a versatile ratiometric fluorescent platform for studying pH and strain.

中文翻译：

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响应式纳米凝胶探针，用于水凝胶中 pH 值和应变的比率荧光传感

在这项研究中，研究了一种新的 pH 响应纳米凝胶探针，该探针包含互补的非辐射共振能量转移 (NRET) 荧光团对，并证明了其作为三种水凝胶中网络相关变化的通用探针的能力。使用 NRET 的荧光传感是研究埃长度尺度结构与软物质宏观性质之间关系的有力方法。不幸的是，将 NRET 荧光团包含在此类材料中需要特定于材料的化学。在这里，低浓度的预制纳米凝胶探针被包含在水凝胶宿主中。用纳米凝胶探针标记的凝胶的比率光致发光 (PL) 数据能够研究 pH 触发的溶胀和去溶胀以及 Ca ²⁺- 触发塌陷和溶质释放。纳米凝胶探针标记的纳米复合凝胶压缩过程中的 PL 测量显示了机械变色行为和应变传感。新的纳米凝胶探针具有研究凝胶内部结构的巨大潜力，并为研究 pH 值和应变提供了一个多功能的比率荧光平台。