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.
Zhu, M.; Lu, D.; Wu, S.; Lian, Q.; Wang, W.; Milani, A.H.; Cui, Z.; Nguyen, N.T.; Chen, M.; Lyon, L.A.; Adlam, D.J.; Freemont, A.J.; Hoyland, J.A.; Saunders, B.R. Responsive Nanogel Probe for Ratiometric Fluorescent Sensing of pH and Strain in Hydrogels. ACS Macro Lett. 2017, 6, 1245-1250.
American Chemical Society
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