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. Author manuscript; available in PMC: 2015 Feb 1.
Published in final edited form as: Ann Biomed Eng. 2013 Dec 3;42(2):243–259. doi: 10.1007/s10439-013-0952-x

Figure 3. Quantum dot – fluorescent protein FRET probes for pH sensing.

Figure 3

(a) Schematic diagram of the FRET interaction between a quantum dot and a GFP-like fluorescent protein. A polyhistidine sequence inserted at the N-terminus of the fluorescent shown here coordinates to the ZnS capping layer of the QD, bringing the two into close proximity. Under excitation of the QD, energy is non-radiatively transferred to the fluorescent protein and sensitized emission is observed. (b) Titration of QD-FP probes containing the FP acceptors mOrange showing increased energy transfer at alkaline pHs with clear isosbestic points. Representative spectra of one of three independent titrations are shown.