Fig. 7. In vitro validation of CRET with ADLumin-1/CRANAD-3 pair.
a Proposed CRET model between ADLumin-1 and CRANAD-3 with Aβ40 fibrils. Two nonconjugated molecules upon binding to fibrils to bring ADLumin-1 (Donor) close enough to CRANAD-3 (Acceptor) to initiate CRET; b Spectrum of the CRET pair with Aβ40 fibrils in PBS (red line), and the peak was consistent with the emission of CRANAD-3 in the presence of Aβ40 fibrils. Chemiluminescence spectrum of ADLumin-1 with Aβ40 fibrils (black line); and spectrum of the mixture of ADLumin-1 and CRANAD-3 without Aβ40 fibrils (pink line). The FRETing efficiency was very high, evident by the low intensity at 500–560 nm range; c Spectrum of the CRET pair in brain homogenate (red line), evident by a decrease in ADLumin-1 emission (black line) and increase in CRANAD-3 emission; d Spectral unmixing of DAS-CRET to separate the contribution from ADLumin-1 only (Unmixed #1), and CRET (Unmixed #2) and CRANAD-3 only (Unmixed #3).