Smart Chemiluminescence Probes and Dual-Amplification of Signal for Detection of Amyloid Beta Species in Alzheimer’s Disease Model

Fluorescence and chemiluminescence imaging are the most widely applied optical emissive imaging

methods in biomedical research. “Smart” (turn-on) fluorescence imaging has been routinely used for in

vitro, cellular, and in vivo imaging; however, smart chemiluminescence imaging has been rarely explored.

In this report, we designed chemiluminescence probe ADLumin-1 and validated that ADLumin-1 was a

smart chemiluminescence probe for amyloid beta (Ab) species, evidenced by a 216-fold amplification of

chemiluminescence intensity upon mixing with Abs in vitro. In vivo two photon imaging indicated that

ADLumin-1 could efficiently cross blood-brain- barrier (BBB) and provided excellent contrast both for Ab

plaques and cerebral amyloid angiopathy (CAA). In vivo whole brain imaging showed that the

chemiluminescence signal of ADLumin-1 from 5-month-old transgenic AD (5xFAD) mice was 1.80-fold

higher than that from the age-matched wild-type mice. Moreover, we demonstrated that it was feasible to

further dually-amplify signal via chemiluminescence resonance energy transfer (DAS-CRET) using two

non-conjugated smart probes (ADLumin-1 and CRANAD-3) in solutions, brain homogenates, and in vivo

whole brain imaging. Our results showed that DAS-CRET could provide a 2.25-fold margin between 5-

month-old 5xFAD mice and wild type mice. To our knowledge, this is the first report that a

chemiluminescence probe could be used for detecting Ab species both in vitro and in vivo. Although

ADLumin-1 was designed for Abs, we believe that our strategy could be potentially extended to a wide

range of targets, including other aggregating-prone proteins. Notably, our results suggested that the

strategies for turning-on fluorescence could be used for amplifying chemiluminescence, and we believe that

our studies could inspire considerably more research on chemiluminescence imaging

Abstract