Molecular Imaging and Biology

, Volume 14, Issue 3, pp 293–300

Spectral Unmixing Imaging of Wavelength-Responsive Fluorescent Probes: An Application for the Real-Time Report of Amyloid Beta Species in Alzheimer’s Disease

Research Article

DOI: 10.1007/s11307-011-0501-7

Cite this article as:
Ran, C. & Moore, A. Mol Imaging Biol (2012) 14: 293. doi:10.1007/s11307-011-0501-7



The goal of the study was to investigate a method for the real-time assessment of a target concentration in vivo using a combination of a spectral unmixing technique and a fluorescent probe specific for amyloid beta (Aβ) species, the biomarkers for Alzheimer’s disease (AD).


The probe CRANAD-3 has a significant emission wavelength shift upon binding to Aβ species. It was used to differentiate a bound probe from an unbound probe in a phantom, ex vivo in brain slices and whole brain, and in vivo in a transgenic mouse model of AD.


The ex vivo unmixing imaging of AD brain clearly showed differential distribution of the bound and unbound probes between the brain tissue and blood vessels. The in vivo unmixed signals of bound CRANAD-3 reached a plateau with increasing dosage, demonstrating that these signals correspond to Aβ content, not probe injected dose.


This study provided evidence that signals processed by the spectral unmixing technique could be used as a real-time reporter of Aβ species loading in vivo and ex vivo.

Key words

Spectral unmixingAlzheimer’s diseaseWavelength-responsive fluorescent probe

Supplementary material

11307_2011_501_MOESM1_ESM.pdf (221 kb)
SI Fig. 1Raw images of phantom imaging with CRANAD-3 and Aβ 42 species in PBS buffer. The raw images were obtained with 535-nm excitation and with 14 emission filters ranging from 580 to 840 nm. (PDF 220 kb)
11307_2011_501_MOESM2_ESM.pdf (316 kb)
SI Fig. 2Representative raw image sequence of in vivo imaging of an APP/PS1 mouse with CRANAD-3 (Ex = 570 nm, Em = 620–840 nm with 12 emission filters). (PDF 316 kb)
11307_2011_501_MOESM3_ESM.pdf (1.7 mb)
SI Fig. 3Fluorescent microscopic images of ex vivo brain slice of APP/PS1 mouse. a Image of Aβ plaque distribution in whole brain slice with ×2 lens. b Image of Aβ plaque in the cortex area (white box in a) with ×10 lens. (PDF 1751 kb)

Copyright information

© Academy of Molecular Imaging and Society for Molecular Imaging 2011

Authors and Affiliations

  1. 1.Molecular Imaging Laboratory, MGH/MIT/HMS Athinoula A. Martinos Center for Biomedical Imaging, Department of RadiologyMassachusetts General Hospital/Harvard Medical SchoolBostonUSA