Saturation Transfer (CEST) and Biosensor
Imaging of Redundant Deviation in Shifts (BIRDS) biosensing methods differ respectively by detecting
exchangeable and non-exchangeable protons on the agent. Given that CEST
and BIRDS properties observed from the same paramagnetic agent are
complimentary, we describe a novel approach for high-resolution pH imaging
using dual agents of europium and thulium complexed with DOTA-tetraglycinate.
In vitro results test the hypothesis that ratiometric paraCEST attributes are
conserved when temperature from paraBIRDS is detected simultaneously, enabling absolute
pH imaging. In vivo results in glioblastoma demonstrate feasibility of this
dual paraCEST-paraBIRDS biosensing method for high-resolution pH imaging.