Split and Use: Structural Isomers for Diagnosis and Therapy

Diagnostics
and therapeutics are generally separate entities in
medicine. Theranostics, agents that provide for both modalities, are
being developed. However, they often require complex syntheses so
as to incorporate within one molecular structure both diagnostic and
therapeutic elements. Moreover, their use is often complicated by
the disparate dosage requirements for diagnosis and therapy. Herein,
we report that closely related porphyrinoid regioisomers produced
from the same 1,3-dipolar cycloaddition reaction give rise to products
that as their corresponding ytterbium­(III) complexes may be split
and used for the separate biological functions that are required for
theranostics. Specifically, the cis isomer is luminescent
and suitable for NIR imaging, while the trans isomer
produces singlet oxygen with a good quantum yield and is thus attractive
for use in photodynamic therapy (PDT). Both in vitro and in vivo experiments
provide support for the complementary biological functions of the
two regioisomers. The present study reveals how ostensibly related
regioisomers may be used to switch between diagnosis and therapy.
More broadly, it serves to highlight a new approach to creating paired
sets of molecules that may be used in combination as effective theranostics.