Introducing the Tellurophene-Appended BODIPY: PDT Agent with Mass Cytometry Tracking Capabilities

The
synthesis and characterization of the first BODIPY appended
to the five-membered heterocylic tellurophene [Te] moiety is reported.
By incorporating tellurophene at the meso position,
the tellurophene-appended boron-dipyrromethene dye (BODIPY) acts as
a multimodal agent, becoming a potent photosensitizer with a mass
cytometry tag. To synthesize the compound, we developed a method to
enable late-stage Suzuki–Miyaura coupling by preparing and
isolating tellurophene-2-BPin in a one-step procedure from the parent
tellurophene. Coupling to a meso-substituted BODIPY
functionalized with a pendant aryl bromide provides the desired tellurophene-appended
BODIPY. This compound demonstrated a singlet oxygen quantum yield
of 0.26 ± 0.01 and produced a light dose-dependent cytotoxicity
with nanomolar IC50 values against 2D cultured HeLa cells
and high efficacy against 3D cultured HeLa tumor spheroids, proving
to be a strong photosensitizer. The presence of the tellurophene moiety
could be detected using mass cytometry, thus showcasing the ability
of a tellurophene-appended BODIPY as a novel photodynamic-therapy–mass-cytometry
theranostic agent.