Phototheranostics constitute an emerging cancer treatment wherein the core diagnostic and therapeutic functions are integrated into a single photosensitizer (PS). Achieving the full potential of this modality requires being able to tune the photosensitizing properties of the PS in question. Structural modification of the organic framework represents a time-honored strategy for tuning the photophysical features of a given PS system.Here we report an easy-to-implement metal selection approach that allows for fine-tuning of excited-state energy dissipation and phototheranostics functions as exemplified by a set of lanthanide (Ln = Gd, Yb, Er) carbazole-containing porphyrinoid complexes. Femto-and nanosecond time-resolved spectroscopic studies, in conjunction with density functional theory calculations, revealed that the energy dissipation pathways for this set of PSs are highly dependent on the energy gap between the lowest triplet excited state of the ligand and the excited states of the coordinated Ln ions. The Yb complex displayed a balance of deactivation mechanisms that made it attractive as a potential combined photoacoustic imaging and photothermal/photodynamic therapy agent. It was encapsulated into mesoporous silica nanoparticles (MSN) to provide a biocompatible construct, YbL@MSN, which displays a high photothermal conversion efficiency (η = 45%) and a decent singlet oxygen quantum yield (Φ Δ = 31%). Mouse model studies revealed that YbL@MSN allows for both photoacoustic imaging and synergistic photothermal-and photodynamic-therapy-based tumor reduction in vivo. Our results lead us to suggest that metal selection represents a promising approach to fine-tuning the excited state properties and functional features of phototheranostics.

Herein, a series of triphenylamine derivatives (TPAs), which are comprised of electron donor and acceptor moieties, have been exploited as sensitive colorimetric sensors for Cu 2 + , operating via the formation of the corresponding organic radicals through a redox reaction in a mixed solvent system (acetonitrile/water). Further studies indicated that the Cu 2 + recognition triggered organic radical cations were stable in aqueous solution, and can be used as an antibacterial agent for both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) at very low concentrations (10 À 7 M). On comparison with light irradiated photodynamic therapy triggered radicals, the present work reveals that the direct use of radical cations of TPAs is more convenient for practical applications in killing bacteria. This work thus provides new insight into the design of sensitive colorimetric sensors and antibacterial agents.