Self-Assembled Platinum Supramolecular Metallacycles Based on a Novel TADF Photosensitizer for Efficient Cancer Photochemotherapy

Abstract

Recently, supramolecular coordination complexes (SCCs) based on photosensitizers as bridging ligands have attracted great attention in cancer therapy owing to their synergistic effect between photodynamic therapy (PDT) and chemotherapy. Herein, a highly emissive supramolecular platinum triangle BTZPy-Pt based on a novel type of photosensitizer BTZPy with thermally activated delayed fluorescence (TADF) was fabricated. The BTZPy and BTZPy-Pt exhibited strong luminescence emission in the visible range with high quantum yields (quantum yields (QYs) for BTZPy and BTZPy-Pt were about 78 and 62% in ethanol solutions, respectively). Additionally, BTZPy had been proved to be an excellent photosensitizer with superior 1 O 2 generation capability (the 1 O 2 generation quantum yield reached up to ca. 95%) for PDT. By the combination of the excellent phototoxicity of BTZPy and the antitumor activity of the Pt center, the platinum triangle BTZPy-Pt demonstrated a highly efficient anticancer performance toward HeLa cells (IC 50 : 0.5 μg mL −1 ). This study not only provides a blueprint to fabricate new types of photosensitizers but also paves a way to design novel SCCs for efficient PDT.

Photoactive and Luminescent Transition Metal Complexes as Anticancer Agents: A Guiding Light in the Search for New and Improved Cancer Treatments

“…Interestingly, this type of complex formed more DNA adducts when exposed to light, rather than being reduced by a biological agent [74]. Some of these dual-action complexes (Figure 9: PT5) are highly fluorescent and indicate local O 2 levels that have enabled researchers to activate (irradiate) the complex when O 2 was abundant, therefore maximizing the photosensitizer effect and ensuring cancer localization [75]. Dinuclear-platinum(II)-diethienylcyclopentene-based complexes (Figure 9: PT6) comprise a unique example of PACT agents, where irradiation by light results in the ligand "opening" and "closing".…”

“…These complexes demonstrated moderate-to-good penetration of spheroids, which is promising for treating tumors some distance from the vasculature (Table 3: PT16) [87]. Photosensitizer platinum complexes: Y-shaped platinum complex PT1 [71]; square planar Pt(II) with weak photosensitizer, where BODIPY = boron-dipyrromethene, PT2 [72] and PT3 [73]; platinum-galadium complex PT4 [74]; triangular tri-platinum complex PT5 [75]; dual-platinum center Pt(II) diethienylcyclopentene PT6 in "open" and "closed" positions [76], PT7 [77], and PT8 [78]; platinum complexes (used to decorate a nanoparticle) PT9 [79] and PT10, [80]; platinum polymers PT11 [81] and PT12 [82]; and platinum complex (used as part of a nanoparticle) PT13 [83].…”

Rational design of a small organic photosensitizer for NIR-I imaging-guided synergistic photodynamic and photothermal therapy

“…37,47 In our previous research, photosensitizers based on BTZ segments exhibited excellent 1 O 2 generation efficiency upon illumination. 48,49 This motiva-…”

Supramolecular Assemblies Showing Thermally Activated Delayed Fluorescence

“…The resulting metallocycle, 9, was then used to form nanoparticles and their use as anticancer agents was evaluated in vitro. [ 76 ] The photophysical properties of the ligand and metallocycle were assessed in degassed ethanol solution; upon excitation at 508 nm, 8 was found to be highly fluorescent, with λ PL at 569 nm, Φ PL of 78%, and τ PL of 8.65 ns. Even in aerated solution, the emission remains strong with Φ PL = 60% and τ PL = 8.30 ns.…”