AIE Multinuclear Ir(III) Complexes for Biocompatible Organic Nanoparticles with Highly Enhanced Photodynamic Performance

Abstract

The singlet oxygen (1O2) generation ability of a photosensitizer (PS) is pivotal for photodynamic therapy (PDT). Transition metal complexes are effective PSs, owing to their high 1O2 generation ability. However, non‐negligible cellular toxicity, poor biocompatibility, and easy aggregation in water limit their biomedical applications. In this work, a series of red‐emitting aggregation‐induced emission (AIE) Ir(III) complexes containing different numbers of Ir centers (mono‐, di‐, and trinuclear) and the corresponding nanoparticles (NPs) AIE‐NPs, are designed and synthesized. The increase of 1O2 generation ability is in line with the increasing number of Ir centers. Compared with the pure Ir(III) complexes, the corresponding NPs offer multiple advantages: (i) brighter emission; (ii) higher phosphorescence quantum yields; (iii) longer excited lifetime; (iv) higher 1O2 generation ability; (v) better biocompatibility; and (vi) superior cellular uptake. Both in vitro and in vivo experiments corroborate that AIE‐NPs with three iridium centers possess potent cytotoxicity toward cancer cells and effective inhibition of tumor growth. To the best of knowledge, this work is the first example of NPs of multinuclear AIE Ir(III) complexes as PSs for enhanced PDT. This study offers a new method to improve the efficiency of PSs for clinical cancer treatments.

Aggregation-Induced Generation of Reactive Oxygen Species: Mechanism and Photosensitizer Construction

“…The two kinds of moiety are bridged through different units such as phenyl and thiophene groups to regulate the molecular electron effect. As shown in Table 1 (AIE–PSs 9 – 19 ), most of the AIE (donor)-acceptor AIE–PSs are constructed in this way and exhibit good performance [ 42 , 56 , 58 , 59 ]. For instance, 10 and 12 , respectively, showed strong AIE with the emission enhancement up to 290-fold and 34-fold, large two-photon absorption cross-section up to 477 and 303 GM, respectively, and highly specific targeting to mitochondria in living cells with good biocompatibility [ 55 ].…”

Enhanced three-photon activity triggered by the AIE behaviour of a novel terpyridine-based Zn(ii) complex bearing a thiophene bridge

“…To evaluate the potential biological application of probe DZ1 , imaging experiments were carried out in HepG2 cells. First, HepG2 cells hatched for 20 min in different concentrations of DZ1 solution 30. We found that DZ1 passed through the cell membrane and stained mitochondria with an optimum concentration of 10 μM (Fig.…”

Bright red aggregation-induced emission nanoparticles for multifunctional applications in cancer therapy

“…[46][47][48][49][50][51][52][53][54] Recently, our group obtained three red-emitting AIEgen nanoparticles (NPs) with higher brightness, enhanced 1 O 2 generation, and better biocompatibility compared to the pure iridium(III) complexes. 55 These precedents make AIE NPs with purely organic D-A units particularly suitable as smart PSs to successfully obtain an "all-in-one" (image-guided PDT, ultrafast staining and long-term tracing) system.…”