Antibacterial Theranostic Agents with Negligible Living Cell Invasiveness: AIE-Active Cationic Amphiphiles Regulated by Alkyl Chain Engineering

Abstract

To address the threat of bacterial infection in the following post-antibiotic era, developing effective antibacterial approaches is of utmost urgency. Theranostic medicine integrating diagnosis and therapy is a promising protocol to fight against pathogenic bacteria. But numerous reported antibacterial theranostic materials are disclosed to be trapped in the excessive invasiveness to living mammal cells, leading to false positives and possible biosafety risks. Herein, a series of cationic pyridinium-substituted phosphindole oxide derivatives featuring aggregation-induced emission are designed, and alkyl chain engineering is conducted to finely tune their hydrophobicity and investigate their bioaffinity preference for living mammal cells and pathogenic bacteria. Most importantly, an efficient theranostic agent (PyBu-PIO) is acquired that is free from living cell invasiveness with negligible cytotoxicity and yet holds a good affinity for Gram-positive bacteria, including drug-resistant strains, with a superior inactivating effect. Externally applying PyBu-PIO onto Gram-positive bacteria-infected skin wounds can achieve creditable imaging effects and successfully accelerate the healing processes with reliable biosafety. This work proposes living cell invasiveness as a criterion for antibacterial theranostic materials and provides important enlightenment for the design of antibacterial theranostic materials.

Short-Wavelength Aggregation-Induced Emission Photosensitizers for Solid Tumor Therapy: Enhanced with White-Light Fiber Optic

“…[26][27][28][29][30] Benefiting from many AIE-based photosensitizers have been successfully designed and presented, which largely block non-radiative pathways while promoting both radiative pathways and ISC processes, further enhancing ROS production. [31][32][33][34][35][36][37] In addition, photobleaching has no significant effect on the ROS production capacity of AIEgens, but photosensitivity of traditional photosensitizers such as Ce6 is greatly reduced after photobleaching. 38,39 Furthermore, AIEgens has other additional memorable features, including the distinguishable emission from the visible to near-infrared region, photothermal conversion and fluorescence sensing based on assembly or disassembly.…”

AIEgens for microorganism‐related visualization and therapy

“…Zhuang and Zhao et al designed and synthesized a series of cationic pyridiniumsubstituted phosphindole oxide (PIO) derivatives, which exhibited typical AIE properties. 42 Specifically, their bioaffinity preference for pathogens over living mammalian cells was tuned by a rational alkyl chain engineering (Figure 5A). The results turned out that PyBu-PIO was free of living cell invasiveness, had negligible cytotoxicity, and had a high affinity toward Gram-positive bacteria, including drug-resistant strains.…”

“…Zhuang and Zhao et al. designed and synthesized a series of cationic pyridinium‐substituted phosphindole oxide (PIO) derivatives, which exhibited typical AIE properties 42 . Specifically, their bioaffinity preference for pathogens over living mammalian cells was tuned by a rational alkyl chain engineering (Figure 5A).…”

A simple strategy for the efficient design of mitochondria-targeting NIR-II phototheranostics

“…AIE photosensitizers with cation motifs such as anion–π interactions have drawn our attention due to their ample ROS generation through intersystem crossing (ISC) channels and their organelle-targeting ability via charge interaction. 29–32 Therefore, we boldly speculate that NIR-II AIEgens with cation charge will favor PDT/PTT and cellular organelle specificity.…”