Evaluation of Structure–Function Relationships of Aggregation-Induced Emission Luminogens for Simultaneous Dual Applications of Specific Discrimination and Efficient Photodynamic Killing of Gram-Positive Bacteria

Abstract

Bacterial infectious diseases, especially those caused by Gram-positive bacteria, have been seriously threatening human health. Preparation of a multifunctional system bearing both rapid bacterial differentiation and effective antibacterial effects is highly in demand, but remains a severe challenge. Herein, we rationally designed and successfully developed a sequence of aggregation-induced emission luminogens (AIEgens) with orderly enhanced D–A strength. Evaluation of structure–function relationships reveals that AIEgens having intrinsic positive charge and proper ClogP value are able to stain Gram-positive bacteria. Meanwhile, one of the presented AIEgens (TTPy) can generate reactive oxygen species (ROS) in extraordinarily high efficiency under white light irradiation due to the smaller singlet–triplet energy gap. Thanks to the NIR emission, excellent specificity to Gram-positive bacteria, and effective ROS generation efficiency, TTPy has been proved to perform well in selective photodynamic killing of Gram-positive bacteria in vitro, such as S. aureus and S. epidermidis, even in S. aureus-infected rat wounds.

One stone, three birds: one AIEgen with three colors for fast differentiation of three pathogens

“…31,32 To date, AIEgens have enjoyed great successes in bioanalyte sensing with the merits of low background, high sensitivity and good photobleaching resistance. [33][34][35][36][37][38][39] The multirotor structures of AIEgens also endow them with high sensitivity to the surrounding microenvironment. In particular, when bearing twisted D-A structures, AIEgens can adapt different molecular congurations and show diverse uorescence color responses to the microenvironments based on the TICT effect.…”

Aggregation‐Induced Emission: Recent Advances in Materials and Biomedical Applications

“…While the earlier designs of type‐I AIE theranostic probes have achieved PDT killing of bacteria, selectively killing of Gram‐positive or Gram‐negative bacteria has not been achieved . Inspired by the design of imaging platform containing multiple type‐I charged AIEgens for bacterial identification, a sequence of type‐I probes, TPy, TPPy, TTPy, MeOTTPy, and TPE‐TTPy, were designed by adding different functional groups on the triphenylamine (TPA) core and positively charged pyridinium moiety, to screen out the best probe for targeting and efficient PDT killing of Gram‐positive bacteria (Figure a) . After incubation with Gram‐positive S. aureus and Gram‐negative E. coli , it was found that TPy, TPPy, TTPy, and MeOTTPy could selectively labelling the Gram‐positive S. aureus (Figure b).…”

“…*** P <0.001, unpaired Student's t test (two‐tailed). e) Photographs of the agar plates of E. coli and S. aureus with/without TTPy (2×10 −6 m ) and white light (60 mW cm −2 ) treatment . Copyright 2016 American Chemical Society.…”

Immunological Effects of Aggregation-Induced Emission Materials

“…Lee et al. ( 15 , 51 ) use AIE-active molecules called TTVP with good water solubility, NIR emission, and extremely high generation efficiency of ROS for the first time to carry out bacterial identification and photodynamic antibacterial research. The research indicates that TTVP can selectively target gram-positive bacteria through a washing-free and ultrafast staining procedure after the incubation period of 3 s, which shows ultrafast bacterial identification.…”