An AIEgen as an Intrinsic Antibacterial Agent for Light‐Up Detection and Inactivation of Intracellular Gram‐Positive Bacteria

Abstract

Infections caused by Gram-positive bacteria, especially those able to invade and survive in host cells, threaten human health severely. It is therefore highly desirable to develop therapeutics that can selectively target and kill intracellular Gram-positive pathogens with minimal toxicity to host cells. Herein, it is described that the aggregation-induced emission luminogen (AIEgen) TPEPy-Et, containing a positively charged pyridinium group and a hydrophobic tetraphenylethylene fragment, is effective for Gram-positive bacteria detection and elimination. The fluorescence of TPEPy-Et is greatly enhanced after incubation with Gram-positive bacteria, which can be used to detect and trace the bacteria in cells. TPEPy-Et also shows excellent killing effects against both extracellular and intracellular Gram-positive bacteria through a membrane depolarization mechanism. The luminescent antibacterial agent TPEPy-Et is thus promising for diagnosis and therapy against intracellular bacterial infection.

Photoactivated Release of Nitric Oxide and Antimicrobial Peptide Derivatives for Synergistic Therapy of Bacterial Skin Abscesses

“…The density of cationic groups and the ratio of hydrophilic and hydrophobic regions are key factors to the cytotoxicity and antimicrobial activity of amphiphilic copolymers. [ 27 ] In the current study, to modulate the densities of amino groups and isopentanyl grafts, the feeding molar ratios of isopentanoic acid to amino groups of mPEG‐PLL varied from 30% to 70%. Figure S3 in the Supporting Information displays NMR spectra of mPEG‐PLL‐g‐IP with different contents of isopentanyl grafts.…”

Aggregation-Induced Emission Nanoparticles for Single Near-Infrared Light-Triggered Photodynamic and Photothermal Antibacterial Therapy

“…Recently, the findings of the AIE phenomenon have provided an alternative to antibacterial therapy. , This is different from traditional fluorogens in that the fluorophores with an AIE effect (AIEgens) can achieve “off–on” fluorescence properties upon aggregate formation because of the prohibition of energy dissipation and restriction of intramolecular motion (RIM). Owing to the RIM mechanism, AIEgens could also generate sufficient ROS in the aggregate state, resulting in AIE-based PSs being more promising for clinical PDT applications. − Although the AIE effect mainly restricts the rotor-like structure from intramolecular motion, some free rotor-like structures can also be used. Most importantly, some AIEgens with NIR emission have been developed to generate photothermal and photoacoustic effects by consuming nonradiative excited state energies and transforming them to heat .…”

Bioactive AIEgens Tailored for Specific and Sensitive Theranostics of Gram-Positive Bacterial Infection

“…After identification, timely killing is critical for treating bacterial infections . Antimicrobial photodynamic therapy (APDT), as a promising alternative to conventional antibiotics in the treatment of bacterial infections, has been clinically proven to be a noninvasive and spatial temporal controllable therapeutic mode by photo-triggered generation of reactive oxygen species (ROS). − Photosensitizers (PSs) in APDT generate ROS under light irradiation and further induce irreversible oxidative stress to damage surrounding essential biomolecules and finally lead to bacterial death. − Generally, there are two main paths for the generation of ROS, namely, electron transfer and energy transfer. − Type I ROS including ·OH, O 2 •– , and H 2 O 2 are generated by an electron transfer path with lower oxygen dependence . Meanwhile, type II ROS mainly referred to singlet oxygen ( 1 O 2 ) are obtained by an energy transfer process and also the prevailing ROS produced by most reported PSs. − Since hypoxia is the obvious feature of a bacterial infection microenvironment, type I PSs are increasingly favored by researchers due to their low oxygen dependence. − Therefore, developing superior type I PSs with a specific identification and killing effect toward Gram-positive bacteria shows great potential in antibacterial and even antitumor application.…”