Naphthalimide-based multifunctional AIEgens: Selective, fast, and wash-free fluorescence tracking and identification of Gram-positive bacteria

Pathogenic infections, particularly caused by Gram-positive bacteria (G(+)), pose a serious threat to human health, and therefore the fast and accurate discrimination of Gthorn bacteria from Gram-negative bacteria (G(-)) and fungi is highly desirable. Organic molecules with facile synthesis, robust photostability, good biocompatibility, and high selectivity toward pathogens are urgently needed in the clinical diagnosis and therapy. To this end, herein we report the synthesis of two naphthalimide-based bioprobes named tetraphenylethylene-naphthalimide (TPE-NIM) and triphenylamine-naphthalimide (TPA-NIM) with aggregation-induced emission (AIE) characteristic. First, the staining capacity of the designed AIEgens toward six kinds of bacteria and two kinds of fungi was evaluated. Both TPE-NIM and TPA-NIM showed a high degree of binding/imaging selectivity for Gthorn bacteria over G(-) bacteria and fungi via a wash-free protocol. Second, the two AIEgens had the ability to visualize the biofilms formed by Gthorn bacteria (Staphylococcus aureus) and can quickly track the Gthorn bacteria (Staphylococcus aureus) in red blood cell suspensions. Third, we have revealed that electrostatic attraction and hydrophobic interaction both contribute to the selective binding of the AIEgens toward Gthorn bacteria. In view of the high binding/imaging specificity toward Gthorn bacteria, low hemolysis rates, and low toxicity toward the bacterial cells, these AIEgens can be applied for the clinical detection of pathogenic infections caused by G(+) bacteria and broaden the theranostic applications of AIE materials. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

This study synthesized two naphthalimide-based bioprobes with aggregation-induced emission (AIE) characteristic, showing high binding/imaging selectivity towards Gthorn bacteria over G(-) bacteria and fungi via a wash-free protocol. The AIEgens were able to visualize biofilms formed by Gthorn bacteria and rapidly track the bacteria in red blood cell suspensions. The selective binding of the AIEgens towards Gthorn bacteria was found to be contributed by electrostatic attraction and hydrophobic interaction.