Intra‐Bacterial Supramolecular Assembly of Peptide With RNA Activates MRI/Fluorescence Imaging and Avoids Drug Resistance

ABSTRACT

Multidrug‐resistant Gram‐negative bacteria present a critical challenge for both diagnosis and therapy because diagnostic and therapeutic molecules have difficulty entering Gram‐negative bacteria, and these molecules can also be expelled by bacteria using efflux pumps. Here, we report a supramolecular intrabacterial assembly peptide (IAP) that enables selective bacterial internalization via siderophore‐like uptake. After internalization, IAP undergoes intra‐bacterial RNA‐triggered transformation from monodisperse molecules to nanofibrils, which bypass efflux pumps and enhance intra‐bacterial retention. The transformation from monodisperse molecules to nanofibrils enhances r ₁ relaxivity of Gd magnetic resonance imaging (MRI) motif of IAP from 9.9 ± 0.2 m

^{− 1} ·s ^{− 1} (monodisperse state) to 24.5 ± 1.1 m ^{− 1} ·s ^{− 1} (nanofibril state), enabling activated T ₁ ‐weighted MRI and fluorescence imaging for Gram‐negative bacteria in vivo. Beyond imaging, the IAP‐RNA nanofibrils inside bacteria inhibit protein synthesis, induce reactive oxygen species accumulation, and disrupt the bacterial envelope. The multiple bacterial death pathways give IAP excellent efficacy against drug‐resistant Gram‐negative in both pneumonia and diabetic wound infection models, and no detectable resistance after prolonged exposure. This work presents a chemically encoded supramolecular strategy for activatable imaging and therapy based on intra‐bacterial supramolecular assembly.