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Abstract A technique capable of label-free detection, mass spectrometry imaging (MSI) is a powerful tool for spatial investigation of native biomolecules in intact specimens. However, MSI has often been precluded from single-cell applications due to the spatial resolution limit set forth by the physical and instrumental constraints of the method. By taking advantage of the reversible interaction between the analytes and a superabsorbent hydrogel, we have developed a sample preparation and imaging workflow named Gel-Assisted Mass Spectrometry Imaging (GAMSI) to overcome the spatial resolution limits of modern mass spectrometers. With GAMSI, we show that the spatial resolution of MALDI-MSI can be enhanced ~3-6-fold to the sub-micrometer level without changing the existing mass spectrometry hardware or analysis pipeline. This approach will vastly enhance the accessibility of MSI-based spatial analysis at the cellular scale. 

We designed a few polymyxin derivatives which exhibit broad-spectrum antimicrobial activity. Lead compound P1 could disrupt bacterial membranes rapidly without developing resistance, inhibit biofilms formed by E. coli , and exhibit excellent in vivo activity in an MRSA-infected thigh burden mouse model. 

Abstract Through continuous efforts in developing a new class of foldamers, homogeneous sulfono‐γ‐AApeptides have been designed and synthesized using tetraphenylethylene (TPE) moieties attached to the backbone as luminogenic sidechains. Based on previous crystal structures, it is found that these foldamers adopted a left‐handed 4₁₄‐helix. Due to the constraint of the helical scaffold, the rotation of the TPE moieties is restricted, leading to fluorescent emissive properties with high quantum yields not only at the aggregate state but also in solution. Investigation of the relationship between the structure and fluorescence behavior reveals that emission is induced by the combined effect of the aggregation‐induced emission and the rotated restriction from the backbone. Furthermore, as the packing mode of the luminogens can be precisely adjusted by the helical backbone, these foldamers are found to be circularly polarizable with relatively large luminescence dissymmetry factor. Interestingly, possessing cationic amphipathic structures similar to that of host‐defense peptides, these sulfono‐γ‐AApeptides are able to inhibit the growth of Gram‐positive bacteria, methicillin‐resistantStaphylococcus aureusthrough membrane interactions.