Label-Free Multimodal Protease Detection Based on Protein/Perylene Dye Coassembly and Enzyme-Triggered Disassembly

The development of novel assays for protease sensing plays an important role in clinical diagnostics and therapeutics. Herein, we report a supramolecular platform for label-free protease detection, based on protein/dye self-assembly and enzyme-triggered disassembly. In a typical case, coassembly of protamine sulfate and perylene dye via electrostatic attractions and π–π interactions caused significant colorimetric and fluorescent responses. Subsequent addition of trypsin was found to cleave the amide bonds of protein, triggering the dissociation of protein/dye aggregates and the release of perylene dyes. The enzyme-triggered disassembly was transduced into multiple readouts including absorption, fluorescence, and polarization, which were exploited for trypsin detection and inhibitor testing. This assay was also used for turn-on fluorescence detection of cathepsin B, an enzyme known to be overexpressed in mammalian cancer cells. The integration of supramolecular self-assembly into enzyme detection in this work has provided a novel label-free biosensing platform which is highly sensitive with multimodal readouts. The relative simplicity of the approach avoids the need for time-consuming substrate synthesis, and is also amenable to naked eye detection

Self-Assembled 2D Free-Standing Janus Nanosheets with Single-Layer Thickness

We report the thermodynamically controlled growth of solution-processable and free-standing nanosheets via peptide assembly in two dimensions. By taking advantage of self-sorting between peptide β-strands and hydrocarbon chains, we have demonstrated the formation of Janus 2D structures with single-layer thickness, which enable a predetermined surface heterofunctionalization. A controlled 2D-to-1D morphological transition was achieved by subtly adjusting the intermolecular forces. These nanosheets provide an ideal substrate for the engineering of guest components (e.g., proteins and nanoparticles), where enhanced enzyme activity was observed. We anticipate that sequence-specific programmed peptides will offer promise as design elements for 2D assemblies with face-selective functionalization