Soft-interfacial concentration gradients drive size-/time-scale desorption characteristics and mechanisms of...

Self-assembled monolayers of biomolecules, particularly peptides, are important for a wide range of applications, including surface coatings, biosensing, and bioelectronics. The performance of peptide two-dimensional crystal patterns on solid substrates as molecular scaffolds strongly depends on the stability of the assemblies, which is closely related to their desorption behavior. However, investigation on peptide desorption remains poorly understood, especially across distinct sizes and time scales. Here, we investigated the desorption characteristics and underlying mechanisms of peptide assemblies on graphite/MoS₂ driven by water incubation mediated soft-interfacial concentration gradient (CG). We captured, recorded and quantified morphological and structural changes in peptide nanowires (pNWs) using three key parameters: surface coverage, width and length of pNWs. We further examined the effects of peptide sequence, substrate, humidity, and temperature on the desorption behaviors and characteristics of peptide assemblies by modulating interpeptide and peptide-substrate interactions. Quantitative analysis of the time-dependent changes in surface coverage revealed exponential desorption kinetics with an exponent index of 0.51 ± 0.05. In addition, we observed a water-assisted phase transition of pNWs, performed quantitative analysis, and mapped the corresponding energy landscape. Finally, we propose a multistep desorption mechanism involving desorption/adsorption, attachment/detachment, and phase transitions accompanied by peptide diffusion. This work provides fundamental insight into CG-induced peptide desorption on graphite surfaces and helps bridge the knowledge gap between nanoscale desorption phenomena and behavior at micro--/macroscales. It also highlights the potential applications of peptide-based systems in self-cleaning surfaces, controllable release, and related technologies.