# Deciphering Desorption Pathways and Mechanisms of Peptide Supramolecular Structures Thermodynamically and Kinetically by High-Speed AFM

## TL;DR

This study uses high-speed AFM to observe how peptides detach from surfaces, revealing new desorption pathways and mechanisms important for drug development and nanotechnology.

## Contribution

The study introduces a 'stop-to-activate' desorption mechanism and distinct pathways observed in peptide supramolecular arrays using high-speed AFM.

## Key findings

- Temperature significantly affects peptide desorption and diffusion processes, altering coverage and structure.
- Distinct desorption pathways include no desorption, one- or double-end desorption, and middle desorption of nanowires.
- Desorption characteristics fit classic models, offering insights for drug effects on amyloid disassembly in neurodegenerative diseases.

## Abstract

Studying molecule desorption from solids has attracted
much interest
in crude oil exploitation, self-cleaning nanotechnology, and biomedicine.
Much work on polymer/biopolymer desorption has addressed the effect
of pH, salts, and others on desorption features fitted by established
models. However, molecular desorption pathways and mechanisms are
still poorly understood due to lack of (i) a good model directly revealing
nano- to microscale desorption characteristics and (ii) a powerful
nanotool enabling the capture of every detail within sufficient spatiotemporal
resolution. We utilized well-organized peptide supramolecular arrays
(pSMAs) as a model system and high-speed AFM to investigate molecular
desorption pathways and the mechanism in thermodynamics and kinetics.
Temperature as a key parameter affects both peptide desorption and
diffusion processes, leading to changes of pSMA coverage and ordered-to-disordered
structures. Significantly, we found distinct desorption pathways of
pSMAs in kinetics, including no desorption, one- or double-end desorption,
and middle desorption of nanowires (NWs). Therefore, we proposed a
“stop-to-activate” mechanism. Besides, the desorption
characteristics of single NWs and pSMAs were well fitted by an exponential
curve following classic desorption models. This work provides a good
guideline for studying other molecules’ or assemblies’
desorption and sheds light on investigating drug effects on disassembly
of amyloid protein fibrils in treating neurodegenerative diseases.