# Observation of Ice-Like Two-Dimensional Flakes on Self-Assembled Protein Monolayer without Nanoconfinement under Ambient Conditions

## TL;DR

Researchers observed ice-like water layers on protein-coated surfaces under normal conditions, which could help understand how proteins interact with water.

## Contribution

A new model system for studying 2D water layers on protein monolayers without nanoconfinement under ambient conditions.

## Key findings

- Ice-like water layers form on self-assembled monolayers supporting Cytochrome C proteins.
- These water layers can grow in high humidity or melt when heated.
- Higher activation energy for water desorption from Cytochrome C explains the formation of 2D ice-like water.

## Abstract

The two-dimensional (2D) ice-like water layers are formed on the self-assembled monolayers (SAMs), which support the physisorption of Cytochrome C (Cyt C) protein layer under ambient conditions, without the need for nanoconfinement.The morphology, composition, melting, and crystallization processes of the 2D ice-like water are directly characterized using atomic force microscope and nano-atomic force microscopy-infrared spectroscopy.The formation of the 2D ice-like water is attributed to the fact that the activation energy for water desorption from Cyt C is nearly twice as high as that from the SAMs.

The two-dimensional (2D) ice-like water layers are formed on the self-assembled monolayers (SAMs), which support the physisorption of Cytochrome C (Cyt C) protein layer under ambient conditions, without the need for nanoconfinement.

The morphology, composition, melting, and crystallization processes of the 2D ice-like water are directly characterized using atomic force microscope and nano-atomic force microscopy-infrared spectroscopy.

The formation of the 2D ice-like water is attributed to the fact that the activation energy for water desorption from Cyt C is nearly twice as high as that from the SAMs.

The online version contains supplementary material available at 10.1007/s40820-025-01689-1.

Directly correlating the morphology and composition of interfacial water is vital not only for studying water icing under critical conditions but also for understanding the role of protein–water interactions in bio-relevant systems. In this study, we present a model system to study two-dimensional (2D) water layers under ambient conditions by using self-assembled monolayers (SAMs) supporting the physisorption of the Cytochrome C (Cyt C) protein layer. We observed that the 2D island-like water layers were uniformly distributed on the SAMs as characterized by atomic force microscopy, and their composition was confirmed by nano-atomic force microscopy-infrared spectroscopy and Raman spectroscopy. In addition, these 2D flakes could grow under high-humidity conditions or melt upon the introduction of a heat source. The formation of these flakes is attributed to the activation energy for water desorption from the Cyt C being nearly twofold high than that from the SAMs. Our results provide a new and effective method for further understanding the water–protein interactions.

The online version contains supplementary material available at 10.1007/s40820-025-01689-1.