An international research team led by Hiroshima University has developed a technique that can reveal extremely early changes in human skin collagen, long before the damage becomes visible under conventional imaging.
The findings, published in ACS Nano on July 16, 2026, suggest that collagen begins losing its precise molecular organization before its fibers become thinner, fragmented, or disconnected. In other words, skin tissue may appear structurally intact even after important changes have already begun at a deeper level.
Hidden Damage Inside Skin Collagen
Collagen is the main structural protein in skin. It forms an intricate network that helps tissue remain strong, flexible, and resistant to physical stress.
Its structure is organized across several scales. Individual molecules assemble into larger bundles, which then form the fibers that support the skin. Because of this layered arrangement, collagen is described as a hierarchical material.
Most traditional imaging methods focus on visible features of that network. They can detect fibers that have thinned, broken apart, or lost their connections. However, those changes tend to appear relatively late in the remodeling process.
The new research indicates that collagen can lose its underlying structural order while the visible fiber network still looks largely unchanged.
“One way to think about our findings is that conventional imaging methods can show the ‘bricks’ of a collagen structure, but they may miss subtle changes in how those bricks are arranged,” said Ali Haider, first author of the study and a graduate research fellow at Hiroshima University’s International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM2). “It’s similar to detecting changes in the arrangement of words and sentences in a book before any pages appear damaged or missing.”
Detecting Collagen’s Structural Handedness
To identify these hidden changes, the researchers combined advanced optical imaging with chiroptical spectroscopy.
Chiroptical methods examine how molecules interact with polarized light. They are especially useful for studying chirality, a property sometimes described as structural handedness. Much like a person’s left and right hands mirror one another but cannot be perfectly superimposed, many biological structures have a preferred orientation.
Collagen has this kind of organized handedness at both the molecular and larger structural levels. When that organization begins to deteriorate, the tissue may lose important functional properties even if its overall amount of collagen remains unchanged.
The team used synchrotron radiation vacuum-ultraviolet circular dichroism (SR-VUVCD) and multi-dimensional quantum cascade laser vibrational circular dichroism (MultiD-QCL-VCD). By combining these methods with imaging, the researchers were able to measure collagen abundance and structural coherence within the same section of tissue.
Collagen Can Remain While Its Order Disappears
The analysis revealed a clear separation between the quantity of collagen and the quality of its organization.
The tissue samples maintained much of their total collagen content and surface coverage, even after the coherence of their supramolecular chirality had deteriorated substantially. This means that measuring only how much collagen is present may provide an incomplete picture of tissue health.
A sample can still contain abundant collagen while the protein’s internal architecture is already breaking down.
“The key message of this paper is that collagen should not be viewed only as a visible fiber network but as a hierarchical material whose function depends on organization across multiple length scales,” said Katsuya Inoue, a professor at WPI-SKCM2 who is one of the study’s corresponding authors. “Our study shows that advanced correlative methods can reveal changes in this hidden organization that are not apparent from morphology alone.”
Earlier Clues to Tissue Deterioration
The researchers ultimately hope to build a broader framework that connects molecular chirality, supramolecular organization, and the large scale architecture of tissue.
Such a system could help scientists evaluate tissue integrity before major structural damage becomes irreversible. It may also offer new insights into wound healing, medical treatments, and the design of biomaterials that imitate or interact with biological tissue.
Rather than waiting until collagen fibers visibly thin or fragment, future researchers may be able to identify the earliest warning signs by examining how the molecules are arranged.
An International Research Collaboration
The study was conducted by Ali Haider, Yusuke Kochi, Andrew K. Schulz, Kuya Aoyama, Aiko Sada, Hisako Sato, Elisabetta Matsumoto, Malcolm Kadodwala, Koichi Matsuo, and Katsuya Inoue.
The researchers represent Hiroshima University (including WPI-SKCM², the Graduate School of Advanced Science and Engineering, the Chirality Research Center, and the Research Institute for Synchrotron Radiation Science), the Max Planck Institute for Intelligent Systems, Kyushu University, Kumamoto University, Ehime University, the Georgia Institute of Technology, and the University of Glasgow.
The collaboration brought together specialists from Japan, Germany, the United States, and the United Kingdom.
This work was supported by WPI-SKCM2, Institut Henri Poincaré, LabEx CARMIN, and the Alexander von Humboldt Foundation.
