Methylglyoxal alters collagen fibril nanostiffness and surface potential

Collagen fibrils are fundamental to the mechanical strength and function of biological tissues. However, they are susceptible to changes from non-enzymatic glycation, resulting in the formation of advanced glycation end-products (AGEs) that are not reversible. AGEs accumulate with aging and disease and can adversely impact tissue mechanics and cell-ECM interactions. AGE-crosslinks have been related, on the one hand, to dysregulation of collagen fibril stiffness and damage and, on the other hand, to altered collagen net surface charge as well as impaired cell recognition sites. While prior studies using Kelvin probe force microscopy (KPFM) have shown the effect glycation has on collagen fibril surface potential (i.e., net charge), the combined effect on individual and isolated collagen fibril mechanics, hydration, and surface potential has not been documented. Here, we explore how methylglyoxal (MGO) treatment affects the mechanics and surface potential of individual and isolated collagen fibrils by utilizing atomic force microscopy (AFM) nanoindentation and KPFM. Our results reveal that MGO treatment significantly increases nanostiffness, alters surface potential, and modifies hydration characteristics at the collagen fibril level. These findings underscore the critical impact of AGEs on collagen fibril physicochemical properties, offering insights into pathophysiological mechanical and biochemical alterations with implications for cell mechanotransduction during aging and in diabetes.

Statement of significance

Collagen fibrils are susceptible to glycation, the irreversible reaction of amino acids with sugars. Glycation affects the mechanical properties and surface chemistry of collagen fibrils with adverse alterations in biological tissue mechanics and cell-ECM interactions. Current research on glycation, at the level of individual collagen fibrils, is sparse and has focused either on collagen fibril mechanics, with contradicting evidence, or surface potential. Here, we utilized a multimodal approach combining Kelvin probe force (KPFM) and atomic force microscopy (AFM) to examine how methylglyoxal glycation induces structural, mechanical, and surface potential changes on the same individual and isolated collagen fibrils. This approach helps inform structure-function relationships at the level of individual collagen fibrils.