Understanding hyaluronic acid induced variation of water structure by near-infrared spectroscopy

Qin Dong,Lei Nie,Lian Li,Chen Yu,Siling Huang,Weilu Tian,Hengchang Zang,Hui Zhang,Xueping Guo

doi:10.1038/s41598-020-58417-5

Abstract

In order to understand the hydration effect of hyaluronic acid (HA) in aqueous solution, near-infrared (NIR) spectroscopy was used to investigate the HA aqueous solutions at different concentrations and temperature. As HA concentration was raised, there was a nonlinear change in absorption value in the first overtone region of OH, indicating the changes of hydration water. A reconstructed spectrum based on principal component analysis (PCA) was established and analyzed with the concept of aquaphotomics. The results showed that HA acted as a structure maker to make water molecules arranged in order. Water species with two hydrogen bonds (S2) and three hydrogen bonds (S3) showed the decrease at low concentration range of 0–40 mg/mL, but increased at higher concentration, indicating the difference in water species at different HA concentration. Meanwhile, HA had the ability to improve the thermal stability of water structure, suggesting a potential bio-protective function. This study provides a unique perspective on the molecular interactions between HA and water molecules, which is helpful for understanding the role of HA in life process and may serve as the basis for HA applications.

Highlights

In order to understand the hydration effect of hyaluronic acid (HA) in aqueous solution, near-infrared (NIR) spectroscopy was used to investigate the HA aqueous solutions at different concentrations and temperature
The results showed that HA acted as a structure maker to make water structure ordered in aqueous solutions and different water network was promoted at different HA concentrations
It could be seen the addition of HA caused a decrease in the intensity of the absorption around 6900 cm−1, which is an overlap of the absorption mainly due to the combinations of OH symmetric and antisymmetric stretching modes of various water species[24]

Summary

Introduction

In order to understand the hydration effect of hyaluronic acid (HA) in aqueous solution, near-infrared (NIR) spectroscopy was used to investigate the HA aqueous solutions at different concentrations and temperature. It is known that the structure and morphology of polysaccharides are strongly influenced by water molecules via controlling their conformations, various forms of aggregation, thermal properties and kinetics[5,6] In this respect, the knowledge of the interaction between water and polysaccharide and the hydrated structure is of high importance for understanding its performance in the application. Near-infrared (NIR) spectroscopy, as a powerful analytical method, has unique advantages in studies of molecular structure and interaction[19,20,21,22] It mainly reflects the overtones and combination modes of functional groups containing hydrogen atoms, such as CH, OH and NH, which play a significant role in chemical bonding and other chemical phenomena such as hydrogen transfer, hydrogen bonding[23]. Principal component analysis (PCA) was conducted on the spectra data to extract the information of different water species

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