X-ray Photoelectron Spectroscopy and Time-of-Flight SIMS Investigations of Hyaluronic Acid Derivatives

Abstract

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and high-resolution X-ray photoelectron spectroscopy (XPS) have been employed to investigate the surface chemistry of solvent cast films of hyaluronic acid (HA) esters. Ethyl, benzyl, dodecyl, and palmityl esters were studied, as well as unmodified HA and partially esterified HA. Ions that were diagnostic of the specific type of esterification were identified within the ToF-SIMS spectra of each material. The XPS spectra were in broad agreement with the bulk stoichiometry, and evidence of surface orientation of esterified polymer was observed in partially esterified HA. Relative ion intensities in the ToF-SIMS spectra confirm that HA esterified with long aliphatic chain components has surfaces rich in the esterified polymer.