TiO₂ Nanocoral Structures as Versatile Substrates for Surface‐Assisted Laser Desorption/Ionization Mass Spectrometry

Abstract

Matrix-free surface-assisted laser desorption/ionization (SALDI) is a powerful technique for rapidly analyzing a myriad of compounds including biomolecules and polymers. However, previous studies were limited to detecting natural/ organic-based molecules. Biphasic TiO 2 nanocoral (TNC) structures consisting of an anatase base film and a rutile nanocoral layer allow analysis of not only organic compounds and polymers but also inorganic clusters by SALDI mass spectrometry (MS). TNC structures with microscopic surface roughness and porosity, which are indispensable for efficient desorption/ionization (D/I) in SALDI, form on Si wafers immersed in aqueous TiOSO 4 -H 2 O 2 at 80 8C. Various organic and biological molecules with a wide range of molecular weights such as amino acids, hormones, antioxidants, steroids, organic dyes, sugars, drugs, proteins, and polymers are successfully analyzed by using TNC substrates in SALDI-MS. After SALDI-MS, the TNC substrates can be reused for detecting water-soluble molecules. TNC substrates also allow efficient detection of polyoxometalates and gold clusters as representative inorganic clusters. Survival yield measurements are employed to investigate the D/I mechanism of TNC substrates, and these indicate that the rutile nanocoral layer plays a critical role in ensuring efficient D/I. TNC as a versatile substrate for SALDI-MS is a potentially important analysis tool in a wide range of chemical and biological fields.[a] Y.

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2019–2020

“…Biphasic TiO 2 nanocoral (TNC) structures consisting of an anatase base film and a rutile nanocoral layer have been constructed and shown to be suitable for analysis of a wide range of organic compounds including glucose and β‐CD. The TNC substrates could be reused following washing (Nakamura & Soejima, 2019).…”

Construction of a ternary component chip with enhanced desorption efficiency for laser desorption/ionization mass spectrometry based metabolic fingerprinting

“…Unlike the extensively studied matrix formula, the chip substrate is less investigated but valued. The substrate can either be the skeleton for matrices and modifiers or be employed as the matrix (Northen et al, 2007;Nakamura and Soejima, 2019;Jiang et al, 2021). Of note, the nanostructure of the substrate has an impact on the desorption/ ionization process in LDI detection (Ng et al, 2015).…”

Laser Desorption/Ionization Mass Spectrometry as a Potential Tool for Evaluation of Hydroxylation Degree of Various Types of Titanium Dioxide Materials

“…A specific TiO 2 application is in the mass spectrometry, namely as a substrate (solid matrix) in the surface-assisted laser desorption/ionization mass spectrometry [16][17][18][19]. There are also a number of papers reporting TiO 2 surface modification or generation of interesting gas-phase titanium-oxide clusters by subjectingTiO 2 surface to laser beam action [20][21][22][23][24].…”