Magnetron-Sputtered Niobium Nanoparticles for Molecular Imaging of Brain Tissues through Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

Abstract

Precise molecular identification of specific biomarkers in biological tissues is essential for accurate diagnostics of various diseases, injuries, and other clinically relevant issues. Surface-assisted laser desorption/ionization mass spectrometry imaging (SALDI MSI) has emerged as a powerful tool for biochemical analysis, particularly using noble-metal nanoparticle (NP) matrices. These are often, but not always, synthesized using wet chemistry approaches. Here, we report on NPs of naturally monoisotopic niobium (Nb) as an alternative to more expensive NPs of noble metals in SALDI MSI. The Nb NPs are synthesized by a magnetron sputtering inert gas aggregation technique, which avoids the use of wet chemical pathways and allows the direct deposition of the NPs onto biological specimens. The NPs are partially oxidized and consist of a body-centered cubic (bcc) polycrystalline metal Nb core enclosed by an amorphous Nb 2 O 5 shell. The mean size of the NPs is 25 nm, and the shell thickness is 4 nm. When seeded onto slices of the mouse brain, the Nb NPs form an effective matrix for high-resolution SALDI MSI of complex biological samples in both negative and positive ionization modes. The use of ultrahighresolution mass spectrometry allowed the identification of different Nb adducts and multiple phospholipid ion classes at m/z < 1000, including phosphatidylcholines, phosphatidylethanolamines, phosphatidylserines, phosphatidic acids, and galactoceramides, some of which are not easily accessible from biological tissues with conventional matrix-assisted laser desorption/ionization (MALDI) matrices. This work qualifies Nb NPs as an efficient, accessible, and easy-to-handle matrix for SALDI MSI for the first time. In addition, it highlights the potential utilization of other, yet unexplored transition-metal NPs, motivating their future research.

Temporally and spatially resolved molecular profiling in fingerprint analysis using indium vanadate nanosheets-assisted laser desorption ionization mass spectrometry

“…porous silicon [ 8 , 9 ], carbon-based materials [ 10 – 12 ], metal oxides [ 13 – 16 ], metal-organic frameworks [ 17 , 18 ], and metal nanomaterials [ 19 , 20 ]) several techniques have been developed for the fabrication of SALDI nano-matrices. The efficacy of these nano-matrices has been extensively demonstrated in several applications of SALDI-MS. For instance, Pleskunov et al reported niobium nanoparticles based SALDI-MS method for multiple phospholipids analysis on mouse brain tissue [ 21 ]. Minhas et al prepared nanostructured silicon SALDI-MS to detect anabolic doping agents and their metabolites in saliva and urine [ 22 ].…”

One-step synthesis of photoluminescent nanofluids by direct loading of reactively sputtered cubic ZrN nanoparticles into organic liquids

“…26 For gas-aggregated metal NPs, the formation of a cubic or spherical shape is governed by an interplay between the rate of arrival of metal atoms on the surface of a growing particle and the surface diffusion. 61 Both parameters dynamically change as the NPs thermalize from the close-to-melting point temperature near the magnetron to the ambient temperature at farther distances via collisions with Ar atoms. In the case of reactive sputtering, a high metal-to-nitrogen bond enthalpy provides an additional channel for the energy gain by the NPs, and it can be assumed that the thermalization of NPs proceeds slower, providing close-to-equilibrium conditions for atomic rearrangements and crystallization.…”

Refractory Plasmonics of Reactively Sputtered Hafnium Nitride Nanoparticles: Pushing Limits

“…Metallic Hf and HfN NPs were synthesized using a custom‐built magnetron‐based gas aggregation cluster source (GAS, schematically shown in Figure S1a, Supporting Information) mounted onto a deposition chamber. [ 32,66–70 ] The metallic Hf NPs were synthesized in an argon (Ar) atmosphere, while the HfN NPs were prepared by adding nitrogen to Ar. The magnetron operated in constant current mode at 500 mA throughout all experiments.…”