Since the time of Faraday’s experiments, the optical response of plasmonic nanofluids has been tailored by the shape, size, concentration, and material of nanoparticles (NPs), or by mixing different types...

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In this communication, a new gas aggregation cluster source is introduced equipped with post cylindrical magnetron. The rotation of magnetic circuit improves the usage of cylindrical copper target in terms of its homogenous consumption. Copper nanoparticles were successfully synthesized. Their deposition rate fluctuates at slow rotations of magnetic circuit. Cyclic trapping and release of nanoparticles from electrostatic capture zones are likely responsible for this effect. The instabilities are not observed at higher rotation speeds. The argon flow is found to be very complex within the cluster source; however, it seems crucial for its operation. The efficiency of transport of nanoparticles and their size increase with gas flow. The highest values of deposition rate of around 19 mg/h are obtained.

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.

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