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Measuring Platinum Loading in Proteins with Single Particle icpTOF

Quantifying Platinum Binding on Protein Functionalized Magnetic Microparticles Using Single Particle-ICP-TOF-MS

Bradley et al.
Analytical Methods
DOI: 10.1039/d4ay00268g

Veronica Bradley and her team from the Chemical and Isotopic Mass Spectrometry Group at the Ridge National Laboratory recently introduced a novel analytical method to quantify platinum bound to protein functionalized magnetic microplastics. This work highlights the essential role of the TOFWERK icpTOF and its ability to quasi-simultaneously detect all nuclides, enabling sample-preparation-free differentiation between bound and unbound platinum in solution, as well as quantification of platinum on a particle-by-particle basis.

Platinum (Pt) metal and Pt-based materials and compounds are recognized as critical material for a secure energy and economic future. They are crucial for various applications, including in catalysts for clean energy, industrial production of materials like silicones, and in medicine and medical devices. Economically viable deposits of Pt are rare, and consequently, recycling Pt and platinum-group metals (PGMs) is essential to meet the growing demand for these elements. Proteins and other biological materials have been studied as sorbents for various metals, including PGMs. Additionally, Pt is known to intercalate into DNA, a property utilized in chemotherapeutics, though PGMs and other heavy metals can be extremely toxic. Given the critical importance of PGMs, their essential roles in catalysis, and their diverse biological activities, it is necessary to deepen the understanding of the interactions between Pt and biological materials such as proteins.

Using single particle ICP-TOFMS, both platinum and iron, which are compositions of magnetic microparticles, can be measured concurrently. Magnetic microparticles (1 µm) could be fully characterized, including iron and particle concentration as well as trace element composition. Bulk digestion ICP-MS and single particle ICP-TOFMS were both in agreement with certification values. For platinum samples, the bulk ICP-MS approach overestimated the platinum loading due to free platinum in the samples. Single particle ICP-TOFMS using the icpTOF however enables the differentiation between bound and unbound platinum in solution, as well as the quantification of platinum on a particle by particle basis. This approach of enabling quantification of metal content per particle could also further be applied to other single particle applications.

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