Determining the selectivity of a tetra-phosphorylated biomimetic peptide towards uranium in the presence of competing cations through the simultaneous coupling of HILIC to ESI-MS and ICP-MS
Résumé
The cyclic tetra-phosphorylated biomimetic peptide (pS1368) has been proposed as a promising starting structure to design decorporating agent of uranyl (UO$_2$$^{2+}$) due to its affinity similar to that of osteopontin (OPN), a target UO$_2$$^{2+}$ protein in vivo. The determination of this peptide selectivity towards UO$_2$$^{2+}$ in the presence of competing endogenous elements is also crucial to validate this proposition. In this context, the selectivity of pS1368 towards UO$_2$$^{2+}$ in the presence of Ca$^{2+}$, Cu$^{2+}$ and Zn$^{2+}$ was determined by applying the simultaneous coupling of hydrophilic interaction chromatography (HILIC) to electrospray ionization (ESI-MS) and inductively coupled plasma (ICP-MS) mass spectrometry. Sr$^{2+}$ was used as Ca$^{2+}$ simulant, providing less challenging ICP-MS measurements. The separation of the complexes by HILIC were firstly set up. The selectivity of pS1368 towards UO$_2$$^{2+}$ was determined in the presence of Sr$^{2+}$, by adding several proportions of this latter to UO$_2$(pS1368). UO$_2$$^{2+}$ was not displaced from UO$_2$(pS1368) even in the presence of a ten-fold excess of Sr$^{2+}$. The same approach has been undertaken to demonstrate the selectivity of pS1368 towards UO$_2$$^{2+}$ in the presence of Cu$^{2+}$, Zn$^{2+}$ and Sr$^{2+}$ as competing endogenous cations. Hence, we showed that pS1368 is selective towards UO$_2$$^{2+}$ in the presence of Sr$^{2+}$, but also in the presence of Cu$^{2+}$ and Zn$^{2+}$. This study highlights the performance of HILIC-ESIMS/ICPMS simultaneous coupling to assess the potential of molecules as decorporating agents of UO$_2$$^{2+}$
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