Cavitands Endow All-Dielectric Beads With Selectivity for Plasmon-Free Enhanced Raman Detection of Nε-Methylated Lysine

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• 作者：Ivano Alessandri ; Elisa Biavardi ; Alessandra Gianoncelli ; Paolo Bergese ; Enrico Dalcanale
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：June 22, 2016
• 年：2016
• 卷：8
• 期：24
• 页码：14944-14951
• 全文大小：513K
• 年卷期：0
• ISSN：1944-8252

文摘

SiO₂/TiO₂ microbeads (T-rex) are promising materials for plasmon-free surface-enhanced Raman scattering (SERS), offering several key advantages in biodiagnostics. In this paper we report the combination of T-rex beads with tetraphosphonate cavitands (Tiiii), which imparts selectivity toward N_ε-methylated lysine. SERS experiments demonstrated the efficiency and selectivity of the T-rex-Tiiii assays in detecting methylated lysine hydrochloride (N_ε-Me-Lys-Fmoc) from aqueous solutions, even in the presence of the parent Lys-Fmoc hydrochloride as interferent. The negative results obtained in control experiments using TSiiii ruled out any other form of surface recognition or preferential physisorption. MALDI-TOF analyses on the beads exposed to N_ε-Me-Lys-Fmoc revealed the presence of the Tiiii•N_ε-Me-Lys-Fmoc complex. Raman analyses based on the intensity ratio of N_ε-Me-Lys-Fmoc and cavitand-specific modes resulted in a dose–response plot, which allowed for estimating the concentration of N_ε-methylated lysine from initial solutions in the 1 × 10^–3 to 1 × 10^–5 M range. These results can set the basis for the development of new Raman assays for epigenetic diagnostics.