Elimination of massive aggregation of nanoparticles in the sample of high ionic strength is a prerequisite for the sensitive analysis through a surface-enhanced Raman spectrometry (SERS). We present a system of silver colloid modification composed of two thiolated modifiers (3-mercaptopropionic acid and thiolated polyethylene glycol) both creating a strong Ag-S bond. At their optimal molar ratio, the polymer acts as a steric barrier preventing direct nanoparticle-nanoparticle interaction, while the low-molecular organic acid creates areas accessible for the analyte molecules. Thus, this approach is an excellent tool for sustaining both the colloidal stability and SERS sensitivity. The functionality of the system was demonstrated on the SERS analysis of myoglobin from a saline solution. The favorable creation of hot spots was achieved by laser-induced sintering.

Central European Institute of Technology Masaryk University Kamenice 753 5 602 00 Brno Czech Republic

Institute of Analytical Chemistry of the Czech Academy of Sciences Veveri 967 97 602 00 Brno Czech Republic

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