Bare laser-synthesized Au-based nanoparticles as non-disturbing SERS probes for Bacteria Identification

The ability of noble metal-based nanoparticles (Au, Ag) to drastically enhance Raman scattering from molecules placed near metal surface, termed as Surface Enhanced Raman Scattering (SERS), is widely used for identification of trace amounts of biological materials in biomedical, food safety and security applications. However, conventional nanoparticles synthesized by colloidal chemistry are typically contaminated by non-biocompatible by-products (surfactants, anions), which can have negative impacts on many live objects under examination (cells, bacteria) and thus decrease the precision of bioidentification. In this paper, we explore novel ultrapure laser-synthesized Au-based nanomaterials, including Au nanoparticles and AuSi hybrid nanostructures, as mobile SERS probes in tasks of bacteria detection. We show that these Au-based nanomaterials can efficiently enhance Raman signals from model R6G molecules, while the enhancement factor depends on the content of Au in nanoparticle composition. Profiting from the observed enhancement and purity of laser-synthesized nanomaterials, we demonstrate successful identification of two types of bacteria (Listeria innocua and Escherichia coli). The obtained results promise less disturbing studies of biological systems based on good biocompatibility of contamination-free laser-synthesized nanomaterials.

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