Chemical-biological sensing using directly fabricated Au(Pd) core@layer NPs for enhanced SERS detection of low bacterial concentrations

The Au(Pd) core@layer colloidal nanoparticles were paired utilizing the pulsed laser ablation method to reduce a PdCl₂ solution to develop SERS substrates with high enhancement factors for detecting low bacterial concentrations on nanopyramidal Si. Surface plasmon resonance tests were performed using a UV-Vis spectrophotometer where it was established that increasing in PdCl₂ concentration reduced the signal from the Au peak. TEM analysis further identified bimetallic particles composed of spherical Au(Pd) core@layer where the thickness depends on the concentration of PdCl₂. Thus, according to these results, a procedure for synthesizing Au(Pd) core@layer nanoparticles was described. In SERS sensing of low concentrations (10 ¹ CFU/ml), E . coli showed highest bacterial enhancement factor (E.F = 1.7 x 10 ⁵ ) over S. epidermidis (E.F = 5.9 x 10 ⁴ ).These results indicate that Au(Pd) core@layer nanoparticles coupled with nanostructured Si is effective in enhancing the Raman signal and detection of the bacteria.