Broad-spectrum pathogenic bacteria SERS sensing with face-centered high-index facets Au CPNCs & microarray chips: A novel platform able to achieve dual-readout detection

Abstract

Non-specificity and inadequate quantitative capability are the primary challenges faced by the surface-enhanced Raman scattering (SERS) technique, especially when it comes to detecting bacteria in real samples. Herein, a novel face-centered Au Convex Polyhedral Nanocrystal (Au CPNC) with high-index facets and its assembly Au CPNCs microarray chip were designed and fabricated to address these challenges, within the process where 4-mercaptophenylboronic acid (4-MPBA) was utilized as a multifunctional element. The as-prepared Au CPNC possesses anisotropic raised edges enjoying tunable localized surface plasmon resonance modes for SERS enhancement. Then we obtained long-region ordered Au CPNCs microarrays equipping even greater “hot spots” with a SERS enhancement factor (EF) up to 5.38 × 10⁷. The constructed SERS probes excellently leveraged the outstanding SERS performance of Au CPNC and the superior functions of 4-MPBA, which enabled the differences among the bacterial “fingerprints” to be highlighted. Through partial least squares discriminant analysis (PLS-DA), we successfully identified Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Listeria monocytogenes with achieving limits of detection (LODs) in spiked whole blood samples of 3, 1, 2, and 2 cfu/mL, respectively. Notably, the LODs for all samples by SERS mapping visual readout mode were as low as 10 cfu/mL. In practical applications, our method demonstrated its efficacy by 100 % accurately classifying (20 cases) of real blood samples. Altogether, the theoretical significance and application value of this study reside in providing fundamental insights and approaches for the development of pathogenic bacteria detection field.