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Ultrasensitive detection of alpha-fetoprotein (AFP) is critical for the early diagnosis of liver cancer. In this work, a novel surface-enhanced Raman scattering (SERS)-based immunoassay complex has been successfully developed for the detection of AFP by using the Au-Ag alloy nanoparticals and the Ag/AgBr hybrid nanostructure. As the typical bimetal or metal/semiconductor plasmonic materials, besides the strong SERS enhancement characteristics, the Au-Ag alloy nanoparticals exhibit excellent monodispersity and the Ag/AgBr hybrid nanostructure demonstrates good stability. The experimental results show that the SERS-based immunoassay of AFP presents a low limit of detection of 1.86fg/mL and a broad dynamic range from 2fg/mL to 0.8g/mL. Furthermore, the clinical applicability of the proposed SERS-based immunoassay has been assessed by the detection of AFP in the human serum samples of cancer patient and healthy person. The test data are consistent well with that of chemiluminescence immunoassay (CLIA) in the relative errors of 8.82-8.06% and show better detection sensitivity. It reveals that the proposed immunoassay protocol is significant for giving insight into the design of ultrasensitive biosensor and the point-of-care testing of cancers. An ultrasensitive SERS-based sandwich immunoassay platform is constructed by Ag-Au alloy nanoparticles immune probes and Ag/AgBr hybrid nanostructure SERS-active immune substrate to realize the detections of AFP levels in the clinical serum samples. Based on the comprehensive analyses of all the test data, the SERS-based immunoassay protocol exhibits better detection sensitivity than CLIA. It could be potentially applied in the early clinical diagnosis of cancer. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS) on a gold triangular nanoprisms array with precisely controlled size and spacing, fabricated via electron beam lithography was investigated. This SERS substrate shows reasonable efficiency at 785 nm excitation for the detection of p-mercaptoaniline (pMA), and a remarkable homogeneity of the SERS response over the sensing area. The performances of the engineered SERS substrate with human prostate cancer cells has been tested, highlighting excellent sensitivity in comparison to spontaneous Raman scattering, especially in the 1500–1700 cm −1 frequency range, characteristic of the peptide linkage and the neighboring functional groups. The results are promising for biosensing applications, provided the selectivity is enhanced by suitable functionalization approaches. [ABSTRACT FROM AUTHOR]

Brucella is a foodborne pathogen globally affecting both the economy and healthcare. Surface Enhanced Raman Spectroscopy (SERS) nano-biosensing can be a promising strategy for its detection. We combined high-performance quasi-crystal patterned nanocavities for Raman enhancement with the use of covalently immobilized Tbilisi bacteriophages as high-performing bio-receptors. We coupled our efficient SERS nano-biosensor to a Raman system to develop an on-field phage-based bio-sensing platform capable of monitoring the target bacteria. The developed biosensor allowed us to identify Brucella abortus in milk by our portable SERS device. Upon bacterial capture from samples (104 cells), a signal related to the pathogen recognition was observed, proving the concrete applicability of our system for on-site and in-food detection. [ABSTRACT FROM AUTHOR]