Plasmonic Au–Ag Janus Nanoparticle Engineered Ratiometric Surface-Enhanced Raman Scattering Aptasensor for Ochratoxin A Detection

Abstract

Ochratoxin A (OTA), a toxic mycotoxin, poses severe risks to environment and human health. Herein, we develop a ratiometric surface-enhanced Raman scattering (SERS) aptasensor based on internal standard (IS) methods for the sensitive and reproducible quantitative detection of OTA. Au−Ag Janus nanoparticles (NPs) are successfully synthesized under the guidance of 2-mercaptobenzoimidazole-5-carboxylic acid (MBIA), which possesses intrinsic Raman signals, thus no additional modification with a Raman reporter on NPs is required. In addition, Au−Ag Janus NPs exhibit amplified and stable SERS activity. MXenes nanosheets generate a unique and stable Raman signal, making them an ideal IS for quantitative Raman analysis. In principle, Au−Ag Janus NPs are assembled with MXenes nanosheets depending on hydrogen bond and the chelation interaction between MXenes nanosheets and OTA aptamers. In the presence of OTA, Au−Ag Janus NPs are dissociated from MXenes nanosheets due to the formation of aptamer/OTA complex, leading to the attenuation of Raman signal of Au−Ag Janus NPs, and meanwhile, the signal of MXenes nanosheets remain constant. Quantitatively, upon correction by the IS Raman signals, sensitive and quantitative detection can be achieved with the limit of detection (LOD) of 1.28 pM for OTA. Our results suggest that this ratiometric SERS aptasensor is a powerful tool which shows great promise for applications in complex systems.

Janus particles: from concepts to environmentally friendly materials and sustainable applications

“…In 2019, two different Janus particle-based approaches were developed for the detection of ochratoxin A (OTA), a toxic mycotoxin produced by several Aspergillus and Penicillium species. Zhao et al reported on a ratiometric SERS (surface-enhanced Raman scattering) aptasensor for the quantitative detection of ochratoxin A based on plasmonic Au-Ag Janus nanoparticles [97]. The Au-Ag Janus NPs were fabricated via sequential growth of silver islands on gold cores.…”

“…The ligand 2-mercaptobenzoimidazole-5-carboxylic acid (MBIA) operates as a Raman reporter, while the Au-Ag Janus NPs enhance the SERS signal. The combination of these JPs with highly stable MXenes nanosheets allowed the introduction of an internal standard for quantitative analysis of ochratoxin A [97]. The Janus NPs were connected to the MXenes nanosheets via hydrogen bonds and chelation interaction between phosphate groups and titanium ions.…”

“…In the presence of OTA, the OTA aptamer preferably interacts with the OTA target, leading to the dissociation of the Janus NPs from the MXenes nanosheets and to a decrease of the SERS signal. The amount of OTA could be then quantified based on the linear correlation between the ratiometric peak intensity of I Janus NP /I MXenes and OTA concentration [97]. This sensitive and reliable approach can be also applied for the quantitative determination of analytes in real systems such as red wine [97].…”

DNA‐Based Plasmonic Heterogeneous Nanostructures: Building, Optical Responses, and Bioapplications

“…MBIA ligands guided the oriented growth of Ag islands, and exhibited amplified SERS signals due to the plasmonic coupling of Au heads and Ag islands. [69] A ratiometric SERS aptasensor was fabricated for OTA detection using SERS-active Au-Ag Janus NPs as detection probes and MXenes as reference probes (Ti 3 C 2 T x , T x represents the surface terminations of OH, F, O) (Figure 8d). In practical detection, sophisticated sampling pretreatment and purification procedures are necessary.…”

Ultrasensitive SERS Detection of Cancer‐Related miRNA‐182 by MXene/MoS2@AuNPs with Controllable Morphology and Optimized Self‐Internal Standards

“…[21][22][23] As an example, Ti 3 C 2 (MXene) was used to combine with analyte molecules by hydrogen bonds, coordination bonds and van der Waals forces to achieve unique and stable Raman characteristic peaks for accurate quantitative detection, which had been used for Ochratoxin A application. [24][25][26][27] Similarly, because of its nanostructure and high electron mobility performance, molybdenum disulfide (MoS 2 ) related materials had also been reported for the detection of Rhodamine 6G with high SERS responses and accuracy. [28,29] In addition, the selection of reference signal was of vital importance to the sensitivity and stability in SERS detection.…”