Flower-like Ag was formed by nanosheet self-assembly as a SERS-active substrate and was utilized for the preparation of flower-like Ag@molecularly imprinted polymers (MIPs) as a surface-enhanced Raman scattering (SERS) sensor. Based on the combination of the molecular imprinting technique and SERS technology, the flower-like Ag@MIPs with high sensitivity and excellent selectivity were used as SERS substrates for the detection of glibenclamide. The imprinted layer could effectively protect the flower-like Ag from oxidation and thereby may improve the stability of the SERS substrate. The intensities of the characteristic peaks obtained for the flower-like Ag@MIPs were higher than that of flower-like Ag. By applying the flower-like Ag@MIPs as an efficient and ultra-sensitive SERS platform, glibenclamide was quantitatively detected in trace concentrations as low as 1 ng mL−1. Furthermore, the SERS enhancement for the flower-like Ag@MIPs was due to the synergetic effect between electromagnetic enhancement and chemical enhancement. We believe that this reliable method can open up new opportunities for practical chemosensor or biosensor applications.
Qinzhi Wang,Zhihao Xu,Yijian Zhao,Hui Zhangsun,Tong Bu,Changqiu Zhang,Xin Wang,Li Wang
Surface-enhanced Raman scattering (SERS) enables azo dye monitoring become rapid and efficient. However, the high cost, low efficiency and poor recyclability of SERS substrate limit its practical application. Herein, we propose a facile strategy to develop self-cleaning carbon cloth as a high-performance and reusable SERS substrate through in-situ growth of leaf-like metal-organic framework (L-MOF) and one-step electro-deposition of flower-like Ag nanoparticles (CC-L-MOF@F-Ag) followed by chemical modification for SERS detection of congo red (CR), chrysoidine (CYD) and acid orange II (AO II) in soft drinks. Taking advantages of superhydrophobicity and SERS-active F-Ag, the prepared self-cleaning CC-L-MOF@F-Ag not only avoids the diffusion-random problem and further boosts sensitivity, but also yields excellent self-cleaning property through facile washing with water, endowing its good reusability and stability. Furthermore, this substrate can realize quantitative detection of CR, CYD and AO II with low limits of detection (0.013 μM for CR, 0.017 μM for CYD and 0.0067 μM for AO II) and wide linear detection range (0.1 – 1000 μM for CR, 0.1 – 1000 μM for CYD and 0.01 – 100 μM for AO II). Meanwhile, CR, CYD and AO II in six soft drinks were also successfully detected with satisfactory recoveries. This method provides a potential and cost-effective strategy to develop advanced SERS sensing device for effective monitoring azo dyes in soft drinks.
In this work, a label-free electrochemical immunosensor was developed for the quantitative detection of carcinoembryonic antigen (CEA). Flower-like Ag/MoS 2 /rGO nanocomposites were employed as the signal amplification platform of the designed immunosensor for the first time. Due to the synergistic effect between molybdenum disulfide (MoS 2 ), reduced graphene oxide (rGO) and Ag nanoparticles (NPs), Ag/MoS 2 /rGO nanocomposites could provide a high sensitivity for the label-free electrochemical immunosensor. The detection mechanism was based on the monitoring of the electrocatalytic current response change towards the reduction of hydrogen peroxide (H 2 O 2 ) when immunoreaction occurred on the surface of the electrode modified with Ag/MoS 2 /rGO nanocomposites. Using amperometric i-t curve to record the electrocatalytic process, the proposed immunosensor achieved an ultrasensitive and specific detection of CEA with a low detection limit of 1.6 fg/mL. Under optimal conditions, the fabricated immunosensor exhibited acceptable reproducibility, selectivity and excellent stability. This designed immunosensor could provide an effective method in the clinical diagnosis of other tumor markers.
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