Search

Sulfamethazine (SM2) is an antibacterial drug，which has been extensively used in human and veterinary medicine, long-term consumption of which may lead to the accumulation of sulfonamides in the body. Detection of sulfonamides often uses microbiological approaches, mass spectrometry and chromatography, which are expensive and time-consuming. Surface-enhanced Raman scattering-based immunochromatographic assay (SERS-ICA) has been recently applied in the detection. Herein, a Janus-labeled Au nanoparticle with subnanosized SiO 2 -monoclonal antibody and SERS reporter (DTNB) modified simultaneously (mAbAuNpDTNB) has been developed in a SERS-based lateral flow immunosensor, which can be used for rapid, quantitative and ultrasensitive detection of sulfamethazine residue in milk. The mAbAuNpDTNB exhibits a specific array on a paper stripe, which not only identifies sulfamethazine but also straightforwardly exposes the Raman reporter between the AuNps via self-assembly. The detection sensitivity of SERS-ICA for sulfamethazine reached 0.1 pg/mL, which was far below the previously published value by ELISA and the maximum residue limit set by the European Union. The entire SERS-ICA detection for sulfamethazine was completed within 15 min. Furthermore, high accuracy for this assay was exhibited in the spiking experiment with a recovery percentage of 88.1%–112.7%. The results demonstrated that this SERS-ICA can potentially be applied in point-of-care testing as an ultrasensitive and quantitative to semi-quantitative analytical method. [Display omitted] • A Janus-labeled Au nanoparticle (mAbAuNpDTNB) by a SERS-LFIA was reported for the detecting of Sulfamethazine in milk. • The mAbAuNpDTNB exhibits specific array on paper stripe. • The mAbAuNpDTNB recognizes Sulfamethazine and can directly expose Raman reporters between AuNps through self-assembly. • The detection of the SERS-ICA for Sulfamethazine achieved a sensitivity of 0.1 pg/mL. [ABSTRACT FROM AUTHOR]

We report on a facile immunoassay for porcine circovirus type 2 (PCV2) based on surface enhanced Raman scattering (SERS) using multi-branched gold nanoparticles (mb-AuNPs) as substrates. The mb-AuNPs in the immunosensor act as Raman reporters and were prepared via Tris base-induced reduction and subsequent reaction with p-mercaptobenzoic acid (pMBA). They possess good stability and high SERS activity. Subsequently, the modified mb-AuNPs were covalently conjugated to the monoclonal antibody (McAb) against the PCV2 cap protein to form SERS immuno nanoprobes. These were captured in a microtiterplate via a immunoreaction in the presence of target antigens. The effects of antibody concentration, reaction time and temperature on the sensitivity of the immunoassay were investigated. Under optimized assay conditions, the Raman signal intensity at 1,076 cm −1 increases logarithmically with the concentrations of PCV2 in the concentration ranging from 8 × 10 2 to 8 × 10 6 copies per mL. The limit of detection is 8 × 10 2 copies per mL. Compared to conventional detecting methods such as those based on PCR, the method presented here is rapid, facile and very sensitive. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Highlights: [•] The technique enhances the detection sensitivity by inducing the clustering of gold particles on the nitrocellulose strip. [•] The operating time is very short (about 15min). Compared with commercial test strips, the method is 100-fold more sensitive. [•] The method is simple, rapid, economic, sensitive, specific, and results in detection with the naked eye. [•] The technique will be a powerful tool to carried out on-site because of its high sensitivity, specificity, and speed. [Copyright &y& Elsevier]

An ultrasonic method to synthesize gold nanoparticles with uniform size was reported. Effects of ethanol concentration, solution pH, ultrasonic irradiation power, and time on the formation of gold nanoparticles were investigated. The obtained gold nanoparticles were characterized by ultraviolet-visible (UV-vis) absorption spectra and scanning electron microscope (SEM). The method performed in ethanol solution under ultrasonic irradiation is friendly to the environment. Furthermore, a nanogold-labeled probe was used to develop an immunochromatographic method for detection of kanamycin. [ABSTRACT FROM AUTHOR]

A method for surface-enhanced Raman spectroscopy (SERS) sensing of polycyclic aromatic hydrocarbons (PAHs) is reported. Gold nanoparticles (AuNPs) decorated hydrophobic porous glycidyl methacrylate–ethylene dimethacrylate (GMA–EDMA) polymer is developed as the SERS substrate. GMA–EDMA material with porosity and permeability shows rapid and efficient adsorption of PAHs through presumed hydrophobic interaction, which brings the analytes close to the substrate. Meanwhile, the three dimensional porous morphology might benefit AuNPs distribution for high SERS enhancement. Studies on the effects of AuNPs surface coverage on the substrate and time of PAHs–substrate interaction are presented. The qualitative analysis and quantitative tendency of this method for PAHs detection are investigated with anthracene, phenanthrene and pyrene as probe molecules, showing that the characteristic fingerprint vibrational peaks of each PAH can be readily identified, and the limit of detections are 0.93 × 10 −7 , 4.5 × 10 −7 and 1.1 × 10 −7 M respectively. Moreover, the substrate exhibits high reproducibility with the relative standard deviation about 16% in spot and spot SERS intensity. Using this method for rapid screening of PAHs mixture in some water samples are performed well, which might be useful for environmental pollutions monitoring. [ABSTRACT FROM AUTHOR]