A dual-mode lateral flow immunoassay by ultrahigh signal-to background ratio SERS probes for nitrofurazone metabolites ultrasensitive detection

In this work, an ultra-sensitive lateral flow immunoassay (LFIA) with SERS/colorimetric dual signal mode was constructed for the detection of nitrofurazone metabolites, an antibiotic prohibited in animal-origin foods. Au@4-MBN@AgNRs nano-sandwich structural signal tag integrates the unique advantages of high signal-to-background ratio and anti-matrix interference through geometric control of SERS tag and nanoengineering adjustment of chemical composition. Under the optimal conditions, the detection limits of nitrofurazone metabolites by SERS/colorimetric dual-mode LFIA were 20 pg/mL (colorimetric mode) and 0.08 pg/mL (SERS mode). Excitingly, the vLOD of the colorimetric signal improved by a factor of 100 compared to Au NPs-based LFIA. In this study, the proposed dual-mode LFIA was successfully applied to the on-site real-time detection of honey, milk powder, and chicken. It is anticipated that with low background interference and anti-matrix interference output signal, our proposed dual-mode strategy can pave an innovative pathway for the fabrication of a powerful biosensor.

A piggyBac-based TANGO GFP assay for high throughput screening of GPCR ligands in live cells

BACKGROUND

GPCRs are considered essential for various physiological processes and have been the most productive drug targets. Therefore, development of the methods of GPCR ligands screening is a high priority for pharmaceutical industries and research institutions.

METHODS

We developed a potential method (piggyBac-TANGO) based on the TANGO and PRESTO-TANGO assays. The system was optimized with a piggyBac transposon as a transgene vehicle, and eGFP was used as a reporter instead of luciferase. The assay was validated in the HEK 293T and U87-MG cell lines and antagonist activities of the compounds were assessed. The transgene copy number and long-term stability were evaluated by qPCR. Then, we performed a DRD2-targeted screening for natural products using the piggyBac-TANGO assay.

RESULTS

The validation assay showed that using the piggyBac transposon as a transgene vehicle produced high signal-to-background ratio and stable readout confirmed by investigation of the transgene copy number and long-term stability. Use of eGFP instead of luciferase as a reporter enabled to create a high throughput system suitable for live cells. Moreover, the piggyBac-TANGO assay permitted versatile detection of antagonist activity of compounds and was not limited to a particular cell type. With the use of the piggyBac-TANGO assay, we have successfully identified a novel agonist of DRD2.

CONCLUSION

Thus, the results indicate that the piggyBac-TANGO method is a user-friendly, robust and imaging-based assay that provides a novel approach to high throughput GPCR-targeted ligand screening and drug development.