Synthesis of MBA-Encoded Silver/Silica Core-Shell Nanoparticles as Novel SERS Tags for Biosensing Gibberellin A3 Based on Au@Fe3O4 as Substrate.

Qingmin Wei,Fa Liu,Zhihui Luo,Guobao Huang,Na Li,Jianjuan Lin,Changchun Wen

doi:10.3390/s19235152

Abstract

A surface-enhanced Raman scattering (SERS) tag is proposed for high-sensitivity detection of gibberellin A3 (GA3). Silver nanoparticles (AgNPs) were synthesized using citrate reduction. 4-Mercaptobenzoic acid (MBA) was used for the Raman-labeled molecules, which were coupled to the surface of the AgNPs using sulfydryls. MBA was coated with silica using the Stöber method to prevent leakage. GA3 antibodies were attached via the active functional groups N-Hydroxysuccinimide (NHS) and N-Ethyl-N’-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) to construct a novel immuno-AgNPs@SiO2 SERS tags. The captured SERS substrates were fabricated through Fe3O4 nanoparticles and gold nanoparticles (AuNPs) using chemical methods. These nanoparticles were characterized using ultraviolet-visible spectroscopy (UV–Vis), dynamic light scattering, Raman spectroscopy, transmission electron microscope (TEM), and X-ray diffraction (XRD). This immuno-AgNPs@SiO2 SERS tags has a strong SERS signal based on characterizations via Raman spectroscopy. Based on antigen-antibody reaction, the immuno-Au@Fe3O4 nanoparticles can capture the GA3 and AgNPs@SiO2 SERS tags. Due to the increasing number of captured nanoprobes, the SERS signal from MBA was greatly enhanced, which favored the sensitive detection of GA3. The linear equation for the SERS signal was y = −13635x + 202211 (R2 = 0.9867), and the limit of detection (LOD) was 10−10 M. The proposed SERS tags are also applicable for the detection of other food risk factors.

Highlights

Gibberellins (GAs) is a type of extensive plant growth regulator that promotes plant cell division, enhances plant growth and development, prolongs the preservation and freshness storage of fruit, and increases the output of seedless grapes [1,2]
Due to the increasing number of captured nanoprobes, the surface-enhanced Raman scattering (SERS) signal from Mercaptobenzoic acid (MBA) was greatly enhanced, which favored the sensitive detection of Gibberellin A3 (GA3)
ultraviolet-visible spectroscopy (UV–Vis) absorbance peak for the A3 (GA3). Silver nanoparticles (AgNPs) was observed at 419 nm, which agrees with previous studies [22]

Summary

Introduction

Gibberellins (GAs) is a type of extensive plant growth regulator that promotes plant cell division, enhances plant growth and development, prolongs the preservation and freshness storage of fruit, and increases the output of seedless grapes [1,2]. More than a hundred gibberellins have been isolated and determined in plants, fungi, and bacteria. Despite their structural similarity, only a small number of GAs display biological activity in plants, such as GA3 , GA1 , GA7 , and GA4. As is true for most pesticides, GAs may be harmful to humans who receive excessive exposure. Such damage may not be developed over a short period, there is residual GAs in many fruit and vegetables

Methods

Results

Conclusion