Amplifying the signal of localized surface plasmon resonance sensing for the sensitive detection of Escherichia coli O157:H7

Abstract

Gold nanorods (Au NRs) based localized surface plasmon resonance (LSPR) sensors have been widely employed in various fields including biology, environment and food safety detection, but their size- and shape-dependent sensitivity limits their practical applications in sensing and biological detection. In our present work, we proposed an approach to maximally amplify the signal of Au NRs based LSPR sensing by coating an optimized thickness of mesoporous silica onto Au NRs. The plasmonic peaks of Au NRs@SiO2 with different shell thickness showed finely linear response to the change of surrounding refractive index. The optimized thickness of mesoporous silica of Au NRs@SiO2 not only provided high stability for LSPR sensor,but also displayed much higher sensitivity (390 nm/RIU) than values of Au NRs from previous reports. The obtained Au NRs@SiO2 based LSPR sensor was further used in practical application for selectively detection of the E. coli O157:H7, and the detection limit achieved 10 CFU, which is much lower than conventional methods such as electrochemical methods and lateral-flow immunochromatography.

Gold Nanorods for LSPR Biosensing: Synthesis, Coating by Silica, and Bioanalytical Applications

“…When coated by silica, the surface charge of nanoparticles becomes negative at physiological pH due to the low PZC of silica, allowing for an opposite electrostatic adsorption [ 134 ]. Antibodies have been physisorbed to negatively charged silica-coated AuNR [ 135 ]. Here, again, no study on the long-term stability of the resulting antibody-AuNR bioconjugates was performed.…”

“…Most of the papers we review in this section deal with gold nanorods without silica coating. Indeed, up to now, only two examples of biosensors based on AuNR@SiO 2 have been reported in the literature [ 135 , 175 ]. Both of them involve antibodies as bioreceptors and in one of the cases, it was demonstrated that the presence of a thin SiO 2 shell not only provided a protective layer and increased the shelf life of the particles, but also improved the overall efficiency of the biosensor [ 135 ].…”

Protection of silver and gold LSPR biosensors in corrosive NaCl environment by short alkanethiol molecules; characterized by extinction spectrum, helium ion microscopy and SERS

“…There have been reports that under some circumstance, a protective layer can enhance the gure of merit when coated with Au and SiO 2 . 65,76,77 Thus, we conclude that the 1-BT treatment not only succeeded in stabilizing the sensor but also lead to improvements in the gure of merit, 208.9 and 170.43 nm per RIU for the 17 and 22 nm thick AgLSPR sensors respectively. Fig.…”

Fluorescence-Free Biosensor Methods in Detection of Food Pathogens with a Special Focus on Listeria monocytogenes

“…Localized surface plasmon resonance (LSPR) is an indirect method able to enhance SPR sensitivity [ 36 , 37 , 38 ]. The LSPR approach has been applied to label-free, real-time pathogen detection, and small, cost-effective LSPR biosensor systems have been constructed.…”