Shixi Zhang,Yuhan Zhang,Jiaye Jiang,Mathias Charconnet,Yuan Peng,Lei Zhang,Charles H. Lawrie
The biosensing field faces a significant challenge in efficiently detecting multiple analytes in a single diagnostic sample in order to compete with other established multiplex molecular diagnostic technologies such as PCR and ELISA. In response, we have developed a colorimetric nanobiosensor based on multiple morphological forms of functionalized gold nanoparticles (AuNPs) for the simultaneous detection of the influenza virus and SARS-CoV-2 virus. Gold nanospheres (GNSp) were modified with oligonucleotides specific for the influenza A virus, while gold nanoshells (GNSh) were modified with oligonucleotides specific for the SARS-CoV-2 virus. In the presence of their respective targets, AuNPs remain stable due to DNA–DNA interactions; conversely, in the absence of targets, AuNPs aggregate. Consequently, the hybrid system exhibits an indigo color with the SARS-CoV-2 target, a blue color with the Influenza A target, and a purple color with both targets, visible to the naked eye. Analytical sensitivity was 100 nM, and no cross-reactivity was observed with potentially confounding pathogens. This approach holds great promise for the simultaneous identification of multiple pathogens in a rapid manner without the need for equipment or trained personnel.
Quick and highly sensitive detection of the SARS-CoV-2 virus can efficiently reduce the possibility of viral spreading. In this study, a differential-phase surface plasmon resonance (SPR) biosensor is constructed to directly detect the SARS-CoV-2 virus. The SARS-CoV-2 spike protein antibodies are applied as bioprobes and functionalized on Au film, forming a sensing surface. A numerical analysis of the phase shifts of the SPR interferogram, termed the index of phase shifts (IoPS), is presented, which does not depend on a reference beam or an s-component beam. The IoPS can sensitively reflect small changes in the refractive index (as low as 3.75 × 10−10 RIU) when NaCl solution is used as an analyte. The limit of detection (LOD) of the proposed SPR biosensor in detecting the SARS-CoV-2 S protein is 1 ag mL−1. In comparison with a SARS-CoV-2 negative control (NC) sample collected from healthy people, which has an IoPS of ΔϕNC = 39°, the SPR biosensor shows a very strong response to the SARS-CoV-2 virus collected from infected people with a phase shift of ΔϕIoPS = 566°. To further improve the detection sensitivity, a sandwich structure is designed by applying SARS-CoV-2 spike protein antibody functionalized gold nanoparticles (anti-S@AuNPs). This reduces the LOD for the detection of the SARS-CoV-2 S protein to 0.1 ag mL−1.
Outbreaks of infectious viruses offer a formidable challenge to public healthcare systems and early detection of viruses is essential for preventing virus propagation. In this work, an ultrasensitive plasmon-enhanced fluorescence resonance energy transfer (FRET) biosensor based on core-shell upconversion nanoparticle (csUCNP) and gold nanoparticle (AuNP) for accurate detection of SARS-CoV-2 viral RNA is presented. In this biodetection assay, the Tm 3+ /Er 3+ co-doped csUCNP NaGdF 4 :Yb/Tm@NaYF 4 :Yb/Er acts as an energy donor and AuNP serves as an energy acceptor. The upconversion emission of Tm 3+ and the design of the core-shell structure led to a simultaneous surface plasmon effect of AuNP. The localized surface plasmon resonance (LSPR) arising from collective oscillations of free electrons significantly enhanced FRET efficiency between Er 3+ and AuNP. The as-prepared biosensor obtained a limit of detection (LOD) as low as 750 a m , indicating that the integration of FRET and surface plasmon into one biodetection assay significantly boosted the sensitivity of the biosensor. In addition, samples extracted from clinical samples are also utilized to validate the effectiveness of the biosensor. Therefore, this innovative plasmon-enhanced FRET biosensor based on Tm 3+ /Er 3+ co-doped csUCNP may pave the way for rapid and accurate biodetection applications.
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