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A novel approach for qualitative biosensing of anti-leptospiral IgG antibodies in human sera using functionalised silver nanoparticles

Authors:

M. H. Dahanayake,

University of Peradeniya, LK
About M. H.
Department of Chemistry
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C. D. Gamage,

University of Peradeniya, LK
About C. D.
Department of Microbiology
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N. M. S. Sirimuthu,

University of Sri Jayewardenepurardenepura, LK
About N. M. S.
Department of Chemistry
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A. C. A. Jayasundera

University of Peradeniya, LK
About A. C. A.
Department of Chemistry
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Abstract

Nanoparticles can interact with biological molecules, thus broadening the applications in the field of medicine. Surface plasmon resonance of nanoparticles in the ultraviolet-visible (UV-visible) region can be applied to identify nanoparticle-protein interactions. This property is used to detect antibodies against leptospirosis, which is an emerging infectious zoonosis in many developing countries and endemic in Sri Lanka. A rapid screening test to detect anti-leptospiral antibodies in human sera by analysing antigen-antibody interactions using UV-visible spectroscopy is reported. The protocol uses hydroxylamine hydrochloride stabilised silver nanoparticles followed by functionalisation with rLigA (recombinant leptospiral immunoglobulin-like protein A) antigens. rLigA-functionalised silver nanoparticles were characterised by UV-visible spectroscopy, Dynamic Light Scattering (DLS), Fourier Transform Infra-Red (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM). A monodispersed solution of LigA-functionalised silver nanoparticles was prepared at 25 °C and 7.0 pH with optimum LigA concentration of 1.5 µg mL-1. This localised surface plasmon resonance (LSPR) biosensor shows a positive response to anti-leptospiral IgG antibodies at optimum conditions in dilutions lower than 1:25 (SD = ± 0.047; 95 % CI = 1.100–1.126). The dilutions of 1:300 to 1:50 IgG antibodies maintained no response compared to nanoparticle conjugate. Furthermore, the non-responsive UV-visible spectra of nanoparticle conjugate with anti-leptospiral antibody negative serum samples confirmed that the conjugate was specific to anti-leptospiral antibodies (SD = ± 0.012; 95 % CI = 1.177–1.183). This novel technique offers  substantial improvement in terms of screening time, which does not take more than 30 minutes, compared to conventional methods, such as ELISA, which consumes 2-3 hours.

How to Cite: Dahanayake, M.H., Gamage, C.D., Sirimuthu, N.M.S. and Jayasundera, A.C.A., 2020. A novel approach for qualitative biosensing of anti-leptospiral IgG antibodies in human sera using functionalised silver nanoparticles. Journal of the National Science Foundation of Sri Lanka, 48(4), pp.437–447. DOI: http://doi.org/10.4038/jnsfsr.v48i4.9642
Published on 31 Dec 2020.
Peer Reviewed

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