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Title: Immobilization of Streptavidin on a Plasmonic Au-TiO2 Thin Film towards an LSPR Biosensing Platform
Authors: Pereira-Silva, Patrícia
Meira, Diana I.
Costa-Barbosa, Augusto
Costa, Diogo
Rodrigues, Marco S. 
Borges, Joel 
Machado, Ana V.
Cavaleiro, Albano 
Sampaio, Paula
Vaz, Filipe 
Keywords: Au-TiO2 thin film; plasmonic biosensor; streptavidin–biotin; LSPR detection
Issue Date: 1-May-2022
Publisher: MDPI
Project: 04650/2020 
info:eu-repo/grantAgreement/FCT/POR_NORTE/2020.08235.BD/PT/Development of nanocomposite ZnO thin films with antibiofilm and antimicrobial properties to prevent pathogens’ transmission 
COVID/BD/ 152169/2021 
info:eu-repo/grantAgreement/FCT/POR_NORTE/SFRH/BD/133513/2017/PT/New generation antigen delivery system for Candida albicans recombinant proteins as a vaccination strategy against systemic fungal infections 
info:eu-repo/grantAgreement/FCT/9471 - RIDTI/PTDC/FIS-MAC/32299/2017/PT/Nanopartículas plasmónicas para deteção biológica 
info:eu-repo/grantAgreement/FCT/POR_NORTE/SFRH/BD/143262/2019/PT/Development of nanoplasmonic thin film biosensors with enhanced sensitivity for detection of Ochratoxin-A 
Serial title, monograph or event: Nanomaterials
Volume: 12
Issue: 9
Abstract: Optical biosensors based on localized surface plasmon resonance (LSPR) are the future of label-free detection methods. This work reports the development of plasmonic thin films, containing Au nanoparticles dispersed in a TiO2 matrix, as platforms for LSPR biosensors. Post-deposition treatments were employed, namely annealing at 400 °C, to develop an LSPR band, and Ar plasma, to improve the sensitivity of the Au-TiO2 thin film. Streptavidin and biotin conjugated with horseradish peroxidase (HRP) were chosen as the model receptor-analyte, to prove the efficiency of the immobilization method and to demonstrate the potential of the LSPR-based biosensor. The Au-TiO2 thin films were activated with O2 plasma, to promote the streptavidin immobilization as a biorecognition element, by increasing the surface hydrophilicity (contact angle drop to 7°). The interaction between biotin and the immobilized streptavidin was confirmed by the detection of HRP activity (average absorbance 1.9 ± 0.6), following a protocol based on enzyme-linked immunosorbent assay (ELISA). Furthermore, an LSPR wavelength shift was detectable (0.8 ± 0.1 nm), resulting from a plasmonic thin-film platform with a refractive index sensitivity estimated to be 33 nm/RIU. The detection of the analyte using these two different methods proves that the functionalization protocol was successful and the Au-TiO2 thin films have the potential to be used as an LSPR platform for label-free biosensors.
ISSN: 2079-4991
DOI: 10.3390/nano12091526
Rights: openAccess
Appears in Collections:I&D CEMMPRE - Artigos em Revistas Internacionais

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