Determination of fermentable sugars in beer wort by gold nanoparticles@polydopamine: A layer-by-layer approach for Localized Surface Plasmon Resonance measurements at fixed wavelength

• Published in: Talanta (Oxford) Vol. 183; pp. 24 - 32
• Main Authors: Scarano, S., Pascale, E., Palladino, P., Fratini, E., Minunni, M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2018
• Subjects: Food analysis, beer; Gold nanoparticles; Localized surface plasmon resonance; Polydopamine; Refractometer; MNPs; Δλmax; Gold nanoparticles; Sλ; Polydopamine; Food analysis, beer; LSPR; PDA; NPs; Bx; AuNPs; LBL; CVav; SAbs; Localized surface plasmon resonance; DA; RIS; Refractometer; RIU
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2018.02.044

Polydopamine decorated in-situ with Localized Surface Plasmon Resonance (LSPR)-active gold nanoparticles (AuNPs) may extend the applicability of nanoplasmonic materials to original and innovative applications in several fields. Here we report the modification of disposable UV–Vis polystyrene cuvettes with AuNPs@PDA for refractive index LSPR-based measurements. An original layer-by-layer deposition method of PDA followed by AuNPs growth is here developed, showing linear correlation between PDA thickness and optical properties. In particular, the modulation from wavelength sensitivity toward absorbance sensitivity is obtained, allowing measurements at fixed wavelength (578 nm). As applicative example of the photonic cuvettes, the measurement of fermentable sugars in beer wort is here reported. The analytical performance of our approach has been directly compared to portable refractometer of reference, displaying excellent results in terms of the precise estimation of sugars in beer wort (expressed in degrees Brix), reproducibility and sensitivity. The approach may be extended to other materials of interest in LSPR based optical sensors, e.g. optical fibers. [Display omitted] •Polydopamine (PDA) is able to spontaneously reduce Au(III) to gold nanoparticles at their surface.•PDA films decorated with gold nanoparticles can be exploited in LSPR measurements.•A layer-by-layer growth of PDA evidences the correlation between PDA thickness and LSPR behavior.•At certain thickness, absorbance intensity change instead of wavelength shift is successfully obtained.•Measurements of sugars in beer wort are obtained and compared with a portable refractrometer.