Fluorescent gold nanoclusters stabilized by lysozyme: Synthesis and deposition kinetics on silica substrates

• Published in: Journal of luminescence Vol. 277; p. 120912
• Main Authors: Maciejewska-Prończuk, Julia, Oćwieja, Magdalena, Żeliszewska, Paulina, Wasilewska, Monika, Ungor, Ditta, Csapó, Edit, Szyk-Warszyńska, Lilianna, Gajewska, Marta, Chrzanowska, Agnieszka, Dobrzyńska, Joanna, Ivashchenko, Inna, Matras-Postołek, Katarzyna, Adamczyk, Zbigniew
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2025
• Subjects: Electrostatically-driven deposition; Fluorescent gold nanoclusters; Fluorescent layers; Layered materials; Lysozyme; QCM; Self-assembly processes; Fluorescent layers; Electrostatically-driven deposition; Fluorescent gold nanoclusters; Layered materials; QCM; Self-assembly processes; Lysozyme
• ISSN: 0022-2313
• DOI: 10.1016/j.jlumin.2024.120912

Gold nanoclusters suspension were effectively synthesized under alkaline conditions in a chemical reduction process involving gold(III) chloride trihydrate and lysozyme (LYZ) molecules. Their size determined by high-resolution transmission electron microscopy (HR-TEM) was equal to 1.9 ± 0.5 nm. The nanoclusters, referred to as LYZ-Au NCs, were stable at pH below 4 and above 8, exhibiting a hydrodynamic diameter between 8 and 11 nm. The isoelectric point of LYZ-Au NCs appeared at pH 5.0. The suspension showed a pronounced fluorescence characterized by the red-emitting band at 668 nm. The deposition kinetics and stability of LYZ-Au NCs on bare and poly(diallyldimethylammonium chloride) (PDADMAC)-modified silica sensors were studied using quartz crystal microbalance (QCM). The influence of ionic strength, pH, and suspension concentration on the kinetics of LYZ-Au NCs deposition was determined. The significant increase in the maximum coverage of LYZ-Au NCs with ionic strength was attributed to the decreasing range of electrostatic interactions between deposited clusters. Atomic force microscopy (AFM) confirmed the formation of homogeneous layers of LYZ-Au NCs with controlled coverage on bare silica at pH 3.5 and PDADMAC-modified silica. It was shown by confocal microscopy investigations, that these layers also exhibited pronounced fluorescent properties. [Display omitted] •pH and ionic strength-dependent stability of fluorescence LYZ-Au NCs were determined.•Kinetics of LYZ-Au NCs deposition on surfaces and coverage of layers were quantitively determined using gravimetric method.•Red-emitting layers of LYZ-Au NCs were formed on positively and negatively-charged surfaces.