Streptavidin-coated gold nanoparticles: critical role of oligonucleotides on stability and fractal aggregation

Abstract

Gold nanoparticles (AuNPs) exhibit unique properties that can be modulated through a tailored surface functionalization, enabling their targeted use in biochemical sensing and medical diagnostics. In particular, streptavidin-modified AuNPs are increasingly used for biosensing purposes. We report here a study of AuNPs surface-functionalized with streptavidin-biotinylated oligonucleotide, focussing on the role played by the oligonucleotide probes in the stabilization/destabilization of the functionalized nanoparticle dispersion. The behaviour of the modified AuNP dispersion as a consequence of the competitive displacement of the biotinylated oligonucleotide has been investigated and the critical role of displaced oligonucletides in triggering the quasi one-dimensional aggregation of nanoparticles is demonstrated for the first time. The thorough understanding of the fundamental properties of bioconjugated AuNPs is of great importance for the design of highly sensitive and reliable functionalized AuNP-based assays.

Aptamer-based biosensor for food allergen determination using graphene oxide/gold nanocomposite on a paper-assisted analytical device

“…Zeta analysis values were also obtained giving values of −72.41, −38.74 and −46.54 for AuNP, AuNP-SA, and AuNP-SA-M/P/S, respectively. The increase in absolute potential seen when AuNP-SA are further functionalized with the aptamer shows a change in the surface morphology with a more negative molecule, which further attributes to the biotinylated aptamer binding with the SA (D’Agata et al, 2017; Weng and Neethirajan, 2016). From Fig.…”

“…The introduction of the protein SA and its electrostatic adoption onto the surface causes this change in the local refractive index, which in turn causes the shift of the spectral absorbance (Pollitt et al, 2015). The second shift is caused by the introduction of the biotinylated aptamers, which directly bind to the SA, leading to a change in the SA localized refractive index (D’Agata et al, 2017; Pollitt et al, 2015). Inserts on Fig.…”

“…3A and 3B, resulting in the optimum concentration to provide a monolayer of SA for AuNP to be 50 μg/mL of SA. To optimize the aptamer concentration, we first theoretically calculated the minimum amount required for total coverage of the SA cover AuNP by the method introduced in previous studies (Pollitt et al, 2015; D’Agata et al, 2017; Sechi et al, 2013).…”

“…While it is known that SA has 4 possible biotin binding sites, it was estimated that 2 would be incapable of binding with biotin. This assumption is based on the work conducted by D’Agata et al, which listed this effect is related to steric obstruction of binding sites caused by the most likely orientation of absorption for SA onto the surface of the NP (D’Agata et al, 2017). With our known initial concentration of AuNP, an estimate of 38 nM solution of biotinylated aptamers is needed for the total coverage.…”

Оптические Свойства Сферических Металлических Наночастиц, Покрытых Слоем Оксида

“…Например, частота плазмонного резонанса в таких структурах может изменяться в более широких пределах [1,2]. Подобная гибкость в регулировании свойств делает композитные наночастицы особенно перспективными для технических применений: при разработке быстродействующих оптических переключателей для систем телекоммуникации, передачи и обработки информации [3,4], оптических наноантенн [5], в медицине [6], катализе [7], при изготовлении датчиков [8], в солнечной энергетике [9][10][11][12] и других областях.…”