Quantitative SERS Detection of Uric Acid via Formation of Precise Plasmonic Nanojunctions within Aggregates of Gold Nanoparticles and Cucurbit[<em>n</em>]uril

Abstract

This work describes a rapid and highly sensitive method for the quantitative detection of an important biomarker, uric acid (UA), via surface-enhanced Raman spectroscopy (SERS) with a low detection limit of ~0.2 M for multiple characteristic peaks in the fingerprint region, using a modular spectrometer. This biosensing scheme is mediated by the host-guest complexation between a macrocycle, cucurbit[7]uril (CB7), and UA, and the subsequent formation of precise plasmonic nanojunctions within the self-assembled Au NP: CB7 nanoaggregates. A facile Au NP synthesis of desirable sizes for SERS substrates has also been performed based on the classical citrate-reduction approach with an option to be facilitated using a lab-built automated synthesizer. This protocol can be readily extended to multiplexed detection of biomarkers in body fluids for clinical applications. INTRODUCTION:Uric acid, which is the end product of metabolism of purine nucleotides, is an important

Fabrication of nanostructured electrodes for electrochemical surface-enhanced Raman spectroscopy (E-SERS): A review

“…Colloidal NPs synthesised via wet chemistry are a staple of SERS [59][60][61][62]. Gold NPs can be cheaply and reproducibly synthesised using techniques such as the Turkevich-Frens method [59][60][61].…”

Quantitative Surface-Enhanced Spectroscopy

“…Additionally, functional groups on SERS substrates can be introduced to increase selective interactions with the molecule of interest, thus reducing the spatial fluctuations of SERS intensities. However, this surface chemistry increases the distance between the SERS substrate and chromophore (18,19), which has the unintended consequence of reducing SERS intensities.…”

“…Minimizing the impacts of electric field variations near SERS substrates promotes quantitative SERS detection. For instance, surface modification can be employed to simultaneously facilitate interactions between target molecules and SERS substrate while also maintaining the analyteto-surface distance (18,19). One successful example of this mechanism to maximize quantitative SERS detection involved using cucurbit [7]uril (CB7) to selectively capture uric acid via host-guest complexation, as shown in Figure 2d (18).…”

SERS biosensors based on cucurbituril-mediated nanoaggregates for wastewater-based epidemiology

“…17,20 Alternatively, CB-Au NP nanocomposites can also be produced by simply mixing solutions of CBs and pre-formed Au NPs stabilised by citrate or chloride ions. 17,20,21 The latter approach is considered more robust and versatile because it decouples the Au NP growth from the CB-mediated self-assembly. In particular, CB-Au NPs can be made from commercially available CB samples and colloidal Au NPs of different sizes stabilised in citrate or phosphate buffer.…”