Randomly positioned gold nanoparticles as fluorescence enhancers in apta-immunosensor for malaria test

Minopoli, Antonio; Ventura, Bartolomeo Della; Campanile, Raffaele; Tanner, Julian A.; Offenhäusser, Andreas; Mayer, Dirk; Velotta, R.

doi:10.1007/s00604-021-04746-9

Cited by 22 publications

(17 citation statements)

References 44 publications

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“…[172] Although such platforms do not yield a strong EF PEF because of the lack of plasmonic hot spots, their simplicity in fabrication and optical versatility make them appealing for PEF-based biosensing applications. Minopoli et al [173] realized a plasmonic platform consisting of AuNPs randomly immobilized onto a silane-modified substrate apt to be used as fluorescence enhancer (Figure 14a-1,a-2). The intense near-field offered by of analyte concentration, a-2) experimental (red continuous line) and simulated (gold continuous line) extinction spectrum of the substrate, excitation (dotted blue line) and emission (dashed green line) spectrum of the fluorophore, and a-3) calibration curve (fluorescence intensity vs PfLDH concentration in whole blood) of the biosensor (the inset shows a scheme of the apta-immunoassay sandwich configuration).…”

Section: Pef-based Biosensingmentioning

confidence: 99%

“…Adapted under the terms of the CC-BY license. [173] Copyright 2021, The Authors, published by Springer Nature. b-1) Schematic representation of the experimental bioassay procedure, b-2) corrected PEF enhancement obtained inside the enhancement region volume (dashed gray line) (the inset shows the 0.04% plastic spectrum) and b-3) calibration curve for the evaluation of protease activity of trypsin proteolytic enzymes.…”

Section: Pef-based Biosensingmentioning

confidence: 99%

“…Figure 14. a-1) SEM image of randomly positioned AuNPs onto a glass substrate (top panel) and example of fluorescence image acquired at 1 × 10 −6 mof analyte concentration, a-2) experimental (red continuous line) and simulated (gold continuous line) extinction spectrum of the substrate, excitation (dotted blue line) and emission (dashed green line) spectrum of the fluorophore, and a-3) calibration curve (fluorescence intensity vs PfLDH concentration in whole blood) of the biosensor (the inset shows a scheme of the apta-immunoassay sandwich configuration). Adapted under the terms of the CC-BY license [173]. Copyright 2021, The Authors, published by Springer Nature.…”

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confidence: 99%

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Nanostructured Surfaces as Plasmonic Biosensors: A Review

Minopoli

Acunzo

Ventura

et al. 2021

Adv Materials Inter

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are the main features exhibited by metal nanostructures thereby opening up the possibility for manipulating light at nanometric scale, well below the diffraction limit. [1] So far, the tremendous potentialities of the plasmon-related effects have been already represented a breakthrough in many application fields such as cancer treatment, [2] ultrasensitive molecule detection, [3] integrated circuitry, [4] quantum optics, [5] optoelectronics, [6] photovoltaics. [7] Several types of plasmonic nanostructures are being conceived these days aiming at improving the performance of plasmon-based devices. [8,9] At the basis of the nonpropagating plasmon phenomena there is the localized surface plasmon resonance (LSPR), namely, the collective oscillation of the conduction electron cloud against the metal core. [10] The plasmonic properties of metal nanomaterials strongly depend on the nanostructure geometry, arrangement, and environment. For instance, exotic nanostructures such as nanocages, nanoscaffolds, and bow-tie nanoantennas exhibit higher field enhancement than conventional nanoparticles with smooth surfaces thereby representing a considerable advantage in applications relying on signal amplification such as surface-enhanced Raman spectroscopy (SERS), [11,12] surface-enhanced infrared absorption (SEIRA), [13,14] and plasmon-enhanced fluorescence (PEF). [15,16] In addition, when nanostructures are ordered in periodic arrays, new modes can arise as a result of the near-or far-field coupling among the localized plasmons so as to activate hybrid effects such as coupled LSPR (c-LSPR) [17,18] and surface lattice resonance (SLR), [19][20][21] respectively. Besides, plasmonic properties offered by metamaterials were recently investigated and sparked considerable interest since they demonstrated to offer significantly better performance as compared to metal-based nanostructures in many fields of applications such as biosensing, [22] photonics, [23] photovoltaics, [24] and optoelectronics. [25] Nevertheless, the actual implications are still far-reaching for many scientific and engineering fields due to their complexity and low awareness. [25] Therefore, the possibility to tune the optical response of a nanostructure by tailoring the material, shape, and size, as well as the pattern architecture, is spurring the researchers to explore new approaches, in terms of both nanofabrication and nanoapplications, in order to go beyond the current limits of many techniques.The aim of the present work is to provide a comprehension of this growing field of research and to convey the main features of the nanostructured surfaces to biosensing applications.Conventional laboratory techniques exhibit impressive sensing performance and still constitute an irreplaceable tool in bioanalytics. Nevertheless, high costs, time consumption, and need for well-equipped laboratories and skilled personnel make highly desirable to explore novel strategies to carry out biochemical analyses. In this regard, biosensor-based methods represent a promising appr...

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Section: Pef-based Biosensingmentioning

confidence: 99%

Section: Pef-based Biosensingmentioning

confidence: 99%

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confidence: 99%

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Nanostructured Surfaces as Plasmonic Biosensors: A Review

Minopoli

Acunzo

Ventura

et al. 2021

Adv Materials Inter

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“…In addition, PIT requires a UV-induced immobilization step, which without extreme modification of the SPR device, is not possible to do "live" during measurements. [39,40]…”

Section: Evaluation and Binding Capacity Of Aunp Surfaces Using Antibodiesmentioning

confidence: 99%

Gold Albumin Sandwich Structures for Enhanced Biosensing Using Surface Plasmon Resonance

Rüger

Keusgen

Vornicescu

2021

Physica Status Solidi (a)

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The sensitivity of surface plasmon resonance (SPR) is limited by physico‐optical constraints like the quality of the optical elements, resolution of the optical detection element, and temperature control, but also by the surface area of the gold layer, which serves for interaction events. To increase the utilized sensing surface area, gold‐coated chips are loaded with gold nanoparticles (AuNPs). The nanoparticles are synthesized by two different methods and in different sizes. Experimental conditions are elaborated to bind AuNPs stabilized in citrate buffer directly to a SPR surface, which is coated with bovine serum albumin (BSA) prior to binding. The formed sandwich structures are functional without additional coupling steps and provide a time‐efficient tool for rapid and sensitive detection of various biomolecules. The AuNPs are successfully loaded with streptavidin (SaV). This allows convenient immobilization of all kinds of biotinylated molecules (e.g., enzymes, antibodies, etc.). The latter strategy has the advantage to circumvent the denaturation of proteins, which is caused by close contact to gold surfaces. Limit of detection and limit of quantification are found to be in the femtomolar range.

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“…49,50 When fabrication affordability and scalability as well as optical tunability are required, block copolymer micelle nanolithography (BCMN) stands out over other methods thanks to its capability to easily produce large-scale periodic arrays of AuNPs whose lattice parameters can be modified by simply choosing the appropriate diblock copolymers. 51 In recent studies, we successfully realized two plasmonic substrates consisting of hexagonally arranged 52 (utilizing BCMN) and randomly positioned 53 AuNPs (electrostatic immobilization) apt to be implemented in a PEF-based aptaimmunoassay for detecting malaria biomarker Plasmodium falciparum lactate dehydrogenase (Pf LDH) in human whole blood down to femtomolar and picomolar levels, respectively, without any sample preconcentration and pretreatment.…”

Section: Introductionmentioning

confidence: 99%

Double-Resonant Nanostructured Gold Surface for Multiplexed Detection

Minopoli

Scardapane²,

Ventura³

et al. 2022

ACS Appl. Mater. Interfaces

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A novel double-resonant plasmonic substrate for fluorescence amplification in a chip-based apta-immunoassay is herein reported. The amplification mechanism relies on plasmon-enhanced fluorescence (PEF) effect. The substrate consists of an assembly of plasmon-coupled and plasmon-uncoupled gold nanoparticles (AuNPs) immobilized onto a glass slide. Plasmon-coupled AuNPs are hexagonally arranged along branch patterns whose resonance lies in the red band (∼675 nm). Plasmon-uncoupled AuNPs are sprinkled onto the substrate, and they exhibit a narrow resonance at 524 nm. Numerical simulations of the plasmonic response of the substrate through the finite-difference time-domain (FDTD) method reveal the presence of electromagnetic hot spots mainly confined in the interparticle junctions. In order to realize a PEF-based device for potential multiplexing applications, the plasmon resonances are coupled with the emission peak of 5-carboxyfluorescein (5-FAM) fluorophore and with the excitation/emission peaks of cyanine 5 (Cy5). The substrate is implemented in a malaria apta-immunoassay to detect Plasmodium falciparum lactate dehydrogenase (PfLDH) in human whole blood. Antibodies against Plasmodium biomarkers constitute the capture layer, whereas fluorescently labeled aptamers recognizing PfLDH are adopted as the top layer. The fluorescence emitted by 5-FAM and Cy5 fluorophores are linearly correlated (logarithm scale) to the PfLDH concentration over five decades. The limits of detection are 50 pM (1.6 ng/mL) with the 5-FAM probe and 260 fM (8.6 pg./mL) with the Cy5 probe. No sample preconcentration and complex pretreatments are required. Average fluorescence amplifications of 160 and 4500 are measured in the 5-FAM and Cy5 channel, respectively. These results are reasonably consistent with those worked out by FDTD simulations. The implementation of the proposed approach in multiwell-plate-based bioassays would lead to either signal redundancy (two dyes for a single analyte) or to a simultaneous detection of two analytes by different dyes, the latter being a key step toward high-throughput analysis.

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Randomly positioned gold nanoparticles as fluorescence enhancers in apta-immunosensor for malaria test

Cited by 22 publications

References 44 publications

Nanostructured Surfaces as Plasmonic Biosensors: A Review

Nanostructured Surfaces as Plasmonic Biosensors: A Review

Gold Albumin Sandwich Structures for Enhanced Biosensing Using Surface Plasmon Resonance

Double-Resonant Nanostructured Gold Surface for Multiplexed Detection

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