Upconversion Luminescence Sandwich Assay For Detection of Influenza H7 Subtype

Abstract

Those sensors increase the limits of detection (LOD) by using signal amplifiers but the hybridization times are usually long. [7] On the other hand, colorimetric sensor produce visible color changes upon the presence of the virus genes. The simplicity in design and readout of these sensors had attracted substantial attention. Gold nanoparticles (AuNPs) are one of the promising candidates for such detection strategy because of their high extinction coefficient and aggregation-dependent color change. [8,9] Despite the advantages, AuNPs are surface-sensitive and may induce undesired aggregations due to high ionic strength and concentration of ions, resulting in false-positive signals.Apart from those approaches, optical detection has drawn substantial attention because of their simplicity, sensitiveness, and multiplexity. [10,11] It is the fact that organic dyes are widely used in conventional qPCR assays via downconversion processes. [4,12,13] However, the dyes demonstrate undesirable emissive properties such as poor photostability, broad emission band, and small Stokes shift. [14] Therefore, they were usually employed as quenchers in nanoparticle-based detection systems. [15][16][17] High energy excited quantum dots (QDs) are another representative fluorophores in downconverting assays. [18][19][20] The excitation may induce background fluorescence and broad emission peaks, contributing to severe cross-talking problem. To address these limitations, nearinfrared (NIR) triggered upconversion luminescence (UCL) in lanthanide-doped upconversion nanoparticles (UCNPs) is very promising in biodetection. They not only display large anti-Stokes shift [21,22] but also pose minimal damage to the gene oligos. In addition, the long-lived UCL signal is easily distinguished from the short-lived background signal. As a result, UCNPs were used to detect different oligos and analytes. [23][24][25][26][27][28] The assays involved highly distance-dependent luminescence resonance energy transfer (LRET) between energy donor and acceptor, in which the luminescent intensity changes with the separation between the energy pair. [29] In this work, green emitting UCNPs and AuNPs are selected as the LRET pair owing to their well-matched emission and extinction spectrum, while AuNPs exhibit excellent extinction coefficient and photostability. The size of the nanoparticles played important roles in hybridization [30] because AuNPs demonstrate sizedependent absorption property and it can alter the stability of the hybridized DNA duplex. In addition, the size ratios of the UCNPs and AuNPs affect the formation of UCNPs-AuNPs hybrid structures. Taking advantages of 808 nm excitation of With large anti-Stokes shifts and background-free signals, upconversion luminescent (UCL) screening assays have been a promising method to reduce the transmission of influenza epidemic, which can critically alleviate the disease burden and extra annual deaths. In this work, a luminescent resonance energy transfer sandwich assay is developed, which utilizes core-shell...

Rapid and ultrasensitive detection of SARS-CoV-2 spike protein based on upconversion luminescence biosensor for COVID-19 point-of-care diagnostics

“…These main peaks are attributed to blue, red and NIR emissions, which correspond well to the absorption spectra of AuNRs ( Figure 1 d). In addition, there is a negligible decrease in upconversion luminescence (UCL) after the removal of PEI ligand (Figure S5), which is superior to the similar operation on OA-UCNPs [32] .

Figure 1 Characterization of NaYF 4 :Yb/Tm and AuNRs.

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Multiplexed detection of SARS-CoV-2 based on upconversion luminescence nanoprobe/MXene biosensing platform for COVID-19 point-of-care diagnostics

“… [22] Its large surface area facilitates multiple-donor–single-acceptor configurations and broad absorption endows it high luminescence quenching ability, which makes it favorable for developing the FRET-based biosensor applicable to multiplexed detection. [23] , [24] …”

Photoluminescent Nanoparticles for Chemical and Biological Analysis and Imaging

“…A potential disadvantage in this context is that UCNPs are often larger than the ∼10 nm range of FRET. Energy transfer efficiencies are thus highest for emitters at the surface of the NP host and potentially negligible for emitters at the center. − One strategy for mitigating this challenge has been the use of Au NPs − and nanosheets , as more efficient energy acceptors. In one recent example, Au NPs and UCNPs were the corners of a DNA tetrahedron, where the Au NPs quenched the UCNP PL via energy transfer .…”

“…A miRNA target was detected at levels as low as 0.12 fmol in live cells . Other recent studies have also used energy-transfer-based quenching and recovery with Au NPs for the detection of nucleic acids. − There are also recent examples of the use of organic dyes, metal complexes, QDs, and Ag NCs in combination with UCNPs for the energy-transfer-based detection of various analytes.…”