A CRISPR/Cas12a-empowered surface plasmon resonance platform for rapid and specific diagnosis of the Omicron variant of SARS-CoV-2

Abstract

The outbreak of the COVID-19 pandemic is partially due to the challenge of identifying asymptomatic and pre-symptomatic carriers of the virus, and thus highlights a strong motivation for diagnostics that can be rapidly deployed with high sensitivity. On the other hand, several concerned SARS-CoV-2 variants, including the Omicron, are required to be identified as soon as the samples are identified as ‘positive’. Unfortunately, a traditional PCR test does not allow their specific identification. Herein, for the first time, we have developed MOPCS (Methodologies of Photonic CRISPR Sensing), which combines an optical sensing technology-surface plasmon resonance (SPR), and the ‘gene scissors’ CRISPR technique to achieve both high sensitivity and specificity of viral variants’ measurement. MOPCS is a low-cost, CRISPR/Cas12a system-empowered SPR gene detecting platform that can analyze viral RNA, without the need for amplification, within 38 min from sample input to results output, and achieve a limit of detection of 15 fM. MOPCS achieves a highly sensitive analysis of SARS-CoV-2 and mutations appear in variants B.1.617.2 (Delta), B.1.1.529 (Omicron), and BA.1 (a subtype of Omicron). This platform was also used to analyze some recently collected patient samples from a local outbreak in China and identified by the Centers for Disease Control and Prevention. This innovative CRISPR-empowered SPR platform will further contribute to various fast, sensitive, and accurate detection of target nucleic acid sequences with single-base mutations.

The adjacent effect between Gd(iii) and Cu(ii) in layered double hydroxide nanoparticles synergistically enhancesT1-weighted magnetic resonance imaging contrast

“…Magnetic resonance imaging (MRI), a technique with a superior spatial resolution and contrast, has been extensively applied in clinical diagnosis without using harmful high-energy radiation. 1–5 The physical principles of MRI rely on the amount of water molecules in the examined area and finally the measurements show the spatial distribution of the relaxation of water protons. 6 Hence, effective MRI contrast agents must accelerate proton relaxation processes to shorten the T 1 (spin–lattice)/ T 2 (spin–spin) relaxation time and result in brighter/darker signals of the target tissues than the background.…”

A mid-infrared focusing grating coupler with a single circular arc element based on germanium on silicon

“…In 2020, Xue et al reported a bismuthene-enabled fluorescence quenching biosensor to detect microRNA, which is relevant to the fields of biosensors and medicine [ 18 ]. In 2022, Chen et al demonstrated a methodology of photonic clustered regularly interspaced short palindromic repeat (CRISPR) sensing for rapid and specific diagnosis of the Omicron variant of SARS-CoV-2 [ 19 ]. This innovative CRISPR-empowered surface plasmon resonance platform will further contribute to the field of biomedical sensors.…”

CRISPR techniques and potential for the detection and discrimination of SARS-CoV-2 variants of concern

“…In comparison with the results of the DNA sequencing, this assay achieved 83.3–100% positive prediction and 85.7–100% negative prediction. The approach of selecting mutations located in the PAM-proximal region has also been exploited to develop other assays for the differentiation and detection of SARS-CoV-2 and its variants [ 102 , [137] , [138] , [139] , [140] ]. In these assays, CRISPR-Cas12a-mediated detection was incorporated with other isothermal amplification techniques such as recombinase polymerase amplification (RPA), loop-mediated isothermal amplification (LAMP) and with various detection methods such as the surface plasmon resonance (SPR) and LED light-based visual/cellphone detection [ 102 , [137] , [138] , [139] , [140] ].…”