Identifying infectiousness of SARS-CoV-2 by ultra-sensitive SnS2 SERS biosensors with capillary effect

Abstract

The current COVID-19 pandemic urges us to develop ultra-sensitive surface-enhanced Raman scattering (SERS) substrates to identify the infectiousness of SARS-CoV-2 virions in actual environments. Here, a micrometer-sized spherical SnS 2 structure with the hierarchical nanostructure of "nano-canyon” morphology was developed as semiconductor-based SERS substrate, and it exhibited an extremely low limit of detection of 10 −13 M for methylene blue, which is one of the highest sensitivities among the reported pure semiconductor-based SERS substrates. Such ultra-high SERS sensitivity originated from the synergistic enhancements of the molecular enrichment caused by capillary effect and the charge transfer chemical enhancement boosted by the lattice strain and sulfur vacancies. The novel two-step SERS diagnostic route based on the ultra-sensitive SnS 2 substrate was presented to diagnose the infectiousness of SARS-CoV-2 through the identification standard of SERS signals for SARS-CoV-2 S protein and RNA, which could accurately identify non-infectious lysed SARS-CoV-2 virions in actual environments, whereas the current PCR methods cannot.

Functional Nanomaterials for Rapid Detection of SARS-CoV-2: a Review

“…1.1 新冠病毒的结构特征 新型冠状病毒 (SARS-CoV-2) ， 简称新冠病毒， 是新冠肺炎(COVID-19)的病原体，与严重急性呼 吸综合征冠状病毒 (SARS-CoV) 和中东呼吸综合征 冠状病毒(MERS-CoV)同属于 β 类冠状病毒组 [7][8][9] 。SARS-CoV-2 的基因组包含超过 29000 个碱基， 编码 29 种蛋白质 [10] 。如图 1 所示，其基因组核心 区被包裹于由核衣壳蛋白(N 蛋白) 、自身刺突蛋白 (S 蛋白) 、膜糖蛋白(M 蛋白) 、包膜蛋白(E 蛋 白)组成的结构蛋白的外围包膜中 [11] 。非结构蛋白 (NsPs)最初形成为两个长多肽，通过病毒的主要 蛋白酶 (MP)、 Nsp5 的作用， 释放 RNA 依赖性 RNA 聚合酶(RdRp，又称 Nsp12) [12] 。 1.2 SARS-CoV-2 的检测方法 SARS-CoV-2 的检测依赖于结构特征，主要针 对 SARS-CoV-2 的 RNA、N 蛋白和 S 蛋白展开。 SARS-CoV-2 的常见检测方法有荧光 PCR 法 [1,[13][14][15] 、 酶联免疫法(Enzyme Linked Immunosorbent Assay, ELISA) [16] 、 表面拉曼增强 (Surface Enhanced Raman Scattering，SERS) [17][18][19] 、电化学检测 [20][21][22] 等。 图 1 SARS-CoV-2 的结构 Fig. 1 The structure of SARS-CoV-2 荧光 PCR 法 的目标分子为病毒的 遗传物质 RNA，通过逆转录将 RNA 转变为互补 DNA，并经 过扩增后再检测。同时以病毒 ORFIab 基因和核衣 壳蛋白 N 基因中的保守序列为靶标，设计特异性引 物和荧光探针 [1,[13][14][15] 。 当靶标特异性探针与靶序列杂 交时，探针中的标记荧光团会被 DNA 聚合酶的核 酸外切酶裂解，产生荧光信号。荧光 PCR 测定法具 有一定的灵敏度和超高的特异性，但其操作复杂、 耗时且需要专业人员处理和运输样本。 血清学检测 [23][24][25] 主要依赖于抗原抗体的特异性 结合，分为基于抗原的检测和基于抗体的检测。前 者主要针对感染前期进入人体的 SARS-CoV-2 表面 地与目标分析物(细菌、病毒)反应并产生电信号 [26][27][28] 。根据电化学接收信号的不同，依次分为伏安 法、电位法、阻抗法、基于场效应晶体管的生物传 感器法 [29] 。…”

Visualized SERS Imaging of Single Molecule by Ag/Black Phosphorus Nanosheets

“…Surface-enhanced Raman scattering (SERS) is a powerful tool to detect the spectral signals of molecules even at the single-molecular level [ 10 – 13 ]. It is widely used in biochemical analysis, such as pesticide residue analysis, virus detection, tissue tumor recognition, and even bioimaging due to its high sensitivity and molecular specificity [ 14 – 18 ]. However, there are still two obstacles: the fabrication of ultra-sensitive SERS substrates and the detection of single molecule (SM) over the surface of nanostructures, i.e., to achieve a single-molecule SERS-imaging [ 19 – 23 ].…”

Potentiometric Biosensors Based on Molecular-Imprinted Self-Assembled Monolayer Films for Rapid Detection of Influenza A Virus and SARS-CoV-2 Spike Protein

“…Recent reports also demonstrated the detection of SARS-CoV-2 via surface-enhanced Raman scattering (SERS) using functionalized conductive nanostructures, which is highly sensitive and prompt but requires an elaborate experimental detection. 5 − 7 …”