We have developed a DNA aptamer-conjugated graphene field-effect transistor (GFET) biosensor platform to detect receptor-binding domain (RBD), nucleocapsid (N), and spike (S) proteins, as well as viral particles of original Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coronavirus and its variants in saliva samples. The GFET biosensor is a label-free, rapid (≤20 min), ultrasensitive handheld wireless readout device. The limit of detection (LoD) and the limit of quantitation (LoQ) of the sensor are 1.28 and 3.89 plaque-forming units (PFU)/mL for S protein and 1.45 and 4.39 PFU/mL for N protein, respectively. Cognate spike proteins of major variants of concern (N501Y, D614G, Y453F, Omicron-B1.1.529) showed sensor response ≥40 mV from the control (aptamer alone) for fM to nM concentration range. The sensor response was significantly lower for viral particles and cognate proteins of Middle East Respiratory Syndrome (MERS) compared to SARS-CoV-2, indicating the specificity of the diagnostic platform for SARS-CoV-2 vs. MERS viral proteins. During the early phase of the pandemic, the GFET sensor response agreed with RT-PCR data for oral human samples, as determined by the negative percent agreement (NPA) and positive percent agreement (PPA). During the recent Delta/Omicron wave, the GFET sensor also reliably distinguished positive and negative clinical saliva samples. Although the sensitivity is lower during the later pandemic phase, the GFET-defined positivity rate is in statistically close alignment with the epidemiological population-scale data. Thus, the aptamer-based GFET biosensor has a high level of precision in clinically and epidemiologically significant SARS-CoV-2 variant detection. This universal pathogen-sensing platform is amenable for a broad range of public health applications and real-time environmental monitoring.

中文翻译：

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利用便携式无线石墨烯生物传感器对唾液中未经处理的 SARS-CoV-2 病毒及其变种进行快速自检

我们开发了DNA适体缀合的石墨烯场效应晶体管（GFET）生物传感器平台，用于检测受体结合域（RBD）、核衣壳（N）和刺突（S）蛋白，以及原始严重急性呼吸道病毒颗粒唾液样本中的综合征冠状病毒 2 (SARS-CoV-2) 冠状病毒及其变种。GFET 生物传感器是一种无标记、快速（≤20 分钟）、超灵敏手持式无线读出设备。传感器的检测限 (LoD) 和定量限 (LoQ) 分别为 S 蛋白的 1.28 和 3.89 噬菌斑形成单位 (PFU)/mL，N 蛋白的检测限 (LoD) 和定量限 (LoQ) 分别为 1.45 和 4.39 PFU/mL。关注的主要变体（N501Y、D614G、Y453F、Omicron-B1.1.529）的同源刺突蛋白显示，对于 fM 至 nM 浓度范围，传感器响应与对照（仅适配体）相比≥40 mV。与 SARS-CoV-2 相比，传感器对中东呼吸综合征 (MERS) 病毒颗粒和同源蛋白的响应明显较低，这表明 SARS-CoV-2 与 MERS 病毒蛋白诊断平台的特异性。在大流行的早期阶段，根据负一致性百分比 (NPA) 和正一致性百分比 (PPA) 确定，GFET 传感器响应与人类口腔样本的 RT-PCR 数据一致。在最近的 Delta/Omicron 浪潮中，GFET 传感器还可靠地区分了临床唾液样本的阳性和阴性。尽管在大流行后期阶段敏感性较低，但 GFET 定义的阳性率在统计上与流行病学人口规模数据密切一致。因此，基于适配体的 GFET 生物传感器在临床和流行病学意义重大的 SARS-CoV-2 变异检测中具有高精度。这种通用病原体传感平台适用于广泛的公共卫生应用和实时环境监测。