We present a sensitive and low-cost immunoassay, based on a customized open-source quartz crystal microbalance coupled with graphene biointerface sensors (G-QCM), to quantify antibodies in undiluted patient serum. We demonstrate its efficacy for a specific antibody against the phospholipase A2 receptor (anti-PLA2R), which is a biomarker in primary membranous nephropathy. A novel graphene–protein biointerface was constructed by adsorbing a low concentration of denatured bovine serum albumin (dBSA) on the reduced graphene oxide (rGO) sensor surface. The dBSA film prevents the denaturation of the protein receptor on the rGO surface and serves as the cross-linker for immobilization of the receptor for anti-PLA2R antibodies on the surface. The detection limit and selectivity of this G-QCM biosensor was compared with a commercial QCM system. The G-QCM immunoassay exhibited good specificity and high sensitivity toward the target, with an order of magnitude better detection limit (of 100 ng/mL) compared to the commercial system, at a fraction of the cost and with considerable time saving. The results obtained from patient sera compared favorably with those from enzyme-linked immunosorbent assay, validating the feasibility of use in clinical applications. The multifunctional dBSA-rGO platform provides a promising biofunctionalization method for universal immunoassay and biosensors. With the advantages of inexpensive, rapid, and sensitive detection, the G-QCM sensor and instrument form an effective autoimmune disease screening tool.

中文翻译：

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基于带有石墨烯生物界面的石英晶体微天平的护理点免疫传感器用于抗体测定

我们基于定制的开源石英晶体微量天平，结合石墨烯生物界面传感器（G-QCM），提供了一种灵敏且低成本的免疫测定方法，以定量未稀释患者血清中的抗体。我们证明了其针对磷脂酶A2受体（抗PLA2R）的特异性抗体的功效，该抗体是原发性膜性肾病的生物标志物。通过在还原的氧化石墨烯（rGO）传感器表面上吸附低浓度的变性牛血清白蛋白（dBSA），构建了一种新型的石墨烯-蛋白质生物界面。dBSA膜可防止rGO表面上蛋白质受体的变性，并用作将抗PLA2R抗体受体固定在表面上的交联剂。将该G-QCM生物传感器的检测限和选择性与商用QCM系统进行了比较。与商业系统相比，G-QCM免疫测定法对靶标表现出良好的特异性和高灵敏度，检测限（100 ng / mL）好几个数量级，而成本却很小，并且节省了大量时间。从患者血清获得的结果与酶联免疫吸附测定的结果相比具有优势，证实了其在临床应用中的可行性。多功能dBSA-rGO平台为通用免疫测定和生物传感器提供了一种有前途的生物功能化方法。G-QCM传感器和仪器具有价格低廉，快速且灵敏的检测优势，是一种有效的自身免疫性疾病筛查工具。与商业系统相比，检出限（100 ng / mL）更好一个数量级，而成本却很小，并且节省了大量时间。从患者血清获得的结果与酶联免疫吸附测定的结果相比具有优势，证实了其在临床应用中的可行性。多功能dBSA-rGO平台为通用免疫测定和生物传感器提供了一种有前途的生物功能化方法。G-QCM传感器和仪器具有价格低廉，快速且灵敏的检测优势，是一种有效的自身免疫性疾病筛查工具。与商业系统相比，检出限（100 ng / mL）更好一个数量级，而成本却很小，并且节省了大量时间。从患者血清获得的结果与酶联免疫吸附测定的结果相比具有优势，证实了其在临床应用中的可行性。多功能dBSA-rGO平台为通用免疫测定和生物传感器提供了一种有前途的生物功能化方法。G-QCM传感器和仪器具有价格低廉，快速且灵敏的检测优势，是一种有效的自身免疫性疾病筛查工具。多功能dBSA-rGO平台为通用免疫测定和生物传感器提供了一种有前途的生物功能化方法。G-QCM传感器和仪器具有价格低廉，快速且灵敏的检测优势，是一种有效的自身免疫性疾病筛查工具。多功能dBSA-rGO平台为通用免疫测定和生物传感器提供了一种有前途的生物功能化方法。G-QCM传感器和仪器具有价格低廉，快速且灵敏的检测优势，是一种有效的自身免疫性疾病筛查工具。