Electrochemical affinity biosensors have the potential to facilitate the development of multiplexed point-of-care diagnostics in complex biological fluids. However, their commercial viability has been hindered by challenges such as electrode biofouling and the lack of inherent redox properties. To address this unmet need, we have developed a universal nanocomposite coating which is unique in its ability to not only allow oriented conjugation of the biorecognition element but also specific detection directly in complex biological fluids like serum and urine owing to its built-in antifouling and redox capabilities, thus improving suitability for point of care testing. This multifunctional coating comprises a 3D porous crosslinked bovine serum albumin matrix for oriented conjugation and antifouling properties with embedded graphene nanosheets modified with amino–ferrocene for enhanced conductivity and mediator-free biosensing. The coating showed minimal signal degradation despite prolonged exposure to 1% bovine serum albumin, artificial urine and untreated human serum for up to 30 days. To demonstrate its utility, we fabricated and tested proof-of-concept electrochemical immunosensors for bladder cancer protein biomarkers, specifically interleukin-8 (IL-8) and vascular endothelial growth factor (VEGF). The practical feasibility was highlighted by the excellent sensitivity and specificity observed for IL-8 and VEGF with a limit of detection of 41 pg mL⁻¹ and 67 pg mL⁻¹, respectively. Consequently, this universal nanocomposite-based electrochemical biosensing platform can be extended to the point of care testing of a broad spectrum of biomarkers present in complex biological fluids, thus enabling reliable and early diagnostics.

中文翻译：

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具有防污和氧化还原功能的通用纳米复合涂层，用于复杂生物流体中的电化学亲和生物传感

电化学亲和生物传感器有潜力促进复杂生物液体中多重即时诊断的发展。然而，它们的商业可行性受到电极生物污垢和缺乏固有氧化还原特性等挑战的阻碍。为了解决这一未满足的需求，我们开发了一种通用纳米复合涂层，其独特之处在于，由于其内置的防污和防污功能，不仅可以定向结合生物识别元件，还可以直接在血清和尿液等复杂生物液体中进行特异性检测。氧化还原能力，从而提高即时测试的适用性。这种多功能涂层包含 3D 多孔交联牛血清白蛋白基质，具有定向缀合和防污特性，并嵌入氨基二茂铁修饰的石墨烯纳米片，以增强导电性和无介质生物传感。尽管长时间暴露于 1% 牛血清白蛋白、人造尿液和未经处理的人血清长达 30 天，但该涂层显示出最小的信号衰减。为了证明其实用性，我们制造并测试了膀胱癌蛋白质生物标志物的概念验证电化学免疫传感器，特别是白介素 8 (IL-8) 和血管内皮生长因子 (VEGF)。IL-8和VEGF的优异灵敏度和特异性突出了实际可行性，检测限分别为41 pg mL ^-1和67 pg mL ^-1。因此，这种基于纳米复合材料的通用电化学生物传感平台可以扩展到复杂生物液体中存在的广泛生物标志物的即时检测，从而实现可靠的早期诊断。