The need for new and innovative point of care (POC) systems providing a feasible alternative to costly and time consuming standard laboratory techniques is becoming more evident every day, particularly in the case of cardiovascular diseases. Coupling optical and electrochemical principles for highly specific and sensitive detection of biomarkers could boost the successful implementation of POC systems in biomedical environments. We suggest indium tin oxide (ITO) as a promising material for working electrodes in optoelectrochemical sensors, owing to the rare combination of high electrical conductivity and optical transparency it presents. Moreover, the nanostructured nature of the electrodes' surface is crucial for an eventual miniaturization of the POC system. In this work, we describe the construction and characterization of a nanostructured ITO electrode modified with aryl diazonium salt as transparent substrate for electrochemical immunosensors. The developed electrode was tested for the detection of tumour necrosis factor α (TNF-α), a cardiac biomarker playing an important role in the prevention of heart failure. Macro and microscopic evidences (gathered from electrochemical and spectral techniques) of covalent bonding and high surface coverage are provided. Specific interaction between antigen (TNF-α) and monoclonal antibody (Ab-TNF-α) was verified by fluorescence patterning, confirming the proper bio-recognition of the cytokine. As a proof-of-concept, results of electrochemical impedance spectroscopy (EIS) show stabilized semi-quantitative label-free detection of TNF-α at several concentrations (from 10 pg/mL to 100 pg/mL). These preliminary results demonstrate the feasibility of using transparent substrates for the detection of cytokines at low concentrations, and the consequent application in POC systems for the monitoring of cardiovascular diseases.

每天对于新的和创新的即时医疗（POC）系统的需求日益迫切，这需要昂贵且耗时的标准实验室技术，这在心血管疾病方面尤为明显。结合光学和电化学原理进行生物标志物的高特异性和灵敏检测可以促进POC系统在生物医学环境中的成功实施。我们建议将铟锡氧化物（ITO）用作光电化学传感器中工作电极的有前途的材料，因为它具有高导电性和光学透明性的罕见组合。此外，电极表面的纳米结构性质对于最终实现POC系统的小型化至关重要。在这项工作中，我们描述了用芳基重氮盐修饰的纳米结构ITO电极的构建和表征，该电极用作电化学免疫传感器的透明基材。测试了开发的电极以检测肿瘤坏死因子α（TNF-α），这是一种在预防心力衰竭中起重要作用的心脏生物标志物。提供了共价键合和高表面覆盖率的宏观和微观证据（从电化学和光谱技术中收集）。抗原（TNF-α）和单克隆抗体（Ab-TNF-α）之间的特异性相互作用通过荧光图谱进行了验证，从而证实了细胞因子的正确生物识别。作为概念证明，电化学阻抗谱（EIS）的结果表明，几种浓度（从10 pg / mL到100 pg / mL）的TNF-α均能稳定地进行半定量无标记检测。这些初步结果证明了使用透明底物检测低浓度细胞因子的可行性，并因此在POC系统中用于监测心血管疾病。