Development of an Enzymatic Organic Electrochemical Transistor for Studying Cerebral Cholesterol Metabolism in Alzheimer's Pathology

阿尔茨海默病(AD)影响着全球超过5000万人，预计到2050年，受影响的人数将增加三倍。AD是最常见的痴呆症，会导致大脑中神经元的进行性下降，从而导致记忆障碍、语言和解决问题的能力下降。最近的研究表明，脑内胆固醇代谢异常与AD的发病有直接关系。此外，AD患者脑脊液中胆固醇代谢也发生了显著变化。然而，目前用于分析脑脊液胆固醇的实验室方法对实验构成了限制，因为它们复杂、昂贵且耗时。因此，在本博士项目中，提出了一种从脑脊液中测量脑胆固醇的新方法。有机聚合物电化学晶体管(OECTS)将被用作POC生物传感器，其性能优于目前的临床检测方法。这将为研究脑脊液中的胆固醇是否可以作为AD的早期生物标志物提供一种快速、方便和可靠的体外方法。该项目的第一个目标是设计和制造一种体外生物传感器，以研究胆固醇代谢在AD在大脑中传播中的作用。这将通过处理不同脑胆固醇浓度的细胞培养和样本并使用高分辨率成像来研究胆固醇代谢对AD生物标记物的影响来实现。该项目的第二个目标是将OECT生物传感器开发成一种护理点设备，该设备可以在就医时可靠地监测脑脊液样本中的脑胆固醇浓度，帮助患者在早期阶段认识到患上AD的风险。为此，制造的有机电化学晶体管将使用氧化还原酶进行生物功能化，这种酶专用于大脑胆固醇，长期使用是安全和可靠的。在本项目中，将通过层沉积、光刻、刻蚀和旋涂等工艺来制备具有聚(3，4-乙二氧基噻吩基)聚苯乙烯磺酸盐(PEDOT：PSS)通道的OOES。PEDOT：PSS是最有前景的生物电子材料之一，因为它结合了离子和电子电荷，导致了巨大的信号放大，性能超过了大多数晶体管。此外，它在水介质中非常稳定，非常适合于脑脊液中胆固醇的检测。将研究使用不同的胆固醇氧化酶(包括纳米颗粒和人工介体)对闸门进行生物功能化的技术，以实现最佳响应时间和高选择性。然后使用脑脊液样本来检验OECTS的准确性。最后，它们将被应用于实时实验，以研究AD的病理与脑胆固醇之间的相关性。因此，OOTS具有巨大的POC潜力，可以解决当前复杂和耗时的脑脊液胆固醇定量临床方法带来的挑战。因此，在该项目结束时，将生产一种用于测量脑脊液胆固醇的新型生物传感器，与传感器和仪器的战略相一致，以结合新的先进设备，为未来提供更好的医疗保健和诊断。该项目的实施将基于医疗保健领域微电子设备技术的知识和想法，因为它采用了采用新技术和材料(如PEDOT：PSS有机聚合物和纳米颗粒)的OECTS微电子设备的低功耗设计。该项目的愿景完全符合临床技术研究领域的想法，因为它专注于开发一种用于AD诊断和监测的新型POC设备，从而通过提出一种新颖、可靠和快速的传感技术来改善健康和护理。

Alzheimer's disease (AD) affects more than 50 million people worldwide and is expected to affect three times more people by 2050. AD is the most common form of dementia and causes progressive decline of neurons in the brain, which leads to memory impairment, decline in language and problem-solving skills. Recent studies show that dysfunction in cerebral cholesterol metabolism is directly linked to AD pathogenesis. Moreover, there is a significant change in cholesterol metabolism in the cerebral spinal fluid (CSF) of AD's patients. However, the current laboratory methods used for analysis of CSF cholesterol impose limitations to experiments because they are complex, expensive, and time-consuming. Therefore, in this PhD project, a novel method for measuring cerebral cholesterol from CSF is proposed. Organic polymer electrochemical transistors (OECTs) will be used as point-of-care (POC) biosensors, which can outperform current clinical detection methods. This will offer a fast, easily accessible, and reliable in-vitro method to study whether cholesterol in CSF can act as an early biomarker of AD. The first aim of the project is to design and fabricate an in-vitro biosensor to investigate the role of cholesterol's metabolism in the spread of AD in the brain. This will be achieved through treating cell cultures and samples with different cerebral cholesterol concentrations and using high resolution imaging to investigate the effect of cholesterol metabolism on AD's biomarkers. The second aim of the project is to develop the OECT biosensor into a point-of-care device, which can perform reliable monitoring of the cerebral cholesterol's concentration from CSF sample at the time of the medical consultation to help patients recognise the risk of developing AD at the early stages. For this purpose, the fabricated organic electrochemical transistors will be biofunctionalised with redox enzymes that are specific for cerebral cholesterol and are safe and reliable for long-term use. In this project, OECTs with a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) channel will be fabricated by processes such as layer deposition, lithography, etching, and spin-coating. PEDOT:PSS is one of the most promising bioelectronics materials due to its combined ionic and electronic charge, leading to huge signal amplification, outperforming most transistors. Moreover, it is very stable in aqueous media, which makes it very suitable for detection of cholesterol in CSF. Techniques for biofunctionalising the gate with different cholesterol oxidases including nanoparticles and artificial mediators will be investigated for achieving optimum response time and high selectivity. Then the accuracy of the OECTs will be tested by using CSF samples. Finally, they will be applied in real-time experiments to investigate the correlation between AD's pathology and cerebral cholesterol. Thus, OECTs hold a great potential for POC, which can address the challenges imposed by the current complex and time-consuming clinical methods for quantifying CSF cholesterol. Thus, at the end of this project, a novel biosensor for measuring CSF cholesterol will be produced, aligning with the strategies of sensors and instrumentation to incorporate a new advanced device to provide a future with better healthcare and diagnosis. The implementation of the project will be based on knowledge and ideas from microelectronic device technology in healthcare since it incorporates a low-power design of the OECTs microelectronic devices by novel technologies and materials such as the PEDOT:PSS organic polymer and nanoparticles. The vision of this project aligns fully with the ideas from clinical technologies research area since it focuses on developing a novel POC device for diagnosis and monitoring of AD and thus improves health and care by proposing a novel, reliable and fast sensing technology.