<b>Printed photonic crystal biochips for rapid and sensitive detection of biomarkers in various body fluids</b>

There is an urgent requirement to improve accessibility to diagnostic tools in remote areas. This requires assays that are easy to use, cost effective, and produce rapid results. It is important in the field of modern medicine and public health, such as early disease diagnosis, real-time monitoring, epidemic control, medical cost control and other aspects. In this protocol, an all-printed photonic crystal (PC) biochip is developed for point-of-care testing of biomarkers. We detail the fabrication of photonic crystal biochips self-assembled from latex nanospheres based on fluorescence signal analysis to achieve large-scale printing, biofunctionalization and biomarker detection. The PC biochip allows for the simultaneous detection of multiple biomarkers. We demonstrate this by detailing an example procedure to prepare a chip that can be used to detect three inflammatory biomarkers in 10 minutes at low sample volumes at a cost of less than 3 CNY (~0.41 USD) per PC co-detection biochip. The PC biochip can be applied to the detection of a majority of biomarkers and used for diagnosis in clinical samples as a universal detection platform. The PC microarrays allow for mass-printed preparation, which can be printed at up to 2700 pieces per hour by one printer, and can be stored for a long time (&gt;6 months) after heating. The biofunctionalization process including capture antibody coupling and blocking takes 3-4 hours and the detection process takes 20 minutes.提升偏远地区诊断工具可及性的需求十分迫切。为满足该需求，亟需开发操作简便、高性价比且能快速出具结果的检测方法。此类检测在现代医学与公共卫生领域具有重要应用价值，可覆盖疾病早期诊断、实时监测、疫情防控以及医疗成本管控等诸多场景。本研究方案开发了一款全印刷光子晶体（photonic crystal, PC）生物芯片，用于生物标志物的即时检测。我们详细阐述了基于荧光信号分析、由乳胶纳米球自组装而成的光子晶体生物芯片制备流程，可实现大规模印刷、生物功能化修饰与生物标志物检测。该光子晶体生物芯片可实现多种生物标志物的同步检测。我们通过详细介绍一款芯片的制备示例验证了该性能：该芯片可在10分钟内以低样本量检测三种炎症标志物，每块光子晶体联合检测生物芯片的成本低于3元人民币（约合0.41美元）。该光子晶体生物芯片可适配绝大多数生物标志物的检测，可作为通用检测平台应用于临床样本的疾病诊断。该光子晶体微阵列可实现批量印刷制备，单台打印机每小时最高可印刷2700片芯片，经加热处理后可长期储存（>6个月）。包括捕获抗体偶联与封闭步骤在内的生物功能化修饰流程耗时3至4小时，检测流程耗时20分钟。