RAPID: Fast Holographic Assay for Viral Infection with Application to COVID-19

病毒感染的常规诊断测试集中在病原体的生化特性上;它们需要昂贵的试剂和由训练有素的人员进行的多个处理步骤。 这个RAPID程序使用快速和廉价的光学技术来检测病毒病原体的物理特性。 使这种新的医学诊断方法成为可能的突破是一种称为全息粒子表征（HPC）的技术。 HPC为特殊制备的测试珠创建激光全息图，并使用这些全息图来监测分子或病毒颗粒结合到其表面时发生的珠属性的微小变化。 HPC最初是为软凝聚态物理学的基础研究而开发的，已经被证明可以在模型系统中提供快速和灵敏的免疫测定。 这些测量快速、便宜，并且可以在最少的人为干预下自动执行。 下一步是为不同的目标疾病创建测试珠库，并证明HPC可以诊断这些疾病-首先在研究实验室，然后在临床环境中。这项工作的预期产品是一个新的诊断病毒感染的平台，可以满足快速，准确和具有成本效益的测试下所施加的公共卫生危机的压力。技术摘要有一个迫切需要新的技术来检测病毒病原体。 全息结合测定可以通过其对功能化探针珠的光学性质的影响来检测流体介质中病毒颗粒和抗体的存在。 将为该项目开发的微米级珠子将在其表面结合化学基团，以选择性地结合特定的靶点，例如导致COVID-19的SARS-CoV-2病毒或感染后产生的抗体。结合的目标增加了珠子的表观尺寸，并改变了其光散射特性。 这两种效应都可以通过全息颗粒表征直接解决，全息颗粒表征是一种相对较新的平台技术，具有以千分之一的精度测量微米级胶体球的直径和折射率的能力。 使用用于全息颗粒表征的商业仪器，可以在几分钟内完成由数千个单珠测量组成的统计样本。 不需要专门的试剂。 多个靶标的多重测定可以用功能化珠的文库进行，所述功能化珠通过它们的基部直径和折射率来区分。 因此，每种这样的测定都可以通过病毒体的存在以及抗体的存在来同时诊断病毒感染。 该RAPID计划将提供用于诊断病毒感染的探针珠的可扩展合成和用于执行全息结合测定的自动化协议，从而实现高通量医学诊断。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical AbstractConventional diagnostic tests for viral infections focus on the biochemical properties of pathogens; they require costly reagents and multiple processing steps by highly trained personnel. This RAPID program instead uses fast and inexpensive optical techniques to detectthe physical properties of viral pathogens. The breakthrough that enables this new approach to medical diagnostics is a technique called holographic particle characterization (HPC). HPC creates laser holograms of specially prepared test beads and uses those holograms to monitor small changes in the beads’ properties that occur when molecules or virus particles bind to their surfaces. Originally developed for fundamental research in soft condensed matter physics, HPC already has been demonstrated to provide fast and sensitive immunoassays in model systems. These measurements are fast, inexpensive and can be performed automatically with minimal human intervention. The next step is to create libraries of test beads for different target diseases and to demonstrate that HPC can diagnose those diseases - first in the research laboratory, and then in a clinical setting. The anticipated product of this work is a new platform for diagnosing viral infections that can meet the need for fast, accurate and cost-effective testing under the strains imposed by public health crises.Technical AbstractThere is an urgent need for new technologies to detect viral pathogens. Holographic binding assays can detect the presence of virus particles and antibodies in fluid media through their influence on the optical properties of functionalized probe beads. The micrometer-scale beads that will be developed for this program will incorporate chemical groups on their surfaces to selectively bind specific targets, such as the SARS-CoV-2 virus responsible for COVID-19 or the antibodies that are produced in response to infection. Bound targets increase the apparent size of a bead and alter its light-scattering properties. Both of these effects can be resolved directly by holographic particle characterization, a comparatively new platform technology that has the demonstrated ability to measure the diameter and refractive index of micrometer-scale colloidal spheres with part-per-thousand precision. A statistical sample consisting of thousands of single-bead measurements can be completed in a matter of minutes using commercial instrumentation for holographic particle characterization. Specialized reagents are not required. Multiplexed assays for multiple targets can be performed with libraries of functionalized beads that are distinguished by their base diameters and refractive indexes. Each such assay can therefore simultaneously diagnose a viral infection both by the presence of virions, and also by the presence of antibodies. This RAPID program will deliver scalable syntheses of probe beads for diagnosing viral infection and automated protocols for performing holographic binding assays, enabling high-throughput medical diagnostics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.