Department of Biomedical Engineering, National Cheng Kung University, Taiwan; Medical Device Innovation Center, National Cheng Kung University, Taiwan.
Department of Biomedical Engineering, National Cheng Kung University, Taiwan.
Biosens Bioelectron. 2018 Mar 15;101:75-83. doi: 10.1016/j.bios.2017.10.002. Epub 2017 Oct 11.
Diffusometry is sensitive to geometric changes of particles. Target antigens can be detected through diffusivity changes resulting from their immunoreactions by functionalizing particle surface with a specific antibody. Considering that Brownian motion is a self-driven phenomenon, diffusometric immunosensing features several characteristics, such as no-washing steps, rapid detection, high flexibility, and high sensitivity. Until recently, this technique has been applied to many biomedical fields, such as monitoring of microorganism motility and diagnosis of diseases with biomarkers. Despite the abovementioned advantages, diffusivity changes in conventional diffusometry can be compromised at low-abundance antigens because proteins are much smaller than capture particles. To overcome such restriction, we present an improved diffusometric immunosensing technique by grafting additional gold nanoparticles (AuNPs) to capture particles to enhance size changes. A diabetic retinopathy (DR) biomarker, tumor necrosis factor-α was selected to evaluate the proposed immunosensing technique. Spherical AuNPs showed better enhancement than rod-like AuNPs during measurement. Limit of detection was improved by at least 100-fold down to 10pg/mL. A dichotomous method was also developed to enable rapid detection and avoid tedious calibration. The relationship of concentrations between the two solutions used can be explicitly determined by comparing diffusivity of an unknown concentration of target molecules with that of a reference solution. Minimum discernible concentration reached as low as twofold higher or lower than basal concentration. Tear samples were collected from four volunteers, including three healthy subjects and one proliferative DR patient to prove the concept in diagnosis of the disease. All data showed good agreement with preset conditions. The technique eventually provides an insight into rapid diagnoses of diseases in the early stage.
扩散谱法对粒子的几何形状变化很敏感。通过在粒子表面功能化特定抗体，可以检测到靶抗原，因为它们的免疫反应会导致扩散率发生变化。考虑到布朗运动是一种自驱动现象，扩散谱免疫传感具有几个特点，如无需洗涤步骤、快速检测、高灵活性和高灵敏度。直到最近，这项技术已应用于许多生物医学领域，例如监测微生物的运动和用生物标志物诊断疾病。尽管有上述优势，但在低丰度抗原时，常规扩散谱法的扩散率变化可能会受到影响，因为蛋白质比捕获粒子小得多。为了克服这种限制，我们提出了一种改进的扩散谱免疫传感技术，通过在捕获粒子上嫁接额外的金纳米粒子（AuNPs）来增强尺寸变化。选择糖尿病视网膜病变（DR）生物标志物肿瘤坏死因子-α来评估所提出的免疫传感技术。在测量过程中，球形 AuNPs 比棒状 AuNPs 显示出更好的增强效果。检测限至少提高了 100 倍，降至 10pg/mL。还开发了一种二分法来实现快速检测并避免繁琐的校准。通过将目标分子的未知浓度与参考溶液的扩散率进行比较，可以明确确定两种溶液之间浓度关系。最小可分辨浓度低至基础浓度的两倍以上或以下。从四名志愿者中收集了眼泪样本，包括三名健康受试者和一名增殖性 DR 患者，以证明该技术在疾病诊断中的概念。所有数据均与预设条件吻合良好。该技术最终为疾病的早期快速诊断提供了一个思路。
