M Divagar, Bandaru Ramakrishna, Janakiraman Vani, Sai V V R
Department of Biotechnology, Indian Institute of Technology Madras, Chennai, 600036, India; Biomedical Engineering Division, Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai, 600036, India.
Biomedical Engineering Division, Department of Applied Mechanics, Indian Institute of Technology Madras, Chennai, 600036, India; Current Affiliation: SRM Institute of Science and Technology, Tankular, Chennai, 603203, India.
Biosens Bioelectron. 2020 Nov 1;167:112488. doi: 10.1016/j.bios.2020.112488. Epub 2020 Jul 31.
Tuberculosis (TB) is a resurgent infectious disease affecting a large number of people in the developing countries. An on-site, affordable diagnostic screening at an early-stage for an immediate anti-TB treatment is known to tremendously minimize the high mortality rates. Lipoarabinomannan (LAM), a surface glycolipid, has been identified as a potential TB biomarker present in urine at ultra-low concentrations of a few fg/mL. Here, we report a plasmonic fiber optic absorbance biosensor (P-FAB) strategy for mannosylated LAM (Man-LAM or Mtb LAM) detection down to attomolar concentrations. It involves a plasmonic sandwich immunoassay on a U-bent fiber optic probe with gold plasmonic (AuNP) labels functionalized with anti-Mtb LAM immunoglobulin M (IgM) and anti-Mtb LAM IgG respectively. The Mtb LAM is quantified in terms of absorption of light passing through the fiber probe using a green LED and a photodetector. The choice of fiber optic probes (fused silica versus polymer), the optimum size (20, 40, 60 and 80 nm) and concentration (2 × , 10 × , and 20 × ) of AuNP labels were investigated to obtain high sensitivity and lower limits of analyte detection (LoD). P-FAB with a simple LED-photodetector pair, 200 μm fused silica U-bent fiber probe and 60 nm (20 × ) AuNP labels gave LoDs down to 1 fg/mL and 10 fg/mL in the buffer and synthetic urine respectively. Moreover, the anti-Mtb LAM IgM bound sensor probes and the AuNP reagent stored at 4 °C were stable up to 45 days. P-FAB based Mtb LAM sensor demonstrates its potential for an on-site TB diagnosis.
结核病（TB）是一种在发展中国家影响大量人群的复发性传染病。已知在早期进行现场可负担得起的诊断筛查以立即进行抗结核治疗，能极大地降低高死亡率。脂阿拉伯甘露聚糖（LAM）是一种表面糖脂，已被确定为尿液中存在的一种潜在结核生物标志物，其浓度极低，仅为几飞克/毫升。在此，我们报告了一种用于检测甘露糖基化LAM（Man-LAM或结核分枝杆菌LAM）至阿托摩尔浓度的等离子体光纤吸光生物传感器（P-FAB）策略。它涉及在一个U形光纤探针上进行等离子体夹心免疫测定，该探针分别用抗结核分枝杆菌LAM免疫球蛋白M（IgM）和抗结核分枝杆菌LAM IgG功能化的金等离子体（AuNP）标记物。通过使用绿色发光二极管和光电探测器，根据穿过光纤探针的光吸收来对结核分枝杆菌LAM进行定量。研究了光纤探针（熔融石英与聚合物）的选择、AuNP标记物的最佳尺寸（20、40、60和80纳米）和浓度（2×、10×和20×），以获得高灵敏度和较低的分析物检测限（LoD）。采用简单的发光二极管 - 光电探测器对、200微米熔融石英U形光纤探针和60纳米（20×）AuNP标记物的P-FAB在缓冲液和合成尿液中的检测限分别低至1飞克/毫升和10飞克/毫升。此外，抗结核分枝杆菌LAM IgM结合的传感器探针和储存在4°C的AuNP试剂在长达45天内保持稳定。基于P-FAB的结核分枝杆菌LAM传感器展示了其用于现场结核病诊断的潜力。
