Dual-Signal Readout Nanospheres for Rapid Point-of-Care Detection of Ebola Virus Glycoprotein

Rapid detection of highly contagious pathogens is the key to increasing the probability of survival and reducing infection rates. We developed a sensitive and quantitative lateral flow assay for detection of Ebola virus (EBOV) glycoprotein with a novel multifunctional nanosphere (RNs@Au) as a reporter. Each RNs@Au contains hundreds of quantum dots and dozens of Au nanoparticles and can achieve enhanced dual-signal readout (fluorescence signal for quantitative detection and colorimetric signal for visual detection). Antibody (Ab) and streptavidin (SA) were simultaneously modified onto the RNs@Au to label the target and act as signal enhancer. After the target was labeled by the Ab–RNs@Au–SA and captured on the test line, biotin-modified RNs@Au was used to amplify the dual signal by the reaction of SA with biotin. The assay enables naked-eye detection of 2 ng/mL glycoprotein within 20 min, and the quantitative detection limit is 0.18 ng/mL. Additionally, the assay has been successfully tested in field work for detecting EBOV in spiked urine, plasma, and tap water samples and is thus a promising candidate for early diagnosis of suspect infections in EBOV-stricken areas

Ultrasensitive Ebola Virus Detection Based on Electroluminescent Nanospheres and Immunomagnetic Separation

The 2014–16 Ebola virus (EBOV) outbreak in West Africa has attracted widespread concern. Rapid and sensitive detection methods are urgently needed for diagnosis and treatment of the disease. Here, we propose a novel method for EBOV detection based on efficient amplification of electroluminescent nanospheres (ENs) coupled with immunomagnetic separation. Uniform ENs are made by embedding abundant amounts of CdSe/ZnS quantum dots (QDs) into copolymer nanospheres through simple ultrasound. Compared to QDs, ENs can enhance electroluminescence (ECL) signals by approximately 85-fold, achieving a signal-to-background ratio high enough for EBOV detection. The introduction of magnetic nanobeads (MBs) can selectively separate targets from complex samples, simplifying the operation process and saving time. The presence of MBs can amplify ECL by approximately 3-fold, improving detection sensitivity. By integration of ENs with MBs, a sensitive electroluminescence biosensor is established for EBOV detection. The linear range is 0.02–30 ng/mL with a detection limit of 5.2 pg/mL. This method provides consistent reproducibility, specificity, and anti-interference ability and is highly promising in clinical diagnosis applications

Cellular-Beacon-Mediated Counting for the Ultrasensitive Detection of Ebola Virus on an Integrated Micromagnetic Platform

Ebola virus (EBOV) disease is a complex zoonosis that is highly virulent in humans and has caused many deaths. Highly sensitive detection of EBOV is of great importance for early-stage diagnosis for increasing the probability of survival. Herein, we established a cellular-beacon-mediated counting strategy for an ultrasensitive EBOV assay on a micromagnetic platform. The detection platform, which was assisted by on-demand magnetic-field manipulation, showed high integration and enhanced complex-sample pretreatment by magnetophoretic separation and continuous-flow washing. Cellular beacons (i.e., fluorescent cells) with superior optical properties were used as reporters, and each cellular beacon was used as a fluorescent tracking unit to quantify EBOV by counting the numbers of individual fluorescent signals on the micromagnetic platform. This method achieves high sensitivity with a detection limit as low as 2.6 pg/mL, and the detection limit shows little difference in a complex matrix. In addition, it has excellent specificity and good reproducibility. These results indicate that this method proposes an ultrasensitive detection strategy for early diagnosis of the disease