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The SARS-CoV-2 pandemic, an ongoing global health crisis, has revealed the need for new technologies that integrate the sensitivity and specificity of RT-PCR tests with a faster time-to-detection. Here, an emulsion loop-mediated isothermal amplification (eLAMP) platform was developed to allow for the compartmentalization of LAMP reactions, leading to faster changes in emulsion characteristics, and thus lowering time-to-detection. Within these droplets, ongoing LAMP reactions lead to adsorption of amplicons to the water-oil interface, causing a decrease in interfacial tension, resulting in smaller emulsion diameters. Changes in emulsion diameter allow for the monitoring of the reaction by use of angle-dependent light scatter (based off Mie scatter theory). Mie scatter simulations confirmed that light scatter intensity is diameter-dependent and smaller colloids have lower intensity values compared to larger colloids. Via spectrophotometers and fiber optic cables placed at 30° and 60°, light scatter intensity was monitored. Scatter intensities collected at 5 min, 30° could statistically differentiate 10, 10 3 , and 10 5 copies/μL initial concentrations compared to NTC. Similarly, 5 min scatter intensities collected at 60° could statistically differentiate 10 5 copies/μL initial concentrations in comparison to NTC. The use of both angles during the eLAMP assay allows for distinction between high and low initial target concentrations. The efficacy of a smartphone-based platform was also tested and had a similar limit of detection and assay time of less than 10 min. Furthermore, fluorescence-labeled primers were used to validate target nucleic acid amplification. Compared to existing LAMP assays for SARS-CoV-2 detection, these times-to-detections are very rapid., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The design of molecular nanodevices attracted great interest in these years. Herein, a reusable, sensitive and specific aptasensor was constructed based on an extension-contraction movement of DNA interconversion for the application of human thrombin detection. The present biosensor was based on resonance light scattering (RLS) using magnetic nanoparticles (MNPs) as the RLS probe. MNPs coated with streptavidin can combine with biotin labeled thrombin aptamers. The combined nanoparticles composite is monodispersed in aqueous medium. When thrombin was added a sandwich structure can form on the surface of MNPs, which induced MNPs aggregation. RLS signal was therefore enhanced, and there is a linear relationship between RLS increment and thrombin concentration in the range of 60pM-6.0nM with a limit of detection at 3.5pM (3.29S B /m, according to the recent recommendation of IUPAC). The present aptasensor can be repeatedly used for at least 6 cycling times by heat to transfer G-quadruplex conformation to single strand of DNA sequence and release thrombin. MNPs can be captured by applying the external magnetic field. Furthermore, the proposed biosensor was successfully applied to detect thrombin in human plasma., (Copyright © 2017 Elsevier B.V. All rights reserved.)

We described a novel resonance light scattering (RLS) sensor for the specific recognition of trace quantities of Hepatitis A Virus (HAV); the sensor was based on a mussel-inspired hepatitis molecularly imprinted polymer. As a recognition element, polydopamine (PDA)-coated totivirus-imprinted polymer was introduced on the surface of SiO 2 nanoparticles (virus-imprinted SiO 2 @PDA NPs) using an efficient one-step synthesis method. The target virus was selectively captured by the imprinted polymer films, thereby increasing the RLS intensity. A simple fluorescence spectrophotometer was employed to measure the changes in the intensity. The enhanced RLS intensity (∆I RLS ) was proportional to the concentration of HAV in the range of 0.04-6.0nmol∙L -1 , with a low limit of detection of 8.6pmol∙L -1 . The selectivity study confirmed that the resultant HAV-imprinted SiO 2 @PDA NPs possessed high selectivity for HAV. The sensor was successfully applied for the direct detection of additional HAV from a 20,000-fold dilution of human serum. The proposed strategy is simple, eco-friendly, highly selective, and sensitive., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This work describes a sensitive approach utilizing non-cross-linking aggregation of double-stranded DNA modified gold nanoparticles (dsDNA-AuNPs) for the detection of mercury ions (Hg(2+)) by resonance Rayleigh scattering (RRS) method for the first time. The double-stranded DNA contains a mismatched T-T base pair in the chain terminus, resulting in a flexible DNA tail and preventing the AuNPs from aggregation. Thus, a low RRS signal is obtained. However, in the presence of Hg(2+), the non-cross-linking aggregation of dsDNA-AuNPs occurs, due to the Hg(2+)-mediated coordination of T-Hg(2+)-T base pair. The aggregation of nanoparticles generates a high RRS value. Particularly, the solution color and ultraviolet-visible absorption barely changed under the same conditions, while it is capable of detecting by RRS method with a low detection limit (0.4nM), which is 1000-fold lower than that of the colorimetric method. The proposed method was successfully applied to the detection of Hg(2+) in real samples. The sensitive and selective assay might be inspiring for the development of new detectors for other metal ions or biomolecules., (Copyright © 2014 Elsevier B.V. All rights reserved.)