Two-Color Lateral Flow Assay for Multiplex Detection of Causative Agents Behind Acute Febrile Illnesses

Acute undifferentiated febrile illnesses (AFIs) represent a significant health burden worldwide. AFIs can be caused by infection with a number of different pathogens including dengue (DENV) and Chikungunya viruses (CHIKV), and their differential diagnosis is critical to the proper patient management. While rapid diagnostic tests (RDTs) for the detection of IgG/IgM against a single pathogen have played a significant role in enabling the rapid diagnosis in the point-of-care settings, the state-of-the-art assay scheme is incompatible with the multiplex detection of IgG/IgM to more than one pathogen. In this paper, we present a novel assay scheme that uses two-color latex labels for rapid multiplex detection of IgG/IgM. Adapting this assay scheme, we show that 4-plex detection of the IgG/IgM antibodies to DENV and CHIKV is possible in 10 min by using it to correctly identify 12 different diagnostic scenarios. We also show that blue, mixed, and red colorimetric signals corresponding to IgG, IgG/IgM, and IgM positive cases, respectively, can be associated with distinct ranges of hue intensities, which could be exploited by analyzer systems in the future for making accurate, automated diagnosis. This represents the first steps toward the development of a single RDT-based system for the differential diagnosis of numerous AFIs of interest

Orthogonal Nanoparticle Size, Polydispersity, and Stability Characterization with Near-Field Optical Trapping and Light Scattering

Here we present and demonstrate a new technique for simultaneously characterizing the size, polydispersity, and colloidal stability of nanoparticle suspensions. This method relies on tracking each nanoparticle’s motion in three spatial dimensions as it interacts with the evanescent field of an optical waveguide. The motion along the optical propagation axis of the waveguide provides insight into the polydispersity of a nanoparticle suspension. Horizontal motion perpendicular to the propagation axis gives the diffusion coefficient and particle size. In the direction normal to the surface, statistical analysis of the scattered light intensity distribution gives a map of the interaction energy landscape and insight into the suspension stability. These three orthogonal measurements are made simultaneously on each particle, building up population level insights from a single-particle rather than ensemble-averaged basis. We experimentally demonstrate the technique using polystyrene spheres obtaining results consistent with the manufacturer’s specifications for these suspensions. For NIST-traceable polystyrene size standard spheres, we measure a variability in the hydrodynamic radius of ±5 nm, compared with the manufacturer’s certified measurement of ±9 nm in the geometric diameter made using transmission electron microscopy

Media 1: Gel-based optical waveguides with live cell encapsulation and integrated microfluidics

Originally published in Optics Letters on 01 May 2012 (ol-37-9-1472

Angular Orientation of Nanorods Using Nanophotonic Tweezers

Near-field optical techniques have enabled the trapping, transport, and handling of nanoscopic materials much smaller than what can be manipulated with traditional optical tweezers. Here we extend the scope of what is possible by demonstrating angular orientation and rotational control of both biological and nonbiological nanoscale rods using photonic crystal nanotweezers. In our experiments, single microtubules (diameter 25 nm, length 8 μm) and multiwalled carbon nanotubes (outer diameter 110–170 nm, length 5 μm) are rotated by the optical torque resulting from their interaction with the evanescent field emanating from these devices. An angular trap stiffness of κ = 92.8 pN·nm/rad²·mW is demonstrated for the microtubules, and a torsional spring constant of 22.8 pN·nm/rad²·mW is measured for the nanotubes. We expect that this new capability will facilitate the development of high precision nanoassembly schemes and biophysical studies of bending strains of biomolecules

Angular Orientation of Nanorods Using Nanophotonic Tweezers

Near-field optical techniques have enabled the trapping, transport, and handling of nanoscopic materials much smaller than what can be manipulated with traditional optical tweezers. Here we extend the scope of what is possible by demonstrating angular orientation and rotational control of both biological and nonbiological nanoscale rods using photonic crystal nanotweezers. In our experiments, single microtubules (diameter 25 nm, length 8 μm) and multiwalled carbon nanotubes (outer diameter 110–170 nm, length 5 μm) are rotated by the optical torque resulting from their interaction with the evanescent field emanating from these devices. An angular trap stiffness of κ = 92.8 pN·nm/rad²·mW is demonstrated for the microtubules, and a torsional spring constant of 22.8 pN·nm/rad²·mW is measured for the nanotubes. We expect that this new capability will facilitate the development of high precision nanoassembly schemes and biophysical studies of bending strains of biomolecules

Angular Orientation of Nanorods Using Nanophotonic Tweezers

Near-field optical techniques have enabled the trapping, transport, and handling of nanoscopic materials much smaller than what can be manipulated with traditional optical tweezers. Here we extend the scope of what is possible by demonstrating angular orientation and rotational control of both biological and nonbiological nanoscale rods using photonic crystal nanotweezers. In our experiments, single microtubules (diameter 25 nm, length 8 μm) and multiwalled carbon nanotubes (outer diameter 110–170 nm, length 5 μm) are rotated by the optical torque resulting from their interaction with the evanescent field emanating from these devices. An angular trap stiffness of κ = 92.8 pN·nm/rad²·mW is demonstrated for the microtubules, and a torsional spring constant of 22.8 pN·nm/rad²·mW is measured for the nanotubes. We expect that this new capability will facilitate the development of high precision nanoassembly schemes and biophysical studies of bending strains of biomolecules

Anemone pulsatilla

Near-field optical techniques have enabled the trapping, transport, and handling of nanoscopic materials much smaller than what can be manipulated with traditional optical tweezers. Here we extend the scope of what is possible by demonstrating angular orientation and rotational control of both biological and nonbiological nanoscale rods using photonic crystal nanotweezers. In our experiments, single microtubules (diameter 25 nm, length 8 μm) and multiwalled carbon nanotubes (outer diameter 110–170 nm, length 5 μm) are rotated by the optical torque resulting from their interaction with the evanescent field emanating from these devices. An angular trap stiffness of κ = 92.8 pN·nm/rad²·mW is demonstrated for the microtubules, and a torsional spring constant of 22.8 pN·nm/rad²·mW is measured for the nanotubes. We expect that this new capability will facilitate the development of high precision nanoassembly schemes and biophysical studies of bending strains of biomolecules

Setup and experiment demonstrating application of hemoAID to late-phase HS prevention.

<p>A) Setup for integrated device testing simulating late-phase HS B) resistance change, and associated vasopressin concentration change, detected by the biosensor during integrated experiment simulating late phase HS changes in vasopressin concentration. For the first 720 s the vasopressin concentration is gradually lowered until the drug delivery is autonomously activated to counteract the drop in vasopressin (at 15% drop). The line at 720 s shows the point at which drug delivery is activated. The inset shows the vasopressin drop before the drug delivery is activated (simulating the onset of late-phase HS).</p

Drug delivery device activation.

<p>A) Assembly of the drug delivery unit B) vasopressin ejection over 25 s of applied voltage C) increase in biosensor voltage due to drug delivery. The vertical dotted line indicates when the potential was applied (at t = 0 s) and the a sustained spike in voltage occurs after 25 s.</p