Optical modulation biosensing system for rapid detection of biological targets at low concentrations

Abstract

In many sensitive assays, target molecules are tagged using fluorescently labeled probes and captured using magnetic beads. Here, we introduce an optical modulation biosensing (OMB) system, which aggregates the beads into a small detection area and separates the signal from the background noise by manipulating the laser beam in and out of the cluster of beads. Using the OMB system to detect human interleukin-8, we demonstrated a limit of detection of 0.02 ng/L and a 4-log dynamic range. Using Zika-positive and healthy individuals’ serum samples, we show that the OMB-based Zika IgG serological assay has 96% sensitivity and 100% specificity.

Recent Advances in Rapid and Highly Sensitive Detection of Proteins and Specific DNA Sequences Using a Magnetic Modulation Biosensing System

“…To further evaluate the OMB system's performance in a simulated clinical immunoassay (Figure 16b), recombinant human IL-8 was used with a commercially available IL-8 assay kit. The calculated LoD of the OMBbased human IL-8 assay in buffer was 0.02 ng/L [61]. This LoD is comparable with the LoD (0.04 ng/L) achieved by the MMB system for the same assay [11].…”

“…The recently introduced optical modulation system (OMB) integrates the operating principles of the MMB (i.e., measuring the signal from both the beads and the background) and the MAB systems (i.e., fixing the cluster of beads in a single spot) [61]. In OMB, the beads are immobilized to one side of the sample holder and the relative movement between the beads and the laser beam is achieved by manipulating the laser beam from side to side.…”

“…Similar to the MMB system, the OMB system (Figure 14b) uses a 532 nm laser diode, working at 0.25 mW. The laser beam is moved laterally back and forth by a scanning galvo mirror and deflected by a dichroic mirror into a microscope objective lens [61]. The objective lens focuses the beam to a 150 µm diameter spot on a sample cell containing the magnetic beads.…”