Magnetically aggregated biosensors for sensitive detection of biomarkers at low concentrations

Abstract

Detection of biomarkers at low concentrations is essential for early diagnosis of numerous diseases. In many sensitive assays, the target molecules are tagged using fluorescently labeled probes and captured using magnetic beads. Magnetic beads facilitate washing and separation steps, are well suited for automation, and improve the assay sensitivity. Current devices rely on quantifying the target molecules by detecting the fluorescence signal from individual beads. Thus, to detect low concentrations of target molecules, these devices require sophisticated optical detectors, making them bulky and expensive. Here, we propose a compact fluorescence-based system that simply uses a small permanent magnet with a conic tip to aggregate the magnetic beads, forming a cluster of fluorescently labeled probes whose fluorescence signal is much greater than that of a single bead. Using the magnetically aggregated biosensors to detect human Interleukin-8, we demonstrated a limit of detection of 0.1 ng/l and a 4-log dynamic range performance, which is on par with the most sensitive devices but is achieved without their bulk and cost.

A Self-Reference Interference Sensor Based on Coherence Multiplexing

“…The molecular detection and identification methods can be roughly categorized into labeled methods and label-free methods. Due to high sensitivity, labeled methods, e.g., fluorescence ( Sun et al, 2018 ; Burg et al, 2019 ), chemiluminescence ( Jin et al, 2017 ; Li et al, 2017 ), enzyme-linked immunosorbent assay (ELISA) ( Engvall and Perlmann, 1971 ), have been used in many sensing measurements. However, due to the complex structure and reactivity of proteins, an approach of adding additional reagents to improve the accessibility of observation could cause changes in the properties of a target molecule ( MacBeath, 2002 ).…”

Magnetic Particles: Their Applications from Sample Preparations to Biosensing Platforms

“…Human interleukin-8 was detected by fluorescent devices with a CMOS camera. The detection limit was 0.1 ng L −1 [69].…”

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

“…To detect the concentration of the target analyte, an external alternating magnetic field aggregates the beads with the attached target molecules from the entire sample volume into the detection area, where they are moved in and out of an orthogonal laser beam [11]. Reprinted from [15], with the permission of AIP Publishing 2019. Reprinted from [15], with the permission of AIP Publishing 2019.…”