Microfluidic Magnetic Analyte Delivery Technique for Separation, Enrichment, and Fluorescence Detection of Ultratrace Biomarkers

Abstract

A microfluidic magnetic analyte delivery (μMAD) technique was developed to realize sample preparation and ultrasensitive biomarker detection. A simply designed microfluidic device was employed to carry out this technique, including a poly(dimethylsiloxane)-glass hybrid microchip having four straight rectangular channels and a permanent magnet. In the μMAD process, functionalized magnetic beads (MBs) were used to recognize and isolate analytes from a complex sample matrix, deliver analytes into tiny microchannels, and preconcentrate analytes in the magnetic trapping/detection region for in situ fluorescence detection. In the feasibility study and sensitivity optimization, horseradish peroxidase-labeled MBs were used, and critical parameters for the signal amplification performance of μMAD were carefully evaluated. At optimized conditions, a sensitivity improvement of at least 2 orders of magnitude was achieved. As a proof of concept, μMAD was combined with the enzyme-linked immunosorbent assay (ELISA), while carcinoembryonic antigen (CEA), prostate-specific antigen (PSA), and interleukin 6 (IL-6) were selected as model biomarkers. The limits of detection (LODs) of μMAD-ELISA were as low as 0.29 pg/mL for CEA, 0.047 pg/mL for PSA, and 0.021 pg/mL for IL-6, which corresponded to an over 200-fold reduction compared to their commercial ELISA results. Meanwhile, μMAD-ELISA revealed high selectivity and reproducibility. In clinical sample analysis, good accuracy was acquired for human serum analysis relative to commercial ELISA kits, and satisfied recoveries of 85.1−102% with RSDs of 1.7−9.8% for IL-6 and 84.7−113% with RSDs of 3.2−8.3% for interferon-γ were obtained. This ultrasensitive and easy operation technique provides a valuable approach for trace-level biomarker detection for practical applications.

Microfluidic systems for the analysis of blood‐derived molecular biomarkers

“…Commonly, microbeads are used in suspension because their size allows one to mix them appropriately with the assay reagents and then be easily identified with flow cytometry [213,249,252]. When used in microfluidics, beads are typically retained inside the device by either (i) physical barriers patterned within the microfluidic chan-nel [253] and (ii) biorecognition approaches [214,231], or (iii) by external magnetic fields while using paramagnetic beads [215,254,255]. Additionally, nano/microbeads are chemically stable and easy to mass-produce using PMMA, gold, or polystyrene materials.…”

Recent Advances in Digital Biosensing Technology

“…This strategy has also been used to concentrate the antigen in a specific zone for detection. Sensitivity and washing steps can be significantly improved to the pg level by concentrating the beads [ 48 , 49 , 50 ]. The entire movement of the magnetic droplet relies on the mass of the beads, the magnet itself, and the surface properties of the device.…”

Molecularly imprinted monoliths: Recent advances in the selective recognition of biomacromolecules related biomarkers

“…Over the years, tremendous efforts have been invested to develop reliable and cost‐effective strategies for the specific detection of intracellular biomarkers or biomarkers on the pathological cell surface. These methods include HPLC [7], electrophoresis [8], ELISA [9], polymerase chain reaction [10], surface plasmon resonance [11], surface‐enhanced Raman spectroscopy [12], colorimetric assay [13], electrochemical assay [14], and fluorescent detection [15], and so forth. However, biomarkers are often present at low levels in complex biological fluids that contain a high abundance of interfering compounds.…”