Abstract
We report a biosensing method based on magnetic particles where coated magnetic particles are used for immunomagnetic separation, and uncoated magnetic particles are used for signal enhancement. To quantify the signal amplification, optical micrographs are analyzed to measure changes in pixel area and pixel intensity. Microcontact-printed surface receptors are arranged in alternating lines on gold chips, enabling differential calculations. In a model experiment, target molecules-streptavidin-are first captured and separated by biotin-coated magnetic particles, and then exposed to a gold surface functionalized with biotin-coupled bovine serum albumin, forming a sandwich assay. Applying a magnetic field and introducing uncoated magnetic particles resulted in accumulation around magnetic particles in the sandwich assay and enhancement of the contrast to noise ratio at least by eight-fold in a range of 0.1–100 μM.
Highlights
The advances in micro/nano fabrication methods have led to the development of various biosensing platforms using magnetic particles
For the second set of experiments, the biotin-coated magnetic beads simultaneously served two main purposes: (1) as immunomagnetic capture agents to capture and separate the target; (2) as base beads immobilized on the surface to attract iron nano particles under an applied magnetic field for signal amplification
Schematic of the complete biosensing experiments: streptavidin streptavidin was was used used as the target biotin‐coated beads captured and separated the target, signal amplification occurred in the molecule, biotin-coated microfluidic chamber using using iron iron nano nano particles
Summary
The advances in micro/nano fabrication methods have led to the development of various biosensing platforms using magnetic particles. In a companion paper [21] we introduced an alternative signal amplification method based on magnetic bead accumulation In this method, immunomagnetic beads are first used to capture and separate the target molecules; under an external magnetic field, added uncoated magnetic particles form flocs around the immunomagnetic beads due to magnetic dipole–dipole interactions. The first set of experiments was performed to the in accumulation of iron nano and around the magnetic particles already immobilized on investigate the gold chip a microfluidic chamber, particles around the magnetic particles already immobilized on the gold chip in a microfluidic to investigate the different quantification methods using the recorded images. (1) as immunomagnetic capture agents to capture and separate the target (streptavidin); (2) as base beads immobilized on the surface to attract iron nano particles under an applied magnetic field for signal amplification. 3 ofthe surface to attract iron nano particles under an applied magnetic field for signal amplification
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