Magnetic Modulation Biosensing for rapid and highly sensitive detection of biomarkers

Sensitive and rapid detection of fluorescent dyes at low concentrations is a well-known challenge in many biological applications. Fluorescently labeled biosensors are widely used in specific DNA sequences detection and protein-protein interactions. Conventional genomic DNA (or RNA) detection methods predominantly rely on polymerase chain reaction (PCR) to achieve high sensitivity. However, PCR is costly, time consuming, and requires expertise in molecular biology. Hence, it is difficult for use in real time measurements. An early diagnosis lab tool should be compact, easy to operate, sensitive, and provide high throughput.

Here I present a novel technology termed Magnetic Modulation Biosensing (MMB) for rapid and highly sensitive detection of biomarkers. MMB relies on coupling magnetic beads to fluorescent labeled probes. Using two external magnetic poles, which are positioned on opposite sides of a small glass cell, the magnetic beads are aggregated into the detection area and set in a 1-D periodic motion, in and out of an orthogonal laser beam. The resulting periodic fluorescent light is collected by a photomultiplier and demodulated using a lock-in amplifier. The method offers high sensitivity since the magnetic field attracts the fluorescently labeled probes from the entire solution volume into a small detection area. The modulation and the narrow detection bandwidth separate the signal from the background noise of the non-magnetized solution. Moreover, the aggregation and modulation of the magnetic beads eliminate the need for separation and washing steps usually incorporated in heterogeneous assays, thereby shortening and facilitating the detection assay.

The MMB system is a generic device that has many applications. In general, any approach that produces fluorescent light as a result of the biorecognition event can utilize the MMB system to detect low concentrations of labeled probes. The ability to detect, for example, specific DNA sequences, rapidly, simply, and at low concentrations, is important for the development of a portable, high-throughput tool that enables early detection of pathogens and biomarkers.