Ultrasensitive Molecular Detection at Subpicomolar Concentrations by the Diffraction Pattern Imaging with Plasmonic...

Area of Science:

• Nanophotonics and Plasmonics
• Optical Sensing Technologies
• Biomolecular Interaction Analysis

Background:

• Highly sensitive detection of trace molecules is crucial for healthcare, environmental monitoring, and security.
• Conventional spectroscopic methods for molecular detection often rely on expensive and bulky equipment.
• Nanophotonic metasurfaces offer promising platforms for advanced molecular sensing applications.

Purpose of the Study:

• To develop a compact, cost-effective, and ultrasensitive sensor for label-free, spectrometer-free detection of trace molecules.
• To demonstrate the sensor's capability for quantitative analysis of biomolecular interactions.
• To enable on-site molecular detection using a simplified imaging-based system.

Main Methods:

• Design and fabrication of a plasmonic metasurface sensor featuring a convex holographic grating.
• Utilizing a monochrome camera to record the first-order diffraction pattern of the metasurface.
• Analyzing changes in the diffraction pattern upon molecule attachment for detection.
• Integration with a microfluidic setup for quantitative biomolecular interaction studies.
• Employing vacuum-free, solution-processed fabrication techniques for cost reduction.

Main Results:

• Demonstrated spectrometer-free and label-free molecular detection by analyzing diffraction patterns.
• Achieved an excellent limit of detection (LOD) of 0.6 picomolar (pM) for human Immunoglobulin G (IgG) interactions.
• Successfully characterized quantitative biomolecular interactions using a microfluidic setup.
• Developed a prototype sensor using cost-effective components like an LED and a consumer-level imaging sensor.

Conclusions:

• The developed plasmonic metasurface sensor provides a novel, ultrasensitive, and cost-effective approach for trace molecule detection.
• The imaging-based detection method eliminates the need for complex spectroscopic equipment, paving the way for portable devices.
• The vacuum-free, solution-processed fabrication significantly reduces manufacturing costs, enhancing commercial viability.
• The sensor shows great potential for on-site applications in diverse fields, including diagnostics and environmental monitoring.