Versatile immunosensor using a quantum dot coated silica nanosphere as a label for signal amplification

Area of Science:

• Nanotechnology
• Biosensing
• Electrochemistry

Background:

• Development of sensitive and specific detection methods is crucial for early disease diagnosis.
• Quantum dots (QDs) offer unique optical and electronic properties for biosensing applications.
• Silica nanospheres provide a stable and versatile platform for biomolecule immobilization.

Purpose of the Study:

• To develop a versatile immunosensor for ultrasensitive biomarker detection.
• To utilize cadmium telluride (CdTe) quantum dots (QDs) coated silica nanospheres (Si/QD) as a label for signal amplification.
• To demonstrate the immunosensor's performance using Rabbit IgG as a model protein.

Main Methods:

• Immobilization of QDs and antibodies onto monodisperse silica nanospheres.
• Covalent binding of goat antirabbit IgG antibody to CdTe QDs on silica nanospheres.
• Formation of a "sandwich" immunoreaction on a gold electrode surface.
• Characterization using scanning electron microscopy (SEM) and fluorescence microscopy.
• Detection using electrochemiluminescence (ECL) and square-wave voltammetry (SWV).

Main Results:

• Successful confirmation of the "sandwich" immunoreaction via SEM and fluorescence microscopy.
• Achieved 6.6-fold and 5.9-fold signal enhancements in ECL and SWV for IgG detection, respectively.
• Ultrasensitive detection limits for IgG: 1.3 pg mL⁻¹ (ECL) and 0.6 pg mL⁻¹ (SWV).
• Demonstrated high sensitivity, reproducibility, regeneration, and precision.

Conclusions:

• The developed Si/QD/Ab2 immunosensor offers a versatile and highly sensitive platform for biomarker detection.
• The strategy provides significant signal amplification, enabling ultrasensitive measurements.
• This approach holds vast potential for various biological assays and diagnostics.