Optimizing and Quantifying Gold Nanospheres Based on LSPR Label-Free Biosensor for Dengue Diagnosis

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Optical Sensing

Background:

• Localized surface plasmon resonance (LSPR) is crucial for sensing, with efficiency depending on refractive index sensitivity (ηRIS) and spectral width (FWHM).
• Complex nanostructures offer good ηRIS but often have wide LSPR spectra, limiting detection sensitivity.
• Developing precise, label-free biosensors requires optimizing LSPR features for high sensitivity and narrow spectral peaks.

Purpose of the Study:

• To develop a facile, label-free, solution-based LSPR immunosensor.
• To optimize gold nanoparticle (Au NP) size for enhanced sensing performance.
• To evaluate the sensor's capability for detecting dengue NS1 antigens.

Main Methods:

• Utilized 3D full-wave field analysis to evaluate optical properties and optimize Au NP size.
• Investigated the effect of Au NP radius (5-50 nm) on spectral resonance and LSPR parameters.
• Employed Campbell's model for evaluating molecular sensing performance and applied the platform for dengue NS1 antigen detection.

Main Results:

• Optimized Au NP radius (30 nm) yielded a high figure of merit (FoM) of 2.3 and a sharp FWHM of 44 nm.
• Demonstrated a red-shift in spectral resonance from 520 nm to 552 nm with increasing Au NP size.
• Achieved a limit of quantification of 0.07 μg/mL (1.50 nM) for dengue NS1 antigens.

Conclusions:

• The optimized Au NP-based LSPR immunosensor offers high precision and sensitivity for molecular detection.
• This approach provides a new paradigm for engineering efficient and label-free immunosensor platforms.
• The developed sensor demonstrates significant potential for clinical diagnostics, particularly for infectious diseases like dengue.