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Optimizing Plasmonic Gold Nanorod Deposition on Glass Surfaces for High-Sensitivity Refractometric Biosensing
Youngkyu Hwang1, Dong Jun Koo1, Abdul Rahim Ferhan2
1School of Chemical Engineering and Translational Nanobioscience Research Center, Sungkyunkwan University, Suwon 16419, Korea.
Nanomaterials (Basel, Switzerland)
|October 14, 2022
Summary
Optimizing (3-aminopropyl)triethoxysilane (APTES) concentration for gold nanorod (AuNR) surface functionalization enhances nanoplasmonic biosensor performance. This study reveals an intermediate APTES range yielding high AuNR density and superior label-free molecular diagnostics.
Area of Science:
- Nanotechnology
- Surface Chemistry
- Biosensing
Background:
- Gold nanorods (AuNRs) are crucial for label-free nanoplasmonic biosensing due to their surface sensitivity.
- Effective AuNR deposition requires maximizing surface density and minimizing aggregation, often via self-assembled monolayers (SAMs).
- Previous studies used fixed SAM concentrations, limiting understanding of density-dependent effects on AuNR deposition and sensing.
Purpose of the Study:
- To systematically investigate the impact of (3-aminopropyl)triethoxysilane (APTES) concentration on AuNR deposition and nanoplasmonic biosensing performance.
- To identify an optimal APTES concentration range for fabricating high-performance AuNR-coated surfaces.
- To evaluate the resulting biosensor's sensitivity for molecular diagnostics.
Main Methods:
- Systematic variation of APTES concentration (1-30% v/v) for SAM preparation on glass surfaces.
- Characterization of AuNR deposition using scanning electron microscopy (SEM) and UV-visible spectroscopy.
- Assessment of bulk refractive index sensitivity and performance in protein and antigen-antibody detection assays.
Main Results:
- An intermediate APTES concentration range was identified, maximizing individual AuNR density with minimal aggregation.
- This optimal range also resulted in the highest peak wavelength in aqueous solution.
- Bulk refractive index sensitivity varied from 125 to 290 nm/RIU, with optimized platforms showing ~8-fold higher sensitivity in low protein detection compared to previous methods.
Conclusions:
- Controlling APTES concentration during SAM formation is critical for optimizing AuNR deposition and nanoplasmonic biosensor fabrication.
- The identified intermediate APTES concentration range significantly enhances AuNR surface density, reduces aggregation, and improves sensing performance.
- The optimized AuNR-based platform demonstrates high surface sensitivity, enabling sensitive label-free molecular diagnostics, particularly for low analyte concentrations.
