Status : Verified
| Personal Name | Escobar, Anna Mae A. |
|---|---|
| Resource Title | Biocompatible synthesis of gold-core silica shell nanoparticles for metal-enhanced fluorescence (MEF) in biosensing |
| Date Issued | 24 June 2026 |
| Abstract | Near-infrared (NIR) fluorescent materials have attracted considerable interest in bioimaging and biosensing, as physiological components such as water and hemoglobin exhibit weak absorption and low intrinsic autofluorescence in this region. The clinically approved dye indocyanine green (ICG; excitation/emission 789/813 nm) holds valuable potential in photothermal and photoacoustic imaging owing to its high absorption cross-section and environment-responsive optical properties, despite its low quantum yield and short lifetime. To enhance its photostability and control aggregation, ICG has been paired with NIR gold nanostructures. However, most reported ICG–gold assemblies rely on cytotoxic surfactants (e.g., CTAB) and strong reducing agents (e.g., NaBH₄), thereby limiting in vivo applications. Consequently, this study synthesized NIR-resonant gold nanotriangles (AuNTs) via a thiosulfate-mediated, surfactant-free method, stabilized using biocompatible zwitterionic amino acid L-cysteine, and added a silica shell, enabling controlled ICG loading while preventing fluorescence quenching from direct metal contact. The resulting AuNT@SiO₂ nanostructures exhibited plasmon resonance above 800 nm, overlapping with ICG absorption. ICG aggregation, emission, and lifetime were assessed by UV-Vis, steady-state fluorescence, and FLIM, respectively, offering insight into nanostructure–ICG photophysical interaction. Metal-enhanced fluorescence (MEF) of ICG remained limited by the aggregation of the dye in aqueous solution, yielding intensity ratios of only 0.865 on AuNP-Cys@SiO₂ and a negligible value on AuNP-CTAB@SiO₂. In contrast, pairing the fully and partially biocompatible silica-coated AuNPs with the visible-region dye FITC gave maximum enhancement factors of 1.127 ± 0.047 and 1.61 ± 0.16, respectively. These results indicate potential for MEF-based biosensing but warrant further study of ICG immobilization and amino acid–silica growth compatibility. |
| Degree Course | MS in Materials Science and Engineering |
| Language | English |
| Keyword | biocompatible synthesis; indocyanine green; gold nanotriangle; near-infrared; fluorescence intensity; fluorescence lifetime; amino acids; thiosulfate synthesis |
| Material Type | Thesis/Dissertation |
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Category : I - Has patentable or registrable invention of creation.
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