Publicação
Optical fibre LSPR immunosensing: from gold nanoparticles production to biosensor characterisation
| Resumo: | The Localised Surface Plasmon Resonance (LSPR)-based sensors have become a leading label-free biosensing technology. Despite their prominence, these sensors still require refinement in key areas, including sensitivity, specificity, repeatability, reproducibility and configuration adaptable for point-of-care biosensing. In this dissertation, work was undertaken to improve these parameters by developing LSPR sensors in Optical Fibre (OF) in a reflection configuration. In order to achieve this objective, the following tasks were contemplated: synthesis of Gold Nanoparticles (AuNPs) of 3 different sizes (20, 40, and 80 nm); morphological and stability analysis of the NPs; production of OF probes with a 600 μm diameter; comparison of two silanes for binding AuNPs to OF (APTES vs MPTMS). Additionally, tests were conducted on the repeatability, reproducibility, and characterisation of the probes, assessing their absorbance spectrum as a function of the of surrounding environment’s Refractive Index (RI). Finally, the OF-LSPR approach with the best sensitivity and reproducibility was biofunctionalised with antibodies to test the performance of these probes as biosensors. Overall, the results showed that the probes functionalized with smaller AuNPs exhibited the best performance, achieving an average sensitivity of 3.96±0.32 Arb.u./R.I.u. over the widest consistent response range 1.3342-1.3356 R.I.u.. Repeatability and reproducibility were statistically evaluated using the Intraclass Correlation Coefficient 3 (ICC3), resulting in values of ICC3 ≥ 0.98 for both figures of merit. These results supported the viability of this approach, which combines the advantages of LSPR phenomena with the versatility of the OF reflection configuration. Subsequently, a pilot immunoassay test for Human Serum Albumin (HSA) demonstrated that the developed biosensor identifies analyte concentrations in an operating range of 0.001-10 ng/mL, with an average sensitivity of (10.5±1.9)× 10⁻⁴ Arb.u./log(ng/mL). This research corroborates and expands the existing literature, laying the foundations for methodological advances in LSPR biodetection. The inherent versatility and affordable cost of the developed immunosensor, combined with its suitability for direct, real-time monitoring of molecular interactions in low-volume samples, positions it for future integration into point-of-interest biodetection applications. |
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| Autores principais: | Tavares, Gil Coelho |
| Assunto: | Biosensing Gold nanoparticles Localised surface plasmon resonance Optical fibre Refractive index |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Universidade de Aveiro |
| Idioma: | inglês |
| Origem: | RIA - Repositório Institucional da Universidade de Aveiro |
| Resumo: | The Localised Surface Plasmon Resonance (LSPR)-based sensors have become a leading label-free biosensing technology. Despite their prominence, these sensors still require refinement in key areas, including sensitivity, specificity, repeatability, reproducibility and configuration adaptable for point-of-care biosensing. In this dissertation, work was undertaken to improve these parameters by developing LSPR sensors in Optical Fibre (OF) in a reflection configuration. In order to achieve this objective, the following tasks were contemplated: synthesis of Gold Nanoparticles (AuNPs) of 3 different sizes (20, 40, and 80 nm); morphological and stability analysis of the NPs; production of OF probes with a 600 μm diameter; comparison of two silanes for binding AuNPs to OF (APTES vs MPTMS). Additionally, tests were conducted on the repeatability, reproducibility, and characterisation of the probes, assessing their absorbance spectrum as a function of the of surrounding environment’s Refractive Index (RI). Finally, the OF-LSPR approach with the best sensitivity and reproducibility was biofunctionalised with antibodies to test the performance of these probes as biosensors. Overall, the results showed that the probes functionalized with smaller AuNPs exhibited the best performance, achieving an average sensitivity of 3.96±0.32 Arb.u./R.I.u. over the widest consistent response range 1.3342-1.3356 R.I.u.. Repeatability and reproducibility were statistically evaluated using the Intraclass Correlation Coefficient 3 (ICC3), resulting in values of ICC3 ≥ 0.98 for both figures of merit. These results supported the viability of this approach, which combines the advantages of LSPR phenomena with the versatility of the OF reflection configuration. Subsequently, a pilot immunoassay test for Human Serum Albumin (HSA) demonstrated that the developed biosensor identifies analyte concentrations in an operating range of 0.001-10 ng/mL, with an average sensitivity of (10.5±1.9)× 10⁻⁴ Arb.u./log(ng/mL). This research corroborates and expands the existing literature, laying the foundations for methodological advances in LSPR biodetection. The inherent versatility and affordable cost of the developed immunosensor, combined with its suitability for direct, real-time monitoring of molecular interactions in low-volume samples, positions it for future integration into point-of-interest biodetection applications. |
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