Upconverting nanoparticles in sensing technologies: from design and synthesis to multifunctional nanoplatforms and portable devices

• Ano de defesa: 2024
• Autor(a) principal: Arai, Marylyn Setsuko
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: biosensors; biossensores; conversão ascendente; luminescent sensors; multifuncionalidade; multifunctionality; nanomateriais; nanomaterials; sensores luminescentes; upconversion
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/18/18158/tde-06012025-155057/

Upconverting nanoparticles (UCNPs) have emerged as powerful tools in the field of sensing, offering unique advantages due to their ability to convert low-energy infrared light into higher-energy visible or ultraviolet light. This property makes UCNPs highly desirable for developing advanced sensors across physical, chemical, and biological domains. The use of UCNPs in sensors allows for non-invasive, highly sensitive, and selective detection methods, which are particularly beneficial in environments requiring minimal interference and high precision. This thesis presents the development and application of UCNP-based sensors for various key areas: portable biomarker detection, design of multifunctional nanomaterial platforms, and bacterial differentiation. First, we introduce the Enhanced Luminescence Lateral-Flow Assay (ELLA) to rapidly detect acute kidney injury biomarkers in urine samples. Utilizing Er+3- and Tm+3-doped UCNPs, which are enhanced with a gold-coated mesoporous silica shell, this sensor demonstrates a remarkable 40-fold increase in emission intensity, facilitating the accurate detection of KIM-1 and NGAL biomarkers with limits of detection as low as 0.28 ng/mL and 0.23 ng/mL, respectively. The developed portable sensor delivers results within 15 minutes, showcasing its potential for early disease diagnosis. Next, we describe a multifunctional nanoplatform that combines Tm+3-doped UCNPs with a Cu(I) complex for applications in oxygen sensing, optical thermometry, and emission color tuning. The platform utilizes Luminescent Resonance Energy Transfer (LRET) to achieve efficient energy transfer, enabling red emission from the Cu(I) complex while retaining the UCNP\'s original emissions for thermometry. This dual-functionality allows for sensitive oxygen detection, with a Stern-Volmer constant of 1.64, and precise temperature measurements, with relative sensitivities of up to 1% K-1. The ability to modulate emission colors adds a customizable aspect to this nanoplatform, making it a versatile tool. Finally, we address the critical challenge of rapid bacterial detection and differentiation through a novel UCNP-based luminescent sensor. By functionalizing UCNPs with antibiotics - vancomycin for Gram-positive and polymyxin-B for Gram-negative bacteria - and using gold nanoparticles as quenchers, this sensor leverages a ratiometric \"turn-on\" mechanism for detection. The sensor effectively distinguishes between Gram-positive and Gram-negative bacteria, demonstrating excellent correlation with actual bacterial concentrations across a broad range, making it a promising candidate for environmental and clinical diagnostics. Together, these studies highlight the versatility and potential of UCNPs in developing novel sensors for a variety of applications, offering significant advancements in the fields of diagnostics, environmental monitoring, and beyond.