Abstracts
Luminescent materials for imaging, sensors and theranostics
Spectroscopic studies of NaYF4, YVO4,and AuNRs/NPs for multifunctional superparticlesTamires M. Oliveira1, Paulo C. de S. Filho1
1University of Campinas, Chemistry Institute, Brazil
E-mail: t212524@dac.unicamp.br
The quest for materials exhibiting orthogonal properties, termed multimodal/multifunctional systems, is driving the development of novel synthesis methodologies aimed at achieving precise morphological and structural control. An appealing alternative to complex core@shell systems is the controlled aggregation of diverse nanoparticles into submicrometric structures called superparticles. Given the increasing demand in nanomedicine for materials capable of locally monitoring temperature (luminescent nanothermometry) and inducing controlled localized heating under light (phototherapy), the combination of luminescent and plasmonic particles is attractive for theranostic applications. Prior to controlled aggregation steps, precise tuning of surface and spectroscopic characteristics of individual luminescent and plasmonic particles is mandatory. In this context, we have prepared several rare-earth-based nanoparticles (RE NP) with different excitation wavelengths (λexc), and AuNRs/AuNPs. NaYF4:Yb, Er and NaYF4:Nd, Yb, Er exhibited Er3+ emission in the green (2H11/2 → 4I and 4S3/2 → 4I15/2) and red (4I13/2 → 4I15/2) regions with λexc of 980 and 808 nm, respectively, and both exhibited β-NaYF4 crystal structures. Tetragonal YVO4:Eu3+ particles displayed high-intensity Eu3+ emissions (5D0 → 7Fn, n= 1, 2, 3 and 4) under λexc = 270 nm. Additionally, AuNRs were synthesized using the seed-mediated growth method, and AuNPs were prepared using the classic Turkevich method. The upconversion emission of NaYF4 resulted in thermal sensitivities (SR) ranging between 0.2 and 1.8% K-1 for both samples. The individual NPs showed promising properties for further combination into superparticles for thermometry and thermal therapy. Additional studies will further comprise the control of the aggregation processes using light to initiate crosslinking between the capping agents on the particle surfaces.
Keywords: Spectroscopy, Rare Earth, Nanothermometry, Theranostic, Superparticles.
Acknowledgments: FAPESP (process: 2022/05118-9), CAPES, CNPq, Santander, FAEPEX.