resumo
Luminescent nanoparticles have shown great potential for thermal sensing in bio-applications. Nonetheless, these materials lack water dispersibility that can be overcome by modifying their surface properties with water dispersible molecules such as cysteine. Herein, we employ LiYF4:Er3+/Yb3+ upconverting nanoparticles (UCNPs) capped with oleate or modified with cysteine dispersed in cyclohexane or in water, respectively, as thermal probes. Upconversion emission was used to sense temperature with a relative thermal sensitivity of similar to 1.24% K-1 (at 300 K) and a temperature uncertainty of 0.8 K for the oleate capped and of 0.5 K for cysteine modified NPs. To study the effect of the cysteine modification in the heat transfer processes, the thermal conductivity of the nanofluids was determined, yielding 0.123(6) W m(-1) K-1 for the oleate capped UCNPs dispersed in cyclohexane and 0.50(7) W m(-1) K-1 for the cysteine modified UCNPs dispersed in water. Moreover, through the heating curves, the nanofluids' thermal resistances were estimated, showing that the cysteine modification partially prevents heat transfer.
palavras-chave
UP-CONVERSION NANOPARTICLES; NAYF4 NANOCRYSTALS; YB3+; CONDUCTIVITY; THERMOMETERS; RESISTANCE
categoria
Chemistry; Science & Technology - Other Topics; Materials Science
autores
Gonçalves, JM; Bastos, ARN; Ribeiro, SJL; Carlos, LD; Longo, RL; Caiut, JMA; Ferreira, RAS
nossos autores
Ana Rita da Naia Bastos
Investigador
João Marcos Gonçalves
Estudante de doutoramento
Luís Carlos
Professor Catedrático
Maria Rute de Amorim e Sá Ferreira André
Professor CatedráticoProjectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
Sondas neuronais fotónicas integradas para computação neuromórfica (PHEASANT)
Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)
agradecimentos
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020), financed by national funds through the FCT/MCTES (PIDDAC) and the project PHEASANT (2022.15735.CMU) under the Carnegie Mellon Portugal Program. Also, this study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Brasil (CAPES) - Finance Code 001 and Capes PrInt program. The authors acknowledge the Brazilian funding agency FAPESP (Proc. 2016/11670-5, Proc. 2019/18828-1), as well as the University of Sao Paulo.