Tuning the Photothermal Effect of Carboxylated-Coated Silver Nanoparticles through pH-Induced Reversible Aggregation.

Autor:	Cativa NM; Nanostructured Polymer Division, INTEMA, UNMDP-CONICET, Avenida Juan B. Justo 4302, B7608FDQ Mar del Plata, Argentina., dell'Erba IE; Nanostructured Polymer Division, INTEMA, UNMDP-CONICET, Avenida Juan B. Justo 4302, B7608FDQ Mar del Plata, Argentina., Waiman CV; Instituto de Química del Sur (INQUISUR), CONICET-Departamento de Química, Universidad Nacional del Sur (UNS), Avenida Alem 1253, Bahía Blanca, 8000, Argentina., Arenas GF; LASER Laboratory-ICYTE-UNMDP-CONICET, Avenida J. B. Justo 4302, B7608FDQ Mar del Plata, Argentina., Ceolín M; INIFTA, UNLP-CONICET, Diagonal 113 y 64, CP 1900 La Plata, Argentina., Giovanetti LJ; INIFTA, UNLP-CONICET, Diagonal 113 y 64, CP 1900 La Plata, Argentina., Ramallo-López JM; INIFTA, UNLP-CONICET, Diagonal 113 y 64, CP 1900 La Plata, Argentina., Eliçabe G; Nanostructured Polymer Division, INTEMA, UNMDP-CONICET, Avenida Juan B. Justo 4302, B7608FDQ Mar del Plata, Argentina., Hoppe CE; Nanostructured Polymer Division, INTEMA, UNMDP-CONICET, Avenida Juan B. Justo 4302, B7608FDQ Mar del Plata, Argentina.
Jazyk:	angličtina
Zdroj:	Langmuir : the ACS journal of surfaces and colloids [Langmuir] 2020 Nov 24; Vol. 36 (46), pp. 13998-14008. Date of Electronic Publication: 2020 Nov 10.
DOI:	10.1021/acs.langmuir.0c02528
Abstrakt:	The photothermal response of mercaptoundecanoic acid (MUA)-coated Ag nanoparticles (Ag@MUA NPs) in both aqueous dispersions and paper substrates was determined as a function of pH when irradiated with a green laser or a blue LED source. Aqueous dispersions of Ag@MUA NPs showed an aggregation behavior by acidification that was used for the formation of NPs clusters of variable sizes. Aggregation was induced by changing the pH across the apparent p K a of the acid, higher than the p K a of the free acid. Formation of these aggregates was completely reversible allowing the return to the well-dispersed initial state by simply increasing the pH by the addition of a base. Aggregation produced a shift of the plasmon band that changed the spectra of the dispersions and their ability to be remotely heated when irradiated with visible light. These aggregates could be transferred to paper by simple impregnation of the substrates with the dispersion. On the solid substrate, a higher photothermal response than in the liquid medium was observed. A high local increase of up to 75 °C could be recorded on paper after only 30 s of irradiation with a green laser, whereas a blue LED array was enough for inducing the melting of a solid paraffin ( T m = 36-38 °C) deposited on it. This work demonstrates that photothermal heating can be controlled by the reversible aggregation of NPs to induce different thermal responses in liquid and solid media.
Databáze:	MEDLINE
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