Tuning the photothermal effect of carboxylated-coated silver nanoparticles through pH-induced reversible aggregation
- Cativa, Nancy Maribel
- Dell'Erba, Ignacio Esteban
- Waiman, Carolina Vanesa
- Arenas, Gustavo Francisco
- Ceolin, Marcelo Raul
- Giovanetti, Lisandro Jose
- Ramallo Lopez, Jose Martin
- Elicabe, Guillermo Enrique
- Hoppe, Cristina Elena
DOIAbstract
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 pKa of the acid, higher than the pKa 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 th...
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