Spatiotemporal Temperature Distribution of NIR Irradiated Polypyrrole Nanoparticles and Effects of pH

Omar Peñuñuri-Miranda, Miguel Olivas-Martinez, José Alberto Ibarra-Espinoza, Rosalva Josefina Rodríguez-Córdova, Karol Yesenia Hernández-Giottonini, Daniel Fernández-Quiroz, Paul Zavala-Rivera, Armando Lucero-Acuña*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The spatiotemporal temperature distributions of NIR irradiated polypyrrole nanoparticles (PPN) were evaluated by varying PPN concentrations and the pH of suspensions. The PPN were synthesized by oxidative chemical polymerization, resulting in a hydrodynamic diameter of 98 ± 2 nm, which is maintained in the pH range of 4.2–10; while the zeta potential is significantly affected, decreasing from 20 ± 2 mV to −5 ± 1 mV at the same pH range. The temperature profiles of PPN suspensions were obtained using a NIR laser beam (1.5 W centered at 808 nm). These results were analyzed with a three-dimensional predictive unsteady-state heat transfer model that considers heat conduction, photothermal heating from laser irradiation, and heat generation due to the water absorption. The temperature profiles of PPN under laser irradiation are concentration-dependent, while the pH increase only induces a slight reduction in the temperature profiles. The model predicts a value of photothermal transduction efficiency ((Formula presented.)) of 0.68 for the PPN. Furthermore, a linear dependency was found for the overall heat transfer coefficient ((Formula presented.)) and (Formula presented.) with the suspension temperature and pH, respectively. Finally, the model developed in this work could help identify the exposure time and concentration doses for different tissues and cells (pH-dependent) in photothermal applications.

Original languageEnglish
Article number3151
Issue number15
StatePublished - Aug 2022

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  • NIR laser irradiation
  • overall heat transfer coefficient
  • photothermal modeling
  • photothermal transduction efficiency
  • polypyrrole nanoparticles


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