RESUMEN
Multifunctional lanthanide-doped upconversion nanoparticles (UCNPs) have spread their wings in the fields of flexible optoelectronics and biomedical applications. One of the ongoing challenges lies in achieving UCNP-based nanocomposites, which enable a continuous-wave (CW) laser action at ultralow thresholds. Here, gold sandwich UCNP nanocomposites [gold (Au1)-UCNP-gold (Au2)] capable of exhibiting lasing at ultralow thresholds under CW excitation are demonstrated. The metastable energy-level characteristics of lanthanides are advantageous for creating population inversion. In particular, localized surface plasmon resonance-based electromagnetic hotspots in the nanocomposites and the huge enhancement of scattering coefficient for the formation of coherent closed loops due to multiple scattering facilitate the process of stimulated emissions as confirmed by theoretical simulations. The nanocomposites are subjected to stretchable systems for enhancing the lasing action (threshold â¼ 0.06 kW cm-2) via a light-trapping effect. The applications in bioimaging of HeLa cells and antibacterial activity (photothermal therapy) are demonstrated using the newly designed Au1-UCNP-Au2 nanocomposites.
Asunto(s)
Antibacterianos/farmacología , Nanopartículas del Metal/química , Nanocompuestos/química , Antibacterianos/química , Antibacterianos/efectos de la radiación , Dimetilpolisiloxanos/química , Erbio/química , Erbio/efectos de la radiación , Escherichia coli/efectos de los fármacos , Fluoruros/química , Fluoruros/efectos de la radiación , Oro/química , Oro/efectos de la radiación , Grafito/química , Células HeLa , Humanos , Hipertermia Inducida/métodos , Rayos Láser , Nanopartículas del Metal/efectos de la radiación , Pruebas de Sensibilidad Microbiana , Nanocompuestos/efectos de la radiación , Staphylococcus aureus/efectos de los fármacos , Resonancia por Plasmón de Superficie , Iterbio/química , Iterbio/efectos de la radiación , Itrio/química , Itrio/efectos de la radiaciónRESUMEN
FePt nanoparticles (NPs) have recently been revealed to be significant multifunctional materials for the applications of biomedical imaging, drug delivery and magnetic hyperthermia due to their novel magnetic properties. In this study, a newly discovered photothermal effect activated by the near infrared (NIR) femtosecond laser for FePt NPs was demonstrated. The threshold laser energy to destroy cancer cells was found to be comparable to that of gold nanorods (Au NRs) previously reported. Through the thermal lens technique, it was concluded that the temperature of the FePt NPs can be heated up to a couple of hundreds degree C in picoseconds under laser irradiation due to the excellent photothermal transduction efficiency of FePt NPs. This finding boosts FePt NPs versatility in multifunctional targeted cancer therapy.