Enhancing the Plasmon Resonance Absorption of Multibranched Gold Nanoparticles in the Near-Infrared Region for Photothermal Cancer Therapy: Theoretical Predictions and Experimental Verification

Abstract

Multibranched gold nanoparticles (M-AuNPs) can serve as photothermal agents for near-infrared (NIR) photothermal therapy (PTT) of cancer, but a major shortcoming is that they tend to strongly scatter NIR light, causing a significant reduction in absorption. This work addresses this issue, based on theoretical simulations and experimental determinations, to enhance the absorption and reduce the scattering of these materials by screening their structural parameters. Our finite-difference time-domain simulations predict that M-AuNPs with a core size of ∼25 nm, a tip number of 5, and a tip height of ∼40 nm (i.e., an aspect ratio of ∼2) are optimal for trapping NIR light and yielding the highest light-to-heat conversion efficiency (η) and for trapping NIR light of various polarization and incident directions. The predicted M-AuNPs were synthesized by a seed-mediated growth method, and the measured optical properties agreed well with the simulation results. The M-AuNPs were further used as photothermal agents for in vitro killing of MCF-7 cells and in vivo ablation of tumors constructed on nude mice. Nearly all cells died after they were incubated with M-AuNPs and irradiated under an 808 nm laser at a 1.0 W cm–2 for 10 min. The tumors on the nude mice were also effectively ablated without regrowth during the observation period (20 days) after PTT.

Plasmonic SERS Biosensor Based on Multibranched Gold Nanoparticles Embedded in Polydimethylsiloxane for Quantification of Hematin in Human Erythrocytes

“…In the synthesis, DMF is a weak reducing agent for the reduction of Au 3+ to Au + ions, and thus, PVP behaved as both the reducing agent, to further reduce the generated Au + to Au 0 , and the stabilizing agent for the produced Au 0 . Moreover, PVP can guide the anisotropic growth of Au 0 on the surface of the Au seeds to produce M-AuNPs by preferentially adsorbing on the (111) faces of the Au seeds and inhibiting further deposition of Au 0 atoms on these faces . Therefore, the morphology of the M-AuNPs can be tailored by PVP and the concentrations of the Au seeds.…”

“…M-AuNPs were synthesized by a seed-assisted growth method using poly­(vinylpyrrolidone) (PVP) and N , N -dimethylformamide (DMF) as reducing agents. , Au seeds, with a diameter of ∼15 nm, were synthesized by reducing AuCl 4 – with sodium citrate, according to a slightly modified published procedure . Typically, in a condenser-equipped round-bottom flask (250 mL), 100 mL of HAuCl 4 (0.01 wt %) was first heated to boiling under vigorous stirring, followed by the rapid introduction of sodium citrate (3 mL, 1 wt %), causing a color change from pale yellow to burgundy.…”

“…Here, we report a plasmonic surface-enhanced Raman scattering (SERS) biosensor method to address this challenge. This method exploits the strong plasmon coupling features of multibranched gold nanoparticles (M-AuNPs) and their tunable localized surface plasmon resonance (LSPR) characteristics, where the former results in a strong electric field, E -field, and enables an enormous enhancement of the Raman signals, − while the latter can be tuned to the near-infrared region (NIR) to facilitate biological analysis. , The hematin (or hematin-containing hemolysates) is first deposited on an Au film surface and then simply covered with M-AuNP-embedded polydimethylsiloxane (PDMS) (see the biosensor configuration in Figure ). Upon irradiation with a 785 nm laser, strong SERS signals are generated owing to the transparent and flexible features of the PDMS film, which provides the M-AuNPs with close contact with the target surface, and plasmon coupling between the M-AuNPs and the Au film .…”

Recent applications of cell-penetrating peptide guidance of nanosystems in breast and prostate cancer (Review)

“…Similarly, nanoliposomes possess a specific characteristic of carrying both hydrophobic and hydrophilic drugs due to their double lipid membrane ( 25 , 26 ). Metallic NPs can serve as theranostics by carrying anticancer drugs and taking advantage of surface plasmon resonance for photothermal therapy and imaging ( 27 , 28 ). On another approach, nanoliposomes were used to develop a synthetic vaccine particle carryng rapamycin (SVP-rapamycin), with the objective of inducing a tolerogenic immune profile to NPs ( 29 ).…”

Engineering Colloidal Lithography and Nanoskiving to Fabricate Rows of Opposing Crescent Nanogaps

“…[ 10–12 ] A currently fast developing area in plasmonics is metal nanoparticles. They have great applications in sensing, [ 13 ] imaging, [ 14 ] catalysis, [ 14–17 ] biomedicine, [ 18,19 ] etc. In particular, asymmetric nanoparticles have unique optical properties, which are different from their normal symmetrical nanostructures.…”