Noble Metal Nanoparticle-Based Photothermal Therapy: Development and Application in Effective Cancer Therapy

Abstract

Photothermal therapy (PTT) is a promising cancer therapy modality with significant advantages such as precise targeting, convenient drug delivery, better efficacy, and minimal adverse effects. Photothermal therapy effectively absorbs the photothermal transducers in the near-infrared region (NIR), which induces the photothermal effect to work. Although PTT has a better role in tumor therapy, it also suffers from low photothermal conversion efficiency, biosafety, and incomplete tumor elimination. Therefore, the use of nanomaterials themselves as photosensitizers, the targeted modification of nanomaterials to improve targeting efficiency, or the combined use of nanomaterials with other therapies can improve the therapeutic effects and reduce side effects. Notably, noble metal nanomaterials have attracted much attention in PTT because they have strong surface plasmon resonance and an effective absorbance light at specific near-infrared wavelengths. Therefore, they can be used as excellent photosensitizers to mediate photothermal conversion and improve its efficiency. This paper provides a comprehensive review of the key role played by noble metal nanomaterials in tumor photothermal therapy. It also describes the major challenges encountered during the implementation of photothermal therapy.

Keywords: combination therapy; noble metal nanomaterials; photothermal therapy; tumor therapy.

Figure 3

(A) Schematic illustration of the D/UCNP@cgAuNCs nanoassemblies for tumor microenvironment-enhanced ratiometric NIR-II fluorescence imaging and chemo-/photodynamic combination therapy [43]. Copyright 2023, American Chemical Society; (B) Schematic representation of the therapeutic processes of pH–enzyme–NIR multi-responsive immune-adjuvant nanoparticles (R837@MSNmannose-AuNPs-Glu/Lys, RMmAGL), which combines tumor-specific photothermal therapy and photothermal-assisted immunotherapy for malignant tumor therapy. GNP-VGB3 recognizes VEGFR1 and VEGFR2 and suppresses their VEGF-induced phosphorylation in endothelial cells [38]. Copyright 2023, Wiley-VCH GmbH.

Figure 4

(A) Schematic illustration of AgPCPP nanoparticles; (B) Heating and cooling curves of AgPCPP nanoparticles, free Ag₂S-NP and DI water under 10 min of irradiation (808 nm, 2 W cm⁻²); (C) Photostability of AgPCPP under four cycles of irradiation/cooling for a total duration of 20 min (808 nm, 2 W cm⁻²); (D) Infrared thermography of tumors treated with saline, Ag₂S-NP, and AgPCPP nanoparticles during 30 min of laser irradiation [61]. Copyright 2023, Wiley-VCH GmbH; (E) Schematic diagram of the synthesis of the HASAIC probe; (F) Temperature change at tumor site under laser irradiation after injection of PBS and probe, respectively; (G) Temperature changing curve of tumor site under laser irradiation after injection of PBS and probe [62]. Copyright 2021, Elsevier B.V. All rights reserved; (H) Schematic illustration of ligand passivation on the Ag₂S CQD surface; (I) On-off cycles of the photothermal effect with 500 nM CQDs under 1.5 W/cm² [64]. Copyright 2024, American Chemical Society.

Figure 1

Schematic representation of noble metal nanomaterials for use in cancer photothermal therapy.

Figure 2

Schematic illustration of synthesis (I) and therapeutic mechanism (II) of SFT-Au nanoparticles. The nanoparticles were able to utilize and manipulate the over-expressed calcium in the mitochondria of tumor cells for the simultaneous inhibition of malignant tumors via calcium-dependent photothermal therapy and mitochondrial calcification-mediated starving therapy [33]. Copyright 2023, Wiley-VCH GmbH.

Figure 5

(A) Schematic illustration of L/D-CAg@Au nanoparticles. (B) Calculation of the photothermal conversion efficiency at 808 nm. The orange curve represents the photothermal effect of the Ag@Au aqueous solution. The black line represents the time constant (τs) for the heat transfer of the system. (C) Heating and cooling curves of water, Ag@Au, L-CAg@Au, and D-CAg@Au aqueous dispersion (100 μg mL⁻¹) under the 808 nm laser on/off irradiation (1.0 W cm⁻²). (D) Infrared thermography of tumor sites exposed to 808 nm laser irradiation at 1.0 W cm⁻² for 10 min [13]. Copyright 2023, American Chemical Society. (E) Schematic Illustration of the Synthesis of AgNCs Using OCT as the Biotemplate and their application. (F) Photothermal heating curves of MKN-45 tumors under 1270 nm laser after intravenous injection of DNA-Ag@Pd NCs for 6 h [63]. Copyright 2023, Wiley-VCH GmbH. (G) Schematic illustration of the Synthesis of DNA-templated Ag@Pd alloy nanoclusters (DNA-Ag@Pd NCs). (H) The temperature elevation profiles of AgNP and AgNC solutions at the same concentration under laser irradiation and the photothermal images of the AgNCs solution at different time intervals irradiated. (I) In vivo thermal images of mice injected with saline or the AgNCs under NIR laser irradiation and tumor temperature profiles as the function of laser irradiation time [65]. Copyright 2018, American Chemical Society.

Figure 6

(A) Schematic illustration of the formation of AuPtAg-GOx nanozyme. (B) The mechanism for tumor immunotherapy induced by starvation therapy-augmented mild photothermal therapy. (C,F) Temperature changes of AuPtAg at different concentrations under 808 nm and 1064 nm laser irradiation (0.5 W cm⁻², 5 min). (D,G) Temperature changes of AuPtAg (1000 μg mL⁻¹) with various laser power densities (808 nm laser (D) and 1064 nm laser (G) for 5 min). (E,H) Plot of cooling time versus negative natural logarithm of the temperature driving force (808 nm laser (E) and 1064 nm laser (H)). (I) Representative flow cytometer plots of M2-type macrophages (CD206+), and M1-type macrophages (CD86+) in TAMs (F4/80+) and the secretion levels of IL-10, IL-12 in the supernatant after different therapies. Groups: (1) control, (2) AuPtAg-GOx, (3) AuPtAg-PEG + 1064 nm (0.5 W cm⁻²), (4) AuPtAg-GOx + 1064 nm (0.5 W cm⁻²). Statistical significance is assessed by an unpaired Student’s two-sided t-test. * p < 0.05, ** p < 0.01 [71].

Figure 7

(A) Schematic illustration of synthesizing AgPd@BSA/DOX and antitumor mechanism [76]. Copyright 2020, Elsevier B.V. (B) Schematic illustration of MoO_3−x-Ag-PEG-MnO₂ preparation process and therapeutic mechanism [77]. Copyright 2023, Elsevier Inc. (C) Schematic illustration for Enzyme coordination interactions between GOx and MOFs, the modification of AgNPs, and the antitumor mechanism [78]. Copyright 2021, Elsevier B.V.