Photoresponsive Inorganic Nanomaterials in Oncology

Abstract

The diagnosis and treatment of cancer are continuously evolving in search of more efficient, safe, and personalized approaches. Therapies based on nanoparticles or physical stimuli-responsive substances have shown great potential to overcome the inherent shortcomings of conventional cancer therapies. In fact, nanoparticles may increase the half-life of chemotherapeutic agents or promote the targeting in cancer tissues while physical stimuli-responsive substances are more effective and safer with respect to traditional chemotherapeutic agents because of the possibility to be switched on only when needed. These 2 approaches can be combined by exploiting the ability of some inorganic nanomaterials to be activated by light, ultrasounds, magnetic fields, or ionizing radiations. Albeit the development of stimuli-responsive materials is still at the early stages, research in this field is rapidly growing since they have important advantages with respect to organic nanoparticles or molecular substances, like higher stability, and higher efficiency in converting the stimulus in heat or, in some cases, reactive oxygen species. On the other hand, the translation process is slowed down by issues related to safety and quality of the formulations. This literature review summarizes the current advancements in this research field, analysing the most promising materials and applications.

Keywords: carbon; magnetic hyperthermia; nanoparticles; noble metals; photodynamic therapy; photothermal therapy; radiotherapy; sonodynamic therapy.

Figure 1.

Trend in the scientific publications containing the words “inorganic nanoparticles” and “photothermal” or “photodynamic” or “magnetic hyperthermia” or “radiotherapy” or “sonodynamic” in the past 20 years (source Web of Science).

Figure 2.

Type of physical stimuli that can be used to induce cell death mediated by inorganic NPs. Abbreviation: NPs, nanoparticles.

Figure 3.

Pathways of cytotoxicity in SDT. Reprinted from Advanced Drug Delivery Review, Canaparo R, Foglietta F, Barbero N, Serpe L. The promising interplay between sonodynamic therapy and nanomedicine p. 114495, Copyright (2022), with permission from Elsevier. Abbreviation: SDT, sonodynamic therapy.

Figure 4.

Mechanisms of ROS and heat production in molecular substances. Abbreviation: ROS, reactive oxygen species.

Figure 5.

(A) Representative SEM images of HCNP; (B) colloidal suspension of HCNP in water; (C) and (D) photothermal activity of HCNP: (C) thermal camera image of colloidal suspension of HCNP in water after irradiation by NIR laser and (D) temperature change curves during NIR laser irradiation of HCNP; (E) internalization of HCNP: representative TEM image showing HCNP internalized by the human A549 lung adenocarcinoma cell line treated for 24 h with 80 µg/mL of HCNP; (F) and (G) effect of NIR-activated HCNP on A549 cells (irradiance 3 W/cm², 15 min): (F) cells irradiated by NIR laser and (G) cells exposed to HCNPs (80 μg/mL) and irradiated by NIR laser (HCNPs + NIR). Abbreviations: HCNP, hydrothermal carbonization; NIR, near-infrared; SEM, scanning electron microscope; TEM, transmission electron microscopy.