Biodegradable Inorganic Nanoparticles for Cancer Theranostics: Insights into the Degradation Behavior

Abstract

Inorganic nanoparticles as a versatile nanoplatform have been broadly applied in the diagnosis and treatment of cancers due to their inherent superior physicochemical properties (including magnetic, thermal, optical, and catalytic performance) and excellent functions (e.g., imaging, targeted delivery, and controlled release of drugs) through surface functional modification or ingredient dopant. However, in practical biological applications, inorganic nanomaterials are relatively difficult to degrade and excrete, which induces a long residence time in living organisms and thus may cause adverse effects, such as inflammation and tissue cysts. Therefore, the development of biodegradable inorganic nanomaterials is of great significance for their biomedical application. This Review will focus on the recent advances of degradable inorganic nanoparticles for cancer theranostics with highlight on the degradation mechanism, aiming to offer an in-depth understanding of degradation behavior and related biomedical applications. Finally, key challenges and guidelines will be discussed to explore biodegradable inorganic nanomaterials with minimized toxicity issues, facilitating their potential clinical translation in cancer diagnosis and treatment.

Materdicine: Interdiscipline of materials and medicine

“…In contrast, nanomaterials with large size ranging from 20 to 200 nm not only feature prolonged residence time in the body but also offer more opportunities to achieve their multifunctionality via modifying targeting ligands and loading drugs 159 . However, large‐sized nanoparticles are inclined to accumulate in RES, leading to potential toxic effects on biological system 160 . Therefore, one promising strategy is to engineer degradable nanoplatforms and nanoplatforms of appropriate size, which allow their sufficient time to perform the expected functions, and can also be decomposed into small‐sized degradation products that can be rapidly cleared from the body.…”

Two-Dimensional Theranostic Nanomaterials in Cancer Treatment: State of the Art and Perspectives

“…The large surface area of exfoliated MnO 2 NSs provided numerous anchoring points for DOX drug molecules, which were loaded onto the surface of nanosheets via electrostatic interaction and Mn-N coordination bonds. Meanwhile, the loaded cargos could be released very fast in an acidic microenvironment like a cancer tumor, based on the break-up of MnO 2 [112]. Owing to these properties, MnO 2 nanosheets assisted in the high accumulation of DOX within the cancer cells and time-dependent pH-responsive intracellular drug release.…”

“…Generally, inorganic nanomaterials are relatively challenging to degrade and excrete in biological applications. They have a long residence time in living organisms causing adverse effects, including inflammation and tissue cysts [112]. Hence, consideration of the biosafety profile of theranostic 2D nanomaterials is of great importance for their cancer treatment.…”

“…WS 2 NSs possess high stability and are hardly degraded in the physiological environment and hence retains in RES organs for a long time. TiS 2 NSs are unstable, and their gradual transformation into the water-insoluble TiO 2 aggregates slowly eliminates from the body [112,123]. As far as the toxicity of graphene-based nanomaterials is concerned, the sharp edges of graphene are the main contributor to its high cytotoxicity.…”

“…The free Mn 2+ ions exhibit an outstanding MRI contrast effect due to its five unpaired 3d electrons and hence poses a high relaxivity than that of MnO 2 nanoparticles. The degradation process of MnO 2 NSs can be monitored by MRI, due to the much-improved MRI contrast enhancement after decomposition [112]. The literature report reveals that the toxicity of Mn 2+ is much higher than that of MnO 2 NSs [103].…”