Emerging Biomedical Applications of Enzyme-Like Catalytic Nanomaterials

Abstract

Nanomaterials have been developed for many biomedical applications, including medical imaging, drug delivery, and antimicrobial coatings. Intriguingly, nanoparticles can display 'enzyme-like' activity and have been explored as alternatives to natural enzymes in several industrial and energy-related applications. Recently, these catalytic nanomaterials with enzyme-mimetic properties have found new biomedical applications, from biofilm disruption to protection against neurodegeneration and tumor prevention. In this review we focus on recent in vivo studies demonstrating potential therapeutic uses of catalytic nanomaterials. We also provide insights about the relationships between catalytic activity, therapeutic efficacy, and biocompatibility that are critical for clinical translatability. Finally, we discuss current challenges and future directions for the use of these nanomaterials as novel platforms for the development of sustainable, affordable, and safe therapeutics.

Keywords: biofilm; cancer; catalysis; enzyme mimetics; imaging; nanoparticles.

Figure 1. Catalytic nanoparticles for diagnostics

(A) Magnetoferritin nanoparticles for targeting and visualizing tumor tissues. (B) Histology staining using M-HFn, hydrogen peroxide and DAB identified tumor tissue via brown staining (left) as confirmed by FITC-HFn fluorescence microscopy. (C) Nanozyme-strip for rapid local diagnosis of Ebola. Detection of Ebola virus in human serum at various concentrations using immunochromatographic strips based on (D) MNPs or (E) AuNP. The asterisk indicates the limit of visual detection of the test. Figure adapted with permission from references [56, 58].

Figure 2. Nanocatalysis promotes biofilm disruption and prevention of tooth decay in vivo.

(A) Schematic depiction of the anti-biofilm effects of CAT-NP. (B) Images of teeth from a rat model, treated as noted. Arrowheads indicate severity of tooth decay caused by biofilms (green: initial lesions, blue: moderate lesions, red: severe lesions with cavitation). (C) Quantification of lesions in the different treatment groups (Keyes scoring is a method for simultaneous classification and quantification of the number and severity of caries lesions). Figure adapted with permission from reference [19].

Figure 3. Iron oxide nanoparticles inhibit tumor growth by inducing pro-inflammatory macrophage polarization in tumor tissues

Mice were either injected with cancer cells alone (A) or injected with cancer cells four days after treatment with iron oxide nanoparticles (B). (C) and (D) In vivo optical imaging of the tumor cells (which express luciferase) indicate that treatment with ferumoxytol reduces tumor growth compared to control. Figure adapted with permission from reference [22].

Figure 4. Cerium oxide (ceria) nanoparticles reduce injury caused by stroke

(A) Histology sections from a rat model of stroke where ceria were administered after the stroke. (B) Quantification of stroke volumes from the different treatment groups. (C) Ceria treatment reduced TUNEL staining, a marker of cell death. (D) Ceria treatment (light gray) reduced lipid peroxide content in the stroke area compared to control (dark gray). Figure adapted with permission from reference [71].

Figure I, Key Figure

Schematic depicting the properties and actions of enzyme-mimicking nanoparticles.

Figure I

Diagram indicating the requirements for a clinically translatable catalytic nanoparticle agent.