Emerging Nanomaterials as Versatile Nanozymes: A New Dimension in Biomedical Research

Single-well colorimetric sensor array for discrimination and smartphone-assisted detection of catecholamines based on Fe-carbon dots nanozymes

BACKGROUND

Catecholamines (CAs), such as noradrenaline (NE), adrenaline (AD), and dopamine (DA), are essential signaling mediators that regulate various physiological functions. Monitoring their levels is crucial for studying and diagnosing diseases, as abnormal concentrations are associated with numerous health conditions. However, distinguishing between these CAs is challenging due to their highly similar molecular structures.

RESULTS

In this study, Fe-doped carbon dot-based nanozymes (Fe-CDs) with strong peroxidase-like activity were synthesized using a simple one-pot method. Fe-CDs-based sensing systems exhibit excellent stability, reproducibility, sensitivity (with detection limits of 26.6 nM for NE, 46.0 nM for AD, and 33.3 nM for DA), and anti-interference properties. A triple-channel single-well colorimetric sensor array was developed by collecting the absorbance at 20, 40, and 60 min as sensing units, enabling the effective differentiation and identification of various CAs.

SIGNIFICANCE

The Fe-CDs-based system has proven capable of detecting CAs in real human urine and fetal bovine serum. Additionally, the Fe-CDs-based smartphone-assisted platform provides efficient, highly sensitive, and on-site CAs detection, making it highly promising for biomedical and diagnostic applications.

Rational Design of Nanozymes for Engineered Cascade Catalytic Cancer Therapy

Nanozymes have shown significant potential in cancer catalytic therapy by strategically catalyzing tumor-associated substances and metabolites into toxic reactive oxygen species (ROS) in situ, thereby inducing oxidative stress and promoting cancer cell death. However, within the complex tumor microenvironment (TME), the rational design of nanozymes and factors like activity, reaction substrates, and the TME itself significantly influence the efficiency of ROS generation. To address these limitations, recent research has focused on exploring the factors that affect activity and developing nanozyme-based cascade catalytic systems, which can trigger two or more cascade catalytic processes within tumors, thereby producing more therapeutic substances and achieving efficient and stable cancer therapy with minimal side effects. This area has shown remarkable progress. This Perspective provides a comprehensive overview of nanozymes, covering their classification and fundamentals. The regulation of nanozyme activity and efficient strategies of rational design are discussed in detail. Furthermore, representative paradigms for the successful construction of cascade catalytic systems for cancer treatment are summarized with a focus on revealing the underlying catalytic mechanisms. Finally, we address the current challenges and future prospects for the development of nanozyme-based cascade catalytic systems in biomedical applications.

Au@Pt@Pd nanozymes based lateral flow immunoassay for quantitative detection of SARS-CoV-2 nucleocapsid protein in nasal swab samples

Three-metal-core-shell nanoparticles (Au@Pt@PdNPs) providing excellent peroxidase-like activity were applied in lateral flow immunoassay (LFIA), designated as Au@Pt@Pd-LFIA, for detecting the nucleocapsid protein (NP) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). An Au@Pt@Pd-LFIA was developed for quantitatively testing of SARS-CoV-2 NP with a range 0.12-31.25 ng/mL. The limit of detection (LOD) of Au@Pt@Pd-LFIA strip was 0.06 ng/mL, which was 16-fold or eightfold more sensitive than that of the gold lateral flow immunoassay (Au-LFIA) and the gold flower flow immunoassay (AF-LFIA) strips, respectively. For detection of clinical samples from nasal swabs using test strips, Au@Pt@Pd-LFIA had 84.09% sensitivity, 100% specificity, and 92.55% accuracy. In terms of detection time, the testing of Au@Pt@Pd-LFIA strip was 16 min similar to Au-LFIA (15 min) and AF-LFIA (10 min), but much shorter than ELISA (2 h). In conclusion, Au@Pt@Pd-LFIA is a sensitive, rapid, and simple test for quantitative detection of SARS-CoV-2 NP in nasal swab samples.