CuCoFe Layered double hydroxides as laccase mimicking nanozymes for colorimetric detection of pheochromocytoma biomarkers

LDHzyme-assisted high-performance on-site tracking of levodopa pharmacokinetics for Parkinson's disease management

Parkinson's disease (PD) is a progressive neurodegenerative disorder marked by the loss of dopaminergic neurons and the consequent decline in motor and cognitive functions. The primary therapeutic agent levodopa necessitates precise dosing due to its narrow therapeutic window and complex pharmacokinetics. This study presents the development of a novel CuCoFe-LDHzyme-based sweat sensor for real-time monitoring of levodopa concentration in PD patients. Employing differential pulse voltammetry (DPV) technique, the sensor demonstrates high sensitivity and selectivity, achieving a detection limit of 28.1 nM. The sensor's design allows for non-invasive, continuous monitoring, significantly enhancing patient convenience compared to traditional blood sampling methods. Through pH correction, precise quantification of levodopa in sweat is accomplished, and a strong correlation (Pearson coefficient = 0.833) with blood levodopa levels is established. The pharmacokinetic profile of levodopa is reconstructed in real-time, offering a promising tool for optimizing PD treatment regimens. This study highlights the potential of CuCoFe-LDHzyme sensors to advance personalized treatment strategies, aiming to improve the quality of life for PD patients by providing clinicians with real-time data for medication adjustments.

Single-atom Fe nanozymes with excellent oxidase-like and laccase-like activity for colorimetric detection of ascorbic acid and hydroquinone

Although traditional Fe-based nanozymes have shown great potential, generally only a small proportion of the Fe atoms on the catalyst's surface are used. Herein, we synthesized single-atom Fe on N-doped graphene nanosheets (Fe-CNG) with high atom utilization efficiency and a unique coordination structure. Active oxygen species including superoxide radicals (O2•-) and singlet oxygen (1O2) were efficiently generated from the interaction of the Fe-CNG with dissolved oxygen in acidic conditions. The Fe-CNG nanozymes were found to display enhanced oxidase-like and laccase-like activity, with Vmax of 2.07 × 10-7 M∙S-1 and 4.54 × 10-8 M∙S-1 and Km of 0.324 mM and 0.082 mM, respectively, which is mainly due to Fe active centers coordinating with O and N atoms simultaneously. The oxidase-like performance of the Fe-CNG can be effectively inhibited by ascorbic acid (AA) or hydroquinone (HQ), which can directly obstruct the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Therefore, a direct and sensitive colorimetric method for the detection of AA and HQ activity was established, which exhibited good linear detection and limit of detection (LOD) of 0.048 μM and 0.025 μM, respectively. Moreover, a colorimetric method based on the Fe-CNG catalyst was fabricated for detecting the concentration of AA in vitamin C. Therefore, this work offers a new method for preparing a single-atom catalyst (SAC) nanozyme and a promising strategy for detecting AA and HQ.

Advances of Layered Double Hydroxide-Based Materials for Tumor Imaging and Therapy

Layered double hydroxides (LDH) are a class of functional anionic clays that typically consist of orthorhombic arrays of metal hydroxides with anions sandwiched between the layers. Due to their unique properties, including high chemical stability, good biocompatibility, controlled drug loading, and enhanced drug bioavailability, LDHs have many potential applications in the medical field. Especially in the fields of bioimaging and tumor therapy. This paper reviews the research progress of LDHs and their nanocomposites in the field of tumor imaging and therapy. First, the structure and advantages of LDH are discussed. Then, several commonly used methods for the preparation of LDH are presented, including co-precipitation, hydrothermal and ion exchange methods. Subsequently, recent advances in layered hydroxides and their nanocomposites for cancer imaging and therapy are highlighted. Finally, based on current research, we summaries the prospects and challenges of layered hydroxides and nanocomposites for cancer diagnosis and therapy.

N-doped carbon Co/CoOx with laccase-like activity for detection of epinephrine

N-doped carbon Co/CoOx with laccase-like activity was directionally designed by pyrolyzing Co-coordination polymer and applied to detect epinephrine, which revealed a new preparation strategy for laccase mimics. The formation mechanism of the N-doped carbon Co/CoOx nanozyme was reconnoitered by a thermogravimetric-mass spectrometry system (TG-MS). N-doped carbon Co/CoOx exhibited outstanding laccase-like activity, and the Michaelis-Menten constant and maximum initial velocity were calculated to be 0.087 mM and 0.0089 μM s-1, respectively. Based on this principle, a simple colorimetric sensing platform was developed for the quantitative detection of epinephrine, which can be used to diagnose pheochromocytoma. In addition, the visual platform for detecting epinephrine exhibited a linear range of 3 to 20 μg mL-1 and a calculated detection limit of 0.42 μg mL-1. Therefore, the proposed colorimetric sensing platform is a promising candidate to be applied in precise early pheochromocytoma diagnosis.

A bioinspired copper-based coordination polymer for the detection of pheochromocytoma biomarkers

Oxidase-mimicking (catechol oxidase/laccase) nanozymes provide outstanding specificity in the detection of epinephrine (Epi) for the assessment of pheochromocytoma; however, epinephrine (Epi) and norepinephrine (NE) co-existing in the same systems will reduce the selectivity of the biosensor. In the current study, we synthesized copper-based coordination polymer (Cu-CP) nanozymes capable of accelerating the oxidation of Epi with high specificity. Furthermore, the Cu-CP is able to detect Epi over a wide linear range of 0.5-100 μM with a low detection limit of 0.36 μM while providing excellent stability and recyclability. Furthermore, we employed colorimetric and fluorescence signals for sequential detection of the coexistence of Epi and NE for use in tracking the treatment outcomes of patients with pheochromocytoma. Experiments using artificial urine further confirmed the efficacy of the proposed system.