The chemical redox modulated switch-on fluorescence of carbon dots for probing alkaline phosphatase and its application in an immunoassay

Abstract

Early diagnosis is an important requirement for the early treatment of diseases and reliable detection methods for biomarkers are indispensable tools for early diagnosis. However, recent innovations in analytical technology are rarely employed widely due to multiple factors including the requirement of specialized equipment and infrastructures. Hence, much attention has been focused on exploring universal nanoprobes for routine practices. Here, we report a chemical redox modulated switch-on fluorescence strategy based on versatile carbon dots (CDs) for probing alkaline phosphatase (ALP) and human IgG (a model target). The fluorescence of the CDs is initially quenched by Fe(III) and then restored by ascorbic acid, which is generated from the hydrolysis of ascorbic acid 2-phosphate (AAP) by the catalysis of ALP. Based on that, a simple "switch-on" fluorescence assay for ALP was designed and leads to a sensitivity of as low as 0.8 U L À1. The proposed assay is applied in ALP sensing in human serum samples. Additionally, the application of the switch-on fluorescence strategy is successfully expanded to the immunoassay of human IgG in serum from healthy adults and patients with systemic lupus erythematosus. The developed sensing system could be devised for various target sensors and has promising potential in the field of biological analysis and clinical diagnostics.

DNA-damage and cell cycle arrest initiated anti-cancer potency of super tiny carbon dots on MCF7 cell line

“…The HR-TEM image (inset in Fig. 1) shows that the CDs displayed a highly crystalline structure with a 0.21 nm lattice spacing that is attributed to the graphitic (sp 2 ) carbon 84 . Surface ζ-potential of − 23.5 ± 6.21 mV which could be the sign of a surface with the higher density of oxygen-rich groups 74,75 .…”

Preparation of Anti-Aristolochic Acid I Monoclonal Antibody and Development of Chemiluminescent Immunoassay and Carbon Dot-Based Fluoroimmunoassay for Sensitive Detection of Aristolochic Acid I

“…As a novel fluorescent probe, the carbon dots (CDs) exhibit superiority of remarkable fluorescent properties, simple preparation, good biocompatibility, and easy functionalization [28], which can be employed for FIA. For FIA development, most previous publications reported a phosphate-triggered method to recover the fluorescence of CDs [29][30][31]. Nevertheless, alkaline phosphatase (ALP) activity requires more than 30 min for the catalyst, which is not satisfactory.…”

Multiresponsive Fluorescence “Turn ON–OFF” Switch on PB@EuW10/SiO2 Composite for Dual Spectral Detection of N2H4 and H2O2

“…In recent years, fluorescence switching systems based on fluorescent materials have attracted much interest in diverse applications, including sensor, optics, and biological imaging, − owing to their excellent photoluminescence properties. Different kinds of fluorescence materials have been developed in the switch application, such as polymers, organic aggregates, organic/inorganic hybrids, and nanocomposites. − For instance, Yang and co-workers synthesized N,S-co-doped red-emitting carbon dots (R-CDs) based on which a fluorescent switch is explored for the rapid identification and quantification of Fe 3+ ions and l -Cys .…”