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Abstract: Calmodulin (CaM) is a ubiquitous protein in eukaryotic cells, and it plays an important role in cancer progression. In this paper, a highly sensitive immunosensor adopting a dual-layered enzyme strategy was proposed for electrochemical detection of CaM. This immunosensor was constructed by introducing honeycomb-like mesoporous carbon (HMPC) as a sensor platform to sequentially immobilize antibody (Ab1), CaM and a multi-functionalized label. The label (HRP-PAupc-Ab1) was synthesized by covalently binding Ab1 and horseradish peroxidase (HRP) to poly(acrylic acid)-functionalized Au popcorn (PAupc) nanoparticles. A novel dual-layered enzyme strategy was employed by incubating HRP-secondary antibody (HRP-Ab2) onto the label surface and the enhanced biocatalyzed precipitation was therefore induced. This immunosensor exhibited satisfactory analytical performances for CaM detection with a linear response ranging from 5.0pgmL−1 to 100ngmL−1 and a detection limit of 1.5pgmL−1. The immunosensor has also been successfully applied to the CaM analysis in two cancer cells (HepG2 and MCF-7) with high sensitivity, which has shown great potency for cancer study. [Copyright &y& Elsevier]

Abstract The redox balance in cellular mitochondria is closely related to the physiological and pathological processes of the body. When exposed to external stimuli, the redox state in cells changes dynamically, and presents cell heterogeneity, which creates a need for techniques that can make dynamic and reversible visual analysis of redox in mitochondria at single-cell level. Here we describe a method for single-cell redox analysis based on a microfluidic device combing with a reversible fluorescent probe (Cy-O-ebselen), that enables online culture, labelling and dynamic fluorescent imaging analysis of mitochondrial redox (H 2 O 2 /GSH) change. Using this method, we further explored the dynamic changes of mitochondrial redox state after thermal stimulation or combined thermal-drug stimulation, and analysed the heterogeneous response of cells to external stimuli at the single cell level. Highlights • A method based on a microfluidic device for single-cell redox analysis is proposed. • The method allows dynamic flourescent imaging of mitochondrial redox state. • Heterogeneous response of single cells to external stimuli is explored. [ABSTRACT FROM AUTHOR]