Shape-dependent enzyme-like activity of Co3O4 nanoparticles and their conjugation with his-tagged EGFR single-domain antibody.

In this study, Co3O4 nanopolyhedrons, nanocubes, nanoplates and nanorods were synthesized and characterized. Furthermore, the peroxidase- and catalase-like activities of these Co3O4 nanoparticles (NPs) were studied and influence of the exposed crystal planes was explored. According to their morphology and peroxidase-like activity, dimercaptosuccinic acid (DMSA) modified Co3O4 nanopolyhedrons synthesized via coprecipitation method (Co3O4 NHs) were selected as a proper candidate for the immunohistochemical (IHC) detection of epidermal growth factor receptor (EGFR) expression in non-small cell lung cancer (NSCLC) tissues. Bivalent cobalt ions were coupled to the carboxyls on the surface of the obtained Co3O4 NHs so as to chelate the hexahistidine residues (His-Tags) at the C-terminal of EGFR single-domain antibodies (EGFR sdAbs). Finally, the as-obtained EGFR sdAbs-binding Co3O4 NHs (Co3O4 nanoprobes) were successfully applied to the detection of EGFR expression in NSCLC tissues.

Polyethyleneimine-functionalized iron oxide nanoparticles for systemic siRNA delivery in experimental arthritis.

AIMS: This study aimed to examine the efficacy of a nanocarrier (polyethyleneimine [PEI]-superparamagnetic iron oxide nanoparticle [SPIO]), composed of a core of iron oxide and a shell of PEI, in the systemic delivery of therapeutic siRNA to experimental arthritic joints. MATERIALS & METHODS: PEI-SPIO/siRNA nanoparticles were synthesized and characterized in vitro. Nanoparticles were administered intravenously to arthritic rats to analyze cellular uptake, tissue distribution and the therapeutic effect of a siRNA against the IL-2/-15 receptor ß chain (IL-2/IL-15Rß). RESULTS: PEI-SPIOs loaded with siRNA displayed negligible cytotoxicity, improved siRNA stability, efficient uptake by macrophages and the ability to induce specific gene silencing in vitro. PEI-SPIO-delivered siRNA accumulated easily in inflamed joints and was efficiently taken up by joint macrophages and T cells. Although IL-2/IL-15Rß siRNA-loaded PEI-SPIOs alone were efficacious in the treatment of experimental arthritis, combination therapy with both PEI-SPIO/IL-2/IL-15Rß siRNA and a magnetic field displayed an additive anti-inflammatory effect. CONCLUSION: PEI-functionalized SPIOs can be employed for systemic siRNA delivery in rheumatoid arthritis and enhanced therapeutic benefit can be achieved by the use of an external magnetic field.

Co3O4 nanoparticles with multi-enzyme activities and their application in immunohistochemical assay.

Co3O4 nanoparticles (Co3O4 NPs), synthesized by the coprecipitation method, showed intrinsic catalase-like, peroxidase-like, and SOD-like activity. The catalytic activity of Co3O4 NPs was much higher than analogous Fe3O4 NPs. Co3O4's mechanisms of catalytic activity were analyzed in detail using the electron spin resonance (ESR) method, which confirmed that Co3O4 NPs don't follow the classical Fenton reactions with hydrogen peroxide the way Fe3O4 NPs do. The high redox potential of Co(3+)/Co(2+) was supposed to be the leading cause of the differences in both activity and mechanism with Fe3O4. Based on the high, peroxidase-like activity, a new immunohistochemical assay was designed in which the avastin antibody was conjugated onto the surface of Co3O4 NPs. The conjugates obtained were used to detect vascular endothelial growth factor (VEGF) that was overexpressed in tumor tissue. When the experimental and control groups were stained, there were clear distinctions between them. This study showed that there are many opportunities to improve the enzyme-like activities of nanomaterials and also to improve their potential applications for biocatalysis and bioassays, especially in relatively harsh conditions.