Label-free electrochemical immunosensor for Ochratoxin a detection in coffee samples.

Ochratoxin A (OTA) is a nephrotoxic and carcinogenic mycotoxin frequently found in coffee, which directly impacts human health and the economy of many countries. For this reason, there has been a growing need for simple and sensitive tools for the on-site detection of this mycotoxin. In this study, we developed a label-free impedimetric immunosensor to detect OTA. The biosensor was built on a thin-film gold electrode evaporated on glass substrtes, modified with a self-assembled cysteamine monolayer and anti-OTA antibodies. Atomic force microscopy and Microspectroscopy RAMAN confirmed the successful functionalization of the electrodes. The biosensor performance was evaluated by electrochemical impedance spectroscopy and the measurements indicated a linear relationship between the change in the impedance values and the OTA concentration in the range from 0.5 to 100 ng mL-1 with a limit of detection of 0.15 ng mL-1. The biosensor was highly selective and did not suffer matrix interference when analyzed in coffee samples. Furthermore, considering the small sample volumes, the short time required for analysis, and the possibility of miniaturization, the developed biosensor represents a promising analytical device for on-site coffee quality analyses.

Near-Infrared Photoactive Theragnostic Gold Nanoflowers for Photoacoustic Imaging and Hyperthermia.

Branched anisotropic gold nanostructures present distinguished performance acting both as contrast agents for photoacoustic imaging and as active agents for photothermal therapies. Despite advances in their fabrication methods, the synthesis of such gold nanomaterials in a simple and reproducible way is still a challenge. In this paper, we report the development of branched anisotropic gold nanoparticles, the so-called gold nanoflowers (AuNFs), as near-infrared active theragnostic materials for cancer therapy and diagnosis. In situ chemical synthesis of the AuNFs was optimized to obtain monodisperse nanoflowers with controllable size and optical properties. Upon varying the temperature and gold ion concentrations, it was possible to tune the optical activity of the nanoparticles from 590 to 960 nm. The AuNFs exhibited good stability in the cell culture medium, and under laser irradiation. Photoacoustic imaging revealed that the NFs could be imaged in phantom systems even at low concentrations. In vitro tests revealed that the nanoflowers were effective in the photothermal therapy of a rat hepatocarcinoma (HTC) cell lineage. In addition, no toxicity was observed to mouse fibroblast (FC3H) cells incubated with the AuNFs. Our results reveal a simple method to synthesize branched anisotropic gold nanostructures, which is a promising platform for photothermal and photoacoustic therapies.

Photothermia and Activated Drug Release of Natural Cell Membrane Coated Plasmonic Gold Nanorods and ß-Lapachone.

Plasmonic gold nanoparticles present extraordinary potential for near-infrared photothermal and triggered-therapeutic release treatments of solid tumors. In this study, we create a multifunctional nanocarrier in which PEG-coated gold nanorods are grouped into natural cell membrane vesicles (CM) from lung cancer (A549) cells and loaded with ß-lapachone (CM-ß-Lap-PEG-AuNRs). ß-Lapachone (ß-Lap) is an anticancer agent activated by the enzyme NADP(H):quinine oxidoreductase (NQO1), commonly found at higher levels in cancer cells. The irradiation with near-infrared (NIR) laser leads to disruption of the vesicles and release of the PEG-AuNRs and ß-Lap. The system presents an enhanced in vitro cytotoxicity against A549 cancer cells, which can be attributed to the specific cytotoxicity of ß-Lap combined with heat generated by laser irradiation of the AuNRs. In agreement, in vivo treatment with CM-ß-Lap-PEG-AuNRs and irradiation shows a histopathological recovery from nonmuscle invasive bladder cancer of most of the animals with only one cycle of application and irradiation. Such multifunctional platform is a promissing candidate for improved activated drug release and phototherapy.