Obtention of Metallic Nanowires by Protein Biotemplating and Their Catalytic Application

Gold nanowires were obtained by a seeded growth process using protein lysozyme fibrils as biotemplates. The degree of metal coverage until full biotemplate coverage onto the fibril was controlled by the gold salt concentration and the number of sequential additions of metal growth solutions. The hybrid fibrils might have a potential use as catalysts since they display enhanced catalytic activity in the reduction of <i>p-</i>nitrophenol to <i>p-</i>aminophenol by NaBH₄

Fluorescent Drug-Loaded, Polymeric-Based, Branched Gold Nanoshells for Localized Multimodal Therapy and Imaging of Tumoral Cells

Here we report the synthesis of PLGA/DOXO-core Au-branched shell nanostructures (BGNSHs) functionalized with a human serum albumin/indocyanine green/folic acid complex (HSA-ICG-FA) to configure a multifunctional nanotheranostic platform. First, branched gold nanoshells (BGNSHs) were obtained through a seeded-growth surfactant-less method. These BGNSHs were loaded during the synthetic process with the chemotherapeutic drug doxorubicin, a DNA intercalating agent and topoisomerase II inhibitior. In parallel, the fluorescent near-infrared (NIR) dye indocyanine green (ICG) was conjugated to the protein human serum albumin (HSA) by electrostatic and hydrophobic interactions. Subsequently, folic acid was covalently attached to the HSA-ICG complex. In this way, we created a protein complex with targeting specificity and fluorescent imaging capability. The resulting HSA-ICG-FA complex was adsorbed to the gold nanostructures surface (BGNSH-HSA-ICG-FA) in a straightforward incubation process thanks to the high affinity of HSA to gold surface. In this manner, BGNSH-HSA-ICG-FA platforms were featured with multifunctional abilities: the possibility of fluorescence imaging for diagnosis and therapy monitoring by exploiting the inherent fluorescence of the dye, and a multimodal therapy approach consisting of the simultaneous combination of chemotherapy, provided by the loaded drug, and the potential cytotoxic effect of photodynamic and photothermal therapies provided by the dye and the gold nanolayer of the hybrid structure, respectively, upon NIR light irradiation of suitable wavelength. The combination of this trimodal approach was observed to exert a synergistic effect on the cytotoxicity of tumoral cells <i>in vitro</i>. Furthermore, FA was proved to enhance the internalization of nanoplatform. The ability of the nanoplatforms as fluorescence imaging contrast agents was tested by preliminary analyzing their biodistribution <i>in vivo</i> in a tumor-bearing mice model

Targeted Combinatorial Therapy Using Gold Nanostars as Theranostic Platforms

This paper reports the development of a multimodal therapy nanoplatform based on gold nanostars (Au NS) as core particles. These NS were functionalized with the chemotherapeutic drug doxorubicin (DOXO), which was conjugated to the NS surface by means of a cleavable heterobifunctional cross-linker (sulfo-LC-SPDP) to allow its release under the action of reducing enzymes. To ensure a specific delivery of the chemotherapeutic drug, the nanoplatform was additionally functionalized with folic acid (FA) as targeting ligand and cellular uptake adjuvant. By synthetically modifying the plasmon band of Au NS to the near-infrared (NIR) region of the electromagnetic spectrum, the present nanoplatform was able to simultaneously combine the capability of photothermal therapy (PTT) through the conversion of absorbed light energy into localized heat and chemotherapy, enabling their monitoring by means of optical fluorescence imaging thanks to DOXO’s autofluorescence. Cellular uptake was observed to be enhanced when the Au NPs were decorated with the targeting ligand. In addition, the therapeutic efficiency of the nanoplatform tested in HeLa cells demonstrated the larger cytotoxicity efficiency of the combined therapy if compared to individual ones