Noble Metal Nanoparticles Networks Stabilized by Rod‐Like Organometallic Bifunctional Thiols

od-like organometallic dithiol containing square-planar Pt(II) centers, i. e., trans,trans- [(H3COCS)Pt(PBu3)2(C�C C6H4 C6H4 C�C)(PBu3)2Pt(SCOCH3)] was used as bifunctional stabilizing agent for the synthesis of Pd-, Au-, and AgNPs (MNPs). All the MNPs showed diameters of about 4 nm, which can be controlled by carefully modulating the synthesis parameters. Covalent MNPs stabilization occurred through a single S bridge between Pt(II) and the noble metal nanocluster surfaces, leading to a network of regularly spaced NPs with the formation of dyads, as supported by SR-XPS data and by TEM imaging analysis. The chemical nature of NPs systems was also confirmed by EDS and NMR. Comparison between SR-XPS data of MNPs and self-assembled monolayers and multilayers of pristine rod-like dithiols deposited onto polycrystalline gold surfaces revealed an electronic interaction between Pt(II) centers and biphenyl moieties of adjacent ligands, stabilizing the organic structure of the network. The possibility to obtain networks of regularly spaced MNPs opens outstanding perspectives in optoelectronics

Loading of phototherapeutic drug 5-aminolevulinic acid on TiO2 nanoparticles: a new approach for potential dual phototherapeutic effects

In cancer therapy, photodynamic technique (PDT) has attracted growing attention during the past decades. Among the drugs employed in PDT, 5-aminolevulinic acid (ALA) is one of their most effective ones due to its nontoxicity and quick excretion from the body. Despite the clinical significance of ALA, its application is sometimes restricted by its low chemical stability and its high hydrophilicity which result in the low penetration into cancer cells [1]. To improve the therapeutic efficacy of this drug, considerable efforts have been devoted to use inorganic-based nanodelivery systems [2]. To enhance the phototherapeutic efficacy of the nanoparticles-ALA conjugate (NPs-ALA), it is worth employing the photodynamic-active nanoparticles such as TiO2NPs. Low toxicity, chemical inertness, and biocompatibility of TiO2NPs make them suitable candidates for phototherapeutic studies. The aim of the project is to load ALA on the surface of polymer functionalized-TiO2NPs and their characterizations with UV-VIS, FT-IR, DLS and SEM techniques

Chemical conjugation of highly stable Ag nanoparticles with silane-functionalized TiO2 nanoparticles for potential dual antibacterial effect

Due to the different antibacterial mechanisms of Ag and TiO2 nanoparticles (NPs), and their unique physicochemical characteristics, combination of these two components in a single nanoplatform provides a multifunctional nanohybrid possessing synergistic effectiveness for a broader range of bacteria, especially for those which are resistant to common antibacterial drugs. For this reason, the TiO2-Ag nanohybrids have attracted a growing interest in recent years and there have been admirable efforts to develop their synthesis methods, structural properties, and applications [1]. Although there are acceptable conjugation methods, it still requires more studies to develop effective strategies to synthesize stable nanohybrids for the biological applications. One of the promising conjugation methods is to employ biocompatible siloxanes to mediate the conjugation of TiO2 with Ag nanoparticles keeping these nanocomponents stable in aqueous media. In this research, (3-mercaptopropyl)trimethoxysilane (3MPTMS) was used as a bifunctional linker bearing soft –SH and hard –O parts in its opposing sites of structure for the chemical conjugation of Ag to TiO2NPs. More importantly, this chemical coupling agent improves the biochemical properties of the resultant TiO2-Ag nanoconjugate. In brief, commercially available TiO2NPs with a size range of 10-35 nm were firstly modified with 3MPTS (hydrolyzed form of 3MPTMS) with a sol-gel method through the condensation of titania –OH groups with the –OH moiety of the silane linker. Then hydrophilic AgNPs-3MPS (3MPS: 3-mercapto1-propanesulfonate) were prepared in situ and directly attached to the free –SH groups of TiO2-3MPTS surface to form the final TiO2@3MPTS-Ag@3MPS nanohybrid. For the preparation of both TiO2@3MPTS and TiO2@3MPTS-Ag@3MPS, different reaction conditions were studied. The stability, size, morphology, and chemical composition of TiO2@3MPTS and the nanohybrid were evaluated by UV-Vis, FT-IR, SEM-EDS, DLS, 1H-NMR, and XPS characterizations. Thanks to multidisciplinary collaborations, the antibacterial studies of TiO2@3MPTS and TiO2@3MPTS-Ag@3MPS are in progress. [1] J. Z. Soo, L. Ching Chai, B. Chin Ang, B. Hoong Ong, ACS Appl. Nano Mater. 2020, 3, 5743