Organoselenium compounds as functionalizing agents for gold nanoparticles in cancer therapy

Gold nanoparticles (AuNPs) modified with four organoselenium compounds, i.e., 4-selenocyanatoaniline (com- pound 1), 4,4′-diselanediyldianiline (compound 2), N-(4-selenocyanatophenyl)cinnamamide (compound 3), and N-(3-selenocyanatopropyl)cinnamamide (compound 4), were synthesized following two different approaches: direct conjugation and non-covalent immobilization onto hydrophilic and non-cytotoxic AuNPs functionalized with 3-mercapto-1-propanesulfonate (3MPS). Both free compounds and AuNPs-based systems were characterized via UV-Vis, FTIR NMR, mass spectrometry, and SR-XPS to assess their optical and structural properties. Size and colloidal stability were evaluated by DLS and ζ-potential measurements, whereas morphology at solid-state was evaluated by atomic force (AFM) and scanning electron (FESEM) microscopies. AuNPs synthesized through chemical reduction method in presence of Se-based compounds as functionalizing agents allowed the formation of aggregated NPs with little to no solubility in aqueous media. To improve their hydrophilicity and stability mixed AuNPs-3MPS-1 were synthesized. Besides, Se-loaded AuNPs-3MPS revealed to be the most suitable sys- tems for biological studies in terms of size and colloidal stability. Selenium derivatives and AuNPs were tested in vitro via MTT assay against PC-3 (prostatic adenocarcinoma) and HCT-116 (colorectal carcinoma) cell lines. Compared to free compounds, direct functionalization onto AuNPs with formation of Au-Se covalent bond led to non-cytotoxic systems in the concentration range explored (0–100 μg/mL), whereas immobilization on AuNPs- 3MPS improved the cytotoxicity of compounds 1, 3, and 4. Selective anticancer response against HCT-116 cells was obtained by AuNPs-3MPS-1. These results demonstrated that AuNPs can be used as a platform to tune the in vitro biological activity of organoselenium compounds

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

Study of the interaction mechanism between hydrophilic thiol capped gold nanoparticles and melamine in aqueous medium

In the last years, intense efforts have been made in order to obtain colloidal-based systems capable of pointing out the presence of melamine in food samples. In this work, we reported about the recognition of melamine in aqueous solution, using gold nanoparticles stabilized with 3-mercapto-1-propanesulfonate (AuNPs-3MPS), with the aim of deepening how the recognition process works. AuNPs were synthesized using a wet chemical reduction method. The synthesized AuNPs-3MPS probe was fully characterized, before and after the recognition process, by both physicochemical (UV–vis, FT-IR, 1H-NMR, DLS and ζ-potential) and morphostructural techniques (AFM, HR-TEM). The chemical and electronic structure was also investigated by SR-XPS. The sensing method is based on the melamine-induced aggregation of AuNPs; the presence of melamine was successfully detected in the range of 2.5−500 ppm. The results achieved also demonstrate that negatively charged AuNPs-3MPS are potentially useful for determining melamine contents in aqueous solution. SR-XPS measurements allowed to understand interaction mechanism between the probe and the analyte. The presence of sulfonate groups allows a mutual interaction mediated by electrostatic bonds between nanoparticles surface thiols and positively charged amino groups of melamine molecules

In situ conjugation of silver nanoparticles with silane-functionalized TiO2 nanoparticles for antibacterial applications

TiO2 and Ag nanoparticles (NPs) are the two commonly employed inorganic materials in nanomedicine and in recent years, they have attracted growing interest in antibacterial applications. To enhance their biological efficacy, they can be used together in a single nanoplatform [1]. However, the TiO2-Ag conjugation is still challenging due to the aggregation issues, and it needs more studies to develop stable nanohybrids from these two components. One of the promising strategies is to employ biocompatible silane linkers to conjugate TiO2 with Ag nanoparticles to keep them stable in aqueous media. In this research, (3-mercaptopropyl)trimethoxysilane (3MPTMS) was applied as a bifunctional linker bearing soft –SH and hard –O parts in its structure to mediate the chemical conjugation of Ag to TiO2NPs. More importantly, this silane linker improves the biocompatibility of the resultant TiO2-Ag nanoconjugate. In brief, commercially available TiO2NPs with a size of 10-35 nm were firstly functionalized with 3MPTS (hydrolyzed form of 3MPTMS) with sol-gel method through the chemical attachment of titania with the –O moiety of the silane linker. Then Ag ions were coordinated to the free –SH groups on the TiO2-3MPTS surface followed by reduction to the AgNPs forming the final TiO2-3MPTS-Ag nanohybrid. For both Ag+ reduction and AgNPs stabilization, different reducing agents/stabilizers were investigated. The stability, size, morphology, and chemical composition of the nanohybrid were evaluated by UV-Vis, FT-IR, ATR, SEM-EDS, DLS, and XPS characterizations. Thanks to multidisciplinary collaborations, the in vitro antibacterial studies of TiO2-3MPTS-Ag are in progress

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

Silver nanoparticles as stimulating agents for arbuscular mycorrhizal fungi growth: a new perspective for agri-food

Silver nanoparticles (AgNPs) have recently been used in several fields, such as biomedicine, environmental treatment, food packaging and health care, due to their known antibacterial properties [1]. Nowadays, there is a widespread interest to use engineered nanomaterials in agriculture due to the possibility to obtain formulations for various agrochemicals, i.e., formulations of nanopesticides, nanofertilizers, nanosensors, and nanovectors [2,3]. The aim of the work is to enhance and increase the production of mycorrhized plants, a technique whereby fungi attach to the roots of a specific plant creating a symbiotic relationship, with Tuber melanosporum, also known as black truffle, through the controlled use of nanotechnology. This project belongs to TANA Regione Lazio activities. For this purpose, AgNPs with size of 50 nm were obtained through green synthesis approach using water as a solvent and following a bottom-up method. Two different ligands were used to prevent the aggregation of AgNPs during their growth: 3-mercapto-1-propansulfonate sodium salt (3MPS) and poly(acrylic acid) (PAA), to obtain negatively charged AgNPs-3MPS and AgNPs-PAA. Their size and stability in both aqueous and buffer media were evaluated by dynamic light scattering (DLS) and UV-vis for an interval of 0-30 days in the range of 5-50 ug mL-1. References [1] N. Baig, I. Kammakakam, W. Falath, I. Kammakakam, Mater. Adv., 2021, 2, 1821–1871. [2] C. An, C. Sun, N. Li, B. Huang, J. Jiang, Y. Shen, C. Wang, X. Zhao, B. Cui, C. Wang, X. Li, S. Zhan, F. Gao, Z. Zeng, H. Cui, Y. Wang, J. Nanobiotechnology, 2022, 20, 1–19. [3] I. Schiesaro, L. Burratti, C. Meneghini, I. Fratoddi, P. Prosposito, J. Lim, C. Scheu, I. Venditti, G. Iucci, C. Battocchio, J. Phys. Chem. C 2020, 124, 25975−25983

Silane-functionalized TiO2 nanoparticles decorated with Ag nanoparticles for dual antimicrobial effects

TiO2 and Ag nanoparticles (NPs) have attracted considerable attention in recent years due to the interesting antibacterial application of a single nanoplatform of these two components [1,2]. The direct TiO2-Ag conjugation is still challenging and opens applicative perspectives as a multifunctional nanotool for dual antimicrobial activity. In the present work, (3-mercaptopropyl)trimethoxysilane (3MPTMS) was selected as a bifunctional linker bearing –SH and –O moieties to mediate the chemical attachment of soft AgNPs to hard TiO2NPs. Moreover, the 3MPTMS linker can improve the stability and biocompatibility of TiO2-Ag nanoconjugate. Regarding the synthesis, commercially available TiO2NPs with a mean size of 50 nm were firstly functionalized with 3MPTS (hydrolyzed form of 3MPTMS) through the formation of Ti–O–Si bonds and then Ag ions were coordinated to the –SH groups of the TiO2NPs-3MPTS followed by reduction to the AgNPs forming the final TiO2-3MPTS-Ag nanohybrid. Different reducing agents were tested for both reduction of the coordinated-Ag+ and stabilization of the resultant AgNPs on the surface of TiO2NPs-3MPTS. The stability, size, morphology, and chemical composition of the nanoparticles were evaluated by extensive characterizations including FTIR-ATR, FESEM-EDS, and DLS. Thanks to multidisciplinary collaborations, the in vitro antibacterial property of this TiO2-Ag nanohybrid is in progress

Synthesis and characterizations of highly stable magnetite-silver (Fe3O4-Ag) nanohybrid for recyclable antibacterial materials

Due to their excellent antimicrobial activity, silver nanoparticles are considered as promising candidates against resistant pathogens. For such biological applications, it is of great importance to separate these nanoparticles from the surrounding media to prevent the potential contamination or aggregation. The Fe3O4 nanoparticles (Fe3O4NPs) are the mostly used magnetic materials in such fields, due to their biocompatibility, well-known chemistry/synthesis methods, and high surface area which allows to load many antibacterial agents on their surface [1]. In this research, highly stable silver nanoparticles, AgNPs-3MPS (3-MPS: 3- mercapto-1-propanesulfonate) were chemically decorated on the surface of silane-functionalized Fe3O4NPs. The (3-mercaptopropyl)trimethoxysilane (MPTS) was used for the silane functionalization to provide the free –SH groups on the Fe3O4NPs suitable for the chemical conjugation of AgNPs-3MPS with the magnetite surface. The Fe3O4NPs were synthesized by a coprecipitation of Fe(II) and Fe(III) ions in the presence of polyacrylic acid (PAA) as coating agent, followed by the surface silanization using a sol-gel method. Then AgNPs-3MPS were prepared in situ (reducing agent: NaBH4) and directly attached to the free –SH groups of Fe3O4NPs-PAA@MPTS forming the final nanohybrid. The stability, size, morphology, and chemical composition of both Fe3O4-PAA@MPTS and nanohybrid were evaluated by FT-IR/ATR, FESEM-EDS, DLS characterizations

Silver nanoparticles as efficient tool in agrifood applications

Silver nanoparticles (AgNPs) are widely used in several fields i.e., biomedicine, textile, cosmetic and healthcare [1]. Nowadays, there is a deep interest to use engineered nanomaterials in agrifood, as they can revolutionize agricultural systems using them in different ways [2]. This research aims to improve the production of mycorrhized plants with Tuber melanosporum (black truffle) through the controlled use of nanotechnology (Figure 1). Thus, hydrophilic AgNPs with a size range of 30-50 nm were synthesized via green synthesis approach, functionalized during their growth with 3-mercapto-1-propansulfonate sodium salt (3MPS) or poly(acrylic acid) (PAA). To study their different stabilizing efficiency through a covalently linked thiol or a polymeric matrix, DLS and UV-vis measurements. was assessed for an interval of 0-30 days and their functionalization was confirmed by FT-IR, NMR and SEM-EDX. This project belongs to the TANA Project funded by Regione Lazio. References [1] P. Fincheira, G. Tortella, A. B. Seabra, A. Quiroz, M. C. Diez, O. Rubilar, Planta, 2021, 254:66, 1–25. [2] I. Schiesaro, L. Burratti, C. Meneghini, I. Fratoddi, P. Prosposito, J. Lim, C. Scheu, I. Venditti, G. Iucci, C. Battocchio, J. Phys. Chem. C, 2020, 124, 25975−2598