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

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

Functionalized gold nanorods as drug carriers: a promising antiviral system

Functionalized gold nanorods (AuNRs) are innovative tools useful in theranostics, combining diagnostics and therapy and allowing optimal and personal treatment of patients. Moreover, AuNRs are studied for use in photothermal therapy and imaging thanks to the peculiar phenomenon of Localised Surface Plasmon Resonance (LSPR), which allows them to be identified through spectroscopic techniques in the energy range in which biological tissues are not active. Their functionalization can involve a variety of molecules, including specific drugs or peptides, allowing a controlled transport and release of desired drugs. In this framework, AuNRs were synthesised and characterised through spectroscopic (UV–Vis-NIR, XPS) and microscopic techniques (TEM, FE-SEM). Furthermore, their cytotoxic activity was evaluated on Vero E6 cell line by MTT assay. The data obtained confirm the AuNRs are promising carriers for antiviral drugs, opening new possibilities of application for biomedical field

takos: An R Package For Thermal Analysis Calculations

publishedVersio

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

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

A Simple Cerium Coating Strategy for Titanium Oxide Nano-tubes’ Bioactivity Enhancement

Despite the well-known favorable chemical and mechanical properties of titanium-based materials for orthopedic and dental applications, poor osseointegration of the implants, bacteria adhesion, and excessive inflammatory response from the host remain major problems to be solved. Here, the antioxidant and anti-inflammatory enzyme-like abilities of ceria (CeOx) were coupled to the advantageous features of titanium nanotubes (TiNTs). Cost-effective and fast methods, such as electrochemical anodization and drop casting, were used to build active surfaces with enhanced bioactivity. Surface composition, electrochemical response, and in vitro ability to induce hydroxyapatite (HA) precipitation were evaluated. The amount of cerium in the coating did not significantly affect wettability, yet a growing ability to induce early HA precipitation from simulated body fluid (SBF) was observed as the oxide content at the surface increased. The presence of 4%wt CeOx was also able to stimulate rapid HA maturation in a (poorly) crystalline form, indicating an interesting potential to induce rapid in vivo osseointegration process

Direct Conjugation of TiO2 Nanoparticles with Phototherapeutic Prodrug 5‐Aminolevulinic Acid

TiO2 nanoparticles (TiO(2)NPs) were directly conjugated with the phototherapeutic prodrug, 5-aminolevulinic acid (ALA), using a mild and green approach. The resultant TiO(2)NPs-ALA nanoconjugates were characterized by different techniques, including HPLC, UV-Vis, FTIR-ATR, H-1-NMR, FESEM-EDS, TEM, DLS, and synchrotron radiation-induced XPS (SR-XPS) to assess the successful loading of 15 % and the chemical stability of ALA on the TiO(2)NPs. More importantly, the SR-XPS results showed the stabilizing effect of TiO2 nanosurface on the ALA molecules (against structural change) in neutral and alkaline pHs, which is of great significance in the potential therapeutic applications of ALA. The FESEM and TEM results exhibited the grain-like TiO(2)NPs-ALA particles with a 20-50 nm size distribution, indicating size-controlling effect of ALA on the TiO(2)NPs during the conjugation process and the presence of the organic molecule layer onto the surface. TiO(2)NPs-ALA represents a promising candidate for studies in photodynamic therapy considering the stabilization effect observed by spectroscopic characterizations

A Simple Cerium Coating Strategy for Titanium Oxide Nanotubes’ Bioactivity Enhancement

Despite the well-known favorable chemical and mechanical properties of titanium-based materials for orthopedic and dental applications, poor osseointegration of the implants, bacteria adhesion, and excessive inflammatory response from the host remain major problems to be solved. Here, the antioxidant and anti-inflammatory enzyme-like abilities of ceria (CeOx) were coupled to the advantageous features of titanium nanotubes (TiNTs). Cost-effective and fast methods, such as electrochemical anodization and drop casting, were used to build active surfaces with enhanced bioactivity. Surface composition, electrochemical response, and in vitro ability to induce hydroxyapatite (HA) precipitation were evaluated. The amount of cerium in the coating did not significantly affect wettability, yet a growing ability to induce early HA precipitation from simulated body fluid (SBF) was observed as the oxide content at the surface increased. The presence of 4%wt CeOx was also able to stimulate rapid HA maturation in a (poorly) crystalline form, indicating an interesting potential to induce rapid in vivo osseointegration process

Silane-functionalized metal oxide nanoparticles link silver nanoparticles: a new platform for antibacterial applications

Due to the different antibacterial mechanisms of Ag nanoparticles (AgNPs) and metal oxide nanoparticles (MONPs), and their unique physicochemical characteristics, combination of these 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 MO-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 [1,2]. One of the promising conjugation methods is to employ biocompatible siloxanes to mediate the conjugation of MO 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 MO NPs. More importantly, this chemical coupling agent improves the biochemical properties of the resultant MO-Ag nanoconjugate