Fluorinated and Charged Hydrogenated Alkanethiolates Grafted on Gold: Expanding the Diversity of Mixed-Monolayer Nanoparticles for Biological Applications

Abstract

Low intrinsic toxicity, high solubility, and stability are important and necessary features of gold nanoparticles to be used in the biomedical field. In this context, charged nanoparticles proved to be very versatile, and among them charged mixed-monolayer gold nanoparticles, displaying monolayers with well-defined morphologies, represent a paradigm. By using mixtures of hydrogenated and fluorinated thiols, the formation of monolayer domains may be brought to an extreme because of the immiscibility of fluorinated and hydrogenated chains. Following this rationale, mixed monolayer gold nanoparticles featuring ammonium, sulfonate, or carboxylic groups on their surface were prepared by using amphiphilic hydrogenated thiols and 1H,1H,2H,2H-perfluoro-alkanethiols. The toxicity of these systems was assessed in HeLa cells and was found to be, in general, low even for the cationic nanoparticles which usually show a high cytotoxicity and is comparable to that of homoligand gold nanoparticles displaying amphiphiliccharge neutralhydrogenated or fluorinated thiolates in their monolayer. These properties make the mixed ligand monolayer gold nanoparticles an interesting new candidate for medical application.

Gold nanoparticles with patterned surface monolayers for nanomedicine: current perspectives

“…Along this line, Pasquato and coworkers combined approaches for preparing MPNPs by using mixtures of amphiphilic fluorinated and amphiphilic hydrogenated thiols bearing polyethylene glycol units of very different lengths (Bidoggia et al. 2017 ; Gentilini et al. 2009 ; Pengo and Pasquato 2015 ; Posocco et al.…”

Supramolecular Control of Azobenzene Switching on Nanoparticles

“…However, cofunctionalization of NPs with mixtures of polar and apolar ligands is not an easy task: earlier studies showed that such processes typically result in preferential adsorption of only one of the two ligands. Among numerous other examples, − Bishop and co-workers found that performing ligand exchange on DDA-capped 6 nm Au NPs with an 8:1 mixture of octadecanethiol and ω-mercaptoundecanoic acid resulted in a 0.35:1 mixture of these two ligands on the functionalized NPs, whereas Meli et al reported that a 3:1 molar ratio of dodecanethiol and ω-mercaptoundecanol used to functionalize 4 nm NPs was increased up to 32:1 as a result of the ligand exchange reaction . The discrepancy between the solution and the on-NP ratio typically originates from attractive/repulsive interactions between the ligands or when one of the ligands induces NP precipitation during the functionalization process.…”

Delivery of drugs, proteins, and nucleic acids using inorganic nanoparticles

“…The monolayer stabilizes the core and can be tailored with a range of functionalities to provide effective cellular uptake, controlled payload release, and cell-specific targeting [50]. Direct covalent attachment to the gold core can be used to deliver thiolated fluorophores [51] or small molecule drugs into the cell and into tumor tissue [52] with improved efficacy over free drug [53]. These coverings are stable outside cells but labile intracellularly due to much higher glutathione levels inside cells than extracellularly, providing a mechanism for internal release [54].…”