Eden E. L. Tanner

Electrochemical Detection of Ultratrace (Picomolar) Levels of Hg2+ Using a Silver Nanoparticle-Modified Glassy Carbon Electrode

Ultratrace levels of Hg2+ have been quantified by undertaking linear sweep voltammetry with a silver nanoparticle-modified glassy carbon electrode (AgNP-GCE) in aqueous solutions containing Hg2+. This is achieved by monitoring the change in the silver stripping peak with Hg2+ concentration resulting from the galvanic displacement of silver by mercury: Ag(np) + 1/2Hg2+(aq) → Ag+(aq) + 1/2Hg(l). This facile and reproducible detection method exhibits an excellent linear dynamic range of 100.0 pM to 10.0 nM Hg2+ concentration with R2 = 0.982. The limit of detection (LoD) based on 3σ is 28 pM Hg2+, while the lowest detectable level for quantification purposes is 100.0 pM. This method is appropriate for routine environmental monitoring and drinking water quality assessment since the guideline value set by the US Environmental Protection Agency (EPA) for inorganic mercury in drinking water is 0.002 mg L-1 (10 nM).

Ionic liquids for addressing unmet needs in healthcare

Abstract Advances in the field of ionic liquids have opened new applications beyond their traditional use as solvents into other fields especially healthcare. The broad chemical space, rich with structurally diverse ions, and coupled with the flexibility to form complementary ion pairs enables task‐specific optimization at the molecular level to design ionic liquids for envisioned functions. Consequently, ionic liquids now are tailored as innovative solutions to address many problems in medicine. To date, ionic liquids have been designed to promote dissolution of poorly soluble drugs and disrupt physiological barriers to transport drugs to targeted sites. Also, their antimicrobial activity has been demonstrated and could be exploited to prevent and treat infectious diseases. Metal‐containing ionic liquids have also been designed and offer unique features due to incorporation of metals. Here, we review application‐driven investigations of ionic liquids in medicine with respect to current status and future potential.

Transdermal insulin delivery using choline-based ionic liquids (CAGE)

ABSTRACT Transdermal delivery of pharmaceuticals using ionic liquids and deep eutectic solvents (DES) has attracted significant interest due to the inherent tunability of the molecules and their capacity to transport large molecules across the skin. Several key properties of DESs including viscosity, miscibility and possible transport enhancement can be controlled through the choice of ions and their ratio in DES. Herein we investigate the effect of cation/anion ratio using Choline and Geranic acid (CAGE) based DES. We synthesized variants of CAGE by controlling the ratio of Choline to Geranic acid over a range of 1:4 to 2:1. Physicochemical properties including viscosity, conductivity and diffusivity were measured. Effect of CAGE on skin permeability was assessed using insulin in ex vivo porcine skin. Each variant was found to have distinct properties, including interionic interactions, viscosity, and conductivity. In addition, the effect of CAGE on stratum corneum lipids, as assessed by FTIR, was dependent on its composition. Transport enhancement was also composition‐dependent, as the variants containing excess geranic acid (1:2 and 1:4, but not geranic acid alone) exhibited higher insulin delivery into the dermis compared to other compositions, demonstrating the importance of investigating the effect of ion ratios on drug delivery. Graphical abstract Figure. No caption available.

Nanoparticle Capping Agent Controlled Electron-Transfer Dynamics in Ionic Liquids.

Herein, we report a change in the mechanism of the oxidation of silver nanoparticles (Ag NPs) with the molecular weight of a poly(ethylene) glycol (PEG) capping agent. Characterisation of the modified nanoparticles is undertaken using dynamic light scattering and UV/Vis spectroscopy. Electrochemical analyses reveal that the oxidation of 6000 molecular weight (MW) PEG is consistent with a polymer-gated mechanism, whilst for 2000 MW PEG the polymer does not hinder the oxidation. The 10,000 MW PEG Ag NPs are rendered almost electrochemically inactive. This study demonstrates the ability to alter and better understand the electron-transfer mechanism in a room temperature ionic liquid (RTIL) by systematically altering the capping agent.

Quantifying the Polymeric Capping of Nanoparticles with X-Ray Photoelectron Spectroscopy

X-ray photoelectron spectroscopy was used to characterise silver nanoparticles capped with poly(ethylene) glycol (PEG) in a room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4 ]). The amounts of oxygen and silver present in nanoparticles capped with different molecular weight thiolated PEG chains were monitored, and the number of thiolated PEG chains per nanoparticle was calculated, an in situ characterisation not previously possible.