•A new method of preparing non-releasing antibacterial biomaterials was developed.•Antibacterial agent was synthesized into a deep eutectic solvent (DES).•DES was linked to the system through a covalent bond.•Hydrogen bonding in the DES is beneficial to limit antibacterial agent release.•The developed antibacterial dental composite has good biocompatibility.ObjectiveTo incorporate an antibacterial agent derived deep eutectic solvent (DES) into a dental resin composite, and investigate the resulting mechanical properties and antibacterial effects.MethodThe DES was derived from benzalkonium chloride (BC) and acrylic acid (AA) and was incorporated into the dental resin composite through rapid mixing. A three-point bending test was employed to measure the flexural strength of the composite. An agar diffusion test was used to investigate antibacterial activity. Artificial (accelerated) aging was undertaken by immersing the composites in buffer solutions at an elevated temperature for up to 4 weeks. UV–vis spectrophotometry and NMR analysis were conducted to study BC release from the composite. Finally, the biocompatibility of the composite materials was evaluated using osteoblast cell culture for 7 days. Results were compared to those of a control composite which contained no BC.ResultThe DES-incorporated composite (DES-C) displayed higher flexural strength than a similar BC-incorporated composite BC (BC-C) for the same level of BC. The inclusion of BC conferred antibacterial activity to both BC-containing composites, although BC-C produced larger inhibition halos than DES-C at the same loading of BC. Control composites which contained no BC showed negligible antibacterial activity. After artificial aging, the DES-C composite showed better maintenance of the mechanical properties of the control compared with BC-C, although a decrease was observed during the three-point bending test, particularly upon storage at elevated temperatures. No BC release was detected in the aged solutions of DES-C, whereas the BC-C showed a linear increase in BC release with storage time. Significantly, cell viability results indicated that DES-C has better biocompatibility than BC-C.SignificanceThe incorporation of a BC-based DES into a dental resin composite provides a new strategy to develop antibacterial dental materials with better biocompatibility and longer effective lifetimes without sacrificing the intrinsic mechanical properties of the composite structure.Download high-res image (106KB)Download full-size image

Sequestration of bovine serum albumin (BSA)-stabilized gold nanoclusters (AuNCs@BSA) prepared using microwave assistance within sol–gel-derived mesoporous silica films permits the selective and highly sensitive quenchometric detection of aqueous Hg2+ (limit of detection = 600 pM) with luminescence signal arising from oxidized BSA allowing for an analytically robust and reliable ratiometric detection. Overall, this work highlights a number of important advances, including the highest luminescence quantum yield reported to date for a protein-templated luminescent noble metal nanocluster (13%) made possible using a microwave-mediated synthesis followed by cold incubation. We also demonstrate the clear advantage of exploiting the luminescence signal arising from oxidized BSA as an internal reference to generate selectivity of response to Hg2+. A careful Stern–Volmer quenching analysis reveals the persistence of two unique quenching sites for AuNCs@BSA entrapped within a sol–gel-derived glass, a minor population of which is unquenchable. Finally, based on these AuNCs@BSA nanosensors, we advise a path forward for paper-based indicator strip detection of heavy metals in aqueous streams, the implementation of which can be performed using the unaided eye, making it a meaningful approach for routine screening and in resource-limited situations.

Task-specific ternary deep eutectic solvent (DES) systems comprising choline chloride, glycerol, and one of three different superbases were investigated for their ability to capture and release carbon dioxide on demand. The highest-performing systems were found to capture CO2 at a capacity of ∼10% by weight, equivalent to 2.3–2.4 mmol of CO2 captured per gram of DES sorbent. Of the superbases studied, 1,5-diazabicyclo[4.3.0]-non-5-ene (DBN) gave the best overall performance in terms of CO2 capture capacity, facility of release, and low sorbent cost. Interestingly, we found that only a fraction of the theoretical CO2 capture potential of the system was utilized, offering potential pathways forward for further design and optimization of superbase-derived DES systems for further improved reversible CO2 sequestration. Finally, the shear rate-dependent viscosities indicate non-Newtonian behavior which, when coupled to the competitive CO2 capture performance of these task-specific DESs despite a 1 to 2 orders of magnitude higher viscosity, suggest that the Stokes–Einstein–Debye relation may not be a valid predictor of performance for these structurally and dynamically complex fluids.Keywords: 1,5-Diazabicyclo[4.3.0]-non-5-ene (DBN); Carbon dioxide capture; CO2 sequestration; Deep eutectic solvent; DES;

In this work, we investigate the effects of modifiers on the carbon dioxide (CO2) capture/release abilities of silica-supported amine-based polymers. The primary amine-based polymers consisted of branched poly(ethylene amine) (PEI) and Jeffamine T-403, having aliphatic and ether-based backbones, respectively. These polymers were dispersed on nanosilica, and their CO2 capture/release abilities were determined with and without the addition of the Lewis basic polymer modifiers, poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA), and poly(ethylene glycol) (PEG). The greatest effect for increasing the CO2 capture capacity was observed for PEG additives while other modifiers lowered the capture capacity. However, PVAc and PMMA were found to significantly influence the kinetics of absorption and desorption. For absorption, modifiers improve mass transfer and offer better coverage of the silica surface so more amine groups are available at the surface of the sorbent for CO2 binding. Most markedly, while PEG improved desorption, PMMA and PVAc led to even faster desorption rates and higher regeneration abilities at 45 °C without the need for further heating. Thus, a combination of PEG and other Lewis base-containing modifiers have the potential to be used in concert to fine-tune the capacity, mass transfer, regeneration ability, and kinetics for amine-based CO2 sorbents.Keywords: Carbon capture; CO2 capture; Flue gas; Silica nanoparticles; Sorbents; Sustainability

In the present study, we have developed a novel dispersive liquid–liquid microextraction (DLLME) based on microwave-assisted DLLME (MADLLME) using ionic liquids for the separation of environmentally-relevant pyrethroid pesticides from various aqueous milieux. High-performance liquid chromatography (HPLC) was employed for the detection and quantitative tracking of the pesticides. Six different ILs were preliminarily tested as extraction solvents against four representative model pyrethroids. The optimization of the current method was derived by consideration of the dispersal solvent, ionic liquid choice, extraction container material, aqueous-phase pH, and microwave conditions (particularly, the applied power and irradiation time). Optimal results were achieved using methanol as a dispersal solvent with trioctylmethylammonium bis(trifluoromethylsulfonyl)imide ([N8881][Tf2N]) as the extraction solvent at a microwave power of 200 W for 60 s. A number of spiked food samples (e.g., honey, milk, assorted fruits) were also tested using MADLLME, with excellent recoveries achieved from these complex matrices as compared to DLLME alone.

Ionic liquids (ILs) sporting anions comprising the β-diketonate functionality were prepared, fully characterized via ESI-MS, FTIR, and 1H/13C NMR, and tested in multiple scenarios. We present eight new salts based on four different β-diketonate anions, each coupled with the choline or tetrabutylphosphonium cation. The thermal stabilities and transitions of these β-diketonate salts were explored using DSC and TGA. Seven of the compounds displayed melting points at or below 100 °C and hence formally qualify as ILs. The inherent binding capability of the β-diketonate moiety made possible a task-specific IL amenable to lanthanide recognition. For example, coordination with Eu3+ was accompanied by a striking three order-of-magnitude intensification of luminescence (‘turn-on’). Additionally, these ILs display prominent acidochromism. That is, the intense visible color of β-diketonate ILs is modulated in the presence of an acid source, permitting the visual transduction of local pH changes. Utility for carbon capture was also considered, however, these ILs were essentially incapable of binding CO2. Computational studies were better able to elucidate this behavior, revealing that the association of CO2 with the β-diketonate anion is thermodynamically unfavored and sterically hindered. Despite this negative result for CO2 capture, these newly introduced β-diketonate ILs show interesting and useful physicochemical properties applicable to a number of future applications.

Novel hybrid quasi-solid-state sorbents pairing inexpensive CO2-reactive polyethoxyamine (Jeffamine®) fluids with an abundantly available silica support have been investigated for carbon capture. The highest performance sorbent was capable of reversibly capturing close to 70 mg of CO2 per gram of sorbent at 45 °C, could be almost fully (∼90%) regenerated by simple vacuum swing, and was stable over many sequential capture–release cycles. The new supports can be handled as solventless, free-flowing powders even post-CO2 capture, obviating the mass flow problems arising from viscous liquid (or solid, gel, or wax) formation frequently attending carbamate formation. Our results have important ramifications for reducing the high costs of thermal regeneration in conventional carbon capture schemes, particularly in comparison with the aqueous monoethanolamine-based system currently favoured industrially. The strategy of uniformly dispersing a functional fluid onto a solid nanosupport in a manner that allows intimate contact with and diffusion of external gaseous species is additionally projected to find value in a range of gas separation and sensing endeavours.Graphical abstractHighlights► Jeffamine/silica sorbents are fabricated and shown to readily chemisorb CO2. ► Sorbents are easily regenerated by vacuum with no need for high temperatures. ► The discovery may lead to sorbents capable of carbon capture at low cost.

Ionic liquids display an array of useful and sometimes unconventional, solvent features and have attracted considerable interest in the field of green chemistry for the potential they hold to significantly reduce environmental emissions. Some of these points have a bearing on the chemical reactivity of these systems and have also generated interest in the physical and theoretical aspects of solvation in ionic liquids. This review presents an introduction to the field of ionic liquids, followed by discussion of investigations into the solvation properties of neat ionic liquids or mixed systems including ionic liquids as a major or minor component. The ionic liquid based multicomponent systems discussed are composed of other solvents, other ionic liquids, carbon dioxide, surfactants or surfactant solutions. Although we clearly focus on fluorescence spectroscopy as a tool to illuminate ionic liquid systems, the issues discussed herein are of general relevance to discussions of polarity and solvent effects in ionic liquids. Transient solvation measurements carried out by means of time-resolved fluorescence measurements are particularly powerful for their ability to parameterize the kinetics of the solvation process in ionic liquids and are discussed as well.

The fascinating and attractive features of ionic liquids (ILs) can be considerably expanded by mixing with suitable cosolvents, opening their versatility beyond the pure materials. We show here that mixtures of the IL 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 2,2,2-trifluoroethanol (TFE) display the intriguing phenomenon of hyperpolarity, examples of which are notably sparse in the literature. From the perspective of the ETN polarity scale and Kamlet–Taft parameters for hydrogen bond acidity (α) and basicity (β), the polarity of this mixture exceeds that of either neat component. Fluorescent molecular probes capable of engaging in hydrogen bonds (e.g., 2-(p-toluidino)naphthalene-6-sulfonate, TNS; 6-propionyl-2-(dimethylamino)naphthalene, PRODAN) also exhibit this curious behavior. The choice of IL anion appears to be essential as hyperpolarity is not observed for mixtures of TFE with ILs containing anions other than hexafluorophosphate. The complex solute–solvent and solvent–solvent interactions present in the [bmim][PF6] + TFE mixture were further elucidated using infrared absorbance, dynamic viscometry, and density measurements. These results are discussed in terms of Coulombic interactions, disruption of TFE multimers, formation of hyperanion preference aggregates, and “free” [bmim]+. It is our intent that these results open the door for computational exploration of related solvent mixtures while inspiring practical questions, such as whether such systems might offer the potential for stabilization of highly charged transition states or ionic clusters during (nano)synthesis.

The effect of addition of ionic liquids (ILs) on the aggregation behavior of a cyanine dye, 5,5′,6,6′-tetrachloro-1,1′-diethyl-3,3′-di(4-sulfobutyl)-benzimidazolocarbocyanine (TDBC), was investigated. In basic aqueous buffer solutions (pH ≥ 10), TDBC preferably exists in its J-aggregated form. Addition of hydrophilic ILs > 5 wt % is observed to disrupt the TDBC J-aggregates, converting them to monomer form most likely because of the interaction between bulky IL cation and the J-aggregates in a time-dependent fashion. This is evidenced by the observed increase in monomer band absorbance at the expense of the absorbance band due to J-aggregates over time. Inorganic salts at similar molar concentrations do not cause this phenomenon but instead induce TDBC precipitation. At low concentrations (<5 wt %), the added IL acts similarly to the inorganic salts, reducing the overall absorbance of TDBC in the solution most likely due to cation exchange causing TDBC precipitation. Addition of a molecular solvent, ethanol, at 15 wt % results in an initial increase in monomer absorbance, albeit to a much lesser extent than for the corresponding molar fraction of IL, which then decreases over time with recovery of J-aggregate absorbance—quite opposite the time-dependent behavior seen for TDBC in PB at pH 12.0 with >5 wt % IL. The unique and dual behavior of ILs as an additive toward affecting cyanine dye aggregation is demonstrated.