Direct binding and characterization of laccase onto iron oxide nanoparticles.

Iron oxide nanoparticles (IONPs) exhibit unique magnetic properties and possess a high surface-to-volume ratio, making them ideal candidates for the conjugation of substances, including enzymes. Laccase (EC 1.10.3.2), an oxidative enzyme with diverse applications, presents an opportunity for enhancing stability and reusability through innovative immobilization techniques, thus reducing overall process costs. In this study, we employed a direct binding procedure via carbodiimide activation to conjugate laccase onto IONPs synthesized using thermal chemical coprecipitation. Stabilization of the nanoparticles was achieved using thioglycerol and polyvinyl alcohol (PVA) as capping agents. Characterization of the synthesized nanoparticles was conducted using UV-spectroscopy, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction, scanning electron microscopy, and energy dispersive x-ray spectroscopy. FTIR spectroscopy analysis confirmed successful laccase binding to magnetic nanoparticles, with binding efficiencies of 90.65% and 73.02% observed for thioglycerol and PVA capped IONPs, respectively. Furthermore, the conjugated enzyme exhibited remarkable stability, retaining nearly 50% of its initial activity after 20 reuse cycles. This research demonstrates that immobilizing laccase onto IONPs enhances its activity, stability, and reusability, with the potential for significant cost savings and expanded applications in various fields.

Biocompatibility and antimicrobial effect of demineralised dentin matrix hydrogel for dental pulp preservation.

Regeneration of dentin and preserving pulp vitality are essential targets for vital pulp therapy. Our study aimed to evaluate a novel biomimetic pulp capping agent with increased dentin regenerative activities. To produce demineralised dentin matrix (DDM) particles, human extracted teeth were ground and treated with ethylene diamine tetra-acetic acid solution. DDM particles were added to sodium alginate and this combination was dripped into a 5% calcium chloride to obtain DDM hydrogel (DDMH). The eluants of both DDMH and mineral trioxide aggregate (MTA) were tested using an MTT assay to detect their cytotoxic effect on dental pulp stem cells (DPSC). Collagen-I (COL-I) gene expression was analysed on DPSC exposed to different dilutions of pulp capping material eluants by real-time quantitative polymerase chain reaction. Acridine orange staining was used to monitor the cell growth over the tested materials. Agar diffusion assay was utilised to test the antibacterial effect of DDMH and MTA compared to controls. MTT assay revealed that neat eluates of DDMH promoted DPSC viability. However, neat eluates of MTA were cytotoxic on DPSC after 72 h of culture. Moreover, DPSC were capable of growth and attached to the surface of DDMH, while they showed a marked reduction in their number when cultured on the MTA surface for one week, as shown by the acridine orange stain. In DPSC cultured with DDMH eluates, the COL-I gene was overexpressed compared to those cultured with MTA eluants. DDMH had significant antimicrobial activity in comparison to MTA after 24 h incubation. This in vitro study showed that DDMH could be an alternative pulp capping agent for regenerative endodontics.

Selenium Nanoparticles: Green Synthesis and Biomedical Application.

Selenium nanoparticles (SeNPs) are extremely popular objects in nanotechnology. "Green" synthesis has special advantages due to the growing necessity for environmentally friendly, non-toxic, and low-cost methods. This review considers the biosynthesis mechanism of bacteria, fungi, algae, and plants, including the role of various biological substances in the processes of reducing selenium compounds to SeNPs and their further packaging. Modern information and approaches to the possible biomedical use of selenium nanoparticles are presented: antimicrobial, antiviral, anticancer, antioxidant, anti-inflammatory, and other properties, as well as the mechanisms of these processes, that have important potential therapeutic value.

Hornification: Lessons learned from the wood industry for attenuating this phenomenon in plant-based dietary fibers from food wastes.

A significant amount of waste is annually generated worldwide by the supply chain of the food industry. Considering the population growth, the environmental concerns, and the economic opportunities, waste recovery is a promising solution to produce valuable and innovative ingredients for food and nonfood industries. Indeed, plant-based wastes are rich in dietary fibers (DF), which have relevant technical functionalities such as water/oil holding capacity, swelling capacity, viscosity, texture, and physiological properties such as antioxidant activity, cholesterol, and glucose adsorption capacities. Different drying technologies could be applied to extend the shelf life of fresh DF. However, inappropriate drying technologies or process conditions could adversely affect the functionalities of DF via the hornification phenomenon. Hornification is related to the formation of irreversible hydrogen bindings, van der Waals interactions, and covalent lactone bridges between cellulose fibrils during drying. This review aims to capitalize on the knowledge developed in the wood industry to tackle the hornification phenomenon occurring in the food industry. The mechanisms and the parameters affecting hornification as well as the mitigation strategies used in the wood industry that could be successfully applied to foods are summarized. The application of conventional drying technologies such as air or spray-drying increased the occurrence of hornification. In contrast, solvent exchange, supercritical drying, freeze-drying, and spray-freeze-drying approaches were considered effective strategies to limit the consequences of this phenomenon. In addition, incorporating capping agents before drying attenuated the hornification. The knowledge summarized in this review can be used as a basis for process design in the valorization of plant-based wastes and the production of functional DF that present relevant features for the food and packaging industries.

Incorporation of Green Capping Agents to Reduce Silver-Mediated Dentine Staining.

Silver diammine fluoride (SDF) is known as a noninvasive, cost-effective, safe, and simple method of dental caries treatment. However, staining and discoloration seem inseparable with SDF and continue as a cosmetic concern. Research is ongoing to overcome these issues, for example, by using glutathione (G) or potassium iodide among others. Therefore, the study aimed to investigate the effects of incorporating different concentrations of capping agents on SDF chemistry and SDF-mediated tooth staining at different time points. Tannic acid (TA), gallic acid (GA), carboxymethyl chitosan (CM), and G at different concentrations (5, 10, and 15% w/v) were incorporated in 30% SDF. FTIR and UV-Vis spectroscopies of the prepared solutions was performed to evaluate chemical changes. Time-dependent color changes (ΔE) in bovine dentine specimens (6 × 6 × 1 ± 0.25 mm3) were measured spectrophotometrically at application/washup, 1 and 3 h, after 1, 2, 4, 7, and 14 days. Results showed suppression of FTIR peaks at 3,358 cm-1 and 1,215 cm-1 in capping agent-modified SDF indicative of a successful capping effect of the silver ions, which was corroborated by UV-Vis blueshift of ∼∆32 nm. The capping effect on SDF increased proportionally with the concentrations of TA, GA, CM, and G used. A more pronounced tooth staining reduction however was shown more in TA- and G- rather than in GA- and CM-modified SDF. At day 14, SDF showed the highest mean ΔE(50.14 ± 2.14), while 15% TA showed the lowest ΔE(30.14 ± 0.81). In conclusion, capping agent incorporation significantly reduced SDF-mediated tooth staining. This reduction in staining is more dependent on the respective capping agent functional groups than concentrations per se. The potential of capping agents to minimize tooth staining of SDF was TA>G>CM>GA.

Significance of Capping Agents of Colloidal Nanoparticles from the Perspective of Drug and Gene Delivery, Bioimaging, and Biosensing: An Insight.

The over-growth and coagulation of nanoparticles is prevented using capping agents by the production of stearic effect that plays a pivotal role in stabilizing the interface. This strategy of coating the nanoparticles' surface with capping agents is an emerging trend in assembling multipurpose nanoparticles that is beneficial for improving their physicochemical and biological behavior. The enhancement of reactivity and negligible toxicity is the outcome. In this review article, an attempt has been made to introduce the significance of different capping agents in the preparation of nanoparticles. Most importantly, we have highlighted the recent progress, existing roadblocks, and upcoming opportunities of using surface modified nanoparticles in nanomedicine from the drug and gene delivery, bioimaging, and biosensing perspectives.

Is Bioactive Glass an Effective Agent in Pulp-capping Treatments?: A Randomized Controlled Clinical Trial with One-year Follow-up.

AIMS: Indirect pulp-capping treatment is a procedure applied to teeth with deep and close-to-pulp caries lesions and without pulp degeneration symptoms. This study aimed to explore the use of a material containing bioactive glass for indirect pulp capping in primary and permanent teeth. MATERIALS AND METHODS: The study included 145 patients, aged 4-15 years, without any systemic disease and 100 primary second molars and 100 permanent first molars in total. Four material groups were determined: calcium hydroxide (Dycal-DC group), glass ionomer (Biner LC-BC group), calcium silicate (TheraCal LC-TC group), and Bioactive glass-containing ACTIVA BioACTIVE-AC group. Clinical and radiographic evaluations were made 1, 3, 6, 9, and 12 months after the treatment. The data obtained were statistically analyzed using the Chi-square test. RESULTS: During the 12-month follow-up period, the DC and TC groups were more successful clinically (94%), while the DC and AC groups were found to be more successful radiographically (94%). However, no statistically significant difference was found between the groups (p > 0.05). CONCLUSIONS: The results of this study supported the view that the success of indirect pulp-capping treatments was independent of the material used. CLINICAL SIGNIFICANCE: This study demonstrated that a material containing bioactive glass, ACTIVA BioACTIVE-Base/Liner, can be used safely in indirect pulp-capping processes.

The management of deep caries in UK primary care: A nationwide questionnaire-based study.

AIM: To investigate current approaches and attitudes towards the management of deep caries in primary dental care within the United Kingdom (UK). METHODOLOGY: Open distribution of an electronic questionnaire survey was undertaken to primary care dental professionals working in publicly funded National Health Service [NHS], privately funded, military and community dental services. Demographic variables investigated included the following: place of qualification, method of remuneration, level of restorative training, materials available, years qualified, appointment length and clinician type. Management variables focussed on case-based scenarios. Univariate analyses of responses to questions were undertaken using χ2 tests with sequential Bonferroni correction. Variables with a statistical relationship of p ≤ .2 were selected for binary logistic regression modelling. RESULTS: A total of 657 responses were received. Practitioners with formal postgraduate qualifications (PGQ) were more likely (OR, 95%CI) to undertake further tests to aid diagnosis including: gaining a patient history (1.80, 1.01-3.20), periapical radiography (1.43, 1.01-2.03), cold pulp testing (2.079, 1.46-2.97) and electric pulp testing (1.65, 1.02-2.65). Rubber dam was infrequently used for deep caries management (29.2%). Non-NHS practitioners were much more likely to use rubber dam (3.40, 2.15-5.37), as were those that had completed PGQ (2.24, 1.48-3.38). Non-selective caries removal was used in deep caries by 41.4% of practitioners. Indirect pulp caps were carried out by 56.7% of practitioners. NHS practitioners were more likely to place calcium hydroxide (3.74, 1.97-7.15), whilst non-NHS practitioners were more likely to place calcium silicate cements (CSCs) (3.303, 1.71-6.38) as were non-UK graduates (5.63, 2.47-12.86) and those with PGQ (2.12, 1.17-3.87). CONCLUSIONS: This UK survey highlights significant variation in the management of deep caries. There is lack of consensus regarding the use of a standard systematic approach to diagnosing disease, with a reliance on history and tests with poor specificity. Non-selective caries removal for managing deep carious lesions remains common, with low rubber dam compliance underlining a lack of asepsis. Notably, a significant number of practitioners placed indirect pulp caps, but CSCs and GIC were not commonly used. At present, although clear guidelines are available this is not translating into consistent management approaches in practice, suggesting that better dissemination of current treatments is essential to undergraduate and postgraduate groups.

How is carious pulp exposure and symptomatic irreversible pulpitis managed in UK primary dental care?

AIM: To investigate attitudes and approaches of UK primary care dentists to carrying out vital pulp treatment (VPT) after carious exposure and with additional signs and symptoms indicative of irreversible pulpitis. METHODOLOGY: An electronic questionnaire was openly distributed via publicly funded (NHS) local dental committees, corporate dental service-providers, professional societies and social media. Principally NHS practitioners and those from mixed and private practice were targeted, in addition to community and military dental officers, and dental therapists. Participants were asked questions relating to several clinical scenarios, with responses analysed using descriptive statistics. χ2 tests with sequential Bonferroni correction were used to explore variables including the method of remuneration, practitioner type (dentist/therapist), postgraduate qualification(s), place of graduation and years since qualification. Variables with a relationship p ≤ .2 were selected for backwards likelihood ratio logistic modelling. RESULTS: In total, 648 primary care practitioners were included for analysis. Calcium hydroxide (CH) was most frequently used for direct pulp caps (DPCs) (398/600; 66.3%) with calcium silicate cements (CSCs) less frequently used (119/600; 19.8%). Rubber dam was used by 222/599 (37.1%) practitioners. A definitive pulpotomy for the management of teeth with signs and symptoms indicative of irreversible pulpitis was selected by 65/613 (10.6%) dentists. The principal barrier for the provision of definitive pulpotomies was a lack of training (602/612; 98.4%). Regression analysis identified NHS practitioners as a good predictor for using CH for DPCs, having shorter emergency appointments, limited access to magnification and not using rubber dam. Non-UK graduates were more likely to select CSCs, appropriately control pulpal haemorrhage, undertake appropriate postoperative evaluation and use rubber dam. CONCLUSIONS: Practitioners deviated from evidence-based guidelines in a number of aspects including material selection, asepsis and case selection. A number of other challenges exist in primary care in providing predictable VPTs, including lack of time and access to magnification. These were most evident in NHS practice, potentially exacerbating existing social health inequalities. Possible inconsistencies in the UK undergraduate curriculum were supported by a lack of association between years since qualification and technique employed as well as the fact that non-UK graduates and dentists with postgraduate qualifications adhered more to evidence-based VPT guidelines.

Controlled Synthesis of Polyphosphazenes with Chain-Capping Agents.

N-alkyl phosphoranimines were synthesized via the Staudinger reaction of four different alkyl azides with tris(2,2,2-trifluoroethyl) phosphite. N-adamantyl, N-benzyl, N-t-butyl, and N-trityl phosphoranimines were thoroughly characterized and evaluated as chain-capping compounds in the anionic polymerization of P-tris(2,2,2-trifluoroethoxy)-N-trimethylsilyl phosphoranimine monomer. All four compounds reacted with the active chain ends in a bulk polymerization, and the alkyl end groups were identified by 1H-NMR spectroscopy. These compounds effectively controlled the molecular weight of the resulting polyphosphazenes. The chain transfer constants for the monomer and N-benzyl phosphoranimine were determined using Mayo equation.

Separating Growth from Nucleation for Facile Control over the Size and Shape of Palladium Nanocrystals.

In order to maximize the performance of nanocrystals in a specific application, it is necessary to control both their size and shape. Here we report a one-pot protocol that allows us to separate growth from nucleation for achieving better control over the size and shape of Pd nanocrystals. The two processes are temporally separated from each other, although the synthesis is carried out in the same reaction container. Size control is achieved by simply varying the ratio between the amounts of precursor allocated to the growth and nucleation processes. With the involvement of seeds at a fixed number, increasing the amount of precursor for growth leads to increasingly larger nanocrystals. Shape control is made possible by varying the capping agent, with bromide leading to a cubic shape and citrate inducing the formation of an octahedral shape. The synthesis can also be scaled up by at least tenfold without compromising the quality.

Role of capping agents in the application of nanoparticles in biomedicine and environmental remediation: recent trends and future prospects.

Capping agents are of utmost importance as stabilizers that inhibit the over-growth of nanoparticles and prevent their aggregation/coagulation in colloidal synthesis. The capping ligands stabilize the interface where nanoparticles interact with their medium of preparation. Specific structural features of nanoparticles are attributed to capping on their surface. These stabilizing agents play a key role in altering the biological activities and environmental perspective. Stearic effects of capping agents adsorbed on the surface of nanoparticles are responsible for such changing physico-chemical and biological characteristics. Firstly, this novel review article introduces few frequently used capping agents in the fabrication of nanoparticles. Next, recent advancements in biomedicine and environmental remediation approaches of capped nanoparticles have been elaborated. Lastly, future directions of the huge impact of capping agents on the biological environment have been summarized.

Chromatographic identification of "green capping agents" extracted from Nasturtium officinale (Brassicaceae) leaves for the synthesis of MoO3 nanoparticles.

A low-temperature, efficient and effective method was investigated for phytochemical hydroethanolic extraction of Nasturtium officinale (Brassicaceae). The phytocompounds of the selected plant leaves were identified by high-performance liquid chromatography, gas chromatography with mass spectroscopy, Fourier transform infrared spectroscopy, and ultraviolet-visible spectroscopy. Acetic acid, d-alanine, octodrine, decanoic acid, and cyclohexylethylamine were the major phytocompounds identified in N. officinale leaves with high similarity match and spectral purity. The reducing and stabilizing potential of the extracted phytochemicals was demonstrated by synthesizing the metal oxide nanoparticles (MoO3 ) by treating ammonium heptamolybdate tetrahydrate (H4 MO7 N6 O24 .4H2 O) aqueous complex with bioactive compounds of the leaves. The bio-synthesized MoO3 nanoparticles were characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, field emission-scanning electron microscopy, and gas chromatography with mass spectroscopy. Gas chromatography-mass spectroscopy identified acetic acid, d-alanine, and octodrine as stabilizing agents in the synthesis of MoO3 nanoparticles.

Surface Capping Agents and Their Roles in Shape-Controlled Synthesis of Colloidal Metal Nanocrystals.

Surface capping agents have been extensively used to control the evolution of seeds into nanocrystals with diverse but well-controlled shapes. Here we offer a comprehensive review of these agents, with a focus on the mechanistic understanding of their roles in guiding the shape evolution of metal nanocrystals. We begin with a brief introduction to the early history of capping agents in electroplating and bulk crystal growth, followed by discussion of how they affect the thermodynamics and kinetics involved in a synthesis of metal nanocrystals. We then present representative examples to highlight the various capping agents, including their binding selectivity, molecular-level interaction with a metal surface, and impacts on the growth of metal nanocrystals. We also showcase progress in leveraging capping agents to generate nanocrystals with complex structures and/or enhance their catalytic properties. Finally, we discuss various strategies for the exchange or removal of capping agents, together with perspectives on future directions.

A Quantitative Analysis of the Reduction Kinetics Involved in the Synthesis of Au@Pd Concave Nanocubes.

Surface capping has been shown to play a pivotal role in controlling the evolution of metal nanocrystals into different shapes or morphologies. With the synthesis of Au@Pd concave nanocubes as an example, here we demonstrate that the capping agent can also impact the reduction kinetics of a precursor, and thereby its reduction pathway, for the formation of metal nanocrystals with distinct morphologies. A typical synthesis involves the reduction of a PdII precursor by ascorbic acid at room temperature in the presence of Au nanospheres as seeds, together with the use of hexadecyltrimethylammonium chloride (CTAC) or hexadecyltrimethylammonium bromide (CTAB) as the capping agent. In the case of CTAC, the PdII precursor prevails as PdCl4 2- , leading to the formation of Au@Pd concave nanocubes with a rough surface because of the fast reduction kinetics and thus the dominance of solution reduction pathway. When switched to CTAB, the PdII precursor changes to PdBr4 2- that features slow reduction kinetics and surface reduction pathway. Accordingly, the Au@Pd concave nanocubes take a smooth surface. This work demonstrates that both reduction kinetics and surface capping play important roles in controlling the morphology of metal nanocrystals and these two roles are often coupled to each other.

Preparation of Highly Biocompatible ZnSe Quantum Dots Using a New Source of Acetyl Cysteine as Capping Agent.

In this paper, we describe a facile method for preparation of ZnSe quantum dots (QDs) using an inexpensive and biocompatible source of acetyl cysteine in aqueous media. The structural properties of the ZnSe QDs have been characterized using XRD, FT-IR, and TEM techniques. The optical properties of the as-prepared QDs were found to be size-dependent, due to the strong confinement regime at relatively low refluxing time. Effect of solution pH and refluxing temperature on absorption and emission characteristics of the ZnSe QDs was studied. The empirical effective mass approximation also reveals that, both solution pH and refluxing temperature parameters would effect on ZnSe QDs growth, and increase their size. However, the influence of the solution pH was found to be more prominent. Water-solubility, high emission intensity and sub-10 nm nanocrystals size are the most essential features that suggest our synthesized aqueous-based ZnSe QDs (with a very cost-effective and biocompatible capping agent) can be utilized for biological intentions.

Analysis of organic components in resin-modified pulp capping materials: critical considerations.

The purpose of this study was to elucidate the organic composition and eluates of three resin-based pulp-capping materials in relation to their indications and safety data sheets. Uncured samples of Theracal LC, Ultra-Blend Plus, and Calcimol LC were investigated using gas chromatography-mass spectrometry (GC-MS) and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Identification/quantification of 7-d leachables of cured samples was performed using GC-MS for 2-hydroxyethyl methacrylate (HEMA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), camphorquinone (CQ), ethylene glycol dimethacrylate (EGDMA), ethyl-4-(dimethylamino)benzoate (DMABEE), and triethylene glycol dimethacrylate (TEGDMA). A similar organic composition was found for Ultra-Blend and Calcimol; however, only Ultra-Blend is indicated for direct pulp-capping. In contrast to the other materials analysed, Theracal contained substances of high molecular weight. The safety data sheets of all materials were incomplete. We detected HEMA, CQ, and TEGDMA in eluates from Ultra-Blend and Calcimol, and it was considered that HEMA might have originated from decomposition of diurethane dimethacrylate (UDMA) in the GC-injector. For Theracal, additives associated with light curing (DMABEE and CQ) were detected in higher amounts (4.11 and 19.95 µg mm-2 ) than in the other materials. Pores were quantified in all samples by micro-computed tomography (micro-CT) analysis, which could influence leaching. The organic substances in the investigated materials might affect their clinical suitability as capping agents, especially for direct capping procedures.

Synthesis of ZnO nanoparticles using a hydrothermal method and a study its optical activity.

ZnO nanoparticles (NPs) with a granular morphology were synthesized using a hydrothermal method. Structural analysis revealed that ZnO NPs had a single crystal wurtzite hexagonal structure. Solvent polarity was responsible for varying and controlling their size and morphology. The process was very trouble free and scalable. In addition, it could be used for fundamental studies on tunable morphology formation. This hydrothermal method showed different morphology with different co-surfactants such as a floral-like or wire-like belt sheet structures etc. Based on their surface morphology, the same material had different applications as a catalyst in various organic reactions and also could be used as a photocatalyst and fuel cell, solar cell or in semiconductors etc. X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy and photoluminescence of the resulting product was performed to study its purity, morphology and size, plus its optical properties via measurement of band gap energy and light absorbance.

Citrate-Induced Nanocubes: A Re-Examination of the Role of Citrate as a Shape-Directing Capping Agent for Ag-Based Nanostructures.

Seed-mediated syntheses utilizing facet-selective surface passivation provide the necessary chemical controls to direct noble metal nanostructure formation to a predetermined geometry. The foremost protocol for the synthesis of (111)-faceted Ag octahedra involves the reduction of metal ions onto pre-existing seeds in the presence of citrate and ascorbic acid. It is generally accepted that the capping of (111) facets with citrate dictates the shape while ascorbic acid acts solely as the reducing agent. Herein, a citrate-based synthesis is demonstrated in which the presence or absence of ascorbic acid is the shape-determining factor. Reactions are carried out in which Ag(+) ions are reduced onto substrate-immobilized Ag, Au, Pd, and Pt seeds. Syntheses lacking ascorbic acid, in which citrate acts as both the capping and the reducing agent, result in a robust nanocube growth mode able to withstand wide variations in the concentration of reactants, reaction rates, seed material, seed orientation and faceting, pH, and substrate material. If, however, ascorbic acid is included in these syntheses, then the growth mode reverts to one that advances the octahedral geometry. The implication of these results is that citrate, or one of its oxidation products, selectively caps (100) facets, but where this capability is compromised by ascorbic acid.

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.