Recent advances in poly(ionic liquid)s for biomedical application

Poly(ionic liquid)s (PILs) are polymers containing ions in their side-chain or backbone, and the designability and outstanding physicochemical properties of PILs have attracted widespread attention from researchers. PILs have specific characteristics, including negligible vapor pressure, high thermal and chemical stability, non-flammability, and self-assembly capabilities. PILs can be well combined with advanced analytical instruments and technology and have made outstanding contributions to the development of biomedicine aiding in the continuous advancement of science and technology. Here we reviewed the advances of PILs in the biomedical field in the past five years with a focus on applications in proteomics, drug delivery, and development. This paper aims to engage pharmaceutical and biomedical scientists to full understand PILs and accelerate the progress from laboratory research to industrialization.

Electrochemical (bio) sensors go green

Electrochemical (bio) sensors are now widely acknowledged as a sensitive detection tool for disease diagnosis as well as the detection of numerous species of pharmaceutical, clinical, industrial, food, and environmental origin. The term 'green' demonstrates the development of electrochemical (bio) sensing platforms utilizing biodegradable and sustainable materials. Development of green sensing platforms is one of the most active areas of research minimizing the use of toxic/hazardous reagents and solvent systems, thereby further reducing the production of chemical wastes in sensor fabrication. The present review includes green electrochemical (bio) sensors which are based on firstly, green sensors comprising natural and non-hazardous materials (e.g., paper/clay/zeolites/biowastes), secondly sensors based on nanomaterials synthesized by green methods and lastly sensors constituting green solvents (e.g., ionic liquids/deep eutectic solvents). Electrochemical performances of such green sensors and their benefits such as biodegradability, non-toxicity, sustainability, low-cost, sensitive surfaces, etc. Have been discussed for quantification of various target analytes. Associated challenges, possible solutions, and opportunities towards fabricating green electrochemical sensors and biosensors have been provided in the conclusion section.

Poly(ionic liquid) composites

This review highlights recent advances in the development of poly(ionic liquid)-based composites for diverse materials applications.

A Cross-Linker-Based Poly(Ionic Liquid) for Sensitive Electrochemical Detection of 4-Nonylphenol

In this study, we report a cross-linker-based poly(ionic liquid) (PIL) for the sensitive detection of 4-nonylphenol (4-NP). PIL was poly(1,4-butanediyl-3,3′-bis-l-vinylimidazolium dibromide) (poly([V₂C₄(mim)₂]Br₂)). Poly([V₂C₄(mim)₂]Br₂) was prepared via one-step free-radical polymerization. The poly([V₂C₄(mim)₂]Br₂) was characterized by infrared spectroscopy, Raman spectroscopy, thermal gravimetric analyzer and scanning electron microscope. The poly([V₂C₄(mim)₂]Br₂) was then drop-cast onto a glassy carbon electrode (GCE) to obtain poly([V₂C₄(mim)₂]Br₂)/GCE. In comparison with a bare GCE, poly([V₂C₄(mim)₂]Br₂)/GCE exhibited higher peak current responses for [Fe(CN)₆]^3−/4−, lower charge transfer resistance, and larger effective surface area. While comparing the peak current responses, we found the peak current response for 4-NP using poly([V₂C₄(mim)₂]Br₂)/GCE to be 3.6 times higher than a traditional cross-linker ethylene glycol dimethacrylate (EGDMA) based poly(EGDMA) modified GCE. The peak current of poly([V₂C₄(mim)₂]Br₂) sensor was linear to 4-NP concentration from 0.05 to 5 μM. The detection limit of 4-NP was obtained as 0.01 μM (S/N = 3). The new PIL based electrochemical sensor also exhibited excellent selectivity, stability, and reusability. Furthermore, the poly([V₂C₄(mim)₂]Br₂)/GCE demonstrated good 4-NP detection in environmental water samples.

Simultaneous determination of β-agonists on hexagonal boron nitride nanosheets/multi-walled carbon nanotubes nanocomposite modified glassy carbon electrode

β-Agonists are illegally consumed in various products such as food and animal and effect the nutrition distribution owing to change of body fat. In addition, they result in acute poisoning and several symptoms such as muscular tremors and nervousness. A new electrochemical approach based on two-dimensional hexagonal boron nitride (2D-hBN) nanosheets decorated functionalized multi-walled carbon nanotubes (f-MWCNTs) was presented for simultaneous determination of β-agonists such as phenylethanolamine A (PEA), clenbuterol (CLE), ractopamine (RAC) and salbutamol (SAL) in urine samples. X-ray diffraction (XRD) method, Raman spectroscopy, scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used characterizations of nanomaterials. After that, 2D-hBN/f-MWCNTs nanocomposite modified glassy carbon electrode (GCE) was prepared for simultaneous determination of β-agonists. 1.0 × 10^-12-1.0 × 10^-8 M and 1.0 × 10^-13 M were founded as the linearity range and the detection limit (LOD) for PEA, CLE, RAC and SAL. Finally, the prepared electrochemical sensor was used for urine sample analysis in presence of ascorbic acid (AA) and uric acid (UA).

Frontiers in poly(ionic liquid)s: syntheses and applications

We review recent works on the synthesis and application of poly(ionic liquid)s (PILs). Novel chemical structures, different synthetic strategies and controllable morphologies are introduced as a supplement to PIL systems already reported. The primary properties determining applications, such as ionic conductivity, aqueous solubility, thermodynamic stability and electrochemical/chemical durability, are discussed. Furthermore, the near-term applications of PILs in multiple fields, such as their use in electrochemical energy materials, stimuli-responsive materials, carbon materials, and antimicrobial materials, in catalysis, in sensors, in absorption and in separation materials, as well as several special-interest applications, are described in detail. We also discuss the limitations of PIL applications, efforts to improve PIL physics, and likely future developments.

A selective and sensitive nanosensor for fluorescent detection of specific IgEs to purified allergens in human serum

Food allergies are increasingly recognized as a major healthcare concern. In order to sensitively and specifically detect allergies from blood samples of at-risk allergic patients, an effective magnetic fluorescence sensing platform (EMFP) was constructed. The EMFP incorporated hollow mesoporous silica nanospheres (HMNs) to amplify signal from the target IgE in addition to magnetic nanoparticles (MNPs) to capture and separate the target IgE. The application of EMFP to immunoassays indicated a detection limit of 0.0159 ng mL⁻¹ for low concentration specific immunoglobulin E (sIgE) against purified shellfish Metapenaeus ensis (Meta. E.) allergens, which is 15 fold more sensitive than the commercially available Food and Drug Administration-approved analyzers. Notably, EMFP was specific for the targeted sIgE even with interference by other sIgEs. In addition, the detection time is only 75 min, considerably faster than current commercial ELISA kits for IgE assays. Together, these results demonstrated that EMFP has excellent sensitivity and selectivity for the rapid detection of sIgE. The method thus exhibits potential toward the rapid monitoring of sIgE against Meta. E. allergens in clinical application.

The effective magnetic fluorescence sensing platform was employed to amplify signal and capture target IgE in one step.

Novel imidazole fluorescent poly(ionic liquid) nanoparticles for selective and sensitive determination of pyrogallol

This paper reports novel imidazole fluorescent poly(ionic liquid) nanoparticles (FPILNs) of poly(1-[(4-methyphenyl)methyl]-3-vinyl-imidazolium bromide (poly([MVI]Br) for selective and sensitive determination of pyrogallol. An imidazole ionic liquid of 1-[(4-methyphenyl)methyl]-3-vinyl-imidazolium bromide ([MVI]Br) was synthesized and used as the only monomer to obtain poly([MVI]Br) possessing phenyl fluorophores using a radical polymerization technique. The obtained poly([MVI]Br) can form nanoparticles in water. Scanning electron microscopy and dynamic light scattering results revealed majority of poly([MVI]Br) FPILNs with diameters ranging from 40 to 400nm. Although [MVI]Br showed weak fluorescence intensity, poly([MVI]Br) FPILNs exhibited strong fluorescence intensity with a quantum yield of 0.192, which is attributed to the presence of significant number of phenyl fluorophores and rigid construction. The selective and sensitive determination of pyrogallol was achieved through fluorescence quenching of poly([MVI]Br) FPILNs, and the quenching was attributed to the oxidation of poly([MVI]Br) FPILNs by O₂˙¯ produced by pyrogallol autoxidation. The poly([MVI]Br) FPILNs-based sensor demonstrated a good linear relationship between the extent of fluorescence quenching and the concentration of pyrogallol in a range of 0.05 - 10.0μM, achieving a detection limit of 0.01μM. Furthermore, the poly([MVI]Br) FPILNs-based assay detected pyrogallol in environmental water samples, suggesting its potential to be applied for practical purposes.

Development of a highly sensitive and specific monoclonal antibody based enzyme-linked immunosorbent assay for the detection of a new β-agonist, phenylethanolamine A, in food samples

BACKGROUND

All β-agonists are banned as feed additives for growth promotion in animals due to toxic effects on humans after consuming the β-agonist contaminated meats. Phenylethanolamine A (PA) is a newly emerged β-agonist. Thus there is a need to develop highly sensitive and specific analytical methods for the detection of PA in food samples. In this study, the monoclonal antibody (mAb) against PA was produced by hybridoma technology and used for the development of enzyme-linked immunosorbent assay (ELISA).

RESULTS

The IC₅₀ values and limits of detection (LODs) of the ELISA using homogeneous combination of coating antigen/antibody for PA were 0.16 ng mL^-1 and 0.011 ng mL^-1 , respectively. The cross-reactive (CR) values of the assay with 14 structurally related β-agonists were lower than 0.59%. Swine liver and meat samples were spiked with PA at different content and analysed by ELISA. Acceptable recovery rates of 91.40-105.51% and intra-assay coefficients of variation of 1.56-9.92% (n = 3) were obtained. The ELISA for seven spiked samples was confirmed by LC-MS/MS with a high correlation coefficient of 0.9881.

CONCLUSION

The proposed mAb-based ELISA was highly sensitive and specific for PA and could be used as a quantitative/screening method for PA analysis in food samples. © 2016 Society of Chemical Industry.

Controllable synthesis and enhanced gas sensing properties of a single-crystalline WO3–rGO porous nanocomposite

A single-crystalline WO₃–rGO composite has been successfully prepared and applied into gas detection. Impressively, this permit-3D porous nanostructures display enhanced NO₂ sensing properties.

Significant enhancement of visible light photocatalytic activity of the hybrid B12-PIL/rGO in the presence of Ru(bpy)32+ for DDT dehalogenation

A new hybrid catalyst, B₁₂-PIL/rGO, was prepared. It exhibited enhanced photocatalytic activity for DDT dechlorination in the presence of Ru(bpy)₃²⁺.

Graphene-based nanoprobes for molecular diagnostics

In recent years, graphene has received widespread attention owing to its extraordinary electrical, chemical, optical, mechanical and structural properties. Lately, considerable interest has been focused on exploring the potential applications of graphene in life sciences, particularly in disease-related molecular diagnostics. In particular, the coupling of functional molecules with graphene as a nanoprobe offers an excellent platform to realize the detection of biomarkers, such as nucleic acids, proteins and other bioactive molecules, with high performance. This article reviews emerging graphene-based nanoprobes in electrical, optical and other assay methods and their application in various strategies of molecular diagnostics. In particular, this review focuses on the construction of graphene-based nanoprobes and their special advantages for the detection of various bioactive molecules. Properties of graphene-based materials and their functionalization are also comprehensively discussed in view of the development of nanoprobes. Finally, future challenges and perspectives of graphene-based nanoprobes are discussed.