Determination of phenol by flow-injection with chemiluminescence detection based on the hemin-catalysed luminol-hydrogen peroxide reaction

Innovative Fe(IV)-Triggered Chemiluminescence Assay for Rapid and Selective Detection of Total Phenolic Content

Total phenolic content reflecting the overall concentration of phenolics in water is a valuable indicator for evaluating water quality. However, current total phenolic content quantification technologies are unsatisfactory due to their complexity, time-consuming nature, limited reliability, and low selectivity. To overcome these problems, we utilized the high reactivity and selectivity of tetravalent iron (Fe(IV)) toward phenolics to develop a surrogate method for total phenolic content based on the quenching effect of phenolics on the chemiluminescence (CL) produced during the oxidation of naproxen (NAP) by Fe(IV) in the Fe(II)-activated periodate (Fe(II)/PI) process. Experimental results showed a strong linear relationship between the chemiluminescence quenching capacity (CLQC) values and total phenolic content in the Fe(II)/PI-NAP process. The high reactivity and superior selectivity of Fe(IV) toward phenolics enable rapid, highly sensitive, and robust anti-interference quantification of total phenolic content using the developed CL method. The limit of quantitation and limit of detection of the developed CL method for total phenolics determination were 1.34 and 0.40 μM, respectively, expressed as phenol equivalents. Finally, we validated the feasibility of using the CLQC value as a surrogate indicator for total phenolic content in various real water samples. This work introduces a novel method for quantifying total phenolic content by determining the CLQC value of water samples using the Fe(II)/PI-NAP process, offering a promising alternative for controlling the discharge of phenolics.

Ferrocene/ β-cyclodextrin based supramolecular nanogels as theranostic systems

A supramolecular redox responsive nanogel (NG) with the ability to sense cancer cells and loaded with a releasing therapeutic agent was synthesized using hostguest interactions between polyethylene glycol-grafted-β-cyclodextrin and ferrocene boronic acid. Cyclic voltammetry matched with other spectroscopy and microscopy methods provided strong indications regarding host-guest interactions and formation of the NG. Moreover, the biological properties of the NG were evaluated using fluorescence silencing, confocal laser scanning microscopy, and cell toxicity assays. Nanogel with spherical core-shell architecture and 100-200 nm sized nanoparticles showed high encapsulation efficiency for doxorubicin (DOX) and luminol (LU) as therapeutic and sensing agents. High therapeutic and sensing efficiencies were manifested by complete release of DOX and dramatic quenching of LU fluorescence triggered by 0.05 mM H2O2 (as an ROS component). The NGs showed high ROS sensitivity. Taking advantage of a high loading capacity, redox sensitivity, and biocompatibility, the NGs can be used as strong theranostic systems in inflammation-associated diseases.

Water-soluble Hemin-mPEG-enhanced Luminol Chemiluminescence for Sensitive Detection of Hydrogen Peroxide and Glucose

In the present study, we synthesized a water-soluble substance (Hemin-mPEG) at room temperature by using hemin and poly(ethylene glycol) methyl ether (mPEG). It was found that the Hemin-mPEG maintained the excellent catalytic activity inherited from hemin, and was first used to catalyze a luminol-H₂O₂ chemiluminescence (CL) system to generate an intense and slow CL signal. The results of a mechanism research showed that the presence of Hemin-mPEG could promote the production of oxygen-relative radicals from H₂O₂ and dissolved oxygen in solution. Based on this mechanism, an ultra-sensitive, cheap and simply practical sensor for detecting glucose and H₂O₂ was developed. Under the most optimal experimental conditions, H₂O₂ and glucose detection results exhibited a good linear range from 0.002 to 3 μM and from 0.02 to 4 μM, respectively, and the detection limits were 1.8 and 10 nM, respectively. This approach has been successfully used to detect glucose in actual biological samples, and achieved good results.

Flow analysis with chemiluminescence detection: Recent advances and applications

This article highlights the most important developments in flow analysis with chemiluminescence (CL) detection, describing different flow systems that are compatible with CL detection, detector designs, commonly applied CL reactions and approaches to sample treatment. Recent applications of flow analysis with CL detection (focusing on outputs published since 2010) are also presented. Applications are classified by sample matrix, covering foods and beverages, environmental matrices, pharmaceuticals and biological fluids. Comprehensive tables are provided for each area, listing the specific sample matrix, CL reaction used, linear range, limit of detection and sample treatment for each analyte. Finally, recent and emerging trends in the field are also discussed.

DPPH·-luminol chemiluminescence system and its application in the determination of scutellarin in pharmaceutical injections and rat plasma with flow injection analysis

In this article, a DPPH·-luminol chemiluminescence (CL) system was reported and the CL mechanism was discussed according to the CL kinetic properties after sequence injecting DPPH· into the DPPH·-luminol reaction mixture. It was observed that scutellarin could inhibit the CL response of the DPPH·-luminol system. Based on this observation, a simple and rapid flow injection CL method was developed for the determination of scutellarin using the inhibition effect in alkaline medium. The optimized chemical conditions for the CL reaction were 5 × 10^-6  mol/L DPPH· and 1.0 × 10^-4  mol/L luminol in 0.01 mol/L NaOH. Under optimized conditions, the CL intensity was inversely proportional to the concentration of scutellarin over the ranges 5-2000 and 40-3200 ng/ml in pharmaceutical injection and rat plasma, respectively. The limits of detection (S/N = 3) were 5 and 40 ng/ml in preparations and rat plasma, respectively. Furthermore, the precision, recovery and stability of the validated method were acceptable for the determination of scutellarin in both pharmaceutical injections and rat plasma. The presented method was successfully applied in the determination of scutellarin in pharmaceutical injections and real rat plasma samples.

Highly-sensitive electrocatalytic determination for toxic phenols based on coupled cMWCNT/cyclodextrin edge-functionalized graphene composite

Highly-sensitive electrocatalytic determination of toxic phenol compounds is of significance in environmental monitoring due to their low degradation and high toxicity to the environment and humans. In this paper, a rapid and sensitive electrochemical sensor based on coupled carboxyl-multi-walled carbon nanotube (cMWCNT) and cyclodextrin (CD) edge-functionalized graphene composite was successfully employed towards trace detection of three typical phenols (4-aminophenol, 4-AP; 4-chlorophenol, 4-CP; 4-nitrophenol, 4-NP). The morphology studies from scanning electron microscope and transmission electron microscope analysis revealed that cMWCNTs as conductive bridges were successfully incorporated into CD edge-functionalized graphene layers. Further, The electrocatalytic detection performance of the 3D simultaneously reduced and self-assembled sensing architecture (GN-CD-cMWCNT) with trace amounts of CDs was evaluated. The electrochemical studies demonstrated that GN-CD-cMWCNT displays excellent electrocatalytic activity, high sensitivity and stability. Under optimal conditions, the current responses of 4-AP, 4-CP and 4-NP are linear to concentrations over two different ranges, with low detection limit of 0.019, 0.017 and 0.027μM (S/N=3), respectively. And, GN-CD-cMWCNT shows an excellent anti-interference ability against electroactive species and metal ions. In addition, validation of the applicability of the presented sensor was also performed for the determination of three phenols in tap water sample with satisfactory results.

High chemiluminescence activity of an FeIII–TAML activator in aqueous–organic media and its use in the determination of organic peroxides

Using Fe^III–TAML, highly active peroxidase mimic, the sensitive chemiluminescence assays for the determination of benzoyl peroxide and tert-butyl hydroperoxide in the presence of organic solvents were developed.

Comparison of uric Acid quantity with different food in human urine by flow injection chemiluminescence analysis

Based on the inhibitory effect of uric acid (UA) on luminol-Co(2+) chemiluminescence (CL) system, a sensitive method for the determination of UA at nanomolar level by flow injection (FI) CL was proposed. The proposed method was successfully applied to real-time monitoring of UA excretion in human 24 h urine with different food intake, showing that meats, vegetables, and porridge intake caused differential UA excretions of 879, 798, and 742 mg, respectively. It was also found that UA concentrations in urine under the three kinds of food intake simultaneously reached maximum at 2 h after meals with the values of 417, 318, and 288 μg mL(-1), respectively. The UA concentration in human serum was also determined by this approach, and the possible mechanism of luminol-Co(2+)-UA CL reaction was discussed in detail.

Naked eye screening of 11 phenolic compounds and colorimetric determination using polydiacetylene vesicles with α-cyclodextrin

The colorimetric response (CR) of poly(10,12-pentacosadiynoic acid) vesicles (PPCDA) induced by α-cyclodextrin (α-CD) in an aqueous solution has been studied. Various parameters affecting the CR, such as response time and concentration were investigated. The blue color of 0.01 mM PPCDA solution became pinkish red with the addition of α-CD at the concentration higher than 3 mM. The inhibition of the color transition from blue to red was investigated using 11 phenolic compounds. The color transition could be inhibited and observed by naked eye in the presence of 4 phenolic compounds, i.e. 4-nitrophenol (4-NP) and 4-bromophenol (4-BP) and 4-chlorophenol (4-CP) and 3-nitrophenol (3-NP). A colorimetric method for the determination of these compounds was validated and applied for surface water analysis. The linear range from the plot of CR against phenolic compounds concentration was in the order of 0.5-2.0 mM with R(2) more than 0.99. The recoveries were 90-95% with good precision (1-4%RSD, n=10).