A highly sensitive detection of chloramphenicol based on chemiluminescence immunoassays with the cheap functionalized Fe3O4@SiO2 magnetic nanoparticles

A strategy has been applied to chloramphenicol (CAP) detection with chemiluminescence immunoassays (CLIA) based on cheap functionalized Fe₃O₄@SiO₂ magnetic nanoparticles (Fe–MNPs). The strategy that bovine serum albumin (BSA) was immobilized on cheap functionalized Fe–MNPs and that the CAP molecules were then immobilized on BSA, avoided the long process of dialysis for preparation of the BSA‐CAP conjugates. The samples were detected for both methods that utilized two different kinds of functionalized Fe–MNPs (amine‐functionalized Fe₃O₄@SiO₂ and carboxylic acid‐functionalized Fe₃O₄@SiO₂). The sensitivities and limits of detection (LODs) of the two methods were obtained and compared based on inhibition curves. The 50% inhibition concentrations (IC₅₀) values of the two methods were about 0.024 ng ml^?1 and 0.046 ng ml^?1 respectively and LODs were approximately 0.0002 ng ml^?1 and 0.001 ng ml^?1 respectively. These methods were much more sensitive than that of any traditional enzyme‐linked immunosorbent assay (ELISA) previously reported. Therefore, such chemiluminescence methods could be easily adapted for small molecule detection in a variety of foods using Fe–MNPs.     

Determination of fluvoxamine maleate in human urine and human serum using alkaline KMnO4–rhodamine B chemiluminescence

The flow‐injection chemiluminescence (FI‐CL) behavior of a gold nanocluster (Au NC)–enhanced rhodamine B–KMnO₄ system was studied under alkaline conditions for the first time. In the present study, the as‐prepared bovine serum albumin‐stabilized Au NCs showed excellent stability and reproducibility. The addition of trace levels of fluvoxamine maleate (Flu) led to an obvious decline in CL intensity in the rhodamine B–KMnO₄–Au NCs system, which could be used for quantitative detection of Flu. Under optimized conditions, the proposed CL system exhibited a favorable analytical performance for Flu determination in the range 2 to 100 μg ml^?1. The detection limit for Flu measurement was 0.021 μg ml^?1. Moreover, this newly developed system revealed outstanding selectivity for Flu detection when compared with a multitude of other species, such as the usual ions, uric acid and a section of hydroxy compounds. Additionally, CL spectra, UV–visible spectroscopes and fluorescence spectra were measured in order to determine the possible reaction mechanism. This approach could be used to detect Flu in human urine and human serum samples with the desired recoveries and could have promising application under physiological conditions.     

One-step homogeneous non-stripping chemiluminescence metal immunoassay based on catalytic activity of gold nanoparticles

The catalytic activity of gold nanoparticles (AuNPs) on a luminol–H₂O₂ chemiluminescence (CL) system is found to be greatly enhanced after its crosslinking aggregation induced by immunoreaction. Based on this observation, a one-step homogeneous non-stripping CL metalloimmunoassay was designed. In the presence of corresponding antigen (Ag), the immunoreaction caused the aggregation of antibody (Ab)-modified AuNPs, and these crosslinking aggregated AuNPs could catalyze luminol–H₂O₂ CL reaction to produce a much stronger CL signal than dispersed Ab-modified AuNPs. The assay, including immunoreaction and detection, can be accomplished in homogeneous solution. In the assay, no tedious and strict stripping of metal nanoparticles, difficult synthesis of labels, multiple steps of immunoreactions and washings, and complicated magnetic separation process were required. The detection limit of human immunoglobulin G (IgG, 3σ) was estimated to be as low as 3.2 × 10⁻¹¹ g ml⁻¹. The sensitivity was increased by two orders of magnitude over that of other AuNP-based CL immunoassay. The current CL metalloimmunoassay offers the advantages of being simple, cheap, rapid, and sensitive.     

Development of chemiluminescence method for determination of 10‐hydroxycamptothecin based on luminol–[Ag(HIO6)2]5− reaction in alkaline solution

A novel chemiluminescence (CL) method was developed for the determination of 10‐hydroxycamptothecin(HCPT) based on the CL reaction between [Ag(HIO₆)₂]^5? and luminol in alkaline solution. CL emission of Ag(III) complex–luminol in alkaline medium was very different from that in acidic medium. A possible mechanism of enhanced CL emission was suggested. The enhanced effect of HCPT on CL emission of the [Ag(HIO₆)₂]^5?–luminol system was found. The enhanced degree of CL emission was proportional to HCPT concentration. The effect of the reaction conditions on CL emission was examined. Under optimal conditions, the limit of detection was 6.5 × 10^?9 g mL^?1. The proposed method was applied for the determination of HCPT in real samples with the recoveries of 93.2–109% with the RSD of 1.7–3.3%. Copyright © 2010 John Wiley & Sons, Ltd.     

Ultrasensitive chemiluminescence assay for cimetidine detection based on the synergistic improving effect of Au nanoclusters and graphene quantum dots

A novel and sensitive chemiluminescence (CL) procedure based on the synergetic catalytic effects of gold nanoclusters (Au NCs) and graphene quantum dots (GQDs) was developed for the reliable measurement of cimetidine (CM). The initial experiments showed that the KMnO₄‐based oxidation of alkaline rhodamine B (RhoB) generated a very weak CL emission, which was intensively enhanced in the simultaneous presence of Au NCs and GQDs. CL intermediates can be adsorbed and gathered on the surface of Au NCs, becoming more stable. GQDs participate in the energy transferring processes and facilitate them. These improving effects were simultaneously obtained by adding both Au NCs and GQDs into the RhoB‐KMnO₄ reaction. Consequently, the increasing effect of the Au NCs/GQDs mixture was more than that of pure Au NCs or GQDs, and a new nano‐assisted powerful CL system was achieved. Furthermore, a marked quenching in the emission of the introduced CL system was observed in the presence of CM, so the system was examined to design a sensitive sensor for CM. After optimization of influencing parameters, the linear lessening in CL emission intensity of KMnO₄‐RhoB‐Au NCs/GQDs was verified for CM concentrations in the range 0.8–200 ng ml^?1. The limit of detection (3S_b/m) was 0.3 ng ml^?1. Despite being a simple CL method, good sensitivity was obtained for CM detection with reliable results for CM determination in human urine samples.     

Prospects for using a new sequential chemiluminescence strategy for monitoring the caffeine content in soft and energy drinks via the catalytic activities of different nano‐metal oxides

This article suggests a new sequential injection analysis chemiluminescence (SIA‐CL) strategy for monitoring the caffeine (CAF) content in soft and energy drinks using the catalytic activities of different nano‐metal oxides. The present study describes three different SIA‐CL systems (luminol–ferricyanide (III) coupled with Fe₂O₃ or ZnO nanoparticles (NPs), and luminol–H₂O₂ coupled with CuONPs. All experimental conditions were optimized and the linear concentration ranges of pure CAF were evaluated using the calibration graphs. The selectivity of the developed SIA‐CL systems was studied under the influence of various interfering species that may be present in soft or energy drinks such as sodium ions, sucrose, glucose, sodium benzoate, sodium citrate, riboflavin, niacin, citric, phosphoric and ascorbic acids. International Council for Harmonization (ICH) guidelines were obeyed for the validation of the suggested CL methods. The developed SIA‐CL systems displayed linear relationships over the concentration ranges 1.0–350, 5.0–400 and 10.0–400 μg ml^?1 with Fe₂O₃ NPs, ZnO NPs and CuO NPs, respectively. The recorded lower limits of detection and quantification were 0.7, 2.7 and 7.8 μg ml^?1, and 1.0, 5.0 and 10.0 μg ml^?1 for the previously mentioned SIA‐CL systems. The results revealed high selectivity for CAF determination and were in good agreement with those obtained by other reported methods.     

Simultaneous Detection of Forbidden Chemical Residues in Milk Using Dual-Label Time-Resolved Reverse Competitive Chemiluminescent Immunoassay Based on Amine Group Functionalized Surface

In this study, a sensitive dual-label time-resolved reverse competitive chemiluminescent immunoassay was developed for simultaneous detection of chloramphenicol (CAP) and clenbuterol (CLE) in milk. The strategy was performed based on the distinction of the kinetic characteristics of horseradish peroxidase (HRP) and alkaline phosphatase (ALP) in chemiluminesecence (CL) systems and different orders of magnitude in HRP CL value for CAP and ALP CL value for CLE in the chemiluminescent immunoassay. Capture antibodies were covalently bound to the amine group functionalized chemiluminescent microtiter plate (MTP) for efficient binding of detection antibodies for the enzymes labeled CAP (HRP-CAP) and CLE (ALP-CLE). The CL signals were recorded at different time points by the automatic luminometers with significant distinction in the dynamic curves. When we considered the ALP CL value (about 10⁵) of CLE as background for HRP CL signal value (about 10⁷) of CAP, there was no interaction from ALP CL background of CLE and the differentiation of CAP and CLE can be easily achieved. The 50% inhibition concentration (IC₅₀) values of CAP and CLE in milk samples were 0.00501 µg L⁻¹ and 0.0128 µg L⁻¹, with the ranges from 0.0003 µg L⁻¹ to 0.0912 µg L⁻¹ and from 0.00385 µg L⁻¹ to 0.125 µg L⁻¹, respectively. The developed method is more sensitive and of less duration than the commercial ELISA kits, suitable for simultaneous screening of CAP and CLE.     

Highly luminescent S,N co‐doped carbon quantum dots‐sensitized chemiluminescence on luminol–H2O2 system for the determination of ranitidine

S,N co‐doped carbon quantum dots (N,S‐CQDs) with super high quantum yield (79%) were prepared by the hydrothermal method and characterized by transmission electron microscopy, photoluminescence, UV–Vis spectroscopy and Fourier transformed infrared spectroscopy. N,S‐CQDs can enhance the chemiluminescence intensity of a luminol–H₂O₂ system. The possible mechanism of the luminol–H₂O₂–(N,S‐CQDs) was illustrated by using chemiluminescence, photoluminescence and ultraviolet analysis. Ranitidine can quench the chemiluminescence intensity of a luminol–H₂O₂–N,S‐CQDs system. So, a novel flow‐injection chemiluminescence method was designed to determine ranitidine within a linear range of 0.5–50 μg ml^?1 and a detection limit of 0.12 μg ml^?1. The method shows promising application prospects.     

Chemiluminescence selectivity enhancement in the on‐chip Ru(bpy)32+ system: The potential role of buffer type and pH in the determination of hydrochlorothiazide in combined formulations and human plasma

A simple and highly selective on‐chip Ru(bpy)₃²⁺–oxidant chemiluminescence (CL) approach for estimation of a diuretic drug, hydrochlorothiazide (HCZ), in biological fluids was realized in the presence of other fixed‐dose combination drugs by manipulating simultaneously the method of active species (Ru(bpy)₃³⁺) production and type of carrier buffer with pH used for the CL reaction. Chemical oxidation processes involved in the Ru(bpy)₃²⁺–Ce(IV) CL system have been successfully miniaturised in this study using a microfabricated device to generate Ru(bpy)₃³⁺ instantaneously. The proposed system was then screened using HCZ and other drugs in the presence of various buffers and pH to explore the difference in CL emission. Ammonium formate buffer (0.15 M) at pH 4.5 exhibited excellent selectivity towards HCZ when Ru(bpy)₃³⁺ was produced by chemical oxidation using Ce(IV). The newly developed conditions do not involve any kind of prior separation or isolation procedure to remove other combination therapy drugs in formulation and biological samples. The method under fully optimised conditions exhibited wide linearity over the concentration range 0.5–1000 ng ml^?1 and low detection and quantification limits of 0.13 and 0.47 ng ml^?1 respectively for HCZ. Acceptable levels of recoveries were obtained for HCZ from human plasma using the proposed method (98.9–100.8%) in the presence of other antihypertensive combination therapy drugs. This study postulates that such miniaturised devices may find applications especially for on‐site analysis, such as doping control examinations.     

Chemiluminescence assay for Listeria monocytogenes based on Cu/Co/Ni ternary nanocatalyst coupled with penicillin as generic capturing agent

Bacterial pathogen control is important in seafood production. In this study, a Cu/Co/Ni ternary nanoalloy (Cu/Co/Ni TNA) was synthesized using the oleylamine reducing method. It was found that Cu/Co/Ni TNA greatly enhanced the chemiluminescence (CL) signal of the hydroxylamine‐O‐sulfonic acid (HOSA)–luminol system. The CL properties of Cu/Co/Ni TNA were investigated systemically. The possible CL mechanism also was intensively investigated. Based on the enhanced CL phenomenon of Cu/Co/Ni TNA, a Cu/Co/Ni TNA, penicillin, and anti‐L. monocytogenes (Listeria monocytogenes) antibody‐based sandwich complex assay for detection of L. monocytogenes was established. In this sandwich CL assay, penicillin was employed to capture and enrich pathogenic bacteria with penicillin‐binding proteins (PBPs) while anti‐L. monocytogenes antibody was adopted as the specific recognition molecule to recognize L. monocytogenes. L. monocytogenes was detected sensitively based on this new Cu/Co/Ni TNA–HOSA–luminol CL system. The CL intensity was proportional to the L. monocytogenes concentration ranging from 2.0 × 10² CFU ml^?1 to 3.0 × 10⁷ CFU ml^?1 and the limit of detection wa 70 CFU ml^?1. The reliability and potential applications of our method was verified by comparison with official methods and recovery tests in environment and food samples.     

A novel method for sensing of methimazole using gold nanoparticle‐catalyzed chemiluminescent reaction

Based on the inhibition effect of methimazole (MMI) on the reaction of luminol–H₂O₂ catalyzed by gold nanoparticles, a novel chemiluminescence (CL) method was developed for the determination of MMI. Under the optimum conditions, the relative CL intensity was linearly related to MMI concentration in the range from 5.0 × 10^?8 to 5.0 × 10^?5 mol L^?1. The detection limit was 1.6 × 10^?8 mol L^?1 (S/N = 3), and the RSD for 6.0 × 10^?6 mol L^?1 MMI was 4.83 (n = 11). This method has high sensitivity, wide linear range, inexpensive instrumentation and has been applied to detect MMI in pharmaceutical tablets and pig serum samples. Furthermore, a possible reaction mechanism is discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

New luminol chemiluminescence reaction using diperiodatoargentate as oxidate for the determination of amikacin sulfate

A new chemiluminescence (CL) reaction between luminol and diperiodatoargentate {K₂ [Ag (H₂IO₆) (OH) ₂]} was observed in alkaline medium. The CL intensity could be greatly enhanced by amikacin sulfate. Therefore a new CL method for the determination of amikacin sulfate was built by combining with flow injection technology. A possible mechanism of the CL reaction was proposed via the investigation of the CL kinetic characteristics, the CL spectrum and the UV absorption spectra of some related substance. The concentration range of linear response was 5.1 × 10^?8 to 5.1 × 10^?6 mol L^?1 with a detection limit of 1.9 × 10^?8 mol L^?1 (3σ). The proposed method had good reproducibility with a relative standard deviation of 2.8% (n = 7) for 5.1 × 10^?7 mol L^?1 of amikacin sulfate. It was successfully applied to determine amikacin sulfate in serum. Copyright © 2009 John Wiley & Sons, Ltd.     

Analysis of methylparaben in cosmetics based on a chemiluminescence H2O2−NaIO4−CNQDs system

In this article, a simple, effective chemiluminescence (CL) method for the detection of methylparaben (MP) in cosmetic samples was developed based on an IO₄^?–H₂O₂–carbon nitrogen quantum dots (CNQDs) system without a separation process. The results indicated that the redox reaction between periodate and hydrogen peroxide released hydroxide radicals and superoxide radical anions in the presence of bicarbonate. These two radicals were responsible for the formation of excited luminophor CNQD* with a maximum wavelength at 480 nm. Due to the competitive reaction with hydroxide radicals, CL intensity was markedly diminished in the presence of MP. The relative standard deviation in the intraday assay was below 5.5% (n = 9), and the detection limit was as low as 0.50 μmol/L. The proposed method allowed for the successful, selective determination of MP in cosmetics.     

A chemiluminescent metalloimmunoassay based on copper‐enhanced gold nanoparticles for quantification of human growth hormone

A chemiluminescence (CL) immunoassay was developed to determine human growth hormone (hGH) based on copper‐enhanced gold nanoparticles. In this method, gold nanoparticles were deposited on polystyrene wells for adsorption of human growth antibodies as well as catalyst for reducing of copper ions from the copper enhancer solution. The reduction of copper ions was prevented where the gold nanoparticles were covered by the antibody–antigen immunocomplex. The deposited copper on Au nanoparticles was then dissolved in HNO₃ solution and quantified using the CL method. The CL intensity response was logarithmically dependent on the hGH concentrations over the range 0.2–50 ng/mL, with a detection limit (3σ) of 0.036 ng/mL. Copyright © 2012 John Wiley & Sons, Ltd.     

Chemiluminescent assay of alkaline phosphatase using dihydroxyacetone phosphate as substrate detected with lucigenin

A sensitive and simple chemiluminescent assay (CL) for alkaline phosphatase (ALP) using dihydroxyacetone phosphate or its ketal (DHAP or DHAP‐ketal) was developed. New substrates were transformed to dihydroxyacetone (DHA) after they were hydrolysed by ALP, which reacts with lucigenin and produces strong chemiluminescence. Under the optimum assay condition, the detection limits were 3.8 × 10^?19 and 1.5 × 10^?18 moles of ALP, respectively. The coefficients of variation (CV) at each points on the standard curve were 0.8–5.4% and 1.8–7.1% (n = 6), respectively. The mechanism of lucigenin CL with DHA was investigated by ESR spectrometry using the spin‐trapping method. The mechanism was speculated as follows: the O₂^? generated by the reaction of DHA and O₂ in alkaline solution reacts with lucigenin, and then emit light. The proposed CL assay was applied to the enzyme immunoassay of 17β‐oestradiol, using ALP as a label enzyme. The measurable range of 17β‐oestradiol was 15–4000 pg/mL, and the proposed method was four times more sensitive than the colorimetric assay for ALP by using 4‐nitrophenyl phosphate as substrate. Copyright © 2002 John Wiley & Sons, Ltd.     

The determination of glutamine with flow‐injection chemiluminescence detection and mechanism study

The main purpose of this study was to develop an inexpensive, simple, rapid and sensitive chemiluminescence (CL) method for the determination of glutamine (Gln) using a flow‐injection (FI) system. Gln was found to strongly inhibit the CL signal of the luminol–H₂O₂–CuSO₄ system in Na₂B₄O₇ solution. A new FI‐CL method was developed for the determination of Gln. Parameters affecting the reproducibility and CL detection were optimized systematically. Under the optimized conditions, the corresponding linear regression equation was established over the range of 5.0 × 10^?7 to 2.5 × 10^?6 mol/L with the detection limit of 1.8 × 10^?8 mol/L. The relative standard deviation was found to be 1.8% for 11 replicate determinations of 1.5 × 10^?6 mol/L Gln. The proposed method has been satisfactorily applied for the determination of Gln in real samples (Marzulene‐s granules) with recoveries in the range of 98.7–108.6%. The minimum sampling rate was about 100 samples/h. The possible mechanism of this inhibitory CL was studied by fluorescence spectrophotometer and UV–vis spectrophotometer. Copyright © 2009 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescence of the luminol–potassium periodate system enhanced by TGA–capped CdTe quantum dots for the determination of theophylline

The chemiluminescence (CL) behaviour of the luminol–potassium periodate system enhanced by CdTe quantum dots capped with thioglycolic acid (TGA–CdTe QDs) was studied using kinetic experiments, CL spectra, UV–vis absorption spectra and fluorescence spectra. The production of oxygen‐containing reactant intermediates (O₂^?? and OH^?) in the present CL system was verified by CL. The possible CL mechanism was discussed in detail. Furthermore, theophylline (THP) was determined based on its enhancement of the CL intensity of the CdTe QDs–luminol–potassium periodate system coupled with a flow‐injection technique. Under these optimized conditions, the linear range was found to be from 1.0 × 10^?8 to 1.0 × 10^?5 g/mL with a detection limit of 2.8 × 10^?9 g/mL (3σ). The recoveries for the determination of THP in tablets were from 98.2 to 99.6%.     

A flow injection chemiluminescence method for the determination of lincomycin in serum using a diperiodato-cuprate (III)-luminol system

In this paper, the novel trivalent copper–periodate complex {K₅[Cu(HIO₆)₂], DPC} has been applied in a luminol‐based chemiluminescence (CL) reaction. Coupled with flow injection (FI) technology, the FI‐CL method was proposed for the determination of lincomycin hydrochloride. The CL reaction between luminol and DPC occurred in an alkaline medium. The CL intensity could be greatly enhanced by lincomycin hydrochloride. The relative CL intensity was proportional to the concentration of lincomycin hydrochloride in the range of 1 × 10^?8 to 5 × 10^?6 g mL^?1 and the detection limit was at the 3.5 × 10^?9 g mL^?1 level. The relative standard deviation at 5 × 10^?8 g mL^?1 was 1.7% (n = 9). The sensitive method was successfully applied to the direct determination of lincomycin hydrochloride (ng mL^?1) in serum. A possible mechanism of the lumonol–DPC CL reaction was discussed by the study of the CL kinetic characteristics and the spectra of CL reaction. The oxidability of DPC was studied by means of its electrochemical response. Copyright © 2010 John Wiley & Sons, Ltd.     

Development of an enhanced chemiluminescence immunoassay (CLIA) for detecting urinary albumin

In the present study, a sensitive and competitive chemiluminescence immunoassay (CLIA) was developed in order to detect human serum albumin (HSA) in urine specimen. The method utilizes a home-made monoclonal anti-albumin antibody conjugated to horseradish peroxidase enzyme (mAb-HRP). Sensitivity, specificity and linearity of the assay were evaluated. According to the results, the proper concentration of HSA and mAb-HRP conjugates was 800?ng/100?μl and 1:200 respectively. In optimal conditions, this method could detect HSA in a high linear range of 10–200?μg?ml^?1 with the low detection limit of 0.025?μg?ml^?1. No evidence of interference with presence of probable substances in the urine samples indicated its high specificity and selectivity. Moreover, high reproducibility as well as high sensitivity and specificity of the test were confirmed using diabetic and non-diabetic samples. Significant concordance was observed between CLIA and immunoturbidimetry assay regarding detection of HSA. The results of the present study can be considered in accordance with the current demands such as reliability, accuracy, convenience and high speed of performance for a precise protein detection method. Furthermore, it may be regarded as a more rapid, simpler and cheaper alternative compared to other sophisticated assays.     

Sensitive determination of epinephrine in pharmaceutical preparation by flow injection coupled with chemiluminescence detection and mechanism study

A novel, rapid and sensitive method was described for the determination of epinephrine (EP) using flow injection analysis coupled with chemiluminescence (CL) detection, which based on EP enhanced the weak CL emission of luminol–KIO₄ system in NaOH solution. Parameters affecting the CL intensity and reproducibility were optimized systematically. Under the optimized experiment conditions, the net CL intensity was proportional to the concentration of EP in the range of 5.0 × 10^?8 to 1.5 × 10^?6 mol/L with a detection limit of 1.9 × 10^?9 mol/L. The relative standard deviation (RSD) was found to be 0.7% for 13 replicate determinations of 3.0 × 10^?7 mol/L EP. The applicability of the proposed method was illustrated in the determination of EP in pharmaceutical preparation. The recoveries of EP at different levels in EP hydrochloride injection were between 95.4 and 104.7%. One assay procedure takes only 27 s, and the sampling rate was calculated about to be 130 samples/h. The possible mechanism of the enhanced CL intensity was studied by examining CL spectra and UV–vis spectra. Copyright © 2009 John Wiley & Sons, Ltd.