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.     

Synthesis and characterizations of iso‐luminol‐functionalized,tadpole‐shaped,gold nanomaterials

Iso‐luminol functionalized gold nanomaterials were synthesized in high yield by a simple seeding approach, using the chemiluminescent reagent iso‐luminol as reductant in the presence of HAuCl₄, AgNO₃ and cetyltrimethylammonium bromide (CTAB). The morphology of as‐prepared gold nanoparticles was characterized by transmission electron microscopy and UV–vis spectroscopy, showing that gold nanotadpoles (AuNTps) were obtained. Subsequent experiments revealed that the amounts of seed colloids and AgNO₃ and the concentrations of iso‐luminol and CTAB in the growth solution play critical roles in the formation of well‐shaped AuNTps. The surface state of AuNTps was characterized by UV–vis spectroscopy and fluorescence spectroscopy, indicating that iso‐luminol and its oxidation product, 4‐aminophthalate, coexisted on the surface of AuNTps. The CL behaviour was studied by static injection CL experiments, demonstrating that AuNTps were of CL activity. Finally, the growth mechanism of AuNTps was also discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Sensitive and selective determination of fluvoxamine maleate using a sensitive chemiluminescence system based on the alkaline permanganate–Rhodamine B–gold nanoparticles reaction

A high‐yield chemiluminescence (CL) system based on the alkaline permanganate–Rhodamine B reaction was developed for the sensitive determination of fluvoxamine maleate (Flu). Rhodamine B is oxidized by alkaline KMnO₄ and a weak CL emission is produced. It was demonstrated that gold nanoparticles greatly enhance this CL emission due to their interaction with Rhodamine B molecules. It is also observed that sodium dodecyl sulfate, an anionic surfactant, can strongly increase this enhancement. In addition, it was demonstrated that a notable decrease in the CL intensity is observed in the presence of Flu. This may be related to Flu oxidation with KMnO₄. There is a linear relationship between the decrease in CL intensity and the Flu concentration over a range of 2–300 µg/L. A new simple, rapid and sensitive CL method was developed for the determination of Flu with a detection limit (3s) of 1.35 µg/L. The proposed method was used for the determination of Flu in pharmaceutical and urine samples. Copyright © 2014 John Wiley & Sons, Ltd.     

Chemiluminescence flow biosensor for glucose based on gold nanoparticle-enhanced activities of glucose oxidase and horseradish peroxidase

In this work, a novel chemiluminescence (CL) flow biosensor for glucose was proposed. Glucose oxidase (GOD), horseradish peroxidase (HRP) and gold nanoparticles were immobilized with sol-gel method on the inside surface of the CL flow cell. The CL detection involved enzymatic oxidation of glucose to d-gluconic acid and H(2)O(2), and then the generated H(2)O(2) oxidizing luminol to produce CL emission in the presence of HRP. It was found that gold nanoparticles could remarkably enhance the CL respond of the glucose biosensor. The enhanced effect was closely related to the sizes of gold colloids, and the smaller the size of gold colloids had the higher CL respond. The immobilization condition and the CL condition were studied in detail. The CL emission intensity was linear with glucose concentration in the range of 1.0 x 10(-5)molL(-1) to 1.0 x 10(-3)molL(-1), and the detection limit was 5 x 10(-6)molL(-1) (3sigma). The apparent Michaelis-Menten constant of GOD in gold nanoparticles/sol-gel matrix was evaluated to be 0.3mmolL(-1), which was smaller than that of GOD immobilized in sol-gel matrix without gold nanoparticles. The proposed biosensor exhibited short response time, easy operation, low cost and simple assembly, and the proposed biosensor was successfully applied to the determination of glucose in human serum.     

Potassium permanganate–glutaraldehyde chemiluminescence system catalyzed by gold nanoprisms toward selective determination of fluoride

Gold and silver nanoparticles (NPs) are shown to exert a positive effect on the chemiluminescence (CL) reaction of permanganate aldehydes. Interestingly, between various shapes examined, Au nanoprisms have the highest beneficial effect. This effect is even more notable in the presence of sodium dodecyl sulfate (SDS) surfactant. UV‐vis spectra and transmission electron microscopy were used to characterize the NP shapes and sizes. Furthermore, it was observed that iron(III) ions can slightly increase CL emission of this system. This intensification is very effective in the presence of fluoride ions (F^–). These observations form the basis of the method for the high sensitive determination of F^– in the 6–1200 nmol L^–1 concentration range, with a detection limit of 2.1 nmol L^–1. The proposed method has good precision and was satisfactorily used in the selective determination of low concentrations of fluoride ion in real samples. Copyright © 2015 John Wiley & Sons, Ltd.     

Chemiluminescence of off‐line and on‐line gold nanoparticle‐catalyzed luminol system in the presence of flavonoid

It was found that flavonoids could remarkably inhibit the chemiluminescence (CL) intensity of an off‐line gold nanoparticle (AuNP)‐catalyzed luminol–H₂O₂ CL system. By contrast, flavonoids enhanced the CL intensity of an on‐line AuNP‐catalyzed luminol–H₂O₂ CL system. In the off‐line system, the AuNPs were prepared beforehand, whereas in the on‐line system, AuNPs were produced by on‐line mixing of luminol prepared in a buffer solution of NaHCO₃ ? Na₂CO₃ and HAuCl₄ with no need for the preliminary preparation of AuNPs. The on‐line system had prominent advantages over the off‐line system, namely a lowering of the background noise and improvements in the stability of the CL system. The results show that differences in the signal suppression effect of flavonoids on the off‐line AuNP‐catalyzed CL system are influenced by the combined action of a free radical scavenging effect and occupy‐sites function; the latter was proved to be predominant using controlled experiments. Enhancement of the on‐line system was ascribed to the presence of flavonoids promoting the on‐line formation of AuNPs, which better catalyzed the luminol–H₂O₂ CL reaction, and the enhancement activity of the six flavonoids increased with the increase in reducibility. This work broadens the scope of practical applications of an AuNP‐catalyzed CL system.     

Flow injection chemiluminescence determination of lercanidipine based on N‐chlorosuccinimide–eosin Y post‐chemiluminescence reaction

A novel post‐chemiluminescence (PCL) reaction was discovered when lercanidipine was injected into the CL reaction mixture of N‐chlorosuccinimide with alkaline eosin Y in the presence of cetyltrimethylammonium bromide (CTAB), where eosin Y was used as the CL reagent and CTAB as the surfactant. Based on this observation, a simple and highly sensitive PCL method combined with a flow injection (FI) technique was developed for the assay of lercanidipine. Under optimum conditions, the CL signal was linearly related to the concentration of lercanidipine in the range 7.0 × 10^‐10 to 3.0 × 10^‐6 g/mL with a detection limit of 2.3 × 10^‐10 g/mL (3σ). The relative standard deviation (RSD) was 2.1% for 1.0 × 10^‐8 g/mL lercanidipine (n = 13). The proposed method had been applied to the estimation of lercanidipine in tablets and human serum samples with satisfactory results. The possible CL mechanism is also discussed briefly. Copyright © 2014 John Wiley & Sons, Ltd.     

A validated silver‐nanoparticle‐enhanced chemiluminescence method for the determination of citalopram in pharmaceutical preparations and human plasma

A simple and sensitive chemiluminescence (CL) method was developed for the determination of citalopram in pharmaceutical preparations and human plasma. The method is based on the enhancement of the weak CL signal of the luminol–H₂O₂ system. It was found that the CL signal arising from the reaction between alkaline luminol and H₂O₂ was greatly increased by the addition of silver nanoparticles in the presence of citalopram. Prepared silver nanoparticles (AgNPs) were characterized by UV–visible spectroscopy and transmission electron microscopy (TEM). Various experimental parameters affecting CL intensity were studied and optimized for the determination of citalopram. Under optimized experimental conditions, CL intensity was found to be proportional to the concentration of citalopram in the range 40–2500 ng/mL, with a correlation coefficient of 0.9997. The limit of detection (LOD) and limit of quantification (LOQ) of the devised method were 3.78 and 12.62 ng/mL, respectively. Furthermore, the developed method was found to have excellent reproducibility with a relative standard deviation (RSD) of 3.65% (n = 7). Potential interference by common excipients was also studied. The method was validated statistically using recovery studies and was successfully applied to the determination of citalopram in the pure form, in pharmaceutical preparations and in spiked human plasma samples. Percentage recoveries were found to range from 97.71 to 101.99% for the pure form, from 97.84 to 102.78% for pharmaceutical preparations and from 95.65 to 100.35% for spiked human plasma. Copyright © 2013 John Wiley & Sons, Ltd.     

Study of the enhancement of a new chemiluminescence reaction and its application to determination of β‐lactam antibiotics

An enhanced thiosemicarbazide(TSC)–H₂O₂ chemiluminescence (CL) system was established and proposed as a new analytical method for determination of β‐lactam antibiotics, ampicillin sodium and amoxicillin at microgram levels. The method is based on the inhibition of CL emission accompanying oxidation of TSC by H₂O₂ in alkaline medium. The effect of anionic, cationic, and non‐ionic surfactants on the CL emission of the system was studied. Both N‐cetyl‐N,N,N‐trimethylammonium bromide (CTMAB) and Triton X‐100, unlike sodium dodecyl sulfate (SDS), reinforced the CL intensity and were efficient to approximately the same level. The effect of the presence of eight non‐aqueous solvents on the CL system was also investigated. Upon addition of both of the non‐ionic surfactant, Triton X‐100, and the non‐aqueous solvent, N,N‐dimethyl formamide (DMF), the intensity of the CL reaction was increased 100‐fold. This method allows the measurement of 25–545 µg amoxicillin, and 35–350 µg ampicillin sodium. The detection limits are 8 µg for amoxicillin and 9 µg for ampicillin sodium. The relative standard deviations of six replicate measurements of 200 µg amoxicillin and 200 µg ampicillin sodium were 1.9 and 2.1%, respectively. The effect of foreign species on the determination of amoxicillin and ampicillin sodium was also examined. The proposed method was successfully applied to the determination of ampicillin sodium and amoxicillin in some pharmaceutical dosage forms. Copyright © 2008 John Wiley & Sons, Ltd.     

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.     

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.     

Design of five‐layer gold nanoparticles self‐assembled in a liquid open tubular column for ultrasensitive nano‐LC‐MS/MS proteomic analysis of 80 living cells

In this work, for the first time, a liquid open tubular column modified by five‐layer gold nanoparticles and linked with C₁₈ (GNPs@C₁₈) was designed and fabricated for nano‐LC‐MS/MS analysis of 80 living cells. Sixty nanometer gold nanoparticles were self‐assembled layer by layer on the inner wall of a 20 μm id fused‐silica capillary. C₁₈ was then linked on the gold nanoparticles to make the liquid open tubular column show hydrophobic character. Enough loading capacities for analysis of 80 living cells, ～100 fmol for pk‐10 and ～30 fmol for insulin, were obtained with the 2 m × 20 μm id five‐layer GNPs@C₁₈ open tubular column. The open tubular column was used in an online pretreatment and direct nano‐LC‐MS/MS analysis system to analyze 80 living HepG2 cells. In total, 650 proteins were identified in triplicate runs. The subcellular localization of the identified proteins showed that our system had no bias toward different cellular compartments. Protein copy number per cell of the identified proteins showed that the detection limit could reach 50 zmol and the abundance of the identified proteins could cover a dynamic range of 6 orders.     

Microbial synthesis of gold nanoparticles using the fungus <Emphasis Type="Italic">Penicillium brevicompactum</Emphasis> and their cytotoxic effects against mouse mayo blast cancer C<Subscript>2</Subscript>C<Subscript>12</Subscript> cells

Microorganisms, their cell filtrates, and live biomass have been utilized for synthesizing various gold nanoparticles. The shape, size, stability as well as the purity of the bio synthesized nanoparticles become very essential for application purpose. In the present study, gold nanoparticles have been synthesized from the supernatant, live cell filtrate, and biomass of the fungus Penicillium brevicompactum. The fungus has been grown in potato dextrose broth which is also found to synthesize gold nanoparticles. The size of the particles has been investigated by Bio-TEM before purification, following purification and after storing the particles for 3 months under refrigerated condition. Different characterization techniques like X-ray diffraction, Fourier transform infrared spectroscopy, and UV–visible spectroscopy have been used for analysis of the particles. The effect of reaction parameters such as pH and concentration of gold salt have also been monitored to optimize the morphology and dispersity of the synthesized gold nanoparticles. A pH range of 5 to 8 has favored the synthesis process whereas increasing concentration of gold salt (beyond 2 mM) has resulted in the formation of bigger sized and aggregated nanoparticles. Additionally, the cytotoxic nature of prepared nanoparticles has been analyzed using mouse mayo blast cancer C₂C₁₂ cells at different time intervals (24, 48, and 72 h) of incubation period. The cells are cultivated in Dulbecco’s modified Eagle’s medium supplemented with fetal bovine serum with antibiotics (streptopenicillin) at 37°C in a 5% humidified environment of CO₂. The medium has been replenished every other day, and the cells are subcultured after reaching the confluence. The viability of the cells is analyzed with 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide method.     

Mechanistic approach for fabrication of gold nanoparticles by Nitzschia diatom and their antibacterial activity

The problem of chemically synthesized nanoproducts motivated scientific community to explore ecofriendly methods of nanosynthesis. Diatoms belong to a group of aquatic, unicellular, photosynthetic microalgae have been scarcely investigated as a source of reducing and capping agents for nanosynthesis of pesticides and antibiotics. The present study reports a novel ecofriendly method for the fabrication of bioactive gold nanoparticles using locally isolated Nitzschia diatoms. The diatom-fabricated gold nanoparticles show characteristic ruby red colored with sharp absorbance peak at 529 nm. Electron microscopy confirmed irregular shape of gold nanoparticles, with average size of 43 nm and zeta potential of −16.8 mV. The effects of gold nanoparticles on diatom viability were investigated using light and electron microscopy. The mechanistic approach to shed light on how diatoms reacted after exposure to gold metal salt revealed that exposure to gold chloride triggers elevated levels of catalase and peroxidase (12.76 and 14.43 unit/mg protein, respectively) to relieve reactive oxygen species (ROS) stress induced by gold salt exposure. Investigation studies on mechanisms behind Nitzschia-mediated gold nanoparticles fabrication outlined the role of diatom proteins, polysaccharides in reduction, and stabilization of nanoparticles as confirmed by FT-IR analysis. Bioactivity of gold nanoparticles was accessed by coupling them with antibiotics (penicillin and streptomycin), which increased their antibacterial activity compared to individual nanoparticles and antibiotics (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus). Overall, the present novel phyco-nanotechnological approach is a promising tool to be used as sustainable strategy in green nanotechnology as well as to reduce use of antibiotics in microbial control.     

Chemiluminescence determination of gemifloxacin based on diperiodatoargentate (III)‐sulphuric acid reaction in a micellar medium

A novel flow‐injection chemiluminescence (FI‐CL) analysis method for the determination of gemifloxacin in the presence of cetyltrimethylammonium bromide (CTAB) surfactant micelles is described. Strong CL signal was generated during the reaction of gemifloxacin with diperiodatoargentate (III) in a sulfuric acid medium sensitized by CTAB. Under optimum experimental conditions, the CL intensity was linearly related to the concentration of gemifloxacin from 1.0 × 10^‐9 to 3.0 × 10^‐7 g/mL and the detection limit was 7.3 × 10^‐10 g/mL (3σ). The relative standard deviation (RSD) was 1.7 % for a 3.0 × 10^‐8 g/mL gemifloxacin solution (11 repeated measurements). The proposed method was successfully applied to the determination of gemifloxacin in pharmaceutical preparations and biological fluids. The possible mechanism of the CL reaction is also discussed briefly. Copyright © 2012 John Wiley & Sons, Ltd.     

Eco‐friendly synthesis of gelatin‐capped bimetallic Au–Ag nanoparticles for chemiluminescence detection of anticancer raloxifene hydrochloride

This study described the utility of green analytical chemistry in the synthesis of gelatin‐capped silver, gold and bimetallic gold–silver nanoparticles (NPs). The preparation of nanoparticles was based on the reaction of silver nitrate or chlorauric acid with a 1.0 wt% aqueous gelatin solution at 50°C. The gelatin‐capped silver, gold and bimetallic NPs were characterized using transmission electron microscopy, UV–vis, X‐ray diffraction and Fourier transform infrared spectroscopy, and were used to enhance a sensitive sequential injection chemiluminescence luminol–potassium ferricyanide system for determination of the anticancer drug raloxifene hydrochloride. The developed method is eco‐friendly and sensitive for chemiluminescence detection of the selected drug in its bulk powder, pharmaceutical injections and biosamples. After optimizing the conditions, a linear relationship in the range of 1.0 × 10^–9 to 1.0 × 10^–1 mol/L was obtained with a limit of detection of 5.0 × 10^–10 mol/L and a limit of quantification of 1.0 × 10^‐9 mol/L. Statistical treatment and method validation were performed based on ICH guidelines. Copyright © 2016 John Wiley & Sons, Ltd.     

A simple and sensitive flow injection chemiluminescence immunoassay for chloramphenicol based on gold nanoparticle‐loaded enzyme

A simple and ultrasensitive flow injection chemiluminescence competitive immunoassay based on gold nanoparticle‐loaded enzyme for the detection of chloramphenicol (CAP) residues in shrimp and honey has been developed. Due to their good biocompatibility and large specific surface area, carboxylic resin beads can be used as solid phase carriers to immobilize more coating antigens (Ag). In addition, gold nanoparticles could provide an effective matrix for loading more CAP antibody and horseradish peroxidase, which would effectively catalyze the system of luminol–p‐iodophenol (PIP)–H₂O₂. A competitive immunoassay strategy was used for detection of CAP, in which CAP in the sample would compete with the coating Ag for the limited antibodies, leading to a chemiluminescence (CL) signal decrease with increase in CAP concentration. A wide linear range 0.001–10 ng ml^?1 (R² = 0.9961) was obtained under optimized conditions, and the detection limit (3σ) was calculated to be 0.33 pg ml^?1. This method was also been successfully applied to determine CAP in shrimp and honey samples. The immunosensor proposed in this study not only has the advantages of high sensitivity, wider linear range, and satisfactory stability, but also expands the application of flow injection CL immunoassay in antibiotic detection.     

Chemiluminescence assay for kanamycin based on target recycling strategy

A chemiluminescence (CL) sensing strategy for kanamycin residue detection in fish samples was established based on luminol-functionalized gold nanoparticles as CL nanoprobe materials combined with DNA hairpin structure and carboxyl-modified magnetic beads. Relying on nucleic acid amplification technology, the system can successfully realize the recycling of kanamycin, so that the biosensor can release a large number of luminol-functionalized gold nanoparticles with excellent CL performance even at a low residual levels of kanamycin. The biosensor strategy showed a good linear relationship with kanamycin in the range 0.09–130 nM, the detection limit was as low as 0.04 nM. This method proves the excellent performance of the sensing strategy and provides a low-cost and high-sensitivity CL analysis strategy for the detection of kanamycin and even other antibiotics.     

A novel chemiluminescent flow‐injection analysis of transferrin by its reduction of the luminol—hydrogen peroxide reaction catalysed by meso‐tetra‐(3‐methoxyl‐4‐hydroxyl) phenyl manganese porphyrin

Based on the inhibition effect of transferrin (Tf) on the reaction of the luminol–hydrogen peroxide (H₂O₂) chemiluminescence (CL) system, catalysed by meso‐tetra‐(3‐methoxyl‐4‐hydroxyl) phenyl manganese porphyrin (MnP) as a mimetic enzyme of peroxides, a sensitive flow‐injection CL method has been developed for the determination of Tf in an alkaline medium. The CL reaction was carefully investigated by examining the variations of reaction conditions. Under optimum conditions, the linear range for the determination of transferrin was 0.04–20.0 μg/mL and the detection limit was 1.62 ng/mL. This proposed method was sensitive, convenient and simple, and has been successfully applied to the determination of transferrin in a serum sample. Copyright © 2011 John Wiley & Sons, Ltd.     

Investigation on the chemiluminescence reaction of the phenylhydrazine‐luminol–peroxide system

We studied the chemiluminescence (CL) oxidation of phenyl hydrazine–luminol with various organic and inorganic peroxides. Maximum CL intensity for this system was obtained for t‐butylhydroperoxide. The enhancement in CL depended strongly on pH and was greatest at pH 12.5. The solvent drastically enhanced the CL intensity. DMSO was found to increase the CL intensity many‐fold as compared to acetonitrile and water. The effect of temperature on CL intensity has also been studied. The CL spectra revealed a broad peak at 425 nm, which suggests excited 3‐aminophthalate ion as the luminophor. A mechanism to explain the reactions is suggested. Copyright © 2012 John Wiley & Sons, Ltd.