Chemiluminescence Signal Intensity Research Articles

Chemiluminescence detection of kanamycin by DNA aptamer regulating peroxidase-like activity of Co3O4 nanoparticles.

Kanamycin (KAN) is widely used as a growth hormone analog and an antibacterial agent. However, abuse of this substance has resulted in the accumulation of excessive residue levels in foods of animal origin, which presents a significant risk to human health. A chemiluminescent aptasensor was constructed for the rapid quantitative detection of KAN by combining the properties of Co3O4 nanoparticles (Co3O4 NPs) nanozyme activity and DNA aptamer with high specificity. The DNA aptamer/Co3O4 NPs nanozyme regulated the chemiluminescence signal by exploiting the chemiluminescent properties of luminol oxidation by H2O2. Specific binding of KAN to the aptamer led to the formation of a steric hindrance block in the solution, which inhibited the activity of nanozyme and reduced signal intensity. The degree of signal reduction is related to the concentration of KAN. Under optimal conditions, there was good linearity between KAN concentration and chemiluminescence signal intensity in the range of 0.5-8.0 μΜ, with a detection limit of 0.26 μΜ. The detection system performed well in the presence of competing antibiotics and was virtually unaffected. The method was also suitable for the detection of KAN in milk samples with sample recoveries of 97.8%-99.1%. The chemiluminescence sensor has the advantages of low cost, specificity, and sensitivity, and does not require an external light source or modification of the nucleic acid aptamer which makes it a promising candidate for applications in the field of food detection.

Bimetallic CuFe Prussian blue analogue cubes enhanced luminol chemiluminesence and its application

In this paper, bimetallic CuFe Prussian blue analogue (CuFe PBA) was discovered to have oxidase-like activity. Luminol can be oxidized under alkaline conditions without adding other oxidants. The chemiluminescence (CL) intensity produced is more than 1000 times that of the original luminol-NaOH system. Thus, a novel luminol-NaOH-CuFe PBA CL sensor was constructed. The CL intensity of the system would drastically decrease with the addition of uric acid (UA), it served as the foundation for the creation of an enzyme-free CL sensor for the determination of UA. The CL signal intensity of the system showed a linear connection with the square of the UA concentration in the range of 0.25 to 0.45 mmol·L−1, and the limits of detection was 0.10 mmol·L−1. This system could be used to construct an efficient CL sensor for the detection of UA in human serum.

Experimental investigation of flame fluctuation reduction in distributed combustion

Analysis of dynamic combustor stability is essential for the development of practical devices that employ distributed reaction zones. The fluctuation of reaction zone (RZ) was studied to compare normal air combustion and distributed combustion at an equivalence ratio of 0.9 in a swirl-stabilized burner using methane fuel. Distributed combustion was fostered by diluting the inlet air stream with carbon dioxide that resulted in a gradual drop in the adiabatic flame temperature (Tad). High-speed broadband chemiluminescence at 3 kHz was used to study the global combustion dynamics. Vortex shedding observed along the shear layers influenced the oscillation of flame base in normal air combustion. However, relatively stable bases were observed in distributed combustion. Fast Fourier Transformation performed on RZ base fluctuation data supported the observations from chemiluminescence signatures. Proper orthogonal decomposition (POD) analysis indicated various vortex-shedding patterns as the dominant structures in conventional swirl flames. The power spectral density (PSD) of POD modes showed the rotational effect of RZ and weak von Karman vortex shedding to influence fluctuation in distributed combustion. The self-sustained flame oscillations in normal swirl flames were investigated from the acoustic and heat release fluctuation signals. Both acoustic and heat release fluctuations gradually reduced when approaching the distributed combustion. The PSD of these signals demonstrated a common peak at ~ 174 Hz (in normal swirl flames) with possible thermo-acoustic coupling. This peak was consistent with the peaks obtained from the base fluctuation and POD spectra. The peak gradually diminished when approaching the state of distributed combustion. A similar observation of gradually decreasing acoustic and heat release fluctuation was made with a constant Tad. However, the drop in chemiluminescence signal intensity with CO2 dilution was relatively low in case of constant Tad compared to the variable Tad case. The local and global Rayleigh index obtained for the variable Tad cases at different dilution levels showed positive values at O2 = 21 and 20%, which signified self-sustained instability. However, the distributed combustion possessed a negative Rayleigh index indicating dampening of instability. These results support the gradual decline of thermo-acoustic instability when approaching the distributed combustion condition.

Abstract 3180: Development of a fully automated immunoassay system for detection of serum NY-ESO-1 and XAGE1 antibodies as biomarkers predicting the clinical efficacy of anti-PD-1 therapy

Abstract Background: Programmed cell death-1 (PD-1) and PD-ligand1 (PD-L1) inhibitors have become standard therapies for advanced non-small-cell lung cancer (NSCLC) due to prolonged patient survival. However, extended survival with anti-PD-1/PD-L1 therapy is limited to a small subset of NSCLC patients. Therefore, predictive biomarkers are needed to determine which patients will benefit. Recently, we reported that serum antibodies (Abs) against NY-ESO-1 and/or XAGE1 cancer-testis antigens are useful biomarkers that predict the clinical efficacy of anti-PD-1 monotherapy for NSCLC. The serum Abs were measured with enzyme-linked immunosorbent assay (ELISA); however, the ELISA method has several technical limitations for clinical applications. To overcome limitations in Ab measurement, we have developed a fully automated immunoassay system (HISCLTM) using chemiluminescent magnetic immunoassay technology. HISCLTM is widely used in many clinical fields because it is superior to ELISA due to its rapid reaction (17 minutes), wide dynamic ranges, and high reproducibility. Patients and Methods: Sera of NSCLC patients were obtained before anti-PD-1 monotherapy (nivolumab or pembrolizumab) as a part of standard care. NY-ESO-1/XAGE1 serum Abs were measured by ELISA and HISCLTM and their clinical performance was evaluated. In HISCLTM system, serum Abs were captured by magnetic beads coated with antigens, and the antigen-Ab complex was incubated with anti-human IgG conjugated with alkaline phosphatase. The chemiluminescent intensity acquired was then used for analyses. Results: Twenty-eight NSCLC patients were selected as the initial cohort for this study. Half of the patients responded to anti-PD-1 monotherapy and the remaining half did not. There were strong correlations between HISCLTM chemiluminescence signal intensity and titers of NY-ESO-1 and XAGE1 serum Abs in ELISA (r>0.93 for both). Twelve of thirteen Ab-positive patients in HISCLTM responded to anti-PD-1 therapy, while only two of fifteen Ab-negatives did (92% vs. 13%, p<0.001). Notably, the signal intensities in HISCLTM correlated well with tumor reduction rates after anti-PD-1 therapy. Serum NY-ESO-1/XAGE1 Ab-positivity in HISCLTM predicted efficacy with an AUC of 0.898, resulting in a sensitivity of 86% and specificity of 93%. Conclusions: We have developed a rapid and highly reproducible immunoassay system for detecting the serum NY-ESO-1 and XAGE1 Abs as predictive biomarkers of clinical benefits with anti-PD-1 monotherapy in NSCLC. In the future, our system would be examined in large-scale clinical trials for various other cancers. Citation Format: Yumiko Sakai, Hirotaka Abo, Kanako Sakaeda, Yusuke Atarashi, Nobuyuki Ide, Takaaki Yamaoka, Koji Kurose, Kenta Noda, Toshiyuki Sato, Toru Oga, Mikio Oka. Development of a fully automated immunoassay system for detection of serum NY-ESO-1 and XAGE1 antibodies as biomarkers predicting the clinical efficacy of anti-PD-1 therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3180.

Flame structure and emission signature in distributed combustion

Colorless distributed combustion (CDC) combustion technology offers significant advantages of ultra-low pollutants emission, stable operation and improved pattern factor for high intensity stationary gas turbines applications. Detailed knowledge on distributed combustion behavior is required to further deploy this technology. This paper reports the evolution of swirl flame shape, flame expansion and pollutants emission characteristics using propane, methane, and 20% and 40% hydrogen enriched methane fuels. The entrainment of hot reactive gases was simulated by diluting the inlet air stream with inert nitrogen or carbon dioxide. OH* chemiluminescence signatures, captured at different dilution levels, manifested gradual reduction of flame luminosity when CDC was approached. Flame boundaries derived using image threshold technique helped to visualize the broadened reaction zone under CDC conditions, which had much reduced chemiluminescence signal intensity. The rms to mean OH* signal variation at different dilution levels were analyzed to detect the initiation of CDC. The higher flame lift-off observed with CO2 dilution was due to higher heat capacity of CO2, resulting in greater flame speed reduction. Flame expansion, evaluated from the area encompassed within the flame boundary at different dilution levels showed a power-law behavior with both the diluents. Expansion of 4 to 5 times of initial flame volumes was observed under CDC using CO2 and N2 dilution, respectively. Significant reduction of NO and CO emission achieved under CDC was due to reduction of overall flame temperature, hotspot mitigation, and widened reaction zone occupying large flame volume, which makes it favorable for many practical combustor applications.

Investigating the impact of metal ions and 3D printed droplet microfluidics chip geometry on the luminol‑potassium periodate chemiluminescence system for estimating total phenolic content in olive oil.

The impact of the chip design and the mixing mechanisms using six different 3D printed microfluidic chips were investigated. The study was conducted using novel 3D printed droplet based microfluidics. A multi-mixing approach was utilized to enhance the CL signal of the CL system under investigation. The approach is based on droplet formation, droplet mixing and droplets merging in the 3D printed microfluidic chip. A 154% higher CL signal intensity was obtained using this approach compared to the CL signal obtained using the serpentine chip commonly used for improving the mixing inside droplet microfluidics. This chip was exploited to study the role of three metal ions: Co2+, Mn2+ and Fe2+ on catalyzing the luminol‑potassium periodate chemiluminescence (CL) reaction with selected phenolic compounds in basic media was carefully investigated. Furthermore, the luminol‑potassium periodate-metal ions system was optimized for all metal ions using gallic acid as the reference standard. Despite the popularity of luminol systems in estimating antioxidant activity or total phenolic content (TPC), the results of this study revealed the necessity of careful and vigilant attention when applying it to complex matrices. The only metal ion that showed quenching behavior with all 20 of the tested phenolic compounds was Fe2+, while Co2+and Mn2+ showed both quenching and enhancement in the CL signal. The luminol‑potassium periodate-Fe2+ system was applied to estimate TPC in olive oil extracts.

A competitive aptamer chemiluminescence assay for ochratoxin A using a single silica photonic crystal microsphere

We designed a competitive aptamer chemiluminescence assay for ochratoxin A (OTA) on the surface of a single silica photonic crystal microsphere (SPCM) in cereal samples. The structural color of SPCMs is used to recognize and trace the microspheres during process of detection. Anti-aptamer was immobilized on the surface of SPCM. OTA and anti-aptamer competed to bind to aptamer when OTA and its aptamer (labeled by biotin at 5′end) were added in the system. The chemiluminescence signal was developed by the horseradish peroxidase (HRP), luminol and H2O2. The molecules on the single SPCM can produce enough chemiluminescence signal intensity for quantitative detection for OTA. The linear detection range for OTA was from 1 pg/mL to 1 ng/mL and recovery rates were 89%–95%, 81%–92% and 94%–105% in rice, wheat and corn, respectively. The results showed that the developed method for OTA using a single SPCM has a great application potential in cereal samples.

Enhancing the chemiluminescence intensity of a KMnO4 formaldehyde system for estimating the total phenolic content in honey samples using a novel nanodroplet mixing approach in a microfluidics platform

A novel mixing approach was utilized with a highly sensitive chemiluminescence (CL) method to determine the total phenolic content (TPC) in honey samples using an acidic potassium permanganate-formaldehyde system. The mixing approach was based on exploiting the mixing efficiency of nanodroplets generated in a microfluidic platform. Careful optimization of the instrument setup and various experimental conditions were employed to obtain excellent sensitivity. The mixing efficiency of the droplets was compared with the CL signal intensity obtained using the common serpentine chip design, with both approaches using at a total flow rate of 15μlmin-1 ; the results showed that the nanodroplets provided 600% higher CL signal intensity at this low flow rate. Using the optimum conditions, calibration equations, limits of detection (LOD) and limits of quantification (LOQ) for gallic acid (GA), caffeic acid (CA), kaempferol (KAM), quercetin (QRC) and catechin (CAT) were obtained. The LOD ranged from 6.2ppb for CA to 11.0ppb for QRC. Finally, the method was applied for the determination of TPC in several local and commercial honey samples.

Flow-injection chemiluminescence method for the determination of moxifloxacin in pharmaceutical tablets and human urine using silver nanoparticles sensitized calcein-KMnO4 system.

Silver nanoparticles have been synthesized and were utilized for the enhanced luminometric estimation of moxifloxacin antibiotic. During the experimental procedure, it was clearly found that the addition of silver nanoparticles intensifies the weak chemiluminescence signal intensity of calcein-KMnO4 system by several folds. It was also obvious that the intensity enhancement was linearly proportional to the moxifloxacin concentration and this phenomenon was further utilized for the quantitative determination of target analyte. Effects of the different chemical variables during the experiment were studied to achieve best chemiluminescence signal. Under the optimized experimental parameters, the linear calibration graph was established over the moxifloxacin concentration range of 6.0×10(-8)M to 2.5×10(-6)M with coefficient of correlation (r (2)) value 0.9998. The lower detection limit was found to be 5.6×10(-9)M. The percentage relative standard deviation calculated from five replicate chemiluminescence measurements was found to be 2.63%. The developed chemiluminescence technique was successfully applied to the determination of moxifloxacin in tablet formulation and spiked human urine sample.

A lab-on-a-chip device for analysis of amlodipine in biological fluids using peroxyoxalate chemiluminescence system.

A highly sensitive, rapid and economical method for the determination of amlodipine (AM) in biological fluids was developed using a peroxyoxalate chemiluminescence (CL) system in a lab-on-a-chip device. Peroxyoxalate-CL is an indirect type of CL that allows the detection of native fluorophores or compounds derivatized with fluorescent labels. Here, fluorescamine was reacted with AM, and the derivatization product was used in a bis-(2,4,6-trichlorophenyl)oxalate-CL system. Fluorescamine reacts selectively with aliphatic primary amine at neutral or basic pH. As most of the calcium channel blocker and many cardiovascular drugs do not contain primary amine, the developed method is highly selective. The parameters that influenced the CL signal intensity were studied carefully. These included the chip geometry, pH, concentration of reagents used and flow rates. Moreover, we confirmed our previous observation about the effects of imidazole, which is commonly used in the bis-(2,4,6-trichlorophenyl)oxalate-CL system as a catalyst, and found that the signal was significantly improved when imidazole was absent. Under optimized conditions, a calibration curve was obtained with a linear range (10-100 µg/L). The limit of detection was 3 µg/L, while the limit of quantification was 10 µg/L. Finally the method was applied for the determination of AM in biological fluids successfully.

Chemiluminescence analysis of enrofloxacin in surface water using the tris(1,10-phenantroline)–ruthenium(II)/peroxydisulphate system and extraction with molecularly imprinted polymers

This paper reports a sensitive, highly selective flow injection (FI) method for the chemiluminescence-based determination of enrofloxacin (ENRO), a fluoroquinolone (FQ) antibiotic, in natural water samples. The detection principle is the on-line monitored photoreaction of tris(1,10-phenantroline)ruthenium(II) [Ru(phen) 3 2 + ] with peroxydisulphate ion to give Ru(phen) 3 3 + , which is then reduced by the antimicrobial producing the chemiluminescence (CL) signal. The low selectivity of the CL reaction required using solid-phase extraction with molecularly imprinted polymers (MISPE) in combination with the FI-CL system. Fluoroquinolone-selective MIP beads were obtained by acid etching of silica/MIP composites and packed into SPE cartridges to clean-up and preconcentrate samples prior injection into the FI-CL system. Various parameters influencing the CL signal intensity including pH, flow rate, and Ru(phen) 3 2 + and peroxydisulphate concentrations, were optimized. The variables affecting the extraction efficiency of the polymers were also optimized in order to minimize non-specific interactions and enable the selective uptake of the antibiotics from real samples. CL measurements made over the pH range 3.8–4.2 allowed the selective determination of enrofloxacin, and measurements at pH 4.8–5.8 the quantitation of total FQs (enrofloxacin, ciprofloxacin, norfloxacin, sarafloxacin, lomefloxacin and danofloxacin). The limit of detection for enrofloxacin was 0.27 μg L − 1 when 10 mL water samples were preconcentrates. The proposed method was used to determine trace amounts of FQs in mineral and tap water, and also in water samples from the river Quibú (Cuba), all with good recoveries: 84–119% (RSD 2.1–9.3%, n = 3) for samples fortified with enrofloxacin at concentrations from 4 to 40 μg L − 1 . The method was validated by HPLC with fluorescence detection. • A novel MISPE-FI-CL method for enrofloxacin analysis was developed using the Ru(phen) 3 2 + /S 2 O 8 2 − system. • Adequate selection of the carrier pH allows selective determination of enrofloxacin or fluoroquinolones screening • Other amine containing compounds present in natural water samples did not interfere. • The method was validated by HPLC-FLD and applied to tap and river water analysis.

Towards an ideal method for analysis of lisinopril in pharmaceutical formulations using a tris(2,2′-bipyridyl)-ruthenium(ii)-peroxydisulfate chemiluminescence system in a two chip device

A novel, rapid, selective and sensitive method has been developed for analysis of lisinopril (LIS) in pharmaceutical formulations using a tris(2,2′-bipyridyl)-ruthenium(II) (Ru(bipy)32+) peroxydisulfate chemiluminescence (CL) system in a two chip device. The parameters that influence the CL signal intensity were carefully optimized. These include pH, flow rates and concentration of reagents used. Under optimum conditions, a linear calibration curve between 0.25 and 50.0 μg mL−1 was obtained. About 180 samples were analyzed per hour while the detection limit was found to be 0.067 μg mL−1. The method was applied for analysis of LIS in pharmaceutical products and was found to be free from interferences of acid-induced degradation (AID) products and other ingredients usually present in these preparations.

Direct monitoring changes of salbutamol concentration in serum by chemiluminescent imaging

We report in this manuscript, the use of direct ammonium persulfate-enhanced chemiluminescence (CL) imaging, to monitor changes to measure serum salbutamol concentration in subjects of different haptoglobin (Hp) phenotypes at different dosing time. It was noted that CL generated from Hp was decreased due to salbutamol's reducibility, which was used for monitoring salbutamol concentration in serum. The serum from the subjects treated by oral administration of salbutamol, was collected at different dosing time and was separated by polyacrylamide gel electrophoresis (PAGE) prior to the CL detection. According to CL images, samples were separated into three groups based on the Hp phenotypes. The curves of CL signal intensity versus time were obtained for each group, and we demonstrated that there were more significant variables on binding ability between groups. The maximum salbutamol concentration in the serum appeared after 4 h, which was in agreement with the literature. In addition, the binding constants of salbutamol to Hp were determined by a fluorescence-based method, whose results were in agreement with the phenomenon of the greater salbutamol metabolism rate for Group Hp 1-1 than Group Hp 2-2. The presented method can monitor changes of salbutamol concentration in serum directly, making the procedures much simple, convenient, rapid and has the property of lower cost. It provided us with excellent reference information for the individual dosage regimen of different Hp groups, which hopefully could become a potential method for further pharmaceutical research.

Analysis of fexofenadine in pharmaceutical formulations using tris(1,10‐phenanthroline)–ruthenium(II) peroxydisulphate chemiluminescence system in a multichip device

A simple, rapid and sensitive method has been developed for the analysis of fexofenadine (FEX) in pharmaceutical formulations, using a tris(1,10-phenanthroline)-ruthenium(II) [Ru(phen)(3)(2+)] peroxydisulphate chemiluminescence (CL) system in a multichip device. Various parameters that influence the CL signal intensity were optimized. These included pH, flow rates and concentration of reagents used. Under optimum conditions, a linear calibration curve in the range 0.05-5.0 µg/mL was obtained. The detection limit was found to be 0.001 µg/mL. The procedure was applied to the analysis of FEX in pharmaceutical products and was found to be free from interference from concomitants usually present in these preparations.

High throughput method for the analysis of cetrizine hydrochloride in pharmaceutical formulations and in biological fluids using a tris(2,2′-bipyridyl)ruthenium(II)–peroxydisulphate chemiluminescence system in a two-chip device

A fast, economic and sensitive chemiluminescence (CL) method has been developed for the analysis of cetrizine hydrochloride (CET) in pharmaceutical formulations and in biological fluids. The CL method is based on the oxidation of tris(2,2′-bipyridyl)ruthenium(II) (Ru (bipy) 3 2+) by peroxydisulphate in a two-chip device. Up to 180 samples can be analysed per hour, consuming only minute quantities of reagents. Three instrumental setups were tested to find the most economical, sensitive and high throughput setup. In the first setup, a continuous flow of sample and CL reagents was used, whereas in the second setup, a fixed volume (2 μL) of (Ru (bipy) 3 2+) was introduced into a continuous infusion of peroxydisulphate and the sample. In the third design, a fixed volume of sample (2 μL) was injected while the CL reagents were continuously infused. Compared to the first setup, a 200% signal enhancement was observed in the third setup. Various parameters that influence the CL signal intensity, including pH, flow rates and reagent concentrations, were optimized. A linear response was observed over the range of 50 μg L −1 to 6400 μg L −1 ( R 2 = 0.9959) with RSD values of 1.1% ( n = 15) for 1000 μg L −1. The detection limit was found to be 15 μg L −1 (S/N = 3). The amount of consumed sample was only 2 μL, from which the detected amount of CET was found to be 6.5 × 10 −14 mol. This procedure was successfully applied to the analysis of CET in pharmaceutical formulations and biological fluids.

Formation of G-quadruplex-hemin DNAzyme based on human telomere elongation and its application in telomerase activity detection

In the present study, a chemiluminescence method for sensitive detection of human telomerase activity was developed based on the formation of G-quadruplex-hemin DNAzyme. In the presence of telomerase, the telomerase substrate (TS) primer elongated and a long single-strand DNA containing the telomere repeat units (TTAGGG)n was formed. When K + was introduced, the telomere repeat units could form G-quadruplex and then combined with hemin to form DNAzymes which could stimulate the generation of chemiluminescence (CL) in the presence of luminol and H 2O 2. The amount of telomerase elongation product was controlled by the content of telomerase extracted from HeLa cells, so the amount of DNAzymes and the intensity of chemiluminescence signal were all related to the number of HeLa cells. Using this simple method, the telomerase activity extracted from 100 cultured cancer cells could be detected without the polymerase chain reaction (PCR) amplification of telomerase elongated product.

Analysis of phenylephrine hydrochloride in pharmaceutical formulations and biological fluids using (2,2′-bipyridyl)ruthenium(ii)-peroxydisulphate chemiluminescence system in a two-chip microdevice

A two-chip microdevice has been developed for the analysis of phenylephrine hydrochloride (PEH) in pharmaceutical formulations and biological fluids using (2,2′-bipyridyl)ruthenium(II) (Ru(bipy)32+)-peroxydisulphate chemiluminescence (CL) system. It was observed that a pre-derivatization step is required to obtain an analytically useful CL signal. Using 0.5 mol L−1 formaldehyde solution as derivatization reagent, eighteen-time enhancement in the CL signal was observed. The derivatization reaction, photoreaction of (Ru(bipy)32+) with peroxydisulphate to produce (Ru(bipy)33+), reaction of (Ru(bipy)33+) with the derivatization product and detection of the produced CL signal were all carried out in this two-chip microdevice using minute quantity of reagents (27 μL per run). Various parameters that influence the derivatization reaction and the CL signal intensity were optimized. These include pH, flow rates and concentration of reagents used. A linear response was observed over the range 0.25 μg mL−1 to 15.0 μg mL−1 (R2 = 0.9999) with RSD values of 0.03% (n = 15) for 1 μg mL−1. The limit of detection (LOD) was found to be 0.027 μg mL−1 (S/N = 3). The developed method was successfully applied for the analysis of PEH in biological fluids and pharmaceutical formulations.

Enhancement of on chip chemiluminescence signal intensity of tris(1,10-phenanthroline)-ruthenium(II) peroxydisulphate system for analysis of chlorpheniramine maleate in pharmaceutical formulations

The effect of detection chip geometry on chemiluminescence (CL) signal intensity of tris(1,10-phenanthroline)-ruthenium(II) peroxydisulphate system for analysis of chlorpheniramine maleate (CPM) in pharmaceutical formulations was investigated. It was observed that the design of the detection chip is very crucial and can play an important role in enhancing the CL signal intensity in this system. The CL signal intensity was enhanced 250% when a teardrop micromixer chip was used, compared to the commonly used serpentine chip geometry. The study was conducted using a multi-chip device. In this device, chip 1 was used to prepare and pump the reagent mixture, whereas chip 3 was used for pumping the sample. The two chips were connected to the teardrop chip (2) via silica capillary where detection took place. Non-linear regression curve fitting of the calibration data revealed that the calibration curves are best described by third order polynomial equation with excellent correlation coefficients ( R 2 = 0.9998) for the concentration range 7.69 × 10 −8 to 5.12 × 10 −5 mol L −1. A linear response is also observed over the range 7.69 × 10 −8 to 1.28 × 10 −5 mol L −1 ( R 2 = 0.9996) and the detection limit was found to be 5.49 × 10 −8 mol L −1. The device was successfully used for the analysis of CPM in tablets and a multi-component cough syrup. Results were reproducible with relative standard deviation (RSD) of 0.6–1.1%.

Correlation between acidic potassium permanganate chemiluminescence and in vitrocell culture assay: Physiologically meaningful antioxidant activity

There is great interest in the activity of antioxidant molecules, including polyphenols, from food and plant sources. Acidic potassium permanganate chemiluminescence signal intensity was shown to predict the ability of polyphenols to positively act on cellular redox state and attenuate oxidative stress in cultured skeletal muscle cells.

Flow injection chemiluminescence determination of isoniazid using luminol and silver nanoparticles

Abstract The effect of silver colloidal nanoparticles (AgNPs) on the luminol–isoniazid system was investigated. It was found that AgNPs could act as a nanocatalyst on the luminol–isoniazid system to generate chemiluminescence (CL). The CL emission spectrum of the luminol–isoniazid–AgNPs system showed a peak with a maximum at 425 nm. It was suggested that the luminophor species was the excited state 3-aminophthalate. The reduction of dissolved O 2 to H 2 O 2 by isoniazid and decomposition of H 2 O 2 to the oxygen-related radicals were attributed to the catalytic effect of AgNPs. Under optimized conditions, the CL signal intensity was linear with the isoniazid concentration in the range of 10–1000 ng mL − 1 , with the correlation coefficient of 0.9996. The limit of detection was 2.7 ng mL − 1 isoniazid. The relative standard deviations for seven repeated measurements of 60 and 200 ng mL − 1 isoniazid were 1.4 and 2.4%, respectively. The effect of potent interfering compounds on the CL signal intensity of the proposed luminol–isoniazid–AgNPs system was investigated. The proposed method was successfully applied to the determination of isoniazid in a pharmaceutical sample.