The effect of pH on chemiluminescence of different probes exposed to superoxide and singlet oxygen generators

Abstract

The compromised optima for high intensity chemiluminescence (CL), using superoxide generators, were all above pH 9.0 for the CL probes luminol and lucigenin. With luminol the optima were at pH 9.0 and 9.4 for the generators KO2 and hypoxanthine/xanthine oxidase (HX/XO), respectively. Lucigenin, with the same generators, produced optima at pH 9.5 and 10.0, respectively. The probe methyl-Cypridina-luciferin analogue (MCLA) produced optima closer to neutral pH, which is preferred for physiological assessments. MCLA had optima at pH 6.0, 8.7 and 9.5 with KO2 and with HX/XO optima at pH 4.8, 6.0, 7.0 and 8.7. When CL was assessed at physiological pH, MCLA observed superoxide radicals with a sensitivity of 100- and 330-fold more than luminol or luicigenin respectively. For singlet oxygen, the sensitivity of MCLA at this pH was 45- and 5465-fold more than for the said probes respectively. H2O2 did not elicit CL between pH 4 and 9.5 with any of the probes and did not influence the production of superoxide or singlet oxygen when co-assessed. Therefore CL could only be obtained when enzymes were used as converters. The optima for the enzyme-conversion system horseradish peroxidase (HRP)/H2O2, and luminol, were at pH 8.0 and 9.2. Lucigenin and HRP/H2O2 also had a biphasic CL profile with optima at pH 7.4 and 9.6. MCLA and HRP/H2O2 had five optima, with the major ones at pH 6.1 and beyond 10. The optima for the myeloperoxidase/H2O system were at 8.6 and beyond 10.0 when luminol and 0.15 mol/L NaBr were used.

Metabolism of Benzoquinone by Yeast Cells and Oxidative Characteristics of Corresponding Hydroquinone: Application to Highly Sensitive Measurement of Yeast Cell Density by Using Benzoquinone and a Chemiluminescent Probe

“…There was hardly any chemiluminescence generated by the seven derivatives of 1,4-BQ itself or by the chemiluminescent probes themselves such as lucigenin and luminol. On the other hand, the background value was high when MCLA, which produced an optimum close to neutral pH, 13,16) without catalysis, 17) and luminol with K 3 [Fe(CN) 6 ] 13) were used under alkaline conditions (data not shown). TCPO with pyrene 18) resulted in hardly any chemiluminescence (data not shown).…”

“…Therefore, the combination of a chemiluminescent probe and the seven derivatives of 1,4-HQ was studied to enable the highly sensitive detection of HQ. Lucigenin 13,14) and luminol 13,15) were considered to be effective as chemiluminescent probes because they gave maximum intensity under alkaline conditions. The chemiluminescence intensity generated by the seven derivatives of 1,4-BQ itself was also measured as the background value.…”

Raw material enzymatic activity determination: A specific case for validation and comparison of analytical methods—The example of superoxide dismutase (SOD)

“…Since the discovery of SOD by McCord and Fridovich in 1969 [3], several direct and indirect methods for SOD activity measurement have been developed (e.g., absorbance [4][5][6][7], chemiluminescence [8,9], electron spin resonance spectroscopy [10]) Data comparison obtained by the use of different methods is very difficult due to the fact that even a slight variation in assay conditions leads to very different results [11]. Among enzymatic activity assay, an indirect method using nitro blue tetrazolium (NBT) is commonly used due to its convenience and ease of use [12].…”

Much Stronger Chemiluminescence of 9-Mesityl-10-methylacridinium Ion than Lucigenin at Neutral Conditions for Co2+ Detection

“…Chemiluminescence (CL) is a phenomenon of light emission as a result of chemical reactions. , Due to the advantages of short analysis time, high sensitivity, simple instrumentation, good stability, and high cost-effectiveness, it is widely used in food analysis, chemical sensors, immunoassays, and environmental monitoring. − Combined with the flow injection system (FIA), the CL reaction is more controllable and suitable for building automated systems. − Moreover, the majority of traditional CL systems like lucigenin/H 2 O 2 need strongly alkaline conditions. CL probes under neutral conditions like acridinium esters are expensive and complex to synthesize, and luciferin analogues of CL probes need an additional enzyme, which limits their application. , Hence, the development of new efficient CL systems capable of operating under neutral or weakly acidic conditions is very important.…”

“…CL probes under neutral conditions like acridinium esters are expensive and complex to synthesize, and luciferin analogues of CL probes need an additional enzyme, which limits their application. 13,14 Hence, the development of new efficient CL systems capable of operating under neutral or weakly acidic conditions is very important.…”