Chemiluminescence Detection in the Study of Free-Radical Reactions. Part 2. Luminescent Additives That Increase the Chemiluminescence Quantum Yield

Quantification strategy of absolute chemiluminescence efficiency for systems of luminol with hydrogen peroxide

An important feature to be determined in mechanistic studies on chemiluminescence (CL) is its quantum efficiency, which can give significant chemical reaction information on the influence of the reactant structures and reaction conditions. However, most of the previous quantitative measurements of luminescence and quantum efficiencies are complex and incomplete. To overcome the inconvenience and underestimated quantum efficiency in each measurement, we report a simple and highly effective strategy to determine the absolute CL quantum efficiencies for three systems of luminol with hydrogen peroxide by means of a spectrometer along with an integrating sphere. The integrating sphere facilitated collection of all the emitted light and then transferred it to the spectrometer via an optical fiber proportionally. The CL quantum efficiency was determined by taking the ratio of total photons generated in the reaction system to the number of the limiting reactant molecules consumed. Absolute CL efficiencies of three luminol-H2O2 reaction systems with varied reactant concentrations or coreactants were found to be 37 %, 7.0 % and 6.6 % in a time course, which are much higher than those previously reported values of 1.0-1.3 %. Due to our complete photon collection design, a higher absolute CL efficiency can be realized. Furthermore, spooling CL spectra also provided a powerful visualization tool to observe the real-time CL evolution and devolution, allowing the study on kinetics of CL reaction systems. The above investigations are anticipated to promote further development of CL methodologies and their applications.

The use of a chemiluminescence in the assessment of the nanomaterials antioxidant activity

Nanomaterials are one of the most promising classes of advanced materials with fine-tuned biological activities. This is evidenced by the presence of redox activity of a number of nanoparticles aimed at inhibiting free radicals and/or mimicking the functions of enzymes. At the same time, it is impossible to study the expression of these biological properties without the use of well-standardized, representative techniques that provide availability, high precision, sensitivity, and selectivity of the measured characteristics. A method that satisfies these requirements is chemiluminescence analysis, which is widely used both in clinical analysis and to characterize the antioxidant activity of substances of natural or synthetic origin. Recently, a trend of using chemiluminescence analysis to study the biological activity of nanomaterials has appeared as a suitable alternative to spectroscopic and electrochemical techniques. This review briefly describes the examples of successful applications of chemiluminescence methods to study radical-binding and enzyme-like activities of nanomaterials. We discuss the data about the effect of the used reagents (radical-generating systems, chemiluminescence activators) and experimental conditions on the obtained values characterizing the nanomaterials activity.

Graphical Abstract

About work of a young member of the Radiobiological Society of the Russian Academy of Sciences

My name is Leonid Romodin. Within the framework of the VII Congress of Russian Biophysicists, I submitted an article devoted to the study of the penetration of chlorophyllin into cells from the intercellular medium. Chlorophyllin is a water-soluble saponification product of chlorophyll, which is the green pigment of plants. I became interested in chlorophyll because a number of researchers had reported on its radioprotective properties. However, all these data are fragmentary and not systematized. Therefore, it is necessary to conduct a comprehensive study of the radioprotective and other properties of chlorophyll and its derivatives. As a member of the Radiobiological Society of the Russian Academy of Sciences, I carry out research on the development of radioprotective drugs, including studies of chlorophyllin. In this commentary, I'd like to present my thoughts why biophysics can be considered the most important branch of biology, and here, I also introduce the reader in general terms to the research that I have conducted at different times.