Improving Luminol Blood Detection in Forensics

Stoica, Bogdan A.; Bunescu, Sabina; Neamţu, Andrei; Bulgaru-Iliescu, Diana; Foia, Liliana; Botnariu, Eosefina Gina

doi:10.1111/1556-4029.13141

Cited by 20 publications

(19 citation statements)

References 27 publications

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“…This is particularly problematical, when the luminol reaction is used in forensic chemistry, and the data obtained are used as evidence before a court. 41−45 In such cases, several different methods 46 have to be applied to substantiate the result.…”

Section: Discussionmentioning

confidence: 99%

Redox Modulators Determine Luminol Luminescence Generated by Porphyrin-Coordinated Iron and May Repress “Suicide Inactivation”

Plieth

2018

ACS Omega

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Iron porphyrin catalysts of the luminol reaction (horseradish peroxidase, hemoglobin, cytochrome c , and hemin) interact with diverse reducing compounds. Here, it is demonstrated how the chemiluminescence yield is modulated by such interactions. The compounds accepted as substrates protect the catalyst against the “suicide inactivation” caused by high peroxide concentrations. The reducing agents not accepted by the catalyst inhibit light production either by generating a futile redox cycle of the luminophore or by irreversibly inactivating the catalytic center. In the case of a futile cycle, light emission resumes as soon as the reducing agents in the reaction are consumed, whereas with an irreversible inactivation, light emission does not recover. The characteristics of luminescence enhancement and quenching depending on interfering agents are also reported here. They reveal details about the relative redox potentials of the involved compounds. It is discussed how this should be considered when the luminol reaction is used for quantitative analyses and when unpurified samples with a broad compound matrix are to be assayed.

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Section: Discussionmentioning

confidence: 99%

Redox Modulators Determine Luminol Luminescence Generated by Porphyrin-Coordinated Iron and May Repress “Suicide Inactivation”

Plieth

2018

ACS Omega

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“…In particular, assays based on luminol, one of the most important chemiluminescent compounds, 1 are used for a broad variety of analytes (ref (2) and more refs in ref (3)), and even forensic investigators take advantage of the luminol-based detection of blood. 4 However, circumspection is necessary with assay design when the luminol reaction is employed, and the light yield (photon counts) is used to determine analyte concentrations. The systematic experimental survey reported here investigates the molecular causes of the so-called “suicide inactivation” and the changes in luminescence yield and kinetics linked with it.…”

Section: Introductionmentioning

confidence: 99%

Peroxide-Induced Liberation of Iron from Heme Switches Catalysis during Luminol Reaction and Causes Loss of Light and Heterodyning of Luminescence Kinetics

Plieth

2019

ACS Omega

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The peroxidation of luminol yields bright luminescence when the reaction is catalyzed by heme proteins. However, an excess of peroxide leads to less light and altered luminescence kinetics, an effect commonly referred to as “suicide inactivation”. The aim of this study is to present the molecular processes causing this effect. A comprehensive set of data reported here demonstrates that suicide inactivation is due to a peroxide-induced liberation of iron from its coordinating porphyrin. Liberated iron launches catalysis of the reaction at much lower efficiency. The light-yielding efficiencies of different organic and inorganic catalysts are precisely quantified and compared. It is shown that the catalysis by free iron involves superoxide. This is explained by the formation of a ferryl-oxo-iron complex. In this context, a complete reaction mechanism involving a modified Fenton–Haber–Weiss cycle is proposed for the first time. The switch from the highly efficient biogenically catalyzed luminescence to a less efficient inorganically catalyzed reaction is accompanied by a transition from “flash-type” to “glow-type” luminescence kinetics. Ethylenediaminetetraacetic acid-mediated chelation of iron is used to demonstrate this effect and to separate both kinetics. The explanation of kinetic heterodyning is underpinned by mathematical modeling. The results are able to explain the as yet unexplained phenomena discussed in the less recent literature and to settle disputes about them. It is concluded that peroxide concentrations exceeding the level tolerated by the catalyzing heme protein negatively impact performance and precision of luminol-based assays, where the light yield is used as a quantitative measure for analyte concentrations.

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“…The mechanism of hemoglobin (Hb) and its blood derivatives to enhance the oxidation of luminol in the presence of an alkaline solution, is based on the peroxidase-like activity of hemoglobin . However, studied have attempted to improve the reaction of luminol from Weber protocol (Weber, 1996) through the use of natural cyclodextrin and urea (Stoica et al, 2016;Maeztu et al, 2010). Stoica et al (2016) investigated the influence of 8 M urea pretreatment on the Weber protocol by molecular dynamic simulation and they observed significantly stronger chemiluminescence signal with almost no false-positive reaction.…”

Section: Resultsmentioning

confidence: 99%

In-SilicoInvestigation of Luminol, Its Analogues and Improved Mechanism of Chemiluminescence for Blood Identification Beyond Forensics

Fatoki

2020

Preprint

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This study aimed to discover chemiluminescent analogues of luminol, understand their molecular binding to hemoglobin of bloodstains in the household crime, and the mechanism of chemiluminescence. Similarity and clustering analyses of luminol analogues were conducted, and molecular docking was carried out on hemoglobin from Homo sapiens and other four domestic organism namely Gallus gallus, Drosophila melanogaster, Rattus norvegicus, and Canis familiaris. The results show that the order of overall binding score is D. melanogaster > H. sapiens > C. familiaris > R. norvegicus > G. gallus. Seven compounds namely ZINC16958228, ZINC17023010, ZINC19915427, ZINC34928954, ZINC19915369, ZINC19915444, and ZINC82294978, were found to be consistently stable in binding to diverse hemoglobin and possibly have chemiluminescence than luminol. The amino acid residues involved in the interaction of human hemoglobin with the 30 test compounds, show that His45, Lys61, Asn68, Val73, Met76, Pro77, Ala79, Ala82, Leu83, Pro95, Phe98, Lys99, Ser102,Ser133, Ala134, and Thr134 are significant in the mechanism of action of presumptive test compounds. The improved mechanism of chemiluminescent identification of blood hypothesized that nitrite interact with the Fe(II) heme, with the cleavage of a hydroxide ion and the formation of the nitrosonium cation in peroxidase reaction. It was proposed that degradation of rhombic heme complex to fluorescent products is possibly inhibited by nitric oxide from the test compound luminol. This study provides novel insight on the luminol and its actual mechanism for broader possible applications of luminol with careful development of new methodologies.

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Improving Luminol Blood Detection in Forensics

Cited by 20 publications

References 27 publications

Redox Modulators Determine Luminol Luminescence Generated by Porphyrin-Coordinated Iron and May Repress “Suicide Inactivation”

Redox Modulators Determine Luminol Luminescence Generated by Porphyrin-Coordinated Iron and May Repress “Suicide Inactivation”

Peroxide-Induced Liberation of Iron from Heme Switches Catalysis during Luminol Reaction and Causes Loss of Light and Heterodyning of Luminescence Kinetics

In-SilicoInvestigation of Luminol, Its Analogues and Improved Mechanism of Chemiluminescence for Blood Identification Beyond Forensics

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