Gil Grisshom in Las Vegas then Horatio Caine in Miami and finally, Marc Taylor in New York. In the last decade the main protagonists of the television series Crime Scene Investigation (CSI) have used the latest techniques to solve all kinds of murders.
Undoubtedly, one of the most used, and we have seen in almost every chapter, has been the reaction of luminol to detect traces of blood at the scene of various crimes. However, this technique has a serious drawback that has just been remedied by a group of Spanish scientists.
But go back in time and were not the first to use CSI luminol in their research. Many years ago, Sir Arthur Ignatius Conan Doyle gave us the first clue, and it was neither more nor less than when the then almost unknown Sherlock Holmes met his dear Doctor Watson . On that day in 1881 the legendary detective seeking a chemist to help him solve one of his many cases. Sherlock Holmes needed to detect the presence of blood at the scene of a crime but did not know how.
In the first chapter of the novel series, when the Doctor Watson is taken to meet the detective as a potential roommate, finds him shouting “I found it! I found it! “Referring to the discovery of a chemical that reacts only in contact with hemoglobin and with any other substance.
But that is what he found? How had that substance? What reaction is that triggered?
Today criminal investigation used to detect the presence of blood in the crime scene known as luminol reaction, a derivative of phthalic acid greenish and slightly soluble.
Luminol is oxidized in the presence of hydrogen peroxide in alkaline medium, which may act as the reaction catalyst heme present in the hemoglobin of blood and leading to blue light. In other words, a mixture of luminol + + alkali oxidizing agent, when in contact with blood, emits light. And spraying a solution of luminol in a suspicious area occurs phenomenon in which light is produced throughout a chemical reaction) at the places where blood has been, even if it has been washed and not noticeable to naked eye.
However, as discussed above, this reaction has a great disadvantage. Although luminol reaction can detect about 1 L of blood in 1 L of solution, in some cases the sensitivity of the method decreases implying that extremely low amounts of blood are sometimes undetectable.
To solve this problem recently Spanish research group has demonstrated in the prestigious scientific journal ” Journal of Physical B “as luminol encapsulation within a certain type of molecules not only increases the stability of luminol, but significantly increases the sensitivity of technique, allowing the detection of even lower levels of blood. These molecules, which are part of the avatar of the blog, are known as cyclodextrins , cyclic oligosaccharides containing 6 to 12 glucose units. Structurally, the cyclodextrins are ring-shaped truncated cone with a hydrophilic outer surface and an inner cavity of hydrophobic character.
The most important property of cyclodextrins is their ability to include a wide variety of molecules, such as luminol, within its hydrophobic cavity, which can alter some of the properties of the encapsulated molecule among which is their solubility , absorption, bio availability, stability, chemical re activity, and in the case that concerns us, its luminescence. Thus, the encapsulation of various luminescent substances, such as luminol, causes an increase in luminance because this property is enhanced by loss of mobility of luminol to be encapsulated within cyclodextrins.
And all this in what is translated? Well, it’s very simple, if you pulverize the scene of a crime with a traditional solution luminol in the presence of cyclodextrins can observe blood concentrations three times less than if we use the classical method used in criminology.
In a few chapters we can see how the usual techniques of gas chromatography, spectroscopy, electrophoresis, liquid chromatography and fluorimetry, the CSI Gil Grisshom , Horatio Caine and Marc Taylor will have to add a new scientific technique … the molecular encapsulation .