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Laser Spectroscopy for Medicine

#3694


Applications of the Chemiluminescent Laser Spectroscopy for Diagnostics in Medicine and Biology

Tech Area / Field

  • MED-DID/Diagnostics & Devices/Medicine
  • BIO-RAD/Radiobiology/Biotechnology

Status
8 Project completed

Registration date
31.01.2007

Completion date
15.05.2012

Senior Project Manager
Malakhov Yu I

Leading Institute
Khlopin Radium Institute, Russia, St Petersburg

Supporting institutes

  • All-Russian Center of Emergency and Radiation Medicine named after A.M. Nikiforov, Russia, St Petersburg

Collaborators

  • Universität Ulm / Institut für Lasertechnologien in der Medizin und Messtechnik, Germany, Ulm\nHealth Protection Agency / Centre for Radiation, Chemical and Environmental Hazards, UK, Didcot

Project summary

Development of laser spectroscopy with tunable wavelength gives rise to new procedures for detection of trace amounts of various substances in various media.

The possibility of varying wavelength of laser radiation allows selective influence on atoms and molecules and, hence, their detection.

For a practical standpoint, liquids are the most suitable media for analysis since atoms and molecules in liquids are permanently located in the area of interaction with laser radiation. The laser spectroscopic methods allow determination of valence states and types of molecules.

The methods based on luminescence of atoms and molecules are the most sensitive in analysis of solutions. The limit of detection (LOD) determined without preconcentration is up to 10-13 M, in so doing, 1 ml of the solution is required for analysis. Thus, the LOD for a sample can reach 10-16 moles in 1 ml. To suppress background, the time-resolved (TR) technique based on a time delay of luminescence with respect to laser pulse is usually used. By now this procedure is used for detection of the following actinides in solutions.

Table 1. Limit of detection for TRLIF method

Element

UO2+

Cm3+

Am3+

Eu3+

Tb3+

Gd3+

Dy3+

Sm3+

Ce3+

Tm3+

LOD(M)

10-13

10-13

10-9

10-13

10-9

10-8

10-10

10-10

10-9

10-6

Unfortunately, Pu, Np, and some U compounds do not give direct luminescence in solutions and commonly adopted TR procedure with registration of luminescence cannot be used for their detection in solutions. We found that for detection of Pu, Np, and U the TR technique can be used with registration of chemiluminescence. We showed that in irradiation of solutions with laser radiation Pu, Np, and U induce chemiluminescence. During chemiluminescence, light emissive Luminol molecules are excited due to the energy released in chemical reaction. In our case, Luminol molecules emitted light due to interaction with excited molecules containing Pu, Np, or U. The use of laser radiation with tunable wavelength allows selective excitation of the certain sort of atoms, ions, or molecules. When actinide molecules are in the ground (not excited) state, the chemical reaction does not proceed. The chemical reaction is initiated only by excitation of actinide-containing molecules. Selection of wavelength of laser radiation allows excitation of the certain type of molecules of given actinide occurring in given valence state and detection of this actinide. In so doing, we can determine the valence state of actinide and molecule type. For registration the solution chemiluminescence is used.

Especially important fact is that we observed the delay of chemiluminescence with respect to laser pulse. This allows us to decrease significantly the background and to use highly sensitive methods of time-resolved laser spectroscopy.

We showed that detection of chemiluminescence with time resolution has LOD with respect to concentration from 10-11 to 10-13 M; in this case, 1 ml of the solution containing
10
-14-10-16 moles (6109-6107 atoms) of actinide is required for analysis.

For various actinides the LOD is:


Np, U, Pu: 10-13M – 2.4*10-14g/ml= 10-16mol/ml=6*107atoms/ml = 2.4*10-11g/l
237Np: 10-13M – 6.2*10-7Bq/ml = 6.2*10-4Bq/l
239Pu: 10-13M – 5.4*10-5Bq/ml = 5.4*10-2Bq/l
238U: 10-13M – 3*10-10Bq/ml = 3*10-7Bq/l
235U: 10-13M – 1.9*10-9Bq/ml = 1.9*10-6Bq/l
Thus, 239Pu can be detected without preconcentration at the level of 5.410-5 Bq in the sample added to the corresponding solution 1 ml in volume and, in so doing, data on valence state of Pu and the type of Pu-containing molecule can be obtained.

This proposal is aimed to development and application of the procedure based on registration of induced time-resolved chemiluminescence for detection of wide range of compounds in biology and medicine.

The procedure to be developed in this Project will be used for detection of trace amounts of various compounds including uranium and plutonium compounds in biological samples, such as blood, urine, hair, nails, and tissue samples. The results will be used for estimation of radiation and non-radiation risks including diagnostics at the issue, cell, and genome level.


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