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Gradient Laser Fields in Biology

#B-479


Biophysical Application of Gradient Laser Fields: Development of Physical Principles and Study of the Influence on Biological Objects

Tech Area / Field

  • PHY-OPL/Optics and Lasers/Physics
  • BIO-CGM/Cytology, Genetics and Molecular Biology/Biotechnology
  • MED-RAD/Radiomedicine/Medicine
  • MED-OTH/Other/Medicine

Status
8 Project completed

Registration date
02.03.2000

Completion date
03.05.2005

Senior Project Manager
Horowicz L

Leading Institute
B.I. Stepanov Institute of Physics, Belarus, Minsk

Supporting institutes

  • Research Institute of Radiation Medicine and Endocrinology, Belarus, Minsk

Project summary

Objective: The objective of the project is to establish regularities and mechanisms of gradient laser fields action upon the structure and functional properties of biological objects (enzymes, animal and human cells in tissue cultures, human erythrocytes, animal tissues) and to develop on this basis recommendations on applications of these fields in medicine for therapeutic treatment.

Main idea. The idea of the project consists in investigation of the effect of gradient laser fields (i.e. laser fields with strong spatial variations of intensity) on biological objects. It is well known that an object placed in a gradient light field is effected by forces resulting from a gradient of the interaction energy of the electromagnetic field with the object. Presently, gradient laser fields are employed in laser tweezers for precision translation of biological micro-objects. At the same time, the problem of the gradient light fields influence on functioning of biological systems, in particular, on the human organism, remains unexplored. This problem is of a great practical importance because the strong spatial gradients are characteristic and distinctive features of illumination of any subject with coherent light. The gradients manifest themselves as irregular speckles on the subject surface originated from the interference and diffraction of the incident light at its interaction with the subject. On the other hand, using various schemes of laser beams interference, one may purposely realize a spatial modulation of radiation with controllable period. This opens many new possibilities for action of laser radiation on biological systems. The gradient structure of the laser field and the resulting gradient forces should lead to two basic effects:


1) change in the local concentration of certain biological components of the micrometer scale (separate cells, organelles, large biomolecules etc.);

2) stimulation of conformational changes in various biological structures both within a cell and on the supracellular level. These effects can change the character of the cell metabolism and quite probably the DNA structure, which is of the vital importance for living organism.

State of the art. Low-intensity laser radiation is widely used for a long period of time in medicine for therapy of various diseases. Radiation employed for these purposes typically does not induce neither photochemical reaction, nor noticeable heating of the organ irradiated. Nevertheless, numerous experts believe that irradiation with low-intensity laser sources leads to many healing effects. Despite a vast number of publications in this field and a substantial positive experience on application of low-intensity laser radiation in therapy of various diseases, the primary mechanism of the low-intensity laser radiation action on the human organism still remains unclear. The lack of the generally accepted, scientifically substantiated approach to explanation of the observed medical phenomena frequently evokes doubts in their objective existence and impedes the practical use and development of the laser therapy methods. On the other hand, the action of gradient forces on micro-object placed in a focal spot of a focussed laser beam, is well established and is widely used in a laser tweezers. However manifestation of gradient forces at interaction of interference laser fields with heterogeneous media and the action of such fields on a structure and vital functions of biological systems remain unexplored.

Aims and expected results of the project. The main aims of the project are:


1) to develop physical principles and theoretical description of gradient light fields interaction with heterogeneous media of various origin;

2) to investigate experimentally the physical phenomena caused by action of gradient laser fields on heterogeneous media simulating biological objects;

3) to study the impact of spatially modulated laser radiation on biological objects of various types (the structure and functioning of cells, parameters of erythrocyte membranes, efficiency of enzymes action, reparation of test animals living tissues, etc.). The possibility of gradient laser fields application for weakening the effect of radioactive irradiation on human organism will be also considered. As a result, the pilot technology for application of interference laser fields, including Bessel beams, for biological purposes and therapeutic use in medicine will be developed. In addition, requirements for genetic safety at commercial application of laser radiation will have been determined.

Impact on the progress in the field. The investigation of the gradient laser fields influence on biological objects will allow to reveal basically new mechanisms of the laser radiation action on a living organism. Such mechanisms differ from the conventional photochemical interaction of light with matter, as there is no light quanta absorption by biological components involved in the process. Investigation of this problem is extremely important from the practical viewpoint, since it will allow to provide scientific grounds for the presently existing laser therapy methods as well as for development of novel approaches for laser use in medicine, based on use of gradient laser fields. In addition, in view of ever-expanding household and medical use of coherent light sources, it is imperative to investigate the problem of genetic safety at applications of lasers as the laser irradiation always produce high spatial gradients of intensity. The obtained results will also allow to propose novel methods of heterogeneous systems analysis and novel laser technologies for creating new materials with spatially modulated parameters.

Competence of the project crew and meeting ISTC goals and objectives. 24 persons will participate in the project, of which 15 (including seven doctors of science, five candidates of science, two USSR State Prize winners, and a Belarus State Prize winner in physics) were formerly involved in the field of military research. All participants will be completely reoriented to the problems of the Project, which have a high social importance and deeply humane aim. For Belarus, where the problem of overcoming the consequences of the Chernobyl accident still remains very actual, this project has a special importance, since one of its goals is the development of new methods of reducing the effect of radioactive irradiation by means of application of gradient laser fields. The realization of the project will promote integration of the scientists from Belarus into the international scientific community via cooperation with collaborators and due to possibilities to attend scientific conferences. It is also assumed that in future, the present research will serve as a basis for creating novel laser therapy devices whose production and distribution will serve in favor of development of market relationships in Belarus. The countries financing the given project, will have first priority in using the obtained outcomes for medical purposes, not bearing additional financial expenditures.

Scope of Activities. The fulfillment of the project will take three years. Total amount of work under the Project will make 486 man*mths, including 294 man*mths for the experts, before participating in development of weapons.

Role of foreign collaborators. All collaborators will be regularly supplied with scientific and technical information on the project results. To each collaborator the possibility will be granted to use in their scientific activity and medical practice the techniques and equipment developed in a course of the Project fulfillment. Joint symposia and workshops will be carried out to discuss the observed effects and to specify their possible medical applications. Joint research on problems of fluorescent probes in bio-membranes, optical nonlinearity in heterogeneous media, use of gradient laser fields in biology and medicine, will be also carried out with the specified above collaborators.

Technical approach and methods. Theoretical investigations will be carried out on the basis of the Fokker–Planck equation formalism and quantum-mechanical methods of calculations of polarizability of micro-particles of various origin. Experimental study of the optical manifestation of the concentration nonlinearity effects will be carried out in different heterogeneous media (calibrated polymer micro-spheres in liquid, various suspensions and emulsions, polymer solutions, etc.). In biological part of the project the enzymes, human erythrocytes, skin and muscle tissue cells of human embryos, kidney cells of Ma ape in a tissue culture, and test animals will be used as objects of investigations. Biological effect on culture of cells will be estimated by proliferation and by rate of nuclein acids synthesis. Mutagenic and antimutagenic effects of laser radiation on cells will be estimated by observation of the number of chromosome aberrations in piding cells. Classical methods of cytogenetic analysis, fluorescence in-situ hybridization, micro-nuclear tests, flow cytofluorimetry methods and other experimental techniques will be employed.


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