**1. Introduction**

The Electron-Beam Plasma (EBP) is generated by injecting an electron beam (EB) into a gaseous medium. The EBP composition is complex: generally it contains molecules, atoms, radicals and ions in stable and excited states, plasma electrons and injected beam electrons as well. At moderate pressures (*Pm* <10 kPa) the EBP is strongly nonequilibrium. It means that the function of the electron energy distribution in the EBP is non-Maxwellian and heavy plasma particles mentioned above are produced in super-equilibrium concentrations, i. e. very high densities of ionized and excited particles can be reached. As a result, the EBP appears to be chemically active even at low temperature. With respect to non-equilibrium plasmas generated in conventional ways (for instance, the plasma of gas discharges) the EBP has the following advantages:


Due to its properties the EBP seems to be very promising for biomaterial treatment and especially for the modification of biopolymers.

The main objective of the study is to experimentally prove the applicability and advantages of the electron-beam plasma for actual biological, pharmacological, and medical problems.

The production of substances with novel biological and pharmacological properties on the base of EBP-modified proteins and polysaccharides is considered as example.

Bio-Medical Applications of the Electron-Beam Plasma 287

**2. The Electron-Beam Plasmachemical reactor and the treatment** 

For the controllable biopolymers modification and low molecular mass substances

Figure 1 illustrates the design and operation of the EBPR. The focused continuous EB *3*  generated by the electron-beam gun 1 which is located in the high vacuum chamber *2* is injected into the working chamber *5* filled with the plasma-generating gas through the specially designed double-stage gas-dynamic injection window *4* [6]. Oxygen, nitrogen, noble gases, gaseous hydrocarbons and other atomic and molecular gases, water vapor, and vapors of some organic substances can be used for the EBP generation. The electrically heated evaporator *11* is placed inside the reaction chamber, as shown in figure 1, to add the vapor to the plasma-generating gas. Evidently, the pure vapor can be used for the EBP generation and, in this case, the reaction chamber is kept at given constant pressure by

In passing through the gas the EB is scattered in elastic collisions and the energy of fast electrons gradually diminishes during various inelastic interactions with the medium (ionization, excitation, dissociation). As a result, the cloud *10* of the EBP is generated, all plasma parameters being functions of *x*, *y*, and *z* coordinates (*z* is the axis of the EB

1 – electron beam; 2 – high vacuum chamber; 3 – EB; 4 – injection window; 5 – working chamber; 6 – mixing layer of the powder to be treated; 7 – piezoceramic plate; 8 – temperature sensor; 9 – glass container; 10 – EBP cloud; 11 –

*x* 

1

2

3

4

5

6

7

*z* 

*y* 

**Figure 1.** The design of the plasmachemical reactor and the treatment procedure

12

production the special Electron Beam Plasmachemical Reactor (EBPR) was designed.

**procedure** 

adjusting the heater power.

water evaporator; 12 – scanning system.

9

10

11

injection).

The products of the fibrinogen proteolytic degradation are known to inhibit the platelet aggregation [1]. Being the product of the intermediate stage of the fibrinogen-fibrin polymer conversion, fibrin-monomer strongly affects the platelet activity due to two very active sites in its molecule. These sites are formed by the proteolytic cleavage in sequence the N-temini of the fibrinogen Aα and Bβ chains and release of the fibrinopeptides A and B [2]. Low molecular weight products of the fibrin-monomer proteolytic degradation are considered to be promising compounds for the platelets inhibition. Unfortunately the industrial fibrinmonomer can not be degradated by proteolytic enzymes (such as trypsin, plasmin, thrombin, and etc.) due to its high polymerization tendency. Therefore, the alternative techniques for controllable modification of the fibrin-monomer structure should be found to produce peptides with the high antiaggregating activity and without polymerization tendency.

The natural renewable biopolymers chitin and, especially, chitosan are very promising for technological and industrial applications such as agriculture, food processing, cosmetics production and others [3, 4]. Chitosan, linear heterocopolymers of β-1,4-linked 2-amino-2 deoxy-D-glucopyranose and 2-acet-amido-2-deoxy-D-glucopyranose units, has many unique biological properties namely high biocompatibility with living tissues, biodegrability, ability to the complexation, and low toxicity. In medicine and pharmaceutics the water-soluble low molecular weight chitosans (less than 10 kDa) are usually required. These substances can be used as immune response-modulating or antibacterial agents, sorbents, radioprotectors, and for the production of microcapsules, thing films, and substrates for cell cultures [3, 4]. To produce the low molecular weight chitosans (LMWC) several techniques, including chemical, enzymatic, and radical treatment have been suggested [5]. Simple and rather low-cost chemical treatment is a conventional method, however toxic wastes and environment contamination are inherent in the chemical chitin and chitosan processing as well as in all techniques mentioned above. Besides, the chemical treatment is very time consuming and usually takes several hours. Thus, the development of the effective techniques for quick and environment friendly chitosan degradation is the burning issue of the day.

The aims of the present study were as follows:

