**5. Conclusions**

142 Materials Science and Technology

The spongious matrix of CG/ PB/ MA-MMA nanocomposite was *in vitro* tested on osteoblast cell cultures. *In vitro* test results are presented in Table 5. After 24 and 72 hours since hatching, the cells proliferate on matrix surface, the viability being of 97%, very close to the reference value (control sample). These results are also supported by microscopy observation of cellular density (Fig. 11). The collagen/layered silicate/MA-MMA ternary nanocomposite does not

DO 550nm

Control Porous matrix of nanocomposite

CONTROL 1.0263 100%

matrix pH 7 0.9954 97% Table 5. Proliferation and osteoblast cells viability hatched on matrix of CG/ PB/ MA-MMA

> 10x 10x After 24 hours since hatching

20X 20X After 72 hours from hatching Fig. 11. Microscopic analysis of osteoblast culture samples sowed on CG/ PB/ MA-MMA

ternary nanocomposite substrate after 24 and 72 hours since hatching.

Viability from control sample, (%)

present any citotoxic response and the cells present normal phenotype.

Sample Optical density

CG/ PB- MA-MMA nanocomposite

nanocomposites.

The key results consist in obtaining new types of collagen nanostructured biomaterials in the form of spongious, microporous matrices, nontoxic and biocompatible with osteoblast cells. The preparation of the new nanocomposites is based on the use of two natural components: collagen, which contributes to bone regeneration and natural layered silicate (montmorillonite) which improves the thermal resistance of collagen, able to release in time an active substance at low and controlled concentrations. Maleic copolymers favour the silicate dispersion in the matrix of collagen and the obtaining of intercalated partially exfoliated nanocomposites with disordered lamellar structure. The nanocomposites in form of microporous matrix (scaffold) obtained by dispersion of binary nanocomposites in collagen gel have a spongy structure which contains macro and micro interconnected nanopores, similar with extra cellular matrix, which allows the penetration of the physiological fluids, necessary for the growth of cells. In comparison with collagen matrix, CG/ PB-MA-MMA nanocomposites have improved thermal stability.
