Currently, the most urgent problem around the world is the treatment of bone defects resulting from injuries and diseases. An ideal material for bone tissue replacement should have the following properties: biocompatibility, optimal rate of biodegradation, bioinertness, the ability to release physiologically active substances and long-term protection against bacterial attack.
The aim of the work was to create fully synthetic biodegradable composites with polymodal drug release.
The basis for the implant was obtained by periodate oxidation of dextran according to the Malaprade reaction. After that, openly porous samples were obtained by preparing a conjugate of collagen with dialdehyde dextran, then it was mixed with water and various additives, freeze-dried and tableted. The pore size was determined by the polymer:water ratio and monitored by atomic force microscopy and microphotography. The rate of in vitro biodegradation was determined by the rate of release of L-hydroxyproline, since collagen contains a large amount of this amino acid. The study of osteoinductive properties in vivo was carried out according to the following method: a tablet of a given composition was placed in the tibia. Untreated demineralized bone matrix was placed in the other bone as a reference. Osteoinductive properties were monitored using tomography.
The results of atomic force microscopy and micrographs show that the resulting composite tablet mainly has pores with a diameter of 0.8-1 microns, which is optimal for the germination of capillaries and successful regeneration of bone tissue.
Based on in vitro experiments, it was found that the biodegradation of pure collagen under the action of collagenase takes 5 days. The use of dialdehyde dextran as a biodegradation inhibitor makes it possible to reduce the rate of enzymatic hydrolysis by three times.
Tomographic observations demonstrate that the material partially biodegraded, and callus began to form, which indicates the initial stage of bone fusion. The demineralized bone matrix was completely resorbed.
Thus, completely synthetic biodegradable, bone-replacing polymer composites based on dialdehyde dextran capable of releasing physiologically active substances at different times have been developed.