Bionanotechnologists proved that adding excipients to biopolymers, which are used in medicine as new dosage forms, can change its crystallinity and physical characteristics. Results indicate the possibility of regulating the resilience to biodegradation. For instance, when controlling the release of medicine from biopolymer composite. The results are published in the Polymers.
An important objective of modern medicine is to create new dosage forms using long biopolymers, which provide a means of transporting medicine to the required point. In order to do that, the polymers have to be completely harmless and biodegradable. That way the biopolymer delivers the medicine, gradually releases it, and then harmlessly dissolves leaving no traces. The velocity of this diffusion determines the dosage forms’ effectiveness. It is called kinetic profile. The researchers’ primary focus here is to pinpoint how the kinetic profile changes within the polymer changing its structure. Scientists from RUDN and their colleagues have found the answer for poly-3-hydroxybutyrate (PHB) — one of the most common polymers.
“The use of nanotechnologies in medicine, transition towards new dosage forms, ultra-thin implants and diagnostic systems, — we need bio-based polymeric materials for that. They have to be completely biodegradable, with no toxic reaction products. The diffusion of medicine is dependent on the polymer’s structure, that’s why morphology and crystallinity define its kinetic profile and ultimately the dosage forms’ effectiveness,” said Alexander Vetcher, PhD, Deputy Director of the "Nanotechnologies" center of RUDN University.
Bionanotechnologists defined how PHB properties are changed by adding tetraphenylporphyrin (TPP) and complexes TPP+tin and TPP+iron. These commonly used in nano-medicine compounds are photocatalytic and have antibacterial peculiarity. The scientists have found out that the TPP compound changes the crystalline structure of nanomolecules: level of crystallinity, molecular mobility and other criteria. At the same time, the polymers’ qualities also change, for example, its reaction under high temperature or when exposed to water.
Scientists analyzed the PHB crystalline structure with TPP complexes by means of X-ray diffraction, which scans with electronic and anatomic force microscopy, differential scanning calorimetry and other. The scientists have also examined polymers’ behavior when annealing at a temperature of up to 140 ℃ and in the aquatic environment.
“The study showed that by adding TPP complexes to PHB we can dramatically change the geometry and morphology of the polymer fibers. Annealing the ultra-thin fibers of such polymer or exposing it to an aquatic environment seriously affects the structure of the polymers’ amorphous and crystalline areas. More importantly, these structure changes rely on the character and the amount of additives. These results should be taken into account when developing sterilization regime of medical equipment made of PHB,” said Alexander Vetcher, PhD, Deputy Director of the "Nanotechnologies" center of RUDN University.
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