TY - JOUR

T1 - Disordering of Starch Films as a Factor Influencing the Release Rate of Biologically Active Substances

AU - Podgorbunskikh, Ekaterina

AU - Kuskov, Timofei

AU - Matveeva, Anna

AU - Ulihin, Artem

AU - Bychkov, Aleksey

AU - Lomovskiy, Igor

AU - Polienko, Yuliya

N1 - Funding: Mechanical treatment of native starches and analyses of mechanically treated samples were supported by the grant of the President of the Russian Federation for governmental support of young Doctors of Sciences (project No. MD-2330.2022.1.3). The production of starch-based films, as well as the determination of the physicochemical properties of films, was supported by the state assignment to the Institute of Solid State Chemistry and Mechanochemistry SB RAS (project no. 121032500067-9).

PY - 2023/5/13

Y1 - 2023/5/13

N2 - The release of a spin probe (nitroxide radical) from polymer films was studied by electron paramagnetic resonance (EPR). The films were fabricated from starch having different crystal structures (A-, B-, and C-types) and disordering degrees. Film morphology (analysis of the scanning electron microscopy (SEM)) depended on the presence of dopant (nitroxide radical) to a larger extent rather than on crystal structure ordering or polymorphic modification. The presence of nitroxide radical led to additional crystal structure disordering and reduced the crystallinity index from the X-ray diffraction (XRD) data. Polymeric films made of amorphized starch powder were able to undergo recrystallization (crystal structure rearrangement), which manifested itself as an increase in crystallinity index and phase transition of the A- and C-type crystal structures to the B-type one. It was demonstrated that nitroxide radical does not form an individual phase during film preparation. According to the EPR data, local permittivity of starch-based films varied from 52.5 to 60.1 F/m, while bulk permittivity did not exceed 17 F/m, which demonstrates that local concentration of water is increased in the regions near the nitroxide radical. The mobility of the spin probe corresponds to small stochastic librations and is indicative of the strongly a mobilized state. The application of kinetic models made it possible to find out that substance release from biodegradable films consists of two stages: matrix swelling and spin probe diffusion through the matrix. Investigation of the release kinetics for nitroxide radical demonstrated that the course of this process depends on the type of crystal structure of native starch.

AB - The release of a spin probe (nitroxide radical) from polymer films was studied by electron paramagnetic resonance (EPR). The films were fabricated from starch having different crystal structures (A-, B-, and C-types) and disordering degrees. Film morphology (analysis of the scanning electron microscopy (SEM)) depended on the presence of dopant (nitroxide radical) to a larger extent rather than on crystal structure ordering or polymorphic modification. The presence of nitroxide radical led to additional crystal structure disordering and reduced the crystallinity index from the X-ray diffraction (XRD) data. Polymeric films made of amorphized starch powder were able to undergo recrystallization (crystal structure rearrangement), which manifested itself as an increase in crystallinity index and phase transition of the A- and C-type crystal structures to the B-type one. It was demonstrated that nitroxide radical does not form an individual phase during film preparation. According to the EPR data, local permittivity of starch-based films varied from 52.5 to 60.1 F/m, while bulk permittivity did not exceed 17 F/m, which demonstrates that local concentration of water is increased in the regions near the nitroxide radical. The mobility of the spin probe corresponds to small stochastic librations and is indicative of the strongly a mobilized state. The application of kinetic models made it possible to find out that substance release from biodegradable films consists of two stages: matrix swelling and spin probe diffusion through the matrix. Investigation of the release kinetics for nitroxide radical demonstrated that the course of this process depends on the type of crystal structure of native starch.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85160636326&origin=inward&txGid=32875f3d71be544d990150212aae711a

U2 - 10.3390/polym15102303

DO - 10.3390/polym15102303

M3 - Article

C2 - 37242877

VL - 15

JO - Polymers

JF - Polymers

SN - 2073-4360

IS - 10

M1 - 2303

ER -