Recently, polylactide (PLA) ultrathin films were developed for biomedical applications as wound dressings and a part of tissue engineering constructs. Owing to many excellent properties such as sufficient flexibility, biodegradability, adhesiveness, and transparency, the films displayed an efficient ability to prevent bacterial penetration into the wound. In this work, silver nanoparticles (SNPs) with the particle size of 2-3 nm were used as an antibacterial agent. The homogeneous ultrathin films of SNP/PLA nanocomposite were prepared with a thickness of 100-700 nm and the concentration of SNPs up to 10 wt%. The films exhibited strong antibacterial activity against S. aureus, E. coli and B. subtilis. Although the addition of a large amount of SNPs into the neat PLA leads to decreases in tensile strength, elongation at fracture and Young's modulus, the SNP/PLA ultrathin films could be potentially used as an antimicrobial wound dressing for tissue regeneration.
Multifunctional 3D-printed holey structures made of composite polymers loaded with nanocarbon were designed to serve simultaneously as GHz-radiation absorbing layers and heat conductors. The geometry of the structures was devised to allow heat to be easily transferred through, with special attention paid to thermal conductivity. Numerical calculations and a simple homogenization theory were conducted in parallel to address this property. Different structures have been considered and compared. The electromagnetic shielding effectiveness of the produced holey structures was measured in the microwave range.
Phenol formaldehyde resin (PFR) based composites with multiwalled carbon nanotube (MWCNT) additives (2 and 5 wt.%) were prepared and their electromagnetic (EM) properties were investigated in Ka-band frequency range (26-37 GHz). It was demonstrated that the combination of such materials in a double-layered structure allows achievement of the significant attenuation of EM radiation. The electromagnetic response of considered double-layered system was modeled by solving the electric field integral equation, utilizing the Green's function technique. Absorption up to 96% in the 26-37 GHz frequency band was both predicted and experimentally observed.
Pectin‐Ag nanocomposites with a core‐shell structure are synthesized by the “green chemistry” method based on the reduction of silver nitrate with pectin (amidated, low‐, or high methoxylated) in an alkaline medium at room temperature. TEM and DLS measurements show that the average size of the inorganic core (10–30 nm) and hydrodynamic diameter of the nanocomposite (284.8–649.2 nm) depend on the type of pectin. The films based on pectin‐Ag nanocomposites and polyvinyl alcohol (PVA) with different molecular weight (30, 66, and 145 kDa) are obtained by casting evaporation technique. A comparative study of their mechanical, optical, degradation and antibacterial properties is carried out. The films with the smaller size of Ag nanocomposite exhibit higher antimicrobial activity against Bacillus strains. The pectin‐Ag/PVA films are loaded with antibiotic kanamycin (KAN). Prolonged release of antibiotic and pronounced (up to full inhibition) antimicrobial effect of pectin‐Ag/PVA/KAN films against Escherichia coli, Pseudomonas aeruginosa, Bacillus pumilus, and Bacillus subtilis is due to the formation of pectin‐Ag/KAN complexes. Moreover, pectin‐Ag/PVA/KAN films show high potency against resistant strains Pseudomonas aeruginosa. The obtained multifunctional films are expected to find promising applications in biomedical engineering and wound healing.
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