Investigation on Swelling of Agar-Based Antibacterial Hydrogels for Hard-To-Heal Wound Dressings.

Despite a wide range of available wound treatments, hard-to-heal wounds still pose a challenge. Hydrogels are often used as dressings for these wounds, because they sustain moisture in the wound environment, supporting the natural healing process. However, it is still not fully understood how physicochemical properties of hydrogel matrix affect the drug release process. Thus, detailed swelling kinetics examination coupled with modeling is needed together with studies on drug release. In this regard, several hydrogels based on plant-derived agar and modified with amikacin were investigated. The main properties of hydrogels were examined focusing on detailed swelling kinetics. Drug release was studied as microbiological activity against E. coli and S. Epidermidis strains. The obtained hydrogels were characterized by high swelling, reaching values in range from 465 to 1300%, fitting the second order kinetics mode and exhibiting the quasi-Fickian diffusion properties. Furthermore, there was no correlation found between swelling properties and antibacterial activity against tested strains. The results confirmed that presented hydrogel materials have desirable properties for application as dressings for hard-to-heal wounds. The suggested compositions are a promising base for modification with other active substances (e.g., regenerative, anti-inflammatory) and studying the broader correlation between swelling and drug release.

Polyurethane based hybrid ciprofloxacin-releasing wound dressings designed for skin engineering purpose.

PURPOSE: Even in the 21st century, chronic wounds still pose a major challenge due to potentially inappropriate treatment options, so the latest wound dressings are hybrid systems that enable clinical management, such as a hybrid of hydrogels, antibiotics and polymers. These wound dressings are mainly used for chronic and complex wounds, which can easily be infected by bacteria. MATERIALS AND METHODS: Six Composite Porous Matrices (CPMs) based on polyurethane (PUR) in alliance with polylactide (PLAs) and poly(vinyl alcohol) (PVA) were prepared and analyzed using optical microscopy. Three different types of hydrogels and their Ciprofloxacin (Cipro) modified variants' ratios were prepared and analyzed using FTIR, SEM and EDX techniques. Six Hybrid Cipro-Releasing Hydrogel Wound Dressings (H-CRWDs) were also prepared and underwent short-term degradation, Cipro release, microbiology and cell viability measurements. RESULTS: Average porosity of CPMs was in the range of 69-81%. The pore size of the obtained CPMs was optimal for skin regeneration. Short-term degradation studies revealed degradability in physiological conditions regardless of sample type. A meaningful release was also observed even in short time (21.76 â€‹± â€‹0.64 â€‹µg/mL after 15 â€‹min). Microbiological tests showed visible inhibition zones. Cell viability tests proved that the obtained H-CRWDs were biocompatible (over 85% of cells). CONCLUSIONS: A promising hybrid wound dressing was labeled. Simple and cost-effective methods were used to obtain microbiologically active and biocompatible dressings. The results were of importance for the design and development of acceptable solutions in the management of chronic wounds of high potential for infection.

Composite Polyurethane-Polylactide (PUR/PLA) Flexible Filaments for 3D Fused Filament Fabrication (FFF) of Antibacterial Wound Dressings for Skin Regeneration.

This paper addresses the potential application of flexible thermoplastic polyurethane (TPU) and poly(lactic acid) (PLA) compositions as a material for the production of antibacterial wound dressings using the Fused Filament Fabrication (FFF) 3D printing method. On the market, there are medical-grade polyurethane filaments available, but few of them have properties required for the fabrication of wound dressings, such as flexibility and antibacterial effects. Thus, research aimed at the production, characterization and modification of filaments based on different TPU/PLA compositions was conducted. The combination of mechanical (tensile, hardness), structural (FTIR), microscopic (optical and SEM), degradation (2 M HCl, 5 M NaOH, and 0.1 M CoCl2 in 20% H2O2) and printability analysis allowed us to select the most promising composition for further antibacterial modification (COMP-7,5PLA). The thermal stability of the chosen antibiotic-amikacin-was tested using processing temperature and HPLC. Two routes were used for the antibacterial modification of the selected filament-post-processing modification (AMI-1) and modification during processing (AMI-2). The antibacterial activity and amikacin release profiles were studied. The postprocessing modification method turned out to be superior and suitable for wound dressing fabrication due to its proven antimicrobial activity against E. coli, P. fluorescens, S. aureus and S. epidermidis bacteria.

Polypropylene structure alterations after 5 years of natural degradation in a waste landfill.

Up to 25% of plastic waste in Europe is still disposed of in landfills, despite recycling efforts. The plastic waste in the landfill plot may be exposed both to abiotic and biotic degradation processes, although it is thought that most of the plastic materials tend to be resistant to biodegradation or biodeterioration even after a long time. To verify if polypropylene (PP) can undergo the process of short-term biodegradation and how this process is manifested in a municipal waste landfill, we collected a plastic sample from an already closed landfill plot estimating its age at approximately 5 years. Fourier-Transform Infrared Spectroscopy led to sample identification as PP as well as showed additional bands which are not specific to polymer structure but rather result from microbial metabolism. Differential Scanning Calorimetry was performed to examine the influence of the environmental degradation process on the degree of crystallisation of the tested PP. Moreover, significant changes on the surface of an old PP packaging were observed with Scanning Electron Microscopy (SEM) showing clear signs of PP delamination which resulted in microplastic particles formation (smaller than 5 µm in diameter). Additionally, several round and oval shaped structures were observed with SEM leading to the suspicion of biofilm formation on the PP surface. Indeed, the microorganisms were present in a vast amount on the old PP surface and possibly formed a viable biofilm as it was confirmed with fluorescence microscopy. These data show that plastic waste can be inhabited by microorganisms from the ambient environment which may probably lead to its faster degradation. However, this process should be investigated in more detail in order to shed light upon the possible risk factors of plastic biodegradation in waste landfills to the environment and human health. Even after five years, polypropylene can undergo deterioration/biodegradation in a waste landfill with viable microbial cells on its surface, possibly involved in its degradation.