Oxygen-generating smart hydrogels supporting chondrocytes survival in oxygen-free environments.

Cartilage is one of our body's tissues which are not repaired automatically by itself. Problems associated with cartilage are very common worldwide and are considered the leading cause of pain and disability. Smart biomaterial or "Four dimensional" (4D) biomaterials has started emerging as a suitable candidate, which are principally three dimensional (3D) materials that change their morphology or generate a response measured at space and time to physiologic stimuli. In this context, the release of oxygen through hydrogels in contact with water is considered as 4D biomaterials. The objective of this study is to develop strategies to release oxygen in a sustainable and prolonged manner through hydrogels systems to promote chondrocytes survival in oxygen-free environment. The 4D biomaterials are engineered from gelatin methacryloyl (GelMA) loaded with calcium peroxide (CPO), which have the ability to generate oxygen in a controlled and sustained manner for up to 6 days. The incorporation of CPO into the hydrogel system provided materials with enhanced mechanical and porosity properties. Furthermore, the hydrogels promoted chondrocyte survival and reduced cell death under oxygen-free conditions.

Dual effective core-shell electrospun scaffolds: Promoting osteoblast maturation and reducing bacteria activity.

Herein, we electrospun ultrathin core-shell fibers based on polycaprolactone (PCL), polyethylene glycol (PEG), gelatin and osteogenic growth peptide (OGP), and evaluated their potential to upregulate human osteoblast cells (hFOB) and to reduce Gram-positive and Gram-negative bacteria. We also evaluated the fiber morphology, chemical structure and peptide delivery efficacy. The employment of core-shell fibers compared to fibers without a core-shell showed improved mechanical strength, comparable to the strength of pure PCL, as well as improved hydrophilicity and wettability. The careful selection of polymer combination and core-shell strategy promoted a controlled and sustained release of OGP. Moreover, increased calcium deposition (CD) (1.3-fold) and alkaline phosphate (ALP) activity was observed when hFOBs were cultivated onto core-shell fibers loaded with OGP after 21 days of culture. Our developed scaffolds were also able to reduce the amount of Pseudomonas aeruginosa (ATCC 25668) bacteria by a factor of two compared to raw PCL without the use of any antibiotics. All of these results demonstrate a promising potential of the developed core-shell electrospun scaffolds based on PCL:PEG:Gelatin:OGP for numerous bone tissue applications.

Understanding the impact of crosslinked PCL/PEG/GelMA electrospun nanofibers on bactericidal activity.

Herein, we report the design of electrospun ultrathin fibers based on the combination of three different polymers polycaprolactone (PCL), polyethylene glycol (PEG), and gelatin methacryloyl (GelMA), and their potential bactericidal activity against three different bacteria Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), and Methicillin-resistant Staphylococcus aureus (MRSA). We evaluated the morphology, chemical structure and wettability before and after UV photocrosslinking of the produced scaffolds. Results showed that the developed scaffolds presented hydrophilic properties after PEG and GelMA incorporation. Moreover, they were able to significantly reduce gram-positive, negative, and MRSA bacteria mainly after UV photocrosslinking (PCL:PEG:GelMa-UV). Furthermore, we performed a series of study for gaining a better mechanistic understanding of the scaffolds bactericidal activity through protein adsorption study and analysis of the reactive oxygen species (ROS) levels. Furthermore, the in vivo subcutaneous implantation performed in rats confirmed the biocompatibility of our designed scaffolds.