Hydrogels for biomedical applications.

Being designated to protect other tissues, skin is the first and largest human body organ to be injured and for this reason, it is accredited with a high capacity for self-repairing. However, in the case of profound lesions or large surface loss, the natural wound healing process may be ineffective or insufficient, leading to detrimental and painful conditions that require repair adjuvants and tissue substitutes. In addition to the conventional wound care options, biodegradable polymers, both synthetic and biologic origin, are gaining increased importance for their high biocompatibility, biodegradation, and bioactive properties, such as antimicrobial, immunomodulatory, cell proliferative, and angiogenic. To create a microenvironment suitable for the healing process, a key property is the ability of a polymer to be spun into submicrometric fibers (e.g., via electrospinning), since they mimic the fibrous extracellular matrix and can support neo- tissue growth. A number of biodegradable polymers used in the biomedical sector comply with the definition of bio-based polymers (known also as biopolymers), which are recently being used in other industrial sectors for reducing the material and energy impact on the environment, as they are derived from renewable biological resources. In this review, after a description of the fundamental concepts of wound healing, with emphasis on advanced wound dressings, the recent developments of bio-based natural and synthetic electrospun structures for efficient wound healing applications are highlighted and discussed. This review aims to improve awareness on the use of bio-based polymers in medical devices.

https://www.mdpi.com/2079-4983/11/3/67/pdf

Bio-Based Electrospun Fibers for Wound Healing.

Some of the currently used wound dressings have interesting features such as excellent porosity, good water-absorbing capacity, moderate water vapor transmission rate, high drug loading efficiency, and good capability to provide a moist environment, but they are limited in terms of antimicrobial properties. Their inability to protect the wound from microbial invasion results in wound exposure to microbial infections, resulting in a delayed wound healing process. Furthermore, some wound dressings are loaded with synthetic antibiotics that can cause adverse side effects on the patients. Natural-based compounds exhibit unique features such as good biocompatibility, reduced toxicity, etc. Curcumin, one such natural-based compound, has demonstrated several biological activities such as anticancer, antibacterial and antioxidant properties. Its good antibacterial and antioxidant activity make it beneficial for the treatment of wounds. Several researchers have developed different types of polymer-based wound dressings which were loaded with curcumin. These wound dressings displayed excellent features such as good biocompatibility, induction of skin regeneration, accelerated wound healing processes and excellent antioxidant and antibacterial activity. This review will be focused on the in vitro and in vivo therapeutic outcomes of wound dressings loaded with curcumin.

https://www.mdpi.com/2073-4360/12/10/2286/pdf

Polymer-Based Materials Loaded with Curcumin for Wound Healing Applications.

Visible Light-Induced 3D Bioprinting Technologies and Corresponding Bioink Materials for Tissue Engineering: A Review

Hydrogels are fascinating soft materials with unique properties. Many biological systems are based on hydrogel-like structures, underlining their versatility and relevance. The properties of hydrogels strongly depend on the structure of the building blocks they are composed of, as well as the nature of interactions between them in the network structure. Herein, gel networks made by supramolecular interactions are compared to covalent macromolecular networks, drawing conclusions about their performance and application as responsive materials.

/pdf/pros-and-cons-supramolecular-or-macromolecular-what-is-best-57yuenaori.pdf

Pros and Cons: Supramolecular or Macromolecular: What Is Best for Functional Hydrogels with Advanced Properties?

The effect of molecular weight and content of PEG on in vitro drug release of electrospun curcumin loaded PLA/PEG nanofibers

Chitosan, as a natural polysaccharide, has a unique structure and multi-functional properties. One of the most prominent specifications of chitosan is high biocompatibility, good biodegradability, low toxicity and antibacterial and antiallergenicity properties. Chitosan has a high potential for controlled drug delivery. Therefore, investigating the loading capacity and release rate of chitosan at different conditions is important. By reducing particle size, chitosan has shown a high ability of teicoplanin loading due to its cationic property, which is important in this research. The aim of this study was to investigate chitosan nanoparticle potential for use in biomedical devices for drug delivery systems. Nanoparticles were prepared by ionic gelation with tripolyphosphate (TPP) ion, and the factors that affected chitosan nanoparticle size were investigated. The prepared samples were characterized using DLS, FTIR, TGA, DSC and XRD techniques. It is found at best condition with CS/TPP ratio of 2:1 nanoparticles were obtained at an average size of about 100 nm. The results confirmed that the drug (teicoplanin) loaded on the TPP cross-linked chitosan nanoparticles causes an increase in nanochitosan size and there was no interaction between teicoplanin and chitosan. Also, it is observed that 28.2% of teicoplanin was released in the first 10 h and the release is continued gradually to receive 37.4% in 100 h. Thus, it seems that chitosan nanoparticles mitigate the drug release and are suitable for sustained drug release.

Synthesis and characterization of chitosan nanoparticles containing teicoplanin using sol–gel

Novel strategies have been proposed to enhance the quality of surgery by scheming noninvasive methods. For this reason, photo-curable in situ forming hydrogels have been well developed during advancements in the regenerative medicine. In this study, polyethylene glycol itaconate (PEGI) was synthesized by reacting polyethylene glycol (PEG) with different molecular weights (1000, 4000 and 8000 $$\hbox {g mol}^{-1}$$) and itaconyl chloride. The synthesized PEGIs were fully characterized and employed as a macromonomer for the preparation of in situ forming hydrogels using a combination of camphorquinone and dimethylaminoethyl methacrylate as a reactive photoinitiator system, and hydroxyethyl methacrylate as a reactive diluent. The physical properties of the hydrogels including gel yield, equilibrium swelling and compressive strength were determined. The hydrogel based on PEG 4000 with a gel yield of 86%, a water uptake of 103%, a compressive modulus of 11.2 MPa, an elongation at break of 9% and a curing time of 4 min was selected for the encapsulation of rabbit articular chondrocyte cells. The cytocompatibility of the in situ formed hydrogels was evaluated using 3[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide, live-dead fluorescence assays and optical microscopy observations. Glycosaminoglycans were quantified by dimethylmethylene blue staining from the encapsulated chondrocytes after 14 days. The proposed in situ forming hydrogel can be considered as an injectable and photocurable carrier for cell delivery in cartilage tissue engineering.

/pdf/in-situ-forming-hydrogels-based-on-polyethylene-glycol-3pf6x3orxf.pdf

In situ forming hydrogels based on polyethylene glycol itaconate for tissue engineering application

The aim of this study was to prepare and characterize eugenol-loaded oligochitosan nanoparticles (Eu/Oc) via sol–gel and emulsion/sol–gel methods using tripolyphosphate (TPP) as cross-linking agent. The effect of different parameters on the particle size of nanoparticles was investigated. Purified oligochitosan (Oc) was first characterized by FT-IR and TGA methods. The increase in TPP concentration, Oc concentration, the mass ratio of Oc to TPP, and diameter of the reactor resulted in larger particles while increasing the stirring rate decreased the particle size down to a minimum level. The rate of the addition of TPP solution showed no significant effect on the particle size. The yield of nanoparticle formation was calculated as 52 ± 3%. The stability of the dispersion containing the produced nanoparticles was also investigated. The optimum particle size and the loading yield of eugenol in nanoparticles were calculated as 270 ± 45 nm and 10%, respectively. In emulsion method, emulsifier and cross-linker concentration play important roles in nanoparticles’ size and should be optimized. The results showed that particle size increases at concentrations lower and higher than the optimum value. The optimum particle size in this method was obtained as 123 ± 23 nm.

Mehrnoosh Hasan Shahriari

Papers

The effect of molecular weight and content of PEG on in vitro drug release of electrospun curcumin loaded PLA/PEG nanofibers

Synthesis and characterization of chitosan nanoparticles containing teicoplanin using sol–gel

In situ forming hydrogels based on polyethylene glycol itaconate for tissue engineering application

Preparation and characterization of eugenol-loaded oligochitosan nanoparticles through sol–gel and emulsion/sol–gel methods