Chlorogenic Acid Containing Bioinspired Polyurethanes: Biodegradable Medical Adhesive Materials

Bismuth Tungstate-Silver Sulfide Z-Scheme Heterostructure Nanoglue Promotes Wound Healing through Wound Sealing and Bacterial Inactivation

Rapid wound closure and bacterial inactivation are effective strategies to promote wound healing. Herein, a versatile nanoglue, bismuth tungstate (Bi₂WO₆)-silver sulfide (Ag₂S) direct Z-scheme heterostructure nanoparticles (BWOA NPs), was designed to accelerate wound healing. BWOA NPs' hollow structure and rough surface could effectively close wound tissues acting as a barrier between external bacteria and the wound. More importantly, the unique Z-scheme heterostructure endows BWOA NPs with an effective electron and hole separating ability with potent redox potential, where electrons and holes could effectively react with water and oxygen to produce reactive oxygen species, leading to a higher antibacterial activity against both endogenous and external bacteria at the wound site. A series of in vitro and in vivo biological assessments demonstrated that BWOA NPs could rapidly close wounds and promote wound healing. With sunlight irradiation, the inhibiting rates of BWOA NPs against Escherichia coli and Staphylococcus aureus are 61.62 ± 2.85 and 73.40 ± 3.28%, respectively. Also, the wound healing rate in BWOA NP-treated mice is 25.90 ± 5.85% higher than PBS. This design provides a new effective strategy to promote bacterial inactivation and accelerate wound healing.

Photocrosslinkable gelatin/collagen based bioinspired polyurethane-acrylate bone adhesives with biocompatibility and biodegradability

Hard or soft tissue adhesives have been presented as a promising candidate to replace traditional wound closure methods. However, there are mechanical strength problems in biological adhesives and biocompatibility problems in synthetic-based adhesives. At this point, we aimed to remove all these disadvantages and produce a single adhesive that contains all the necessary features and acrylate functionalized UV-curable polyurethane formulations were produced with high crosslink density, high adhesion strength, biocompatibility and injectable property for easy application as potential biomedical adhesives. Aliphatic isophorone diisocyanate (IPDI) was used as the isocyanate source and β-cyclodextrin was used for host-guest relationship with gentamicin by crosslinking. Proteins (gelatin (GEL), collagen (COL)) and PEGs of various molecular weight ranges (P200, P400, P600) were selected as the polyol backbone for polyurethane synthesis due to their multiple biological activities such as biocompatibility, biodegradability, biomimetic property. Several techniques have been used to characterize the structural, thermal, morphological, and various other physicochemical properties of the adhesive formulations. Besides, the possibility of its use as a hard tissue adhesive was investigated by evaluating the tissue adhesion strength in vitro and ex vivo via a universal testing analyzer in tensile mode. Corresponding adhesive formulations were evaluated by in vitro and in vivo techniques for biocompatibility. The best adhesion strength results were obtained as 3821.0 ± 214.9, and 3722.2 ± 486.8 kPa, for IPDI-COL-P200 and IPDI-GEL-P200, respectively. Good antibacterial activity capability toward Escherichia coli Pseudomonas aeruginosa, and Staphylococcus aureus were confirmed using disc diffusion method. Moreover, cell viability assay demonstrated that the formulations have no significant cytotoxicity on the L929 fibroblast cells. Most importantly, we finally performed the in vivo biodegradability and in vivo biocompatibility evaluations of the adhesive formulations on rat model. Considering their excellent cell/tissue viability, fast curable, strong adhesion, high antibacterial character, and injectability, these adhesive formulations have significant potential for tissue engineering applications.

Tissue Adhesives: From Research to Clinical Translation

Sutures, staples, clips and skin closure strips are used as the gold standard to close wounds after an injury. In spite of being the present standard of care, the utilization of these conventional methods is precarious amid complicated and sensitive surgeries such as vascular anastomosis, ocular surgeries, nerve repair, or due to the high-risk components included. Tissue adhesives function as an interface to connect the surfaces of wound edges and prevent them from separation. They are fluid or semi-fluid mixtures that can be easily used to seal any wound of any morphology - uniform or irregular. As such, they provide alternatives to new and novel platforms for wound closure methods. In this review, we offer a background on the improvement of distinctive tissue adhesives focusing on the chemistry of some of these products that have been a commercial success from the clinical application perspective. This review is aimed to provide a guide toward innovation of tissue bioadhesive materials and their associated biomedical applications.

Design of Xylose-Based Semisynthetic Polyurethane Tissue Adhesives with Enhanced Bioactivity Properties

Developing biocompatible tissue adhesives with high adhesion properties is a highly desired goal of the tissue engineering due to adverse effects of the sutures. Therefore, our work involves synthesis, characterization, adhesion properties, protein adsorption, in vitro biodegradation, in vitro and in vivo biocompatibility properties of xylose-based semisynthetic polyurethane (NPU-PEG-X) bioadhesives. Xylose-based semisynthetic polyurethanes were developed by the reaction among 4,4'-methylenebis(cyclohexyl isocyanate) (MCI), xylose and polyethylene glycol 200 (PEG). Synthesized polyurethanes (PUs) showed good thermal stability and high adhesion strength. The highest values in adhesion strength were measured as 415.0 ± 48.8 and 94.0 ± 2.8 kPa for aluminum substrate and muscle tissue in 15% xylose containing PUs (NPU-PEG-X-15%), respectively. The biodegradation of NPU-PEG-X-15% was also determined as 19.96 ± 1.04% after 8 weeks of incubation. Relative cell viability of xylose containing PU was above 86%. Moreover, 10% xylose containing NPU-PEG-X (NPU-PEG-X-10%) sample has favorable tissue response, and inflammatory reaction between 1 and 6 weeks implantation period. With high adhesiveness and biocompatibility properties, NPU-PEG-X can be used in the medical field as supporting materials for preventing the fluid leakage after abdominal surgery or wound closure.