Nowadays, despite remarkable progress in developing bone tissue engineering products, the fabrication of an ideal scaffold that could meet the main criteria, such as providing mechanical properties and suitable biostability as well as mimicking the bone extracellular matrix, still seems challenging. In this regard, utilizing combinatorial approaches seems more beneficial. Here, we aim to reinforce the mechanical characteristics of gelatin hydrogel via a combination of Genipin‐based chemical cross‐linking and incorporation of the poly l‐lactic acid (PLLA) nanocylinders for application as bone scaffolds. Amine‐functionalized nanocylinders are prepared via the aminolysis procedure and incorporated in gelatin hydrogel. The nanocylinder content (0, 1, 2, 3, and 4 wt%) and cross‐linking density (0.1, 0.5, and 1 wt/vol%) are optimized to achieve suitable morphology, swelling ratio, degradation rate, and mechanical behaviors. The results indicate that hydrogel scaffold cross‐linking by 0.5 wt% of Genipin shows optimized morphological feathers with a pore size of around 300 to 500 μm as well as an average degradation rate (40.09% ± 3.08%) during 32 days. Besides, the incorporation of 3 wt% PLLA nanocylinders into the cross‐linked gelatin scaffold provides an optimized mechanical reinforcement as compressive modulus, and compressive strength show a 4‐ and 2.6‐fold increase, respectively. 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay indicates that the scaffold does not have any cytotoxicity effect. In conclusion, gelatin composite reinforced with 3 wt% PLLA nanocylinders cross‐linked via 0.5 wt/vol% Genipin is suggested as a potential scaffold for bone tissue engineering applications.
Today, despite significant progress in developing skin tissue engineering products, the fabrication of an ideal wound dressing that could meet the essential criteria, such as promoting angiogenesis -mainly in a diabetic wound- still remains a challenge. A diabetic wound is a chronic wound in which vascularization is low, and the wound healing process may stop. In this regard, Nitric oxide (NO) enhances the healing of diabetic wounds by promoting angiogenesis and providing antibacterial activity in wound sites. In this study, we produced a NO-releasing wound dressing (CMC-ALg-GSNO) composed of Carboxymethyl chitosan (CMC), sodium alginate (ALg), and Snitrosoglutathione (GSNO). The results obtained from the scanning electron microscopy (SEM) show that wound dressing has a porous structure. The water uptake and water vapor transmission for the wound dressing were obtained 4354.1 ± 179.3 % and 2753.8 ± 54.6 g/m2 per day, respectively. NO release study showed that NO release from CMC-ALg-GSNO continuously occurred within 168 hours. In vivo test, The CMC-ALg-GSNO wound dressing developed wound healing in a rat model of full-thickness diabetic wounds compared to the CMC-ALg and Gauze wound dressings. Thus, this study showed that CMC-ALg-GSNO wound dressing could lead to novel therapeutic invasions to treat diabetic wounds.
Understanding the interaction between biomaterials and
blood is
critical in the design of novel biomaterials for use in biomedical
applications. Depending on the application, biomaterials can be designed
to promote hemostasis, slow or stop bleeding in an internal or external
wound, or prevent thrombosis for use in permanent or temporary medical
implants. Bacterial nanocellulose (BNC) is a natural, biocompatible
biopolymer that has recently gained interest for its potential use
in blood-contacting biomedical applications (e.g., artificial vascular
grafts), due to its high porosity, shapeability, and tissue-like properties.
To promote hemostasis, BNC has been modified through oxidation or
functionalization with various peptides, proteins, polysaccharides,
and minerals that interact with the coagulation cascade. For use as
an artificial vascular graft or to promote vascularization, BNC has
been extensively researched, with studies investigating different
modification techniques to enhance endothelialization such as functionalizing
with adhesion peptides or extracellular matrix (ECM) proteins as well
as tuning the structural properties of BNC such as surface roughness,
pore size, and fiber size. While BNC inherently exhibits comparable
mechanical characteristics to endogenous blood vessels, these mechanical
properties can be enhanced through chemical functionalization or through
altering the fabrication method. In this review, we provide a comprehensive
overview of the various modification techniques that have been implemented
to enhance the suitability of BNC for blood-contacting biomedical
applications and different testing techniques that can be applied
to evaluate their performance. Initially, we focused on the modification
techniques that have been applied to BNC for hemostatic applications.
Subsequently, we outline the different methods used for the production
of BNC-based artificial vascular grafts and to generate vasculature
in tissue engineered constructs. This sequential organization enables
a clear and concise discussion of the various modifications of BNC
for different blood-contacting biomedical applications and highlights
the diverse and versatile nature of BNC as a natural biomaterial.
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