Development of 3D scaffolds using nanochitosan/silk-fibroin/hyaluronic acid biomaterials for tissue engineering applications

Viscoelasticity of Hyaluronic Acid Hydrogels Regulates Human Pluripotent Stem Cell-derived Spinal Cord Organoid Patterning and Vascularization

Recently, it has been recognized that natural extracellular matrix (ECM) and tissues are viscoelastic, while only elastic properties have been investigated in the past. How the viscoelastic matrix regulates stem cell patterning is critical for cell-ECM mechano-transduction. Here, this study fabricated different methacrylated hyaluronic acid (HA) hydrogels using covalent cross-linking, consisting of two gels with similar elasticity (stiffness) but different viscoelasticity, and two gels with similar viscoelasticity but different elasticity (stiffness). Meanwhile, a second set of dual network hydrogels are fabricated containing both covalent and coordinated cross-links. Human spinal cord organoid (hSCO) patterning in HA hydrogels and co-culture with isogenic human blood vessel organoids (hBVOs) are investigated. The viscoelastic hydrogels promote regional hSCO patterning compared to the elastic hydrogels. More viscoelastic hydrogels can promote dorsal marker expression, while softer hydrogels result in higher interneuron marker expression. The effects of viscoelastic properties of the hydrogels become more dominant than the stiffness effects in the co-culture of hSCOs and hBVOs. In addition, more viscoelastic hydrogels can lead to more Yes-associated protein nuclear translocation, revealing the mechanism of cell-ECM mechano-transduction. This research provides insights into viscoelastic behaviors of the hydrogels during human organoid patterning with ECM-mimicking in vitro microenvironments for applications in regenerative medicine.

Preparation and Properties of Antibacterial Silk Fibroin Scaffolds

The development of a wound dressing with both antibacterial and healing-guiding functions is a major concern in the treatment of open and infected wounds. In this study, poly(hexamethylene biguanide) hydrochloride (PHMB) was loaded into a 3D silk fibroin (SF) scaffold based on electrostatic interactions between PHMB and SF, and PHMB/SF hybrid scaffolds were prepared via freeze-drying. The effects of the PHMB/SF ratio on the antibacterial activity and cytocompatibility of the hybrid scaffold were investigated. The results of an agar disc diffusion test and a bacteriostasis rate examination showed that when the mass ratio of PHMB/SF was greater than 1/100, the scaffold exhibited obvious antibacterial activity against E. coli and S. aureus. L-929 cells were encapsulated in the PHMB/SF scaffolds and cultured in vitro. SEM, laser scanning confocal microscopy, and CCK-8 assay results demonstrated that hybrid scaffolds with a PHMB/SF ratio of less than 2/100 significantly promoted cell adhesion, spreading, and proliferation. In conclusion, a hybrid scaffold with a PHMB/SF ratio of approximately 2/100 not only effectively inhibited bacterial reproduction but also showed good cytocompatibility and is expected to be usable as a functional antibacterial dressing for wound repair.

Bioactive-Loaded Hydrogels Based on Bacterial Nanocellulose, Chitosan, and Poloxamer for Rebalancing Vaginal Microbiota

Biocompatible drug-delivery systems for soft tissue applications are of high interest for the medical and pharmaceutical fields. The subject of this research is the development of hydrogels loaded with bioactive compounds (inulin, thyme essential oil, hydro-glycero-alcoholic extract of Vitis vinifera, Opuntia ficus-indica powder, lactic acid, citric acid) in order to support the vaginal microbiota homeostasis. The nanofibrillar phyto-hydrogel systems developed using the biocompatible polymers chitosan (CS), never-dried bacterial nanocellulose (NDBNC), and Poloxamer 407 (PX) incorporated the water-soluble bioactive components in the NDBNC hydrophilic fraction and the hydrophobic components in the hydrophobic core of the PX fraction. Two NDBNC-PX hydrogels and one NDBNC-PX-CS hydrogel were structurally and physical-chemically characterized using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and rheology. The hydrogels were also evaluated in terms of thermo-responsive properties, mucoadhesion, biocompatibility, and prebiotic and antimicrobial effects. The mucin binding efficiency of hydrogel base systems was determined by the periodic acid/Schiff base (PAS) assay. Biocompatibility of hydrogel systems was determined by the MTT test using mouse fibroblasts. The prebiotic activity was determined using the probiotic strains Limosilactobacillus reuteri and Lactiplantibacillus plantarum subsp. plantarum. Antimicrobial activity was also assessed using relevant microbial strains, respectively, E. coli and C. albicans. TEM evidenced PX micelles of around 20 nm on NDBNC nanofibrils. The FTIR and XRD analyses revealed that the binary hydrogels are dominated by PX signals, and that the ternary hydrogel is dominated by CS, with additional particular fingerprints for the biocompounds and the hydrogel interaction with mucin. Rheology evidenced the gel transition temperatures of 18-22 °C for the binary hydrogels with thixotropic behavior and, respectively, no gel transition, with rheopectic behavior for the ternary hydrogel. The adhesion energies of the binary and ternary hydrogels were evaluated to be around 1.2 J/m2 and 9.1 J/m2, respectively. The hydrogels exhibited a high degree of biocompatibility, with the potential to support cell proliferation and also to promote the growth of lactobacilli. The hydrogel systems also presented significant antimicrobial and antibiofilm activity.

Current advances in anisotropic structures for enhanced osteogenesis

Bone defects are a challenge to healthcare systems, as the aging population experiences an increase in bone defects. Despite the development of biomaterials for bone fillers and scaffolds, there is still an unmet need for a bone-mimetic material. Cortical bone is highly anisotropic and displays a biological liquid crystalline (LC) arrangement, giving it exceptional mechanical properties and a distinctive microenvironment. However, the biofunctions, cell-tissue interactions, and molecular mechanisms of cortical bone anisotropic structure are not well understood. Incorporating anisotropic structures in bone-facilitated scaffolds has been recognised as essential for better outcomes. Various approaches have been used to create anisotropic micro/nanostructures, but biomimetic bone anisotropic structures are still in the early stages of development. Most scaffolds lack features at the nanoscale, and there is no comprehensive evaluation of molecular mechanisms or characterisation of calcium secretion. This manuscript provides a review of the latest development of anisotropic designs for osteogenesis and discusses current findings on cell-anisotropic structure interactions. It also emphasises the need for further research. Filling knowledge gaps will enable the fabrication of scaffolds for improved and more controllable bone regeneration.

Polysaccharide-based nanoassemblies: From synthesis methodologies and industrial applications to future prospects

Polysaccharides, due to their remarkable features, have gained significant prominence in the sustainable production of nanoparticles (NPs). High market demand and minimal production cost, compared to the chemically synthesised NPs, demonstrate a drive towards polysaccharide-based nanoparticles (PSNPs) benign to environment. Various approaches are used for the synthesis of PSNPs including cross-linking, polyelectrolyte complexation, and self-assembly. PSNPs have the potential to replace a wide diversity of chemical-based agents within the food, health, medical and pharmacy sectors. Nevertheless, the considerable challenges associated with optimising the characteristics of PSNPs to meet specific targeting applications are of utmost importance. This review provides a detailed compilation of recent accomplishments in the synthesis of PSNPs, the fundamental principles and critical factors that govern their rational fabrication, as well as various characterisation techniques. Noteworthy, the multiple use of PSNPs in different disciplines such as biomedical, cosmetics agrochemicals, energy storage, water detoxification, and food-related realms, is accounted in detail. Insights into the toxicological impacts of the PSNPs and their possible risks to human health are addressed, and efforts made in terms of PSNPs development and optimising strategies that allow for enhanced delivery are highlighted. Finally, limitations, potential drawbacks, market diffusion, economic viability and future possibilities for PSNPs to achieve widespread commercial use are also discussed.

Recent Progress in Hyaluronic-Acid-Based Hydrogels for Bone Tissue Engineering

Hydrogel-based bone tissue engineering is a potential strategy for treating bone abnormalities and fractures. Hyaluronic acid (HA) is a natural polymer that is widely distributed in the human body and plays a significant role in numerous physiological processes such as cell migration, tissue hydration, and wound healing. Hydrogels based on HA and its derivatives have gained popularity as potential treatments for bone-related diseases. HA-based hydrogels have been extensively studied for their ability to mimic the natural extracellular matrix of bone tissue and provide a suitable microenvironment for cell support and tissue regeneration. The physical and chemical properties of HA can be modified to improve its mechanical strength, biocompatibility, and osteogenic potential. Moreover, HA-based hydrogels combined with other biomaterials in the presence or absence of bioactive agents have been investigated as a means of improving the mechanical properties and bioactivity of the hydrogel scaffold. Therefore, HA-based hydrogels have shown great promise in bone tissue engineering due to their biocompatibility, osteogenic activity, and ability to mimic the natural extracellular matrix of bone tissue. Overall, this review provides a comprehensive overview of the current state of the art in HA-based hydrogels for bone tissue engineering, highlighting the key advances, challenges, and future directions in this rapidly evolving field.

Smart biomaterials and their potential applications in tissue engineering

Smart biomaterials have been rapidly advancing ever since the concept of tissue engineering was proposed. Interacting with human cells, smart biomaterials can play a key role in novel tissue morphogenesis. Various aspects of biomaterials utilized in or being sought for the goal of encouraging bone regeneration, skin graft engineering, and nerve conduits are discussed in this review. Beginning with bone, this study summarizes all the available bioceramics and materials along with their properties used singly or in conjunction with each other to create scaffolds for bone tissue engineering. A quick overview of the skin-based nanocomposite biomaterials possessing antibacterial properties for wound healing is outlined along with skin regeneration therapies using infrared radiation, electrospinning, and piezoelectricity, which aid in wound healing. Furthermore, a brief overview of bioengineered artificial skin grafts made of various natural and synthetic polymers has been presented. Finally, by examining the interactions between natural and synthetic-based biomaterials and the biological environment, their strengths and drawbacks for constructing peripheral nerve conduits are highlighted. The description of the preclinical outcome of nerve regeneration in injury healed with various natural-based conduits receives special attention. The organic and synthetic worlds collide at the interface of nanomaterials and biological systems, producing a new scientific field including nanomaterial design for tissue engineering.

A Review on Antibacterial Silk Fibroin-based Biomaterials: Current State and Prospects

Bacterial contamination of biomaterials is a common problem and a serious threat to human health worldwide. Therefore, the development of multifunctional biomaterials that possess antibacterial properties and can resist infection is a continual goal for biomedical applications. Silk fibroin (SF), approved by U.S. Food and Drug Administration (FDA) as a biomaterial, is one of the most widely studied natural polymers for biomedical applications due to its unique mechanical properties, biocompatibility, tunable biodegradation, and versatile material formats. In the last decade, many methods have been employed for the development of antibacterial SF-based biomaterials (SFBs) such as physical loading or chemical functionalization of SFBs with different antibacterial agents and bio-inspired surface modifications. In this review, we first describe the current understanding of the composition and structure-properties relationship of SF as a leading-edge biomaterial. Then we demonstrate the different antibacterial agents and methods implemented for the development of bactericidal SFBs, their mechanisms of action, and different applications. We briefly address their fabrication methods, advantages, and limitations, and finally discuss the emerging technologies and future trends in this research area.

The Application of Chitosan Nanostructures in Stomatology

Chitosan (CS) is a natural polymer with a positive charge, a deacetylated derivative of chitin. Chitosan nanostructures (nano-CS) have received increasing interest due to their potential applications and remarkable properties. They offer advantages in stomatology due to their excellent biocompatibility, their antibacterial properties, and their biodegradability. Nano-CSs can be applied as drug carriers for soft tissue diseases, bone tissue engineering and dental hard tissue remineralization; furthermore, they have been used in endodontics due to their antibacterial properties; and, finally, nano-CS can improve the adhesion and mechanical properties of dental-restorative materials due to their physical blend and chemical combinations. In this review, recent developments in the application of nano-CS for stomatology are summarized, with an emphasis on nano-CS’s performance characteristics in different application fields. Moreover, the challenges posed by and the future trends in its application are assessed.

Preparation, characterization, and antibacterial properties of hybrid nanofibrous scaffolds for cutaneous tissue engineering

Since polymeric nanofibrous scaffolds have been widely used in tissue regeneration, the risk of bacterial infections should not be neglected. In the present work, poly-caprolactone-silk fibroin-soluble eggshell membrane-silver nanoparticles (PCL-SF-SESM-AgNPs) and caprolactone-silk fibroin-soluble eggshell membrane-chitosan (PCL-SF-SESM-CS) scaffolds were fabricated via the electrospinning method for cutaneous regeneration. The composition, morphology, hydrophilicity, and mechanical features of prepared scaffolds were evaluated using Fourier transform infrared (FT-IR), scanning electron microscope (SEM), tensile, and water contact angle tests. The existence of AgNPs in PCL/SF/SESM/AgNPs nanofibers was confirmed by UV-visible, Transmission electron microscopes (TEM), and X-Ray Diffraction (XRD) patterns. Besides, cell adhesion, proliferation, and differentiation process of cutaneous progenitor cells, namely basal cell carcinoma (BCCs), toward keratinocyte-like cells were evaluated using MTT analysis, DAPI, Immunofluorescence imaging (IF), and Real-Time Quantitative Reverse Transcription PCR (QRT-PCR) assay. The results indicated that prepared nanofibrous mats are appropriate candidates for cutaneous regeneration and in advanced in vivo applications could be used. Lastly, the antimicrobial potential of prepared nanofibers against microorganisms such as E. coli, S. aureus, and C. Albicans was analyzed using the disc diffusion method. Results revealed that chitosan-containing nanofibrous scaffolds indicate inhibition against S. aureus, but PCL-SF-SESM as control group not. In addition, against C. albicans any antifungal activity was not observed.

Preparation and biological properties of silk fibroin/nano-hydroxyapatite/hyaluronic acid composite scaffold

In this study, the silk fibroin/nano-hydroxyapatite/hyaluronic acid (SF/nHAp/HA) composite scaffolds with different HA contents were developed by blending, cross-linking and freeze-drying, and their physicochemical properties and cell biocompatibilityin vitrowere subsequently studied. It was observed that the molecular conformation of the composite scaffolds was mainly composed of silk I and a small amount of theβ-sheets structure. On enhancing the HA content, the pore size of the scaffold decreased, while the porosity, water absorption, swelling ratio and mechanical properties were observed to increase. In particular, the SF/nHAp/HA scaffold with a 5.0 wt% ratio exhibited the highest water absorption and mechanical properties among the developed materials. In addition, thein vitrocytocompatibility analysis showed that the bone marrow mesenchymal stem cells exhibited excellent cell proliferation and osteogenic differentiation ability on the SF/nHAp/5.0 wt%HA scaffolds, as compared with the other scaffolds. It can be concluded that the developed composite scaffolds represent a promising class of materials for the bone tissue repair and regeneration.

Applications of bacteria and their derived biomaterials for repair and tissue regeneration

Microorganisms such as bacteria and their derived biopolymers can be used in biomaterials and tissue regeneration. Various methods have been applied to regenerate damaged tissues, but using probiotics and biomaterials derived from bacteria with improved economic-production efficiency and highly applicable properties can be a new solution in tissue regeneration. Bacteria can synthesize numerous types of biopolymers. These biopolymers possess many desirable properties such as biocompatibility and biodegradability, making them good candidates for tissue regeneration. Here, we reviewed different types of bacterial-derived biopolymers and highlight their applications for tissue regeneration.

How to Improve Physico-Chemical Properties of Silk Fibroin Materials for Biomedical Applications?-Blending and Cross-Linking of Silk Fibroin-A Review

This review supplies a report on fresh advances in the field of silk fibroin (SF) biopolymer and its blends with biopolymers as new biomaterials. The review also includes a subsection about silk fibroin mixtures with synthetic polymers. Silk fibroin is commonly used to receive biomaterials. However, the materials based on pure polymer present low mechanical parameters, and high enzymatic degradation rate. These properties can be problematic for tissue engineering applications. An increased interest in two- and three-component mixtures and chemically cross-linked materials has been observed due to their improved physico-chemical properties. These materials can be attractive and desirable for both academic, and, industrial attention because they expose improvements in properties required in the biomedical field. The structure, forms, methods of preparation, and some physico-chemical properties of silk fibroin are discussed in this review. Detailed examples are also given from scientific reports and practical experiments. The most common biopolymers: collagen (Coll), chitosan (CTS), alginate (AL), and hyaluronic acid (HA) are discussed as components of silk fibroin-based mixtures. Examples of binary and ternary mixtures, composites with the addition of magnetic particles, hydroxyapatite or titanium dioxide are also included and given. Additionally, the advantages and disadvantages of chemical, physical, and enzymatic cross-linking were demonstrated.

Fabrication of nanochitosan incorporated polypyrrole/alginate conducting scaffold for neural tissue engineering

The utilization of conductive polymers for fabrication of neural scaffolds have attracted much interest because of providing a microenvironment which can imitate nerve tissues. In this study, polypyrrole (PPy)-alginate (Alg) composites were prepared using different percentages of alginate and pyrrole by oxidative polymerization method using FeCl3 as an oxidant and electrical conductivity of composites were measured by four probe method. In addition, chitosan-based nanoparticles were synthesized by ionic gelation method and after characterization merged into PPy-Alg composite in order to fabricate a conductive, hydrophilic, processable and stable scaffold. Physiochemical characterization of nanochitosan/PPy-Alg scaffold such as electrical conductivity, porosity, swelling and degradation was investigated. Moreover, cytotoxicity and proliferation were examined by culturing OLN-93 neural and human dermal fibroblasts cells on the Nanochitosan/PPy-Alg scaffold. Due to the high conductivity, the film with ratio 2:10 (PPy-Alg) was recognized more suitable for fabrication of the final scaffold. Results from FT-IR and SEM, evaluation of porosity, swelling and degradation, as well as viability and proliferation of OLN-93 neural and fibroblast cells confirmed cytocompatiblity of the Nanochitosan/PPy-Alg scaffold. Based on the features of the constructed scaffold, Nanochitosan/PPy-Alg scaffold can be a proper candidate for neural tissue engineering.

Stem Cell-Friendly Scaffold Biomaterials: Applications for Bone Tissue Engineering and Regenerative Medicine

Bone is a dynamic organ with high regenerative potential and provides essential biological functions in the body, such as providing body mobility and protection of internal organs, regulating hematopoietic cell homeostasis, and serving as important mineral reservoir. Bone defects, which can be caused by trauma, cancer and bone disorders, pose formidable public health burdens. Even though autologous bone grafts, allografts, or xenografts have been used clinically, repairing large bone defects remains as a significant clinical challenge. Bone tissue engineering (BTE) emerged as a promising solution to overcome the limitations of autografts and allografts. Ideal bone tissue engineering is to induce bone regeneration through the synergistic integration of biomaterial scaffolds, bone progenitor cells, and bone-forming factors. Successful stem cell-based BTE requires a combination of abundant mesenchymal progenitors with osteogenic potential, suitable biofactors to drive osteogenic differentiation, and cell-friendly scaffold biomaterials. Thus, the crux of BTE lies within the use of cell-friendly biomaterials as scaffolds to overcome extensive bone defects. In this review, we focus on the biocompatibility and cell-friendly features of commonly used scaffold materials, including inorganic compound-based ceramics, natural polymers, synthetic polymers, decellularized extracellular matrix, and in many cases, composite scaffolds using the above existing biomaterials. It is conceivable that combinations of bioactive materials, progenitor cells, growth factors, functionalization techniques, and biomimetic scaffold designs, along with 3D bioprinting technology, will unleash a new era of complex BTE scaffolds tailored to patient-specific applications.

Biopolymeric, Nanopatterned, Fibrous Carriers for Wound Healing Applications

Background:

Any sort of wound injury leads to skin integrity and further leads to wound formation. Millions of deaths are reported every year, which contributes to an economical hamper world widely, this accounts for 10% of death rate that insight into various diseases.

Current Methodology:

Rapid wound healing plays an important role in effective health care. Wound healing is a multi-factorial physiological process, which helps in the growth of new tissue to render the body with the imperative barrier from the external environment. The complexity of this phenomenon makes it prone to several abnormalities. Wound healing, as a normal biological inherent process occurs in the body, which is reaped through four highly defined programmed phases, such as hemostasis, inflammation, proliferation, and remodeling and these phases occur in the proper progression. An overview, types, and classification of wounds along with the stages of wound healing and various factors affecting wound healing have been discussed systematically. Various biopolymers are reported for developing nanofibers and microfibers in wound healing, which can be used as a therapeutic drug delivery for wound healing applications. Biopolymers are relevant for biomedical purposes owing to biodegradability, biocompatibility, and non- toxicity. Biopolymers such as polysaccharides, proteins and various gums are used for wound healing applications. Patents and future perspectives have been given in the concluding part of the manuscript. Overall, applications of biopolymers in the development of fibers and their applications in wound healing are gaining interest in researchers to develop modified biopolymers and tunable delivery systems for effective management and care of different types of wounds.

Characterization and antimicrobial effect of a bioinspired thymol coating formed on titanium surface by one-step immersion treatment

OBJECTIVE

To develop an antimicrobial and anti-adherent thymol (TOH)-containing coating on titanium (Ti) by a bioinspired one-step biocompatible method.

METHODS

A nanolayer of adsorbed TOH (TOH-NL-Ti) was formed by an easy deep coating method on Ti surface. The treatment consists in a simple one-step immersion process in a TOH-containing solution. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR), potentiodynamic electrochemical technique, open circuit potential records, Atomic Force Microscopy (AFM) and measurements of TOH release were used to characterize TOH-NL-Ti. Live/Dead staining and plate counting were employed to quantify attached and living adhered bacteria, respectively. Biocompatibility and cytotoxicity in fibroblastic and pre-osteoblastic cell lines were evaluated by acridine orange staining and MTT assay, respectively.

RESULTS

TOH adsorbed on TOH-NL-Ti was detected by ATR-FTIR and electrochemical techniques. ATR-FTIR results showed that TOH nanofilms development involves spontaneous production of ketonic structures on Ti surface. AFM analysis revealed that the thickness of the TOH-NL was below 80 nm. Finally, microbiological assays confirmed that TOH-NL-Ti can inhibit the adhesion and kill attached bacteria leading to the eradication of leaving cells on its surface. After 24 h of biocidal release, the antimicrobial effect is also significant (a decrease of 3 orders in the number of attached bacteria).

SIGNIFICANCE

The formation of TOH-NL-Ti nanolayer is a simple strategy able to be applied by not specially trained personnel, to reduce implant infection risks, ensure highly effective antimicrobial action and inhibition of bacterial adhesion on Ti surfaces without showing toxic effects for pre-osteoblastic and fibroblastic cells.

Crosslinked Hyaluronic Acid Gels with Blood-Derived Protein Components for Soft Tissue Regeneration

Hyaluronic acid (HA) is an ideal initial material for preparing hydrogels, which may be used as scaffolds in soft tissue engineering based on their advantageous physical and biological properties. In this study, two crosslinking agents, divinyl sulfone (DVS) and butanediol diglycidyl ether, were used to investigate their effect on the properties of HA hydrogels. As HA hydrogels alone do not promote cell adhesion on the scaffold, fibrin and serum from platelet-rich fibrin (SPRF) were combined with the scaffold; the aim was to create a material intended to be used as soft tissue implant that facilitates new tissue formation, and degrades over time. The chemical changes were characterized and cell attachment capacity of the protein-containing gels was examined using human mesenchymal stem cells, and viability was assessed using live-dead staining. Fourier-transform infrared measurements revealed that linking fibrin into the gel was more effective than linking SPRF. The scaffolds were found to be able to support cell adherence onto the hydrogels, and the best result was achieved when HA was crosslinked with DVS and contained fibrin. The most promising derivative, 5% DVS-crosslinked fibrin-containing hydrogel, was injected subcutaneously into C57BL/6 mice for 12 weeks. The scaffold was proven to be biocompatible, remodeling, and vascularization occurred, while shape and integrity were maintained. Impact statement Fibrin was combined with crosslinked hyaluronic acid (HA) for regenerative application, the structure of the combination of crosslinked HA with blood-derived protein was analyzed and effective coating was proven. It was observed that the fibrin content led to better mesenchymal stem cell attachment in vitro. The compositions showed biocompatibility, connective tissue and vascularization took place when implanted in vivo. Thus, a biocompatible, injectable gel was produced, which is a potential candidate for soft tissue implantation.

Glycosaminoglycan-Inspired Biomaterials for the Development of Bioactive Hydrogel Networks

Glycosaminoglycans (GAG) are long, linear polysaccharides that display a wide range of relevant biological roles. Particularly, in the extracellular matrix (ECM) GAG specifically interact with other biological molecules, such as growth factors, protecting them from proteolysis or inhibiting factors. Additionally, ECM GAG are partially responsible for the mechanical stability of tissues due to their capacity to retain high amounts of water, enabling hydration of the ECM and rendering it resistant to compressive forces. In this review, the use of GAG for developing hydrogel networks with improved biological activity and/or mechanical properties is discussed. Greater focus is given to strategies involving the production of hydrogels that are composed of GAG alone or in combination with other materials. Additionally, approaches used to introduce GAG-inspired features in biomaterials of different sources will also be presented.

A novel egg-shell membrane based hybrid nanofibrous scaffold for cutaneous tissue engineering

Background

The main issue in cutaneous regeneration is to develop engineered scaffolds based on natural extracellular matrix to promote dynamics of skin progenitor cells and accelerate differentiation into mature keratinocytes.

Methods

In this study, nanofibrous scaffolds composed of a blend poly (ɛ-caprolactone) (PCL), silk fibroin (SF), soluble eggshell membrane (SESM), and Aloe vera (AV) gel were developed by electrospinning method and human basal cells were used to examine differentiation capacity toward keratinocyte-like cells. For this propose, cells were allocated to four distinct groups; control, PCL/SF, PCL/SF/SESM, and PCL/SF/SESM/AV. In all groups, cells were incubated with differentiation medium. Morphology, composition, hydrophilicity and mechanical features of PCL/SF, PCL/SF/SESM and PCL/SF/SESM/AV nanofibers were studied by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), water contact angle and tensile tests. To examine the orientation of basal cells to mature keratinocytes, we performed immunofluorescence analysis by monitoring cytokeratin-19. The expression of genes such as involucrin, keratin-14 and -5 was monitored by real-time PCR assay.

Results

PCL/SF, PCL/SF/SESM, and PCL/SF/SESM/AV had suitable physic chemical indices and biological activities to be applied as biomimetic scaffolds for the restoration cutaneous tissue. Compared to control, we found an increased basal cell proliferation at 7 and 14 days after plating on scaffolds and reach maximum levels in group PCL/SF/SESM/AV on day 14 (p < 0.05). Electron microscopy showed cell flattening, morphological adaptation. An integrated cell-to-cell connection was generated after cell seeding on scaffolds in all groups. Immunofluorescence imaging showed the ability of basal cells to synthesize cytokeratin-19 in PCL/SF, PCL/SF/SESM, and positive control cells after exposure to differentiation medium. However, these values were less in PCL/SF/SESM/AV compared to other groups. Real-time PCR analysis showed the potency of all scaffolds to induce the transcription of involucrin, keratin-14 and -5, especially involucrin in PCL/SF/SESM/AV group compared to the negative control.

Conclusion

Modulation of scaffolds with natural biopolymers could enable us to synthesize structures appropriate for cutaneous regeneration.

Biomaterials for bone tissue engineering scaffolds: a review

Bone tissue engineering has been continuously developing since the concept of "tissue engineering" has been proposed. Biomaterials that are used as the basic material for the fabrication of scaffolds play a vital role in bone tissue engineering. This paper first introduces a strategy for literature search. Then, it describes the structure, mechanical properties and materials of natural bone and the strategies of bone tissue engineering. Particularly, it focuses on the current knowledge about biomaterials used in the fabrication of bone tissue engineering scaffolds, which includes the history, types, properties and applications of biomaterials. The effects of additives such as signaling molecules, stem cells, and functional materials on the performance of the scaffolds are also discussed.

An injectable silk fibroin nanofiber hydrogel hybrid system for tumor upconversion luminescence imaging and photothermal therapy

In this paper, we developed a silk fibroin nanofiber (SF) hydrogel system complexed with upconversion nanoparticles and nano-graphene oxide (SF/UCNP@NGO) for upconversion luminescence imaging and photothermal therapy.