Herbal Remedies as Potential in Cartilage Tissue Engineering: An Overview of New Therapeutic Approaches and Strategies.

It is estimated that by 2023, approximately 20% of the population of Western Europe and North America will suffer from a degenerative joint disease commonly known as osteoarthritis (OA). During the development of OA, pro-inflammatory cytokines are one of the major causes that drive the production of inflammatory mediators and thus of matrix-degrading enzymes. OA is a challenging disease for doctors due to the limitation of the joint cartilage's capacity to repair itself. Though new treatment approaches, in particular with mesenchymal stem cells (MSCs) that integrate the tissue engineering (TE) of cartilage tissue, are promising, they are not only expensive but more often do not lead to the regeneration of joint cartilage. Therefore, there is an increasing need for novel, safe, and more effective alternatives to promote cartilage joint regeneration and TE. Indeed, naturally occurring phytochemical compounds (herbal remedies) have a great anti-inflammatory, anti-oxidant, and anabolic potential, and they have received much attention for the development of new therapeutic strategies for the treatment of inflammatory diseases, including the prevention of age-related OA and cartilage TE. This paper summarizes recent research on herbal remedies and their chondroinductive and chondroprotective effects on cartilage and progenitor cells, and it also emphasizes the possibilities that exist in this research area, especially with regard to the nutritional support of cartilage regeneration and TE, which may not benefit from non-steroidal anti-inflammatory drugs (NSAIDs).

Evaluation of the effects of nano-TiO2 on bioactivity and mechanical properties of nano bioglass-P3HB composite scaffold for bone tissue engineering.

To emulate bone structure, porous composite scaffold with suitable mechanical properties should be designed. In this research the effects of nano-titania (nTiO2) on the bioactivity and mechanical properties of nano-bioglass-poly-3-hydroxybutyrate (nBG/P3HB)-composite scaffold were evaluated. First, nBG powder was prepared by melting method of pure raw materials at a temperature of 1400 °C and then the porous ceramic scaffold of nBG/nTiO2 with 30 wt% of nBG containing different weight ratios of nTiO2 (3, 6, and 9 wt% of nTiO2 with grain size of 35-37 nm) was prepared by using polyurethane sponge replication method. Then the scaffolds were coated with P3HB in order to increase the scaffold's mechanical properties. Mechanical strength and modulus of scaffolds were improved by adding nTiO2 to nBG scaffold and adding P3HB to nBG/nTiO2 composite scaffold. The results of the compressive strength and porosity tests showed that the best scaffold is 30 wt% of nBG with 6 wt% of nTiO2 composite scaffold immersed for 30 s in P3HB with 79.5-80 % of porosity in 200-600 µm, with a compressive strength of 0.15 MPa and a compressive modulus of 30 MPa, which is a good candidate for bone tissue engineering. To evaluate the bioactivity of the scaffold, the simulated body fluid (SBF) solution was used. The best scaffold with 30 wt% of nBG, 6 wt% of P3HB and 6 wt% of nTiO2 was immersed in SBF for 4 weeks at an incubation temperature of 37 °C. The bioactivity of the scaffolds was characterized by AAS, SEM, EDXA and XRD. The results of bioactivity showed that bone-like apatite layer formed well at scaffold surface and adding nTiO2 to nBG/P3HB composite scaffold helped increase the bioactivity rate.

Evaluation of mechanical property and bioactivity of nano-bioglass 45S5 scaffold coated with poly-3-hydroxybutyrate.

One of the major challenges facing researchers of tissue engineering is scaffold design with desirable physical and mechanical properties for growth and proliferation of cells and tissue formation. In this research, firstly, nano-bioglass powder with grain sizes of 55-56 nm was prepared by melting method of industrial raw materials at 1,400 °C. Then the porous ceramic scaffold of bioglass with 30, 40 and 50 wt% was prepared by using the polyurethane sponge replication method. The scaffolds were coated with poly-3-hydroxybutyrate (P3HB) for 30 s and 1 min in order to increase the scaffold's mechanical properties. XRD, XRF, SEM, FE-SEM and FT-IR were used for phase and component studies, morphology, particle size and determination of functional groups, respectively. XRD and XRF results showed that the type of the produced bioglass was 45S5. The results of XRD and FT-IR showed that the best temperature to produce bioglass scaffold was 600 °C, in which Na2Ca2Si3O9 crystal is obtained. By coating the scaffolds with P3HB, a composite scaffold with optimal porosity of 80-87% in 200-600 µm and compression strength of 0.1-0.53 MPa was obtained. According to the results of compressive strength and porosity tests, the best kind of scaffold was produced with 30 wt% of bioglass immersed for 1 min in P3HB. To evaluate the bioactivity of the scaffold, the SBF solution was used. The selected scaffold (30 wt% bioglass/6 wt% P3HB) was maintained for up to 4 weeks in this solution at an incubation temperature of 37 °C. The XRD, SEM EDXA and AAS tests were indicative of hydroxyapatite formation on the surface of bioactive scaffold. This scaffold has some potential to use in bone tissue engineering.

Keratin-containing scaffolds for tissue engineering applications: a review.

In tissue engineering and regenerative medicine applications, the utilization of bioactive materials has become a routine tool. The goal of tissue engineering is to create new organs and tissues by combining cell biology, materials science, reactor engineering, and clinical research. As part of the growth pattern for primary cells in an organ, backing material is frequently used as a supporting material. A porous three-dimensional (3D) scaffold can provide cells with optimal conditions for proliferating, migrating, differentiating, and functioning as a framework. Optimizing the scaffolds' structure and altering their surface may improve cell adhesion and proliferation. A keratin-based biomaterials platform has been developed as a result of discoveries made over the past century in the extraction, purification, and characterization of keratin proteins from hair and wool fibers. Biocompatibility, biodegradability, intrinsic biological activity, and cellular binding motifs make keratin an attractive biomaterial for tissue engineering scaffolds. Scaffolds for tissue engineering have been developed from extracted keratin proteins because of their capacity to self-assemble and polymerize into intricate 3D structures. In this review article, applications of keratin-based scaffolds in different tissues including bone, skin, nerve, and vascular are explained based on common methods of fabrication such as electrospinning, freeze-drying process, and sponge replication method.

Ultra-thin electrospun nanocomposite scaffold of poly (3-hydroxybutyrate)-chitosan/magnetic mesoporous bioactive glasses for bone tissue engineering applications.

Bioglass is widely used in skeletal tissue engineering due to its outstanding bioactive properties. In the present study, magnetic mesoporous bioglass (MMBG) synthesized through the sol-gel method was incorporated into poly(3-hydroxybutyrate)-chitosan (PHB-Cs) solution and the resulting electrospun nanocomposite scaffolds were investigated and compared with MMBG free scaffold. The addition of 10 wt% MMBG has an outstanding effect on producing ultra-thin electrospun nanocomposite fibers due to its magnetic content (diameter of ≃128 nm). This improvement led to better mechanical properties, including an increase in both tensile modulus (up to ≃229 MPa) and tensile strength (to ≃4.95 MPa). Although the inclusion of MMBG slightly decreased the surface roughness of the nanofibrous scaffold (RMS from ≃197 to 154 nm), it could improve the wettability (WCA from ≃54 to 44°). This achievement has the potential to bring an enhancement in biomineralization and biological response. These outputs, combined with the observed increase in human osteoblast MG-63 cell viability (≃53 % improvement) as measured by MTT assay, DAPI, and SEM indicate prefer cell behavior of this nanocomposite structure. Additionally, the qualitative improvement in Alizarin Red staining and the quantitative enhancement of ALP secretion, serve as further evidence of the PHB-Cs/MMBG ultrathin nanofibers potential in bone tissue engineering.

Chitosan/MWCNTs nanocomposite coating on 3D printed scaffold of poly 3-hydroxybutyrate/magnetic mesoporous bioactive glass: A new approach for bone regeneration.

The utilization of 3D printing has become increasingly common in the construction of composite scaffolds. In this study, magnetic mesoporous bioactive glass (MMBG) was incorporated into polyhydroxybutyrate (PHB) to construct extrusion-based 3D printed scaffold. After fabrication of the PHB/MMBG composite scaffolds, they were coated with chitosan (Cs) and chitosan/multi-walled carbon nanotubes (Cs/MWCNTs) solutions utilizing deep coating method. FTIR was conducted to confirm the presence of Cs and MWCNTs on the scaffolds' surface. The findings of mechanical analysis illustrated that presence of Cs/MWCNTs on the composite scaffolds increases compressive young modulus significantly, from 16.5 to 42.2 MPa. According to hydrophilicity evaluation, not only MMBG led to decrease the contact angle of pure PHB but also scaffolds surface modification utilization of Cs and MWCNTs, the contact angle decreased significantly from 82.34° to 54.15°. Furthermore, investigation of cell viability, cell metabolism and inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) and interleukin-10 (IL-10) and transforming growth factor-beta (TGF-ß) proved that the scaffolds not only do not stimulate the immune system, but also polarize macrophage cells from M1 phase to M2 phase. The present study highlights the suitability of 3D printed scaffold PHB/MMBG with Cs/MWCNTs coating for bone tissue engineering.

Evaluating the osteogenic properties of polyhydroxybutyrate-zein/multiwalled carbon nanotubes (MWCNTs) electrospun composite scaffold for bone tissue engineering applications.

In this investigation, the electrospun nanocomposite scaffolds were developed utilizing poly-3-hydroxybutyrate (PHB), zein, and multiwalled carbon nanotubes (MWCNTs) at varying concentrations of MWCNTs including 0.5 and 1 wt%. Based on the SEM evaluations, the scaffold containing 1 wt% MWCNTs (PZ-1C) exhibited the lowest fiber diameter (384 ± 99 nm) alongside a suitable porosity percentage. The presence of zein and MWCNT in the chemical structure of the scaffold was evaluated by FTIR. Furthermore, TEM images revealed the alignment of MWCNTs with the fibers. Adding 1 % MWCNTs to the PHB-zein scaffold significantly enhanced tensile strength by about 69 % and reduced elongation by about 31 %. Hydrophilicity, surface roughness, crystallinity, and biomineralization were increased by incorporating 1 wt% MWCNTs, while weight loss after in vitro degradation was decreased. The MG-63 cells exhibited enhanced attachment, viability, ALP secretion, calcium deposition, and gene expression (COLI, RUNX2, and OCN) when cultivated on the scaffold containing MWCNTs compared to the scaffolds lacking MWCNTs. Moreover, the study found that MWCNTs significantly reduced platelet adhesion and hemolysis rates below 4 %, indicating their favorable anti-hemolysis properties. Regarding the aforementioned results, the PZ-1C electrospun composite scaffold is a promising scaffold with osteogenic properties for bone tissue engineering applications.

Evaluation of the effects of decellularized extracellular matrix nanoparticles incorporation on the polyhydroxybutyrate/nano chitosan electrospun scaffold for cartilage tissue engineering.

Recent research focuses on fabricating scaffolds imitating the extracellular matrix (ECM) in texture, composition, and functionality. Moreover, specific nano-bio-particles can enhance cell differentiation. Decellularized ECM nanoparticles possess all of the mentioned properties. In this research, cartilage ECM, extracted from the cow's femur condyle, was decellularized, and ECM nanoparticles were synthesized. Finally, nanocomposite electrospun fibers containing polyhydroxybutyrate (PHB), chitosan (Cs) nanoparticles, and ECM nanoparticles were fabricated and characterized. TEM and DLS results revealed ECM nanoparticle sizes of 17.51 and 21.6 nm, respectively. Optimal performance was observed in the scaffold with 0.75 wt% ECM nanoparticles (PHB-Cs/0.75E). By adding 0.75 wt% ECM, the ultimate tensile strength and elongation at break increased by about 29 % and 21 %, respectively, while the water contact angle and crystallinity decreased by about 36° and 2 %, respectively. Uneven and rougher surfaces of the PHB-Cs/0.75E were determined by FESEM and AFM images, respectively. TEM images verified the uniform dispersion of nanoparticles within the fibers. After 70 days of degradation in PBS, the PHB-Cs/0.75E and PHB-Cs scaffolds demonstrated insignificant weight loss differences. Eventually, enhanced viability, attachment, and proliferation of the human costal chondrocytes on the PHB-Cs/0.75E scaffold, concluded from MTT, SEM, and DAPI staining, confirmed its potential for cartilage tissue engineering.

Chondrogenesis of mesenchymal stromal cells on the 3D printed polycaprolactone/fibrin/decellular cartilage matrix hybrid scaffolds in the presence of piascledine.

Nowadays, cartilage tissue engineering (CTE) is considered important due to lack of repair of cartilaginous lesions and the absence of appropriate methods for treatment. In this study, polycaprolactone (PCL) scaffolds were fabricated by three-dimensional (3D) printing and were then coated with fibrin (F) and acellular solubilized extracellular matrix (ECM). After extracting adipose-derived stem cells (ADSCs), 3D-printed scaffolds were characterized and compared to hydrogel groups. After inducing the chondrogenic differentiation in the presence of Piascledine and comparing it with TGF-ß3 for 28 days, the expression of genes involved in chondrogenesis (AGG, COLII) and the expression of the hypertrophic gene (COLX) were examined by real-time PCR. The expression of proteins COLII and COLX was also determined by immunohistochemistry. Glycosaminoglycan was measured by toluidine blue staining. 3D-printed scaffolds clearly improved cell proliferation, viability, water absorption and compressive strength compared to the hydrogel groups. Moreover, the use of compounds such as ECM and Piascledine in the process of ADSCs chondrogenesis induction increased cartilage-specific markers and decreased the hypertrophic marker compared to TGF-ß3. In Piascledine groups, the expression of COLL II protein, COLL II and Aggrecan genes, and the amount of glycosaminoglycan showed a significant increase in the PCL/F/ECM compared to the PCL and PCL/F groups.

Smart co-delivery of plasmid DNA and doxorubicin using MCM-chitosan-PEG polymerization functionalized with MUC-1 aptamer against breast cancer.

This study introduces an innovative co-delivery approach using the MCM-co-polymerized nanosystem, integrating chitosan and polyethylene glycol, and targeted by the MUC-1 aptamer (MCM@CS@PEG-APT). This system enables simultaneous delivery of the GFP plasmid and doxorubicin (DOX). The synthesis of the nanosystem was thoroughly characterized at each step, including FTIR, XRD, BET, DLS, FE-SEM, and HRTEM analyses. The impact of individual polymers (chitosan and PEG) on payload retardation was compared to the co-polymerized MCM@CS@PEG conjugation. Furthermore, the DOX release mechanism was investigated using various kinetic models. The nanosystem's potential for delivering GFP plasmid and DOX separately and simultaneously was assessed through fluorescence microscopy and flow cytometry. The co-polymerized nanosystem exhibited superior payload entrapment (1:100 ratio of Plasmid:NPs) compared to separately polymer-coated counterparts (1:640 ratio of Plasmid:NPs). Besides, the presence of pH-sensitive chitosan creates a smart nanosystem for efficient DOX and GFP plasmid delivery into tumor cells, along with a Higuchi model pattern for drug release. Toxicity assessments against breast tumor cells also indicated reduced off-target effects compared to pure DOX, introducing it as a promising candidate for targeted cancer therapy. Cellular uptake findings demonstrated the nanosystem's ability to deliver GFP plasmid and DOX separately into MCF-7 cells, with rates of 32% and 98%, respectively. Flow cytometry results confirmed efficient co-delivery, with 42.7% of cells showing the presence of both GFP-plasmid and DOX, while 52.2% exclusively contained DOX. Overall, our study explores the co-delivery potential of the MCM@CS@PEG-APT nanosystem in breast cancer therapy. This system's ability to co-deliver multiple agents preciselyopens new avenues for targeted therapeutic strategies.

Graphene oxide-encapsulated baghdadite nanocomposite improved physical, mechanical, and biological properties of a vancomycin-loaded PMMA bone cement.

Polymethyl methacrylate (PMMA) bone cement is commonly used in orthopedic surgeries to fill the bone defects or fix the prostheses. These cements are usually containing amounts of a nonbioactive radiopacifying agent such as barium sulfate and zirconium dioxide, which does not have a good interface compatibility with PMMA, and the clumps formed from these materials can scratch metal counterfaces. In this work, graphene oxide encapsulated baghdadite (GOBgh) nanoparticles were applied as radiopacifying and bioactive agent in a PMMA bone cement containing 2 wt.% of vancomycin (VAN). The addition of 20 wt.% of GOBgh (GOBgh20) nanoparticles to PMMA powder caused a 33.6% increase in compressive strength and a 70.9% increase in elastic modulus compared to the Simplex® P bone cement, and also enhanced the setting properties, radiopacity, antibacterial activity, and the apatite formation in simulated body fluid. In vitro cell assessments confirmed the increase in adhesion and proliferation of MG-63 cells as well as the osteogenic differentiation of human adipose-derived mesenchymal stem cells on the surface of PMMA-GOBgh20 cement. The chorioallantoic membrane assay revealed the excellent angiogenesis activity of nanocomposite cement samples. In vivo experiments on a rat model also demonstrated the mineralization and bone integration of PMMA-GOBgh20 cement within four weeks. Based on the promising results obtained, PMMA-GOBgh20 bone cement is suggested as an optimal sample for use in orthopedic surgeries.

Mechanical evaluation of nHAp scaffold coated with poly-3-hydroxybutyrate for bone tissue engineering.

Regeneration of bone, cartilage and osteochondral tissues by tissue engineering has attracted intense attention due to its potential advantages over the traditional replacement of tissues with synthetic implants. Nevertheless, there is still a dearth of ideal or suitable scaffolds based on porous biomaterials, and the present study was undertaken to develop and evaluate a useful porous composite scaffold system. In this study, nano hydroxyapatite (nHAp) powder made (about 35-45 nm) by heating at temperature of 900 degrees C and porous hydroxyapatite (40, 50 and 60 wt% solution) for making scaffold, by using Polyurethane sponge replication method. In order to increase the scaffolds mechanical properties, they coated with 2, 4 and 6 wt% Poly-3-hydroxybutyrate (P3HB) for 30 sec and 60 sec, respectively; after the scaffold coated by Polymer and survey results, this scaffold is nHAp/P3HB composite. Based on these results, this scaffold is an optimized one among three tested above mentioned composition and can be utilized in bone tissue engineering. In the result, the best of scaffold is with 50 wt% HAp and 6 wt% P3HB and porosity of present is between 80-90% with compressive strength and modulus 1.51 MPa and 22.73 MPa, respectively, that it can be application in bone tissue engineering.

Evaluation of the effects of halloysite nanotube on polyhydroxybutyrate - chitosan electrospun scaffolds for cartilage tissue engineering applications.

Scaffolding method and material that mimic the extracellular matrix (ECM) of host tissue is an integral part of cartilage tissue engineering. This study aims to enhance the properties of electrospun scaffolds made of polyhydroxybutyrate (PHB) - Chitosan (Cs) by adding 1, 3, and 5 wt% halloysite nanotubes (HNT). The morphological, mechanical, and hydrophilicity evaluations expressed that the scaffold containing 3 wt% HNT exhibits the most appropriate features. The FTIR and Raman analysis confirmed hydrogen bond formation between the HNT and PHB-Cs blend. 3 wt% of HNT incorporation decreased the mean fibers' diameter from 965.189 to 745.16 nm and enhanced tensile strength by 169.4 %. By the addition of 3 wt% HNT, surface contact angle decreased from 61.45° ± 3.3 to 46.65 ± 1.8° and surface roughness increased from 684.69 to 747.62 nm. Our findings indicated that biodegradation had been slowed by incorporating HNT into the PHB-Cs matrix. Also, MTT test results demonstrated a significant increase in cell viability of chondrocytes on the PHB-Cs/3 wt% HNT (PC-3H) scaffold after 7 days of cell culture. Accordingly, the PC-3H scaffold can be considered a potential candidate for cartilage tissue engineering.

Investigation of physical, mechanical and biological properties of polyhydroxybutyrate-chitosan/graphene oxide nanocomposite scaffolds for bone tissue engineering applications.

Mechanical properties appropriate to native tissues, as an essential component in bone tissue engineering scaffolds, plays a significant role in tissue formation. In the current study, Poly-3 hydroxybutyrate-chitosan (PC) scaffolds reinforced with graphene oxide (GO) were made by the electrospinning method. The addition of GO led to a decrease in fibers diameter, an increase in thermal capacity and an improvement in the surface hydrophilicity of nanocomposite scaffolds. A significant increase in the mechanical properties of PC/GO (PCG) nanocomposite scaffolds was achieved due to the inherent strength of GO as well as its uniform dispersion throughout the polymeric matrix owing to hydrogen bonding and polar interactions. Also, lower biological degradation of the scaffolds (~30% in 100 days) due to the presence of GO provides essential mechanical support for bone regeneration. In addition, the bioactivity results showed that GO reinforcement significantly increases the biomineralization on the surface of the scaffolds. Evaluating cell adhesion and proliferation, as well as ALP activity of MG-63 cells on PC and PCG scaffolds indicated the positive effect of GO on scaffolds' biocompatibility. Overall, the improvement of physicochemical, mechanical, and biological properties of GO-reinforced scaffolds shows the potential of PCG nanocomposite scaffolds for bone tissue engineering.

Evaluation of the effects of chitosan nanoparticles on polyhydroxy butyrate electrospun scaffolds for cartilage tissue engineering applications.

In this study, we synthesized and incorporated chitosan nanoparticles (Cs) into polyhydroxy butyrate (PHB) electrospun scaffolds for cartilage tissue engineering. The Cs nanoparticles were synthesized via an ionic gel interaction between Cs powder and tripolyphosphate (TPP). The mechanical properties, hydrophilicity, and fiber diameter of the PHB scaffolds with varying concentrations of Cs nanoparticles (1-5 wt%) were evaluated. The results of these evaluations showed that the scaffold containing 1 wt% Cs nanoparticles (P1Cs) was the optimum scaffold, with increased ultimate strength from 2.6 to 5.2 MPa and elongation at break from 5.31 % to 12.6 %. Crystallinity, degradation, and cell compatibility were also evaluated. The addition of Cs nanoparticles decreased crystallinity and accelerated hydrolytic degradation. MTT assay results showed that the proliferation of chondrocytes on the scaffold containing 1 wt% Cs nanoparticles were significantly higher than that on pure PHB after 7 days of cultivation. These findings suggest that the electrospun P1Cs scaffold has promising potential as a substrate for cartilage tissue engineering applications. This combination offers a promising approach for the fabrication of biomimetic scaffolds with enhanced mechanical properties, hydrophilicity, and cell compatibility for tissue engineering applications.

Evaluation of the effects of zein incorporation on physical, mechanical, and biological properties of polyhydroxybutyrate electrospun scaffold for bone tissue engineering applications.

Materials and fabrication methods significantly influence the scaffold's final features in tissue engineering. This study aimed to blend zein with polyhydroxybutyrate (PHB) at 5, 10, and 15 wt%, fabricate scaffolds using electrospinning, and then characterize them. SEM and mechanical analyses identified the scaffold with 10 wt% zein (PHB-10Z) as the optimal sample. Incorporating 10 wt% zein reduced fiber diameter from 894 ± 122 to 531 ± 42 nm while increasing ultimate tensile strength and elongation at break by approximately 53 % and 70 %, respectively. FTIR proved zein's presence in the scaffolds and possible hydrogen bonding with PHB. TGA confirmed the miscibility of polymers. DSC and XRD analyses indicated lower crystallinity for the PHB-10Z than for PHB. AFM evaluation indicated a rougher surface for the PHB-10Z in comparison to PHB. The PHB-10Z demonstrated a more hydrophobic surface and less weight loss after 100 days of degradation in PBS than PHB. The free radical scavenging assay exhibited antioxidant activity for the zein-containing scaffold. Eventually, enhanced cell attachment, viability, and differentiation in the PHB-10Z scaffold drawn from SEM, MTT, ALP activity, and Alizarin red staining of MG-63 cells confirmed that PHB-zein electrospun scaffold is a potent candidate for bone tissue engineering applications.

PCL/Agarose 3D-printed scaffold for tissue engineering applications: fabrication, characterization, and cellular activities.

Background and purpose: Biomaterials, scaffold manufacturing, and design strategies with acceptable mechanical properties are the most critical challenges facing tissue engineering. Experimental approach: In this study, polycaprolactone (PCL) scaffolds were fabricated through a novel three-dimensional (3D) printing method. The PCL scaffolds were then coated with 2% agarose (Ag) hydrogel. The 3D-printed PCL and PCL/Ag scaffolds were characterized for their mechanical properties, porosity, hydrophilicity, and water absorption. The construction and morphology of the printed scaffolds were evaluated via Fourier-Transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The attachment and proliferation of L929 cells cultured on the scaffolds were investigated through MTT assay on the cell culture study upon the 1st, 3rd, and 7th days. Findings/Results: The incorporation of Ag hydrogel with PCL insignificantly decreased the mechanical strength of the scaffold. The presence of Ag enhanced the hydrophilicity and water absorption of the scaffolds, which could positively influence their cell behavior compared to the PCL scaffolds. Regarding cell morphology, the cells on the PCL scaffolds had a more rounded shape and less cell spreading, representing poor cell attachment and cell-scaffold interaction due to the hydrophobic nature of PCL. Conversely, the cells on the PCL/Ag scaffolds were elongated with a spindle-shaped morphology indicating a positive cell-scaffold interaction. Conclusion and implications: PCL/Ag scaffolds can be considered appropriate for tissue-engineering applications.

Plasma surface modification of electrospun polyhydroxybutyrate (PHB) nanofibers to investigate their performance in bone tissue engineering.

Polyhydroxybutyrate (PHB) is a natural-source biopolymer of the polyhydroxyalkanoate (PHA) family. Nanofibrous scaffolds prepared from this biological macromolecule have piqued the interest of researchers in recent years due to their unique properties. Nonetheless, these nanofibers continue to have problems such as low surface roughness and high hydrophobicity. In this research, PHB nanofibers were produced by the electrospinning method. Following that, the surface of nanofibers was modified by atmospheric plasma. Scanning electron microscopy (SEM), water contact angle (WCA), atomic force microscopy (AFM), tensile test, and cell behavior analyses were performed on mats to investigate the performance of treated and untreated samples. The achieved results showed a lower water contact angle (from ≃120° to 43°), appropriate degradation rate (up to ≃20 % weight loss in four months), and outstanding biomineralization (Ca/P ratio of ≃1.86) for the modified sample compared to the neat PHB. Finally, not only the MTT test show better viability of MG63 osteoblast cells, but also Alizarin staining, ALP, and SEM results likewise showed better cell proliferation in the presence of modified mats. These findings back up the claim that plasma surface modification is a quick, environmentally friendly, and low-cost way to improve the performance of nanofibers in bone tissue engineering.

Biological evaluation and osteogenic potential of polyhydroxybutyrate-keratin/Al2O3 electrospun nanocomposite scaffold: A novel bone regeneration construct.

In this study, the effect of alumina nanowire on the physical and biological properties of polyhydroxybutyrate-keratin (PHB-K) electrospun scaffold was investigated. First, PHB-K/alumina nanowire nanocomposite scaffolds were made with an optimal concentration of 3 wt% alumina nanowire by using the electrospinning method. The samples were examined in terms of morphology, porosity, tensile strength, contact angle, biodegradability, bioactivity, cell viability, ALP activity, mineralization ability, and gene expression. The nanocomposite scaffold provided a porosity of >80 % and a tensile strength of about 6.72 MPa, which were noticeable for an electrospun scaffold. AFM images showed an increase in surface roughness with the presence of alumina nanowires. This led to an improvement in the degradation rate and bioactivity of PHB-K/alumina nanowire scaffolds. The viability of mesenchymal cells, alkaline phosphatase secretion, and mineralization significantly increased with the presence of alumina nanowire compared to PHB and PHB-K scaffolds. In addition, the expression level of collagen I, osteocalcin, and RUNX2 genes in nanocomposite scaffolds increased significantly compared to other groups. In general, this nanocomposite scaffold could be a novel and interesting construct for osteogenic induction in bone tissue engineering.

Physical, mechanical, and biological performance of chitosan-based nanocomposite coating deposited on the polycaprolactone-based 3D printed scaffold: Potential application in bone tissue engineering.

Recently, coating on composite scaffolds has attracted many researchers' attention to improve scaffolds' properties. In this research, a 3D printed scaffold was fabricated from polycaprolactone (PCL)/magnetic mesoporous bioactive glass (MMBG)/alumina nanowire (Al2O3, Optimal percentage 5 %) (PMA) and then coated with chitosan (Cs)/multi-walled carbon nanotubes (MWCNTs) by an immersion coating method. Structural analyses such as XRD and ATR-FTIR confirmed the presence of Cs and MWCNTs in the coated scaffolds. The SEM results of the coated scaffolds showed homogeneous three-dimensional structures with interconnected pores compared to the uncoated scaffolds. The coated scaffolds exhibited an increase in compression strength (up to 16.1 MPa) and compressive modulus (up to 40.83 MPa), improved surface hydrophilicity (up to 32.69°), and decrease in degradation rate (68 % remaining weight) compared to the uncoated scaffolds. The increase in apatite formation in the scaffold coated with Cs/MWCNTs was confirmed by SEM, EDAX, and XRD tests. Coating the PMA scaffold with Cs/MWCNTs leads to the viability and proliferation of MG-63 cells and more secretion of alkaline phosphatase and Ca activity, which can be introduced as a suitable candidate for use in bone tissue engineering.