Structures Of Scaffolds Research Articles

Crack propagation in TPMS scaffolds under monotonic axial load: Effect of morphology

In this paper, the mechanical behaviour and failure of porous additively manufactured (AM) polylactide (PLA) scaffolds based on the triply periodic minimal surfaces (TPMS) is investigated using numerical calculations of their unit cells and representative volumes. The strain-amplification factor is chosen as the main parameter, and the most critical locations for failure of different types of scaffold structures are evaluated. The results obtained are presented in comparison with a multiple-crack-growth algorithm using the extended finite element method (XFEM), underpinned by the experimentally obtained fracture properties of PLA. The effect of morphology of TPMS structures on the pre-critical, critical and post-critical behaviours of scaffolds under monotonic loading regimes is assessed. The results provide an understanding of the fracture behaviour and main risk points for crack initiation in structures of AM-PLA scaffolds based on typical commonly used types of TPMS, as well as the influence of structure type and external load on this behaviour.

Advances in Filament Structure of 3D Bioprinted Biodegradable Bone Repair Scaffolds.

Conventional bone repair scaffolds can no longer meet the high standards and requirements of clinical applications in terms of preparation process and service performance. Studies have shown that the diversity of filament structures of implantable scaffolds is closely related to their overall properties (mechanical properties, degradation properties, and biological properties). To better elucidate the characteristics and advantages of different filament structures, this paper retrieves and summarizes the state of the art in the filament structure of the three-dimensional (3D) bioprinted biodegradable bone repair scaffolds, mainly including single-layer structure, double-layer structure, hollow structure, core-shell structure and bionic structures. The eximious performance of the novel scaffolds was discussed from different aspects (material composition, ink configuration, printing parameters, etc.). Besides, the additional functions of the current bone repair scaffold, such as chondrogenesis, angiogenesis, anti-bacteria, and anti-tumor, were also concluded. Finally, the paper prospects the future material selection, structural design, functional development, and performance optimization of bone repair scaffolds.

Modulating the Photophysical Properties of Twisted Donor-Acceptor-Donor π-Conjugated Molecules: Effect of Heteroatoms, Molecular Conformation, and Molecular Topology.

ConspectusModulating the photophysical properties of organic emitters through molecular design is a fundamental endeavor in materials science. A critical aspect of this process is the control of the excited-state energy, which is essential for the development of triplet exciton-harvesting organic emitters, such as those with thermally activated delayed fluorescence and room-temperature phosphorescence. These emitters are pivotal for developing highly efficient organic light-emitting diodes and bioimaging probes. A particularly promising class of these emitters consists of twisted donor-acceptor organic π-conjugated scaffolds. These structures facilitate a spatial separation of the frontier molecular orbitals, which is crucial for achieving a narrow singlet-triplet energy gap. This narrow gap is necessary to overcome the endothermic reverse intersystem crossing process, enhancing the efficiency of thermally activated delayed fluorescence. To precisely modulate the photophysical properties of these emitting materials, it is essential to understand the electronic structures of new donor-acceptor scaffolds, especially those influenced by heteroatoms, as well as their conformations and topologies. This understanding not only improves the efficiency of these emitters but also expands their potential applications in advance technologies.In 2014, the Takeda group made a significant breakthrough by discovering a novel method for synthesizing U-shaped diazaacenes (dibenzo[a,j]phenazine) through an oxidative skeletal rearrangement of 1,1'-binaphthalene-2,2'-diamines. This class of compounds is typically challenging to synthesize using conventional organic reactions. The resulting unique geometric and electronic structure of U-shaped diazaacenes opened new possibilities for photophysical applications. Leveraging the U-shaped structure, photoluminescent properties, and high electron affinity, we developed twisted donor-acceptor-donor compounds. These compounds exhibit efficient thermally activated delayed fluorescence, stimuli-responsive luminochromism, heavy atom-free room-temperature phosphorescence, and anion-responsive red shifts. These innovative emitters have demonstrated significant potential in various practical applications, including organic light-emitting diode devices and advanced sensing systems.In this Account, I summarize our achievements in modulating the photofunctions of dibenzo[a,j]phenazine-cored twisted donor-acceptor-donor compounds by controlling excited-state singlet-triplet energy gaps through conformational regulation. Our comprehensive studies revealed the significant impact of heteroatoms, molecular conformations, and topologies on the photophysics of these compounds. These findings highlight the importance of molecular engineering in tailoring the photophysical properties of organic donor-acceptor π-conjugated materials for specific applications. Our research has demonstrated that incorporating heteroatoms into the molecular framework effectively tunes the electronic properties and, consequently, the photophysical behavior of the compounds. Understanding the influence of heteroatoms, conformational dynamics, and molecular topology on excited-state behavior will open new avenues for next-generation optoelectronic devices and biological technologies. These advancements include ultra-low-power displays, photonic communication, and super-resolution biomedical imaging. Ultimately, our work highlights the potential of strategic molecular design in driving innovation across various fields, paving the way for the development of cutting-edge technologies that leverage the unique properties of organic emitters.

Fabrication and characterization of a bioactive composite scaffold based on polymeric collagen/gelatin/nano β-TCP for alveolar bone regeneration

One strategy to correct alveolar bone defects is use of bioactive bone substitutes to maintain the structure of defect site and facilitate cells and vessels' ingrowth. This study aimed to fabricate and characterize the freeze-dried bone regeneration scaffolds composed of polymeric Type I collagen, nano Beta-tricalcium phosphate (β-TCP), and gelatin. The stable structures of scaffolds were obtained by thermal crosslinking and EDC/NHS ((1-ethyl-3-(3-dimethylaminopropyl) carbodiimide)/(N-hydroxysuccinimide)) chemical crosslinking processes. Subsequently, the physicochemical and biological properties of the scaffolds were characterized and assessed. The results indicated the bioactive composite scaffolds containing 10% and 20% (w/v) nano β-TCP exhibited suitable porosity (84.45 ± 25.43 nm, and 94.51 ± 14.69 nm respectively), a rapid swelling property (reaching the maximum swelling rate at 1 h), excellent degradation resistance (residual mass percentage of scaffolds higher than 80% on day 90 in PBS and Type I collagenase solution respectively), and sustained calcium release capabilities. Moreover, they displayed outstanding biological properties, including superior cell viability, cell adhesion, and cell proliferation. Additionally, the scaffolds containing 10% and 20% (w/v) nano β-TCP could promote the osteogenic differentiation of MC3T3-E1. Therefore, the bioactive composite scaffolds containing 10% and 20% (w/v) nano β-TCP could be further studied for being used to treat alveolar bone defects in vivo.

Effects of immune responses mediated by topological structures of three-dimensional bioprinted scaffolds on hair follicle cycle in mice

Objective: To explore the effects of the immune responses mediated by topological structures of three-dimensional bioprinted scaffolds on hair follicle cycle in mice. Methods: The study was an experimental research. The alginate-gelatin composite hydrogels were printed into scaffolds using a three-dimensional bioprinter and named T45 scaffolds, T60 scaffolds, and T90 scaffolds according to the 3 topological structures of the scaffolds (the rotation angles of the printhead during printing were 45°, 60°, and 90°, respectively), and the morphology of the three scaffolds was observed after cross-linking by naked eyes. Nine 8-week-old female C57BL/6J mice were divided into T45 group, T60 group, and T90 group, according to the random number table, with three mice in each group, and the T45, T60, and T90 scaffolds were subcutaneously implanted on the back of mice, respectively. On post implantation day (PID) 7, the hair growth in the dorsal depilated area of mice was observed, the thickness of the fiber capsule around the scaffolds was observed by hematoxylin-eosin staining, and the expression levels of CD68, bone morphogenetic protein-2 (BMP-2), and tumor necrosis factor (TNF) protein in the tissue surrounding the scaffolds were observed by immunofluorescence staining. The samples of the above experiments were all 3. Results: The topological structures of the three scaffolds were all clear with high fidelity after cross-linking. On PID 7, the hair growth was obvious in the dorsal depilated area of mice in T45 group and T90 group, while hair growth was slow in the scaffold implantation area of mice in T60 group, which was significantly different from that of the unimplanted area. On PID 7, compared with (18±4) μm in T90 group, the thickness of both the fiber capsule around the scaffolds ((39±4) and (55±8) μm) of mice in T45 group and T60 group was significantly increased (P<0.05); the thickness of the fiber capsule around the scaffolds of mice in T60 group was also significantly increased compared with that in T45 group (P<0.05). On PID 7, the expression level of CD68 protein in the tissue surrounding the scaffolds of mice in T60 group was significantly higher than the levels in T45 group and T90 group (with both P values <0.05). The expression level of BMP-2 protein in the tissue surrounding the scaffolds of mice in T60 group was significantly higher than the levels in T45 group and T90 group (with both P values <0.05), and the expression level of BMP-2 protein in the tissue surrounding the scaffolds of mice in T45 group was significantly higher than that in T90 group (P<0.05). The expression level of TNF protein in the tissue surrounding the scaffolds of mice in T60 group was significantly lower than the levels in T45 group and T90 group (with both P values <0.05). Conclusions: Three-dimensional bioprinted scaffolds with different topological structures mediate different degrees of immune responses after being implanted in mice. A moderate immune response promotes hair growth in depilated area of mice, while an excessive immune response results inhibits the hair follicle entering into the anagen phase.

Biomimetic Electrospun Self-Assembling Peptide Scaffolds for Neural Stem Cell Transplantation in Neural Tissue Engineering.

Spinal cord regeneration using stem cell transplantation is a promising strategy for regenerative therapy. Stem cells transplanted onto scaffolds that can mimic natural extracellular matrix (ECM) have the potential to significantly improve outcomes. In this study, we strived to develop a cell carrier by culturing neural stem cells (NSCs) onto electrospun 2D and 3D constructs made up of specific crosslinked functionalized self-assembling peptides (SAPs) featuring enhanced biomimetic and biomechanical properties. Morphology, architecture, and secondary structures of electrospun scaffolds in the solid-state and electrospinning solution were studied step by step. Morphological studies showed the benefit of mixed peptides and surfactants as additives to form thinner, uniform, and defect-free fibers. It has been observed that β-sheet conformation as evidence of self-assembling has been predominant throughout the process except for the electrospinning solution. In vitro NSCs seeded on electrospun SAP scaffolds in 2D and 3D conditions displayed desirable proliferation, viability, and differentiation in comparison to the gold standard. In vivo biocompatibility assay confirmed the permissibility of implanted fibrous channels by foreign body reaction. The results of this study demonstrated that fibrous 2D/3D electrospun SAP scaffolds, when shaped as micro-channels, can be suitable to support NSC transplantation for regeneration following spinal cord injury.

Biomimetic scaffold-based stem cell transplantation promotes lung regeneration.

Therapeutic options are limited for severe lung injury and disease as the spontaneous regeneration of functional alveolar is terminated owing to the weakness of the inherent stem cells and the dyscrasia of the niche. Umbilical cord mesenchymal-derived stem cells (UC-MSCs) have been applied to clinical trials to promote lung repair through stem cell niche restruction. However, the application of UC-MSCs is hampered by the effectiveness of cell transplantation with few cells homing to the injury sites and poor retention, survival, and proliferation in vivo. In this study, we constructed an artificial three-dimensional (3D) biomimetic scaffold-based MSCs implant to establish a beneficial regeneration niche for endogenous stem cells in situ lung regeneration. The therapeutic potential of 3D biomimetic scaffold-based MSCs implants was evaluated by 3D culture in vitro. And RNA sequencing (RNA-Seq) was mapped to explore the gene expression involved in the niche improvement. Next, a model of partial lung resection was established in rats, and the implants were implanted into the operative region. Effects of the implants on rat resected lung injury repair were detected. The results revealed that UC-MSCs loaded on biomimetic scaffolds exerted strong paracrine effects and some UC-MSCs migrated to the lung from scaffolds and had long-term retention to suppress inflammation and fibrosis in residual lungs and promoted vascular endothelial cells and alveolar type II epithelial cells to enter the scaffolds. Then, under the guidance of the ECM-mimicking structures of scaffolds and the stimulation of the remaining UC-MSCs, vascular and alveolar-like structures were formed in the scaffold region. Moreover, the general morphology of the operative lung was also restored. Taken together, the artificial 3D biomimetic scaffold-based MSCs implants induce in situ lung regeneration and recovery after lung destruction, providing a promising direction for tissue engineering and stem cell strategies in lung regeneration.

Gradient scaffolds developed by parametric modeling with selective laser sintering

In bone tissue engineering, gradient scaffolds have drawn more attention for having better bionic characteristics than uniform scaffolds. In this study, a parameterized method for developing scaffolds with customized compression modulus distribution was proposed based on selective laser sintering (SLS) and the Primitive triply periodic minimal surfaces (TMPS). Uniform and gradient scaffolds were modeled by the developed method and prepared using polyamide 12 (PA12) material. Then, analysis of the mechanical properties, the energy absorption characteristics, and the permeability of the designed Primitive porous scaffolds was conducted with compression experiments and computational fluid dynamics (CFD). The results demonstrate that the proposed parametric modeling method enables the effective fabricating of gradient porous scaffolds with expected mechanical performance. Further, the gradient scaffolds have a comprehensive performance of both agreeable mechanical properties and permeability. Meanwhile, cell tests show that the irregular structures of the gradient scaffolds promote cell adhesion and migration, which is favorable for the growth of bone tissue. These findings provide guidelines for developing customized gradient scaffolds, and promote the application of energy-absorbing or cell proliferation structures in engineering.

Controlled mechanical and mass-transport properties of porous scaffolds through hollow strut

The rational design of bone implants is relatively complex because they should meet a unique combination of mechanical, mass-transport, and biological properties for favorable performance. However, in conventional topological structures of scaffolds, some important properties are coupled, which hampers the achievement of optimal performance. For example, it is difficult to enhance the stiffness and mass-transport properties of a scaffold simultaneously. This study aims to obtain controlled mechanical and mass-transport properties of scaffolds through adding an inner pore within the strut. The experimental results suggest that permeability and mechanical property were decoupled to a good extent, e.g., the elastic modulus of the four fabricated samples ranges from 1428.6 MPa to 3924.4 MPa, while the counterpart permeability distribution ranges from 11.08 × 10−9 m2 to 12.35 × 10−9 m2 (only 10% difference). Then, combination of the stiffness and permeability was controlled through porosity and inner pore. The simulated results show that permeability is sensitive to both the added inner pore and porosity while elastic modulus depends largely on the porosity, which provides a robust and straightforward approach to tailor the mechanical and mass-transport properties. The hollow-strut structure allows for greater design freedom in the combination of multi-physical properties, which provides a promising basis to the design of high-performance bone implants.

2-Aminothiazole-Oxadiazole Bearing N-Arylated Butanamides: Convergent Synthesis, Tyrosinase Inhibition, Kinetics, Structure-Activity Relationship, and Binding Conformations.

A multi-step synthesis of novel bi-heterocyclic N-arylated butanamides was consummated through a convergent strategy and the structures of these medicinal scaffolds, 7a-h, were corroborated using spectral techniques. The in vitro analysis of these hybrid molecules revealed their potent tyrosinase inhibition as compared to the standard used. The kinetics mechanism was investigated through Lineweaver-Burk plots which exposed that, 7f, inhibited tyrosinase enzyme non-competitively by forming the enzyme-inhibitor complex. The inhibition constants Ki calculated from Dixon plots for this compound was 0.025 μM. Their binding conformations were ascertained by in silico computational studies whereby these molecules disclosed good binding energy values (kcal/mol). So, it was anticipated from the current research that these bi-heterocyclic butanamides might be probed as imperative therapeutic agents for melanogenesis.

Characteristic Evaluation of Recombinant MiSp/Poly(lactic-co-glycolic) Acid (PLGA) Nanofiber Scaffolds as Potential Scaffolds for Bone Tissue Engineering.

Biomaterial-based nanofibrous scaffolds are the most effective alternative to bone transplantation therapy. Here, two recombinant minor ampullate spidroins (spider silk proteins), R1SR2 and NR1SR2C, were blended with Poly(lactic-co-glycolic) Acid (PLGA), respectively, to generate nanofiber scaffolds by electrospinning. The N-terminal (N), C-terminal (C), repeating (R1 and R2) and spacer (S) modules were all derived from the minor ampullate spidroins (MiSp). The physical properties and structures of the blended scaffolds were measured by scanning electron microscopy (SEM), water contact angle measurement, Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), and Tensile mechanical testing. The results showed that blending of MiSp (R1SR2 and NR1SR2C) reduced the diameter of nanofibers, increased the porosity and glass transition temperatures of nanofibrous scaffolds, and effectively improved the hydrophilicity and ultimate strain of scaffolds. It is worth noting that the above changes were more significant in the presence of the N- and C-termini of MiSp. In cell culture assays, human bone mesenchymal stem cells (HBMSCs) grown on NR1SR2C/PLGA (20/80) scaffolds displayed markedly enhanced proliferative and adhesive abilities compared with counterparts grown on pure PLGA scaffolds. Jointly, these findings indicated recombinant MiSp/PLGA, particularly NR1SR2C/PLGA (20/80) blend nanofibrous scaffolds, is promising for bone tissue engineering.

Ceramic Scaffolds for Bone Augmentation: Design and Characterization with SEM and Confocal Microscopy

Bone scaffolds must fulfil numerous and sometimes contradictory characteristics: biocompatibility, bioactivity, high porosity, and appropriate mechanical strength. To tackle some of these issues, this study has several aims for the development of such scaffolds for dentistry applications: (i) to utilize appropriate materials (ceramics and sponges) and to introduce a novel, potentially performant ceramic material; (ii) to characterize the obtained scaffolds by using a range of methods; (iii) to compare and to correlate the assessment results with the scope to validate them reciprocally. There are two commercially available dental ceramics (i.e., Ceramco iC Natural Enamel (E) and Ceramco iC Natural Dentine (D), (DeguDent GmbH, Hanau-Wolfgang, Deutschland)) that are considered, as well as a new-developed porcelain (ceramic C). To obtain porous structures of scaffolds, each ceramic is introduced in two different sponges: a denser one, green (G) and a less dense one, blue (B). A total of 60 samples are manufactured and divided in six study groups, obtained by combining the above materials: GE, BE, GD, BD, GC, and BC (where the first letter represents the sponge type and the second one the utilized ceramic). Several methods are applied to characterize their chemical composition, as well as their macro- and micro-porosity: X-ray Diffraction (XRD), apparent porosity measurements, scanning electronic microscopy (SEM), and confocal microscopy (CM). The latter two methods image the inner (porous) and the outer/cortical (denser) areas of the samples. The results show a good porosity (i.e., dimensions and uniformity of pores) of around 65% for the final group BC, with satisfactory values of around 51% for BD and GC. A certain correlation is made between SEM, CM, and the apparent porosity results. The biocompatibility of the new ceramic C is demonstrated. Finally, a necessary trade-off is made with the mechanical strength of the obtained scaffolds, which was also evaluated. From this point of view, Group BD has the highest compressive strength of around 4 MPa, while Group BC comes second, with around 2 MPa. This trade-off between porosity and mechanical strength suggests a choice between Groups BC and BD, which are the best with regard to the porosity and mechanical strength criterium, respectively.

Finite element analysis of the influence of porosity and pore geometry on mechanical properties of orthopaedic scaffolds

PurposeScaffolds play a key role in regenerative medicine in the repair of injuries, defects and cancerous changes in long bones. For this reason, scaffolds should meet certain mechanobiological requirements, such as adequate porosity and pore geometry to ensure appropriate osteointegration as well as load transfer. Taking into account the most frequently used cell units, this study attempted to evaluate the porous structures of orthopaedic scaffolds in terms of their strength parameters. Materials and methodsFour pore geometries were selected for analyses: sphere, octagonal prism, cube and triangular prism, all with porosities of 10% up to 60%. Three different material properties were considered: Ti6Al4V alloy, CoCr alloy, 316 L steel. Strength compression simulations were carried out on 144 models, 72 structures of cell units with dimensions of 4 × 4 × 4 mm and 72 structures of scaffolds with a diameter of 16 mm and a height of 15 mm. Effective Young's modulus, as well as 0.2%, offset effective yield strength was estimated. ResultsResearch has shown that scaffolds with bone-like strength properties should be made of Ti6Al4V alloy. The value of 40% turned out to be of the best porosity. The remaining porosities showed much lower or much higher strength parameters and were significantly different from the properties of the bones. ConclusionsThe obtained data allow to indicate the most functional porous structure with Young's modulus similar to that possesses by core bone, while maintaining mechanical strength, allowing for its appropriate use in orthopaedic regenerative medicine.

The Three-Dimensional Structure of Porcine Bladder Scaffolds Alters the Biology of Murine Diabetic Wound Healing.

To determine if the various three-dimensional structures of bioscaffolds affect wound healing by investigating the efficacy of different porcine-derived urinary bladder matrix (UBM) structures in treating murine diabetic wound healing. The authors studied three different UBM structures: particulate (pUBM), one-layer freeze-dried sheet (fdUBM), and three-layer laminated sheet (lmUBM). Scanning electron microscopy images of the structures were used to calculate a wound-exposed surface-area-to-volume ratio. A 1.0 × 1.0-cm full-thickness dorsal wound was excised on 90 db/db mice. Mice were either untreated (blank, n = 15), treated with one UBM structure (pUBM, n = 15; fdUBM, n = 15; lmUBM, n = 15), or treated with a combination of either the one- or three-layer sheet over the particulate matrix (fdUBM + pUBM, n = 15; lmUBM + pUBM, n = 15). The authors obtained macroscopic images of the wounds and harvested tissues for analyses at multiple time points. The surface area available to interact with the wound was highest in the pUBM group and lowest in the lmUBM group. Greater wound bed thickness was noted in the fdUBM, fdUBM + pUBM, and lmUBM groups compared with the blank group. Cellular proliferation was significantly higher in the fdUBM and fdUBM + pUBM groups than in the blank group. The lmUBM + pUBM group had the highest collagen deposition. The pUBM group induced significantly higher leukocyte infiltration compared with the lmUBM, lmUBM + pUBM, and blank groups. Microvessel density was highest in the fdUBM + pUBM group. Significant differences in the wound closure rate were noted between the blank group and the fdUBM and fdUBM + pUBM groups. Assessment of the three UBM bioscaffold structures highlighted differences in the wound-exposed surface area. Variations in wound healing effects, including collagen deposition, cellular proliferation, and angiogenesis, were identified, with combinations of the structures displaying synergistic effects. This study serves as a platform for future scaffold design and offers promising evidence of the benefits of combining various structures of scaffolds.

Facile synthesis of hydroxyapatite from bovine bone and gelatin/chitosan‐hydroxyapatite scaffold for potential tissue engineering application

AbstractHere, hydroxyapatite was obtained from bovine bones by thermal decomposition at temperatures from 550 to 850°C at the time of 5 hours. The physical characterization showed that all organic components in the bovine bones were eliminated and produced the clean hydroxyapatite. Composite scaffolds were made of the gelatin (G), chitosan (C), and hydroxyapatite (HAp) in various gelatin/chitosan‐HAp mass ratios by the freeze‐drying method. The FT‐IR, SEM, XRD, and EDX techniques were used to examine the structures of synthetic HAp and composite scaffolds. XRD showed three main peaks at 2θ = 31.8, 33.1, and 40.1o, which resembled the characteristic peaks of hydroxyapatite and approved the formation of HAp at 850°C. FT‐IR results at 1360 and 1554 cm‐1 confirmed the formation of –C=N‐ bond of the interaction between chitosan and gelatin to form a 3D interconnected network in scaffolds. The swelling and in‐vitro degradation of composite scaffolds were carried out in PBS and 10 %FBS + PBS solutions. All composite scaffolds demonstrated the cell viability of L929 was above 95 %. These results indicated that the composite showed a potential application in tissue engineering.

Design and analysis of the mechanical properties of controllable porous scaffolds for bone tissue engineering.

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3D Printed Gelatin/Sodium Alginate Hydrogel Scaffolds Doped with Nano-Attapulgite for Bone Tissue Repair.

IntroductionBone tissue engineering (BTE) is a new strategy for bone defect repair, but the difficulties in the fabrication of scaffolds with personalized structures still limited their clinical applications. The rapid development in three-dimensional (3D) printing endows it capable of controlling the porous structures of scaffolds with high structural complexity and provides flexibility to meet specific needs of bone repair.MethodsIn this study, sodium alginate (SA)/gelatin (Gel) hydrogel scaffolds doped with different contents of nano-attapulgite were fabricated via 3D printing. The surface microstructure, hydrophilicity and mechanical properties were fully evaluated. Furthermore, mouse bone marrow-derived mesenchymal stem cells (BMSCs) were cultured with the composite hydrogels in vitro, and proliferation and osteoblastic differentiation were assessed. A rabbit tibia plateau defect model was used to evaluate the osteogenic potential of the composite hydrogel in vivo.ResultsWhen increasing nano-ATP content, the Gel/SA/nano-ATP composite hydrogels showed better mechanical property and printability. Moreover, Gel/SA/nano-ATP composite hydrogels showed excellent bioactivity, and a significant mineralization effect was observed on the surface after being incubated in simulated body fluid (SBF) for 14 days. The Gel/SA/nano-ATP composite hydrogel also showed good biocompatibility and promoted the osteogenesis of BMSCs. Finally, histological analysis demonstrates that the Gel/SA/nano-ATP composite hydrogels could effectively enhance bone regeneration in vivo.ConclusionThese properties render the Gel/SA/nano-ATP composite hydrogel scaffolds an ideal bone tissue engineering material for the repair of bone defects.

Fabrication of collagen with polyhexamethylene biguanide: A potential scaffold for infected wounds.

Bacterial infection remains a great challenge in wound healing, especially in chronic wounds. Multidrug-resistant organisms are increasing in acute and chronic wound infections, which compromise the chance of therapeutics. Resistance to conventional antibiotics has created an urge to study new approach/system that can effectively control wound infection and enhance healing. Wound cover/dressing must exhibit biocompatibility and effectiveness in reducing bioburden at the wound site. Collagen, a natural biopolymer, possesses advantages over synthetic and other natural materials due to its unique biological properties. It can act as an excellent wound dressing and controlled drug delivery system. Currently, antiseptic agents such as silver, iodine, and polyhexamethylene biguanide (PHMB)-incorporated scaffolds have become widely accepted in chronic wound healing. In this study, PHMB-incorporated collagen scaffold has been prepared and characterized using Fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), and differential scanning calorimetry (DSC), which showed retention of collagen nativity and integration of PHMB. The scanning electron microscopy (SEM) analysis revealed the porous structures of scaffolds. The cytotoxicity analysis showed PHMB is nontoxic at the concentration of 0.01% (wt/wt). The agar diffusion test and bacterial adhesion study demonstrated the effectiveness of PHMB-incorporated collagen scaffold against both gram positive and negative strains. This study concludes that PHMB-incorporated collagen scaffold could have the potential for infected wound healing.

Proteasome Biology: Chemistry and Bioengineering Insights.

Proteasomal degradation provides the crucial machinery for maintaining cellular proteostasis. The biological origins of modulation or impairment of the function of proteasomal complexes may include changes in gene expression of their subunits, ubiquitin mutation, or indirect mechanisms arising from the overall impairment of proteostasis. However, changes in the physico-chemical characteristics of the cellular environment might also meaningfully contribute to altered performance. This review summarizes the effects of physicochemical factors in the cell, such as pH, temperature fluctuations, and reactions with the products of oxidative metabolism, on the function of the proteasome. Furthermore, evidence of the direct interaction of proteasomal complexes with protein aggregates is compared against the knowledge obtained from immobilization biotechnologies. In this regard, factors such as the structures of the natural polymeric scaffolds in the cells, their content of reactive groups or the sequestration of metal ions, and processes at the interface, are discussed here with regard to their influences on proteasomal function.

Synthesis and Anticancer Activity of New 2-Aryl-4-(4-Methoxybenzylidene)-5-Oxazolone Scaffolds

A new series of 4-(4-methoxybenzylidene)-2-substitutedphenyl-5(4H)-oxazolone derivatives has been synthesized through the application of Erlenmeyer condition (Ac2O, AcONa, and 4-anisaldehyde) to the reaction products of the highly versatile p-aminohippuric acid with various electrophilic reagents such as aromatic aldehydes, phenyl isothiocyanate, diazotization-coupling reaction (malononitrile and 2-amino-4-phenylthiazole) and cyanoacetyl-pyrazole. IR, 1H NMR, and mass spectroscopic techniques were utilized to confirm the structures of these oxazolone scaffolds. The synthesized oxazolone derivatives were evaluated against four human cancer cell lines (HepG2, HTC-116, PC-3, and MCF-7). Compound 3e showed the best activity against hepatocellular carcinoma (IC50 8.9±0.30 μg/mL) and colorectal carcinoma (IC50 9.2±0.63 μg/mL) cell lines compared with the standard anticancer drug 5-fluorouracil.