Layered Scaffolds Research Articles

Structure, Properties and Degradation of Self-Assembled Fibrinogen Nanofiber Scaffolds.

Self-assembled fibrinogen nanofibers are promising candidates for skin tissue engineering due to their biocompatibility and ability to mimic the native blood clot architecture. Here, we studied the structure-property relationship and degradation of rehydrated fibrinogen nanofibers prepared by salt-induced self-assembly, focusing on the effect of scaffold layering, cross-linking time and freeze-drying. Optimal fiber stability was achieved with cross-linking by formaldehyde (FA) vapor, while treatment with liquid aldehydes, genipin, EDC, and transglutaminase failed to preserve the nanofibrous architecture upon rehydration. Scaffold layering did not significantly influence the mechanical properties but changed the scaffold architecture, with bulk fiber scaffolds being more compact than layered scaffolds. Freeze-drying maintained the mechanical properties and interconnected pore network with average pore diameters around 20 μm, which will enhance the storage stability of self-assembled fibrinogen scaffolds. Varying cross-linking times altered the scaffold mechanics without affecting the swelling behavior, indicating that scaffold hydration can be controlled independently of the mechanical characteristics. Cross-linking times of 240 min increased scaffold stiffness and decreased elongation, while 30 min resulted in mechanical properties similar to native skin. Cross-linking for 120 min was found to reduce scaffold degradation by various enzymes in comparison to 60 min. Overall, after 35 days of incubation, plasmin and a combination of urokinase and plasminogen exhibited the strongest degradative effect, with nanofibers being more susceptible to enzymatic degradation than planar fibrinogen due to their higher specific surface area. Based on these results, self-assembled fibrinogen fiber scaffolds show great potential for future applications in soft tissue engineering that require controlled structure-function relationships and degradation characteristics.

Experimental testing and mechanism investigation of amine-functionalized layered vermiculite for CO2 capture

Solid amine adsorbents have attracted significant attention due to their low energy consumption, high selectivity, and environmental friendliness, positioning them as the most promising technology for CO2 capture. However, current adsorbent carrier materials commonly encounter challenges such as expensive costs and inadequate stability. In this study, acid-activated expanded vermiculite carrier (AEV) with a large pore volume and hierarchical pore structure was prepared. Subsequently, a series of functionalized polyethyleneimine (PEI) adsorbents were synthesized and employed in CO2 capture experiments to investigate the impact of PEI loading and temperature on adsorption characteristics. The results showed that the acid-modified expanded vermiculite with a large pore volume structure significantly increased amine loading, while the layered structure network promoted amine dispersion. Under the conditions of 50 wt% PEI loading, the CO2 capture capacity of AEV reached 3.29 mmol/L at 75 ℃. Furthermore, density functional theory was utilized to calculate the adsorption energy and Gibbs free energy change of CO2 and polyethyleneimine molecules. The HOMO and LUMO distributions of CO2 molecules with different polyethyleneimine chains were determined using frontier orbital theory, combined with infrared spectroscopy results confirming the conversion of CO2 into carbamate. Additionally, AEV-PEI50 adsorbent exhibited good stability during 8 cycles of the adsorption process. The obtained results demonstrate that the utilization of layered mesoporous scaffolds offers notable benefits in terms of efficient CO2 capture.

Development of Super-Paramagnetic Iron Oxide Nanoparticle-Coated Melt Electrowritten Scaffolds for Biomedical Applications.

Polycaprolactone (PCL) is usually the material chosen for melt electrowriting (MEW) due to its biocompatibility, mechanical strength, and melt processability. This work first investigates the effect of different processing parameters to obtain optimum PCL-MEW scaffolds. Secondly, to increase PCL`s hydrophilicity and cell affinity, and to enable coating with superparamagnetic iron oxide nanoparticles (SPIONs) and silica-coated-SPIONs (Si-SPIONs), the scaffolds are modified with alkaline surface treatment. Finally, SPIONs and Si-SPIONs are successfully coated on MEW scaffolds. Results show that reproducible scaffolds are fabricated. Additionally, the alkaline treatment does not change the three-dimensionalmorphology of scaffolds while reducing fiber diameter. Furthermore, SEM images and ATR-FTIR results confirmed that SPIONs and Si-SPIONs-were coated on scaffolds. A cytocompatibility assay showed a non-toxic effect on MG-63 osteoblast-like cells in all scaffolds. Additionally, higher MC3T3-E1 pre-osteoblastic cell adhesion efficiency and proliferation are achieved for the alkaline-treated scaffolds and SPIONs/Si-SPIONs-coated scaffolds. All samples demonstrated the ability to generate heat, useful for hyperthermia-treatment, when subjected to an alternating magnetic field. Overall, the findings suggest that the strategy of coating PCL-MEW scaffolds with SPIONs/Si-SPIONs has the potential to improve scaffold performance for biomedical applications, especially for producing magnetically responsive MEW scaffolds.

Layered PCL scaffolds modified with bioactive additives fabricated by electrospinning and 3D-printing for the nasal bone and cartilage defects

This paper presents a method for fabricating layered materials supporting the reconstruction of nasal tissues by combining the 3D/fused deposition modeling (FDM) technology with electrospinning (ES). Polycaprolactone (PCL) scaffolds modified with bioglass (BG) and zinc (Zn)-doped BG were printed from the connectable filaments sticks. Then, using the ES, a nanofibrous membrane with particles of the pharmaceutical drug Osteogenon (OST), was applied directly on a spatial scaffold. The layered scaffolds were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and micro-computed tomography (µCT). The bioactivity and biocompatibility of the scaffolds were evaluated by in vitro studies. The results indicated that the presence of the OST drug in the top layer of scaffolds promoted bioactivity. The presence of a membrane had a positive effect on the production and secretion of aggrecan (Agg), and incorporation of BG particles significantly improved the production and secretion of collagen type II (Col2). Each of the introduced PCL modifications leads to articular cartilage cell (NHAC-kn) viability improvement and results in a decrease in the cytotoxicity of the material. Moreover, in the long-term culture, cell proliferation was positively affected by the introduction of the OST-modified membrane and also by the addition of Zn-doped BG particles.

Nacre-mimetic cerium-doped nano-hydroxyapatite/chitosan layered composite scaffolds regulate bone regeneration via OPG/RANKL signaling pathway

Autogenous bone grafting has long been considered the gold standard for treating critical bone defects. However, its use is plagued by numerous drawbacks, such as limited supply, donor site morbidity, and restricted use for giant-sized defects. For this reason, there is an increasing need for effective bone substitutes to treat these defects. Mollusk nacre is a natural structure with outstanding mechanical property due to its notable “brick-and-mortar” architecture. Inspired by the nacre architecture, our team designed and fabricated a nacre-mimetic cerium-doped layered nano-hydroxyapatite/chitosan layered composite scaffold (CeHA/CS). Hydroxyapatite can provide a certain strength to the material like a brick. And as a polymer material, chitosan can slow down the force when the material is impacted, like an adhesive. As seen in natural nacre, the combination of these inorganic and organic components results in remarkable tensile strength and fracture toughness. Cerium ions have been demonstrated exceptional anti-osteoclastogenesis capabilities. Our scaffold featured a distinct layered HA/CS composite structure with intervals ranging from 50 to 200 μm, which provided a conducive environment for human bone marrow mesenchymal stem cell (hBMSC) adhesion and proliferation, allowing for in situ growth of newly formed bone tissue. In vitro, Western-blot and qPCR analyses showed that the CeHA/CS layered composite scaffolds significantly promoted the osteogenic process by upregulating the expressions of osteogenic-related genes such as RUNX2, OCN, and COL1, while inhibiting osteoclast differentiation, as indicated by reduced TRAP-positive osteoclasts and decreased bone resorption. In vivo, calvarial defects in rats demonstrated that the layered CeHA/CS scaffolds significantly accelerated bone regeneration at the defect site, and immunofluorescence indicated a lowered RANKL/OPG ratio. Overall, our results demonstrate that CeHA/CS scaffolds offer a promising platform for bone regeneration in critical defect management, as they promote osteogenesis and inhibit osteoclast activation.

Buried Interface Dielectric Layer Engineering for Highly Efficient and Stable Inverted Perovskite Solar Cells and Modules.

Stability and scalability are essential and urgent requirements for the commercialization of perovskite solar cells (PSCs), which are retarded by the non-ideal interface leading to non-radiative recombination and degradation. Extensive efforts are devoted to reducing the defects at the perovskite surface. However, the effects of the buried interface on the degradation and non-radiative recombination need to be further investigated. Herein, an omnibearing strategy to modify buried and top surfaces of perovskite film to reduce interfacial defects, by incorporating aluminum oxide (Al2 O3 ) as a dielectric layer and growth scaffolds (buried surface) and phenethylammonium bromide as a passivation layer (buried and top surfaces), is demonstrated. Consequently, the open-circuit voltage is extensively boosted from 1.02 to 1.14V with the incorporation of Al2 O3 filling the voids between grains, resulting in dense morphology of buried interface and reduced recombination centers. Finally, the impressive efficiencies of 23.1% (0.1 cm2 ) and 22.4% (1 cm2 ) are achieved with superior stability, which remain 96% (0.1 cm2 ) and 89% (1 cm2 ) of its initial performance after 1200 (0.1 cm2 ) and 2500h (1 cm2 ) illumination, respectively. The dual modification provides a universal method to reduce interfacial defects, revealing a promising prospect in developing high-performance PSCs and modules.

Alginate sulfate/ECM composite hydrogel containing electrospun nanofiber with encapsulated human adipose-derived stem cells for cartilage tissue engineering

Stem cell therapy is a promising strategy for cartilage tissue engineering, and cell transplantation using polymeric scaffolds has recently gained attention. Herein, we encapsulated human adipose-derived stem cells (hASCs) within the alginate sulfate hydrogel and then added them to polycaprolactone/gelatin electrospun nanofibers and extracellular matrix (ECM) powders to mimic the cartilage structure and characteristic. The composite hydrogel scaffolds were developed to evaluate the relevant factors and conditions in mechanical properties, cell proliferation, and differentiation to enhance cartilage regeneration. For this purpose, different concentrations (1–5 % w/v) of ECM powder were initially loaded within an alginate sulfate solution to optimize the best composition for encapsulated hASCs viability. Adding 4 % w/v of ECM resulted in optimal mechanical and rheological properties and better cell viability. In the next step, electrospun nanofibrous layers were added to the alginate sulfate/ECM composite to prepare different layered hydrogel-nanofiber (2, 3, and 5-layer) structures with the ability to mimic the cartilage structure and function. The 3-layer structure was selected as the optimum layered composite scaffold, considering cell viability, mechanical properties, swelling, and biodegradation behavior; moreover, the chondrogenesis potential was assessed, and the results showed promising features for cartilage tissue engineering application.

Facile mussel-inspired polymerization to facilitate biomimetic in situ homogeneous mineralization for bone regeneration

As a mussel-inspired polymer, polydopamine (PDA) coating can be used as a simple and universal way to form nano-hydroxyapatite (nHAP) crystals on a variety of substrates. Therefore, PDA is widely used in the preparation of bone repair materials. However, its uneven distribution and easy degradation under strongly alkaline conditions limit its application. Therefore, based on the principle of in situ regeneration, this study combined the freeze-drying technology with the diffusion method of ammonium carbonate to bionics construct porous micro-nano composite scaffolds. Chitosan (CS) and dopamine hydrochloride (DA) were used as the chief components to form a multilayer layered scaffold structure. PDA and nHAP grow in situ on the surface of the freeze-dried scaffolds after ammonium carbonate gas diffusion treatment and Tris buffer immersion. The mild synthesis method effectively avoided the decomposition of PDA, and the gas diffusion method promoted the uniform distribution of PDA. The effect of PDA on nHAP formation was studied by adjusting the amount of DA. The cross-linking reaction between PDA and CS was verified by FTIR and XPS. Surface morphology was observed by SEM. The formation of nHAP was confirmed by XRD. The scaffolds had good porosity, degradation, water absorption, thermal stability and biomimetic mineralization properties. Cell experiments showed that the scaffolds had good biocompatibility and had no toxicity to cells. The construction of bone defect animal model further verified that the scaffolds promoted bone regeneration in the defect site of the body. This study provided a new idea and method for the preparation of bone repair scaffolds.

Nacre-inspired magnetically oriented micro-cellulose fibres/nano-hydroxyapatite/chitosan layered scaffold enhances pro-osteogenesis and angiogenesis.

In situ regeneration of large-segment bone defects is a difficult clinical problem. Here, we innovatively developed magnetically oriented micro-cellulose fibres using nano-hydroxyapatite/chitosan (CEF/Fe3O4/HA/CS) and loaded an NFκB pathway inhibitor on the surface of magnetically oriented cellulose fibres (CEF/Fe3O4/HA/CS/PQQ) prepared as a layered bioscaffold. CEF/Fe3O4/HA/CS/PQQ was constructed by layering HA/CS sheets. Nano-hydroxyapatite was deposited on the surface of cellulose fibres, then the magnetic nanoparticles on the cellulose fibres were aligned on the surface of chitosan under a magnetic field. Oriented cellulose fibres enhanced the compressive properties of the scaffold, with an average maximum compressive strength of 1.63 ​MPa. The CEF/Fe3O4/HA/CS/PQQ layered scaffold was filled into the body, and the acute inflammatory response (IL-1β and TNF-α) was suppressed through the early sustained release of PQQ. The CEF/Fe3O4/HA/CS/PQQ-layered scaffold further inhibited the osteoclasts differentiation. It was further found that the nano-hydroxyapatite on the surface of oriented cellulose fibres promoted the formation and migration of new blood vessels, accelerated the processing of collagen-I fibres to cartilage, and endochondral ossification. Hence, the development of the CEF/Fe3O4/HA/CS/PQQ layered scaffold with oriented fibres guides bone growth direction and pro-osteogenesis activity and provides a novel strategy for the in situ regeneration of large segmental bone defects.

Highly effective electrospun polycaprolactone/ layered double hydroxide nanofibrous scaffold for bone tissue engineering

Bone tissue engineering is considered a promising approach for repairing, regenerating and orthopedic implants. In this regard, polymeric supportive scaffolds reinforced with bioactive nanomaterials provide unique functions help in substitution of impaired bone tissues. In this constant, various layered double hydroxide (LDH) concentrations (ranging from 0.1 wt% to 10 wt%.) within the poly (ε-caprolactone) (PCL) scaffolds were fabricated successfully through electrospinning. The scaffolds were investigated by XRD, SEM, FTIR, and EDX analyses to study the phase identification, morphology, chemical properties, and elemental composition, respectively. The findings demonstrated that the inclusion of LDH to PCL scaffold increased mechanical tensile strength from 1.63 ± 0.4 to 1.920 ± 0.3 Mpa for the pure PCL and PCL + LDH (1 wt%) scaffolds, respectively. A decrease in the average diameter of PCL nanofibers was observed with the addition of LDH. The enrichment of PCL scaffold with LDH promotes in vitro biomineralization when subjected to simulated body fluid (SBF), indicating the bioactive features of the nanocomposite scaffolds. In addition, increased of LDH leads to improvement in protein adsorption capacity compared to the pure one. Furthermore, the cytocompatibility and cytotoxicity of nanocomposite fibers was assessed using human MG-63 osteoblast-like cells. The LDH/PCL scaffold induced mineral deposition and osteogenic differentiation of MG-63 as evident by an increase in ALP activity in comparison with the pure PCL. Overall, our results revealed that electrospun PCL-LDH nanofiber might be an ideal choice for bone tissue engineering.

Layered scaffolds in periodontal regeneration.

Periodontitis is a common inflammatory disease in dentistry that may lead to tooth loss and aesthetic problems. Periodontal tissue has a sophisticated architecture including four sections of alveolar bone, cementum, gingiva, and periodontal ligament fiber; all these four can be damaged during periodontitis. Thus, for whole periodontal regeneration, it is important to form both hard and soft tissue structures simultaneously on the tooth root surface without forming junctional epithelium and ankylosis. This condition makes the treatment of the periodontium a challenging process. Various regenerative methods including Guided Bone/Tissue Regeneration (GBR/GTR) using various membranes have been developed. Although using such GBR/GTR membranes was successful for partial periodontal treatment, they cannot be used for the regeneration of complete periodontium. For this purpose, multilayered scaffolds are now being developed. Such scaffolds may include various biomaterials, stem cells, and growth factors in a multiphasic configuration in which each layer is designed to regenerate specific section of the periodontium. This article provides a comprehensive review of the multilayered scaffolds for periodontal regeneration based on natural or synthetic polymers, and their combinations with other biomaterials and bioactive molecules. After highlighting the challenges related to multilayered scaffolds preparation, features of suitable scaffolds for periodontal regeneration are discussed.

Preparation and Characterization of 3D Printed Porous 45S5 Bioglass Bioceramic for Bone Tissue Engineering Application.

Three-dimensional (3D) printing technology provides advanced technical support for designing personalized bone tissue engineering scaffold. In this study, two porous diffusing models, namely, average and layered perforated cylindrical scaffolds, were designed for bone tissue engineering scaffold. The designed models were fabricated by liquid crystal display mask stereolithography printing. Structural design and finite element mechanical analysis were conducted. 45S5 bioglass was selected as the raw material for preparing the printing inks for bone tissue engineering scaffolds. By adjusting the viscosity and temperature of the slurry, the maximum proportion of 45S5 bioglass (40 wt%) was added into the photosensitive resin for preparing 3D printing slurry. Our results indicated that an optimized sintering condition includes the debinding rate (0.5°C/min), and temperature raising rate (5°C/min) and sintering temperature (1100°C) were proposed to sinter 45S5 bioceramic scaffolds. The amorphous 45S5 bioglass showed good crystallization after sintering, and the scaffold porous structure showed good integrity. Micropores were observed in the struts which interconnected with each other. Moreover, the porosities were tested as 57% and 45% with a uniform pore distribution. The shrinkage rate was about 10% during sintering process due to binder burning and crystallization shrinkage. The compressive strength of the sintered scaffold was 0.71 ± 0.048 MPa and 2.13 ± 0.054 MPa, respectively, which are consistent with the finite element mechanical analysis simulation results. In conclusion, the layered perforated 45S5 bioglass scaffold shows good mechanical properties and porosity, indicating that it could be a promising candidate for bone tissue engineering.

SrFe12O19-doped nano-layered double hydroxide/chitosan layered scaffolds with a nacre-mimetic architecture guide in situ bone ingrowth and regulate bone homeostasis.

Osteoporotic bone defects result from an imbalance in bone homeostasis, excessive osteoclast activity, and the weakening of osteogenic mineralization, resulting in impaired bone regeneration. Herein, inspired by the hierarchical structures of mollusk nacre, nacre exhibits outstanding high-strength mechanical properties, which are in part due to its delicate layered structure. SrFe12O19 nanoparticles and nano-layered double hydroxide (LDH) were incorporated into a bioactive chitosan (CS) matrix to form multifunctional layered nano-SrFe12O19-LDH/CS scaffolds. The compressive stress value of the internal ordered layer structure matches the trabecular bone (0.18 ​MPa). The as-released Mg2+ ions from the nano-LDH can inhibit bone resorption in osteoclasts by inhibiting the NFκB signaling pathway. At the same time, the as-released Sr2+ ions promote the high expression of osteoblast collagen 1 proteins and accelerate bone mineralization by activating the BMP-2/SMAD signaling pathway. In vivo, the Mg2+ ions released from the SrFe12O19-LDH/CS scaffolds inhibited the release of pro-inflammatory factors (IL-1β and TNF-α), while the as-released Sr2+ ions promoted osteoblastic proliferation and the mineralization of osteoblasts inside the layered SrFe12O19-LDH/CS scaffolds. Immunofluorescence for OPG, RANKL, and CD31, showed that stable vasculature could be formed inside the layered SrFe12O19-LDH/CS scaffolds. Hence, this study on multifunctional SrFe12O19-LDH/CS scaffolds clarifies the regulatory mechanism of osteoporotic bone regeneration and is expected to provide a theoretical basis for the research, development, and clinical application of this scaffold on osteoporotic bone defects.

Application of microcarrier technology in cartilage repairing: a review

Cartilage has poor self-recovery because of its characteristics of no blood vessels and high extracellular matrix. In clinical treatment, physical therapy or drug therapy is usually used for mild cartilage defects, and surgical treatment is needed for severe ones. In recent years, cartilage tissue engineering technology provides a new way for the treatment of cartilage defects. Compared with the traditional surgical treatment, cartilage tissue engineering technology has the advantages of small wound and good recovery. The application of microcarrier technology in the design of tissue engineering scaffolds further expands the function of scaffolds and promotes cartilage regeneration. This review summarized the main preparation methods and development of microcarrier technology in recent years. Subsequently, the properties and specific application scenarios of microcarriers with different materials and functions were introduced according to the materials and functions of microcarriers used in cartilage repair. Based on our research on osteochondral integrated layered scaffolds, we proposed an idea of optimizing the performance of layered scaffolds through microcarriers, which is expected to prepare bionic scaffolds that are more suitable for the structural characteristics of natural cartilage.

Particulate ECM biomaterial ink is 3D printed and naturally crosslinked to form structurally-layered and lubricated cartilage tissue mimics

Articular cartilage is a layered tissue with a complex, heterogeneous structure and lubricated surface which is challenging to reproduce using traditional tissue engineering methods. Three-dimensional printing techniques have enabled engineering of complex scaffolds for cartilage regeneration, but constructs fail to replicate the unique zonal layers, and limited cytocompatible crosslinkers exist. To address the need for mechanically robust, layered scaffolds, we developed an extracellular matrix particle-based biomaterial ink (pECM biomaterial ink) which can be extruded, polymerizes via disulfide bonding, and restores layered tissue structure and surface lubrication. Our cartilage pECM biomaterial ink utilizes functionalized hyaluronan (HA), a naturally occurring glycosaminoglycan, crosslinked directly to decellularized tissue particles (ø40–100 µm). We experimentally determined that HA functionalized with thiol groups (t-HA) forms disulfide bonds with the ECM particles to form a 3D network. We show that two inks can be co-printed to create a layered cartilage scaffold with bulk compressive and surface (friction coefficient, adhesion, and roughness) mechanics approaching values measured on native cartilage. We demonstrate that our printing process enables the addition of macropores throughout the construct, increasing the viability of introduced cells by 10%. The delivery of these 3D printed scaffolds to a defect is straightforward, customizable to any shape, and adheres to surrounding tissue.

Novel chitosan-poly(vinyl acetate) biomaterial suitable for additive manufacturing and bone tissue engineering applications

Chitosan, a biocompatible and biodegradable natural polymer, offers great promise as a biomaterial for tissue engineering applications. Chitosan scaffolds have previously been fabricated using additive manufacturing techniques, however, the use of crosslinkers, weak mechanical stability and structural resolution remain problematic. In this study Chitosan-PVAc biopolymer blends were prepared using a non-organic solvent that can prepare a three-dimensional printable biopolymer in less time than conventional methods. Prepared films were characterised using SEM, FTIR and thermogravimetric analysis. Additionally, the swelling properties, biodegradability and printability of the scaffolds were also studied. The fabricated films were biodegradable within a 3-week period and showed controllable swelling properties. Results indicated no toxicity and cells attached onto films. Additionally, hydrogels showed antibacterial activity against S. aureus, S. epidermidis and E.coli, which could potentially prevent implant related infections. Additive manufacturing simulation of PVAc composite 3% chitosan and PVAc composite 4% chitosan were able to produce a layered scaffold without using crosslinkers and therefore confirming printability. Cytocompabability were assessed using a resazurin assay and cell attachment. From these results, we concluded that the printable PVAc composite 3% chitosan and PVAc composite 4% chitosan biopolymer blends meet the requirements of a biomaterial and can potentially be used for biomedical implants.

Layer-specific stem cell differentiation in tri-layered tissue engineering biomaterials: Towards development of a single-stage cell-based approach for osteochondral defect repair.

Successful repair of osteochondral defects is challenging, due in part to their complex gradient nature. Tissue engineering approaches have shown promise with the development of layered scaffolds that aim to promote cartilage and bone regeneration within the defect. The clinical potential of implanting these scaffolds cell-free has been demonstrated, whereby cells from the host bone marrow MSCs infiltrate the scaffolds and promote cartilage and bone regeneration within the required regions of the defect. However, seeding the cartilage layer of the scaffold with a chondrogenic cell population prior to implantation may enhance cartilage tissue regeneration, thus enabling the treatment of larger defects. Here the development of a cell seeding approach capable of enhancing articular cartilage repair without the requirement for in vitro expansion of the cell population is explored. The intrinsic ability of a tri-layered scaffold previously developed in our group to direct stem cell differentiation in each layer of the scaffold was first demonstrated. Following this, the optimal chondrogenic cell seeding approach capable of enhancing the regenerative capacity of the tri-layered scaffold was demonstrated with the highest levels of chondrogenesis achieved with a co-culture of rapidly isolated infrapatellar fat pad MSCs (FPMSCs) and chondrocytes (CCs). The addition of FPMSCs to a relatively small number of CCs led to a 7.8-fold increase in the sGAG production over chondrocytes in mono-culture. This cell seeding approach has the potential to be delivered within a single-stage approach, without the requirement for costly in vitro expansion of harvested cells, to achieve rapid repair of osteochondral defects.

Preclinical assessment on neuronal regeneration in the injury-related microenvironment of graphene-based scaffolds

As the application of graphene nanomaterials gets increasingly attractive in the field of tissue engineering and regenerative medicine, the long-term evaluation is necessary and urgent as to their biocompatibility and regenerative capacity in different tissue injuries, such as nerve, bone, and heart. However, it still remains controversial about the potential biological effects of graphene on neuronal activity, especially after severe nerve injuries. In this study, we establish a lengthy peripheral nerve defect rat model and investigate the potential toxicity of layered graphene-loaded polycaprolactone scaffold after implantation during 18 months in vivo. In addition, we further identify possible biologically regenerative effects of this scaffold on myelination, axonal outgrowth, and locomotor function recovery. It is confirmed that graphene-based nanomaterials exert negligible toxicity and repair large nerve defects by dual regulation of Schwann cells and astroglia in the central and peripheral nervous systems. The findings enlighten the future of graphene nanomaterial as a key type of biomaterials for clinical translation in neuronal regeneration.

Effects of PbS quantum dots layer and different light scattering films on the photovoltaic performance of double passivated PbS, CdS and CdSe quantum dots sensitized solar cells

In this research, two novel multi-layer photoelectrodes were fabricated and applied in quantum dot sensitized solar cells (QDSCs). The double layer scaffolds were composed of a TiO2 nanocrystalline sub-layer covered with an over-grown TiO2 nanorods (NRs) or ex-synthesized TiO2 hollow spheres (HSs) film. The light sensitization was carried out by deposition of separated PbS, CdS and CdSe quantum dots (QDs) layers. Finally, two electron blocking/passivating films of ZnS and SiO2 were formed for better photovoltaic (PV) performance. The syntheses of TiO2 nanocrystals (NCs), HSs and NRs were performed and tuned through different hydrothermal methods. The depositions of the PbS, CdS and ZnS layers were carried out by conventional successive ionic layer adsorption and reaction (SILAR) process. The CdSe and SiO2 films were also formed using a modified, effective chemical bath deposition (CBD) and sol–gel techniques, respectively. The PbS sensitizing film was additionally utilized for higher PV efficiency and the number of deposition cycles(X) was altered for the purpose of optimization. For the cell with novel TiO2NCs/TiO2NRs/PbS(X)/CdS/CdSe/ZnS/SiO2, X = 0–3, photoanode, the highest efficiency was about 5.5% and achieved for X = 2. This power conversion efficiency (PCE) was enhanced about 28% compared to that of the PbS free photoelectrode. The other improved TiO2 NCs/TiO2HSs/PbS(X)/CdS/CdSe/ZnS/SiO2, X = 0–3, photoanode was also utilized with a light scattering HSs film. The maximum efficiency was achieved about 6.5% for the extra PbS(2) sensitizing layer. This PCE was increased about 20% compared to the PbS free photoelectrode and 51% compared to that of the QDSC with the PbS free, NRs included photoanode. The highest efficiency was attributed to the co-sensitization and optimized PbS sensitizing layer together with the effective light scattering and utilization of double passivating layers.

Biphasic CK2.1-coated β-glycerophosphate chitosan/LL37-modified layered double hydroxide chitosan composite scaffolds enhance coordinated hyaline cartilage and subchondral bone regeneration

• We fabricated peptide-modified bilayered scaffold for osteochondral defect. • Superficial CK2.1@GC could realize hyaline cartilage regeneration. • Bottom biomimetic LL37@LC could stimulate subchondral bone formation. Articular osteochondral defect is commonly seen after trauma or in patients with degenerative osteoarthritis. Currently, the treatment of osteochondral lesions is still challenging due to the limited healing ability of cartilage as well as the poorly effective traditional method. In this study, we fabricated a bilayer peptide-loaded scaffold consisting of CK2.1 coated β-glycerophosphate/chitosan (CK2.1@GC) for cartilage regeneration and LL37 modified layered double hydroxide/chitosan (LL37@LC) for subchondral bone regeneration, designed in an integrated strategy involving mesenchymal stem cells (MSCs) recruitment and multifunctional therapeutic biomaterials of bone regeneration and vascularization. The lower LC scaffold is highlighted with a biomimetic lamellar structural design, providing a novel platform for the integration of newborn bone tissue and blood vessels. In vitro results showed our peptide-loaded bilayer scaffold could induce the MSCs to differentiate into chondrocytes and osteoblasts in different layers respectively. LL37@LC could also attract MSCs and promote vasculogenesis in vitro. Meanwhile, osteochondral defect could be efficiently repaired by this peptide-modified bilayered scaffold in the rabbit model. This study demonstrated that our composite scaffold could smartly enhance the repair of hyaline cartilage and subchondral bone defect, which shed light on a novel therapeutic strategy for the intervention of patients with articular osteochondral defect.