Hierarchical Scaffolds Research Articles

3D Printed Hierarchical Porous Poly(ε-caprolactone) Scaffolds from Pickering High Internal Phase Emulsion Templating.

In the realm of biomaterials, particularly bone tissue engineering, there has been a great increase in interest in scaffolds with hierarchical porosity and customizable multifunctionality. Recently, the three-dimensional (3D) printing of biopolymer-based inks (solutions or emulsions) has gained high popularity for fabricating tissue engineering scaffolds, which optimally satisfies the desired properties and performances. Herein, therefore, we explore the fabrication of 3D printed hierarchical porous scaffolds of poly(ε-caprolactone) (PCL) using the water-in-oil (w/o) Pickering PCL high internal phase emulsions (HIPEs) as the ink in 3D printer. The Pickering PCL HIPEs stabilized using hydrophobically modified nanoclay comprised of aqueous poly(vinyl alcohol) (PVA) as the dispersed phase. Rheological measurements suggested the shear thinning behavior of Pickering HIPEs having a dispersed droplet diameter of 3-25 μm. The pore morphology resembling the natural extracellular matrix and the mechanical properties of scaffolds were customized by tuning the emulsion composition and 3D printing parameters. In vitro biomineralization and drug release studies proved the scaffolds' potential in developing the apatite-rich bioactive interphase and controlled drug delivery, respectively. During in vitro osteoblast (MG63) growth experiments for up to 7 days, good adhesion and proliferation on PCL scaffolds confirmed their cytocompatibility, assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) analysis. This study suggests that the assembly of HIPE templates and 3D printing is a promising approach to creating hierarchical porous scaffolds potentially suitable for bone tissue engineering and can be stretched to other biopolymers as well.

Extrafibrillarly Demineralized Dentin Matrix for Bone Regeneration.

Dentin is a natural extracellular matrix, but its availability in bone grafting and tissue engineering applications is underestimated due to a lack of proper treatment. In this study, the concept of extrafibrillar demineralization is introduced into the construction of dentin-derived biomaterials for bone regeneration for the first time. Calcium chelating agents with large molecular weights are used to selectively remove the extrafibrillar apatite minerals without disturbing the intrafibrillar minerals within dentin collagen, resulting in the formation of an extrafibrillarly demineralized dentin matrix (EDM). EDM with distinctive nanotopography and bone-like mechanical properties is found to significantly promote cell adhesion, migration, and osteogenic differentiation in vitro while enhancing in vivo bone healing of rat calvarial defects. The outstanding osteogenic performance of EDM is further confirmed to be related to the activation of the focal adhesion-cytoskeleton-nucleus mechanotransduction axis. Overall, this study shows that extrafibrillar demineralization of dentin has great potential to produce hierarchical collagen-based scaffolds for bone regeneration, and this facile top-down fabrication method brings about new ideas for the biomedical application of naturally derived bioactive materials.

Hierarchical hydrogel scaffolds with a clustered and oriented structure.

Hydrogel scaffolds play a critical role in tissue engineering due to their hydrophilic network structure and good biocompatibility. Constructing anisotropic scaffolds geometrically similar to injured tissues is conducive to promoting the generation of tissue and organ equivalents, or to guiding and enhancing the regeneration of injured tissues. In this study, we developed polyvinyl alcohol (PVA)/alginate hierarchical hydrogel scaffolds with a clustered and oriented structure using a method that combines directional freezing and drying under stretching. Our hydrogel scaffolds with an adjustable modulus (50 kPa-20 MPa) can match different types of injured tissues. The clustered and oriented structure successfully guided the alignment and orientation of fibroblasts and chondrocytes. This work provides a new idea for constructing hydrogels with hierarchical and anisotropic microstructures, which have promising applications in tissue regeneration.

Hierarchically patterned protein scaffolds with nano-fibrillar and micro-lamellar structures modulate neural stem cell homing and promote neuronal differentiation.

Biophysical factors are essential in cell survival and behaviors, but constructing a suitable 3D microenvironment for the recruitment of stem cells and exerting their physiological functions remain a daunting challenge. Here, we present a novel silk fibroin (SF)-based fabrication strategy to develop hierarchical microchannel scaffolds for biomimetic nerve microenvironments in vitro. We first modulated the formation of SF nanofibers (SFNFs) that mimic the nanostructures of the native extracellular matrix (ECM) by using graphene oxide (GO) nanosheets as templates. Then, SFNF-GO systems were shaped into 3D porous scaffolds with aligned micro-lamellar structures by freeze-casting. The interconnected microchannels successfully induced cell infiltration and migration to the SFNF-GO scaffolds' interior. Meanwhile, the nano-fibrillar structures and the GO component significantly induced neural stem cells (NSCs) to differentiate into neurons within a short timeframe of 14 d. Importantly, these 3D hierarchical scaffolds induced a mild inflammatory response, extensive cell recruitment, and effective stimulation of NSC neuronal differentiation when implanted in vivo. Therefore, these SFNF-GO lamellar scaffolds with distinctive nano-/micro-topographies hold promise in the fields of nerve injury repair and regenerative medicine.

Biomimetic three-layer hierarchical scaffolds for efficient water management and cell recruitment

Taking inspiration from the structures of roots, stems and leaves of trees in nature, a biomimetic three-layered scaffold was designed for efficient water management and cell recruitment. Using polycaprolactone (PCL) and polyacrylonitrile (PAN) as raw materials, radially oriented nanofiber films and multistage adjustable nanofiber films were prepared through electrospinning technology as the base skin-friendly layer (roots) and middle unidirectional moisture conductive material (stems), the porous polyurethane foam was integrated as the outer moisturizing layer (leaves). Among which, radially oriented nanofiber films could promote the directional migration of fibroblasts and induce cell morphological changes. For the spatially hierarchically nanofiber films, the unidirectional transport of liquid was effectively realized. While the porous polyurethane foam membrane could absorb 9 times its weight in biofluid and retain moisture for up to 10 h. As a result, the biomimetic three-layered scaffolds with different structures can promote wound epithelization and drain biofluid while avoiding wound inflammation caused by excessive biofluid, which is expected to be applied in the field of skin wounds.

Hybrid 3D Printed and Electrospun Multi-Scale Hierarchical Polycaprolactone Scaffolds to Induce Bone Differentiation.

Complex scaffolds composed of micro- and nano-structures are a key target in tissue engineering and the combination of sequential 3D printing and electrospinning enables the fabrication of these multi-scale structures. In this work, dual 3D printed and electrospun polycaprolactone (PCL) scaffolds with multiple mesh layers were successfully prepared. The scaffold macro- and micro-porosity were assessed by optical and scanning electron microscopy, showing that electrospun fibers formed aligned meshes within the pores of the scaffold. Consequently, the hydrophilicity of the scaffold increased with time, enhancing cell adhesion and growth. Additionally, compression tests in back and forth cycles demonstrated a good shape recovery behavior of the scaffolds. Biological results indicated that hybrid PCL scaffolds are biocompatible and enable a correct cell culture over time. Moreover, MC3T3-E1 preosteoblast culture on the scaffolds promoted the mineralization, increased the alkaline phosphatase (ALP) activity and upregulated the expression of early and late osteogenic markers, namely ALP and osteopontin (OPN), respectively. These results demonstrate that the sequential combination of 3D printing and electrospinning provides a facile method of incorporating fibers within a 3D printed scaffold, becoming a promising approach towards multi-scale hierarchical scaffolds capable of guiding the osteogenic differentiation.

Hierarchical Macro-Mesoporous Silica Monolithic Tablets as a Novel Dose-Structure-Dependent Delivery System for the Release of Confined Dexketoprofen.

This study reports the application of hierarchical porous monoliths as carriers for controlled and dose-adjustable release of model pharmaceutical (dexketoprofen, DEX). The synthesis and detailed characterization of the hierarchical porous scaffolds are provided before and after the adsorption of three doses of DEX─a widely used nonsteroidal anti-inflammatory drug. The drug incorporated in the mesopores of silica was stabilized in an amorphous state, while the presence of macropores provided sufficient space for drug crystallization as we demonstrated via a combination of powder X-ray diffraction, differential scanning calorimetry, and imaging techniques (scanning electron microscopy and EDX analysis). Drug release from silica matrices was tested, and a mechanistic model of this release based on the Fick diffusion equation was proposed. The hierarchical structure of the carrier, due to the presence of micrometric macropores and nanometric mesopores, turned out to be critical for the control of the drug phase and drug release from the monoliths. It was found that at low drug content, the presence of an amorphous component in the pores promoted the rapid release of the drug, while at higher drug contents, the presence of macropores favored the crystallization of DEX, which naturally slowed down its release. Both the hierarchical porous structure and the control of the drug phase (amorphous and/or crystalline) were proven important for adjustable (fast or prolonged) release kinetics, desirable for effective pharmacotherapy and patient compliance. Therefore, the developed materials may serve as a versatile formulation platform for the smart manipulation of drug release kinetics.

Controlling the hierarchical microstructure of bioceramic scaffolds by 3D printing of emulsion inks

Mechanical and biological properties constitute the most fundamental requirements for bone tissue engineering (BTE) scaffolds. Nonetheless, existing fabrication strategies find it difficult to prepare highly porous BTE scaffolds for improved biological properties while also preserving sufficient mechanical properties that are compatible with the natural bone. Inspired by the hierarchical porous materials in Nature, hierarchical porous BTE scaffolds can achieve a combination of superior mechanical efficiency and biological functions. With this in mind, this study reports the fabrication of hierarchical porous hydroxyapatite (hpHA) scaffolds by 3D printing of emulsion inks. The scaffolds exhibit high porosity up to 73.7%, featuring 3D printed macropores of 300 – 400 µm and emulsion templated microporosity of < 20 µm. Via formulation of the emulsion inks, such as varying the oil volume and adding Pluronic® F-127, this process demonstrates effective control of the microporosity and pore morphology of the scaffolds. The scaffolds are mechanically compatible with the natural cancellous bone, with compressive strength in the range of 1.41 – 7.84 MPa and Young’s modulus of 57.3 – 304 MPa. Furthermore, the elastic admissible strain (EAS) and specific energy absorption (SEA) of the hpHA scaffolds can be increased up to 4.4% and 1.22 kJ/kg, respectively, indicating greatly enhanced mechanical performances owing to the hierarchical porous structure. Meanwhile, improved cell attachment, spreading and proliferation are observed in these scaffolds with their additional microporosity. Hence, the hpHA scaffolds in this study show great potential in BTE applications, and the reported process of 3D printing of emulsion inks is a promising fabrication strategy for further optimization of highly porous BTE scaffolds.

Porous transition metal oxide scaffold implanted with interpenetrated catalytic network enabling polysulfides restricted and dendrite free Lithium–Sulfur batteries

The exploration of porous polar hosts with good structural stability, high catalytic activity, lithophilic nature, and high-conductivity is desirable to solve the dilatory polysulfide redox kinetics and the uncontrolled lithium dendrite growth for efficient and stable lithium–sulfur (Li–S) batteries. Herein, a novel hierarchical metal oxide-based scaffold is developed, in which N-doped carbon nanotubes encapsulated with Co nanoparticles are in-situ implanted within three-dimensional ordered macroporous Co-doped TiO2 (Co@NCNTs/Co-TiO2) as efficient hosts for both sulfur and Li electrodes. Benefiting from the excellent stability of polar Co-TiO2 skeleton, high catalytic activity and lithophilic properties of Co nanoparticles, and high-conductivity of the inter-penetrated NCNTs, the polysulfide conversion kinetics are dramatically boosted, and the dendrite-free lithium electrochemistry is simultaneously accomplished. Cooperatively, the Co@NCNTs/Co-TiO2/Li ‖ Co@NCNTs/Co-TiO2/S full cell expresses high rate capability of 879.66 mAh g−1 at 5C, as well as super cycling stability with a low capacity decay rate of about 0.033 % after 1000 cycles at 3C. Additionally, Li–S pouch cell assembled by Co@NCNTs/Co-TiO2/Li anode and Co@NCNTs/Co-TiO2/S cathode also exhibits a remarkable discharge capacity of 1020.4 mAh g−1 with sulfur loading even reaching 4.5 mg cm−2 after 200 cycles. The present work reveals an effective strategy for developing advanced Li–S batteries dual-functional electrodes.

Bioinspired stretchable helical nanofiber yarn scaffold for locomotive tissue dynamic regeneration

<h2>Summary</h2> Simulating the microstructure and mechanical properties of natural tissues to achieve rapid tissue regeneration and protect cells under strain during body movement is a giant challenge in locomotive tissue engineering. Here, we built a hierarchical helical scaffold with high stretchability, which not only structurally resembles natural tissues but also matches their non-affine deformation mechanical properties. The cells on this scaffold can maintain high viability under cyclic strains, because the non-planar motion of coil structures mitigates the local maximum strain during stretching. Moreover, the <i>in vivo</i> experiments demonstrated that the scaffold affords a stable structural and mechanical microenvironment for cell growth and tissue morphogenesis. This helical scaffold breaks the inherent mindset of fixation repairing and makes it possible for reconstruction of the defective tissue even in moderate motion. The study proposes a new thinking about construction of stretchable scaffolds with superior mechanical properties for repairing locomotive tissue injuries.

Osteoimmunity‐Regulating Biomimetically Hierarchical Scaffold for Augmented Bone Regeneration (Adv. Mater. 36/2022)

Osteoimmunity‐Regulating Biomimetically Hierarchical Scaffold for Augmented Bone Regeneration (Adv. Mater. 36/2022)

In vitro Evaluation of a 20% Bioglass-Containing 3D printable PLA Composite for Bone Tissue Engineering.

Three-dimensional (3D) printing is considered a key technology in the production of customized scaffolds for bone tissue engineering. In a previous work, we developed a 3D printable, osteoconductive, hierarchical organized scaffold system. The scaffold material should be osteoinductive. Polylactic acid (PLA) (polymer)/Bioglass (BG) (mineral/ion source) composite materials are promising. Previous studies of PLA/BG composites never exceed BG fractions of 10%, as increase of bioactive BG component negatively affects the printability of the composite material. Here, we test a novel, 3D printable PLA/BG composite with BG fractions up to 20% for its biological activity in vitro. PLA/BG filaments suitable for microstructure 3D printing were spun and the effect of different BG contents (5%, 10%, and 20%) in this material on mesenchymal stem cell (MSC) activity was tested in vitro. Our results showed that all tested composites are biocompatible. MSC cell adherence and metabolic activity increase with increasing BG content. The presence of BG component in scaffold has only slight effect on osteogenic gene expression, but it has significant suppressive effect on the expression of inflammatory genes in MSC. In addition, the material did not provoke any significant inflammatory response in whole-blood stimulation assay. The results show that by increasing the BG content, the bioactivity can be further enhanced.

A biomimetic Janus delignified wood membrane with asymmetric wettability prepared by thiol-ol chemistry for unidirectional water transport and selective oil/water separation

Inspired by the amazing intelligent water manipulation behavior of cactus, spiders, and desert beetles, tremendous efforts have been devoted to developing intelligent Janus membrane materials with asymmetric wettability for unidirectional water transport and selective water/oil separation. However, the remaining challenges include tedious procedures, harsh conditions, expensive devices, and scaling-up problems. Inspired by the oriented tubular porosity and hierarchical scaffold of wood, biomimetic Janus wood membranes with asymmetric wettability were prepared by direct ultraviolet-induced thiol-ol chemistry. The delignified wood membranes were first prepared by the partial removal of hemicellulose and lignin from the natural balsa wood; Subsequently, an octadecanethiol/ethanol solution was sprayed onto the one side of the delignified wood membrane surfaces. After ultraviolet irradiation under ambient conditions, Janus wood membranes with asymmetric wettability were successfully prepared. The resultant Janus wood membranes exhibited unidirectional water-transport ability and selective oil/water separation; both heavy oil/water and light oil/water mixtures could be separated by merely changing the orientation of the membrane. In addition, the Janus wood membranes showed excellent separation efficiency and recyclability. This novel, facile, scalable, and low-cost strategy for preparing Janus membranes holds great potential for applications in several fields, such as droplet manipulation, multi-liquid separation, purification of industrial wastewater, and microfluidics.

3D printing of hierarchically porous monolithic TS‐1 catalyst for one-pot synthesis of ethylene glycol

Structured monolithic catalysts have attracted increasing attention in the petrochemical industry due to their advantages of high heat and mass transfer rate, easy scale-up, and reusability. Herein, we put forward a strategy for one-step preparation of SiO2-based monolithic TS-1 catalysts with optimal hierarchical scaffolds by combining the flow field simulation of the reactor and 3D printing technology. Tunable hierarchical porosity from nano to micro scales, suitable pore characteristics, and numerous active sites have been obtained by innovatively combining the spherical porous structure of TS-1/SiO2 material, direct ink writing (DIW) and post-sintering processes. Combined with computational fluid dynamics (CFD) analysis, the effects of different channel offset angles, axial and radial channel sizes on the 3D printed monolithic TS-1 in the catalytic reaction of one-step oxidation of ethylene to ethylene glycol (EG) were verified. 3D-printed monolithic TS-1 catalysts exhibited superior crush strengths (135.11 N/cm) and extraordinary catalytic efficiency, in which the yield of EG reached 82.7%, and the utilization of hydrogen peroxide reached 85.3%. Moreover, the 3D printed TS-1 monolith maintained high catalytic performance over 5 reusable cycles, which solved the problem that traditional catalysts are difficult to be manufactured, separated, and recycled, and presented considerable prospects in reactions requiring fluid agitation.

Osteoimmunity-Regulating Biomimetically Hierarchical Scaffold for Augmented Bone Regeneration.

Engineering a proper immune response following biomaterial implantation is essential to bone tissue regeneration. Herein, a biomimetically hierarchical scaffold composed of deferoxamine@poly(ε-caprolactone) nanoparticles (DFO@PCL NPs), manganese carbonyl (MnCO) nanosheets, gelatin methacryloyl hydrogel, and a polylactide/hydroxyapatite (HA) matrix is fabricated to augment bone repair by facilitating the balance of the immune system and bone metabolism. First, a 3D printed stiff scaffold with a well-organized gradient structure mimics the cortical and cancellous bone tissues; meanwhile, an inside infusion of a soft hydrogel further endows the scaffold with characteristics of the extracellular matrix. A Fenton-like reaction between MnCO and endogenous hydrogen peroxide generated at the implant-tissue site triggers continuous release of carbon monoxide and Mn2+ , thus significantly lessening inflammatory response by upregulating the M2 phenotype of macrophages, which also secretes vascular endothelial growth factor to induce vascular formation. Through activating the hypoxia-inducible factor-1α pathway, Mn2+ and DFO@PCL NP further promote angiogenesis. Moreover, DFO inhibits osteoclast differentiation and synergistically collaborates with the osteoinductive activity of HA. Based on amounts of data in vitro and in vivo, strong immunomodulatory, intensive angiogenic, weak osteoclastogenic, and superior osteogenic abilities of such an osteoimmunity-regulating scaffold present a profound effect on improving bone regeneration, which puts forward a worthy base and positive enlightenment for large-scale bone defect repair.

Formation of poly(ε‐caprolactone)‐embedded bioactive nanoparticles/collagen hierarchical scaffolds with the designed and customized porous structures

AbstractThe biodegradable and bioactive bioscaffolds with suitable hierarchical structure, customized shape, and mechanical performance have great potential for biomedical applications especially in tissue engineering field. However, controllable and facile preparation of the related porous scaffolds remains obvious challenge. In this study, poly(ε‐caprolactone) (PCL)‐embedded hydroxyapatite (HAP) nanoparticles/collagen hierarchical scaffolds are facilely prepared basing on 3D printing of the pre‐crosslinked oil in water type Pickering high internal phase emulsion (HIPE) hydrogel. To be specific, in the HAP nanoparticle stabilized Pickering HIPEs, the aqueous phase contains collagen and genipin, and the oil phase is dichloromethane solution of PCL. After the pre‐crosslinking of aqueous phase, the prepared Pickering HIPE turns into emulsion hydrogel with high viscosity and shear thinning characteristics, which can be individually printed and then freeze dried to produce hierarchical scaffolds with the designed structures. The related multiscale pore structures are composed of mm‐scale macropores and μm‐scale micropores, and the related porosity is higher than 84%. Increasing PCL content obviously enhances the compression stress of scaffolds, particularly the compressive stress of porous scaffold prepared with PCL content of 14 w/v% is about 9 times as large as that of porous scaffold without PCL. The results of in vitro mineralization and cell culture assay show that the porous scaffolds have favorable apatite formation ability and biocompatibility. Thus, the prepared hierarchical scaffolds with the designed structures, customized shape and adjustable performance are promising potential applications in bone tissue engineering.

The Synergy of Biomimetic Design Strategies for Tissue Constructs

AbstractThe regeneration and repair of complex structures, interfaces, and mechanical properties present in natural tissues remains a challenge. To move beyond simplified tissue engineered constructs, nature is a source of inspiration for complex, hierarchical scaffold designs. Recent advances in additive manufacturing allow for increasingly complex fabrication of architectures that better mimic the multiscale structure‐function relationship found in natural tissues. In this review, scaffold‐based and scaffold‐free approaches and the synergistic use of fabrication technologies (two things make a third) to produce more biomimetic implants are described. Recent advanced scaffold designs such as auxetic mechanical metamaterials and induced fibrillar alignment are highlighted. Next, the pre‐programmed assembly of spheroids, tissue strands, and other modular building blocks without the need for permanent exogenous scaffold support are discussed. Furthermore, the application of hybridized manufacturing processes to fabricate hierarchical functional constructs is outlined for the osteochondral unit, vascular grafts, and peripheral nerves.

Seamless route of self-assembly and 3D printing to fabricate hierarchical mesoporous bioactive glass scaffold for customized bone regeneration with enhanced efficacy

Mesoporous bioactive glass (MBG) was one of the most promising bone regenerative materials for its well-acknowledged bioactivity, biodegradability, and osteoinductivity, as well as its potential for drug delivery. However, it remained a challenge to fabricate MBG scaffold with precisely controllable macro-structure and robust mechanical strength meanwhile to maintain uncompromised composition and mesoporosity. Herein, a fabricating route incorporating self-assembly and 3D printing (SAP) via acryloylating F127 (mesoporous template) was proposed and successfully realized directly printing MBG sol into hierarchical macro-/mesoporous SAP-MBG scaffold with compact and integral structure. Compared to traditional polyurethane (PU) templated MBG scaffold, SAP-MBG scaffold exhibited significantly enhanced mechanical strength meanwhile maintained non-composite component and mesoporous structure. SAP-MBG presented improved macropore interconnectivity and faster calcium dissolution, resulting in superior cellular penetration, in vitro osteogenic performances and in vivo bone regenerative efficacy in a critical-size rat cranial defect model. The SAP fabricating route represented an available approach to overcome the drawbacks of conventional manufacturing methods and realized individualized manufacturing of MBG scaffold. The synthetic design of this study might be extended to the fabricating process improvement of other mesoporous inorganic materials and shed light on future clinical translation of MBG scaffold in bone regeneration.

Construction of a binder-free non-enzymatic glucose sensor based on Cu@Ni core–shell nanoparticles anchored on 3D chiral carbon nanocoils-nickel foam hierarchical scaffold

Bimetallic nanostructures composited with carbonaceous materials are the potential contenders for quantitative glucose measurement owing to their unique nanostructures, high biomimetic activity, synergistic effects, good conductivity and chemical stability. In the present work, chemical vapors deposition technique has been employed to grow 3D carbon nanocoils (CNCs) with a chiral morphology on hierarchical macroporous nickel foam (NF) to get a CNCs/NF scaffold. Following, bimetallic Cu@Ni core–shell nanoparticles (CSNPs) are effectively coupled with this scaffold through a facile solvothermal route in order to fabricate a binder-free novel Cu@Ni CSNPs/CNCs/NF hybrid nanostructure. The constructed free-standing 3D hierarchical composite electrode guarantees highly efficient glucose redox activity due to core–shell synergistic effects, enhanced electrochemical active surface area, excellent electrochemical stability, improved conductivity with better ion diffusivity and accelerated reaction kinetics. Being a non-enzymatic glucose sensor, this electrode achieves highly swift response time of 0.1 s, ultra-high sensitivity of 6905 μA mM−1 cm−2, low limit of detection of 0.03 μM along with potential selectivity and good storage stability. Moreover, the proposed sensor is also tested successfully for the determination of glucose concentration in human serum samples under good recovery ranging from 96.6 to 102.1 %. The 3D Cu@Ni CSNPs/CNCs/NF composite electrode with unprecedented catalytic performance can be utilized as an ideal biomimetic catalyst in the field of non-enzymatic glucose sensing.

Blood-Vessel-Inspired Hierarchical Trilayer Scaffolds: PCL/Gelatin-Driven Protein Adsorption and Cellular Interaction.

Fabrication of scaffolds with hierarchical structures exhibiting the blood vessel topological and biochemical features of the native extracellular matrix that maintain long-term patency remains a major challenge. Within this context, scaffold assembly using biodegradable synthetic polymers (BSPs) via electrospinning had led to soft-tissue-resembling microstructures that allow cell infiltration. However, BSPs fail to exhibit the sufficient surface reactivity, limiting protein adsorption and/or cell adhesion and jeopardizing the overall graft performance. Here, we present a methodology for the fabrication of three-layered polycaprolactone (PCL)-based tubular structures with biochemical cues to improve protein adsorption and cell adhesion. For this purpose, PCL was backbone-oxidized (O-PCL) and cast over a photolithography-manufactured microgrooved mold to obtain a bioactive surface as demonstrated using a protein adsorption assay (BSA), Fourier transform infrared spectroscopy (FTIR) and calorimetric analyses. Then, two layers of PCL:gelatin (75:25 and 95:5 w/w), obtained using a novel single-desolvation method, were electrospun over the casted O-PCL to mimic a vascular wall with a physicochemical gradient to guide cell adhesion. Furthermore, tensile properties were shown to withstand the physiological mechanical stresses and strains. In vitro characterization, using L929 mouse fibroblasts, demonstrated that the multilayered scaffold is a suitable platform for cell infiltration and proliferation from the innermost to the outermost layer as is needed for vascular wall regeneration. Our work holds promise as a strategy for the low-cost manufacture of next-generation polymer-based hierarchical scaffolds with high bioactivity and resemblance of ECM’s microstructure to accurately guide cell attachment and proliferation.