Core-shell Electrospun Research Articles

A Review on Advances and Challenges in Core-Shell Scaffolds for Bone Tissue Engineering: Design, Fabrication, and Clinical Translation.

This review explores core-shell scaffolds in bone tissue engineering, highlighting their osteoconductive and osteoinductive properties critical for bone growth and regeneration. Key design factors include material selection, porosity, mechanical strength, biodegradation kinetics, and bioactivity. Electrospun core-shell nanofibrous scaffolds demonstrate potential in delivering therapeutic agents and enhancing bone regeneration. Critical characterization techniques include structural, surface, chemical composition, mechanical, and degradation analyses. Scaling up production poses challenges, addressed by innovative electrospinning techniques. Future research focuses on regulatory and commercial considerations, while exploring advanced materials and fabrication methods to optimize scaffold performance for improved clinical outcomes.

Fabrication and characterization of electrospun core-shell nanofibers of bilayer zein/pullulan emulsions crosslinked by genipin

In this study, the electrospun core-shell nanofibers of zein/pullulan stabilized bilayer emulsions before and after genipin crosslinking were fabricated. The experimental results indicated that the addition of pullulan increased the apparent viscosity and elastic modulus of the bilayer emulsions, which was further increased after the chemical crosslinking of genipin. The nanofiber diameter increased from 102.9 nm to 169.9 nm with the increasing ratio of pullulan, but increased significantly to a range of 405.6–708.0 nm after genipin crosslinking. The electrospun nanofiber films of crosslinked emulsions had higher thermal stability and stronger water stability. The FTIR result proved the existence of hydrogen bond interaction between the zein, pullulan, and genipin molecules. In addition, before and after crosslinking, the encapsulation efficiency of electrospun fiber films for camellia oil was >77.68 %, and the maximum encapsulation efficiency could reach 87.94 %, and there was no significant change during the 7-day storage period, showing good stability. These research results can provide a theoretical basis for the encapsulation of hydrophobic active substances in zein-based emulsion electrospun core-shell nanofibers.

Synergistic Effects of Radical Distributions of Soluble and Insoluble Polymers within Electrospun Nanofibers for an Extending Release of Ferulic Acid.

Polymeric composites for manipulating the sustained release of an encapsulated active ingredient are highly sought after for many practical applications; particularly, water-insoluble polymers and core-shell structures are frequently explored to manipulate the release behaviors of drug molecules over an extended time period. In this study, electrospun core-shell nanostructures were utilized to develop a brand-new strategy to tailor the spatial distributions of both an insoluble polymer (ethylcellulose, EC) and soluble polymer (polyvinylpyrrolidone, PVP) within the nanofibers, thereby manipulating the extended-release behaviors of the loaded active ingredient, ferulic acid (FA). Scanning electron microscopy and transmission electron microscopy assessments revealed that all the prepared nanofibers had a linear morphology without beads or spindles, and those from the coaxial processes had an obvious core-shell structure. X-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopic tests confirmed that FA had fine compatibility with EC and PVP, and presented in all the nanofibers in an amorphous state. In vitro dissolution tests indicated that the radical distributions of EC (decreasing from shell to core) and PVP (increasing from shell to core) were able to play their important role in manipulating the release behaviors of FA elaborately. On one hand, the core-shell nanofibers F3 had the advantages of homogeneous composite nanofibers F1 with a higher content of EC prepared from the shell solutions to inhibit the initial burst release and provide a longer time period of sustained release. On the other hand, F3 had the advantages of nanofibers F2 with a higher content of PVP prepared from the core solutions to inhibit the negative tailing-off release. The key element was the water permeation rates, controlled by the ratios of soluble and insoluble polymers. The new strategy based on core-shell structure paves a way for developing a wide variety of polymeric composites with heterogeneous distributions for realizing the desired functional performances.

Core-shell electrospun polycaprolactone nanofibers, loaded with rifampicin and coated with silver nanoparticles, for tissue engineering applications

In the field of tissue engineering, the use of core-shell fibers represents an advantageous approach to protect and finely tune the release of bioactive compounds with the aim to regulate their efficacy. In this work, core-shell electrospun polycaprolactone nanofiber-based membranes, loaded with rifampicin and coated with silver nanoparticles, were developed and characterized. The membranes are composed by randomly oriented nanofibers with a homogeneous diameter, as demonstrated by scanning electron microscopy (SEM). An air-plasma treatment was applied to increase the hydrophilicity of the membranes as confirmed by contact angle measurements. The rifampicin release from untreated and air-plasma treated membranes, evaluated by UV spectrophotometry, displayed a similar and constant over-time release profile, demonstrating that the air-plasma treatment does not degrade the rifampicin, loaded in the core region of the nanofibers. The presence and the distribution of silver nanoparticles on the nanofiber surface were investigated by SEM and Energy Dispersive Spectroscopy. Moreover, SEM imaging demonstrated that the produced membranes possess a good stability over time, in terms of structure maintenance. The developed membranes showed a good biocompatibility towards murine fibroblasts, human osteosarcoma cells and urotheliocytes, reveling the absence of cytotoxic effects. Moreover, doble-functionalized membranes inhibit the growth of E. coli and S. aureus. Thanks to the possibilities offered by the coaxial electrospinning, the membranes here proposed are promising for several tissue engineering applications.

Functional electrospun polylactic acid core-shell thermochromic fibers with modified cellulose nanocrystals for enhanced temperature-responsive applications

Core-shell electrospun fibers with thermochromic materials are suitable for temperature sensing due to their customizable properties. However, the beneficial effect of bio-based thermochromic fibers incorporating sustainable nanomaterials needs to be further demonstrated, especially regarding their thermal stability and mechanical properties. In this study, core-shell structured nanofibers were produced through a co-axial electrospinning process using polylactic acid (PLA) and surface-modified cellulose nanocrystals (mCNCs) as the shell, and crystal violet lactone (CVL), bisphenol A, and 1-dodecanol as the core. Chemical characterization confirmed the successful grafting of vinyl siloxane within mCNCs, enhancing CNC dispersion in the PLA matrix. The thermochromic fibers exhibited smooth, uniform surfaces, with minimal impact of mCNCs on the glass transition temperature (Tg). Compared with neat electrospun PLA fibers, mCNC-added fibers showed improved thermal stability. Although the core material negatively affected mechanical properties, mCNCs enhanced tensile strength and Young’s modulus. The fibers demonstrated rapid and sensitive responses to temperature changes from 0 to 20 ˚C, indicating their potential as effective temperature sensors with improved properties.

Wound Dressing with Electrospun Core-Shell Nanofibers: From Material Selection to Synthesis.

Skin, the largest organ of the human body, accounts for protecting against external injuries and pathogens. Despite possessing inherent self-regeneration capabilities, the repair of skin lesions is a complex and time-consuming process yet vital to preserving its critical physiological functions. The dominant treatment involves the application of a dressing to protect the wound, mitigate the risk of infection, and decrease the likelihood of secondary injuries. Pursuing solutions for accelerating wound healing has resulted in groundbreaking advancements in materials science, from hydrogels and hydrocolloids to foams and micro-/nanofibers. Noting the convenience and flexibility in design, nanofibers merit a high surface-area-to-volume ratio, controlled release of therapeutics, mimicking of the extracellular matrix, and excellent mechanical properties. Core-shell nanofibers bring even further prospects to the realm of wound dressings upon separate compartments with independent functionality, adapted release profiles of bioactive agents, and better moisture management. In this review, we highlight core-shell nanofibers for wound dressing applications featuring a survey on common materials and synthesis methods. Our discussion embodies the wound healing process, optimal wound dressing characteristics, the current organic and inorganic material repertoire for multifunctional core-shell nanofibers, and common techniques to fabricate proper coaxial structures. We also provide an overview of antibacterial nanomaterials with an emphasis on their crystalline structures, properties, and functions. We conclude with an outlook for the potential offered by core-shell nanofibers toward a more advanced design for effective wound healing.

Reverse Gradient Distributions of Drug and Polymer Molecules within Electrospun Core-Shell Nanofibers for Sustained Release.

Core-shell nanostructures are powerful platforms for the development of novel nanoscale drug delivery systems with sustained drug release profiles. Coaxial electrospinning is facile and convenient for creating medicated core-shell nanostructures with elaborate designs with which the sustained-release behaviors of drug molecules can be intentionally adjusted. With resveratrol (RES) as a model for a poorly water-soluble drug and cellulose acetate (CA) and PVP as polymeric carriers, a brand-new electrospun core-shell nanostructure was fabricated in this study. The guest RES and the host CA molecules were designed to have a reverse gradient distribution within the core-shell nanostructures. Scanning electron microscope and transmission electron microscope evaluations verified that these nanofibers had linear morphologies, without beads or spindles, and an obvious core-shell double-chamber structure. The X-ray diffraction patterns and Fourier transform infrared spectroscopic results indicated that the involved components were highly compatible and presented in an amorphous molecular distribution state. In vitro dissolution tests verified that the new core-shell structures were able to prevent the initial burst release, extend the continuous-release time period, and reduce the negative tailing-off release effect, thus ensuring a better sustained-release profile than the traditional blended drug-loaded nanofibers. The mechanism underlying the influence of the new core-shell structure with an RES/CA reverse gradient distribution on the behaviors of RES release is proposed. Based on this proof-of-concept demonstration, a series of advanced functional nanomaterials can be similarly developed based on the gradient distributions of functional molecules within electrospun multi-chamber nanostructures.

Synergistic effect of electrophysiological microenvironment and bioactive ions for enhancing bone regeneration

Bone traumatic defects, requiring a long-term healing procedure cause the destruction of physical microenvironment, remain a critical challenge in orthopedic care. Given the electrical properties and bioactive elemental composition of natural bone, electrophysical microenvironment and bioactive ions play crucial roles in regulating bone metabolism. Our study constructs an implantable electret scaffold based on coaxial electrospinning technology. The core-shell electrospun fibrous membrane (PSPC) comprising shell structure of polycaprolactone (PCL)/calcium silicate nanowires (CSNs) loading with a core of polycaprolactone/silicon dioxide (SiO2) electret. In which, the sheath of the core-shell fibers is designed to continuously release bioactive ions to stimulate osteogenesis after the fiber degrades, while the core layer is intended to provide consistent endogenous electrical stimulation for osteogenic differentiation. This battery-free and biocompatible scaffold utilizes the synergistic outcome of electrical stimulation and bioactive ions and shows the most satisfactory osteogenic efficiency both in vitro and in vivo. Moreover, the underlying mechanism was interpreted that electrical stimulation-driven osteogenesis was driven by the activation of Calmodulin (CaM) / Calcineurin (CaN)/nuclear factor of activated T cells (NFAT) signaling pathway. This work proposes a potential strategy to improve bone regeneration by developing a coaxial electrospun fibrous membrane that combines the synergistic benefits of electrophysical microenvironment restoration and bioactive ions.

Thermal energy storage performance of liquid polyethylene glycol in core–shell polycarbonate and reduced graphene oxide fibers

Thermal energy storage is a promising, sustainable solution for challenging energy management issues. We deploy the fabrication of the reduced graphene oxide (rGO)–polycarbonate (PC) as shell and polyethylene glycol (PEG) as core to obtain hydrophobic phase change electrospun core–shell fiber system for low-temperature thermal management application. The encapsulation ratio of PEG is controlled by controlling the core flow rate, and ~ 93% heat energy storage efficacy is apparent for 1.5 mlh−1 of core flow rate. Moreover, the prepared fiber possesses maximum latent melting and freezing enthalpy of 30.1 ± 3.7 and 25.6 ± 4.0 Jg−1, respectively. The transient dynamic temperature vs. time curve of the rGO-loaded phase change fiber demonstrates the delay of fiber surface temperature change compared to pristine fiber. We indeed show that the tunable heat transfer and thermal energy storage efficacy of phase change fiber is achieved via controlled liquid PEG delivery and the addition of rGO in shell architecture. Notably, the effectiveness of unique phase change material (PCM)–based core–shell fibers is concluded from advanced scanning thermal microscopy (SThM) and self-thermoregulation tests.

Multi-hierarchical assemble nano-fibrous dressing for burn wound ultra-fast healing with dynamical exudate regulation, thermal management, and non-leaching sterilisation

To endow the nano-fibrous wound dressing with moisture-absorption, moisture-retention, thermal-management and anti-bacterial performances, a multi-hierarchical assemble process including electro-micro-encapsulation, electro-interpenetration and electro-deposition was used to create a structural integration including core–shell structure, interpenetrated structure and in-situ coating. First, a phase-transition thermal-management electro-spun consisting of PVDF shell and n-hexadecane core was fabricated from the coaxial electro-spinning, the heat-absorbing effect from n-hexadecane melting offers a cool feeling to make burn wounds feel comfortable. Second, an interpenetration process between PVA electro-spun and PVDF@n-hexadecane core–shell electro-spun was carried out by a heterologous co-electro-spinning device. By regulating the area density and the continuity of the hydrophilic phase and hydrophobic phase as well, the moisture-absorption and the moisture-retention performances can be manipulated. Third, a nano-capsule consisting of PCL outer shell and dual-component anti-bacterial agents as core was obtained from coaxial electrospray and then was further electro-deposited on the surface of the obtained interpenetrated membrane. After the melting of the PCL outer shell, not only the in-situ immobilization of anti-bacterial particles on the membrane surface (non-leaching sterilisation) was carried out, but also the exposure of anti-bacterial components. Owing to the collaborative integration of multiple functional ingredients and various structural elements, this composite nano-fibrous dressing displays a good moisture-absorption performance for removing exudate, a desired moisture-retention performance for offering wet surrounding to promote tissue regeneration, a comfortable absorption-heat effect and an excellent anti-bacterial performance. Combined with cytotoxicity and animal experiment evaluations, this multi-functional dressing presents a quicker healing period for second-degree burn compared to existed commercial fibrous dressing.

Heat-treated alginate-polycaprolactone core-shell nanofibers by emulsion electrospinning process for biomedical applications

Fabrication of Core-shell nanofibrous mat which is a promising tool for a wide range of applications in tissue engineering can be developed using water in oil (W/O) or oil in water (O/W) emulsion electrospinning. In this study, for the first time, we fabricated an O/W emulsion-based electrospun core-shell mat using polycaprolactone (PCL) as a core and the blend solution of alginate (Alg) and polyethylene oxide (PEO) as shell material. To achieve a stable core-shell mat, firstly, Alg was modified with heat treatment to decrease the molecular weight of Alg. Then, to improve the chain flexibility of Alg, PEO as a second polymer was added to facilitate its electrospinnability. The different volume ratios of O/W were then fabricated by adding PCL to the Alg-PEO solution to find an optimized emulsion solution. The morphology, swelling, and porosity of the construct were evaluated. At the same time, the mechanical characteristic of fibers was evaluated in both dry and wet conditions. This study also examined cell-scaffold interactions to address the need for a scaffolding material to be suitable for tissue engineering and biomedical applications. Finally, the result exhibited a distinct core-shell structure with better mechanical properties compared to the Alg-PEO.

Electrospinning of emulsions stabilized by octenylsuccinylated starch and pullulan

Emulsion electrospinning emerges as a promising technique for producing core-shell nanofibers used in delivering bioactive compounds. This work aims to investigate the feasibility of employing octenylsuccinylated (OS) starch-based emulsions in electrospinning for the fabrication of these nanofibers. The influence of sunflower seed oil concentration, ranging from 5% to 50%, on the emulsions was systematically examined. Increasing the oil concentration affects several key characteristics of the emulsions. These changes include a rise in apparent viscosity (from 0.78 to 7.72 Pa·s at 100 s−1) and average droplet size (from 1.21 to 1.79 μm), as well as a decrease in conductivity (from 727 to 193 μs/cm), leading to a larger average diameter of electrospun fibers, which increased from 294 to 533 nm. Confocal laser scanning microscopy and transmission electron microscopy confirmed the core–shell structure of the fibers. Furthermore, the correlation between fiber size and emulsion properties was discussed, and it was noted that the average fiber diameter, loading capacity, and encapsulation efficiency were significantly affected by emulsion composition and properties. These insights contribute to our understanding of the emulsion electrospinning process and offer a valuable guidance for the development of OS starch-based core–shell electrospun fibers.

Delivery of TGFβ3 from Magnetically Responsive Coaxial Fibers Reduces Spinal Cord Astrocyte Reactivity In Vitro.

A spinal cord injury (SCI) compresses the spinal cord, killing neurons and glia at the injury site and resulting in prolonged inflammation and scarring that prevents regeneration. Astrocytes, the main glia in the spinal cord, become reactive following SCI and contribute to adverse outcomes. The anti-inflammatory cytokine transforming growth factor beta 3 (TGFβ3) has been shown to mitigate astrocyte reactivity; however, the effects of prolonged TGFβ3 exposure on reactive astrocyte phenotype have not yet been explored. This study investigates whether magnetic core-shell electrospun fibers can be used to alter the release rate of TGFβ3 using externally applied magnetic fields, with the eventual application of tailored drug delivery based on SCI severity. Magnetic core-shell fibers are fabricated by incorporating superparamagnetic iron oxide nanoparticles (SPIONs) into the shell and TGFβ3 into the core solution for coaxial electrospinning. Magnetic field stimulation increased the release rate of TGFβ3 from the fibers by 25% over 7 days and released TGFβ3 reduced gene expression of key astrocyte reactivity markers by at least twofold. This is the first study to magnetically deliver bioactive proteins from magnetic fibers and to assess the effect of sustained release of TGFβ3 on reactive astrocyte phenotype.

Fabrication, characterization, and optimization of core–shell electrospun nanofibers for simultaneous sustained delivery of metformin and glibenclamide in type II diabetes treatment

Fabrication, characterization, and optimization of core–shell electrospun nanofibers for simultaneous sustained delivery of metformin and glibenclamide in type II diabetes treatment

Electrospun Core–Shell Carbon Nanofibers as Free-Standing Anode Materials for Sodium-Ion Batteries

Electrospun Core–Shell Carbon Nanofibers as Free-Standing Anode Materials for Sodium-Ion Batteries

Levofloxacin loaded poly (ethylene oxide)-chitosan/quercetin loaded poly (D,L-lactide-co-glycolide) core-shell electrospun nanofibers for burn wound healing.

This study developed a new burn wound dressing based on core-shell nanofibers that co-deliver antibiotic and antioxidant drugs. For this purpose, poly(ethylene oxide) (PEO)-chitosan (CS)/poly(D,L-lactide-co-glycolide) (PLGA) core-shell nanofibers were fabricated through co-axial electrospinning technique. Antibiotic levofloxacin (LEV) and antioxidant quercetin (QS) were incorporated into the core and shell parts of PEO-CS/PLGA nanofibers, respectively. The drugs could bond to the polymer chains through hydrogen bonding, leading to their steady release for 168h. An in vitro drug release study showed a burst effect followed by sustained release of LEV and QS from the nanofibers due to the Fickian diffusion. The NIH 3T3 fibroblast cell viability of the drug loaded core-shell nanofibers was comparable to that in the control (tissue culture polystyrene) implying biocompatibility of the nanofibers and their cell supportive role. However, there was no significant difference in cell viability between the drug loaded and drug free core-shell nanofibers. According to in vivo experiments, PEO-CS-LEV/PLGA-QS core-shell nanofibers could accelerate the healing process of a burn wound compared to a sterile gauze. Thanks to the synergistic therapeutic effect of LEV and QS, a significantly higher wound closure rate was recorded for the drug loaded core-shell nanofibrous dressing than the drug free nanofibers and control. Conclusively, PEO-CS-LEV/PLGA-QS core-shell nanofibers were shown to be a promising wound healing material that could drive the healing cascade through local co-delivery of LEV and QS to burn wounds.

Multifunctional embelin- poly (3-hydroxybutyric acid) and sodium alginate-based core-shell electrospun nanofibrous mat for wound healing applications

In this study, coaxial electrospinning is employed to make core-shell fibers, which represents a major advance in biomaterial innovation. Fibers that combine a protective shell and a therapeutic agent-loaded core, herald a revolutionary era in tissue engineering and wound care. Besides supporting cell growth, these fibers also preserve sterility, which makes them ideal for advanced wound dressings. We used embelin as the basis for this study because of its natural antibacterial properties. Its effectiveness in inhibiting the growth of bacteria made it the ideal candidate for our research. We have synthesized core-shell nanofibers that contain Sodium Alginate (SAL) in a Poly (ethylene oxide) (PEO) shell and Embelin in a Poly (3-hydroxybutyric acid) (PHB) core, which exhibit the homogeneity and flawless structure required for biomedical applications. When using SAL-PEO and EMB-PHB solutions dissolved in 1,1,1,3,3,3 hexafluoro-2-propanol (HFIP), high consistency in results can be achieved. A biocompatibility study was conducted using NIH-3T3 fibroblasts, which demonstrated remarkable adhesion and proliferation, with over 95 % growth supporting both PHB + SAL-PEO and EMB-PHB + SAL-PEO fibers. In addition, the scaffold loaded with Embelin shows strong antibacterial activity and cytocompatibility. The combined activity demonstrates the potential of EMB-PHB + SAL-PEO fibers in wound healing, where tissue regeneration and preservation of sterility are crucial. The optimized concentration of Embelin within these scaffolds demonstrates robust antibacterial efficacy while exhibiting minimal toxicity, thus positioning them as highly promising candidates for a wide range of biological applications, including wound healing.

Silver Nanoparticles In Situ Synthesized and Incorporated in Uniaxial and Core-Shell Electrospun Nanofibers to Inhibit Coronavirus.

In the present study, we sought to develop materials applicable to personal and collective protection equipment to mitigate SARS-CoV-2. For this purpose, AgNPs were synthesized and stabilized into electrospinning nanofiber matrices (NMs) consisting of poly(vinyl alcohol) (PVA), chitosan (CHT), and poly-ε-caprolactone (PCL). Uniaxial nanofibers of PVA and PVA/CHT were developed, as well as coaxial nanofibers of PCL[PVA/CHT], in which the PCL works as a shell and the blend as a core. A crucial aspect of the present study is the in situ synthesis of AgNPs using PVA as a reducing and stabilizing agent. This process presents few steps, no additional toxic reducing agents, and avoids the postloading of drugs or the posttreatment of NM use. In general, the in situ synthesized AgNPs had an average size of 11.6 nm, and the incorporated nanofibers had a diameter in the range of 300 nm, with high uniformity and low polydispersity. The NM's spectroscopic, thermal, and mechanical properties were appropriate for the intended application. Uniaxial (PVA/AgNPs and PVA/CHT/AgNPs) and coaxial (PCL[PVA/CHT/AgNPs]) NMs presented virucidal activity (log's reduction ≥ 5) against mouse hepatitis virus (MHV-3) genus Betacoronavirus strains. In addition to that, the NMs did not present cytotoxicity against fibroblast cells (L929 ATCC® CCL-1TM lineage).

Electrospun core-shell polycaprolactone/ chitosan nanofibrous composite with enhanced curcumin loading capacity for wound healing applications

Skin treatment complexity and expense in accidents such as burns, lacerations, and illnesses represent a significant concern. The demand for nanofibers possessing a high biocompatible matrix and the ability to carry drugs to improve wound healing is highly regarded. In this investigation, electrospun nanofibers were fabricated utilizing a 17 % (w/v) polycaprolactone (PCL) core and a 2 % (w/v) chitosan (CS) shell, encompassing varying concentrations of curcumin (CUR, 10 μM, 25 μM, and 50 μM), and their structural, physicochemical, mechanical, and in vitro characteristics of the prepared samples were thoroughly examined. A TEM image indicated the mean thickness of the core and shell in the drug-loaded sample to be approximately 60 nm and 170 nm, respectively. Smooth nanofibers with a bead-free shape structure were also discernible through SEM evaluation, with a porosity of 84.27 ± 5.32 % for the PCL/CS/CUR25μM sample. Moreover, the addition of CUR exhibited tensile properties within the range of the skin's mechanical characteristics, along with suitable wettability (40.80 ± 2.99°), water absorption (858.82 ± 79.06 %), and degradation rate (25.76 ± 4.90 %). The drug release profile of CUR exhibited a consistent release rate of 57.0 ± 3.9 % during the initial phase over a 24-h period. The seeded L929 cells' behavior on the scaffolds was assessed using the MTT assay and FESEM microimages. The PCL/CS/CUR25μM showed no cytotoxic effect on the seeded cells, and they exhibited appropriate adherence to the scaffolds. Therefore, the electrospun core-shell PCL/CS/CUR25μM nanofibrous composite has the potential to function as an appropriate membrane for wound healing applications.

Localized cancer photodynamic therapy approach based on core–shell electrospun nanofibers

Core–shell nanofibers loaded with porphyrin were produced to act as localized DDS for treating cervical cancer using PDT. Porphyrin-loaded electrospun nanofibers showed a higher phototoxic effect against tumor cells compared to non-tumor ones.