Electrospinning of type I collagen and PCL nanofibers using acetic acid

Innovative Approach to Accelerate Wound Healing: Synthesis and Validation of Enzymatically Cross-Linked COL-rGO Biocomposite Hydrogels

In this study, an innovative conductive hybrid biomaterial was synthetized using collagen (COL) and reduced graphene oxide (rGO) in order for it to be used as a wound dressing. The hydrogels were plasticized with glycerol and enzymatically cross-linked with horseradish peroxidase (HRP). A successful interaction among the components was demonstrated by FTIR, XRD, and XPS. It was demonstrated that increasing the rGO concentration led to higher conductivity and negative charge density values. Moreover, rGO also improved the stability of hydrogels, which was expressed by a reduction in the biodegradation rate. Furthermore, the hydrogel's stability against the enzymatic action of collagenase type I was also strengthened by both the enzymatic cross-linking and the polymerization of dopamine. However, their absorption capacity, reaching values of 215 g/g, indicates the high potential of the hydrogels to absorb fluids. The rise of these properties positively influenced the wound closure process, achieving an 84.5% in vitro closure rate after 48 h. These findings clearly demonstrate that these original composite biomaterials can be a viable choice for wound healing purposes.

Dual Functional Antibacterial-Antioxidant Core/Shell Alginate/Poly(ε-caprolactone) Nanofiber Membrane: A Potential Wound Dressing

Core/shell nanofibers offer the advantage of encapsulating multiple drugs with different hydrophilicity in the core and shell, thus allowing for the controlled release of pharmaceutic agents. Specifically, the burst release of hydrophilic drugs from such fiber membranes causes an instantaneous high drug concentration, whereas a long and steady release is usually desired. Herein, we tackle the problem of the initial burst release by the generation of core/shell nanofibers with the hydrophilic antibiotic drug gentamycin loaded within a hydrophilic alginate core surrounded by a hydrophobic shell of poly(ε-caprolactone). Emulsion electrospinning was used as the nanofibrous mesh generation procedure. This process also allows for the loading of a hydrophobic compound, where we selected a natural antioxidant molecule, betulin (BTL), to detoxify the radicals. The resulting nanofibers exhibited a cylindrical shape with a core/shell structure. In vitro tests showed a controlled release of gentamicin from nanofibers via diffusion. The drug reached 93% release in an alginate hydrogel film but only 50% release in the nanofibers, suggesting its potential to minimize the initial burst release. Antibacterial tests revealed significant activity against both Gram-negative and Gram-positive bacteria. The antioxidant property of betulin was confirmed through the DPPH assay, where the incorporation of 20% BTL revealed 37.3% DPPH scavenging. The nanofibers also exhibited favorable biocompatibility in cell culture studies, and no harmful effects on cell viability were observed. Overall, this research offers a promising approach to producing core/shell nanofibrous mats with antibacterial and antioxidant properties, which could effectively address the requirements of wound dressings, including infection prevention and wound healing acceleration.

Design and development of dual drug-loaded nanofibrous inserts for ophthalmic sustained delivery of AMK and VAN: Pharmacokinetic study in rabbit's eye

Bacterial corneal keratitis is a damage to the corneal tissue that if not treated, can cause various complications like severe vision loss or even blindness. Combination therapy with two antibiotics which are effective against Gram-positive and Gram-negative bacteria offers sufficient broad-spectrum antibiotic coverage for the treatment of keratitis. Nanofibers can be a potential carrier in dual drug delivery due to their structural characteristics, specific surface area and high porosity. In order to achieve a sustained delivery of amikacin (AMK) and vancomycin (VAN), the current study designed, assessed, and compared nanofibrous inserts utilizing polyvinyl alcohol (PVA) and polycaprolactone (PCL) as biocompatible polymers. Electrospinning method was utilized to prepare two different formulations, PVA-VAN/AMK and PCL/PVA-VAN/AMK, with 351.8 ± 53.59 nm and 383.85 ± 49 nm diameters, respectively. The nanofibers were simply inserted in the cul-de-sac as a noninvasive approach for in vivo studies. The data obtained from the physicochemical and mechanical properties studies confirmed the suitability of the formulations. Antimicrobial investigations showed the antibacterial properties of synthesized nanofibers against Staphylococcus aureus and Pseudomonas aeruginosa. Both in vitro and animal studies demonstrated sustained drug release of the prepared nanofibers for 120 h. Based on the in vivo findings, the prepared nanofibers' AUC0-120 was found to be 20 to 31 times greater than the VAN and AMK solutions. Considering the results, the nanofibrous inserts can be utilized as an effective and safe system in drug delivery.

Engineering of electrospun polycaprolactone/polyvinyl alcohol-collagen based 3D nano scaffolds and their drug release kinetics using cetirizine as a model drug

Combining the versatility of electrospinning with the biocompatibility of Polycaprolactone and Collagen, this study aims to create advanced 3D nano scaffolds for effective drug delivery. Ceramic materials like hydroxyapatite (nHAp) are incorporated as bioactive agents in the fibers. Electrospun PCL (Polycaprolactone)/collagen nanofibers and PVA (Poly-vinyl alcohol)/collagen are promising tissue-engineering substitutes with high biocompatibility, low cytotoxicity, and great tensile strength. Small pores in these nanofibers play a major role in drug delivery system. Owing to its short half-life, limited solubility, restricted bioavailability as well as re-crystallization concerns, the application of Cetirizine (CIT) has found little relevance. Electrospun nanofibers impregnated with CIT provide an excellent solution to combat these limitations, yield sustained drug release along with hampering drug re-crystallization. CIT-loaded polyvinyl alcohol (PVA)/collagen (Col) and CIT-loaded PVA/Col/nHAp nanofibers were characterized and further CIT anti-crystallization as well as release behaviors were investigated. FESEM and HRTEM were used to observe the morphology of the as-synthesized nanofibers. FTIR spectroscopy, water contact angle measurement and drug release studies verified the differences in performance of CIT-loaded PVA/Col and PVA/Col/nHAp nanofibers. The release trend of CIT through these as-synthesized nanoscaffolds was analyzed by various kinetic models and exhibited sustained release of CIT for up to 96 h.

Cold atmospheric plasma modified polycaprolactone solution prior to electrospinning: A novel approach for improving quercetin-loaded nanofiber drug delivery systems

In this study, we present a novel approach for enhancing the performance of Quercetin-loaded nanofiber drug delivery systems through the modification of Polycaprolactone (PCL) solution using Cold Atmospheric Plasma (CAP) prior to electrospinning. CAP treatment was applied to PCL solutions for varying durations, namely, 0.5, 1, and 3 min. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) collectively demonstrate that CAP application and QU loading induce morphological changes in nanofibers, facilitating the creation of drug delivery systems with modified fiber diameters, devoid of bead formation. CAP treatment duration correlates with varying fiber diameters, with the longest treatment (3 min) producing the largest fibers (1324 ± 387 nm). Concurrently, the incorporation of quercetin (QU) into the PCL nanofibers resulted in reduced fiber diameter. These observations emphasize the pivotal role of CAP modification in tailoring nanofiber size and morphology. Notably, minimal peak shifts indicate no significant molecular structure changes in PCL nanofibers compared to PCL solutions, assuring the absence of unwanted chemical modifications or degradation during electrospinning. Furthermore, specific QU peaks are undetectable in Fourier-transform infrared (FTIR) spectra, suggesting dispersed or amorphous QU molecules within the nanofibers. Additionally, X-ray diffraction (XRD) results demonstrate that CAP treatment does not alter the crystalline structure of the PCL nanofiber drug delivery system. Crystalline planes of PCL remain unchanged, affirming stability under CAP treatment conditions. Water contact angles indicate that CAP treatment affects nanofiber hydrophobicity, with shorter CAP treatment times rendering more hydrophilic surfaces. Cumulative QU release percentages vary, with PCL/CAP-0.5-QU exhibiting the highest release at 56 ± 2.2 %, surpassing unmodified PCL/QU. Moreover, cell viability remains comparable or slightly increased when QU is incorporated into CAP-treated PCL nanofibers, suggesting potential mitigation of cytotoxic effects induced by CAP treatment. The combination of QU and CAP treatment enhances cancer cell viability reduction, QU release from nanofibers, and drug loading efficiency in a synergistic manner.

Multi-needle blow-spinning technique for fabricating collagen nanofibrous nerve guidance conduit with scalable productivity and high performance

Nerve guidance conduits (NGCs) have been widely accepted as a promising strategy for peripheral nerve regeneration. Fabricating ideal NGCs with good biocompatibility, biodegradability, permeability, appropriate mechanical properties (space maintenance, suturing performance, etc.), and oriented topographic cues is still current research focus. From the perspective of translation, the technique stability and scalability are also an important consideration for industrial production. Recently, blow-spinning technique shows great potentials in nanofibrous scaffolds fabrication, possessing high quality, high fiber production rates, low cost, ease of maintenance, and high reliability. In this study, we proposed for the first time the preparation of a novel NGC via blow-spinning technique to obtain optimized performances and high productivity. A new collagen nanofibrous neuro-tube with the bilayered design was developed, incorporating inner oriented and outer random topographical cues. The bilayer structure enhances the mechanical properties of the conduit in dry and wet, displaying good radial support and suturing performance. The porous nature of the blow-spun collagen membrane enables good nutrient delivery and metabolism. The in vitro and in vivo evaluations indicated the bilayer-structure conduit could promoted Schwann cells growth, neurotrophic factors secretion, and axonal regeneration and motor functional recovery in rat.

Development of a PVA/PCL/CS-Based Nanofibrous Membrane for Guided Tissue Regeneration and Controlled Delivery of Doxycycline Hydrochloride in Management of Periodontitis: In Vivo Evaluation in Rats

Antibiotic administration is an adjacent therapy to guided tissue regeneration (GTR) in the management of periodontitis. This is due to the major role of pathogen biofilm in aggravating periodontal defects. This study aimed to fabricate a GTR membrane for sustained delivery of doxycycline hydrochloride (DOX) while having a space-maintaining function. The membranes were prepared using a polymeric blend of polycaprolactone/polyvinyl alcohol/chitosan by the electrospinning technique. The obtained membranes were characterized in terms of physicochemical and biological properties. Nanofibers showed a mean diameter in the submicron range of < 450 nm while having uniform randomly aligned morphology. The obtained membranes showed high strength and flexibility. A prolonged in vitro release profile during 68 h was observed for manufactured formulations. The prepared membranes showed a cell viability of > 70% at different DOX concentrations. The formulations possessed antimicrobial efficacy against common pathogens responsible for periodontitis. In vivo evaluation also showed prolonged release of DOX for 14 days. The histopathological evaluation confirmed the biocompatibility of the GTR membrane. In conclusion, the developed nanofibrous DOX-loaded GTR membranes may have beneficial characteristics in favour of both sustained antibiotic delivery and periodontal regeneration by space-maintaining function without causing any irritation and tissue damage.

Salivary Gland Bioengineering

Salivary gland dysfunction affects millions globally, and tissue engineering may provide a promising therapeutic avenue. This review delves into the current state of salivary gland tissue engineering research, starting with a study of normal salivary gland development and function. It discusses the impact of fibrosis and cellular senescence on salivary gland pathologies. A diverse range of cells suitable for tissue engineering including cell lines, primary salivary gland cells, and stem cells are examined. Moreover, the paper explores various supportive biomaterials and scaffold fabrication methodologies that enhance salivary gland cell survival, differentiation, and engraftment. Innovative engineering strategies for the improvement of vascularization, innervation, and engraftment of engineered salivary gland tissue, including bioprinting, microfluidic hydrogels, mesh electronics, and nanoparticles, are also evaluated. This review underscores the promising potential of this research field for the treatment of salivary gland dysfunction and suggests directions for future exploration.

Fabrication and multiscale modeling of polycaprolactone/amniotic membrane electrospun nanofiber scaffolds for wound healing

BACKGROUND

Enhancing the efficiency of cell-based skin tissue engineering (TE) approaches is possible via designing electrospun scaffolds possessing natural materials like amniotic membrane (AM) with wound healing characteristics. Concentrating on this aim, we fabricated innovative polycaprolactone (PCL)/AM scaffolds through the electrospinning process.

METHODS

The manufactured structures were characterized by employing scanning electron microscope (SEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, tensile testing, Bradford protein assay, etc. In addition, the mechanical properties of scaffolds were simulated by the multiscale modeling method.

RESULTS

As a result of conducting various tests, it was concluded that the uniformity and distribution of fibers decreased with an increase in the amniotic content. Furthermore, PCL-AM scaffolds contained amniotic and PCL characteristic bands. In the case of protein release, greater content of AM led to the release of higher amounts of collagen. Tensile testing revealed that scaffolds' ultimate strength increased when the AM content augmented. The multiscale modeling demonstrated that the scaffold had elastoplastic behavior. In order to assess cellular attachment, viability, and differentiation, human adipose-derived stem cells (ASCs) were seeded on the scaffolds. In this regard, SEM and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays showed significant cellular proliferation and viability on the proposed scaffolds, and these analyses illustrated that higher cell survival and adhesion could be achieved when scaffolds possessed a larger amount of AM. After 21 days of cultivation, particular keratinocyte markers, such as keratin I and involucrin, were identified through utilizing immunofluorescence and real-time polymerase chain reaction (PCR) tests. The markers' expressions were higher in the PCL-AM scaffold with a ratio of 90:10 v v-1 compared with the PCL-epidermal growth factor (EGF) structure. Moreover, the presence of AM in the scaffolds resulted in the keratinogenic differentiation of ASCs even without employing EGF. Consequently, this state-of-the-art experiment suggests that the PCL-AM scaffold can be a promising candidate in skin bioengineering.

CONCLUSION

This study showed that mixing AM with PCL, a widely used polymer, in different concentrations can overcome PCL disadvantages such as high hydrophobicity and low cellular compatibility.

Sustainable Collagen Blends with Different Ionic Liquids for Resistive Touch Sensing Applications

Considering the sustainable development goals to reduce environmental impact, sustainable sensors based on natural polymers are a priority as the large im plementation of these materials is required considering the Internet of Things (IoT) paradigm. In this context, the present work reports on sustainable blends based on collagen and different ionic liquids (ILs), including ([Ch][DHP], [Ch][TSI], [Ch][Seri]) and ([Emim][TFSI]), processed with varying contents and types of ILs in order to tailor the electrical response. Varying IL types and contents leads to different interactions with the collagen polymer matrix and, therefore, to varying mechanical, thermal, and electrical properties. Collagen/[Ch][Seri] samples display the most pronounced decrease of the tensile strength (3.2 ± 0.4 MPa) and an increase of the elongation at break (50.6 ± 1.5%). The best ionic conductivity value of 0.023 mS cm^-1 has been obtained for the sample with 40 wt % of the IL [Ch][Seri]. The functional response of the collagen-IL films has been demonstrated on a resistive touch sensor whose response depends on the ionic conductivity, being suitable for the next generation of sustainable touch sensing devices.

Micro-Injection Moulding of PEO/PCL Blend–Based Matrices for Extended Oral Delivery of Fenbendazole

Fenbendazole (FBZ) is a broad-spectrum anthelmintic administered orally to ruminants; nevertheless, its poor water solubility has been the main limitation to reaching satisfactory and sustained levels at the site of the target parasites. Hence, the exploitation of hot-melt extrusion (HME) and micro-injection moulding (µIM) for the manufacturing of extended-release tablets of plasticised solid dispersions of poly(ethylene oxide) (PEO)/polycaprolactone (PCL) and FBZ was investigated due to their unique suitability for semi-continuous manufacturing of pharmaceutical oral solid dosage forms. High-performance liquid chromatography (HPLC) analysis demonstrated a consistent and uniform drug content in the tablets. Thermal analysis using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) suggested the amorphous state of the active ingredient, which was endorsed by powder X-ray diffraction spectroscopy (pXRD). Fourier transform infrared spectroscopy (FTIR) analysis did not display any new peak indicative of either a chemical interaction or degradation. Scanning electron microscopy (SEM) images showed smoother surfaces and broader pores as we increased the PCL content. Electron-dispersive X-ray spectroscopy (EDX) revealed that the drug was homogeneously distributed within the polymeric matrices. Drug release studies attested that all moulded tablets of amorphous solid dispersions improved the drug solubility, with the PEO/PCL blend–based matrices showing drug release by Korsmeyer–Peppas kinetics. Thus, HME coupled with µIM proved to be a promising approach towards a continuous automated manufacturing process for the production of oral solid dispersions of benzimidazole anthelmintics to grazing cattle.

Investigation on Centrifugally Spun Fibrous PCL/3-Methyl Mannoside Mats for Wound Healing Application

Fibrous structures, in general, have splendid advantages in different forms of micro- and nanomembranes in various fields, including tissue engineering, filtration, clothing, energy storage, etc. In the present work, we develop a fibrous mat by blending the bioactive extract of Cassia auriculata (CA) with polycaprolactone (PCL) using the centrifugal spinning (c-spinning) technique for tissue-engineered implantable material and wound dressing applications. The fibrous mats were developed at a centrifugal speed of 3500 rpm. The PCL concentration for centrifugal spinning with CA extract was optimized at 15% w/v of PCL to achieve better fiber formation. Increasing the extract concentration by more than 2% resulted in crimping of fibers with irregular morphology. The development of fibrous mats using a dual solvent combination resulted in fine pores on the fiber structure. Scanning electron microscope (SEM) images showed that the surface morphology of the fibers in the produced fiber mats (PCL and PCL-CA) was highly porous. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that the CA extract contained 3-methyl mannoside as the predominant component. The in vitro cell line studies using NIH3T3 fibroblasts demonstrated that the CA-PCL nanofiber mat was highly biocompatible, supporting cell proliferation. Hence, we conclude that the c-spun, CA-incorporating nanofiber mat can be employed as a tissue-engineered construct for wound healing applications.

Enhanced sciatic nerve regeneration with fibrin scaffold containing human endometrial stem cells and insulin encapsulated chitosan particles: An in vivo study

BACKGROUND

Based on recent advances in tissue engineering and stem cell therapy in nervous system diseases treatments, this study aimed to investigate sciatic nerve regeneration using human endometrial stem cells (hEnSCs) encapsulated fibrin gel containing chitosan nanoparticle loaded by insulin (Ins-CPs). Stem cells and also Insulin (Ins), which is a strong signaling molecule in peripheral nerve regeneration, play an important role in neural tissue engineering.

METHODS

The fibrin hydrogel scaffold containing insulin loaded chitosan particles was synthesized and characterized. Release profiles of insulin from hydrogel was determined through UV-visible spectroscopy. Also, human endometrial stem cells encapsulated in hydrogel and its cell biocompatibility were assigned. Furthermore, the sciatic nerve crush injury was carried out and prepared fibrin gel was injected at the crush injury site by an 18-gage needle. Eight and twelve weeks later, the recovery of motor and sensory function and histopathological evaluation were assessed.

RESULTS

The in vitro experiments showed that the insulin can promote hEnSCs proliferation within a certain concentration range. Animals' treatment confirmed that developed fibrin gel containing Ins-CPs and hEnSCs significantly improves motor function and sensory recovery. Hematoxylin and Eosin (H&E) images provided from cross-sectional and, longitudinal-sections of the harvested regenerative nerve showed that regenerative nerve fibers had been formed and accompanied with new blood vessels in the fibrin/insulin/hEnSCs group.

CONCLUSION

Our results demonstrated that the prepared hydrogel scaffolds containing insulin nanoparticles and hEnSCs could be considered as a potential biomaterial aimed at regeneration of sciatic nerves.

Effect of Electrospun PLGA/Collagen Scaffolds on Cell Adhesion, Viability, and Collagen Release: Potential Applications in Tissue Engineering

The development of scaffolding obtained by electrospinning is widely used in tissue engineering due to porous and fibrous structures that can mimic the extracellular matrix. In this study, poly (lactic-co-glycolic acid) (PLGA)/collagen fibers were fabricated by electrospinning method and then evaluated in the cell adhesion and viability of human cervical carcinoma HeLa and NIH-3T3 fibroblast for potential application in tissue regeneration. Additionally, collagen release was assessed in NIH-3T3 fibroblasts. The fibrillar morphology of PLGA/collagen fibers was verified by scanning electron microscopy. The fiber diameter decreased in the fibers (PLGA/collagen) up to 0.6 µm. FT-IR spectroscopy and thermal analysis confirmed that both the electrospinning process and the blend with PLGA give structural stability to collagen. Incorporating collagen in the PLGA matrix promotes an increase in the material's rigidity, showing an increase in the elastic modulus (38%) and tensile strength (70%) compared to pure PLGA. PLGA and PLGA/collagen fibers were found to provide a suitable environment for the adhesion and growth of HeLa and NIH-3T3 cell lines as well as stimulate collagen release. We conclude that these scaffolds could be very effective as biocompatible materials for extracellular matrix regeneration, suggesting their potential applications in tissue bioengineering.

Novel polycaprolactone (PCL)-type I collagen core-shell electrospun nanofibers for wound healing applications

Type I collagen (Col_1) is one of the main proteins present in the skin extracellular matrix, serving as support for skin regeneration and maturation in its granulation stage. Electrospun materials have been intensively studied as the next generation of skin wound dressing mainly due to their high surface area and fibrous porosity. However, the electrospinning of collagen-based solutions causes degradation of its structure. In this work, a coaxial electrospinning process was proposed to overcome this limitation. The production of mats of polycaprolactone (PCL)-Col_1/PVA (collagen/poly(vinyl alcohol)) composed of core-shell nanofibers was investigated. PCL solution was used as the core solution, while Col_1/PVA was used as the shell solution. PVA was used to improve the processability of collagen, while PCL was employed to improve the mechanical properties and morphology of Col_1/PVA fibers. The morphology and the cytotoxicity of the fibers were highly dependent on the processing parameters. Defect-free core-shell nanofibers were obtained with a shell/core flow rates ratio = 4, flight distance of 12 cm, and an applied voltage of 16 kV. Using this strategy, the triple helix structure characteristic of the collagen molecule was preserved. Moreover, the common post-processing of solvent removal could be suppressed, simplifying the manufacturing processing of these biomaterials. The nanostructured mats showed no cytotoxicity, high liquid absorption, structural stability, hydrophilic character, and collagen release capacity, making them a potential novel dressing for skin damage regeneration, in special in the case of chronic wounds treatment, in which exogenous collagen delivery is necessary.

Kiwi extract-incorporated poly(ɛ-caprolactone)/cellulose acetate blend nanofibers for healing acceleration of burn wounds

Kiwi extract (KE) including different components such as quercetin, vitamins C and E, and actinides has been known as a debridement agent for burn wounds. In this study, electrospun poly(ɛ-caprolactone)/cellulose acetate blend nanofibers incorporating KE (PCL/CA/KE) were prepared and their performance was evaluated for healing acceleration of burn wounds. The physicochemical characterization of PCL/CA/KE nanofibers showed an average diameter of ∼420 nm, porosity of 70%, water contact angle of 61°, and water uptake of ∼220%. Moreover, the continuous release trend of KE from PCL/CA blend nanofibers happened during 24 h and the release mechanism was governed by the Fickian diffusion. Besides the cytocompatibility of PCL/CA/KE nanofibers, their in vivo experiments revealed that the bioactive wound dressing based on the sample has higher wound closure compared to KE after 21 days. Histopathology of wounds dressed by PCL/CA/KE nanofibers indicated epidermal formation along with a fully extended layer. Eventually, the obtained results confirmed that the PCL/CA/KE nanofibrous sample was a promising wound dressing for burn wound healing.

Compatibility Study between Fenbendazole and Polymeric Excipients Used in Pharmaceutical Dosage Forms Using Thermal and Non-Thermal Analytical Techniques

The body of work described in this research paper evaluates the compatibility between Fenbendazole (Fen), which is a broad-spectrum anthelmintic with promising antitumor activity, and three polymeric excipients commonly applied in pharmaceutical dosage forms. The assessment of binary mixtures was performed by differential scanning calorimetry and thermogravimetric analysis/derivative thermogravimetry to predict physical and/or chemical interactions, followed by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), and high-performance liquid chromatography (HPLC) to confirm or exclude any interactions. Thermal studies suggested the presence of interactions between Fen and P 407, PCL, and PLA. To validate these data, XRD showed that Fen is compatible with PCL and PLA, suggesting some interaction with P 407. FTIR demonstrated that PCL and PLA can establish physical interactions with Fen; moreover, it suggested that P 407 interacts not only physically but also chemically, which was later proved by HPLC to be only new intermolecular interactions. This work supports the further application of P 407, PCL, and PLA for the development of new medicinal and veterinary formulations containing Fen, since they do not affect the physical and chemical characteristics of the active ingredient and consequently its bioavailability and therapeutic efficacy.

Surface Modification of 3D-Printed PCL/BG Composite Scaffolds via Mussel-Inspired Polydopamine and Effective Antibacterial Coatings for Biomedical Applications

A wide variety of composite scaffolds with unique geometry, porosity and pore size can be fabricated with versatile 3D printing techniques. In this work, we fabricated 3D-printed composite scaffolds of polycaprolactone (PCL) incorporating bioactive glass (BG) particles (13-93 and 13-93B3 compositions) by using fused deposition modeling (FDM). The scaffolds were modified with a "mussel-inspired surface coating" to regulate biological properties. The chemical and surface properties of scaffolds were analyzed by Fourier transform infrared spectroscopy (FTIR), contact angle and scanning electron microscopy (SEM). Polydopamine (PDA) surface-modified composite scaffolds exhibited attractive properties. Firstly, after the surface modification, the adhesion of a composite coating based on gelatin incorporated with strontium-doped mesoporous bioactive glass (Sr-MBGNs/gelatin) was significantly improved. In addition, cell attachment and differentiation were promoted, and the antibacterial properties of the scaffolds were increased. Moreover, the bioactivity of these scaffolds was also significantly influenced: a hydroxyapatite layer formed on the scaffold surface after 3 days of immersion in SBF. Our results suggest that the promoting effect of PDA coating on PCL-BG scaffolds leads to improved scaffolds for bone tissue engineering.

Formulation and Evaluation of Fenbendazole Extended-Release Extrudes Processed by Hot-Melt Extrusion

This study aimed to demonstrate the feasibility of hot-melt extrusion in the development of extended-release formulations of Fenbendazole (Fen) dispersed in PEO/PCL blend-based matrices. Their thermal, physical, chemical and viscosity properties were assessed by differential scanning calorimetry, thermogravimetric analysis/derivative thermogravimetry, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and melt flow index. Drug dispersion was analyzed by scanning electron microscopy with electron dispersive X-ray spectroscopy, and drug release was evaluated by ultraviolet-visible spectroscopy. A thermal analysis indicated the conversion of the drug to its amorphous state. FTIR analysis endorsed the thermal studies pointing to a decrease in the drug's crystallinity with the establishment of intermolecular interactions. XRD analysis confirmed the amorphous nature of Fen. MFI test revealed that PCL acts as a plasticizer when melt-processed with PEO. SEM images displayed irregular surfaces with voids and pores, while EDX spectra demonstrated a homogeneous drug distribution throughout the polymeric carrier. Dissolution testing revealed that PCL retards the drug release proportionally to the content of such polymer incorporated. These melt-extruded matrices showed that the drug release rate in a PEO/PCL blend can easily be tailored by altering the ratio of PCL to address the issues related to the multiple-dosing regimen of Fen in ruminants.

Electrospun Polycaprolactone (PCL) Degradation: An In Vitro and In Vivo Study

Polycaprolactone (PCL) is widely used in tissue engineering due to its interesting properties, namely biocompatibility, biodegradability, elastic nature, availability, cost efficacy, and the approval of health authorities such as the American Food and Drug Administration (FDA). The PCL degradation rate is not the most adequate for specific applications such as skin regeneration due to the hydrophobic nature of bulk PCL. However, PCL electrospun fiber meshes, due to their low diameters resulting in high surface area, are expected to exhibit a fast degradation rate. In this work, in vitro and in vivo degradation studies were performed over 90 days to evaluate the potential of electrospun PCL as a wound dressing. Enzymatic and hydrolytic degradation studies in vitro, performed in a static medium, demonstrated the influence of lipase, which promoted a rate of degradation of 97% for PCL meshes. In an in vivo scenario, the degradation was slower, although the samples were not rejected, and were well-integrated in the surrounding tissues inside the subcutaneous pockets specifically created.

Pulsatile Controlled Release and Stability Evaluation of Polymeric Particles Containing Piper nigrum Essential Oil and Preservatives

Considerable efforts have been spent on environmentally friendly particles for the encapsulation of essential oils. Polymeric particles were developed to encapsulate the essential oil from Piper nigrum based on gelatin and poly-ε-caprolactone (PCL) carriers. Gas Chromatography ((Flame Ionization Detection (GC/FID) and Mass Spectrometry (GC/MS)), Atomic Force Microscopy (AFM), Nanoparticle Tracking Analysis (NTA), Confocal Laser Scanning Microscopy (CLSM), Attenuated Total Reflectance-Fourier-transform Infrared Spectroscopy (ATR-FTIR), and Ultraviolet-Visible (UV-VIS) spectroscopy were used for the full colloidal system characterization. The essential oil was mainly composed of β-caryophyllene (~35%). The stability of the encapsulated systems was evaluated by Encapsulation Efficiency (EE%), electrical conductivity, turbidity, pH, and organoleptic properties (color and odor) after adding different preservatives. The mixture of phenoxyethanol/isotialzoni-3-one (PNE system) resulted in enhanced stability of approximately 120 and 210 days under constant handling and shelf-life tests, respectively. The developed polymeric system presented a similar controlled release in acidic, neutral, or basic pH, and the release curves suggested a pulsatile release mechanism due to a complexation of essential oil in the PCL matrix. Our results showed that the developed system has potential as an alternative stable product and as a controlling agent, due to the pronounced bioactivity of the encapsulated essential oil.

Piperine-loaded electrospun nanofibers, an implantable anticancer controlled delivery system for postsurgical breast cancer treatment

Tumorectomy followed by radiotherapy, hormone, and chemotherapy, are the current mainstays for breast cancer treatment. However, these strategies have systemic toxicities and limited treatment outcomes. Hence, there is a crucial need for a novel controlled release delivery system for implantation following tumor resection to effectively prevent recurrence. Here, we fabricated polycaprolactone (PCL)-based electrospun nanofibers containing piperine (PIP), known for chemopreventive and anticancer activities, and also evaluated the impact of collagen (Coll) incorporation into the matrices. In addition to physicochemical characterization such as morphology, hydrophilicity, drug content, release properties, and mechanical behaviors, fabricated nanofibers were investigated in terms of cytotoxicity and involved mechanisms in MCF-7 and 4T1 breast tumor cell lines. In vivo antitumor study was performed in 4T1 tumor-bearing mice. PIP-PCL⁷⁵-Coll²⁵ nanofiber was chosen as the optimum formulation due to sustained PIP release, good mechanical performance, and superior cytotoxicity. Demonstrating no organ toxicity, animal studies confirmed the superiority of locally administered PIP-PCL⁷⁵-Coll²⁵ nanofiber in terms of inhibition of growth tumor, induction of apoptosis, and reduction of cell proliferation compared to PIP suspension, blank nanofiber, and the control. Taken together, we concluded that PIP-loaded nanofibers can be introduced as a promising treatment for implantation upon breast tumorectomy.

Emulsion electrospinning of sodium alginate/poly(ε-caprolactone) core/shell nanofibers for biomedical applications

Electrospun nanofibers have shown great potential as drug vehicles and tissue engineering scaffolds. However, the successful encapsulation of multiple hydrophilic/hydrophobic therapeutic compounds is still challenging. Herein, sodium alginate/poly(ε-caprolactone) core/shell nanofibers were fabricated via water-in-oil emulsion electrospinning. The sodium alginate concentration, water-to-oil ratio, and surfactant concentration were optimized for the maximum stability of the emulsion. The results demonstrated that an increasing water-to-oil ratio results in more deviation from Newtonian fluid and leads to a broader distribution of the fibers' diameters. Moreover, increasing poly(ε-caprolactone) concentration increases loss and storage moduli and increases the diameter of the resulting fibers. The nanofibers' characteristics were investigated by scanning electron microscopy, transmission electron microscopy, confocal laser scanning microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and water contact angle measurements. It was observed that using an emulsion composition of 10% (w/v) PCL and a water-to-oil ratio of 0.1 results in smooth, cylindrical, and uniform core/shell nanofibers with PCL in the shell and ALG in the core. The in vitro cell culture study demonstrated the favorable biocompatibility of nanofibers. Overall, this study provides a promising and trustworthy material for biomedical applications.

PCL/Col I-based magnetic nanocomposite scaffold provides an osteoinductive environment for ADSCs in osteogenic cues-free media conditions

Background

The bone tissue engineering (BTE) approach has been introduced as an alternative to conventional treatments for large non-healing bone defects. Magnetism promotes stem cells' adherence to biocompatible scaffolds toward osteoblast differentiation. Furthermore, osteogenic differentiation media are expensive and any changes in its composition affect stem cells differentiation. Moreover, media growth factors possess a short half-life resulting in the rapid loss of their functions in vivo. With the above in mind, we fabricated a multilayered nanocomposite scaffold containing the wild type of Type I collagen (Col I) with endogenous magnetic property to promote osteogenesis in rat ADSCs with the minimum requirement of osteogenic differentiation medium.

Methods

Fe₃O₄ NPs were synthesized by co-precipitation method and characterized using SEM, VSM, and FTIR. Then, a PCL/Col I nanocomposite scaffold entrapping Fe₃O₄ NPs was fabricated by electrospinning and characterized using SEM, TEM, AFM, VSM, Contact Angle, tensile stretching, and FTIR. ADSCs were isolated from rat adipose tissue and identified by flow cytometry. ADSCs were loaded onto PCL/Col I and PCL/Col I/Fe₃O₄-scaffolds for 1–3 weeks with/without osteogenic media conditions. The cell viability, cell adhesion, and osteogenic differentiation were evaluated using MTT assay, SEM, DAPI staining, ALP/ARS staining, RT-PCR, and western blotting, respectively.

Results

SEM, VSM, and FTIR results indicated that Fe₃O₄ was synthesized in nano-sized (15–30 nm) particles with spherical-shaped morphology and superparamagnetic properties with approved chemical structure as FTIR revealed. According to SEM images, the fabricated magnetic scaffolds consisted of nanofiber (500–700 nm). TEM images have shown the Fe₃O₄ NPs entrapped in the scaffold's fiber without bead formation. FTIR spectra analysis confirmed the maintenance of the natural structure of Col I, PCL, and Fe₃O₄ upon electrospinning. AFM data have shown that MNPs incorporation introduced stripe-like topography to nanofibers, while the depth of the grooves has decreased from 800 to 500 nm. Flow cytometry confirmed the phenotype of ADSCs according to their surface markers (i.e., CD29 and CD105). Additionally, Fe₃O₄ NP improved nanocomposite scaffold strength, wettability, porosity, biocompatibility and also facilitates the ALP activity, calcium-mineralization. Finally, magnetic nanocomposite scaffolds upregulated osteogenic-related genes or proteins’ expression (e.g., Col I, Runx2, OCN, ON, BMP2) in seeded ADSCs with/without osteo-differentiation media conditions.

Conclusions

Together, these results indicate that Fe₃O₄ NPs within the natural structure of Col I increase osteogenic differentiation in osteogenic cues-free media conditions. This effect could be translated in vivo toward bone defects healing. These findings support the use of natural ECM materials alongside magnetic particles as composite scaffolds to achieve their full therapeutic potential in BTE treatments.

Graphical Abstract

Polyethylene Oxide Assisted Fish Collagen-Poly-ε-Caprolactone Nanofiber Membranes by Electrospinning

Fish collagen has higher biocompatibility and lower immunogenicity than terrestrial collagen, and is currently one of the important raw materials for preparing biological materials. In this study, PEO was used as a spinning aid to prepare fish skin collagen-PCL nanofiber membranes by electrospinning, and the process was optimized to get smooth nanofibers. The morphological and mechanical properties of collagen-PCL nanofiber membranes were assessed by scanning electron microscopy (SEM). The changes in chemical composition due to the incorporation of collagen into PCL and PEO were determined by Fourier Transform infrared spectroscopy (FTIR). The biocompatibility of the collagen-PCL nanofiber membranes was evaluated in vitro in cultures of mouse fibroblasts and in vivo by subcutaneous implantation studies in rats. It was found that the diameter of the spun fibers became fine and smooth when the ratio of the collagen/PCL increased. The finally obtained nanofiber had good mechanical strength, porosity, and hydrophilicity, and could promote cell adhesion and proliferation. The FC-PCL nanofiber membrane prepared by this route opens a new way to prepare fish collagen biomaterials with electrospinning.

Expanding the Repertoire of Electrospinning: New and Emerging Biopolymers, Techniques, and Applications

Electrospinning has emerged as a versatile and accessible technology for fabricating polymer fibers, particularly for biological applications. Natural polymers or biopolymers (including synthetically derivatized natural polymers) represent a promising alternative to synthetic polymers, as materials for electrospinning. Many biopolymers are obtained from abundant renewable sources, are biodegradable, and possess inherent biological functions. This review surveys recent literature reporting new fibers produced from emerging biopolymers, highlighting recent developments in the use of sulfated polymers (including carrageenans and glycosaminoglycans), tannin derivatives (condensed and hydrolyzed tannins, tannic acid), modified collagen, and extracellular matrix extracts. The proposed advantages of these biopolymer-based fibers, focusing on their biomedical applications, are also discussed to highlight the use of new and emerging biopolymers (or new modifications to well-established ones) to enhance or achieve new properties for electrospun fiber materials.

Preparation of Electrospun Polyvinyl Alcohol/Nanocellulose Composite Film and Evaluation of Its Biomedical Performance

Using polyvinyl alcohol (PVA) and nanocellulose (NC) as raw materials, PVA/NC nanofiber membranes were prepared by electrospinning. The hydrogen bonding, crystalline properties and microscopic appearance of PVA/NC membranes with different NC contents were characterized. The mechanical properties, liquid absorption and cytotoxicity of the nanofiber membrane were evaluated. The results show that the free hydroxyl group of the PVA/NC nanofiber membranes have a maximum value of 9% at a mass fraction of 6% NC. The crystallinity of the PVA/NC nanofiber membranes and the average diameter of the nanofibers decreased and then increased as the NC content increased, with a minimum value of 38.23% and 272.03 nm, respectively, at 6% NC content. At this time, the contact angle was the smallest. The maximum strength of the PVA/NC nanofiber membranes is 75.8% higher than that of the PVA membrane at 2% NC content. With increasing NC content, the absorption of water, PBS sustained-release suspensions and artificial blood by PVA/NC nanofiber membranes increases. Cytotoxicity tests have shown that PVA/NC nanofiber membranes are non-toxic, have good cytocompatibility and are expected to be used in the field of medical dressings.

Electrospun Membranes as a Porous Barrier for Molecular Transport: Membrane Characterization and Release Assessment

Electrospun nanofibers have been extensively studied for encapsulated drugs releasing from the inside of the fiber matrix, but have been barely looked at for their potential to control release as a semi-permeable membrane. This study investigated molecular transport behaviors across nanofiber membranes with different micro-structure sizes and compositions. Four types of membranes were made by 5% and 10% poly (ε-caprolactone) (PCL) solutions electro-spun with or without 50 nm calcium carbonate (CaCO3) nanoparticles. The membranes were tested for thickness, fiber diameter, pore size, porosity, tensile strength and elongation, contact angle of water and their impacts on molecular transport behaviors. The presence of the CaCO3 nanoparticles made the 5% membranes stronger and stiffer but the 10% membranes weaker and less stiff due to the different (covering or embedded) locations of the nanoparticles with the corresponding fibers. Solute transport studies using caffeine as the model drug found the 5% membranes further retarded release from the 10% membranes, regardless of only half the amount of material being used for synthesis. The addition of CaCO3 nanoparticles aided the water permeation process and accelerated initial transports. The difference in release profiles between 5% and 10% membranes suggests different release mechanisms, with membrane-permeability dominated release for 5% PCL membranes and solute-concentration-gradient dominated release for 10% PCL membranes.

Facile modification of polycaprolactone nanofibers with egg white protein

Synthetic polymers remain to be a major choice for scaffold fabrication due to their structural stability and mechanical strength. However, the lack of functional moieties limits their application for cell-based therapies which necessitate modification and functionalization. Blending synthetic polymers with natural components is a simple and effective way to achieve the desired biological properties for a scaffold. Herein, nanofibrous mats made of polycaprolactone (PCL) and egg white protein (EWP) blend were developed and further evaluated for use as a scaffold for tissue engineering applications. Homogeneous distribution of EWP was achieved throughout the nanofibrous mats, as shown by immunohistochemistry. ATR-FTIR analysis and contact angle measurements have further confirmed the presence of EWP on the surface of the samples. The swelling test showed that PCL/EWP nanofibers have higher water uptake than PCL nanofibrous mats. Also, EWP addition on the nanofibrous mats resulted in an increase in the tensile strength and Young's modulus of the mats, indicating that the presence of protein can greatly enhance the mechanical properties of the mats. A significantly higher, more uniform, and dispersed cell spreading was observed on days 7 and 14 than that on neat PCL mats, demonstrating the importance of providing the required cues for cell homing by the availability of EWP. Hence, EWP is shown to be a simple and low-cost source for the functionalization of PCL nanofibrous mats. EWP is, therefore, a facile candidate to enhance cellular interactions of synthetic polymers for a wide range of tissue engineering applications.

Fabrication and in vitro evaluation of 3D composite scaffold based on collagen/hyaluronic acid sponge and electrospun polycaprolactone nanofibers for peripheral nerve regeneration

Replacement of peripheral nerve autografts with tissue engineered nerve grafts will potentially resolve the lack of nerve tissue especially in patients with severe concomitant soft tissue injuries. This study attempted to fabricate a tissue engineered nerve graft composed of electrospun PCL conduit filled with collagen-hyaluronic acid (COL-HA) sponge with different COL-HA weight ratios including 100:0, 98:2, 95:5 and 90:10. The effect of HA addition on the sponge porosity, mechanical properties, water absorption and degradation rate was assessed. A good cohesion between the electrospun PCL nanofibers and COL-HA sponges were seen in all sponges with different HA contents. Mechanical properties of PCL nanofibrous layer were similar to the rat sciatic nerve; the ultimate tensile strength was 2.23 ± 0.35 MPa at the elongation of 35%. Additionally, Schwann cell proliferation and morphology on three dimensional (3D) composite scaffold were evaluated by using MTT and SEM assays, respectively. Rising the HA content resulted in higher water absorption as well as greater pore size and porosity, while a decrease in Schwann cell proliferation compared to pure collagen sponge, although reduction in cell proliferation was not statistically significant. The lower Schwann cell proliferation on the COL-HA was attributed to the greater degradation rate and pore size of the COL-HA sponges. Also, dorsal root ganglion assay showed that the engineered 3D construct significantly increases axon growth. Taken together, these results suggest that the fabricated 3D composite scaffold provide a permissive environment for Schwann cells proliferation and maturation and can encourage axon growth.

Electrospun porous bilayer nano-fibrous fish collagen/PCL bio-composite scaffolds with covalently cross-linked chitooligosaccharides for full-thickness wound-healing applications

The development of tissue-engineered biodegradable artificial tissue substitutes with extracellular matrix-mimicking properties that govern the interaction between the material and biological environment is of great interest in wound-healing applications. In the present study, novel bilayer nanofibrous scaffolds composed of fish collagen (FC) and poly(ε-caprolactone) (PCL) were fabricated using electrospinning, with the covalent attachment of chitooligosaccharides (COS) via carbodiimide chemistry. The architecture and fiber diameter of the non-cross-linked nanofibrous scaffolds remained consistent irrespective of the polymer ratio under different electrospinning conditions, but the fiber diameter changed after cross-linking in association with the FC content. Fourier-transform infrared spectroscopy analysis indicated that the blend of biomaterials was homogenous, with an increase in COS levels with increasing FC content in the nanofibrous scaffolds. Based on cytocompatibility analysis (i.e., the cellular response to the nanofibrous scaffolds and their interaction), the nanofibrous scaffolds with high FC content were functionally active in response to normal human dermal fibroblast‑neonatal (NHDF-neo) and HaCaT keratinocyte cells, leading to the generation of a very effective tissue-engineered implant for full-thickness wound-healing applications. In addition to these empirical results, an assessment of the hydrophilicity, swelling, and mechanical integrity of the proposed COS-containing FC-rich FC/PCL (FCP) nanofibrous scaffolds confirmed that they have significant potential for use as tissue-engineered skin implants for rapid skin regeneration.

In-vitro Characterization of a Hernia Mesh Featuring a Nanostructured Coating

Abdominal hernia repair is a frequently performed surgical procedure worldwide. Currently, the use of polypropylene (PP) surgical meshes for the repair of abdominal hernias constitutes the primary surgical approach, being widely accepted as superior to primary suture repair. Surgical meshes act as a reinforcement for the weakened or damaged tissues and support tissue restoration. However, implanted meshes could suffer from poor integration with the surrounding tissues. In this context, the present study describes the preliminary evaluation of a PCL-Gel-based nanofibrous coating as an element to develop a multicomponent hernia mesh device (meshPCL-Gel) that could overcome this limitation thanks to the presence of a nanostructured biomimetic substrate for enhanced cell attachment and new tissue formation. Through the electrospinning technique, a commercial PP hernia mesh was coated with a nanofibrous membrane from a polycaprolactone (PCL) and gelatin (Gel) blend (PCL-Gel). Resulting PCL-Gel nanofibers were homogeneous and defect-free, with an average diameter of 0.15 ± 0.04 μm. The presence of Gel decreased PCL hydrophobicity, so that membranes average water contact angle dropped from 138.9 ± 1.1° (PCL) to 99.9 ± 21.6°, while it slightly influenced mechanical properties, which remained comparable to those of PCL (E = 15.7 ± 2.7 MPa, σ R = 7.7 ± 0.6 ε R = 118.8 ± 13.2%). Hydrolytic and enzymatic degradation was conducted on PCL-Gel up to 28 days, with maximum weight losses around 20 and 40%, respectively. The meshPCL-Gel device was obtained with few simple steps, with no influences on the original mechanical properties of the bare mesh, and good stability under physiological conditions. The biocompatibility of meshPCL-Gel was assessed by culturing BJ human fibroblasts on the device, up to 7 days. After 24 h, cells adhered to the nanofibrous substrate, and after 72 h their metabolic activity was about 70% with respect to control cells. The absence of detectable lactate dehydrogenase in the culture medium indicated that no necrosis induction occurred. Hence, the developed nanostructured coating provided the meshPCL-Gel device with chemical and topographical cues similar to the native extracellular matrix ones, that could be exploited for enhancing the biological response and, consequently, mesh integration, in abdominal wall hernia repair.

Microwave-assisted synthesis of the lipase-catalyzed ring-opening copolymerization of ε-caprolactone and ω-pentadecanolactone: Thermal and FTIR characterization

Microwave-assisted synthesis of the lipase-catalyzed ring opening polymerization of ε-caprolactone (ε-CL) and ω-pentadecanolactone (ω-PDL) monomers was studied. A series of P(CL-co-PDL), with different molar feed ratios, including (ε-CL/ω-PDL) 100/0, 75/25, 50/50, 25/75, and 0/100, were synthesized. The resulting polyesters were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The microwave-assisted polymerization of the monomers reached high conversions (91–95%) within 60 min. FTIR spectra showed the typical absorption bands of these polyesters. A very intense band in the carbonyl region, which was shifted from 1,720 cm−1 for PCL to 1,732 cm−1 for PPDL homopolymer, as well as peaks owing to methylene groups in the 2,990–2,850 cm−1 range. DSC results revealed that all polyester samples were semi-crystalline. Interestingly, the copolymers exhibited only one melting peak (Tm), and their Tm values linearly increased from 57°C to 95°C as PPDL concentration was increased. Thermal stability of polyesters also depended on PDL content; an increase in PDL concentration increases polymer degradation temperature (Td).

Collagen/PCL Nanofibers Electrospun in Green Solvent by DOE Assisted Process. An Insight into Collagen Contribution

Collagen, thanks to its biocompatibility, biodegradability and weak antigenicity, is widely used in dressings and scaffolds, also as electrospun fibers. Its mechanical stability can be improved by adding polycaprolactone (PCL), a synthetic and biodegradable aliphatic polyester. While previously collagen/PCL combinations were electrospun in solvents such as hexafluoroisopropanol (HFIP) or trifluoroethanol (TFE), more recently literature describes collagen/PCL nanofibers obtained in acidic aqueous solutions. A good morphology of the fibers represents in this case still a challenge, especially for high collagen/PCL ratios. In this work, thanks to preliminary rheological and physicochemical characterization of the solutions and to a Design of Experiments (DOE) approach on process parameters, regular and dimensionally uniform fibers were obtained with collagen/PCL ratios up to 1:2 and 1:1 w/w. Collagen ratio appeared relevant for mechanical strength of dry and hydrated fibers. WAXS and FTIR analysis showed that collagen denaturation is related both to the medium and to the electrospinning process. After one week in aqueous environment, collagen release was complete and a concentration dependent stimulatory effect on fibroblast growth was observed, suggesting the fiber suitability for wound healing. The positive effect of collagen on mechanical properties and on fibroblast biocompatibility was confirmed by a direct comparison of nanofiber performance after collagen substitution with gelatin.

Induced Periosteum-Mimicking Membrane with Cell Barrier and Multipotential Stromal Cell (MSC) Homing Functionalities

The current management of critical size bone defects (CSBDs) remains challenging and requires multiple surgeries. To reduce the number of surgeries, wrapping a biodegradable fibrous membrane around the defect to contain the graft and carry biological stimulants for repair is highly desirable. Poly(ε-caprolactone) (PCL) can be utilised to realise nonwoven fibrous barrier-like structures through free surface electrospinning (FSE). Human periosteum and induced membrane (IM) samples informed the development of an FSE membrane to support platelet lysate (PL) absorption, multipotential stromal cells (MSC) growth, and the prevention of cell migration. Although thinner than IM, periosteum presented a more mature vascular system with a significantly larger blood vessel diameter. The electrospun membrane (PCL3%-E) exhibited randomly configured nanoscale fibres that were successfully customised to introduce pores of increased diameter, without compromising tensile properties. Additional to the PL absorption and release capabilities needed for MSC attraction and growth, PCL3%-E also provided a favourable surface for the proliferation and alignment of periosteum- and bone marrow derived-MSCs, whilst possessing a barrier function to cell migration. These results demonstrate the development of a promising biodegradable barrier membrane enabling PL release and MSC colonisation, two key functionalities needed for the in situ formation of a transitional periosteum-like structure, enabling movement towards single-surgery CSBD reconstruction.

Preparation and characterization of poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/pullulan-gelatin electrospun nanofibers with shell-core structure

In this study, hydrophilic pullulan, which is favorable for cell adhesion, proliferation, and differentiation, was selected as a modifier for the preparation of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-co-4HB))/pullulan nanofibers via electrospinning to improve the biocompatibility of P(3HB-co-4HB) and increase the drug loading of composite fibers. Alkyl polyglycoside was used as the emulsifying agent to promote emulsification and stabilize the P(3HB-co-4HB)/pullulan composite solution. Drug-loading property of the nanofibers with a shell-core structure is increased because gelatin was not formed into fibers via electrospinning, thereby forming a stable drug-containing gelatin solution in the core layer. Finally, P(3HB-co-4HB)/pullulan-gelatin shell-core nanofibers were prepared. The intermolecular interaction, morphology, crystallization properties, mechanical properties, morphology, sustained release, and biocompatibility of composite nanofibers were characterized. Results show that the crystallization property of P(3HB-co-4HB)/pullulan composite nanofibers increases continuously with an increase in the pullulan content. As the pullulan content increases, the strain and stress of P(3HB-co-4HB)/pullulan nanofibers increase initially and decrease later. At the mass ratio of P(3HB-co-4HB) to pullulan of 10:2, P(3HB-co-4HB)/pullulan composite nanofibers exhibit a uniform morphology with an average diameter of 590 nm and porosity of 70.71%. At this mass ratio, the P(3HB-co-4HB)/pullulan-gelatin/drug shell-core structure, which sustained a release effect for more than 180 h, has potential applications as biomaterials without cytotoxicity.

Enhancement of hydrophilicity, biocompatibility and biodegradability of poly(ε-caprolactone) electrospun nanofiber scaffolds using poly(ethylene glycol) and poly(L-lactide-co-ε-caprolactone-co-glycolide) as additives for soft tissue engineering

In this study, poly(ε-caprolactone) (PCL) has been blended with a more hydrophilic poly(ethylene glycol) (PEG) and with a biocompatible block-co-polymer: poly(L-lactide-co-ε-caprolactone-co-glycolide) (PLCG) in order to improve hydrophilicity, biocompatibility and biodegradability of PCL. PCL and the blend solutions were subjected to electrospinning to produce nanofiber scaffolds by the addition of only 1 wt% of PEG and PLCG either singly or in combination in PCL to retain the mechanical properties of the scaffolds. PCL-PEG-PLCG ternary and two binary (PCL-PEG and PCL-PLCG) blend nanofiber scaffolds have been prepared for comparison. The resulting nanofibers showed a smooth and flaw-free surface and the diameter of the nanofibers displayed a normal distribution. The PCL-PEG nanofiber scaffold showed improved hydrophilicity [water contact angle (WCA) ∼84°] over pristine PCL (WCA ∼127°); while PCL-PLCG and PCL-PEG-PLCG scaffolds exhibited absolute wetting by water, likely due to high porosity. In vitro biocompatibility studies using gingival mesenchymal stem cells (gMSCs) suggested that, both the PCL and the blend scaffolds were biocompatible supporting cell-viability and growth of gMSCs following their seeding on these scaffolds. Biodegradation studies in phosphate buffer solution showed that the addition of PEG and PLCG in PCL increased the weight loss of scaffolds with time, indicating higher extent of biodegradation in the blend scaffolds and the weight loss followed the power law curve with time.

Hybrid cardiovascular sourced extracellular matrix scaffolds as possible platforms for vascular tissue engineering

The aim when designing a scaffold is to provide a supportive microenvironment for the native cells, which is generally achieved by structurally and biochemically imitating the native tissue. Decellularized extracellular matrix (ECM) possesses the mechanical and biochemical cues designed to promote native cell survival. However, when decellularized and reprocessed, the ECM loses its cell supporting mechanical integrity and architecture. Herein, we propose dissolving the ECM into a polymer/solvent solution and electrospinning it into a fibrous sheet, thus harnessing the biochemical cues from the ECM and the mechanical integrity of the polymer. Bovine aorta and myocardium were selected as ECM sources. Decellularization was achieved using sodium dodecyl sulfate (SDS), and the ECM was combined with polycaprolactone and hexafluoro-2-propanol for electrospinning. The scaffolds were seeded with human umbilical vein endothelial cells (HUVECs). The study found that the inclusion of aorta ECM increased the scaffold's wettability and subsequently lead to increased HUVEC adherence and proliferation. Interestingly, the inclusion of myocardium ECM had no effect on wettability or cell viability. Furthermore, gene expression and mechanical changes were noted with the addition of ECM. The results from this study show the vast potential of electrospun ECM/polymer bioscaffolds and their use in tissue engineering.

Modulating the Mechanical Properties of Electrospun PHB/PCL Materials by Using Different Types of Collectors and Heat Sealing

Two-component fibrous materials based on poly(3-hydroxybutyrate) (PHB, T_m = 160 °C) and poly(ε-caprolactone) (PCL, T_m = 60 °C) were successfully fabricated by dual-jet electrospinning of their separate spinning solutions. The desired alignment of the fibers that compose PHB/PCL mats was achieved by using three types of rotating collectors-drum (smooth), blade and grid. Additional fiber alignment in the direction of collector rotation was achieved by rotating at 2200 rpm. Moreover, the selected concentration of PCL spinning solution resulted in fibers with spindle-like defects along their length. Thus, "segment" sealing of the PHB (high-melting) fibers by the molten PCL (low-melting) fibers/defects sites was achieved after heating the PHB/PCL mats above the melting temperature (T_m) of PCL. The surface morphology, thermal behavior and mechanical properties of the PHB/PCL mats before and after thermal treatment were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and mechanical tests. The results indicated that regardless of the cutting direction of the specimens (0° or 90°), thermal treated PHB/PCL mats reveal enhanced mechanical properties. Therefore, this work provides an easily feasible route for the fabrication of electrospun PHB/PCL mats with tunable mechanical properties and improved performance.

Structure-properties relationship of chitosan/collagen films with potential for biomedical applications

Chitosan/collagen films were developed and characterized in order to assess the suitability of these films for biomedical applications. Hence, physicochemical, thermal, barrier and mechanical properties were analyzed and related to the film structure, which showed the prevalence of the triple helix of native collagen after the addition of chitosan. Furthermore, collagen fiber diameter changed from 3.9 ± 0.6 μm, for collagen films without chitosan, to 1.8 ± 0.5 μm, for collagen films with low molecular weight chitosan. These results suggested interactions between collagen and chitosan molecules, as observed by Fourier transform infrared (FTIR) analysis. Regarding film barrier properties, chitosan/collagen films showed a water vapor transmission rate around 1174 g m^-2 day^-1, suitable for biomedical applications such as wound healing. Additionally, biological tests confirmed that the chitosan/collagen films developed are suitable for biomedical applications.