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

Collagen/PCL electrospun fibers loaded with polyphenols: Curcumin and resveratrol comparison

Curcumin (Cur) and resveratrol (Rsv) have already been proposed for both anti-tumor and wound healing applications and contrasting results have been published regarding their anti- or pro-angiogenic activity; depending on the final application, an anti- or a pro-angiogenic activity is required. In the present study, a comparison of Cur and Rsv loaded electrospun fibers based on collagen and polycaprolactone (PCL) mixture was performed in order to make a contribution to understanding whether the two polyphenols have anti or pro-angiogenic activity. Despite their hydrophobic character, the two polyphenols affected morphology and wettability of the fibers, and Rsv-loaded fibers resulted larger and more quickly wettable. After hydration, collagen/PCL fibers loaded with both Cur and Rsv exhibited higher elongation and better deformation with respect to the unloaded fibers. Fourier transformed infrared spectroscopy and thermal analysis showed interactions between the polyphenols and collagen. Both fiber formulations resulted biocompatible with an increase of fibroblast number during 7 days of culture; confocal microscopy analyses demonstrated that Cur released by the fibers was internalized by the cells which remained vital and adherent. Chick embryo chorioallantoic membrane assay showed that both fibers had anti-angiogenic behavior, suggesting that an anti-cancer application more than a wound healing one could be envisaged.

Fabrication and characterisation of collagen/pullulan ultra-thin fibers by electrospinning

Collagen electrospun fibers are promising materials for food packaging and tissue engineering. The conventional electrospinning of collagen, however, is usually carried out by dissolving it in organic reagents, which are toxic. In this study, collagen/pullulan (COL/PUL) ultra-thin fibers were prepared by electrospinning using acetic acid as a solvent. Compared to the conventional preparation method, the proposed method is safe and does not produce toxic solvent residues. The introduction of PUL increased the degree of molecular entanglement in the solution, so the viscosity of the COL/PUL electrospun solution increased from 0.50 ± 0.01 Pa∙s to 4.40 ± 0.08 Pa∙s, and the electrical conductivity decreased from 1954.00 ± 1.00 mS/cm to 1372.33 ± 0.58 mS/cm. Scanning electron microscopy analysis confirmed that PUL improved the spinnability of COL, and smooth, defect-free COL/PUL ultra-thin fibers with diameters of 215.32 ± 40.56 nm and 240.97 ± 53.93 nm were successfully prepared at a viscosity of greater than 1.18 Pa∙s. As the proportion of PUL increased, intramolecular hydrogen bonds became the dominant interaction between COL and PUL. The intermolecular hydrogen bonding content decreased from 52.05 % to 36.45 %, and the intramolecular hydrogen bonding content increased from 46.11 % to 62.95 %. The COL was gradually unfolded, the content of α-helices decreased from 33.57 % to 25.91 % and the random coils increased from 34.22 % to 40.09 %. More than 36 % of the triple helix fraction of COL was retained by the COL/PUL ultra-thin fibers, whereas only 16 % of the triple helix fraction of COL was retained by the COL nanofibers prepared with 2.2.2-trifluoroethanol. These results could serve as a reference for the development of green food COL-based fibers.

Preparation and in vitro evaluation of cell adhesion and long-term proliferation of stem cells cultured on silibinin co-embedded PLGA/Collagen electrospun composite nanofibers

The present research aims to evaluate the efficacy of Silibinin-loaded mesoporous silica nanoparticles (Sil@MSNs) immobilized into polylactic-co-glycolic acid/Collagen (PLGA/Col) nanofibers on the in vitro proliferation of adipose-derived stem cells (ASCs) and cellular senescence. Here, the fabricated electrospun PLGA/Col composite scaffolds were coated with Sil@MSNs and their physicochemical properties were examined by FTIR, FE-SEM, and TGA. The growth, viability and proliferation of ASCs were investigated using various biological assays including PicoGreen, MTT, and RT-PCR after 21 days. The proliferation and adhesion of ASCs were supported by the biological and mechanical characteristics of the Sil@MSNs PLGA/Col composite scaffolds, according to FE- SEM. PicoGreen and cytotoxicity analysis showed an increase in the rate of proliferation and metabolic activity of hADSCs after 14 and 21 days, confirming the initial and controlled release of Sil from nanofibers. Gene expression analysis further confirmed the increased expression of stemness markers as well as hTERT and telomerase in ASCs seeded on Sil@MSNs PLGA/Col nanofibers compared to the control group. Ultimately, the findings of the present study introduced Sil@MSNs PLGA/Col composite scaffolds as an efficient platform for long-term proliferation of ASCs in tissue engineering.

In vitro and in vivo studies of Syzygium cumini-loaded electrospun PLGA/PMMA/collagen nanofibers for accelerating topical wound healing

This work aims to develop plant extract-loaded electrospun nanofiber as an effective wound dressing scaffolds for topical wound healing. Electrospun nanofibers were fabricated from Syzygium cumini leaf extract (SCLE), poly(lactic-co-glycolic acid) (PLGA), poly(methyl methacrylate) (PMMA), collagen and glycine. Electrospinning conditions were optimized to allow the formation of nanosized and uniform fibers that display smooth surface. Morphology and swelling behavior of the formed nanofibers were studied. In addition, the antibacterial activity of the nanofibers against multidrug-resistant and human pathogens was assessed by agar-well diffusion. Results showed that nanofibers containing Syzygium cumini extract at concentrations of 0.5 and 1% w/v exhibited greater antibacterial activity against the tested Gram-positive (i.e., Staphylococcus aureus, Candida albicans, Candida glabrata and Bacillus cereus) and Gram-negative (i.e., Salmonella paratyphi and Escherichia coli) pathogens compared to the same concentrations of the plain extract. Furthermore, in vivo wound healing was evaluated in Wistar rats over a period of 14 days. In vivo results demonstrated that nanofiber mats containing SCLE and collagen significantly improved wound healing within two weeks, compared to the control untreated group. These findings highlight the potential of fabricated nanofibers in accelerating wound healing and management of topical acute wounds.

Recent trends in the application of protein electrospun fibers for loading food bioactive compounds

Electrospun fibers (EFs) have emerged as promising one-dimensional materials for a myriad of research/commercial applications due to their outstanding structural and physicochemical features. Polymers of either synthetic or natural precursors are applied to design EFs as carriers for bioactive compounds. For engineering food systems, it is crucial to exploit polymers characterized by non-toxicity, non-immunogenicity, biocompatibility, slow/controllable biodegradability, and structural integrity. The unique attributes of protein-based biomaterials endow a wide diversity of desirable features to EFs for meeting the requirements of advanced food/biomedical applications. In this review paper, after an overview on electrospinning, different protein materials (plant- and animal-based) as biodegradable/biocompatible building blocks for designing EFs will be highlighted. The potential application of protein-based EFs in loading bioactive compounds with the intention to inspire interests in both academia and industry will be summarized. This review concludes with a discussion of prevailing challenges in using protein EFs for the bioactive vehicle development.

Fabrication of blended nanofibrous cardiac patch transplanted with TGF-β3 and human umbilical cord MSCs-derived exosomes for potential cardiac regeneration after acute myocardial infarction

Acute myocardial infarction (AMI) is a common cardiovascular condition that progressively results in heart failure. In the present study, we have designed to load transforming growth factor beta 3 (TGF-β3) and cardio potential exosomes into the blended polycaprolactone/type I collagen (PCL/COL-1) nanofibrous patch (Exo@TGF-β3@NFs) and examined its feasibility for cardiac repair. The bioactivity of the developed NFs towards the migration and proliferation of human umbilical vein endothelial cells was determined using in vitro cell compatibility assays. Additionally, Exo@TGF-β3/NFs showed up-regulation of genes involved in angiogenesis and mesenchymal differentiations in vitro. The in vivo experiments performed 4 weeks after transplantation showed that the Exo@TGF-β3@NFs had a higher LV ejection fraction and fraction shortening functions. Subsequently, it has been determined that Exo@TGF-β3@NFs significantly reduced AMI size and fibrosis and increased scar thickness. The developed NFs approach will become a useful therapeutic approach for the treatment of AMI.

Breast Tissue Reconstruction Using Polycaprolactone Ball Scaffolds in a Partial Mastectomy Pig Model

BACKGROUND

Breast cancer patients suffer from lowered quality of life (QoL) after surgery. Breast conservancy surgery (BCS) such as partial mastectomy is being practiced and studied as an alternative to solve this problem. This study confirmed breast tissue reconstruction in a pig model by fabricating a 3-dimensional (3D) printed Polycaprolactone spherical scaffold (PCL ball) to fit the tissue resected after partial mastectomy.

METHODS

A 3D printed Polycaprolactone spherical scaffold with a structure that can help adipose tissue regeneration was produced using computer-aided design (CAD). A physical property test was conducted for optimization. In order to enhance biocompatibility, collagen coating was applied and a comparative study was conducted for 3 months in a partial mastectomy pig model.

RESULTS

In order to identify adipose tissue and fibroglandular tissue, which mainly constitute breast tissue, the degree of adipose tissue and collagen regeneration was confirmed in a pig model after 3 months. As a result, it was confirmed that a lot of adipose tissue was regenerated in the PCL ball, whereas more collagen was regenerated in the collagen-coated Polycaprolactone spherical scaffold (PCL-COL ball). In addition, as a result of confirming the expression levels of TNF-a and IL-6, it was confirmed that PCL ball showed higher levels than PCL-COL ball.

CONCLUSION

Through this study, we were able to confirm the regeneration of adipose tissue through a 3-dimensional structure in a pig model. Studies were conducted on medium and large-sized animal models for the final purpose of clinical use and reconstruction of human breast tissue, and the possibility was confirmed.

The Mechanical Properties of Blended Fibrinogen:Polycaprolactone (PCL) Nanofibers

Electrospinning is a process to produce versatile nanoscale fibers. In this process, synthetic and natural polymers can be combined to produce novel, blended materials with a range of physical, chemical, and biological properties. We electrospun biocompatible, blended fibrinogen:polycaprolactone (PCL) nanofibers with diameters ranging from 40 nm to 600 nm, at 25:75 and 75:25 blend ratios and determined their mechanical properties using a combined atomic force/optical microscopy technique. Fiber extensibility (breaking strain), elastic limit, and stress relaxation times depended on blend ratios but not fiber diameter. As the fibrinogen:PCL ratio increased from 25:75 to 75:25, extensibility decreased from 120% to 63% and elastic limit decreased from a range between 18% and 40% to a range between 12% and 27%. Stiffness-related properties, including the Young's modulus, rupture stress, and the total and relaxed, elastic moduli (Kelvin model), strongly depended on fiber diameter. For diameters less than 150 nm, these stiffness-related quantities varied approximately as D-2; above 300 nm the diameter dependence leveled off. 50 nm fibers were five-ten times stiffer than 300 nm fibers. These findings indicate that fiber diameter, in addition to fiber material, critically affects nanofiber properties. Drawing on previously published data, a summary of the mechanical properties for fibrinogen:PCL nanofibers with ratios of 100:0, 75:25, 50:50, 25:75 and 0:100 is provided.

Electrospun nanofibres in drug delivery: advances in controlled release strategies

Emerging drug-delivery systems demand a controlled or programmable or sustained release of drug molecules to improve therapeutic efficacy and patient compliance. Such systems have been heavily investigated as they offer safe, accurate, and quality treatment for numerous diseases. Amongst newly developed drug-delivery systems, electrospun nanofibres have emerged as promising drug excipients and are coming up as promising biomaterials. The inimitable characteristics of electrospun nanofibres in terms of their high surface-to-volume ratio, high porosity, easy drug encapsulation, and programmable release make them an astounding drug-delivery vehicle.

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.

Electro Fluid Dynamics: A Route to Design Polymers and Composites for Biomedical and Bio-Sustainable Applications

In the last two decades, several processes have been explored for the development of micro and/or nanostructured substrates by sagely physically and/or chemically manipulating polymer materials. These processes have to be designed to overcome some of the limitations of the traditional ones in terms of feasibility, reproducibility, and sustainability. Herein, the primary aim of this work is to focus on the enormous potential of using a high voltage electric field to manipulate polymers from synthetic and/or natural sources for the fabrication of different devices based on elementary units, i.e., fibers or particles, with different characteristic sizes—from micro to nanoscale. Firstly, basic principles and working mechanisms will be introduced in order to correlate the effect of selected process parameters (i.e., an applied voltage) on the dimensional features of the structures. Secondly, a comprehensive overview of the recent trends and potential uses of these processes will be proposed for different biomedical and bio-sustainable application areas.

Grafting of Methyl Methacrylate onto Gelatin Initiated by Tri-Butylborane-2,5-Di-Tert-Butyl-p-Benzoquinone System

Graft gelatin and poly(methyl methacrylate) copolymers were synthesized in the presence of the tributylborane—2,5-di-tert-butyl-p-benzoquinone (2,5-DTBQ) system. The molecular weight parameters and morphology of the polymer indicate that it has a cross-linked structure. Obtained data confirm the simultaneous formation of a copolymer in two ways: “grafting from” and “grafting to”. It leads to the cross-linked structure of a copolymer. This structure was not obtained for copolymers synthesized in the presence of other initiating systems: azobisisobutyronitrile; tributylborane; azobisisobutyronitrile and tributylborane; azobisisobutyronitrile, tributylborane, and 2,5-di-tert-butyl-p-benzoquinone. In these cases, the possibility of the formation of the copolymer, simultaneously in two ways, was excluded. Graft gelatin and poly(methyl methacrylate) copolymers synthesized in the presence of the tributylborane—2,5-di-tert-butyl-p-benzoquinone system are promising in terms of their use in scaffold technologies due to the three-dimensional mesh structure, providing a high regenerative potential of materials.

Nanofiber Polymers for Coating Titanium-Based Biomedical Implants

The excellent combination of properties has seen a steep increase in the demand for titanium (Ti)-based material as biomedical implant devices. However, some features that promote biocompatibility are found to be lacking in Ti implants. The use of polymer nanofiber (NF) coating on the surfaces of the implants has been proven to remedy these setbacks. In particular, electrospun NFs are versatile as natural extracellular matrix mimics and as facilitators in the biocompatibility function of Ti-based implants. Therefore, various properties of Ti implants coated with polymer NFs and the correlations among these properties are explored in this review. Synthetic polymers are favorable in tissue engineering applications because they are biocompatible and have low toxicity and degradation rates. Several approved synthetic polymers and polymer hybrids have been electrospun onto Ti implant surfaces to successfully improve the biomedical applicability of the implants with regard to their physical (including diameter and porosity), chemical (including corrosion resistance), mechanical (including elastic modulus, strength and ductility) and biological properties (including tissue integration, antimicrobial and cytotoxicity).

Protein-Based Systems for Topical Antibacterial Therapy

Recently, proteins are gaining attention as potential materials for antibacterial therapy. Proteins possess beneficial properties such as biocompatibility, biodegradability, low immunogenic response, ability to control drug release, and can act as protein-mimics in wound healing. Different plant- and animal-derived proteins can be developed into formulations (films, hydrogels, scaffolds, mats) for topical antibacterial therapy. The application areas for topical antibacterial therapy can be wide including bacterial infections in the skin (e.g., acne, wounds), eyelids, mouth, lips, etc. One of the major challenges of the healthcare system is chronic wound infections. Conventional treatment strategies for topical antibacterial therapy of infected wounds are inadequate, and the development of newer and optimized formulations is warranted. Therefore, this review focuses on recent advances in protein-based systems for topical antibacterial therapy in infected wounds. The opportunities and challenges of such protein-based systems along with their future prospects are discussed.

Biomaterials for Soft Tissue Repair and Regeneration: A Focus on Italian Research in the Field

Tissue repair and regeneration is an interdisciplinary field focusing on developing bioactive substitutes aimed at restoring pristine functions of damaged, diseased tissues. Biomaterials, intended as those materials compatible with living tissues after in vivo administration, play a pivotal role in this area and they have been successfully studied and developed for several years. Namely, the researches focus on improving bio-inert biomaterials that well integrate in living tissues with no or minimal tissue response, or bioactive materials that influence biological response, stimulating new tissue re-growth. This review aims to gather and introduce, in the context of Italian scientific community, cutting-edge advancements in biomaterial science applied to tissue repair and regeneration. After introducing tissue repair and regeneration, the review focuses on biodegradable and biocompatible biomaterials such as collagen, polysaccharides, silk proteins, polyesters and their derivatives, characterized by the most promising outputs in biomedical science. Attention is pointed out also to those biomaterials exerting peculiar activities, e.g., antibacterial. The regulatory frame applied to pre-clinical and early clinical studies is also outlined by distinguishing between Advanced Therapy Medicinal Products and Medical Devices.