Bioactive Electrospun Fibers: Fabrication Strategies and a Critical Review of Surface-Sensitive Characterization and Quantification

Janus Nanofibrous Patch with In Situ Grown Superlubricated Skin for Soft Tissue Repair with Inhibited Postoperative Adhesion

The patch with a superlubricated surface shows great potential for the prevention of postoperative adhesion during soft tissue repair. However, the existing patches suffer from the destruction of topography during superlubrication coating and lack of pro-healing capability. Herein, we demonstrate a facile and versatile strategy to develop a Janus nanofibrous patch (J-NFP) with antiadhesion and reactive oxygen species (ROS) scavenging functions. Specifically, sequential electrospinning is performed with initiators and CeO2 nanoparticles (CeNPs) embedded on the different sides, followed by subsurface-initiated atom transfer radical polymerization for grafting zwitterionic polymer brushes, introducing superlubricated skin on the surface of single nanofibers. The poly(sulfobetaine methacrylate) brush-grafted patch retains fibrous topography and shows a coefficient of friction of around 0.12, which is reduced by 77% compared with the pristine fibrous patch. Additionally, a significant reduction in protein, platelet, bacteria, and cell adhesion is observed. More importantly, the CeNPs-embedded patch enables ROS scavenging as well as inhibits pro-inflammatory cytokine secretion and promotes anti-inflammatory cytokine levels. Furthermore, the J-NFP can inhibit tissue adhesion and promote repair of both rat skin wounds and intrauterine injuries. The present strategy for developing the Janus patch exhibits enormous prospects for facilitating soft tissue repair.

Smart Electrospun Nanofibers from Short Peptidomimetics Based on Pyrrolo-pyrazole Scaffold

We prepared a small library of short peptidomimetics based on 3-pyrrolo-pyrazole carboxylate, a non-coded γ-amino acid, and glycine or alanine. The robust and eco-friendly synthetic approach adopted allows to obtain the dipeptides in two steps from commercial starting materials. This gives the possibility to shape these materials by electrospinning into micro- and nanofibers, in amounts required to be useful for coating surfaces of biomedical relevance. To promote high quality of electrospun fibers, different substitution patterns were evaluated, all for pure peptide fibers, free of any polymer or additive. The best candidate, which affords a homogeneous fibrous matrix, was prepared in larger amounts, and its biocompatibility was verified. This successful work is the first step to develop a new biomaterial able to produce pristine peptide-based nanofibers to be used as helpful component or stand-alone scaffolds for tissue engineering or for the surface modification of medical devices.

One-Pot Assembly of Drug-Eluting Silk Coatings with Applications for Nerve Regeneration

Clinical use of polymeric scaffolds for tissue engineering often suffers from their inability to promote strong cellular interactions. Functionalization with biomolecules may improve outcomes; however, current functionalization approaches using covalent chemistry or physical adsorption can lead to loss of biomolecule bioactivity. Here, we demonstrate a novel bottom-up approach for enhancing the bioactivity of poly(l-lactic acid) electrospun scaffolds though interfacial coassembly of protein payloads with silk fibroin into nanothin coatings. In our approach, protein payloads are first added into an aqueous solution with Bombyx mori-derived silk fibroin. Phosphate anions are then added to trigger coassembly of the payload and silk fibroin, as well as noncovalent formation of a payload-silk fibroin coating at poly(l-lactic) acid fiber surfaces. Importantly, the coassembly process results in homogeneous distribution of protein payloads, with the loading quantity depending on payload concentration in solution and coating time. This coassembly process yields greater loading capacity than physical adsorption methods, and the payloads can be released over time in physiologically relevant conditions. We also demonstrate that the coating coassembly process can incorporate nerve growth factor and that coassembled coatings lead to significantly more neurite extension than loading via adsorption in a rat dorsal root ganglia explant culture model.

Ultra-thin electrospun nanocomposite scaffold of poly (3-hydroxybutyrate)-chitosan/magnetic mesoporous bioactive glasses for bone tissue engineering applications

Bioglass is widely used in skeletal tissue engineering due to its outstanding bioactive properties. In the present study, magnetic mesoporous bioglass (MMBG) synthesized through the sol-gel method was incorporated into poly(3-hydroxybutyrate)-chitosan (PHB-Cs) solution and the resulting electrospun nanocomposite scaffolds were investigated and compared with MMBG free scaffold. The addition of 10 wt% MMBG has an outstanding effect on producing ultra-thin electrospun nanocomposite fibers due to its magnetic content (diameter of ≃128 nm). This improvement led to better mechanical properties, including an increase in both tensile modulus (up to ≃229 MPa) and tensile strength (to ≃4.95 MPa). Although the inclusion of MMBG slightly decreased the surface roughness of the nanofibrous scaffold (RMS from ≃197 to 154 nm), it could improve the wettability (WCA from ≃54 to 44°). This achievement has the potential to bring an enhancement in biomineralization and biological response. These outputs, combined with the observed increase in human osteoblast MG-63 cell viability (≃53 % improvement) as measured by MTT assay, DAPI, and SEM indicate prefer cell behavior of this nanocomposite structure. Additionally, the qualitative improvement in Alizarin Red staining and the quantitative enhancement of ALP secretion, serve as further evidence of the PHB-Cs/MMBG ultrathin nanofibers potential in bone tissue engineering.

Osteogenic potential of PHB-lignin/cellulose nanofiber electrospun scaffold as a novel bone regeneration construct

The electrospun scaffolds could mimic the highly hierarchical structure of extracellular matrix (ECM). Modern tissue engineering focuses on the properties of these microstructures, influencing the biological responses. This research investigates the variation of morphology, crystallinity, bioactivity, mechanical properties, contact angle, mass loss rate, roughness, cell behavior, biomineralization, and the efficacy of polyhydroxybutyrate (PHB)-based nanocomposite. Hence, 6 wt% lignin and 3 wt% cellulose nanofiber were added to the 9 wt% of PHB to prepare a novel electrospun nanocomposite structure (PLC). The outputs indicated more symmetrical circular fibers for PLC mat, higher surface roughness (326 to 389 nm), better hydrophilicity (120 to 60°), smaller crystal size (24 to 16 nm), and more reasonable biodegradability compared to PHB. These changes lead to the improvement of mechanical properties (toughness factor from 300 to 1100), cell behavior (viability from 60 to 100 %), bioactivity (from Ca/P ratio of 0.77 and 1.67), and higher level of alizarin red, and ALP enzyme secretion. Eventually, the osteopontin and alkaline phosphatase expression was also enhanced from ≃2.35 ± 0.15 and 2.1 ± 0.1 folds on the 1st day to ≃12.05 ± 0.35 and 7.95 ± 0.35 folds on 2nd week in PLCs. Accordingly, this newly developed structure could enhance biological responses and promote osteogenesis compared to PHB.

Engineered biomimetic micro/nano-materials for tissue regeneration

The incidence of tissue and organ damage caused by various diseases is increasing worldwide. Tissue engineering is a promising strategy of tackling this problem because of its potential to regenerate or replace damaged tissues and organs. The biochemical and biophysical cues of biomaterials can stimulate and induce biological activities such as cell adhesion, proliferation and differentiation, and ultimately achieve tissue repair and regeneration. Micro/nano materials are a special type of biomaterial that can mimic the microstructure of tissues on a microscopic scale due to its precise construction, further providing scaffolds with specific three-dimensional structures to guide the activities of cells. The study and application of biomimetic micro/nano-materials have greatly promoted the development of tissue engineering. This review aims to provide an overview of the different types of micro/nanomaterials, their preparation methods and their application in tissue regeneration.

Two dimensional (2D) materials and biomaterials for water desalination; structure, properties, and recent advances

BACKGROUND

An efficient solution to the global freshwater dilemma is desalination. MXene, Molybdenum Disulfide (MoS₂), Graphene Oxide, Hexagonal Boron Nitride, and Phosphorene are just a few examples of two-dimensional (2D) materials that have shown considerable promise in the development of 2D materials for water desalination. However, other promising materials for desalinating water are biomaterials. The benefits of bio-materials are their wide distribution, lack of toxicity, and superior capacity for water desalination.

METHODS

For the rational use of water and the advancement of sustainable development, it is of the utmost importance to research 2D-dimensional materials and biomaterials that are effective for water desalination. The scientific community has concentrated on wastewater remediation using bio-derived materials, such as nanocellulose, chitosan, bio-char, bark, and activated charcoal generated from plant sources, among the various endeavors to enhance access to clean water. Moreover, the 2D-materials and biomaterials may have ushered in a new age in the production of desalination materials and created a promising future.

RESULTS

The present review article focuses on and reviews the progress of 2D materials and biomaterials for water desalination. Their properties, surface, and structure, combined with water desalination applications, are highlighted. Further, the practicability and potential future directions of 2D materials and biomaterials are proposed. Thus, the current work provides information and discernments for developing novel 2D materials and biomaterials for wastewater desalination. Moreover, it aims to promote the contribution and advancement of materials for water desalination, fabrication, and industrial production.

Self-intensified synergy of a versatile biomimetic nanozyme and doxorubicin on electrospun fibers to inhibit postsurgical tumor recurrence and metastasis

Tumor-positive resection margins after surgery can result in tumor recurrence and metastasis. Although adjuvant postoperative radiotherapy and chemotherapy have been adopted in clinical practice, they lack efficacy and result in unavoidable side effects. Herein, a self-intensified in-situ therapy approach using electrospun fibers loaded with a biomimetic nanozyme and doxorubicin (DOX) is developed. The fabricated PEG-coated zeolite imidazole framework-67 (PZIF67) is demonstrated as a versatile nanozyme triggering reactions in cancer cells based on endogenous H₂O₂ and •O₂^-. The PZIF67-generated •OH induces reactive oxygen species (ROS) overload, implementing chemodynamic therapy (CDT). The O₂ produced by PZIF67 inhibits the expression of hypoxia-up-regulated proteins, thereby suppressing tumor progression. PZIF67 also catalyzes the degradation of glutathione, further disturbing the intracellular redox homeostasis and enhancing CDT. Furthermore, the introduced DOX not only kills cancer cells individually, but also replenishes the continuously consumed substrates for PZIF67-catalyzed reactions. The PZIF67-weakened drug resistance strengthens the cytotoxicity of DOX. The combined application of PZIF67 and DOX also suppresses metastasis-associated genes. Both in vitro and in vivo results demonstrate that the self-intensified synergy of PZIF67 and DOX on electrospun fibers efficiently prevents postsurgical tumor recurrence and metastasis, offering a feasible therapeutic regimen for operable malignant tumors.

Aligned electrospun fiber film loaded with multi-enzyme mimetic iridium nanozymes for wound healing

A film with elaborate microstructures that offers biomimetic properties and multi functionalities is highly desired in wound healing. Here, we develop an aligned hydrogel fiber film integrated with multi-active constituents to promote wound healing. Such fiber films are designed and constructed by photo-crosslinking the methacrylate gelatin (GelMA) doped with silver nanoparticles (Ag NPs) and iridium nanoparticles coated with polyvinylpyrrolidone (PVP-Ir NPs) in the precursor solution using electrospinning. The nature of GelMA hydrogel and the aligned arrangement of nanofibers endow the film with high-water content, self-degradability, improved bionic characteristics, oriented cell growth, and improved cell proliferation and migration. Moreover, the encapsulated nanozymes and Ag NPs offer the fiber film with superior reactive oxygen species (ROS) scavenging and antibacterial capability. The infected wound model shows that the multi-active hydrogel fiber film can reduce inflammation by killing bacteria and decomposing ROS, which accelerates the growth of new blood vessels and granulation tissue. Benefitting from these features, the versatile aligned GelMA fiber film demonstrates the clinically translational potential for wound healing.

Colorimetric Indicators Based on Anthocyanin Polymer Composites: A Review

This review explores the colorimetric indicators based on anthocyanin polymer composites fabricated in the last decade, in order to provide a comprehensive overview of their morphological and compositional characteristics and their efficacy in their various application fields. Notably, the structural properties of the developed materials and the effect on their performance will be thoroughly and critically discussed in order to highlight their important role. Finally, yet importantly, the current challenges and the future perspectives of the use of anthocyanins as components of colorimetric indicator platforms will be highlighted, in order to stimulate the exploration of new anthocyanin sources and the in-depth investigation of all the possibilities that they can offer. This can pave the way for the development of high-end materials and the expansion of their use to new application fields.

Influence of the Components and Orientation of Hydroxyapatite Fibrous Substrates on Osteoblast Behavior

Synthetic hydroxyapatite has good biocompatibility, bioactivity and osteoconductive ability because its chemical properties and biological properties are similar to those of bioapatite in bone tissue. Strontium-substituted hydroxyapatite has better degradability than hydroxyapatite and can both promote osteogenesis and inhibit adipogenesis in mesenchymal stem cells. Hence, hydroxyapatite and strontium-substituted hydroxyapatite are widely used as bone graft materials, cell carriers and drug/gene delivery carriers. In addition, osteoblasts cultured on aligned nanofibrous substrates had higher expression of osteogenesis-related genes than did those cultured on random nanofibrous substrates. However, to date, no study has explored the effects of the components and orientation of hydroxyapatite nanofibrous substrates on osteoblastic behavior. In this study, a random hydroxyapatite nanofibrous substrate (R-HANF), a random strontium-substituted hydroxyapatite nanofibrous substrate (R-SrHANF), an aligned hydroxyapatite nanofibrous substrate (A-HANF) and an aligned strontium-substituted hydroxyapatite nanofibrous substrate (A-SrHANF) were successfully fabricated by using the electrospinning technique. The effect of fiber composition on osteoblast-like MG63 cells was assessed by evaluating cell morphology, cell proliferation and osteogenesis-related gene expression. The results showed that MG63 cells cultured on A-SrHANF had higher osteogenesis-related gene expression than those cultured on A-HANF. Additionally, MG63 cells were cultured on R-SrHANF and A-SrHANF to evaluate the effects of fiber orientation on cell behavior. On A-SrHANF, the cells aligned along the direction of the nanofibers, with typical bipolar morphologies, and exhibited higher osteogenesis-related gene expression than cells on R-SrHANF. Hence, the components and orientation of hydroxyapatite nanofibrous substrates are critical parameters affecting the osteogenesis process.

Optimization and characterization of polyhydroxybutyrate/lignin electro-spun scaffolds for tissue engineering applications

The tissue engineering scaffolds requires efficient combination of materials, appropriate method of preparation, and precise characterization of final product. In this study, the optimal electrospinning process conditions of polyhydroxybutyrate (PHB) were investigated by Taguchi design. Then, the initial PHB solution characteristics in the presence of lignin were optimized and then electro-spun. In this regard, the uniformity of electro-spun nanofibers, observed by SEM, confirmed that 9 w/v % is the optimum concentration of PHB in Trifluoro acetic acid. Addition of 6 wt% of lignin to PHB, could alleviate both the brittleness and hydrophobicity of PHB, as DSC, XRD, and WCA results indicated decrement in crystallinity (from 46 to 39 %), crystal size (from 21.8 to 15.2 nm), and WCA (from 118 to 73°). On the other hand, FESEM results represented diameter reduction from 1318 ± 202.07 to 442 ± 111.04 nm, and transformation of nanofiber physical structure from ribbon-like to cylindrical fiber by adding lignin. In addition, the mechanical properties of PHB including elongation at break, toughness, young modulus, and tensile strength were also improved (up to twice) by adding lignin. Ultimately, reviewing the outputs of degradation, bioactivity, MG63 cell viability, proliferation, mineralization, and antioxidant activity confirm that PHB/lignin electrospun scaffold has potential application in tissue engineering.

Electrospun halloysite nanotube loaded polyhydroxybutyrate-starch fibers for cartilage tissue engineering

Articular cartilage is a connective load-bearing tissue with a low rate of regeneration due to slow metabolism. Fabricating tissue-like structure modified based on natural features can improve healing process. Fibrous scaffolds based on the composition of hydrophobic polyhydroxybutyrate (PHB) and hydrophilic starch reinforced using halloysite nanotubes (HNTs) with appropriate physico-chemical and biological properties was produced via electrospinning technique for long-term applications like cartilage regeneration. Textural properties were analyzed through SEM imaging that showed incorporating HNTs up to 2 wt% decreased mean fiber diameter to 158 ± 48 nm with larger pore size and appropriate porosity percentage. Moreover, the tensile strength was improved up to 4.21 ± 0.31 MPa after HNTs incorporation support chondrocyte cell growth. Furthermore, incorporating HNTs induced surface hydrophilicity and in vitro degradation. The biological assays both MTT assay and cell attachment of chondrocyte cells on 2 wt% HNTs incorporated into PHB-starch fibers indicated that HNTs incorporation can support cell growth and attachment without any toxicity for biomedical applications. To conclude, the obtained results demonstrated PHB-starch/HNTs fibrous scaffold could be potential for further experimental studies for tissue engineering applications like cartilage.

Three-dimensional, biomimetic electrospun scaffolds reinforced with carbon nanotubes for temporomandibular joint disc regeneration

Temporomandibular disorder (TMD) remained a huge clinical challenge, with high prevalence but limited, unstable, and only palliative therapeutic methods available. As one of the most vulnerable sites implicated in TMD, the temporomandibular joint disc (TMJD) displayed a complicated microstructure, region-specific fibrocartilaginous distribution, and poor regenerative property, which all further hindered its functional regeneration. To address the problem, with versatile and relatively simple electrospinning (ELS) technique, our study successfully fabricated a biomimetic, three-dimensional poly (ϵ-caprolactone) (PCL)/polylactide (PLA)/carbon nanotubes (CNTs) disc scaffold, whose biconcave gross anatomy and regionally anisotropic microstructure recapitulating those of the native disc. As in vitro results validated the superior mechanical, bioactive, and regenerative properties of the biomimetic scaffolds with optimal CNTs reinforcement, we further performed in vivo experiments. After verifying its biocompatibility and ectopic fibrochondrogenicity in nude mice subcutaneous implantation models, the scaffolds guided disc regeneration and subchondral bone protection were also confirmed orthotopically in rabbits TMJD defected areas, implying the pivotal role of morphological cues in contact-guided tissue regeneration. In conclusion, our work represents a significant advancement in complex, inhomogeneous tissue engineering, providing promising clinical solutions to intractable TMD ailments. STATEMENT OF SIGNIFICANCE: Complex tissue regeneration remains a huge scientific and clinical challenge. Although frequently implicated in temporomandibular joint disorder (TMD), functional regeneration of injured temporomandibular joint disc (TMJD) is extremely hard to achieve, mainly because of the complex anatomy and microstructure with regionally variant, anisotropic fiber alignments in the native disc. In this study, we developed the biomimetic electrospun scaffold with optimal CNTs reinforcement and regionally anisotropic fiber orientations. The excellent mechanical and bioactive properties were confirmed both in vitro and in vivo, effectively promoting defected discs regeneration in rabbits. Besides demonstrating the crucial role of morphological biomimicry in tissue engineering, our work also presents a feasible clinical solution for complex tissue regeneration.

Influence of photosensitizer concentration and polymer composition on photoinduced antimicrobial activity of PVA- and PVA-chitosan-based electrospun nanomaterials cross-linked with tailor-made silicon(IV) phthalocyanine

The ongoing effort to eradicate pathogenic bacteria and viruses is a major endeavor that requires development of new and innovative materials. Materials based on photodynamic action represent an emerging and attractive area of research, and therefore, a broad understanding of chemical design principles is required. In the present study, we investigated the antibacterial and antiviral activities of five different nanofibrous membranes composed of poly(vinyl alcohol) or poly(vinyl alcohol)-chitosan mixture cross-linked through silicon(IV)phthalocyanine derivative with the aim to identify the role of the carrier polymer and photosensitizers concentration on its efficacy. A straightforward cross-linking process was adopted to create a water-stable material with an almost uniform distribution of the fiber structure, as revealed by scanning electron microscopy. The results of the antimicrobial studies showed that the increase in the amount of chitosan in the polymer mixture, rather than the increase in the photosensitizer concentration, enhanced the activity of the material. Due to their visible light-triggered antimicrobial activity, the resulting materials provide valuable opportunities for both topical antimicrobial photodynamic therapy and the area of environmental remediation.

Polymer-Based Nanofiber-Nanoparticle Hybrids and Their Medical Applications

The search for higher-quality nanomaterials for medicinal applications continues. There are similarities between electrospun fibers and natural tissues. This property has enabled electrospun fibers to make significant progress in medical applications. However, electrospun fibers are limited to tissue scaffolding applications. When nanoparticles and nanofibers are combined, the composite material can perform more functions, such as photothermal, magnetic response, biosensing, antibacterial, drug delivery and biosensing. To prepare nanofiber and nanoparticle hybrids (NNHs), there are two primary ways. The electrospinning technology was used to produce NNHs in a single step. An alternate way is to use a self-assembly technique to create nanoparticles in fibers. This paper describes the creation of NNHs from routinely used biocompatible polymer composites. Single-step procedures and self-assembly methodologies are used to discuss the preparation of NNHs. It combines recent research discoveries to focus on the application of NNHs in drug release, antibacterial, and tissue engineering in the last two years.

Evaluation of the effects of starch on polyhydroxybutyrate electrospun scaffolds for bone tissue engineering applications

Efficient design for bone tissue engineering requires an understanding of the appropriate selection of biomimetic natural or synthetic materials and scalable fabrication technologies. In this research, poly (3-hydroxybutyrate) (PHB) and starch (5-15 wt%) as biological macromolecules were used to fabricate novel biomimetic scaffolds by electrospinning method. SEM results of electrospun scaffolds revealed bead-free nanofibers and three-dimensional homogenous structures with highly interconnected pores. Results of FTIR and Raman demonstrated that there were hydrogen bonds between the two polymers. The tensile strength of scaffolds was significantly improved by adding starch up to 10 wt%, from 3.05 to 15.54 MPa. In vitro degradation and hydrophilicity of the scaffolds were improved with the presence of starch. The viability and proliferation of MG-63 cells and alkaline phosphatase (ALP) activity were remarkably increased in the PHB-starch scaffolds compared to the PHB and control samples. The mineralization and calcium deposition of MG-63 cells were confirmed by alizarin red staining. It is concluded that PHB/starch electrospun scaffold could be a good candidate for bone tissue engineering applications.

JK-2 loaded electrospun membrane for promoting bone regeneration

Hydrogen sulfide (H₂S) has been as an essential gasotransmitter and a potential therapeutic approach for several biomedical treatments such as cardiovascular disorders, hypertension, and other diseases. The endogenous and exogenous H₂S also plays a crucial role in the bone anabolic process and a protective mechanism in cell signalling. In this study, we have utilized two types of polymers, polycaprolactone (PCL) and gelatin (Gel), for the fabrication of JK-2 (H₂S donor) loaded nanofibrous scaffold via electrospinning process for bone healing and bone tissue engineering. Comparing the PCL/Gel and PCL/Gel-JK-2 scaffolds, the latter demonstrated enhanced cell adhesion and proliferation capabilities. Furthermore, both experimental scaffolds have been subjected to an in vivo experiment for 4 and 8 weeks in a bone-defect model of a rabbit to determine their biological responses under physiological conditions. There was an obvious increase in bone regeneration in the PCL/Gel-JK-2 group compared to the control and PCL/Gel groups. These results indicate the use of PCL/Gel scaffolds loaded with JK-2 should be considered for possible bone regeneration.

Inducing Immunomodulatory Effects on Human Macrophages by Multifunctional NCO-sP(EO-stat-PO)/Gelatin Hydrogel Nanofibers

Endowing materials and scaffolds with immunomodulatory properties has evolved into a very active field of research. However, combining such effects with multifunctionality regarding cell adhesion and manipulation is still challenging due to the intricate nature of cell-substrate interactions that require fine-tuning of scaffold properties. Here, we reported electrospinning of a well-known biopolymer, gelatin, together with six-arm star-shaped poly(ethylene oxide-stat-propylene oxide) prepolymer with isocyanate end groups (NCO-sP(EO-stat-PO)) as a reactive prepolymer cross-linker. Covalent coupling of two components during and after processing yielded a network of hydrogel fibers that was remarkably stable under aqueous and also proteolytic conditions without the need for extra cross-linking, with a significant increase in stability with increasing NCO-sP(EO-stat-PO) content. When seeded with human macrophages, cells adhered and spread on the fibers and were found highly viable after 7 days of culture across all scaffolds. Furthermore, hybrid fibrous meshes upregulated the expression of a prohealing gene, CD206, while downregulating proinflammatory genes, IL-1β and IL-8. Markedly, NCO-sP(EO-stat-PO)-rich samples induced a significantly reduced release of proinflammatory cytokines, IL-1β, IL-6, and IL-8. Finally, we successfully conjugated IL-4 to NCO-sP(EO-stat-PO) that effectively steered macrophages into a prohealing M2 type, demonstrating additional and robust control over the immunomodulatory feature of the scaffolds.