Recent Advances in Centrifugal Spinning and Their Applications in Tissue Engineering

Biopolymer based Fibrous Aggregate Materials for Diagnosis and Treatment: Design, Manufacturing, and Applications

Biopolymer-based fibrous aggregate materials (BFAMs) have gained increasing attention in biomedicine due to their excellent biocompatibility, processability, biodegradability, and multifunctionality. Especially, the medical applications of BFAMs demand advanced structure, performance, and function, which conventional trial-and-error methods struggle to provide. This necessitates the rational selection of materials and manufacturing methods to design BFAMs with various intended functions and structures. This review summarizes the current progress in raw material selection, structural and functional design, processing technology, and application of BFAMs. Additionally, the challenges encountered during the development of BFAMs are discussed, along with perspectives for future research offered.

Fabrication of pullulan-chitosan fiber membranes for enhanced hemostatic applications

Pullulan-based fibers blended with chitosan (Chi) were developed using a rotational spinning method for potential biomedical applications. Aqueous precursor formulations containing 15 % by weight in pullulan and varying Chi concentrations (6 % and 7 %) were optimized to produce nanofibers at elevated temperatures and rotational speeds exceeding 7 k rpm. The highest fiber production yields of approximately 90 % and 65 % were achieved at 13 k rpm for the 6 % and 7 % Chi formulations, respectively. The pullulan-chitosan fibers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, dynamic mechanical analyzer, powder X-ray diffraction, and rheological property measurements. Morphological analyses revealed nanometric fiber diameters and a decrease in bead formation with increasing rotational speeds. Thermal stability studies, conducted via thermogravimetric and differential thermal analyses, showed that the composite fibers exhibited intermediate degradation behaviors between their individual polymer components, indicating good integration of Chi into the pullulan matrix. Elemental analysis confirmed the successful incorporation of Chi into the fibers, with nitrogen content closely matching theoretical predictions. Functional assessments demonstrated the hemocompatibility of the Pull-Chi fibers with hemolysis rates below 1 %. Additionally, the fibers exhibited superior hemostatic potential, effectively promoting blood clotting in vitro testing. These findings underscore the promise of Pull-Chi fibers as multifunctional biomaterials for applications in wound healing and tissue engineering. Future studies involving animal models are warranted to validate their clinical potential.

Preparation of sodium alginate antibacterial porous composite pads embedded with centrifugally spun nanofibers by freeze-drying and recasting for active food packaging

In this study, nanofibers composed of ethyl cellulose (EC)/polyethylene oxide (PEO) impregnated with tea polyphenol (TP) were fabricated by the centrifugal spinning method. Subsequently, these nanofibers were incorporated into sodium alginate (SA) to generate porous composite pads with varying fiber contents. The porous composite pads were comprehensively characterized. The findings indicate that the nanofiber structure of the porous composite pads is maintained, the porosity of the porous composite pads ranges from 16 % to 28 %, the water vapor transfer rate decreases as the fiber addition increases, and the thermal stability improves. Additionally, the pads demonstrated enhanced slow-release characteristics, and the cumulative TP release reached 70 % to 81.44 % within 120 h. All the porous composite pads could effectively inhibit the growth of Staphylococcus aureus and Escherichia coli, and the inhibition rates of the two bacteria were 99.69 % and 99.54 % respectively, highlighting their potential application in active food packaging.

Collagen as a biomaterial for skin wound healing: From structural characteristics to the production of devices for tissue engineering

Collagen is an abundant component in the human body and plays a fundamental role in the integrity and function of various tissues, including skin, bones, joints, and connective tissues. This natural polymer also contributes to physiological balance and individual health. Within this context, this article reviews the structure of collagen, describing intrinsic characteristics that range from its molecular composition to its organization into bundles. Additionally, the review highlights some of the applications of collagen in tissue engineering, particularly its mimicry of the skin's extracellular matrix. For this review, searches were performed in PubMed, Scopus, and Web of Sciences. The inclusion criteria were established based on the relevance of the studies for the objectives of the review and methodological quality. After selection of the articles, a critical analysis of their content was conducted and the information was synthesized and presented concisely. Analysis of the properties of collagen revealed its key importance for the design of bioactive materials in regenerative applications. However, challenges such as the need for improvement of the integration of implanted materials and a better understanding of the underlying biological processes remain.

Evaluation of Polymeric Micro/Nanofibrous Hybrid Scaffolds Prepared via Centrifugal Nozzleless Spinning for Tissue Engineering Applications

We compared the applicability of 3D fibrous scaffolds, produced by our patented centrifugal spinning technology, in soft tissue engineering. The scaffolds were prepared from four different biocompatible and biodegradable thermoplastics, namely, polylactide (PLA), polycaprolactone (PCL), poly(3-hydroxybutyrate) (PHB), and poly(1,4-butylene succinate) (PBS) and their blends. The combined results of SEM and BET analyses revealed an internal hierarchically organized porosity of the polymeric micro/nanofibers. Both nanoporosity and capillary effect are crucial for the water retention capacity of scaffolds designed for tissue engineering. The increased surface area provided by nanoporosity enhances water retention, while the capillary effect facilitates the movement of water and nutrients within the scaffolds. When the scaffolds were seeded with adipose-derived stem cells (ASCs), the ingrowth of these cells was the deepest in the PLA/PCL 13.5/4 (w/w) composite scaffolds. This result is consistent with the relatively large pore size in the fibrous networks, the high internal porosity, and the large specific surface area found in these scaffolds, which may therefore be best suited as a component of adipose tissue substitutes that could reduce postoperative tissue atrophy. Adipose tissue constructs produced in this way could be used in the future instead of conventional fat grafts, for example, in breast reconstruction following cancer ablation.

Processing and Properties of Polyhydroxyalkanoate/ZnO Nanocomposites: A Review of Their Potential as Sustainable Packaging Materials

The escalating environmental concerns associated with conventional plastic packaging have accelerated the development of sustainable alternatives, making food packaging a focus area for innovation. Bioplastics, particularly polyhydroxyalkanoates (PHAs), have emerged as potential candidates due to their biobased origin, biodegradability, and biocompatibility. PHAs stand out for their good mechanical and medium gas permeability properties, making them promising materials for food packaging applications. In parallel, zinc oxide (ZnO) nanoparticles (NPs) have gained attention for their antimicrobial properties and ability to enhance the mechanical and barrier properties of (bio)polymers. This review aims to provide a comprehensive introduction to the research on PHA/ZnO nanocomposites. It starts with the importance and current challenges of food packaging, followed by a discussion on the opportunities of bioplastics and PHAs. Next, the synthesis, properties, and application areas of ZnO NPs are discussed to introduce their potential use in (bio)plastic food packaging. Early research on PHA/ZnO nanocomposites has focused on solvent-assisted production methods, whereas novel technologies can offer additional possibilities with regard to industrial upscaling, safer or cheaper processing, or more specific incorporation of ZnO NPs in the matrix or on the surface of PHA films or fibers. Here, the use of solvent casting, melt processing, electrospinning, centrifugal fiber spinning, miniemulsion encapsulation, and ultrasonic spray coating to produce PHA/ZnO nanocomposites is explained. Finally, an overview is given of the reported effects of ZnO NP incorporation on thermal, mechanical, gas barrier, UV barrier, and antimicrobial properties in ZnO nanocomposites based on poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). We conclude that the functionality of PHA materials can be improved by optimizing the ZnO incorporation process and the complex interplay between intrinsic ZnO NP properties, dispersion quality, matrix-filler interactions, and crystallinity. Further research regarding the antimicrobial efficiency and potential migration of ZnO NPs in food (simulants) and the End-of-Life will determine the market potential of PHA/ZnO nanocomposites as active packaging material.

Biomimetic fiber/hydrogel composite scaffolds based on chitosan hydrogel and surface modified PCL chopped-microfibers

Hydrogel/fiber composites have received wide attention as tissue engineering scaffolds due to the outstanding properties of fibers and hydrogels. In the current research, a hydrogel/fiber composite scaffold was made based on chitosan-modified polycaprolactone (PCL) microfibers and chitosan hydrogel as a binder. The presence of chitosan as a modifier on the surface of fibers and as a binder between fibers can create scaffolds with excellent structural and mechanical properties. To this end, the three-dimensional microfibers were first functionalized with amine groups. Then, the chitosan chains were attached to the fibers by an aldehyde coupling agent and Schiff base reaction. FTIR and Raman spectroscopies corroborated that chitosan was successfully immobilized on PCL fibers. Chitosan-modified fibers were molded with chitosan solutions of various concentrations and the prepared composite scaffolds were stabilized using ionic crosslinking. The obtained composites represented a porous 3D structure with highly interconnected pores. The compressive modulus increased by 19 and 2.7 folds and the tensile modulus was augmented by 28 and 4 folds, in respective dry and swollen states with increasing hydrogel concentration from 0.1 to 1 %. Hydrogel/fiber composites were able to preserve cell viability, and increasing the hydrogel proportion increased adhesion, proliferation and penetration of cells into the scaffold.

Advances in Light-Responsive Smart Multifunctional Nanofibers: Implications for Targeted Drug Delivery and Cancer Therapy

Over the last decade, scientists have shifted their focus to the development of smart carriers for the delivery of chemotherapeutics in order to overcome the problems associated with traditional chemotherapy, such as poor aqueous solubility and bioavailability, low selectivity and targeting specificity, off-target drug side effects, and damage to surrounding healthy tissues. Nanofiber-based drug delivery systems have recently emerged as a promising drug delivery system in cancer therapy owing to their unique structural and functional properties, including tunable interconnected porosity, a high surface-to-volume ratio associated with high entrapment efficiency and drug loading capacity, and high mass transport properties, which allow for controlled and targeted drug delivery. In addition, they are biocompatible, biodegradable, and capable of surface functionalization, allowing for target-specific delivery and drug release. One of the most common fiber production methods is electrospinning, even though the relatively two-dimensional (2D) tightly packed fiber structures and low production rates have limited its performance. Forcespinning is an alternative spinning technology that generates high-throughput, continuous polymeric nanofibers with 3D structures. Unlike electrospinning, forcespinning generates fibers by centrifugal forces rather than electrostatic forces, resulting in significantly higher fiber production. The functionalization of nanocarriers on nanofibers can result in smart nanofibers with anticancer capabilities that can be activated by external stimuli, such as light. This review addresses current trends and potential applications of light-responsive and dual-stimuli-responsive electro- and forcespun smart nanofibers in cancer therapy, with a particular emphasis on functionalizing nanofiber surfaces and developing nano-in-nanofiber emerging delivery systems for dual-controlled drug release and high-precision tumor targeting. In addition, the progress and prospective diagnostic and therapeutic applications of light-responsive and dual-stimuli-responsive smart nanofibers are discussed in the context of combination cancer therapy.

Electrospun Polymeric Nanofibers: Current Trends in Synthesis, Surface Modification, and Biomedical Applications

Electrospun polymeric nanofibers are essential in various fields for various applications because of their unique properties. Their features are similar to extracellular matrices, which suggests them for applications in healthcare fields, such as antimicrobials, tissue engineering, drug delivery, wound healing, bone regeneration, and biosensors. This review focuses on the synthesis of electrospun polymeric nanofibers, their surface modification, and their biomedical applications. Nanofibers can be fabricated from both natural and synthetic polymers and their composites. Even though they mimic extracellular matrices, their surface features (physicochemical characteristics) are not always capable of fulfilling the purpose of the target application. Therefore, they need to be improved via surface modification techniques. Both needle-based and needleless electrospinning are thoroughly discussed. Various techniques and setups employed in each method are also reviewed. Furthermore, pre- and postspinning modification approaches for electrospun nanofibers, including instrument design and the modification features for targeted biomedical applications, are also extensively discussed. In this way, the remarkable potential of electrospun polymeric nanofibers can be highlighted to reveal future research directions in this dynamic field.

Preparation of CNT/CNF/PDMS/TPU Nanofiber-Based Conductive Films Based on Centrifugal Spinning Method for Strain Sensors

Flexible conductive films are a key component of strain sensors, and their performance directly affects the overall quality of the sensor. However, existing flexible conductive films struggle to maintain high conductivity while simultaneously ensuring excellent flexibility, hydrophobicity, and corrosion resistance, thereby limiting their use in harsh environments. In this paper, a novel method is proposed to fabricate flexible conductive films via centrifugal spinning to generate thermoplastic polyurethane (TPU) nanofiber substrates by employing carbon nanotubes (CNTs) and carbon nanofibers (CNFs) as conductive fillers. These fillers are anchored to the nanofibers through ultrasonic dispersion and impregnation techniques and subsequently modified with polydimethylsiloxane (PDMS). This study focuses on the effect of different ratios of CNTs to CNFs on the film properties. Research demonstrated that at a 1:1 ratio of CNTs to CNFs, with TPU at a 20% concentration and PDMS solution at 2 wt%, the conductive films crafted from these blended fillers exhibited outstanding performance, characterized by electrical conductivity (31.4 S/m), elongation at break (217.5%), and tensile cycling stability (800 cycles at 20% strain). Furthermore, the nanofiber-based conductive films were tested by attaching them to various human body parts. The tests demonstrated that these films effectively respond to motion changes at the wrist, elbow joints, and chest cavity, underscoring their potential as core components in strain sensors.

Characterizations of Centrifugal Electrospun Polyvinyl Alcohol/Sodium Alginate/Tamanu Oil/Silver Nanoparticles Wound Dressing

Known for its water solubility, flexibility, strong adhesion, and eco-friendly nature, polyvinyl alcohol (PVA) is widely used in various industries. In the medical field, it is used for applications such as creating bandages and orthopaedic devices. Incorporating sodium alginate (SA) into PVA membranes enhances their structural integrity, breathability, and permeability, thereby minimising the risk of cellular damage in the wound zone. Moreover, the addition of tamanu oil (C alophyllum inophyllum L.) and silver nanoparticles, both of which are known for their antibacterial properties and benefits in traditional wound healing, further enhances the membranes' wound-healing effectiveness. Following production, the membranes undergo a series of tests designed to evaluate their physical properties as well as their antioxidant and antibacterial capabilities. Subsequently, in vitro testing is conducted using human skin cells; experiments on Wistar rats are then performed. Numerous experiments have consistently demonstrated that the performance of polyvinyl alcohol/sodium alginate/tamanu oil (PVA/SA/Oil) membrane is superior to that of polyvinyl alcohol/sodium alginate/tamanu oil/silver nanoparticles (PVA/SA/Oil/Ag NP) membrane. Specifically, the polyvinyl alcohol/sodium alginate (PVA/SA) combination exhibits an impressive wound-healing rate of 98.82% after 15 days, with cells maintaining a high viability of 92% in a nourishing environment. Moreover, these membranes exhibit exceptional resistance to the oxidation of free radicals, surpassing the 70% threshold, and they possess antibacterial activity against Staphylococcus aureus subsp. aureus in vitro. Based on the obtained results, the nanofiber membranes composed of polyvinyl alcohol/ alginate/ tamanu oil, with or without silver nanoparticles, have shown potential as wound dressings in the wound care discipline.

A Review of the Preparation of Porous Fibers and Porous Parts by a Novel Micro-Extrusion Foaming Technique

This review introduces an innovative technology termed "Micro-Extrusion Foaming (MEF)", which amalgamates the merits of physical foaming and 3D printing. It presents a groundbreaking approach to producing porous polymer fibers and parts. Conventional methods for creating porous materials often encounter obstacles such as the extensive use of organic solvents, intricate processing, and suboptimal production efficiency. The MEF technique surmounts these challenges by initially saturating a polymer filament with compressed CO2 or N2, followed by cell nucleation and growth during the molten extrusion process. This technology offers manifold advantages, encompassing an adjustable pore size and porosity, environmental friendliness, high processing efficiency, and compatibility with diverse polymer materials. The review meticulously elucidates the principles and fabrication process integral to MEF, encompassing the creation of porous fibers through the elongational behavior of foamed melts and the generation of porous parts through the stacking of foamed melts. Furthermore, the review explores the varied applications of this technology across diverse fields and imparts insights for future directions and challenges. These include augmenting material performance, refining fabrication processes, and broadening the scope of applications. MEF technology holds immense potential in the realm of porous material preparation, heralding noteworthy advancements and innovations in manufacturing and materials science.

Attributes of Nanomaterials and Nanotopographies for Improved Bone Tissue Engineering and Regeneration

Bone tissue engineering (BTE) is a multidisciplinary area that can solve the limitation of conventional grafting methods by developing viable and biocompatible bone replacements. The three essential components of BTE, i.e., Scaffold material and Cells and Growth factors altogether, facilitate support and guide for bone formation, differentiation of the bone tissues, and enhancement in the cellular activities and bone regeneration. However, there is a scarcity of the appropriate materials that can match the mechanical property as well as functional similarity to native tissue, considering the bone as hard tissue. In such scenarios, nanotechnology can be leveraged upon to achieve the desired aspects of BTE, and that is the key point of this review article. This review article examines the significant areas of nanotechnology research that have an impact on regeneration of bone: (a) scaffold with nanomaterials helps to enhance physicochemical interactions, biocompatibility, mechanical stability, and attachment; (b) nanoparticle-based approaches for delivering bioactive chemicals, growth factors, and genetic material. The article begins with the introduction of components and healing mechanisms of bone and the factors associated with them. The focus of this article is on the various nanotopographies that are now being used in scaffold formation, by describing how they are made, and how these nanotopographies affect the immune system and potential underlying mechanisms. The advantages of 4D bioprinting in BTE by using nanoink have also been mentioned. Additionally, we have investigated the importance of an in silico approach for finding the interaction between drugs and their related receptors, which can help to formulate suitable systems for delivery. This review emphasizes the role of nanoscale approach and how it helps to increase the efficacy of parameters of scaffold as well as drug delivery system for tissue engineering and bone regeneration.

Influence of gelatin type on physicochemical properties of electrospun nanofibers

This study explores the fabrication of nanofibers using different types of gelatins, including bovine, porcine, and fish gelatins. The gelatins exhibited distinct molecular weights and apparent viscosity values, leading to different entanglement behavior and nanofiber production. The electrospinning technique produced nanofibers with diameters from 47 to 274 nm. The electrospinning process induced conformational changes, reducing the overall crystallinity of the gelatin samples. However, porcine gelatin nanofibers exhibited enhanced molecular ordering. These findings highlight the potential of different gelatin types to produce nanofibers with distinct physicochemical properties. Overall, this study sheds light on the relationship between gelatin properties, electrospinning process conditions, and the resulting nanofiber characteristics, providing insights for tailored applications in various fields.

Optimization of Oil Sorbent Thermoplastic Elastomer Microfiber Production by Centrifugal Spinning

Fibrous structures are promising candidates for oil-water separation applications. In this study, we have produced poly(styrene-b-isobutylene-b-styrene) thermoplastic elastomeric fibers with the centrifugal spinning fiber production method. The optimal fiber production conditions were achieved when using a 25% w/w solution concentration in an 80/20 tetrahydrofuran/toluene (w/w) solvent system at 8000 rpm rotational speed. The produced fibers were bead-free and smooth-surfaced with a diameter of 3.68 µm. The produced fibers were highly hydrophobic and oleophilic, suggested by a water contact angle of 129° and the instantaneous absorption of the oil droplet. The oil absorption study showed fast absorption kinetics with 94% relative oil uptake after 1 min and a maximum of 16.5 g sunflower oil/g fiber. The results suggest that polyisobutylene-based thermoplastic elastomers could be promising alternatives in oil absorption applications.