Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. To fit functional demand, materials with desired physical, chemical, biological, biomechanical, and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.

Biomedical applications of biodegradable polymers

There is a specialized niche for the electrohydrodynamic jetting of melts, from biomedical products to filtration and soft matter applications. The next frontier includes optics, microfluidics, flexible electronic devices, and soft network composites in biomaterial science and soft robotics. The recent emphasis on reproducibly direct-writing continual molten jets has enabled a spectrum of contemporary microscale 3D objects to be fabricated. One strong suit of melt processing is the capacity for the jet to solidify rapidly into a fiber, thus fixing a particular structure into position. The ability to direct-write complex and multiscaled architectures and structures has greatly contributed to a large number of recent studies, explicitly, toward fiber–hydrogel composites and fugitive inks, and has expanded into several biomedical applications such as cartilage, skin, periosteum, and cardiovascular tissue engineering. Following the footsteps of a publication that summarized melt electrowriting literature up to 2015, the most recent literature from then until now is reviewed to provide a continuous and comprehensive timeline that demonstrates the latest advances as well as new perspectives for this emerging technology.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adfm.201904664

The Next Frontier in Melt Electrospinning: Taming the Jet

Yarns are key building blocks to construct complicated fibrous structures for diverse applications. Although carbon nanotube yarns have been fabricated by a few novel techniques, challenges still remain in processing other nano fibrous materials into yarns, especially during the fiber fabricating process. In this paper, we report a simple but efficient and versatile method to prepare well‐twisted continuous nanofiber yarns directly through an electrospinning process. The yarn electrospinning process used two oppositely charged electrospinning nozzles to generate a hollow nanofiber “cone” on an intermediate funnel collector. Continuous nanofiber yarns can be directly withdrawn from the “cone” apex, with up to 7400 turns per meter of twists inserted through the rotation of the funnel. The maximum yarn production rate is 5 m/min, and the yarn twist level and fiber orientation can be controlled by the funnel rotating speed and yarn withdrawal rate. The yarn tensile properties showed dependence on the twist level.

Direct electrospinning of highly twisted, continuous nanofiber yarns

Corneal blindness is one of the most common causes of vision loss worldwide, affecting millions of people. To treat these patients, researchers have been examining different approaches to engineer corneal scaffolds suitable for transplantation. Scaffolds have been developed to replace part or all of the cornea depending on the patient requirements. Both acellular and cell-seeded scaffolds have been tested in animal models. Materials that have been under investigation for manufacturing scaffolds include collagen, silk fibroin, amniotic membrane, decellularized cornea, fibrin, chitosan, gelatin, agarose, alginate, and hyaluronic acid in addition to several synthetic polymers. Different combinations of materials, fiber crosslinking techniques, and incorporation of bioactive molecules have also been examined. Factors such as the physical properties, cytocompatibility, degradation behavior, and optical characteristics have to be considered when selecting a suitable scaffold material. Recent advancements in materials fabrication techniques such as bioprinting, electrospinning, and different collagen alignment techniques, allow scaffolds to be generated that more accurately mimic the structure of the corneal stroma. A number of scaffolds have commenced clinical trials to determine their suitability for corneal regeneration.

/pdf/designing-scaffolds-for-corneal-regeneration-5c6fu67skz.pdf

Designing Scaffolds for Corneal Regeneration

https://doi.org/10.1016/j.apmt.2022.101473

State-of-the-art review of advanced electrospun nanofiber yarn-based textiles for biomedical applications

Background: Corneal endothelial dysfunction remains the most frequent indication for corneal transplantation, limited by donor material shortage, poor long-term graft survival, or allogeneic graft ...

Electro-spun Membranes as Scaffolds for Human Corneal Endothelial Cells.

Electro-spinning is widely used in tissue-engineered applications mostly in form of non-woven structures. The development of e-spun yarn opens the door for textile fabrics which combine the micro to nanoscale dimension of electro-spun filaments with three-dimensional (3D) drapable textile fabrics. Therefore, the aim of the study was the implementation of a process for electro-spun yarns. Polylactic acid (PLA) and polyethylene glycol (PEG) were spun from chloroform solutions with varying PLA/PEG ratios (100:0, 90:10, 75:25 and 50:50). The yarn samples produced were analyzed regarding their morphology, tensile strength, water uptake and cytocompatibility. It was found that the yarn diameter decreased when the funnel collector rotation was increasd, however, the fiber diameter was not influenced. The tensile strength was also found to be dependent on the PEG content. While samples composed of 100% PLA showed a tensile strength of 2.5±0.7 cN/tex, the tensile strength increased with a decreasing PLA content (PLA 75%/PEG 25%) to 6.2±0.5 cN/tex. The variation of the PEG content also influenced the viscosity of the spinning solutions. The investigation of the cytocompatibility with endothelial cells was conducted for PLA/PEG 90:10 and 75:25 and indicated that the samples are cytocompatible.

Electro-spun PLA-PEG-yarns for tissue engineering applications.

This paper describes a magnetic nanotechnology that locally enables hyperthermia treatment of hollow organ tumors by using polymer hybrid stents with incorporated magnetic nanoparticles (MNP). The hybrid stents are implanted and activated in an alternating magnetic field to generate therapeutically effective heat, thereby destroying the tumor. Here, we demonstrate the feasibility of nanomagnetic actuation of three prototype hybrid stents for hyperthermia treatment of hollow organ tumors. The results show that the heating efficiency of stent filaments increases with frequency from approximately 60 W/gFe (95 kHz) to approximately 250 W/gFe (270 kHz). The same trend is observed for the variation of magnetic field amplitude; however, heating efficiency saturates at approximately 30 kA/m. MNP immobilization strongly influences heating efficiency showing a relative difference in heating output of up to 60% compared to that of freely dispersed MNP. The stents showed uniformly distributed heat on their surface reaching therapeutically effective temperatures of 43 °C and were tested in an explanted pig bile duct for their biological safety. Nanomagnetic actuation of hybrid stents opens new possibilities in cancer treatment of hollow organ tumors.

Nanomagnetic Actuation of Hybrid Stents for Hyperthermia Treatment of Hollow Organ Tumors

Assessing hyperthermia performance of hybrid textile filaments: The impact of different heating agents

A facile route was proposed to fabricate core–sheath microfibers, and the relationships among processing parameters, crystalline structures and the mechanical properties were investigated. The comp...

Benedict Bauer

Papers

Electro-spun Membranes as Scaffolds for Human Corneal Endothelial Cells.

Electro-spun PLA-PEG-yarns for tissue engineering applications.

Nanomagnetic Actuation of Hybrid Stents for Hyperthermia Treatment of Hollow Organ Tumors

Assessing hyperthermia performance of hybrid textile filaments: The impact of different heating agents

Structure and properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/poly(L-lactic acid) quasi core/sheath melt-electrospun microfibers: