Development of a Multi-Layer Skin Substitute Using Human Hair Keratinic Extract-Based Hybrid 3D Printing

The Role of 3D Printing Technologies in Soft Grippers

Soft grippers are essential for precise and gentle handling of delicate, fragile, and easy-to-break objects, such as glassware, electronic components, food items, and biological samples, without causing any damage or deformation. This is especially important in industries such as healthcare, manufacturing, agriculture, food handling, and biomedical, where accuracy, safety, and preservation of the objects being handled are critical. This article reviews the use of 3D printing technologies in soft grippers, including those made of functional materials, nonfunctional materials, and those with sensors. 3D printing processes that can be used to fabricate each class of soft grippers are discussed. Available 3D printing technologies that are often used in soft grippers are primarily extrusion-based printing (fused deposition modeling and direct ink writing), jet-based printing (polymer jet), and immersion printing (stereolithography and digital light processing). The materials selected for fabricating soft grippers include thermoplastic polymers, UV-curable polymers, polymer gels, soft conductive composites, and hydrogels. It is conclude that 3D printing technologies revolutionize the way soft grippers are being fabricated, expanding their application domains and reducing the difficulties in customization, fabrication, and production.

Whey protein-loaded 3D-printed poly (lactic) acid scaffolds for wound dressing applications

Chronic skin wounds pose a global clinical challenge, necessitating effective treatment strategies. This study explores the potential of 3D printed Poly Lactic Acid (PLA) scaffolds, enhanced with Whey Protein Concentrate (WPC) at varying concentrations (25, 35, and 50% wt), for wound healing applications. PLA's biocompatibility, biodegradability, and thermal stability make it an ideal material for medical applications. The addition of WPC aims to mimic the skin's extracellular matrix and enhance the bioactivity of the PLA scaffolds. Fourier Transform Infrared Spectroscopy results confirmed the successful loading of WPC into the 3D printed PLA-based scaffolds. Scanning Electron Microscopy (SEM) images revealed no significant differences in pore size between PLA/WPC scaffolds and pure PLA scaffolds. Mechanical strength tests showed similar tensile strength between pure PLA and PLA with 50% WPC scaffolds. However, scaffolds with lower WPC concentrations displayed reduced tensile strength. Notably, all PLA/WPC scaffolds exhibited increased strain at break compared to pure PLA. Swelling capacity was highest in PLA with 25% WPC, approximately 130% higher than pure PLA. Scaffolds with higher WPC concentrations also showed increased swelling and degradation rates. Drug release was found to be prolonged with increasing WPC concentration. After seven days of incubation, cell viability significantly increased in PLA with 50% WPC scaffolds compared to pure PLA scaffolds. This innovative approach could pave the way for personalized wound care strategies, offering tailored treatments and targeted drug delivery. However, further studies are needed to optimize the properties of these scaffolds and validate their effectiveness in clinical settings.

Investigation of human hair keratin-based nanofibrous scaffold for skin tissue engineering application

Keratin-based nanofibers were fabricated using the electrospinning technique, and their potential as scaffolds for tissue engineering was investigated. Keratin, extracted from the human hair, was blended with poly(vinyl alcohol) (PVA) in an aqueous medium. Morphological characterizations of the fabricated PVA-keratin nanofiber (PK-NF) random and aligned scaffolds performed using a scanning electron microscope (SEM) revealed the formation of uniform and randomly oriented nanofibers with an interconnected three-dimensional network structure. The mean diameter of the nanofibers ranged from 100 to 250 nm. Functional groups and structural studies were done by infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. FTIR study suggested that PVA interacted with keratin by hydrogen bonding. Moreover, the in vitro cell culture study could suggest that PK-NF scaffolds were non-cytotoxic by supporting the growth of murine embryonic stem cells (ESCs), human keratinocytes (HaCaT), and dermal fibroblast (NHDF) cell lines. Further, the immunocytochemical characterization revealed the successful infiltration, adhesion, and growth of ESCs, HaCaT, and NHDF cells seeded on PK-NF scaffolds. However, there was no noteworthy difference observed concerning cell growth and viability irrespective of the random and aligned internal fibril arrangement of the PK-NF scaffolds. The infiltration and growth pattern of HaCaT and NHDF cells adjacent to each other in a 3D co-culture study mimicked that of epidermal and dermal skin cells and indeed underscored the potential of PK-NFs as a scaffold for skin tissue engineering.

Optimization Method to Predict Optimal Noise Reduction Parameters for the Non-Local Means Algorithm Based on the Scintillator Thickness in Radiography

The resulting image obtained from an X-ray imaging system depends significantly on the characteristics of the detector. In particular, when an X-ray image is acquired by thinning the detector, a relatively large amount of noise inevitably occurs. In addition, when a thick detector is used to reduce noise in X-ray images, blurring increases and the ability to distinguish target areas deteriorates. In this study, we aimed to derive the optimal X-ray image quality by deriving the optimal noise reduction parameters based on the non-local means (NLM) algorithm. The detectors used were of two thicknesses (96 and 140 μm), and images were acquired based on the IEC 62220-1-1:2015 RQA-5 protocol. The optimal parameters were derived by calculating the edge preservation index and signal-to-noise ratio according to the sigma value of the NLM algorithm. As a result, a sigma value of the optimized NLM algorithm (0.01) was derived, and this algorithm was applied to a relatively thin X-ray detector system to obtain appropriate noise level and spatial resolution data. The no-reference-based blind/referenceless image spatial quality evaluator value, which analyzes the overall image quality, was best when using the proposed method. In conclusion, we propose an optimized NLM algorithm based on a new method that can overcome the noise amplification problem in thin X-ray detector systems and is expected to be applied in various photon imaging fields in the future.

3D printed drug loaded nanomaterials for wound healing applications

Wounds are a stern healthcare concern in the growth of chronic disease conditions as they can increase healthcare costs and complicate internal and external health. Advancements in the current and newer management systems for wound healing should be in place to counter the health burden of wounds. Researchers discovered that two-dimensional (2D) media lacks appropriate real-life detection of cellular matter as these have highly complicated and diverse structures, compositions, and interactions. Hence, innovation towards three-dimensional (3D) media is called to conquer the high-level assessment and characterization in vivo using new technologies. The application of modern wound dressings prepared from a degenerated natural tissue, biodegradable biopolymer, synthetic polymer, or a composite of these materials in wound healing is currently an area of innovation in tissue regeneration medicine. Moreover, the integration of 3D printing and nanomaterial science is a promising approach with the potential for individualized, flexible, and precise technology for wound care approaches. This review encompasses the outcomes of various investigations on recent advances in 3D-printed drug-loaded natural, synthetic, and composite nanomaterials for wound healing. The challenges associated with their fabrication, clinical application progress, and future perspectives are also addressed.

Nano drug delivery systems: a promising approach to scar prevention and treatment

Scar formation is a common physiological process that occurs after injury, but in some cases, pathological scars can develop, leading to serious physiological and psychological effects. Unfortunately, there are currently no effective means to intervene in scar formation, and the structural features of scars and their unclear mechanisms make prevention and treatment even more challenging. However, the emergence of nanotechnology in drug delivery systems offers a promising avenue for the prevention and treatment of scars. Nanomaterials possess unique properties that make them well suited for addressing issues related to transdermal drug delivery, drug solubility, and controlled release. Herein, we summarize the recent progress made in the use of nanotechnology for the prevention and treatment of scars. We examine the mechanisms involved and the advantages offered by various types of nanomaterials. We also highlight the outstanding challenges and questions that need to be addressed to maximize the potential of nanotechnology in scar intervention. Overall, with further development, nanotechnology could significantly improve the prevention and treatment of pathological scars, providing a brighter outlook for those affected by this condition.

Integration of 3D Printing-Coelectrospinning: Concept Shifting in Biomedical Applications

Porous structures with sizes between the submicrometer and nanometer scales can be produced using efficient and adaptable electrospinning technology. However, to approximate desirable structures, the construction lacks mechanical sophistication and conformance and requires three-dimensional solitary or multifunctional structures. The diversity of high-performance polymers and blends has enabled the creation of several porous structural conformations for applications in advanced materials science, particularly in biomedicine. Two promising technologies can be combined, such as electrospinning with 3D printing or additive manufacturing, thereby providing a straightforward yet flexible technique for digitally controlled shape-morphing fabrication. The hierarchical integration of configurations is used to imprint complex shapes and patterns onto mesostructured, stimulus-responsive electrospun fabrics. This technique controls the internal stresses caused by the swelling/contraction mismatch in the in-plane and interlayer regions, which, in turn, controls the morphological characteristics of the electrospun membranes. Major innovations in 3D printing, along with additive manufacturing, have led to the production of materials and scaffold systems for tactile and wearable sensors, filtration structures, sensors for structural health monitoring, tissue engineering, biomedical scaffolds, and optical patterning. This review discusses the synergy between 3D printing and electrospinning as a constituent of specific microfabrication methods for quick structural prototypes that are expected to advance into next-generation constructs. Furthermore, individual techniques, their process parameters, and how the fabricated novel structures are applied holistically in the biomedical field have never been discussed in the literature. In summary, this review offers novel insights into the use of electrospinning and 3D printing as well as their integration for cutting-edge applications in the biomedical field.

Current Status and Future Outlook of Additive Manufacturing Technologies for the Reconstruction of the Trachea

Tracheal stenosis and defects occur congenitally and in patients who have undergone tracheal intubation and tracheostomy due to long-term intensive care. Such issues may also be observed during tracheal removal during malignant head and neck tumor resection. However, to date, no treatment method has been identified that can simultaneously restore the appearance of the tracheal skeleton while maintaining respiratory function in patients with tracheal defects. Therefore, there is an urgent need to develop a method that can maintain tracheal function while simultaneously reconstructing the skeletal structure of the trachea. Under such circumstances, the advent of additive manufacturing technology that can create customized structures using patient medical image data provides new possibilities for tracheal reconstruction surgery. In this study, the three-dimensional (3D) printing and bioprinting technologies used in tracheal reconstruction are summarized, and various research results related to the reconstruction of mucous membranes, cartilage, blood vessels, and muscle tissue, which are tissues required for tracheal reconstruction, are classified. The prospects for 3D-printed tracheas in clinical studies are also described. This review serves as a guide for the development of artificial tracheas and clinical trials using 3D printing and bioprinting.

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.

Biomaterials as a Vital Frontier for Stem Cell-Based Tissue Regeneration

Biomaterials and tissue regeneration represent two fields of intense research and rapid advancement. Their combination allowed the utilization of the different characteristics of biomaterials to enhance the expansion of stem cells or their differentiation into various lineages. Furthermore, the use of biomaterials in tissue regeneration would help in the creation of larger tissue constructs that can allow for significant clinical application. Several studies investigated the role of one or more biomaterial on stem cell characteristics or their differentiation potential into a certain target. In order to achieve real advancement in the field of stem cell-based tissue regeneration, a careful analysis of the currently published information is critically needed. This review describes the fundamental description of biomaterials as well as their classification according to their source, bioactivity and different biological effects. The effect of different biomaterials on stem cell expansion and differentiation into the primarily studied lineages was further discussed. In conclusion, biomaterials should be considered as an essential component of stem cell differentiation strategies. An intense investigation is still required. Establishing a consortium of stem cell biologists and biomaterial developers would help in a systematic development of this field.

A Minireview of Microfluidic Scaffold Materials in Tissue Engineering

In 2020, nearly 107,000 people in the U.S needed a lifesaving organ transplant, but due to a limited number of donors, only ∼35% of them have actually received it. Thus, successful bio-manufacturing of artificial tissues and organs is central to satisfying the ever-growing demand for transplants. However, despite decades of tremendous investments in regenerative medicine research and development conventional scaffold technologies have failed to yield viable tissues and organs. Luckily, microfluidic scaffolds hold the promise of overcoming the major challenges associated with generating complex 3D cultures: 1) cell death due to poor metabolite distribution/clearing of waste in thick cultures; 2) sacrificial analysis due to inability to sample the culture non-invasively; 3) product variability due to lack of control over the cell action post-seeding, and 4) adoption barriers associated with having to learn a different culturing protocol for each new product. Namely, their active pore networks provide the ability to perform automated fluid and cell manipulations (e.g., seeding, feeding, probing, clearing waste, delivering drugs, etc.) at targeted locations in-situ. However, challenges remain in developing a biomaterial that would have the appropriate characteristics for such scaffolds. Specifically, it should ideally be: 1) biocompatible-to support cell attachment and growth, 2) biodegradable-to give way to newly formed tissue, 3) flexible-to create microfluidic valves, 4) photo-crosslinkable-to manufacture using light-based 3D printing and 5) transparent-for optical microscopy validation. To that end, this minireview summarizes the latest progress of the biomaterial design, and of the corresponding fabrication method development, for making the microfluidic scaffolds.

Electrospinning and Additive Manufacturing: Adding Three-Dimensionality to Electrospun Scaffolds for Tissue Engineering

The final biochemical and mechanical performance of an implant or scaffold are defined by its structure, as well as the raw materials and processing conditions used during its fabrication. Electrospinning and Additive Manufacturing (AM) are two contrasting processing technologies that have gained popularity amongst the fields of medical research i.e., tissue engineering, implant design, drug delivery. Electrospinning technology is favored for its ability to produce micro- to nanometer fibers from polymer solutions and melts, of which, the dimensions, alignment, porosity, and chemical composition are easily manipulatable to the desired application. AM, on the other hand, offers unrivalled levels of geometrical freedom, allowing highly complex components (i.e., patient-specific) to be built inexpensively within 24 hours. Hence, adopting both technologies together appears to be a progressive step in pursuit of scaffolds that better match the natural architecture of human tissues. Here, we present recent insights into the advances on hybrid scaffolds produced by combining electrospinning (melt electrospinning excluded) and AM, specifically multi-layered architectures consisting of alternating fibers and AM elements, and bioinks reinforced with fibers prior to AM. We discuss how cellular behavior (attachment, migration, and differentiation) is influenced by the co-existence of these micro- and nano-features.

Recent Advances in Functional Polymer Materials for Energy, Water, and Biomedical Applications: A Review

Academic research regarding polymeric materials has been of great interest. Likewise, polymer industries are considered as the most familiar petrochemical industries. Despite the valuable and continuous advancements in various polymeric material technologies over the last century, many varieties and advances related to the field of polymer science and engineering still promise a great potential for exciting new applications. Research, development, and industrial support have been the key factors behind the great progress in the field of polymer applications. This work provides insight into the recent energy applications of polymers, including energy storage and production. The study of polymeric materials in the field of enhanced oil recovery and water treatment technologies will be presented and evaluated. In addition, in this review, we wish to emphasize the great importance of various functional polymers as effective adsorbents of organic pollutants from industrial wastewater. Furthermore, recent advances in biomedical applications are reviewed and discussed.