Increase In Fiber Diameter Research Articles

Coralline Halimeda opuntia algae-derived bio-hydroxyapatite enhances the bioactivity of piezoelectric tissue engineering scaffolds

Biomaterials are increasingly being used to promote tissue repair after wounds. Coralline algae have been reported as valuable sources of hydroxyapatite (HAp). The identification and characterization of Halimeda opuntia with high calcium carbonate content from the Indian Ocean have been performed. Bio-hydroxyapatite (Bio-HAp) was synthesized through a combined process of pyrolysis followed by a hydrothermal treatment. The effect of pyrolysis temperature on the critical properties of the HAp such as Ca/P ratio, morphology and presence of trace elements was assessed. It was found that a calcination temperature of 900 °C produced Bio-HAp with a Ca/P of 1.57 ± 0.01, which is non-stoichiometric and calcium-deficient, similar to the HAp integrated in bone. HAp can integrate with bone without causing any local or systemic toxicity, inflammation or foreign body response, thus we have loaded the synthesized Bio-HAp into piezoelectric PHBV/PDX electrospun mat and assessed the behaviour of human dermal fibroblasts (HDF) and human pre-osteoblasts (HoB) in co-culture at different cell densities. Increasing Bio-HAp content from 1 % to 5 % increased fiber diameter due to fiber melting. Bio-HAp enhanced differentiation of HDF promoting mineralisation with Ca/P ratios of 1.93 ± 0.17 and 1.80 ± 0.18 at 1 % and 5 % HAp content respectively. The mineralisation process was more prominent on scaffolds with Bio-HAp compared to the controls (0 % HAp and synthetic-HAp) with both HDF only and HDF/HoB.

In situ creation of aramid fiber surface coating with polymerizable deep eutectic solvents and their interfacial bonding properties with rubber

AbstractThe coating was created on the surface of aramid fibers (AFs) by solution dip‐coating and in situ UV curable method, using a polymerizable deep eutectic solvent (PDES), dissolved poly(ethylene imine), and poly(ethylene glycol) diacrylate (PEGDA). Fourier transform infrared spectroscopy and thermogravimetry confirmed the successful construction of the coating on the AF surface, which accounted for 12%–17% of the total fiber mass. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images revealed a 2 μm increase in fiber diameter and a maximum fiber surface average roughness (Ra) of 263.7 nm when the polyethyleneimine content was 0.5% (AF‐PDES‐0.5). Based on these results, H pull‐out samples of fiber/rubber composites were fabricated. The results indicated that the H pull‐out force of AF‐PDES‐0.5 samples increased by 109.74% than that of untreated fiber, and reached 12.92 N of the maximum strength. In summary, the method is simple, rapid, non‐polluting, capable of continuous, and intelligent construction of coatings on the surface of AF. Thus, making it highly promising for application in the field of aviation tires.Highlights Using PDES, green, and low‐carbon preparation processes. Solution dip‐coating and UV reaction for improved reaction speed and workability. Quantitative of interface thickness and modulus using EDS and AFM.

Application of artificial intelligence in predicting the residual mechanical properties of fiber reinforced concrete (FRC) after high temperatures

The practical application of Artificial Intelligence (AI) approaches in estimating the mechanical properties of fiber-reinforced concrete (FRC) subjected to high temperatures was initiated by developing a dataset including concrete mixtures, geometrical and mechanical properties of fiber, and temperatures. The dataset contains compressive strength, tensile strength, and modulus of elasticity of concrete with two distinct types of fiber, i.e., steel and polypropylene with an extensive range of temperatures from 100 to 1200 ℃. The dataset determined the gaps in the literature and showed FRC with high fiber aspect ratios and higher content of fiber (>0.8%) are not studied enough. The AI-based models showed that steel fiber-reinforced concrete (SFRC) has higher residual compressive strength compared with polypropylene fiber-reinforced concrete (PFRC). An increase in steel fiber diameter and length resulted in a higher compressive strength ratio at all temperatures. Moreover, higher PP fibers content and longer PP fibers decrease the rate of tensile strength degradation. A large probabilistic analysis was performed, and it showed that the failure probability (Pf) for PFRC is independent of W/B ratios and is almost 50%;. In contrast, for SFRC, W/B ratios between 0.4 to 0.5 have lower failure probability in comparison with other W/B ratios. Moreover, Pf for both fibers at a W/B ratio of 0.5 is almost independent of fiber content. Furthermore, the critical temperature resulting in failure (defined as the residual strength ratio less than 0.5) for SFRC and PFRC is 550 ℃ and 430 ℃, respectively.

Development of myofibers and muscle transcriptomic analysis in growing Yili geese

In poultries, muscle growth is a quantitative trait controlled by multiple genes. The regulatory mechanisms governing muscle tissue growth and development in poultry, particularly during the early stages of growth, are intricate. Through the examination of leg muscle transcripts from Yili geese during various stages of development, this study offers valuable insights into the molecular mechanisms underlying the growth and development of Yili geese. This study aimed to perform a comparative analysis of the histological characteristics of leg muscles and the mRNA expression profiles of leg muscles in Yili geese at different ages (2, 4, 6, 8, and 10 wk). The objective was to identify differentially expressed genes related to muscle development in Yili geese and utilize bioinformatics to predict the potential biological functions of these genes. Through histological studies on leg muscle tissues, it was discerned that male geese at 4 wk exhibit a significantly reduced muscle fiber density in comparison to females (P < 0.01). In contrast, by the time they reach 6, 8, and 10 wk, their muscle fiber diameter and cross-sectional dimensions significantly outpace the females (P < 0.01). With the advancement in age, muscle fiber density tends to decrease. It is worth noting that 4- and 6-wk-old male geese have a substantially elevated muscle fiber density when matched against females (P < 0.01). Conversely, at the age of 10 wk, their muscle fiber density is notably inferior to the females (P < 0.01). Furthermore, male geese exhibit the most rapid increase in muscle fiber diameter and cross-sectional area between 4 and 6 wk of age. The density of muscle fibers in these geese significantly decreases from 4 to 8 wk. In contrast, female geese show the most pronounced growth in muscle fiber diameter and cross-sectional area between 2 and 6 wk, with a swift decline in density following the 6-wk mark, accompanied by a gradual reduction in the rate of muscle fiber growth. A comprehensive analysis of the leg muscle mRNA expression profiles from 12 Yili geese generated a cumulative total of 502,065,268 valid sequence reads, corresponding to a data volume of 75.30 Gb. In a comparative analysis between 4-wk-old and 2-wk-old groups (T4 vs. T2), 8-wk-old and 2-wk-old groups (T8 vs. T2), and 8-wk-old and 4-wk-old groups (T8 vs. T4), we identified 1,700, 1,583, and 221 differentially expressed genes (DEGs), respectively. Differentially expressed genes were significantly enriched in Gene Ontology (GO) terms such as organelle organization, cytoskeletal protein binding, cation transport, myosin complex, and actin cytoskeleton. Among the significantly enriched signaling pathways, 5 pathways were found to be significantly related to growth and development: adhesion patch, extracellular matrix receptor interaction, tight junction, TGF-β signaling pathway, and MAPK signaling pathway, with a total of 38 differentially differentiated genes contained in these 5 pathways, and it was hypothesized that the above pathways as well as the DEGs in the pathways played an important role in the regulation of early growth and development of the Yili goose. This investigation serves as a foundational reference for elucidating the molecular regulatory mechanisms involved in the development of goose muscle. Furthermore, it contributes to the expansion of the theoretical framework concerning the genetic regulation of muscle growth in geese.

An analysis of the wool characteristics that determine wool price for Merino wool in South Africa

Globally, wool characteristics determine wool price. As a result, wool that does not match the standards for fibre diameter, clean yield and staple length at auctions are sold at cheaper prices. At global level, very few studies in the literature of wool characteristics that determine wool price have attempted to evaluate the actual percentage of clean yield that is required at a wool auction. The actual percentage of clean yield that is required at the wool auction for Merino wool is important to consider for methods that can be applied to improve clean yield. The objective of this study was to investigate the effect of wool characteristics (fibre diameter, clean yield and staple length) on the determination of Merino wool price in South Africa. The data of wool prices from 2009 to 2019 wool seasons was used for analysis. A multiple regression analysis of price (Rand/kg) of Merino wool was applied to three variables (fibre diameter, clean yield and staple length). Taken each variable separately, fibre diameter, clean yield and staple length made a statistically significant (p < 0.05) contribution to the determination of wool price, after controlling all other independent variables. Considering each variable separately, a one unit (µ) increase in fibre diameter was associated with a 30.236 unit decrease in wool price (Rand/kg). A one decimal unit increase in clean yield (%) was associated with 1.353 unit increase in wool price (Rand/kg). A one unit (mm) increase in staple length was associated with 0.912 unit increase in wool price (Rand/kg). The results indicated that clean yield is a challenge for Merino wool farmers. It is important that the Merino sheep breeds are shorn first at the shearing sheds to avoid contamination of wool with coloured fibres, kemp or crossbreed wool.

Porcine Acellular Nerve-Derived Hydrogel Improves Outcomes of Direct Muscle Neurotization in Rats.

Background: The ability to reinnervate a muscle in the absence of a viable nerve stump is a challenging clinical scenario. Direct muscle neurotization (DMN) is an approach to overcome this obstacle; however, success depends on the formation of new muscle endplates, a process, which is often limited due to lack of appropriate axonal pathfinding cues. Objective: This study explored the use of a porcine nerve extracellular matrix hydrogel as a neuroinductive interface between nerve and muscle in a rat DMN model. The goal of the study was to establish whether such hydrogel can be used to improve neuromuscular function in this model. Materials and Methods: A common peroneal nerve-to-gastrocnemius model of DMN was developed. Animals were survived for 2 or 8 weeks following DMN with or without the addition of the hydrogel at the site of neurotization. Longitudinal postural thrust, terminal electrophysiology, and muscle weight assessments were performed to qualify and quantify neuromuscular function. Histological assessments were made to qualify the host response at the DMN site, and to quantify neuromuscular junctions (NMJs) and muscle fiber diameter. Results: The hydrogel-treated group showed a 132% increase in postural thrust at 8 weeks compared with that of the DMN alone group. This was accompanied by an 80% increase in the number of NMJs at 2 weeks, and 26% increase in mean muscle fiber diameter at 8 weeks. Conclusions: These results suggest that a nerve-derived hydrogel may improve the neuromuscular outcome following DNM.

Computational homogenization of linear elastic properties in porous non-woven fibrous materials

Porous non-woven fibrous media are widely used in various industrial applications such as filtration, insulation, and medical textiles due to their unique structural and functional properties. However, predicting the mechanical behavior of these materials is challenging due to their complex microstructure and anisotropic nature. In this study, a computational model is developed to simulate the mechanical response of porous non-woven fibrous media under external loading. The model is based on the finite element method and takes into account the geometric and material properties of the fibers and the void spaces between them. The effects of various factors such as fiber size, porosity, and fibers’ intersection ratio on the mechanical behavior of the material are investigated. The results reveal that the material’s porosity and fibers’ intersection ratio are the most significant factors influencing its mechanical properties. Additionally, the increase in fiber diameter has a relatively minor effect on the material’s elastic properties. However, such changes in elastic properties are primarily attributed to the increase in randomness within the fibrous network, which is directly related to the fiber diameter for the investigated structure. The proposed computational model predicts the mechanical properties of porous non-woven fibrous media and can provide invaluable insights into the design and optimization of porous non-woven fibrous media for various scientific and engineering applications.

Paper sludge saccharification for batch and fed-batch production of bacterial cellulose decorated with magnetite for dye decolorization by experimental design

Cellulosic wastes represent a great environmental challenge, with potential conversion to product-added value through microbial fermentation. Currently, bacterial cellulose (BC) is considered a promising natural polymer for multiple applications. However, the high production cost challenges its wide application. Hence, the current study evaluated the applicability of paper sludge as a cost-effective medium for both cellulases and BC production. The local isolate Streptomyces rochei revealed the highest cellulase production titer (about 3 U/mL) at optimized conditions. For BC production, batch and fed-batch fermentation strategies were evaluated using enzymatically hydrolyzed paper sludge. The results asserted the advantage of fed-batch fermentation for advanced BC production (3.10 g/L) over batch fermentation (1.06 g/L) under the same cultivation conditions. The developed BC membranes were characterized through different instrumental analyses, which revealed an increase in fiber diameters and crystallinity under fed-batch fermentation. Furthermore, BC/magnetite (BC/Fe3O4) nanocomposite was developed by an in-situ approach. The newly developed composite was evaluated for dye removal applications, using methyl orange (MO) as a model. The dye removal conditions were optimized through Box Behnken design (BBD), which indicated maximal MO removal (83.5%) at pH 3.0 and BC/Fe3O4 concentration of 0.1 mg/dL after 60 min. Therefore, the current study asserts the good applicability of enzymatically hydrolyzed paper sludge as a medium for cost-effective BC production and the high capacity of BC/magnetite nanocomposite for MO decolorization. The study paves the way for the cost-effective implementation of BC/magnetite nanocomposite for dye removal.Graphical

An analysis of the wool characteristics that determine wool price in South Africa

Purpose South Africa’s wool industry plays an important role in the agricultural sector. The wool industry provides a valuable source of income for farmers who practice sustainable farming practices. However, wool farmers face numerous challenges, such as wool contamination, dirty wool and producing good-quality wool. Good-quality wool is determined by fibre diameter, clean yield, vegetable matter and staple length. This study aims to address these challenges. Design/methodology/approach A multiple regression analysis of price (R/kg) of White wool and Merino wool was applied to four variables fibre diameter: vegetable matter, clean yield and staple length. The analysis was based on the data for the 2009–2019 data from Cape Wools auctions. Findings Fibre diameter, clean yield and staple length, with exception of vegetable matter, made a statistically significant contribution to the determination of wool price after all other independent variables were controlled for (p &lt; 0.05). A one-unit (micron) increase in fibre diameter resulted in a 0.404-unit decrease in wool price (R/kg). A one-unit (mm) increase in staple length resulted in a 0.022-unit increase in wool price (R/kg). There was no statistically significant association between vegetable matter and wool price. A one-unit increase in clean yield was associated with a 0.111-unit increase in wool price (R/kg). Research limitations/implications Since wool fleeces consist of the largest portion of wool shorn from sheep, it is important for wool farmers to focus on wool with low fibre diameter, high clean yield percentage, low percentage of vegetable matter content and good length of the wool. Practical implications Since wool fleeces consist of the largest portion of wool shorn from sheep, it is important for wool farmers to focus on wool with low fibre diameter, high clean yield percentage, low percentage of vegetable matter content and good length of the wool. Social implications In a developing country such as South Africa, this study is important for the following reason. It is understanding the wool characteristics that have the most significance influence on the determination of wool price for Merino wool and White wool might effectively help the wool farmers to adapt their production systems to improve the wool characteristics that determine wool price. Originality/value This study identified a need for a study to be conducted on all wool classes.

Fabrication of nanoclay embedded adsorptive electrospun nanofiber membrane for removal of trace organic molecules

This study aims to fabricate nanoclay (NC) embedded polyacrylonitrile (PAN) adsorptive electrospun nanofibers (Ads-ESNs) as high performance membranes for organic micropollutants (OMPs) removal. Ads-ESN were tested using a comprehensive protocol included adsorption in batches (static) and during filtration (dynamic). The filtration performance of Ads-ESNs was tested using gravity driven membrane (GDM) filtration using methylene blue (MB) as an adsorbate of similar characteristics to OMPs. The characterization was carried using SEM-EDS, FTIR and BET N2 adsorption/desorption technique. Addition of NC increased fiber diameters from 164 to 355 nm and surface areas from 12.9 to 45.9 m2/g. Accordingly, Ads-ESNs had 7 times higher adsorption capacity than PAN-ESN with isotherms fitting to Langmuir model (R2 = 0.9511–0.9899). The kinetics showed that adsorption in Ads-ESNs followed pseudo 1st and 2nd order indicating the occurrence of physisorption and chemisorption mechanisms simultaneously. pH and temperature effect were investigated and the results showed that highest adsorption occurred at pH 7 and 25 °C. The GDM system was operated at constant permeate flow rates of 1.0, 2.0 and 4.0 mL/min at 50mbar. MB rejection was over 90% at 1.0 and 2.0 mL/min of flow rates indicating the effect of applying lower flow rate and higher contact time. The adsorption capacities of Ads-ESN were different at static and dynamic adsorption due to different equilibrium states achieved at both adsorption modes. The fabricated Ads-ESNs showed outstanding removal performance for trace organic molecules even after four adsorption+filtration/regeneration cycles. Overall, this study demonstrated the potentials of combining membrane filtration and adsorption in a single-step process at same entity.

Diameter-Dependent Shape Memory Effect and Superelasticity in Ni-Mn-Ga Alloy Micro-fibers

Abstract: The functional properties of shape memory alloys (SMAs) may be affected by the material size and thus is important for designing micron-sized devices. Here the diameter-dependent size effect was demonstrated in Ni-Mn-Ga fibers with diameters of 15, 41, 53 and 70μm. The effect of fiber diameter on the shape memory effect (SME) and superelasticity (SE) was systematically studied. The results showed that all Ni-Mn-Ga fibers exhibited good stress assisted thermal cycles and SE, both diameter-dependent. For stress assisted thermal cycles, the temperature hysteresis of martensite transformation (MT) and sensitivity of MT temperature vs stress increased with increasing fiber diameter. While for SE, the stress hysteresis, temperature dependence of critical stress and energy dissipation capacity decreased with increasing fiber diameter. Thermodynamic analysis revealed that the diameter-dependent effect may be attributed to the different heat exchange and frictional work dissipation capacities related to the specific surface areas that affected the thermal- or stress-induced MT processes. Such diameter dependence in Ni-Mn-Ga micro-fibers needs to be considered for the design and application in micro-sized devices.

Mesoscopic Simulation of Centrifugal Melt Electrospinning of PPESK

AbstractPoly(aryl ether sulfone ketone) (PPESK) is an engineering plastic with high strength, good heat resistance, insulation, and chemical corrosion resistance. The properties of PPESK fiber prepared by centrifugal melt electrospinning can be improved, and the method is efficient and environmentally friendly. This article employs a systematic analysis to investigate the impact of process parameters on the jet formation process, jet motion, fiber diameter, fiber yield, and changes in molecular chain orientation of PPESK. The analysis uses dissipative particle dynamics simulation to reveal that PPESK fibers can attain a certain degree of refinement, and fiber yield can be increased with an appropriate increase in rotational speed, temperature, and electric field force. Moreover, for PPESK with different chain lengths, longer molecular chains impede the untwisting of the molecular chains within the fiber, weakening the fiber orientation, increasing fiber diameter, and resulting in a slower fiber yield increase. These simulation results provide theoretical guidance for preparing PPESK ultrafine fibers with the required performance, shortening the exploration process of actual spinning, and saving time and labor.

Friction behavior of biodegradable electrospun polyester nanofibrous membranes

Tribological properties of implantable degradable polyester membranes are critical but little research has been dedicated to this. In this work, we prepared electrospun polylactic acid (PLA) membranes and enzyme-degraded PLA (ED-PLA) membranes. SEM images showed an increase in average fiber diameter and porosity after enzymatic degradation of PLA membranes, indicating that PLA was propriety degradation mode. Friction testing results showed that different test parameters resulted in different friction data, but ED-PLA sample seemed to wear faster than PLA sample under same test parameters. Besides, we also discussed the effective way to improve surface lubrication performance of electrospun polyester membranes. This research aims to realize the importance of surface tribological performance of implanted biomaterials and provide technical standards for friction tests.

Bilateral Functional Electrical Stimulation for the Treatment of Presbyphonia in a Sheep Model.

The aim of the study was to increase muscle volume and improve phonation characteristics of the aged ovine larynx by functional electrical stimulation (FES) using a minimally invasive surgical procedure. Stimulation electrodes were placed bilaterally near the terminal adduction branch of the recurrent laryngeal nerves (RLN). The electrodes were connected to battery powered pulse generators implanted subcutaneously at the neck region. Training patterns were programmed by an external programmer using a bidirectional radio frequency link. Training sessions were repeated automatically by the implant every other day for 1 week followed by every day for 8 weeks in the awake animal. Another group of animals were used as sham, with electrodes positioned but not connected to an implant. Outcome parameters included gene expression analysis, histological assessment of muscle fiber size, functional analysis, and volumetric measurements based on three-dimensional reconstructions of the entire thyroarytenoid muscle (TAM). Increase in minimal muscle fiber diameter and an improvement in vocal efficiency were observed following FES, compared with sham animals. This is the first study to demonstrate beneficial effects in the TAM of FES at molecular, histological, and functional levels. FES of the terminal branches of the RLN reversed the effects of age-related changes and improved vocal efficiency. NA Laryngoscope, 134:848-854, 2024.

AAV1.NT-3 gene therapy in the SOD1KO mouse model of accelerated sarcopenia.

Sarcopenia, an age-related loss of muscle mass, is a critical factor that affects the health of the older adults. The SOD1KO mouse is deficient of Cu/Zn superoxide dismutase, used as an accelerated aging model. We previously showed that NT-3 improves muscle fibre size by activating the mTOR pathway, suggesting a potential for attenuating age-related muscle loss. This study assessed the therapeutic efficacy of AAV1.NT-3 in this accelerated aging model. Twelve 6months old SOD1KO mice were injected intramuscularly with a 1×1011 vg dose of AAV1.tMCK.NT-3, and 13 age-matched SOD1KO mice were used as controls. The treatment effect was evaluated using treadmill, rotarod and gait analyses as well as histological studies assessing changes in muscle fibre, and fibre type switch, in tibialis anterior, gastrocnemius, and triceps muscles, and myelin thickness by calculating G ratio in sciatic and tibial nerves. Molecular studies involved qPCR experiments to analyse the expression levels of mitochondrial and glycolysis markers and western blot experiments to assess the activity of mTORC1 pathway. Treatment resulted in a 36% (154.9 vs. 114.1; P<0.0001) and 76% increase (154.3 vs. 87.6; P<0.0001) in meters ran, with treadmill test at 3 and 6months post gene delivery. In addition, the treated cohort stayed on rotarod 30% (52.7s vs. 40.4s; P=0.0095) and 54% (50.4s vs. 32.7s; P=0.0007) longer, compared with untreated counterparts at 3 and 6months post injection. Gait analysis, performed at endpoint, showed that stride width was normalized to wild type levels (29.3mm) by an 11% decrease, compared with untreated cohort (28.6mm vs. 32.1mm; P=0.0014). Compared with wild-type, SOD1KO mice showed 9.4% and 11.4% fibre size decrease in tibialis anterior and gastrocnemius muscles, respectively, which were normalized to wild type levels with treatment. Fibre diameter increase was observed prominently in FTG fibre type. G ratio analysis revealed hypomyelination in the tibial (0.721) and sciatic (0.676) nerves of SOD1KO model, which was reversed in the NT-3 cohort (0.646 and 0.634, respectively). Fibre size increase correlated with the increase in the p-S6 and p-4E-BP1 levels, and in the glycolysis markers in tibialis anterior. Alterations observed in the mitochondrial markers were not rescued with treatment. Overall, response to NT-3 was subdued in gastrocnemius muscle. This study shows that AAV1.NT-3 gene therapy protected SOD1KO mouse from accelerated aging effects functionally and histologically. We further confirmed that NT-3 has potential to activate the mTOR and glycolytic pathways in muscle.

Chondroitinase ABC Treatment Improves the Organization and Mechanics of 3D Bioprinted Meniscal Tissue.

The meniscus is a fibrocartilage tissue that is integral to the correct functioning of the knee joint. The tissue possesses a unique collagen fiber architecture that is integral to its biomechanical functionality. In particular, a network of circumferentially aligned collagen fibers function to bear the high tensile forces generated in the tissue during normal daily activities. The limited regenerative capacity of the meniscus has motivated increased interest in meniscus tissue engineering; however, the in vitro generation of structurally organized meniscal grafts with a collagen architecture mimetic of the native meniscus remains a significant challenge. Here we used melt electrowriting (MEW) to produce scaffolds with defined pore architectures to impose physical boundaries upon cell growth and extracellular matrix production. This enabled the bioprinting of anisotropic tissues with collagen fibers preferentially oriented parallel to the long axis of the scaffold pores. Furthermore, temporally removing glycosaminoglycans (sGAGs) during the early stages of in vitro tissue development using chondroitinase ABC (cABC) was found to positively impact collagen network maturation. Specially we found that temporal depletion of sGAGs is associated with an increase in collagen fiber diameter without any detrimental effect on the development of a meniscal tissue phenotype or subsequent extracellular matrix production. Moreover, temporal cABC treatment supported the development of engineered tissues with superior tensile mechanical properties compared to empty MEW scaffolds. These findings demonstrate the benefit of temporal enzymatic treatments when engineering structurally anisotropic tissues using emerging biofabrication technologies such as MEW and inkjet bioprinting.

Design and manufacture of an additive manufacturing printer based on 3D melt electrospinning writing of polymer

Abstract Objectives Electrospinning is one of the most well-known approaches to producing polymer nanofibers from a polymer solution by applying a potential difference (voltage) between the spinner and the collector, which is used in various industries such as medicine and military. This method has some significant restrictions, like low process efficiency due to the evaporation of the solvent, remaining solvent on the fibers, which are sometimes toxic, and inability to control the geometry of the produced fibers. On the other hand, preparing some solvents used in the electrospinning of polymer solutions is costly. Polymer melt electrospinning writing is a replacement for this type of electrospinning, which can be mentioned in terms of economy, efficiency, and production of solvent-free fibers. Therefore, in this research, a melt polymer electrospinning device was designed and manufactured according to existing extrusion-based additive manufacturing (AM) devices (3D printer). Methods Changes in an extrusion-based 3D printer to convert it into a writing electrospinning device experimentally. Results PLA and PCL fibers with diameters ranging from 8 to 84 μm were produced. The effect of process variables on the produced fibers’ diameter was investigated: Applied potential difference between the nozzle and the substrate: As its increases, the fiber diameter decreases. Increasing temperature: As its increases, the fiber diameter decreases. Distance between the nozzle and the substrate: As its increases, the fiber diameter increases. Flow rate: As its increases, the fiber diameter increases. Conclusions By presenting a 3D printer-electrospinning device, it is possible to control the fiber’s diameter and the 3D geometry in the 3D printing-electrospinning process.

Systemic vascular photobiomodulation accelerates the recovery of motor activity in rats following spinal cord injury.

Spinal cord injury (SCI) causes the discontinuity of the spinal canal, leading to functional and sensorial losses in areas below the injury, which are often irreversible. Photobiomodulation (PBM) can enhance the neuromuscular repair process, especially in cases of peripheral nerve injuries. However, there is little knowledge regarding the effects of this therapeutic modality on recovery following a SCI, especially the noninvasive systemic form denominated vascular PBM (VPBM). To analyze the effects of VPBM in the immediate, acute and intermediate phases following a compression-induced SCI on morphological aspects of neuromuscular tissue repair, functional recovery and the protein expression of brain-derived neurotrophic factor (BDNF). Wistar rats were divided into five groups: control, SCI, SCI + VPBM-Im (immediate administration of VPBM), SCI + VPBM-2h (VPBM administered 2 h after injury) and SCI + VPBM-14d (VPBM administered 14 days after injury). VPBM was administered in the region of the caudal vein/artery with low-level laser (AsGaAl, 780 nm, 80 J/cm², 40 mW for 80 s, totaling an energy of 3.2 J over a single point) for 14 consecutive days. During the analysis periods (1, 3, 7, 14, 21, 28 and 35 days after injury), functioning was evaluated using the Basso-Beattie-Bresnahan (BBB) index. At the end of each experimental period, blood samples were collected for the determination of the concentration of circulating BDNF using ELISA. Muscle tissue and nerve tissue samples were also extracted for morphological and histological analyses using H&E staining. SCI + VPBM-Im and SCI + VPBM-2 h led to the recovery of motor function beginning on the 7th day after injury (p < 0.05), an increase in the cross-sectional area (CSA) of the muscle fibers in the second week (p < 0.05) and an increase in muscle fiber diameter beginning on Day 14 (p < 0.05). Early irradiation had a greater effect on the reduction in the size of the cavity, with stabilization of the cavity found on Day 7 (p < 0.05). Considering the circulating BDNF levels, no changes was found during the experimental periods. The present results showed that VPBM was capable of modulating morphological and functional recovery following SCI, especially when administered early. The positive effects on functional recovery were demonstrated by the BBB index; the reestablishment of the structure of the muscle and nerve tissue was demonstrated by the preservation of CSA and diameter of muscle fiber and reduction in the area of the injury (cavity size) respectively. Thus, noninvasive VPBM may be an important component of treatment for spinal cord injuries.

Investigation of the antitumor effect on breast cancer cells of the electrospun amygdalin-loaded poly(l-lactic acid)/poly(ethylene glycol) nanofibers

In this study, PLA/PEG nanofibers (NFs) loaded with amygdalin (AMG) and bitter almond kernels extract were produced by electrospinning to prevent local breast cancer recurrence, and the effect of produced NFs on the MCF-7 cell line was investigated in vitro. The electrospun NFs were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), thermal analysis (DSC) and tensile strength and physical analyzes were performed. Loading of AMG to nanofibers increased fiber diameters from 827.93 ± 174.507 nm to 1855.32 ± 291.057 μm. When drug release results were analyzed, the NFs showed a controlled release profile extending up to 10 h. The encapsulation efficiency of AMG-loaded NFs was calculated at 100 ± 0,01 %, 94 ± 0,02 %, and 88 ± 0,02 %. When in vitro cytotoxicity results were analyzed, showed that all NFs are effective in inducing cytotoxicity against MCF-7 breast cancer cells. Importantly, 20 mg AMG-loaded NFs displayed effectively higher cytotoxic effects against breast cancer cells relative to the other NFs. Considering all the results, AMG-loaded NFs can give sustained release of drugs at the local sites. Therefore, AMG-loaded nanofibers can reduce the risk of local recurrence of cancer after surgery and can be directly implanted into solid tumor cells for treatment.

Bioactive cellulose acetate nanofiber loaded with annatto support skeletal muscle cell attachment and proliferation.

Electrospinning emerged as a promising technique to produce scaffolds for cultivated meat in function of its simplicity, versatility, cost-effectiveness, and scalability. Cellulose acetate (CA) is a biocompatible and low-cost material that support cell adhesion and proliferation. Here we investigated CA nanofibers, associated or not with a bioactive annatto extract (CA@A), a food-dye, as potential scaffolds for cultivated meat and muscle tissue engineering. The obtained CA nanofibers were evaluated concerning its physicochemical, morphological, mechanical and biological traits. UV-vis spectroscopy and contact angle measurements confirmed the annatto extract incorporation into the CA nanofibers and the surface wettability of both scaffolds, respectively. SEM images revealed that the scaffolds are porous, containing fibers with no specific alignment. Compared with the pure CA nanofibers, CA@A nanofibers showed increased fiber diameter (420 ± 212nm vs. 284 ± 130nm). Mechanical properties revealed that the annatto extract induces a reduction of the stiffness of the scaffold. Molecular analyses revealed that while CA scaffold favored C2C12 myoblast differentiation, the annatto-loaded CA scaffold favored a proliferative state of these cells. These results suggest that the combination of cellulose acetate fibers loaded with annatto extract may be an interesting economical alternative for support long-term muscle cells culture with potential application as scaffold for cultivated meat and muscle tissue engineering.