The intervertebral disc (IVD) exhibits time-dependent mechanical behaviour that is central to load redistribution and tissue integrity, yet the regional contributions of distinct interfacial tissues remain poorly understood. In this study, we compared the stress-relaxation behaviour of two mechanically critical IVD interfaces, the interlamellar matrix (ILM) and the nucleus pulposus-annulus fibrosus interface (transition zone; TZ), to quantify differences in relaxation magnitude, kinetics, and cumulative mechanical exposure. Isolated ovine ILM and TZ specimens underwent controlled radial stress-relaxation testing under maintained hydration, with responses analysed using model-independent metrics and complementary Peleg and Kohlrausch-Williams-Watts modelling. The ILM exhibited significantly higher initial and apparent equilibrium stresses, prolonged relaxation timescales, and substantially greater cumulative stress exposure, consistent with sustained load retention. In contrast, the TZ showed rapid early stress decay, lower residual stress, and greater relative stress dissipation. Viscoelastic modelling indicated longer characteristic relaxation times in the ILM than the TZ, whereas no statistically significant regional difference in the stretch exponent β was detected within the experimental timeframe.

The generation of wear debris from orthopedic implants is a known cause of implant failure, particularly in joint replacements. While much research has focused on wear particles from knee and hip implants, spinal implants, such as total disc replacements (TDRs), have received less attention despite their increasing clinical use. Spinal implants face unique biomechanical challenges, including a wider range of motion and higher loads, leading to complex tissue interactions. Studies reveal that TDR wear particles, though similar in size to those from knee implants, cause a stronger immune response, with more macrophages and giant cells found in the surrounding tissue. This may explain the high revision rates seen in spinal surgeries, with some interventions failing in over 30% of cases within 10 years. The younger population undergoing spinal surgery, combined with the productivity losses associated with implant failure, underscores the need for greater understanding. This review discusses recent research on the generation, characterization, and biological impacts of spinal implant wear debris. It draws on retrieval analysis, wear simulation, in vivo models, and a survey conducted with the AO Spine Knowledge Forum Degenerative to assess current clinical practices and highlight gaps in knowledge. Additionally, this critical review explores future strategies to reduce the biological impact of wear particles and improve the safety and longevity of spinal implants through better therapeutics and design innovations. By combining literature and clinical insights, this paper aims to guide future research in addressing the complexities of spinal implant wear and its biological consequences.

Spinal implants are vital for treating spinal disorders, yet wear particle-induced complications threaten their long-term success. Despite this, the direct effects of implant-derived particles on neural cells remain largely unexplored, especially given the limitations of conventional 2D culture models to capture such complex interactions. The current study introduces a novel in vitro platform consisting of a 3D bioprinted GelMA hydrogel embedded with neural cells (C6 astrocyte-like and NG108-15 neurons) and spinal implant biomaterial particles, designed to model the spinal cord microenvironment with enhanced physiological relevance. As the first of its kind, this cell-particle-laden system supports the evaluation of neural cell responses to spinal biomaterial particles, including polymers, PEEK-Optima and polyethylene Ceridust® 3615, zirconia toughened alumina (ZTA) ceramic, and CoCrMo metal alloy. The bioprinted platform demonstrated excellent compatibility with various neural cell types and particle compositions, enabling a wide range of biological assays. Cell viability within the 3D model was comparable to traditional 2D cultures, affirming its ability to sustain cell survival while offering improved biomimicry. Biological assays assessing cell viability, reactive oxygen species (ROS) production and DNA damage provided critical insights into material-specific and time-dependent cellular responses. While no significant cytotoxic effects were observed in short-term cultures, distinct variations in ROS production and viability emerged based on biomaterial type and exposure duration. Overall, this versatile 3D bioprinted system presents a robust, scalable tool for mechanistic and toxicological studies of spinal implant wear particles under physiologically relevant conditions.

In recent years, the substantial increase in total joint replacements for treating degenerative joint disease has heightened concerns regarding implant loosening and failure. This is especially critical as more young patients are undergoing both initial and subsequent joint replacement procedures. These complications often necessitate additional revision surgeries. Unfortunately, current clinical practices lack effective methods for the early detection of implant failure, and there is a noticeable absence of strategies utilizing molecular markers to identify post-surgery implant issues. This article critically assesses the potential of aggregation-induced emission (AIE) biomarkers in detecting molecular markers relevant to implant failure. It begins by outlining the pathogenesis of implant loosening and identifying pertinent molecular markers. The study then delves into how AIE luminogens (AIEgens) can play a crucial role in detecting processes such as osteogenesis and osteoclastogenesis. Notably, it discusses the utilization of AIEgens in detecting key molecular markers, including TNF-α, osteocalcin, and urinary N-terminal telopeptide. The prospect of AIE biomarkers for the early detection of bone loss and implant failure presents a promising avenue for enhancing our understanding of skeletal health and improving clinical outcomes through timely intervention and personalized treatment approaches. Ongoing research and development in this area are crucial for translating AIE-based technologies into practical tools for optimizing bone health management.

Study Design Systematic Review. Objectives To systematically review the clinical outcomes, re-operation, and complication rates of lumbar TDR devices at mid-to long-term follow-up studies for the treatment of lumbar degenerative disc disease (DDD). Methods A systematic search was conducted on PubMed, SCOPUS, and Google Scholar to identify follow-up studies that evaluated clinical outcomes of lumbar TDR in patients with DDD. The included studies met the following criteria: prospective or retrospective studies published from 2012 to 2022; a minimum of 5 years post-operative follow-up; a study sample size >10 patients; patients >18 years of age; containing clinical outcomes with Oswestry Disability Index (ODI), Visual Analog Scale (VAS), complication or reoperation rates. Results Twenty-two studies were included with data on 2284 patients. The mean follow-up time was 8.30 years, with a mean follow-up rate of 86.91%. The study population was 54.97% female, with a mean age of 42.34 years. The mean VAS and ODI pain score improvements were 50.71 ± 6.91 and 30.39 ± 5.32 respectively. The mean clinical success and patient satisfaction rates were 74.79% ± 7.55% and 86.34% ± 5.64%, respectively. The mean complication and reoperation rates were 18.53% ± 6.33% and 13.6% ± 3.83%, respectively. There was no significant difference when comparing mid-term and long-term follow-up studies for all clinical outcomes. Conclusions There were significant improvements in pain reduction at last follow-up in patients with TDRs. Mid-term follow-up data on clinical outcomes, complication and reoperation rates of lumbar TDRs were maintained longer term.

Silk fibroin (SF) is a natural protein extracted from Bombyx mori silkworm thread. From its common use in the textile industry, it emerged as a biomaterial with promising biochemical and mechanical properties for applications in the field of tissue engineering and regenerative medicine. In this study, we evaluate for the first time the effects of SF on cardiac bioink formulations containing cardiac spheroids (CSs). First, we evaluate if the SF addition plays a role in the structural and elastic properties of hydrogels containing alginate (Alg) and gelatin (Gel). Then, we test the printability and durability of bioprinted SF-containing hydrogels. Finally, we evaluate whether the addition of SF controls cell viability and function of CSs in Alg-Gel hydrogels. Our findings show that the addition of 1% (w/v) SF to Alg-Gel hydrogels makes them more elastic without affecting cell viability. However, fractional shortening (FS%) of CSs in SF-Alg-Gel hydrogels increases without affecting their contraction frequency, suggesting an improvement in contractile function in the 3D cultures. Altogether, our findings support a promising pathway to bioengineer bioinks containing SF for cardiac applications, with the ability to control mechanical and cellular features in cardiac bioinks.

The stress relaxation of the TZ region, located at the interface of the Annulus Fibrosus (AF) and Nucleus Pulposus (NP) of the disc, and how its stress is relaxed compared to the adjacent regions is unknown. The current study aimed to identify the TZ stress relaxation properties under different strain magnitudes (0.2, 0.4, and 0.6 mm/mm) and compared the TZ stress relaxation characteristics to the NP and inner AF (IAF) regions at a specific strain magnitude (0.6 mm/mm). The results of the current study revealed that the TZ region exhibited different stress relaxation properties under various strain magnitudes with significantly higher initial ( p < 0.008) and reduced stresses (marginally; p = 0.06) at higher strains. Our experimental stress relaxation data revealed a significantly higher equilibrium stress for the IAF compared to the TZ and NP regions ( p < 0.001) but not between the TZ and NP regions ( p = 0.7). We found that NP radial stress relaxed significantly faster ( p < 0.04) than the TZ and NP. Additionally, the current study proposed a simple mathematical model and identified that, consistent with experimental data, the overall effect of region on both the level of decayed stress and the rate at which stress is relaxed was significant ( p < 0.006). The current study found a similar stress relaxation characteristic between the NP and TZ regions, while IAF exhibited different stress relaxation properties. It is possible that this mismatch in stress relaxation acts as a shape transformation mechanism triggered by viscoelastic behavior.

Current in vitro intervertebral disc (IVD) models do not fully recapitulate the complex mechanobiology of native tissue, and so far there is no strategy to effectively evaluate IVD regeneration. The development of a modular microfluidic on-chip model is expected to enhance the physiological relevance of experimental data leading to successful clinical outcomes.

Effective contraceptives have been comprehensively adopted by women to prevent the negative consequences of unintended pregnancy for women, families, and societies. With great contributions of traditional hormonal drugs and intrauterine devices (IUDs) to effective female contraception by inhibiting ovulation and deactivating sperm, their long-standing side effects on hormonal homeostasis and reproductive organs for females remain concerns. Herein, we proposed a nanostrategy for female contraceptives, inducing embryonic trophoblast cell death using nanoparticles to prevent embryo implantation. Cupric oxide nanoparticles (CuO NPs) were adopted in this work to verify the feasibility of the nanostrategy and its contraceptive efficacy. We carried out the in vitro assessment on the interaction of CuO NPs with trophoblast cells using the HTR8/SVneo cell line. The results showed that the CuO NPs were able to be preferably uptaken into cells and induced cell damage via a variety of pathways including oxidative stress, mitochondrial damage, DNA damage, and cell cycle arrest to induce cell death of apoptosis, ferroptosis, and cuproptosis. Moreover, the key regulatory processes and the key genes for cell damage and cell death caused by CuO NPs were revealed by RNA-Seq. We also conducted in vivo experiments using a rat model to examine the contraceptive efficacy of both the bare CuO NPs and the CuO/thermosensitive hydrogel nanocomposite. The results demonstrated that the CuO NPs were highly effective for contraception. There was no sign of disrupting the homeostasis of copper and hormone, or causing inflammation and organ damage in vivo. In all, this nanostrategy exhibited huge potential for contraceptive development with high biosafety, efficacy, clinical translation, nonhormonal style, and on-demand for women.

Introduction: Polymer wear debris is one of the major concerns in total joint replacements due to wear-induced biological reactions which can lead to osteolysis and joint failure. The wear-induced biological reactions depend on the wear volume, shape and size of the wear debris and their volumetric concentration. The study of wear particles is crucial in analysing the failure modes of the total joint replacements to ensure improved designs and materials are introduced for the next generation of devices. Existing methods of wear debris analysis follow a traditional approach of computer-aided manual identification and segmentation of wear debris which encounters problems such as significant manual effort, time consumption, low accuracy due to user errors and biases, and overall lack of insight into the wear regime.Methods: This study proposes an automatic particle segmentation algorithm using adaptive thresholding followed by classification using Convolution Neural Network (CNN) to classify ultra-high molecular weight polyethylene polymer wear debris generated from total disc replacements tested in a spine simulator. A CNN takes object pixels as numeric input and uses convolution operations to create feature maps which are used to classify objects.Results: Classification accuracies of up to 96.49% were achieved for the identification of wear particles. Particle characteristics such as shape, size and area were estimated to generate size and volumetric distribution graphs.Discussion: The use of computer algorithms and CNN facilitates the analysis of a wider range of wear debris with complex characteristics with significantly fewer resources which results in robust size and volume distribution graphs for the estimation of the osteolytic potential of devices using functional biological activity estimates.

Aseptic loosening and osteolysis continue to be a short- to mid-term problem for total ankle replacement (TAR) devices. The production of wear particles may contribute to poor performance, but their characteristics are not well understood. This study aimed to determine the chemical composition, size and morphology of wear particles surrounding failed TARs. A recently developed wear particle isolation method capable of isolating both high- and low-density materials was applied to 20 retrieved periprosthetic tissue samples from 15 failed TARs of three different brands. Isolated particles were imaged using ultra-high-resolution imaging and characterised manually to determine their chemical composition, size, and morphology. Six different materials were identified, which included: UHMWPE, calcium phosphate (CaP), cobalt chromium alloy (CoCr), commercially pure titanium, titanium alloy and stainless steel. Eighteen of the 20 samples contained three or more different wear particle material types. In addition to sub-micron UHMWPE particles, which were present in all samples, elongated micron-sized shards of CaP and flakes of CoCr were commonly isolated from tissues surrounding AES TARs. The mixed particles identified in this study demonstrate the existence of a complex periprosthetic environment surrounding TAR devices. The presence of such particles suggests that early failure of devices may be due in part to the multifaceted biological cascade that ensues after particle release. This study could be used to support the validation of clinically-relevant wear simulator testing, pre-clinical assessment of fixation wear and biological response studies to improve the performance of next generation ankle replacement devices. STATEMENT OF SIGNIFICANCE: Total ankle replacement devices do not perform as well as total hip and knee replacements, which is in part due to the relatively poor scientific understanding of how they fail. The excessive production of certain types of wear debris is known to contribute to joint replacement failure. This is the first study to successfully isolate and characterise high- and low-density wear particles from tissues collected from patients with a failed total ankle replacement. This article includes the chemical composition and characteristics of the wear debris generated by ankle devices, all of which may affect their performance. This research provides clinically relevant reference values and images to support the development of pre-clinical testing for future total ankle replacement designs.

This paper presents the engineering and validation of an enabling technology that facilitates new capabilities in in vitro cell models for high-throughput screening and tissue engineering applications. This is conducted through a computerized system that allows the design and deposition of high-fidelity microscale patterned coatings that selectively alter the chemical and topographical properties of cell culturing surfaces. Significantly, compared to alternative methods for microscale surface patterning, this is a digitally controlled and automated process thereby allowing scientists to rapidly create and explore an almost infinite range of cell culture patterns. This new capability is experimentally validated across six different cell lines demonstrating how the precise microscale deposition of these patterned coatings can influence spatiotemporal growth and movement of endothelial, fibroblast, neuronal and macrophage cells. To further demonstrate this platform, more complex patterns are then created and shown to guide the behavioral response of colorectal carcinoma cells.

Understanding the structure-function relationship in the intervertebral disk (IVD) is crucial for the de-velopment of novel tissue engineering strategies to regenerate IVD and the establishment of accurate computational models for low back pain research. A large number of studies have improved our knowl-edge of the mechanical and structural properties of the nucleus pulposus (NP) and annulus fibrosus (AF), two of the main regions in the IVD. However, few studies have focused on the AF-NP interface (transi-tion zone; TZ). Therefore, the current study aims to, for the first time, characterize the cyclic and failure mechanical properties of the TZ region under physiological loading (1, 3, and 5%s-1 strain rates) and in-vestigate the structural integration mechanisms between the NP, TZ, and AF regions. The results of the current study reveal significant effects of region (NP, TZ, and AF) and strain rates (1, 3, and 5%s-1) on stiffness ( p < 0.001). In addition, energy absorption is significantly higher for the AF compared to the TZ and NP ( p < 0.001) as well as between the TZ and NP ( p < 0.001). The current research finds adapta-tion, direct penetration, and entanglement between TZ and AF fibers as three common mechanisms for structural integration between the TZ and AF regions. Statement of significance Despite a large number of studies that have mechanically, structurally, and biologically characterized the nucleus pulposus (NP) and annulus fibrosus (AF) regions, few studies have focused on the NP-AF interface region (known as Transition Zone; TZ) in the IVD; hence, our understanding of the TZ structure-function relationship is still incomplete. Of particular importance, the cyclic mechanical properties of the TZ, com-pared to the adjacent regions (NP and AF), are yet to be explored and the precise nature of the structural integration between the NP and AF via the TZ region is not yet known. The current study explores both the mechanical and structural properties of the TZ region to ultimately identify the mechanism of inte-gration between the NP and AF. (c) 2023 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Biofabrication of three-dimensional (3D) in vitro neural cell models that closely mimic the central nervous system (CNS) is an emerging field of research with applications from fundamental biology to regenerative medicine, and far reaching benefits for the economy, healthcare and the ethical use of animals. The micromechanical properties of such models are an important factor dictating the success of modelling outcomes in relation to accurate reproduction of the processes in native tissues. Characterising the micromechanical properties of such models non-destructively and over a prolonged span of time, however, are key challenges. Brillouin microspectroscopy (BM) could provide a solution to this problem since this technology is non-invasive, label-free and is capable of micro-scale 3D imaging. In this work, the micromechanical properties of 3D bioprinted neural cell models consisting of NG 108-15 neuronal cells and Gelatin methacryloyl (GelMA) hydrogels of various concentrations were investigated using BM. We demonstrate changes in the volume-averaged (VA) and local micro-scale mechanical properties of these models over a 7 day period, in which the hydrogel component of the model are found to soften as the cells grow, multiply and form stiffer spheroid-type structures. These findings signify the necessity to resolve in microscopic detail the mechanics of in vitro 3D tissue models and suggest Brillouin microspectroscopy to be a suitable technology to bridge this gap.

The Nucleus Pulposus (NP) and Annulus Fibrous (AF) are two primary regions of the intervertebral disc (IVD). The interface between the AF and NP, where the gradual transition in structure and type of fibers are observed, is known as the Transition Zone (TZ). Recent structural studies have shown that the TZ contains organized fibers that appear to connect the NP to the AF. However, the mechanical characteristics of the TZ are yet to be explored. The current study aimed to investigate the mechanical properties of the TZ at the anterolateral (AL) and posterolateral (PL) regions in both radial and circumferential directions of loading using ovine IVDs (N = 28). Young's and toe moduli, maximum stress, failure strain, strain at maximum stress, and toughness were calculated mechanical parameters. The findings from this study revealed that the mechanical properties of the TZ, including young's modulus (p = 0.001), failure strain (p < 0.001), strain at maximum stress (p = 0.002), toughness (p = 0.027), and toe modulus (p = 0.005), were significantly lower for the PL compared to the AL region. Maximum stress was not significantly different between the PL and AL regions (p = 0.164). We found that maximum stress (p = 0.002), failure strain (p < 0.001), and toughness (p = 0.001) were significantly different in different loading directions. No significant differences for modulus (young's; p = 0.169 and toe; p = 0.352) and strain at maximum stress (p = 0.727) were found between the radial and circumferential loading directions. Statement of significance To date there has not been a study that has investigated the mechanical characterization of the annulus (AF)-nucleus (NP) interface (transition zone; TZ) in the intervertebral disc (IVD), nor is it known whether the posterolateral (PL) and anterolateral (AL) regions of the TZ exhibit different mechanical properties. Accordingly, the TZ mechanical properties have been rarely used in the development of computational IVD models and relevant tissue-engineered scaffolds. The current research reported the mechanical properties of the TZ region and revealed that its mechanical properties were significantly lower for the PL compared to the AL region. These new findings enhance our knowledge about the nature of AF-NP integration and may help to develop more realistic tissue-engineered or computational IVD models. (c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The current study describes a new technology, effective for readily preparing a fluorescent (FL) nanoprobe-based on hyperbranched polymer (HB) and aggregation-induced emission (AIE) fluorogen with high brightness to ultimately develop FL hydrogels. We prepared the AIE nanoprobe using a microfluidic platform to mix hyperbranched polymers (HB, generations 2, 3, and 4) with AIE (TPE-2BA) under shear stress and different rotation speeds (0-5 K RPM) and explored the FL properties of the AIE nanoprobe. Our results reveal that the use of HB generation 4 exhibits 30-times higher FL intensity compared to the AIE alone and is significantly brighter and more stable compared to those that are prepared using HB generations 3 and 2. In contrast to traditional methods, which are expensive and time-consuming and involve polymerization and post-functionalization to develop FL hyperbranched molecules, our proposed method offers a one-step method to prepare an AIE-HB nanoprobe with excellent FL characteristics. We employed the nanoprobe to fabricate fluorescent injectable bioadhesive gel and a hydrogel microchip based on polyvinyl alcohol (PVA). The addition of borax (50 mM) to the PVA + AIE nanoprobe results in the development of an injectable bioadhesive fluorescent gel with the ability to control AIEgen release for 300 min. When borax concentration increases two times (100 mM), the adhesion stress is more than two times bigger (7.1 mN/mm(2)) compared to that of gel alone (3.4 mN/mm(2)). Excellent dimensional stability and cell viability of the fluorescent microchip, along with its enhanced mechanical properties, proposes its potential applications in mechanobiology and understanding the impact of microstructure in cell studies.

Hip and knee joint replacements are common and largely successful procedures that utilise implants to restore mobility and relieve pain for patients suffering from e.g. osteoarthritis. However, metallic ions and particles released from both the bearing surfaces and non-articulating interfaces, as in modular components, can cause hypersensitivity and local tissue necrosis, while particles originating from a polymer component have been associated with aseptic loosening and osteolysis. Implant coatings have the potential to improve properties compared to both bulk metal and ceramic alternatives. Ceramic coatings have the potential to increase scratch resistance, enhance wettability and reduce wear of the articulating surfaces compared to the metallic substrate, whilst maintaining overall toughness of the implant ensuring a lower risk of catastrophic failure of the device compared to use of a bulk ceramic. Coatings can also act as barriers to inhibit ion release from the underlying material caused by corrosion. This review aims to provide a comprehensive overview of wear-resistant coatings for joint replacements - both those that are in current clinical use as well as those under investigation for future use. While the majority of coatings belong predominantly in the latter group, a few coated implants have been successfully marketed and are available for clinical use in specific applications. Commercially available coatings for implants include titanium nitride (TiN), titanium niobium nitride (TiNbN), oxidized zirconium (OxZr) and zirconium nitride (ZrN) based coatings, whereas current research is focused not only on these, but also on diamond-like-carbon (DLC), silicon nitride (SiN), chromium nitride (CrN) and tantalum-based coatings (TaN and TaO). The coating materials referred to above that are still at the research stage have been shown to be non-cytotoxic and to reduce wear in a laboratory setting. However, the adhesion of implant coatings remains a main area of concern, as poor adhesion can cause delamination and excessive wear. In clinical applications zirconium implant surfaces treated to achieve a zirconium oxide film and TiNbN coated implants have however been proven comparable to traditional cobalt chromium implants with regards to revision numbers. In addition, the chromium ion levels measured in the plasma of patients were lower and allergy symptoms were relieved. Therefore, coated implants could be considered an alternative to uncoated metal implants, in particular for patients with metal hypersensitivity. There have also been unsuccessful introductions to the market, such as DLC coated implants, and therefore this review also attempts to summarize the lessons learnt.

Submicron-sized wear particles are generally accepted as a potential cause of aseptic loosening when produced in sufficient volumes. With the accelerating use of increasingly wear-resistant biomaterials, identifying such particles and evaluating their biological response is becoming more challenging. Highly sensitive wear particle isolation methods have been developed but these methods cannot isolate the complete spectrum of particle types present in individual tissue samples. Two established techniques were modified to create one novel method to isolate both high- and low-density materials from periprosthetic tissue samples. Ten total hip replacement and eight total knee replacement tissue samples were processed. All particle types were characterized using high resolution scanning electron microscopy. UHMWPE and a range of high-density materials were isolated from all tissue samples, including: polymethylmethacrylate, zirconium dioxide, titanium alloy, cobalt chromium alloy and stainless steel. This feasibility study demonstrates the coexistence of mixed particle types in periprosthetic tissues and provides researchers with high-resolution images of clinically relevant wear particles that could be used as a reference for future in vitro biological response studies.

In clinical trials, new scaffolds for regeneration after spinal cord injury (SCI) should reflect the importance of a mechanically optimised, hydrated environment. Composite scaffolds of nonwovens, self-assembling peptides (SAPs) and hydrogels offer the ability to mimic native spinal cord tissue, promote aligned tissue regeneration and tailor mechanical properties. This work studies the effects of an aligned electrospun nonwoven of P11-8—enriched poly(ε-caprolactone) (PCL) fibres, integrated with a photo-crosslinked hydrogel of glycidylmethacrylated collagen (collagen-GMA), on neurite extension. Mechanical properties of collagen-GMA hydrogel in compression and shear were recorded, along with cell viability. Collagen-GMA hydrogels showed J-shaped stress–strain curves in compression, mimicking native spinal cord tissue. For hydrogels prepared with a 0.8-1.1 wt.% collagen-GMA concentration, strain at break values were 68 ± 1–81 ± 1% (±SE); maximum stress values were 128 ± 9–311 ± 18 kPa (±SE); and maximum force values were 1.0 ± 0.1–2.5 ± 0.1 N (±SE). These values closely mimicked the compression values for feline and porcine tissue in the literature, especially those for 0.8 wt.%. Complex shear modulus values fell in the range 345–2588 Pa, with the lower modulus hydrogels in the range optimal for neural cell survival and growth. Collagen-GMA hydrogel provided an environment for homogenous and three-dimensional cell encapsulation, and high cell viability of 84 ± 2%. Combination of the aligned PCL/P11-8 electrospun nonwoven and collagen-GMA hydrogel retained fibre alignment and pore structure, respectively, and promoted aligned neurite extension of PC12 cells. Thus, it is possible to conclude that scaffolds with mechanical properties that both closely mimic native spinal cord tissue and are optimal for neural cells can be produced, which also promote aligned tissue regeneration when the benefits of hydrogels and electrospun nonwovens are combined.

The current research aimed to fabricate an alginate-hyperbranched polymer (HBP) complex, using a vortex fluidic device (VFD), to control the physicochemical, structural, and mechanical properties of alginate hydrogel; thus, providing a dominant biomaterial system for different biomedical applications. Samples were prepared by mixing alginate (6%w/w) with HBP (0.85 mu M) before cross-linking with Ca2+ (100 mM). Magnet stirrer (600 rpm) and VFD (6000 rpm) were used to prepare experimental samples, and alginate was used as control. Comprehensive evaluations of bulk and surface morphology, microstructural analysis, swelling kinetics, mechanical characteristics, cytotoxicity, and formation of hydrogen bonds were conducted. The findings from this study revealed that the addition of HBP to alginate structure led to a higher swelling capability (86%), increased diffusion coefficient (66-fold), and enhanced failure mechanical properties (160% and 20% increases for failure stress and elongation at break, respectively) than control. Traditional mixing affected the surface morphology, while the bulk structure remained unchanged. Moreover, the rate of degradation was not significantly different between alginate and alginate-HBP samples. When VFD was incorporated, a higher swelling ratio (30%) was observed than the control sample and the coefficient of diffusion increased (34-fold). The associated degradation rate increased 30-fold, and the failure stress and elongation at break were increased 310% and 83%, respectively, compared to the control sample. The micromixing of alginate with HBP under high shear stress using a VFD created a micro-hybrid composite formed by alginate microparticles embedded in an alginate sheet. (C) 2021 Elsevier Ltd. All rights reserved.