Electrically conductive carbon-based (bio)-nanomaterials for cardiac tissue engineering

Fabrication and preliminary characterization of conductive nanofillers-enhanced polymeric hydrogels for cardiac patch applications

The development of conducting polymeric nanocomposites patches for cardiac tissue engineering has opened new possibilities for restoring the health of infarcted heart tissues. Herein, we report the fabrication of biocompatible and relatively cost-effective poly(vinyl alcohol)/alginate-based hydrogels patches modified with different conducting nanofillers such as silver nanoparticles, polyaniline nanofibers, copper oxide nanoleaves, and graphene oxide nanosheets. The impact of the different nanofiller materials on the molecular structure, charge transport mechanism and mechanical characteristics of the designed nanocomposites patches was investigated. In addition, some significant parameters of the nanocomposites were characterized such as swelling ability, antioxidant activity as well as hemocompatibility. Infrared spectroscopy results demonstrated the occurrence of different interactions between the included nanofillers and the polymer matrix depending on the type of the nanofiller. Moreover, conductivity measurements revealed that only the polyaniline nanofibers-modified nanocomposites hydrogels showed the highest conductivity compared to other counterparts. Mechanical characterization, antioxidant activity, swelling and hemocompatibility proved the suitability of the developed polyaniline nanofibers-modified nanocomposites hydrogels as potential candidates for successful application in cardiac tissue engineering.

Physico-chemical and spectroscopic characterization of hyaluronic acid hydrogels crosslinked with 1,4-butanediol diglycidyl ether (BDDE)

Three hyaluronic acid (HA) - based hydrogels at different HA/1,4-butanediol diglycidyl ether (BDDE) ratios were prepared, and their network characterization and drug release properties were studied. Amoxicillin (AMX) loading and release behavior of the hydrogels were investigated as a function of cross-link density. The percentage release of amoxicillin increased as the cross-link density decreased. In the network characterization, the polymer-solvent interaction parameter (χ) of HA in PBS (pH 7.4) at 25 °C was determined to be 0.418 ± 0.002 from Zimm plot using light-scattering technique. The number average molecular weight between junction points of the hydrogels (Mc¯) was calculated as a function of the HA/BDDE ratio using Flory-Rehner theory. The crosslinking reaction of HA with BDDE was monitored in real-time by 1H NMR spectroscopy, which indicated that the reaction was completed in 55.5 h at 37 °C.

Nanomaterial-functionalized electrospun scaffolds for tissue engineering

Tissue engineering has emerged as a biological alternative aimed at sustaining, rehabilitating, or enhancing the functionality of tissues that have experienced partial or complete loss of their operational capabilities. The distinctive characteristics of electrospun nanofibrous structures, such as their elevated surface-area-to-volume ratio, specific pore sizes, and fine fiber diameters, make them suitable as effective scaffolds in tissue engineering, capable of mimicking the functions of the targeted tissue. However, electrospun nanofibers, whether derived from natural or synthetic polymers or their combinations, often fall short of replicating the multifunctional attributes of the extracellular matrix (ECM). To address this, nanomaterials (NMs) are integrated into the electrospun polymeric matrix through various functionalization techniques to enhance their multifunctional properties. Incorporation of NMs into electrospun nanofibrous scaffolds imparts unique features, including a high surface area, superior mechanical properties, compositional variety, structural adaptability, exceptional porosity, and enhanced capabilities for promoting cell migration and proliferation. This review provides a comprehensive overview of the various types of NMs, the methodologies used for their integration into electrospun nanofibrous scaffolds, and the recent advancements in NM-functionalized electrospun nanofibrous scaffolds aimed at regenerating bone, cardiac, cartilage, nerve, and vascular tissues. Moreover, the main challenges, limitations, and prospects in electrospun nanofibrous scaffolds are elaborated.

Anisotropic conductive scaffolds for post-infarction cardiac repair

Myocardial infarction (MI) remains one of the most common and lethal cardiovascular diseases (CVDs), leading to the deterioration of cardiac function due to myocardial cell necrosis and fibrous scar tissue formation. Myocardial infarction (MI) remains one of the most common and lethal cardiovascular diseases (CVDs), leading to the deterioration of cardiac function due to myocardial cell necrosis and fibrous scar tissue formation. After MI, the anisotropic structural properties of myocardial tissue are destroyed, and its mechanical and electrical microenvironment also undergoes a series of pathological changes, such as ventricular wall stiffness, abnormal contraction, conduction network disruption, and irregular electrical signal propagation, which may further induce myocardial remodeling and even lead to heart failure. Therefore, bionic reconstruction of the anisotropic structural-mechanical-electrical microenvironment of the infarct area is key to repairing damaged myocardium. This article first summarizes the pathological changes in muscle fibre structure and conductive microenvironment after cardiac injury, and focuses on the classification and preparation methods of anisotropic conductive materials. In addition, the effects of these anisotropic conductive materials on the behavior of cardiac resident cells after myocardial infarction, such as directional growth, maturation, proliferation and migration, and the differentiation fate of stem cells and the possible molecular mechanisms involved are summarized. The design strategies for anisotropic conductive scaffolds for myocardial repair in future clinical research are also discussed, with the aim of providing new insights for researchers in related fields.

Electrically Active Biomaterials for Stimulation and Regeneration in Tissue Engineering

In the human body, bioelectric cues are crucial for tissue stimulation and regeneration. Electrical stimulation (ES) significantly enhances the regeneration of nerves, bones, cardiovascular tissues, and wounds. However, the use of conventional devices with stimulating metal electrodes is invasive and requires external batteries. Consequently, electrically active materials with excellent biocompatibility have attracted attention for their applications in stimulation and regeneration in tissue engineering. To fully exploit the potential of these materials, biocompatibility, operating mechanisms, electrical properties, and even biodegradability should be carefully considered. In this review, we categorize various electrically active biomaterials based on their mechanisms for generating electrical cues, such as piezoelectric effect, triboelectric effect, and others. We also summarize the key material properties, including electrical characteristics and biodegradability, and describe their applications in tissue stimulation and regeneration for nerves, musculoskeletal tissues, and cardiovascular tissues. The electrically active biomaterials hold great potential for advancing the field of tissue engineering and their demonstrated success underscores the importance of continued research in this field.

Stem cells and bio scaffolds for the treatment of cardiovascular diseases: new insights

Mortality and morbidity from cardiovascular diseases are common worldwide. In order to improve survival and quality of life for this patient population, extensive efforts are being made to establish effective therapeutic modalities. New treatment options are needed, it seems. In addition to treating cardiovascular diseases, cell therapy is one of the most promising medical platforms. One of the most effective therapeutic approaches in this area is stem cell therapy. In stem cell biology, multipotent stem cells and pluripotent stem cells are divided into two types. There is evidence that stem cell therapy could be used as a therapeutic approach for cardiovascular diseases based on multiple lines of evidence. The effectiveness of stem cell therapies in humans has been studied in several clinical trials. In spite of the challenges associated with stem cell therapy, it appears that resolving them may lead to stem cells being used in cardiovascular disease patients. This may be an effective therapeutic approach. By mounting these stem cells on biological scaffolds, their effect can be enhanced.

Electroactive Nanomaterials for the Prevention and Treatment of Heart Failure: From Materials and Mechanisms to Applications

Heart failure (HF) represents a cardiovascular disease that significantly threatens global well-being and quality of life. Electroactive nanomaterials, characterized by their distinctive physical and chemical properties, emerge as promising candidates for HF prevention and management. This review comprehensively examines electroactive nanomaterials and their applications in HF intervention. It presents the definition, classification, and intrinsic characteristics of conductive, piezoelectric, and triboelectric nanomaterials, emphasizing their mechanical robustness, electrical conductivity, and piezoelectric coefficients. The review elucidates their applications and mechanisms: 1) early detection and diagnosis, employing nanomaterial-based sensors for real-time cardiac health monitoring; 2) cardiac tissue repair and regeneration, providing mechanical, chemical, and electrical stimuli for tissue restoration; 3) localized administration of bioactive biomolecules, genes, or pharmacotherapeutic agents, using nanomaterials as advanced drug delivery systems; and 4) electrical stimulation therapies, leveraging their properties for innovative pacemaker and neurostimulation technologies. Challenges in clinical translation, such as biocompatibility, stability, and scalability, are discussed, along with future prospects and potential innovations, including multifunctional and stimuli-responsive nanomaterials for precise HF therapies. This review encapsulates current research and future directions concerning the use of electroactive nanomaterials in HF prevention and management, highlighting their potential to innovating in cardiovascular medicine.

A Review of Advanced Hydrogel Applications for Tissue Engineering and Drug Delivery Systems as Biomaterials

Hydrogels are known for their high water retention capacity and biocompatibility and have become essential materials in tissue engineering and drug delivery systems. This review explores recent advancements in hydrogel technology, focusing on innovative types such as self-healing, tough, smart, and hybrid hydrogels, each engineered to overcome the limitations of conventional hydrogels. Self-healing hydrogels can autonomously repair structural damage, making them well-suited for applications in dynamic biomedical environments. Tough hydrogels are designed with enhanced mechanical properties, enabling their use in load-bearing applications such as cartilage regeneration. Smart hydrogels respond to external stimuli, including changes in pH, temperature, and electromagnetic fields, making them ideal for controlled drug release tailored to specific medical needs. Hybrid hydrogels, made from both natural and synthetic polymers, combine bioactivity and mechanical resilience, which is particularly valuable in engineering complex tissues. Despite these innovations, challenges such as optimizing biocompatibility, adjusting degradation rates, and scaling up production remain. This review provides an in-depth analysis of these emerging hydrogel technologies, highlighting their transformative potential in both tissue engineering and drug delivery while outlining future directions for their development in biomedical applications.

Electrically conductive nanomaterials: transformative applications in biomedical engineering-a review

In recent years, significant advancements in nanotechnology have improved the various disciplines of scientific fields. Nanomaterials, like, carbon-based (carbon nanotubes, graphene), metallic, metal oxides, conductive polymers, and 2D materials (MXenes) exhibit exceptional electrical conductivity, mechanical strength, flexibility, thermal property and chemical stability. These materials hold significant capability in transforming material science and biomedical engineering by enabling the creation of more efficient, miniaturized, and versatile devices. The indulgence of nanotechnology with conductive materials in biological fields promises a transformative innovation across various industries, from bioelectronics to environmental regulations. The conductivity of nanomaterials with a suitable size and shape exhibits unique characteristics, which provides a platform for realization in bioelectronics as biosensors, tissue engineering, wound healing, and drug delivery systems. It can be explored for state-of-the-art cardiac, skeletal, nerve, and bone scaffold fabrication while highlighting their proof-of-concept in the development of biosensing probes and medical imaging. This review paper highlights the significance and application of the conductive nanomaterials associated with conductivity and their contribution towards a new perspective in improving the healthcare system globally.

Carbon Fiber-Mediated Electrospinning Scaffolds Can Conduct Electricity for Repairing Defective Tendon

Partial or complete rupture of the tendon can damage the collagen structure, resulting in the disruption of the electrical signal pathway. It is a great challenge to reconstruct the original electrical signal pathway of the tendon and promote the regeneration and functional recovery of defective tendon. In this study, carbon fiber-mediated electrospinning scaffolds were fabricated by wrapping conductive, high-strength, loose single-bundle carbon fibers with nanofiber membranes. Due to the presence of nanofiber membranes, the maximum tensile force of the scaffolds was 2.4 times higher than that of carbon fibers, while providing excellent temporal and spatial prerequisites for tenocytes to adapt to electrical stimulation to accelerate proliferation and expression. The diameter of the carbon fiber monofilaments used in this study was 5.07 ± 1.20 μm, which matched the diameter of tendon collagen, allowing for quickly establishing the connection between the tendon tissue and the scaffold, and better promoting the recovery of the electrical signal pathway. In a rabbit Achilles tendon defect repair model, the carbon fiber-mediated electrospinning scaffold was almost filled with collagen fibers compared to a nonconductive polyethylene glycol terephthalate scaffold. Transcriptome sequencing revealed that fibromodulin and tenomodulin expression were upregulated, and their related proteoglycans and glycosaminoglycan binding proteins pathways were enhanced, which could regulate the TGF-β signaling pathway and optimize the extracellular matrix assembly, thus promoting tendon repair. Therefore, the scaffold in this study makes up for the shortage of conductive scaffolds for repairing tendon defects, revealing the potential impact of conductivity on the signaling pathway of tendon repair and providing a new approach for future clinical studies.

Brown Adipose Stem Cell-Loaded Resilin Elastic Hydrogel Rebuilds Cardiac Function after Myocardial Infarction via Collagen I/III Reorganisation

Irreversible fibrosis following myocardial infarction (MI) stiffens the infarcted myocardium, which remains challenging to restore. This study aimed to investigate whether the injectable RLP12 hydrogel, derived from recombinant resilin protein, could serve as a vehicle for stem cells to enhance the function of the infarcted myocardium. The RLP12 hydrogel was prepared and injected into the myocardium of rats with MI, and brown adipose-derived mesenchymal stem cells (BADSCs) were loaded. The survival and differentiation of BADSCs in vivo were investigated using immunofluorescence one week and four weeks after treatment, respectively. The heart function, MI area, collagen deposition, and microvessel density were further assessed four weeks after treatment through echocardiography, histology, immunohistochemistry, and immunofluorescence. The RLP12 hydrogel was prepared with a shear modulus of 10-15 kPa. Four weeks after transplantation, the RLP12 hydrogel significantly improved cardiac function by increasing microvessel density and reducing infarct area size and collagen deposition in MI rats. Furthermore, the distribution ratio of collagen III to I increased in both the centre and edge areas of the MI, indicating the improved compliance of the infarct heart. Moreover, the RLP12 hydrogel also promoted the survival and differentiation of BADSCs into cardiac troponin T- and α-smooth muscle-positive cells. The RLP12 hydrogel can be utilised as an injectable vehicle of BADSCs for treating MI and regulating collagen I and III expression profiles to improve the mechanical microenvironment of the infarct site, thereby restoring heart function. The study provides novel insights into the mechanical interactions between the hydrogel and the infarct microenvironment.

Insights into the prospects of nanobiomaterials in the treatment of cardiac arrhythmia

Cardiac arrhythmia, a disorder of abnormal electrical activity of the heart that disturbs the rhythm of the heart, thereby affecting its normal function, is one of the leading causes of death from heart disease worldwide and causes millions of deaths each year. Currently, treatments for arrhythmia include drug therapy, radiofrequency ablation, cardiovascular implantable electronic devices (CIEDs), including pacemakers, defibrillators, and cardiac resynchronization therapy (CRT). However, these traditional treatments have several limitations, such as the side effects of medication, the risks of device implantation, and the complications of invasive surgery. Nanotechnology and nanomaterials provide safer, effective and crucial treatments to improve the quality of life of patients with cardiac arrhythmia. The large specific surface area, controlled physical and chemical properties, and good biocompatibility of nanobiomaterials make them promising for a wide range of applications, such as cardiovascular drug delivery, tissue engineering, and the diagnosis and therapeutic treatment of diseases. However, issues related to the genotoxicity, cytotoxicity and immunogenicity of nanomaterials remain and require careful consideration. In this review, we first provide a brief overview of cardiac electrophysiology, arrhythmia and current treatments for arrhythmia and discuss the potential applications of nanobiomaterials before focusing on the promising applications of nanobiomaterials in drug delivery and cardiac tissue repair. An in-depth study of the application of nanobiomaterials is expected to provide safer and more effective therapeutic options for patients with cardiac arrhythmia, thereby improving their quality of life.

Electroactive poly(vinylidene fluoride-trifluoroethylene)/graphene composites for cardiac tissue engineering applications

Electroactive materials are increasingly being used in strategies to regenerate cardiac tissue. These materials, particularly those with electrical conductivity, are used to actively recreate the electromechanical nature of the cardiac tissue. In the present work, we describe a novel combination of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), a highly electroactive polymer, with graphene (G), exhibiting high electrical conductivity. G/P(VDF-TrFE) films have been characterized in terms of topographical, physico-chemical, mechanical, electrical, and thermal properties, and studied the response of cardiomyocytes adhering to them. The results indicate that the crystallinity and the wettability of the composites remain almost unaffected after G incorporation. In turn, surface roughness, Young modulus, and electric properties are higher in G/P(VDF-TrFE). Finally, the composites are highly biocompatible and able to support cardiomyocyte adhesion and proliferation, particularly surface treated ones, demonstrating the suitability of these materials for cardiac tissue engineering applications.

An L-shaped relationship between dietary vitamin K and atherosclerotic cardiovascular disease

BACKGROUND AND AIMS

Few studies link vitamin K intake with incident atherosclerotic cardiovascular disease (ASCVD), and the specific mechanism remains uncertain. We aimed to evaluate the relationship between dietary vitamin K and ASCVD.

METHODS

This study used cross-sectional data from people over 20 years old who took part in the National Health and Nutrition Examination Survey (NHANES) between 2013 and 2018. Vitamin K intake was assessed using a 24-h dietary review. The Patient Medical Conditions Questionnaire was used to assess ASCVD. The stability of the outcomes was evaluated using cubic spline models with restricted parameters and logistic regression, while subgroup analyses were also performed.

RESULTS

There were 14,465 participants, with 9.78% (1415/14,465) who diagnosed with ASCVD. Compared with individuals with lower vitamin K intake Q1 (≤39.0 ug/day), the adjusted OR values for dietary vitamin K intake and ASCVD in Q2 (39.1-70.8 ug/day), Q3 (70.9-131.0 mg/day), and Q4 (≥131.1 ug/day) were 0.88 (95% CI: 0.74-1.04, p = 0.134), 0.77(95% CI: 0.65-0.93, p = 0.005), and 0.78 (95% CI: 0.65-0.95, p = 0.013), respectively. The association between dietary vitamin K intake and ASCVD showed an L-shaped curve (nonlinear, p = 0.006). The OR for ASCVD in participants with vitamin K intake <127.1ug/day was 0.996 (95% CI: 0.993-0.998, p = 0.002).

CONCLUSIONS

The relationship between dietary vitamin K intake and ASCVD was L-shaped curve in US adults, the inflection point was roughly 127.1 ug/day.

Looking both ways: Electroactive biomaterials with bidirectional implications for dynamic cell-material crosstalk

Cells exist in natural, dynamic microenvironmental niches that facilitate biological responses to external physicochemical cues such as mechanical and electrical stimuli. For excitable cells, exogenous electrical cues are of interest due to their ability to stimulate or regulate cellular behavior via cascade signaling involving ion channels, gap junctions, and integrin receptors across the membrane. In recent years, conductive biomaterials have been demonstrated to influence or record these electrosensitive biological processes whereby the primary design criterion is to achieve seamless cell-material integration. As such, currently available bioelectronic materials are predominantly engineered toward achieving high-performing devices while maintaining the ability to recapitulate the local excitable cell/tissue microenvironment. However, such reports rarely address the dynamic signal coupling or exchange that occurs at the biotic-abiotic interface, as well as the distinction between the ionic transport involved in natural biological process and the electronic (or mixed ionic/electronic) conduction commonly responsible for bioelectronic systems. In this review, we highlight current literature reports that offer platforms capable of bidirectional signal exchange at the biotic-abiotic interface with excitable cell types, along with the design criteria for such biomaterials. Furthermore, insights on current materials not yet explored for biointerfacing or bioelectronics that have potential for bidirectional applications are also provided. Finally, we offer perspectives aimed at bringing attention to the coupling of the signals delivered by synthetic material to natural biological conduction mechanisms, areas of improvement regarding characterizing biotic-abiotic crosstalk, as well as the dynamic nature of this exchange, to be taken into consideration for material/device design consideration for next-generation bioelectronic systems.

Conducting polymer scaffolds: a new frontier in bioelectronics and bioengineering

Conducting polymer (CP) scaffolds have emerged as a transformative tool in bioelectronics and bioengineering, advancing the ability to interface with biological systems. Their unique combination of electrical conductivity, tailorability, and biocompatibility surpasses the capabilities of traditional nonconducting scaffolds while granting them access to the realm of bioelectronics. This review examines recent developments in CP scaffolds, focusing on material and device advancements, as well as their interplay with biological systems. We highlight applications for monitoring, tissue stimulation, and drug delivery and discuss perspectives and challenges currently faced for their ultimate translation and clinical implementation.

Advancements in tissue engineering for cardiovascular health: a biomedical engineering perspective

Myocardial infarction (MI) stands as a prominent contributor to global cardiovascular disease (CVD) mortality rates. Acute MI (AMI) can result in the loss of a large number of cardiomyocytes (CMs), which the adult heart struggles to replenish due to its limited regenerative capacity. Consequently, this deficit in CMs often precipitates severe complications such as heart failure (HF), with whole heart transplantation remaining the sole definitive treatment option, albeit constrained by inherent limitations. In response to these challenges, the integration of bio-functional materials within cardiac tissue engineering has emerged as a groundbreaking approach with significant potential for cardiac tissue replacement. Bioengineering strategies entail fortifying or substituting biological tissues through the orchestrated interplay of cells, engineering methodologies, and innovative materials. Biomaterial scaffolds, crucial in this paradigm, provide the essential microenvironment conducive to the assembly of functional cardiac tissue by encapsulating contracting cells. Indeed, the field of cardiac tissue engineering has witnessed remarkable strides, largely owing to the application of biomaterial scaffolds. However, inherent complexities persist, necessitating further exploration and innovation. This review delves into the pivotal role of biomaterial scaffolds in cardiac tissue engineering, shedding light on their utilization, challenges encountered, and promising avenues for future advancement. By critically examining the current landscape, we aim to catalyze progress toward more effective solutions for cardiac tissue regeneration and ultimately, improved outcomes for patients grappling with cardiovascular ailments.

Evaluation of Advanced Nanomaterials for Cancer Diagnosis and Treatment

Cancer is a persistent global disease and a threat to the human species, with numerous cases reported every year. Over recent decades, a steady but slowly increasing mortality rate has been observed. While many attempts have been made using conventional methods alone as a theragnostic strategy, they have yielded very little success. Most of the shortcomings of such conventional methods can be attributed to the high demands of industrial growth and ever-increasing environmental pollution. This requires some high-tech biomedical interventions and other solutions. Thus, researchers have been compelled to explore alternative methods. This has brought much attention to nanotechnology applications, specifically magnetic nanomaterials, as the sole or conjugated theragnostic methods. The exponential growth of nanomaterials with overlapping applications in various fields is due to their potential properties, which depend on the type of synthesis route used. Either top-down or bottom-up strategies synthesize various types of NPs. The top-down only branches out to one method, i.e., physical, and the bottom-up has two methods, chemical and biological syntheses. This review highlights some synthesis techniques, the types of nanoparticle properties each technique produces, and their potential use in the biomedical field, more specifically for cancer. Despite the evident drawbacks, the success achieved in furthering nanoparticle applications to more complex cancer stages and locations is unmatched.

Environmental and Health Impacts of Graphene and Other Two-Dimensional Materials: A Graphene Flagship Perspective

Two-dimensional (2D) materials have attracted tremendous interest ever since the isolation of atomically thin sheets of graphene in 2004 due to the specific and versatile properties of these materials. However, the increasing production and use of 2D materials necessitate a thorough evaluation of the potential impact on human health and the environment. Furthermore, harmonized test protocols are needed with which to assess the safety of 2D materials. The Graphene Flagship project (2013-2023), funded by the European Commission, addressed the identification of the possible hazard of graphene-based materials as well as emerging 2D materials including transition metal dichalcogenides, hexagonal boron nitride, and others. Additionally, so-called green chemistry approaches were explored to achieve the goal of a safe and sustainable production and use of this fascinating family of nanomaterials. The present review provides a compact survey of the findings and the lessons learned in the Graphene Flagship.

One Pot Photomediated Formation of Electrically Conductive Hydrogels

Electrically conductive hydrogels represent an innovative platform for the development of bioelectronic devices. While photolithography technologies have enabled the fabrication of complex architectures with high resolution, photoprinting conductive hydrogels is still a challenging task because the conductive polymer absorbs light which can outcompete photopolymerization of the insulating scaffold. In this study, we introduce an approach to synthesizing conductive hydrogels in one step. Our approach combines the simultaneous photo-cross-linking of a polymeric scaffold and the polymerization of 3,4-ethylene dioxythiophene (EDOT), without additional photocatalysts. This process involves the copolymerization of photo-cross-linkable coumarin-containing monomers with sodium styrenesulfonate to produce a water-soluble poly(styrenesulfonate-co-coumarin acrylate) (P(SS-co-CoumAc)) copolymer. Our findings reveal that optimizing the [SS]:[CoumAc] ratio at 100:5 results in hydrogels with the strain at break up to 16%. This mechanical resilience is coupled with an electronic conductivity of 9.2 S m-1 suitable for wearable electronics. Furthermore, the conductive hydrogels can be photopatterned to achieve micrometer-sized structures with high resolution. The photo-cross-linked hydrogels are used as electrodes to record stable and reliable surface electromyography (sEMG) signals. These novel photo-cross-linkable polymers combined with one-pot PEDOT (poly-EDOT) polymerization open possibilities for rapidly prototyping complex bioelectronic devices and creating custom-designed interfaces between electronics and biological systems.

Nanomaterials-combined methacrylated gelatin hydrogels (GelMA) for cardiac tissue constructs

Among non-communicable diseases, cardiovascular diseases are the most prevalent, accounting for approximately 17 million deaths per year. Despite conventional treatment, cardiac tissue engineering emerges as a potential alternative for the advancement and treatment of these patients, using biomaterials to replace or repair cardiac tissues. Among these materials, gelatin in its methacrylated form (GelMA) is a biodegradable and biocompatible polymer with adjustable biophysical properties. Furthermore, gelatin has the ability to replace and perform collagen-like functions for cell development in vitro. The interest in using GelMA hydrogels combined with nanomaterials is increasingly growing to promote the responsiveness to external stimuli and improve certain properties of these hydrogels by exploring the incorporation of nanomaterials into these hydrogels to serve as electrical signaling conductive elements. This review highlights the applications of electrically conductive nanomaterials associated with GelMA hydrogels for the development of structures for cardiac tissue engineering, by focusing on studies that report the combination of GelMA with nanomaterials, such as gold and carbon derivatives (carbon nanotubes and graphene), in addition to the possibility of applying these materials in 3D tissue engineering, developing new possibilities for cardiac studies.

Advances in nanobased platforms for cardiovascular diseases: Early diagnosis, imaging, treatment, and tissue engineering

Cardiovascular diseases (CVDs) present a significant threat to health, with traditional therapeutics based treatment being hindered by inefficiencies, limited biological effects, and resistance to conventional drug. Addressing these challenges requires advanced approaches for early disease diagnosis and therapy. Nanotechnology and nanomedicine have emerged as promising avenues for personalized CVD diagnosis and treatment through theranostic agents. Nanoparticles serve as nanodevices or nanocarriers, efficiently transporting drugs to injury sites. These nanocarriers offer the potential for precise drug and gene delivery, overcoming issues like bioavailability and solubility. By attaching specific target molecules to nanoparticle surfaces, controlled drug release to targeted areas becomes feasible. In the field of cardiology, nanoplatforms have gained popularity due to their attributes, such as passive or active targeting of cardiac tissues, enhanced sensitivity and specificity, and easy penetration into heart and artery tissues due to their small size. However, concerns persist about the immunogenicity and cytotoxicity of nanomaterials, necessitating careful consideration. Nanoparticles also hold promise for CVD diagnosis and imaging, enabling straightforward diagnostic procedures and real-time tracking during therapy. Nanotechnology has revolutionized cardiovascular imaging, yielding multimodal and multifunctional vehicles that outperform traditional methods. The paper provides an overview of nanomaterial delivery routes, targeting techniques, and recent advances in treating, diagnosing, and engineering tissues for CVDs. It also discusses the future potential of nanomaterials in CVDs, including theranostics, aiming to enhance cardiovascular treatment in clinical practice. Ultimately, refining nanocarriers and delivery methods has the potential to enhance treatment effectiveness, minimize side effects, and improve patients' well-being and outcomes.

Cyclical endometrial repair and regeneration: Molecular mechanisms, diseases, and therapeutic interventions

The endometrium is a unique human tissue with an extraordinary ability to undergo a hormone-regulated cycle encompassing shedding, bleeding, scarless repair, and regeneration throughout the female reproductive cycle. The cyclical repair and regeneration of the endometrium manifest as changes in endometrial epithelialization, glandular regeneration, and vascularization. The mechanisms encompass inflammation, coagulation, and fibrinolytic system balance. However, specific conditions such as endometriosis or TCRA treatment can disrupt the process of cyclical endometrial repair and regeneration. There is uncertainty about traditional clinical treatments' efficacy and side effects, and finding new therapeutic interventions is essential. Researchers have made substantial progress in the perspective of regenerative medicine toward maintaining cyclical endometrial repair and regeneration in recent years. Such progress encompasses the integration of biomaterials, tissue-engineered scaffolds, stem cell therapies, and 3D printing. This review analyzes the mechanisms, diseases, and interventions associated with cyclical endometrial repair and regeneration. The review discusses the advantages and disadvantages of the regenerative interventions currently employed in clinical practice. Additionally, it highlights the significant advantages of regenerative medicine in this domain. Finally, we review stem cells and biologics among the available interventions in regenerative medicine, providing insights into future therapeutic strategies.

Designing Biomimetic Conductive Gelatin-Chitosan-Carbon Black Nanocomposite Hydrogels for Tissue Engineering

Conductive nanocomposites play a significant role in tissue engineering by providing a platform to support cell growth, tissue regeneration, and electrical stimulation. In the present study, a set of electroconductive nanocomposite hydrogels based on gelatin (G), chitosan (CH), and conductive carbon black (CB) was synthesized with the aim of developing novel biomaterials for tissue regeneration application. The incorporation of conductive carbon black (10, 15 and 20 wt.%) significantly improved electrical conductivity and enhanced mechanical properties with the increased CB content. We employed an oversimplified unidirectional freezing technique to impart anisotropic morphology with interconnected porous architecture. An investigation into whether any anisotropic morphology affects the mechanical properties of hydrogel was conducted by performing compression and cyclic compression tests in each direction parallel and perpendicular to macroporous channels. Interestingly, the nanocomposite with 10% CB produced both anisotropic morphology and mechanical properties, whereas anisotropic pore morphology diminished at higher CB concentrations (15 and 20%), imparting a denser texture. Collectively, the nanocomposite hydrogels showed great structural stability as well as good mechanical stability and reversibility. Under repeated compressive cyclic at 50% deformation, the nanocomposite hydrogels showed preconditioning, characteristic hysteresis, nonlinear elasticity, and toughness. Overall, the collective mechanical behavior resembled the mechanics of soft tissues. The electrical impedance associated with the hydrogels was studied in terms of the magnitude and phase angle in dry and wet conditions. The electrical properties of the nanocomposite hydrogels conducted in wet conditions, which is more physiologically relevant, showed a decreasing magnitude with increased CB concentrations, with a resistive-like behavior in the range 1 kHz-1 MHz and a capacitive-like behavior for frequencies <1 kHz and >1 MHz. Overall, the impedance of the nanocomposite hydrogels decreased with increased CB concentrations. Together, these nanocomposite hydrogels are compositionally, morphologically, mechanically, and electrically similar to native ECMs of many tissues. These gelatin-chitosan-carbon black nanocomposite hydrogels show great promise for use as conducting substrates for the growth of electro-responsive cells in tissue engineering.

Influence of GO-Antisense miRNA-21 on the Expression of Selected Cytokines at Glioblastoma Cell Lines

Introduction

Graphene oxide (GO) is a single layer of carbon atoms with unique properties, which are beneficial due to its surface functionalisation by miRNA. miRNAs are a non-coding small form of RNA that suppress the expression of protein-coding genes by translational repression or degradation of messenger RNA. Antisense miRNA-21 is very promising for future investigation in cancer therapy. This study aimed to detect cytokine expression levels after the administration of GO-antisense miRNA-21 into U87, U118, U251 and T98 glioma cell lines.

Methods

U87, U118, U251 and T98 glioma cell line were investigated in term of viability, human cytokine expression level at protein and genes after treatment with GO, GO-antisense miRNA-21 and antisense miRNA-21. The delivery of antisense miRNA-21 into the glioma cell at in vitro investigation were conducted by GO based transfection and electroporation.

Results

The results of the protein microarray and gene expression profile showed that complexes of GO-antisense miRNA-21 modified the metallopeptidase inhibitor 2 (TIMP-2), interleukin-6 (IL-6), interleukin 8 (IL-8), intercellular adhesion molecule 1 (ICAM-1), and monocyte chemoattractant protein-1 (MCP-1) expression level compared to transfection by electroporation of antisense miRNA-21 at investigated glioblastoma cell lines. The TIMP-2 protein and gene expression level was upregulated after antisense miRNA-21 delivery by GO complex into U87, U251 and T98 glioblastoma cell lines comparing to the non-treated control group. The downregulation at protein expression level of ICAM - 1 was observed at U87, U118, U251 and T98 glioma cell lines. Moreover, the IL-8 expression level at mRNA for genes and protein was decreased significantly after delivery the antisense-miRNA-21 by GO compared to electroporation as a transfection method.

Discussion

This work demonstrated that the graphene oxide complexes with antisense miRNA-21 can effectively modulate the cytokine mRNA and protein expression level at U87, U118, U251 and T98 glioma cell lines.

Multi-material electrospinning: from methods to biomedical applications

Electrospinning as a versatile, simple, and cost-effective method to engineer a variety of micro or nanofibrous materials, has contributed to significant developments in the biomedical field. However, the traditional electrospinning of single material only can produce homogeneous fibrous assemblies with limited functional properties, which oftentimes fails to meet the ever-increasing requirements of biomedical applications. Thus, multi-material electrospinning referring to engineering two or more kinds of materials, has been recently developed to enable the fabrication of diversified complex fibrous structures with advanced performance for greatly promoting biomedical development. This review firstly gives an overview of multi-material electrospinning modalities, with a highlight on their features and accessibility for constructing different complex fibrous structures. A perspective of how multi-material electrospinning opens up new opportunities for specific biomedical applications, i.e., tissue engineering and drug delivery, is also offered.

Orange Pomace-Derived Fluorescent Carbon Quantum Dots: Detection of Dual Analytes in the Nanomolar Range

Green-emissive carbon quantum dots (CQDs) with exclusive chemosensing aspects were synthesized from orange pomace as a biomass-based precursor via a facile microwave method without using any chemicals. The synthesis of highly fluorescent CQDs with inherent nitrogen was confirmed through X-ray diffraction, X-ray photoelectron, Fourier transform infrared, Raman, and transmission electron microscopic techniques. The average size of the synthesized CQDs was found to be 7.5 nm. These fabricated CQDs displayed excellent photostability, water solubility, and outstanding fluorescent quantum yield, i.e., 54.26%. The synthesized CQDs showed promising results for the detection of Cr⁶⁺ ions and 4-nitrophenol (4-NP). The sensitivity of CQDs toward Cr⁶⁺ and 4-NP was found up to the nanomolar range with the limit of detection values of 59.6 and 14 nM, respectively. Several analytical performances were thoroughly studied for high precision of dual analytes of the proposed nanosensor. Various photophysical parameters of CQDs (quenching efficiency, binding constant, etc.) were analyzed in the presence of dual analytes to gain more insights into the sensing mechanism. The synthesized CQDs exhibited fluorescence quenching toward incrementing the quencher concentration, which was rationalized by the inner filter effect through time-correlated single-photon counting measurements. The CQDs fabricated in the current work exhibited a lower detection limit and a wide linear range through the simple, eco-friendly, and rapid detection of Cr⁶⁺ and 4-NP ions. To evaluate the feasibility of the detection approach, real sample analysis was conducted, demonstrating satisfactory recovery rates and relative standard deviations toward the developed probes. This research paves the way for developing CQDs with superior characteristics utilizing orange pomace (biowaste precursor).

Hole-Transport Material Engineering in Highly Durable Carbon-Based Perovskite Photovoltaic Devices

Despite the fast-developing momentum of perovskite solar cells (PSCs) toward flexible roll-to-roll solar energy harvesting panels, their long-term stability remains to be the challenging obstacle in terms of moisture, light sensitivity, and thermal stress. Compositional engineering including less usage of volatile methylammonium bromide (MABr) and incorporating more formamidinium iodide (FAI) promises more phase stability. In this work, an embedded carbon cloth in carbon paste is utilized as the back contact in PSCs (having optimized perovskite composition), resulting in a high power conversion efficiency (PCE) of 15.4%, and the as-fabricated devices retain 60% of the initial PCE after more than 180 h (at the experiment temperature of 85 °C and under 40% relative humidity). These results are from devices without any encapsulation or light soaking pre-treatments, whereas Au-based PSCs retain 45% of the initial PCE at the same conditions with rapid degradation. In addition, the long-term device stability results reveal that poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) is a more stable polymeric hole-transport material (HTM) at the 85 °C thermal stress than the copper thiocyanate (CuSCN) inorganic HTM for carbon-based devices. These results pave the way toward modifying additive-free and polymeric HTM for scalable carbon-based PSCs.

Stability and Thrombogenicity Analysis of Collagen/Carbon Nanotube Nanocomposite Coatings Using a Reversible Microfluidic Device

Currently, the development of stable and antithrombogenic coatings for cardiovascular implants is socially important. This is especially important for coatings exposed to high shear stress from flowing blood, such as those on ventricular assist devices. A method of layer-by-layer formation of nanocomposite coatings based on multi-walled carbon nanotubes (MWCNT) in a collagen matrix is proposed. A reversible microfluidic device with a wide range of flow shear stresses has been developed for hemodynamic experiments. The dependence of the resistance on the presence of a cross-linking agent for collagen chains in the composition of the coating was demonstrated. Optical profilometry determined that collagen/c-MWCNT and collagen/c-MWCNT/glutaraldehyde coatings obtained sufficiently high resistance to high shear stress flow. However, the collagen/c-MWCNT/glutaraldehyde coating was almost twice as resistant to a phosphate-buffered solution flow. A reversible microfluidic device made it possible to assess the level of thrombogenicity of the coatings by the level of blood albumin protein adhesion to the coatings. Raman spectroscopy demonstrated that the adhesion of albumin to collagen/c-MWCNT and collagen/c-MWCNT/glutaraldehyde coatings is 1.7 and 1.4 times lower than the adhesion of protein to a titanium surface, widely used for ventricular assist devices. Scanning electron microscopy and energy dispersive spectroscopy determined that blood protein was least detected on the collagen/c-MWCNT coating, which contained no cross-linking agent, including in comparison with the titanium surface. Thus, a reversible microfluidic device is suitable for preliminary testing of the resistance and thrombogenicity of various coatings and membranes, and nanocomposite coatings based on collagen and c-MWCNT are suitable candidates for the development of cardiovascular devices.

Applications of Stimuli-Responsive Hydrogels in Bone and Cartilage Regeneration

Bone and cartilage regeneration is an area of tremendous interest and need in health care. Tissue engineering is a potential strategy for repairing and regenerating bone and cartilage defects. Hydrogels are among the most attractive biomaterials in bone and cartilage tissue engineering, mainly due to their moderate biocompatibility, hydrophilicity, and 3D network structure. Stimuli-responsive hydrogels have been a hot topic in recent decades. They can respond to external or internal stimulation and are used in the controlled delivery of drugs and tissue engineering. This review summarizes current progress in the use of stimuli-responsive hydrogels in bone and cartilage regeneration. The challenges, disadvantages, and future applications of stimuli-responsive hydrogels are briefly described.

3D Graphene Oxide-Polyethylenimine Scaffolds for Cardiac Tissue Engineering

The development of novel three-dimensional (3D) nanomaterials combining high biocompatibility, precise mechanical characteristics, electrical conductivity, and controlled pore size to enable cell and nutrient permeation is highly sought after for cardiac tissue engineering applications including repair of damaged heart tissues following myocardial infarction and heart failure. Such unique characteristics can collectively be found in hybrid, highly porous tridimensional scaffolds based on chemically functionalized graphene oxide (GO). By exploiting the rich reactivity of the GO's basal epoxydic and edge carboxylate moieties when interacting, respectively, with NH2 and NH3+ groups of linear polyethylenimines (PEIs), 3D architectures with variable thickness and porosity can be manufactured, making use of the layer-by-layer technique through the subsequent dipping in GO and PEI aqueous solutions, thereby attaining enhanced compositional and structural control. The elasticity modulus of the hybrid material is found to depend on scaffold's thickness, with the lowest value of 13 GPa obtained in samples containing the highest number of alternating layers. Thanks to the amino-rich composition of the hybrid and the established biocompatibility of GO, the scaffolds do not exhibit cytotoxicity; they promote cardiac muscle HL-1 cell adhesion and growth without interfering with the cell morphology and increasing cardiac markers such as Connexin-43 and Nkx 2.5. Our novel strategy for scaffold preparation thus overcomes the drawbacks associated with the limited processability of pristine graphene and low GO conductivity, and it enables the production of biocompatible 3D GO scaffolds covalently functionalized with amino-based spacers, which is advantageous for cardiac tissue engineering applications. In particular, they displayed a significant increase in the number of gap junctions compared to HL-1 cultured on CTRL substrates, which render them key components for repairing damaged heart tissues as well as being used for 3D in vitro cardiac modeling investigations.