Electrically stimulated cell migration and its contribution to wound healing

Synthesis and analysis of multifunctional graphene oxide/Ag2O-PVA/chitosan hybrid polymeric composite for wound healing applications

The requirement for accurate treatments for skin diseases and wounds, generated a rising interest towards multifunctional polymer composites, that are capable of mimicking the natural compositions in human body. Also, electroactive composite films disseminate endogenous electrical stimulations that encourage cell migration and its proliferation at wound site, proposing greater opportunities in upgrading the conventional wound patches. In this work, the composite film made of graphene oxide, Ag2O, PVA and chitosan were developed for wound healing applications, by the solution casting method. The even dispersibility of nanofiller in polymeric matrix was validated from the physicochemical analyses. The increment in roughness of the composite film surface was noted from AFM images. The thermal stability and porous nature of the polymer composite were also verified. A conductivity value of 0.16 × 10-4 Scm-1 was obtained for the film. From MTT assay, it was noted that the films were non-cytotoxic and supported cell adhesion along with cell proliferation of macrophage (RAW 264.7) cells. Moreover, the composite film also demonstrated non-hemolytic activity of <2 %, as well as excellent antibacterial activity towards E. coli and S. aureus. Thus, the obtained results validated that the prepared composite film could be chosen as an innovative candidate for developing state-of-the-art wound dressings.

Multifunctional Bone Regeneration Membrane with Flexibility, Electrical Stimulation Activity and Osteoinductive Activity

The use of membrane-based guided bone regeneration techniques has great potential for single-stage reconstruction of critical-sized bone defects. Here, a multifunctional bone regeneration membrane combining flexible elasticity, electrical stimulation (ES) and osteoinductive activity is developed by in situ doping of MXene 2D nanomaterials with conductive functionality and β-TCP particles into a Poly(lactic acid-carbonate (PDT) composite nano-absorbable membrane (P/T/MXene) via electrostatic spinning technique. The composite membrane has good feasibility due to its temperature sensitivity, elastic memory capacity, coordinated degradation profile and easy preparation process. In vitro experiments showed the P/T/MXene membrane effectively promoted the recruitment and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) under ES and enhanced the angiogenic capacity of endothelial cells, which synergistically promoted bone regeneration through neovascularization. In addition, an in vivo rat model of cranial bone defects further confirmed the bone regeneration efficacy of the P/T/MXene membrane. In conclusion, the developed P/T/MXene membrane can effectively promote bone regeneration through their synergistic multifunctional effects, suggesting the membranes have great potential for guiding tissue regeneration and providing guidance for the biomaterials design.

A Rheological Study on the Effect of Tethering Pro- and Anti-Inflammatory Cytokines into Hydrogels on Human Mesenchymal Stem Cell Migration, Degradation, and Morphology

Polymer-peptide hydrogels are being designed as implantable materials that deliver human mesenchymal stem cells (hMSCs) to treat wounds. Most wounds can progress through the healing process without intervention. During the normal healing process, cytokines are released from the wound to create a concentration gradient, which causes directed cell migration from the native niche to the wound site. Our work takes inspiration from this process and uniformly tethers cytokines into the scaffold to measure changes in cell-mediated degradation and motility. This is the first step in designing cytokine concentration gradients into the material to direct cell migration. We measure changes in rheological properties, encapsulated cell-mediated pericellular degradation and migration in a hydrogel scaffold with covalently tethered cytokines, either tumor necrosis factor-α (TNF-α) or transforming growth factor-β (TGF-β). TNF-α is expressed in early stages of wound healing causing an inflammatory response. TGF-β is released in later stages of wound healing causing an anti-inflammatory response in the surrounding tissue. Both cytokines cause directed cell migration. We measure no statistically significant difference in modulus or the critical relaxation exponent when tethering either cytokine in the polymeric network without encapsulated hMSCs. This indicates that the scaffold structure and rheology is unchanged by the addition of tethered cytokines. Increases in hMSC motility, morphology and cell-mediated degradation are measured using a combination of multiple particle tracking microrheology (MPT) and live-cell imaging in hydrogels with tethered cytokines. We measure that tethering TNF-α into the hydrogel increases cellular remodeling on earlier days postencapsulation and tethering TGF-β into the scaffold increases cellular remodeling on later days. We measure tethering either TGF-β or TNF-α enhances cell stretching and, subsequently, migration. This work provides rheological characterization that can be used to design new materials that present chemical cues in the pericellular region to direct cell migration.

A quadriphasic mechanical model of the human dermis

The present study investigates the multiphasic nature of the mechanical behavior of human dermis. Motivated by experimental observations and by consideration of its composition, a quadriphasic model of the dermis is proposed, distinguishing solid matrix components, interstitial fluid and charged constituents moving within the fluid, i.e., anions and cations. Compression and tensile experiments with and without change of osmolarity of the bath are performed to characterize the chemo-mechanical coupling in the dermis. Model parameters are determined through inverse analysis. The computations predict a dominant role of the permeability in the determination of the temporal evolution of the mechanical response of the tissue. In line with the previous studies on other tissues, the analysis shows that an ideal model based on Donnan's equilibrium overestimates the osmotic pressure in skin for the case of very dilute solutions. The quadriphasic model is applied to predict changes in dermal cell environment and therefore alterations in what is called the "mechanome," associated with skin stretch. The simulations indicate that skin deformation causes a variation in several local variables, including in particular the electric field associated with a deformation-induced non-homogeneous distribution of fixed charges.

Bioelectret Materials and Their Bioelectric Effects for Tissue Repair: A Review

Biophysical and clinical medical studies have confirmed that biological tissue lesions and trauma are related to the damage of an intrinsic electret (i.e., endogenous electric field), such as wound healing, embryonic development, the occurrence of various diseases, immune regulation, tissue regeneration, and cancer metastasis. As exogenous electrical signals, such as conductivity, piezoelectricity, ferroelectricity, and pyroelectricity, bioelectroactives can regulate the endogenous electric field, thus controlling the function of cells and promoting the repair and regeneration of tissues. Materials, once polarized, can harness their inherent polarized static electric fields to generate an electric field through direct stimulation or indirect interactions facilitated by physical signals, such as friction, ultrasound, or mechanical stimulation. The interaction with the biological microenvironment allows for the regulation and compensation of polarized electric signals in damaged tissue microenvironments, leading to tissue regeneration and repair. The technique shows great promise for applications in the field of tissue regeneration. In this paper, the generation and change of the endogenous electric field and the regulation of exogenous electroactive substances are expounded, and the latest research progress of the electret and its biological effects in the field of tissue repair include bone repair, nerve repair, drug penetration promotion, wound healing, etc. Finally, the opportunities and challenges of electret materials in tissue repair were summarized. Exploring the research and development of new polarized materials and the mechanism of regulating endogenous electric field changes may provide new insights and innovative methods for tissue repair and disease treatment in biological applications.

From electricity to vitality: the emerging use of piezoelectric materials in tissue regeneration

The unique ability of piezoelectric materials to generate electricity spontaneously has attracted widespread interest in the medical field. In addition to the ability to convert mechanical stress into electrical energy, piezoelectric materials offer the advantages of high sensitivity, stability, accuracy and low power consumption. Because of these characteristics, they are widely applied in devices such as sensors, controllers and actuators. However, piezoelectric materials also show great potential for the medical manufacturing of artificial organs and for tissue regeneration and repair applications. For example, the use of piezoelectric materials in cochlear implants, cardiac pacemakers and other equipment may help to restore body function. Moreover, recent studies have shown that electrical signals play key roles in promoting tissue regeneration. In this context, the application of electrical signals generated by piezoelectric materials in processes such as bone healing, nerve regeneration and skin repair has become a prospective strategy. By mimicking the natural bioelectrical environment, piezoelectric materials can stimulate cell proliferation, differentiation and connection, thereby accelerating the process of self-repair in the body. However, many challenges remain to be overcome before these concepts can be applied in clinical practice, including material selection, biocompatibility and equipment design. On the basis of the principle of electrical signal regulation, this article reviews the definition, mechanism of action, classification, preparation and current biomedical applications of piezoelectric materials and discusses opportunities and challenges for their future clinical translation.

Progress on Electro-Enhancement of Cell Manufacturing

With the long persistence of complex, chronic diseases in society, there is increasing motivation to develop cells as living medicine to treat diseases ranging from cancer to wounds. While cell therapies can significantly impact healthcare, the shortage of starter cells meant that considerable raw materials must be channeled solely for cell expansion, leading to expensive products with long manufacturing time which can prevent accessibility by patients who either cannot afford the treatment or have highly aggressive diseases and cannot wait that long. Over the last three decades, there has been increasing knowledge on the effects of electrical modulation on proliferation, but to the best of the knowledge, none of these studies went beyond how electro-control of cell proliferation may be extended to enhance industrial scale cell manufacturing. Here, this review is started by discussing the importance of maximizing cell yield during manufacturing before comparing strategies spanning biomolecular/chemical/physical to modulate cell proliferation. Next, the authors describe how factors governing invasive and non-invasive electrical stimulation (ES) including capacitive coupling electric field may be modified to boost cell manufacturing. This review concludes by describing what needs to be urgently performed to bridge the gap between academic investigation of ES to industrial applications.

Identification of the Wound Healing Activity Peptidome of Edible Bird's Nest Protein Hydrolysate and the In Silico Evaluation of Its Transport and Absorption Potential in Skin

In this study, edible bird's nest (EBN) was proven to be a suitable source of bioactive peptides via enzymatic hydrolysis. The ultrafiltration component of the EBN peptides (EBNPs, Mw < 3 000 Da) could be responsible for moderate moisture retention and filaggrin synthesis. It was found that EBNP had a great capacity to protect HaCaT keratinocytes from DNA damage caused by UVB-irradiation and enhance wound healing by increasing the migratory and proliferative potential of cells. Furthermore, the external application of EBNP could effectively repair high glycolic acid concentration-induced skin burns in mice. A total of 1 188 peptides, predominantly the hydrophobic amino acids (e.g., Leu, Val, Tyr, Phe), were identified in the EBNP by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Molecular docking showed that hydrophobic tripeptides from EBNP had a good binding affinity to proton-dependent oligopeptide transporter PepT1. Our data indicated that the hydrophobic amino acid-rich EBNP plays an important role in skin wound healing.

Bioelectric medicine: unveiling the therapeutic potential of micro-current stimulation

Bioelectric medicine (BEM) refers to the use of electrical signals to modulate the electrical activity of cells and tissues in the body for therapeutic purposes. In this review, we particularly focused on the microcurrent stimulation (MCS), because, this can take place at the cellular level with sub-sensory application unlike other stimuli. These extremely low-level currents mimic the body's natural electrical activity and are believed to promote various physiological processes. To date, MCS has limited use in the field of BEM with applications in several therapeutic purposes. However, recent studies provide hopeful signs that MCS is more scalable and widely applicable than what has been used so far. Therefore, this review delves into the landscape of MCS, shedding light on the multifaceted applications and untapped potential of MCS in the realm of healthcare. Particularly, we summarized the hierarchical mediation from cell to whole body responses by MCS including its physiological applications. Our final objective of this review is to contribute to the growing body of literature that unveils the captivating potential of BEM, with MCS poised at the intersection of technological innovation and the intricacies of the human body.

External Stimuli-Responsive Strategies for Surface Modification of Orthopedic Implants: Killing Bacteria and Enhancing Osteogenesis

Bacterial infection and insufficient osteogenic activity are the main causes of orthopedic implant failure. Conventional surface modification methods are difficult to meet the requirements for long-term implant placement. In order to better regulate the function of implant surfaces, especially to improve both the antibacterial and osteogenic activity, external stimuli-responsive (ESR) strategies have been employed for the surface modification of orthopedic implants. External stimuli act as "smart switches" to regulate the surface interactions with bacteria and cells. The balance between antibacterial and osteogenic capabilities of implant surfaces can be achieved through these specific ESR manifestations, including temperature changes, reactive oxygen species production, controlled release of bioactive molecules, controlled release of functional ions, etc. This Review summarizes the recent progress on different ESR strategies (based on light, ultrasound, electric, and magnetic fields) that can effectively balance antibacterial performance and osteogenic capability of orthopedic implants. Furthermore, the current limitations and challenges of ESR strategies for surface modification of orthopedic implants as well as future development direction are also discussed.

Wearable Magnetoelectric Stimulation for Chronic Wound Healing by Electrospun CoFe2O4@CTAB/PVDF Dressings

Magnetoelectric stimulation is a promising therapy for various disorders due to its high efficacy and safety. To explore its potential in chronic skin wound treatment, we developed a magnetoelectric dressing, CFO@CTAB/PVDF (CCP), by electrospinning cetyltrimethylammonium bromide-modified CoFe2O4 (CFO) particles with polyvinylidene fluoride. Cetyltrimethylammonium bromide (CTAB) serves as a dispersion surfactant for CFO, with its quaternary ammonium cations imparting antibacterial and hydrophilic properties to the dressing. Electrospinning polarizes polyvinylidene fluoride (PVDF) molecules and forms a fibrous membrane with flexibility and breathability. With a wearable electromagnetic induction device, a dynamic magnetic field is established to induce magnetostrictive deformation of CFO nanoparticles. Consequently, a piezoelectric potential is generated on the surface of PVDF nanofibers to enhance the endogenous electrical field in the wound, achieving a cascade coupling of electric-magnetic-mechanical-electric effects. Bacteria and cell cultures show that 2% CTAB effectively balances antibacterial property and fibroblast activity. Under dynamic magnetoelectric stimulation, the CCP dressing demonstrates significant upregulation of TGF-β, FGF, and VEGF, promoting L929 cell adhesion and proliferation. Moreover, it facilitates the healing of diabetic rat skin wounds infected with Staphylococcus aureus within 2 weeks. Histological and molecular biology evaluations confirm the anti-inflammatory effect of CTAB and the accelerated formation of collagen and vessel by electrical stimulation. This work provides insights into the application of magnetoelectric stimulation in the healing of chronic wounds.

Piezoelectric dressings for advanced wound healing

The treatment of chronic refractory wounds poses significant challenges and threats to both human society and the economy. Existing research studies demonstrate that electrical stimulation fosters cell proliferation and migration and promotes the production of cytokines that expedites the wound healing process. Presently, clinical settings utilize electrical stimulation devices for wound treatment, but these devices often present issues such as limited portability and the necessity for frequent recharging. A cutting-edge wound dressing employing the piezoelectric effect could transform mechanical energy into electrical energy, thereby providing continuous electrical stimulation and accelerating wound healing, effectively addressing these concerns. This review primarily reviews the selection of piezoelectric materials and their application in wound dressing design, offering a succinct overview of these materials and their underlying mechanisms. This study also provides a perspective on the current limitations of piezoelectric wound dressings and the future development of multifunctional dressings harnessing the piezoelectric effect.

Paxillin/HDAC6 regulates microtubule acetylation to promote directional migration of keratinocytes driven by electric fields

Endogenous electric fields (EFs) have been demonstrated to facilitate wound healing by directing the migration of epidermal cells. Despite the identification of numerous molecules and signaling pathways that are crucial for the directional migration of keratinocytes under EFs, the underlying molecular mechanisms remain undefined. Previous studies have indicated that microtubule (MT) acetylation is linked to cell migration, while Paxillin exerts a significant influence on cell motility. Therefore, we postulated that Paxillin could enhance EF-induced directional migration of keratinocytes by modulating MT acetylation. In the present study, we observed that EFs (200 mV/mm) induced migration of human immortalized epidermal cells (HaCaT) towards the anode, while upregulating Paxillin, downregulating HDAC6, and increasing the level of microtubule acetylation. Our findings suggested that Paxillin plays a pivotal role in inhibiting HDAC6-mediated microtubule acetylation during directional migration under EF regulation. Conversely, downregulation of Paxillin decreased microtubule acetylation and electrotaxis of epidermal cells by promoting HDAC6 expression, and this effect could be reversed by the addition of tubacin, an HDAC6-specific inhibitor. Furthermore, we observed that EFs also mediated the polarization of Paxillin and acetylated α-tubulin, which is critical for directional migration. In conclusion, our study revealed that MT acetylation in EF-guided keratinocyte migration is regulated by the Paxillin/HDAC6 signaling pathway, providing a novel theoretical foundation for the molecular mechanism of EF-guided directional migration of keratinocytes.

Excite the unexcitable: engineering cells and redox signaling for targeted bioelectronic control

The ever-growing influence of technology in our lives has led to an increasing interest in the development of smart electronic devices to interrogate and control biological systems. Recently, redox-mediated electrogenetics introduced a novel avenue that enables direct bioelectronic control at the genetic level. In this review, we discuss recent advances in methodologies for bioelectronic control, ranging from electrical stimulation to engineering efforts that allow traditionally unexcitable cells to be electrically 'programmable.' Alongside ion-transport signaling, we suggest redox as a route for rational engineering because it is a native form of electronic communication in biology. Using redox as a common language allows the interfacing of electronics and biology. This newfound connection opens a gateway of possibilities for next-generation bioelectronic tools.

Conductive Hydrogel Scaffolds for the 3D Localization and Orientation of Fibroblasts

Dermal wounds and their healing are a collection of complex, multistep processes which are poorly recapitulated by existing 2D in vitro platforms. Biomaterial scaffolds that support the 3D growth of cell cultures can better resemble the native dermal environment, while bioelectronics has been used as a tool to modulate cell proliferation, differentiation, and migration. A porous conductive hydrogel scaffold which mimics the properties of dermis, while promoting the viability and growth of fibroblasts is described. As these scaffolds are also electrically conductive, the application of exogenous electrical stimulation directs the migration of cells across and/or through the material. The mechanical properties of the scaffold, as well as the amplitude and/or duration of the electrical pulses, are independently tunable and further influence the resulting fibroblast networks. This biomaterial platform may enable better recapitulation of wound healing and can be utilized to develop and screen therapeutic interventions.

Review of Piezoelectrical Materials Potentially Useful for Peripheral Nerve Repair

It has increasingly been recognized that electrical currents play a pivotal role in cell migration and tissue repair, in a process named "galvanotaxis". In this review, we summarize the current evidence supporting the potential benefits of electric stimulation (ES) in the physiology of peripheral nerve repair (PNR). Moreover, we discuss the potential of piezoelectric materials in this context. The use of these materials has deserved great attention, as the movement of the body or of the external environment can be used to power internally the electrical properties of devices used for providing ES or acting as sensory receptors in artificial skin (e-skin). The fact that organic materials sustain spontaneous degradation inside the body means their piezoelectric effect is limited in duration. In the case of PNR, this is not necessarily problematic, as ES is only required during the regeneration period. Arguably, piezoelectric materials have the potential to revolutionize PNR with new biomedical devices that range from scaffolds and nerve-guiding conduits to sensory or efferent components of e-skin. However, much remains to be learned regarding piezoelectric materials, their use in manufacturing of biomedical devices, and their sterilization process, to fine-tune their safe, effective, and predictable in vivo application.

A Self-Powered Hydrogel/Nanogenerator System Accelerates Wound Healing by Electricity-Triggered On-Demand Phosphatase and Tensin Homologue (PTEN) Inhibition

Electrical stimulation therapy (EST) has been established as an effective strategy to accelerate wound healing by stimulating cell proliferation and migration, ultimately promoting re-epithelialization and vascularization, two key processes that significantly influence the rate of wound healing. Phosphatase and tensin homologue (PTEN), a widely expressed protein in somatic cells, works as a "brake" regulating cell differentiation, proliferation, and migration. Given that this "brake" also works in cell electrical responses, there is a hypothesis that PTEN inhibition may amplify the efficacy of EST in wound treatment. However, long-term inhibition of PTEN may result in DNA damage and reduce DNA repair, which poses a significant challenge to the safe use of PTEN inhibitors. To address this issue, we developed a system that combines PTEN inhibitor loaded electro-responsive hydrogel (BPV@PCP) with a wearable direct current pulse piezoelectric nanogenerator (PENG). The PENG converts the rat's motions into electric fields that synchronously charge the wound edge tissue and BPV@PCP. Electric field intensity was lower when the rat was quiet or anesthetized, which is insufficient to trigger an effective PTEN inhibitor release. However, when the rat was in action, the electric field intensity exceeded 625 mV/mm, resulting in a rapid drug release. This on-demand PTEN inhibition accelerated wound healing by amplifying cell electric responsiveness while avoiding negative effects associated with continuous overinhibition of PTEN. Notably, this system improves vascularization not only by improving endothelial cell electric responsiveness but also through the paracrine pathway, in which electrical stimulation and PTEN inhibition synergically promote VEGF secretion.

Enhanced Cell Viability and Migration of Primary Bovine Annular Fibrosus Fibroblast-like Cells Induced by Microsecond Pulsed Electric Field Exposure

This study is the first to report the enhancement of cell migration and proliferation induced by in vitro microsecond pulsed electric field (μsPEF) exposure of primary bovine annulus fibrosus (AF) fibroblast-like cells. AF primary cells isolated from fresh bovine intervertebral disks (IVDs) are exposed to 10 and 100 μsPEFs with different numbers of pulses and applied electric field strengths. The results indicate that 10 μs-duration pulses induce reversible electroporation, while 100 μs pulses induce irreversible electroporation of the cells. Additionally, μsPEF exposure increased AF cell proliferation up to 150% while increasing the average migration speed by 0.08 μm/min over 24 h. The findings suggest that the effects of PEF exposure on cells are multifactorial-depending on the duration, intensity, and number of pulses used in the stimulation. This highlights the importance of optimizing the μsPEF parameters for specific cell types and applications. For instance, if the goal is to induce cell death for cancer treatment, then high numbers of pulses can be used to maximize the lethal effects. On the other hand, if the goal is to enhance cell proliferation, a combination of the number of pulses and the applied electric field strength can be tuned to achieve the desired outcome. The information gleaned from this study can be applied in the future to in vitro cell culture expansion and tissue regeneration.

Modern Approaches in Wounds Management

Wound management represents a well-known continuous challenge and concern of the global healthcare systems worldwide. The challenge is on the one hand related to the accurate diagnosis, and on the other hand to establishing an effective treatment plan and choosing appropriate wound care products in order to maximize the healing outcome and minimize the financial cost. The market of wound dressings is a dynamic field which grows and evolves continuously as a result of extensive research on developing versatile formulations with innovative properties. Hydrogels are one of the most attractive wound care products which, in many aspects, are considered ideal for wound treatment and are widely exploited for extension of their advantages in healing process. Smart hydrogels (SHs) offer the opportunities of the modulation physico-chemical properties of hydrogels in response to external stimuli (light, pressure, pH variations, magnetic/electric field, etc.) in order to achieve innovative behavior of their three-dimensional matrix (gel-sol transitions, self-healing and self-adapting abilities, controlled release of drugs). The SHs response to different triggers depends on their composition, cross-linking method, and manufacturing process approach. Both native or functionalized natural and synthetic polymers may be used to develop stimuli-responsive matrices, while the mandatory characteristics of hydrogels (biocompatibility, water permeability, bioadhesion) are preserved. In this review, we briefly present the physiopathology and healing mechanisms of chronic wounds, as well as current therapeutic approaches. The rational of using traditional hydrogels and SHs in wound healing, as well as the current research directions for developing SHs with innovative features, are addressed and discussed along with their limitations and perspectives in industrial-scale manufacturing.

Filler-Enhanced Piezoelectricity of Poly-L-Lactide and Its Use as a Functional Ultrasound-Activated Biomaterial

Poly-L-lactide (PLLA) offers a unique possibility for processing into biocompatible, biodegradable, and implantable piezoelectric structures. With such properties, PLLA has potential to be used as an advanced tool for mimicking biophysical processes that naturally occur during the self-repair of wounds and damaged tissues, including electrostimulated regeneration. The piezoelectricity of PLLA strongly depends on the possibility of controlling its crystallinity and molecular orientation. Here, it is shown that modifying PLLA with a small amount (1 wt%) of crystalline filler particles with a high aspect ratio, which act as nucleating agents during drawing-induced crystallization, promotes the formation of highly crystalline and oriented PLLA structures. This increases their piezoelectricity, and the filler-modified PLLA films provide a 20-fold larger voltage output than nonmodified PLLA during ultrasound (US)-assisted activation. With 99% PLLA content, the ability of the films to produce reactive oxygen species (ROS) and increase the local temperature during interactions with US is shown to be very low. US-assisted piezostimulation of adherent cells directly attach to their surface (such as skin keratinocytes), stimulate cytoskeleton formation, and as a result cells elongate and orient themselves in a specific direction that align with the direction of PLLA film drawing and PLLA dipole orientation.

Evolution of nanostructured skin patches towards multifunctional wearable platforms for biomedical applications

Recent advances in the field of skin patches have promoted the development of wearable and implantable bioelectronics for long-term, continuous healthcare management and targeted therapy. However, the design of electronic skin (e-skin) patches with stretchable components is still challenging and requires an in-depth understanding of the skin-attachable substrate layer, functional biomaterials and advanced self-powered electronics. In this comprehensive review, we present the evolution of skin patches from functional nanostructured materials to multi-functional and stimuli-responsive patches towards flexible substrates and emerging biomaterials for e-skin patches, including the material selection, structure design and promising applications. Stretchable sensors and self-powered e-skin patches are also discussed, ranging from electrical stimulation for clinical procedures to continuous health monitoring and integrated systems for comprehensive healthcare management. Moreover, an integrated energy harvester with bioelectronics enables the fabrication of self-powered electronic skin patches, which can effectively solve the energy supply and overcome the drawbacks induced by bulky battery-driven devices. However, to realize the full potential offered by these advancements, several challenges must be addressed for next-generation e-skin patches. Finally, future opportunities and positive outlooks are presented on the future directions of bioelectronics. It is believed that innovative material design, structure engineering, and in-depth study of fundamental principles can foster the rapid evolution of electronic skin patches, and eventually enable self-powered close-looped bioelectronic systems to benefit mankind.

Piezoresistive MXene/Silk fibroin nanocomposite hydrogel for accelerating bone regeneration by Re-establishing electrical microenvironment

The electrical microenvironment plays an important role in bone repair. However, the underlying mechanism by which electrical stimulation (ES) promotes bone regeneration remains unclear, limiting the design of bone microenvironment–specific electroactive materials. Herein, by simple co-incubation in aqueous suspensions at physiological temperatures, biocompatible regenerated silk fibroin (RSF) is found to assemble into nanofibrils with a β-sheet structure on MXene nanosheets, which has been reported to inhibit the restacking and oxidation of MXene. An electroactive hydrogel based on RSF and bioencapsulated MXene is thus prepared to promote efficient bone regeneration. This MXene/RSF hydrogel also acts as a piezoresistive pressure transducer, which can potentially be utilized to monitor the electrophysiological microenvironment. RNA sequencing is performed to explore the underlying mechanisms, which can activate Ca²⁺/CALM signaling in favor of the direct osteogenesis process. ES is found to facilitate indirect osteogenesis by promoting the polarization of M2 macrophages, as well as stimulating the neogenesis and migration of endotheliocytes. Consistent improvements in bone regeneration and angiogenesis are observed with MXene/RSF hydrogels under ES in vivo. Collectively, the MXene/RSF hydrogel provides a distinctive and promising strategy for promoting direct osteogenesis, regulating immune microenvironment and neovascularization under ES, leading to re-establish electrical microenvironment for bone regeneration.

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MXene nanosheets could direct the selective growth of silk nanofibrils.

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Prepared MXene/RSF hydrogel exhibited good conductivity and sensing ability.

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The electroactive hydrogel could promote osteogenic differentiation of BMSCs by activating the Ca²⁺/CALM signaling pathway.

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The conductive system created an osteoblast–macrophage–endotheliocyte virtuous circle for bone microenvironment.

Electrotaxis of alveolar epithelial cells in direct-current electric fields

PURPOSE

This study aims to elucidate the electrotaxis response of alveolar epithelial cells (AECs) in direct-current electric fields (EFs), explore the impact of EFs on the cell fate of AECs, and lay the foundation for future exploitation of EFs for the treatment of acute lung injury.

METHODS

AECs were extracted from rat lung tissues using magnetic-activated cell sorting. To elucidate the electrotaxis responses of AECs, different voltages of EFs (0, 50, 100, and 200 mV/mm) were applied to two types of AECs, respectively. Cell migrations were recorded and trajectories were pooled to better demonstrate cellular activities through graphs. Cell directionality was calculated as the cosine value of the angle formed by the EF vector and cell migration. To further demonstrate the impact of EFs on the pulmonary tissue, the human bronchial epithelial cells transformed with Ad12-SV40 2B (BEAS-2B cells) were obtained and experimented under the same conditions as AECs. To determine the influence on cell fate, cells underwent electric stimulation were collected to perform Western blot analysis.

RESULTS

The successful separation and culturing of AECs were confirmed through immunofluorescence staining. Compared with the control, AECs in EFs demonstrated a significant directionality in a voltage-dependent way. In general, type Ⅰ alveolar epithelial cells migrated faster than type Ⅱ alveolar epithelial cells, and under EFs, these two types of cells exhibited different response threshold. For type Ⅱ alveolar epithelial cells, only EFs at 200 mV/mm resulted a significant difference to the velocity, whereas for, EFs at both 100 mV/mm and 200 mV/mm gave rise to a significant difference. Western blotting suggested that EFs led to an increased expression of a AKT and myeloid leukemia 1 and a decreased expression of Bcl-2-associated X protein and Bcl-2-like protein 11.

CONCLUSION

EFs could guide and accelerate the directional migration of AECs and exert antiapoptotic effects, which indicated that EFs are important biophysical signals in the re-epithelialization of alveolar epithelium in lung injury.

Development of a Microfluidic Chip Powered by EWOD for In Vitro Manipulation of Bovine Embryos

Digital microfluidics (DMF) holds great potential for the alleviation of laboratory procedures in assisted reproductive technologies (ARTs). The electrowetting on dielectric (EWOD) technology provides dynamic culture conditions in vitro that may better mimic the natural embryo microenvironment. Thus far, EWOD microdevices have been proposed for in vitro gamete and embryo handling in mice and for analyzing the human embryo secretome. This article presents the development of the first microfluidic chip utilizing EWOD technology designed for the manipulation of bovine embryos in vitro. The prototype sustains the cell cycles of embryos manipulated individually on the chips during in vitro culture (IVC). Challenges related to the chip fabrication as well as to its application during bovine embryo IVC in accordance with the adapted on-chip protocol are thoroughly discussed, and future directions for DMF in ARTs are indicated.

Biomaterials releasing drug responsively to promote wound healing via regulation of pathological microenvironment

Wound healing is characterized by complex, orchestrated, spatiotemporal dynamic processes. Recent findings demonstrated suitable local microenvironments were necessities for wound healing. Wound microenvironments include various biological, biochemical and physical factors, which are produced and regulated by endogenous biomediators, exogenous drugs, and external environment. Successful drug delivery to wound is complicated, and need to overcome the destroyed blood supply, persistent inflammation and enzymes, spatiotemporal requirements of special supplements, and easy deactivation of drugs. Triggered by various factors from wound microenvironment itself or external elements, stimuli-responsive biomaterials have tremendous advantages of precise drug delivery and release. Here, we discuss recent advances of stimuli-responsive biomaterials to regulate local microenvironments during wound healing, emphasizing on the design and application of different biomaterials which respond to wound biological/biochemical microenvironments (ROS, pH, enzymes, glucose and glutathione), physical microenvironments (mechanical force, temperature, light, ultrasound, magnetic and electric field), and the combination modes. Moreover, several novel promising drug carriers (microbiota, metal-organic frameworks and microneedles) are also discussed.

Fabrication and desired properties of conductive hydrogel dressings for wound healing

Conductive hydrogels are platforms recognized as constituting promising materials for tissue engineering applications. This is because such conductive hydrogels are characterized by the inherent conductivity properties while retaining favorable biocompatibility and mechanical properties. These conductive hydrogels can be particularly useful in enhancing wound healing since their favorable conductivity can promote the transport of essential ions for wound healing via the imposition of a so-called transepithelial potential. Other valuable properties of these conductive hydrogels, such as wound monitoring, stimuli-response etc., are also discussed in this study. Crucially, the properties of conductive hydrogels, such as 3D printability and monitoring properties, suggest the possibility of its use as an alternative wound dressing to traditional dressings such as bandages. This review, therefore, seeks to comprehensively explore the functionality of conductive hydrogels in wound healing, types of conductive hydrogels and their preparation strategies and crucial properties of hydrogels. This review will also assess the limitations of conductive hydrogels and future perspectives, with an emphasis on the development trend for conductive hydrogel uses in wound dressing fabrication for subsequent clinical applications.

Two-Layered Biomimetic Flexible Self-Powered Electrical Stimulator for Promoting Wound Healing

The repair of wound damage has been a common problem in clinic for a long time. Inspired by the electroactive nature of tissues and the electrical stimulation of wounds in clinical practice, the next generation of wound therapy with self-powered electrical stimulator is expected to achieve the desired therapeutic effect. In this work, a two-layered self-powered electrical-stimulator-based wound dressing (SEWD) was designed through the on-demand integration of the bionic tree-like piezoelectric nanofiber and the adhesive hydrogel with biomimetic electrical activity. SEWD has good mechanical properties, adhesion properties, self-powered properties, high sensitivity, and biocompatibility. The interface between the two layers was well integrated and relatively independent. Herein, the piezoelectric nanofibers were prepared by P(VDF-TrFE) electrospinning, and the morphology of the nanofibers was controlled by adjusting the electrical conductivity of the electrospinning solution. Benefiting from its bionic dendritic structure, the prepared piezoelectric nanofibers had better mechanical properties and piezoelectric sensitivity than native P(VDF-TrFE) nanofibers, which can convert tiny forces into electrical signals as a power source for tissue repair. At the same time, the designed conductive adhesive hydrogel was inspired by the adhesive properties of natural mussels and the redox electron pairs formed by catechol and metal ions. It has bionic electrical activity matching with the tissue and can conduct the electrical signal generated by the piezoelectric effect to the wound site so as to facilitate the electrical stimulation treatment of tissue repair. In addition, in vitro and in vivo experiments demonstrated that SEWD converts mechanical energy into electricity to stimulate cell proliferation and wound healing. The proposed healing strategy for the effective treatment of skin injury was provided by developing self-powered wound dressing, which is of great significance to the rapid, safe, and effective promotion of wound healing.

A Comprehensive Review on Barium Titanate Nanoparticles as a Persuasive Piezoelectric Material for Biomedical Applications: Prospects and Challenges

Stimulation of cells with electrical cues is an imperative approach to interact with biological systems and has been exploited in clinical practices over a wide range of pathological ailments. This bioelectric interface has been extensively explored with the help of piezoelectric materials, leading to remarkable advancement in the past two decades. Among other members of this fraternity, colloidal perovskite barium titanate (BaTiO₃ ) has gained substantial interest due to its noteworthy properties which includes high dielectric constant and excellent ferroelectric properties along with acceptable biocompatibility. Significant progression is witnessed for BaTiO₃ nanoparticles (BaTiO₃ NPs) as potent candidates for biomedical applications and in wearable bioelectronics, making them a promising personal healthcare platform. The current review highlights the nanostructured piezoelectric bio interface of BaTiO₃ NPs in applications comprising drug delivery, tissue engineering, bioimaging, bioelectronics, and wearable devices. Particular attention has been dedicated toward the fabrication routes of BaTiO₃ NPs along with different approaches for its surface modifications. This review offers a comprehensive discussion on the utility of BaTiO₃ NPs as active devices rather than passive structural unit behaving as carriers for biomolecules. The employment of BaTiO₃ NPs presents new scenarios and opportunity in the vast field of nanomedicines for biomedical applications.

Microcurrent and Gold Nanoparticles Combined with Hyaluronic Acid Accelerates Wound Healing

This study aimed to investigate the effects of iontophoresis and hyaluronic acid (HA) combined with a gold nanoparticle (GNP) solution in an excisional wound model. Fifty Wistar rats (n = 10/group) were randomly assigned to the following groups: excisional wound (EW); EW + MC; EW + MC + HA; EW + MC + GNPs; and EW + MC + HA + GNPs. The animals were induced to a circular excision, and treatment started 24 h after injury with microcurrents (300 µA) containing gel with HA (0.9%) and/or GNPs (30 mg/L) in the electrodes (1 mL) for 7 days. The animals were euthanized 12 h after the last treatment application. The results demonstrate a reduction in the levels of pro-inflammatory cytokines (IFNϒ, IL-1β, TNFα, and IL-6) in the group in which the therapies were combined, and they show increased levels of anti-inflammatory cytokines (IL-4 and IL-10) and growth factors (FGF and TGF-β) in the EW + MC + HA and EW + MC + HA + GNPs groups. As for the levels of dichlorofluorescein (DCF) and nitrite, as well as oxidative damage (carbonyl and sulfhydryl), they decreased in the combined therapy group when compared to the control group. Regarding antioxidant defense, there was an increase in glutathione (GSH) and a decrease in superoxide dismutase (SOD) in the combined therapy group. A histological analysis showed reduced inflammatory infiltrate in the MC-treated groups and in the combination therapy group. There was an increase in the wound contraction rate in all treated groups when compared to the control group, proving that the proposed therapies are effective in the epithelial healing process. The results of this study demonstrate that the therapies in combination favor the tissue repair process more significantly than the therapies in isolation.

Phosphatidylinositol 3-kinases play a suppressive role in cell motility of vegetative Dictyostelium cells

Phosphatidylinositol 3-Kinase (PI3K) is a key regulator of cell motility during chemotaxis and plays an important role in relaying and amplifying the shallow gradient of chemoattractant signals to ultimately mediate rearrangements of the actin cytoskeleton. To determine whether PI3K plays a similar role in electrotaxis as in chemotaxis, we examined directional cell migration in response to an electric field (EF) and unexpectedly found that the role of PI3K in regulating cell motility differs depending on the state of Dictyostelium cells. Contrary to chemotaxis experiments using aggregation-competent cells, in the cell migration assay, we used a recently developed method for electrotaxis using 3-h starved cells. Wild-type cells starved for 3 h showed increased motility in the presence of LY294002, a PI3K inhibitor, whereas aggregation-competent cells showed slightly decreased motility, indicating the effect of LY294002 on cell motility differ depending on the state of the cells. Consistent with these results, pi3k null cells in the vegetative state exhibited increased motility similar to that in the presence of LY294002, compared to wild-type cells. These findings were confirmed through random migration experiments. These results suggest that PI3Ks play a suppressive role in regulating cell motility of vegetative Dictyostelium cells and that the suppressive effect is reversed on inhibition or lack of PI3Ks, leading to high motility.

Pharmacodynamics of Dracorhodin Perchlorate and Its Inflammation-Targeting Emulsion Gel for Wound Healing

The mechanism of dracorhodin perchlorate for the repair of rat skin wounds was investigated. In order to screen a more favorable drug delivery system for wound repair, the therapeutic effect of dracorhodin perchlorate inflammation-targeted emulsion gel was compared with that of non-targeted emulsion gel on rat wounds. Compared with non-targeted emulsion gels, inflammation-targeted emulsion gels had a better transdermal penetration and lower potentials (−51.6 mV and −17.1 mV, respectively). The recovery of the wound from the dracorhodin perchlorate inflammation targeted emulsion gel group was better than that of the dracorhodin perchlorate inflammation non-targeted emulsion gel group and the positive drug group. Compared with the no-target emulsion gel group, the bFGF expression on day 7 and the EGF expression on day 14 in the targeted emulsion group showed 45.5% and 49.9% improvement, respectively. Pathological tissue slices showed that the epidermis, dermis, and basal layer inflammatory cells in the inflammation-targeted emulsion gel group and non-targeted emulsion gel group were significantly reduced, the granulation tissue proliferation was obvious, and the inflammation-targeted emulsion gel group was more effective. The results proved that dracorhodin perchlorate had a repairing effect on rat skin wounds, and its mechanism might be related to the promotion of the expression of EGF and bFGF in tissues.

The 3D printed conductive grooved topography hydrogel combined with electrical stimulation for synergistically enhancing wound healing of dermal fibroblast cells

Patients with extensive cutaneous damage resulting from poor wound healing often have other comorbidities such as diabetes that may lead to impaired skin functions and scar formation. Many recent studies have shown that the application of electrical stimulation (ES) to cutaneous lesions significantly improves skin regeneration via activation of AKT intracellular signaling cascades and secretion of regeneration-related growth factors. In this study, we fabricated varying concentrations of gelatin-methacrylate (GelMa) hydrogels with poly(3,4-ethylenedioxythiophene) (PEDOT): polystyrene sulfonate (PSS), which is a conductive material commonly used in tissue engineering due to its efficiency among conductive thermo-elastic materials. The results showed successful modification of PEDOT:PSS with GelMa while retaining the original structural characteristics of the GelMa hydrogels. In addition, the incorporation of PEDOT:PSS increased the interactions between both the materials, thus leading to enhanced mechanical strength, improved swelling ratio, and decreased hydrophilicity of the scaffolds. Our GelMa/PEDOT:PSS scaffolds were designed to have micro-grooves on the surfaces of the scaffolds for the purpose of directional guiding. In addition, our scaffolds were shown to have excellent electrical conductivity, thus leading to enhanced cellular proliferation and directional migration and orientation of human dermal fibroblasts. In vivo studies revealed that the GelMa/PEDOT:PSS scaffolds with electrical stimulation were able to induce full skin thickness regeneration, as seen from the various stainings. These results indicate the potential of GelMa/PEDOT:PSS as an electro-conductive biomaterial for future skin regeneration applications.

Promoting Re-epithelialization in an oxidative diabetic wound microenvironment using self-assembly of a ROS-responsive polymer and P311 peptide micelles

Engineering smart nano-therapeutics for re-epithelialisation of chronic wounds facilitates the wound healing process. However, due to excessive oxidative stress damage and persistent inflammation in diabetic wound microenvironment, the migration of stimulating epidermal cells in diabetic wounds represents a significant challenge. Here we synthesised P311-loaded micelles by self-assembly of P311 peptides and diblock copolymer poly (ethylene glycol)-block-poly (propylene sulfide) (PEG-b-PPS, denoted as PEPS) that have unique ability to transform an oxidative wound microenvironment into a proregenerative one while also providing cues for epidermal cell migration. The P311@PEPS showed an accelerated migration of epidermal cells via activation of the Akt signalling pathway, simultaneously suppressing the unfavourable oxidative wound microenvironment by scavenging reactive oxygen species (ROS), ultimately leading to the induction of an environment conducive to cell migration. Furthermore, the micelles were able to bypass the inhibitory effect of ROS on the Akt signalling pathway, thereby promoting epidermal cell migration. Additionally, we observed that diabetic wounds treated with P311@PEPS showed accelerated chronic wound healing, granulation tissue formation, collagen deposition and re-epithelialisation, thereby suggesting the efficacy of P311@PEPS as a promising nanoplatform for the treatment of chronic wounds. STATEMENT OF SIGNIFICANCE: Based on the unique conditions of the diabetic wound microenvironment, a smart drug delivery system with ROS-responsive nanomaterials has been widely investigated to enhance diabetic wound healing. In our previous studies, we observed that P311 promotes epidermal cell migration to induce wound re-epithelialisation. However, the application of P311 suffers from its instability. Herein, we developed a therapeutic platform with P311-loaded micelles (P311@PEPS), which were synthesized by the self-assembly of P311 peptides and diblock copolymer poly (ethylene glycol)-block-poly (propylene sulfide) (PEG-b-PPS, denoted as PEPS). These micelles provide continuous migration signals for epidermal cells by ROS-trigged P311 release. Additionally, P311@PEPS scavenges excess ROS and provides a microenvironment that reduces inflammation, which could protect P311 from enzymatic degradation and improve the bioavailability of P311.

A Shock to the (Nervous) System: Bioelectricity Within Peripheral Nerve Tissue Engineering

The peripheral nervous system has the remarkable ability to regenerate in response to injury. However, this is only successful over shorter nerve gaps and often provides poor outcomes for patients. Currently, the gold standard of treatment is the surgical intervention of an autograft, whereby patient tissue is harvested and transplanted to bridge the nerve gap. Despite being the gold standard, more than half of patients have dissatisfactory functional recovery after an autograft. Peripheral nerve tissue engineering aims to create biomaterials that can therapeutically surpass the autograft. Current tissue-engineered constructs are designed to deliver a combination of therapeutic benefits to the regenerating nerve, such as supportive cells, alignment, extracellular matrix, soluble factors, immunosuppressants, and other therapies. An emerging therapeutic opportunity in nerve tissue engineering is the use of electrical stimulation (ES) to modify and enhance cell function. ES has been shown to positively affect four key cell types, such as neurons, endothelial cells, macrophages, and Schwann cells, involved in peripheral nerve repair. Changes elicited include faster neurite extension, cellular alignment, and changes in cell phenotype associated with improved regeneration and functional recovery. This review considers the relevant modes of administration and cellular responses that could underpin incorporation of ES into nerve tissue engineering strategies. Impact Statement Tissue engineering is becoming increasingly complex, with multiple therapeutic modalities often included within the final tissue-engineered construct. Electrical stimulation (ES) is emerging as a viable therapeutic intervention to be included within peripheral nerve tissue engineering strategies; however, to date, there have been no review articles that collate the information regarding the effects of ES on key cell within peripheral nerve injury. This review article aims to inform the field on the different therapeutic effects that may be achieved by using ES and how they may become incorporated into existing strategies.

Possible Synergies of Nanomaterial-Assisted Tissue Regeneration in Plasma Medicine: Mechanisms and Safety Concerns

Cold atmospheric plasma and nanomedicine originally emerged as individual domains, but are increasingly applied in combination with each other. Most research is performed in the context of cancer treatment, with only little focus yet on the possible synergies. Many questions remain on the potential of this promising hybrid technology, particularly regarding regenerative medicine and tissue engineering. In this perspective article, we therefore start from the fundamental mechanisms in the individual technologies, in order to envision possible synergies for wound healing and tissue recovery, as well as research strategies to discover and optimize them. Among these strategies, we demonstrate how cold plasmas and nanomaterials can enhance each other's strengths and overcome each other's limitations. The parallels with cancer research, biotechnology and plasma surface modification further serve as inspiration for the envisioned synergies in tissue regeneration. The discovery and optimization of synergies may also be realized based on a profound understanding of the underlying redox- and field-related biological processes. Finally, we emphasize the toxicity concerns in plasma and nanomedicine, which may be partly remediated by their combination, but also partly amplified. A widespread use of standardized protocols and materials is therefore strongly recommended, to ensure both a fast and safe clinical implementation.

Influence of P(VDF-TrFE) Membranes with Different Surface Potentials on the Activity and Angiogenic Function of Human Umbilical Vein Endothelial Cells

During bone tissue regeneration, neovascularization is critical, and the formation of a blood supply network is crucial for bone growth stimulation and remodeling. Previous studies suggest that bioelectric signals facilitate the process of angiogenesis. Owing to their biomimetic electroactivity, piezoelectric membranes have garnered substantial interest in the field of guided bone regeneration. Nevertheless, the knowledge of their influence due to varying surface potentials on the progression of angiogenesis remains ambiguous. Therefore, we proposed the preparation of an electroactive material, P(VDF-TrFE), and investigated its effects on the activity and angiogenic functions of human umbilical vein endothelial cells (HUVECs). The HUVECs were directly cultured on P(VDF-TrFE) membranes with different surface potentials. Subsequently, cell viability, proliferation, migration, tube formation, and expressions of related factors were assessed through appropriate assays. Our results revealed that the negative surface potential groups exerted differential effects on the modulation of angiogenesis in vitro. The P(VDF-TrFE) membranes with negative surface potential exhibited the greatest effect on cellular behaviors, including proliferation, migration, tube formation, and promotion of angiogenesis by releasing key factors such as VEGF-A and CD31. Overall, these results indicated that the surface potential of piezoelectric P(VDF-TrFE) membranes could exert differential effects on angiogenesis in vitro. We present a novel approach for designing bioactive materials for guided bone regeneration.

A lateral electric field inhibits gel-to-fluid transition in lipid bilayers

We report evidence of lateral electric field-induced changes in the phase transition temperatures of lipid bilayers. Our atomic scale molecular dynamics simulations show that a lateral electric field increases the melting temperatures of DPPC, POPC and POPE bilayers. Remarkably, these shifts in the melting temperatures are only induced by lateral electric fields, and not normal electric fields. This mechanism could provide new mechanistic insights into lipid-lipid and lipid-protein interactions in the presence of endogenous and exogenous electric fields.

Interfaces Based on Laser-Structured Arrays of Carbon Nanotubes with Albumin for Electrical Stimulation of Heart Cell Growth

Successful formation of electronic interfaces between living cells and electronic components requires both good cell viability and performance level. This paper presents a technology for the formation of nanostructured arrays of multi-walled carbon nanotubes (MWCNT) in biopolymer (albumin) layer for higher biocompatibility. The layer of liquid albumin dispersion was sprayed on synthesized MWCNT arrays by deposition system. These nanostructures were engineered using the nanosecond pulsed laser radiation mapping in the near-IR spectral range (λ = 1064 nm). It was determined that the energy density of 0.015 J/cm² provided a sufficient structuring of MWCNT. The structuring effect occurred during the formation of C–C bonds simultaneously with the formation of a cellular structure of nanotubes in the albumin matrix. It led to a decrease in the nanotube defectiveness, which was observed during the Raman spectroscopy. In addition, laser structuring led to a more than twofold increase in the electrical conductivity of MWCNT arrays with albumin (215.8 ± 10 S/m). Successful electric stimulation of cells on the interfaces with the system based on a culture plate was performed, resulting in the enhanced cell proliferation. Overall, the MWCNT laser-structured arrays with biopolymers might be a promising material for extended biomedical applications.

Actin protein inside DMPC GUVs and its mechanical response to AC electric fields

Cells are dynamic systems with complex mechanical properties, regulated by the presence of different species of proteins capable to assemble (and disassemble) into filamentous forms as required by different cells functions. Giant unilamellar vesicles (GUVs) of DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) are systems frequently used as a simplified model of cells because they offer the possibility of assaying separately different stimuli, which is no possible in living cells. Here we present a study of the effect of acting protein on mechanical properties of GUVs, when the protein is inside the vesicles in either monomeric G-actin or filamentous F-actin. For this, rabbit skeletal muscle G-actin is introduced inside GUVs by the electroformation method. Protein polymerization inside the GUVs is promoted by adding to the solution MgCl₂ and the ion carrier A23187 to allow the transport of Mg⁺² ions into the GUVs. To determine how the presence of actin changes the mechanical properties of GUVs, the vesicles are deformed by the application of an AC electric field in both cases with G-actin and with polymerized F-actin. The changes in shape of the vesicles are characterized by optical microscopy and from them the bending stiffness of the membrane are determined. It is found that G-actin has no appreciable effect on the bending stiffness of DMPC GUVs, but the polymerized actin makes the vesicles more rigid and therefore more resistant to deformations. This result is supported by evidence that actin filaments tend to accumulate near the membrane.

Intelligent Wearable Sensors Interconnected with Advanced Wound Dressing Bandages for Contactless Chronic Skin Monitoring: Artificial Intelligence for Predicting Tissue Regeneration

Toward the adoption of artificial intelligence-enabled wearable sensors interconnected with intelligent medical objects, this contactless multi-intelligent wearable technology provides a solution for healthcare to monitor hard-to-heal wounds and create optimal efficiencies for clinical professionals by minimizing the risk of disease infection. This article addressed a flexible artificial intelligence-guiding (FLEX-AI) wearable sensor that can be operated with a deep artificial neural network (deep ANN) algorithm for chronic wound monitoring via short-range communication toward a seamless, MXENE-attached, radio frequency-tuned, and wound dressing-integrated (SMART-WD) bandage. Based on a supervised training set of on-contact pH-responsive voltage output, the confusion matrix for healing-stage recognition from this deep ANN machine learning revealed an accuracy of 94.6% for the contactless measurement. The core analytical design of these smart bandages integrated wound dressing of poly(vinyl acrylic) gel@PANI/Cu₂O NPs for instigating pH-responsive current during the wound healing process. Effectively, a chip-free bandage tag was fabricated with a capacitive Mxene/PTFE electret and adhesive acrylic inductance to match the resonance frequency generated by the intelligent wearable antenna. Under zero-current electrochemical potential, the wound dressing attained a slope of -76 mV/pH. With the higher activation voltage applied toward the wound dressing electrodes, cuprous ions intercalated more into the hybrid PVA gel/PANI shell, resulting in an exponential increase of the two-terminal current response. The healing phase diagram was classified into regimes of fast-curing, slow-curing, and no-curing for skin disease treatment with corticosteroids. Ultimately, the near-field sensing technology offers adequate information for guiding treatment decisions as well as drug effectiveness for wound care.

Short-term bioelectric stimulation of collective cell migration in tissues reprograms long-term supracellular dynamics

The ability to program collective cell migration can allow us to control critical multicellular processes in development, regenerative medicine, and invasive disease. However, while various technologies exist to make individual cells migrate, translating these tools to control myriad, collectively interacting cells within a single tissue poses many challenges. For instance, do cells within the same tissue interpret a global migration 'command' differently based on where they are in the tissue? Similarly, since no stimulus is permanent, what are the long-term effects of transient commands on collective cell dynamics? We investigate these questions by bioelectrically programming large epithelial tissues to globally migrate 'rightward' via electrotaxis. Tissues clearly developed distinct rear, middle, side, and front responses to a single global migration stimulus. Furthermore, at no point poststimulation did tissues return to their prestimulation behavior, instead equilibrating to a 3rd, new migratory state. These unique dynamics suggested that programmed migration resets tissue mechanical state, which was confirmed by transient chemical disruption of cell-cell junctions, analysis of strain wave propagation patterns, and quantification of cellular crowd dynamics. Overall, this work demonstrates how externally driving the collective migration of a tissue can reprogram baseline cell-cell interactions and collective dynamics, even well beyond the end of the global migratory cue, and emphasizes the importance of considering the supracellular context of tissues and other collectives when attempting to program crowd behaviors.

The innate immune system and fever under redox control: A Narrative Review

ABSTRACT:

In living cells, redox potential is vitally important for normal physiological processes that are closely regulated by antioxidants, free amino acids and proteins that either have reactive oxygen and nitrogen species capture capability or can be compartmentalized. Although hundreds of experiments support the regulatory role of free radicals and their derivatives, several authors continue to claim that these perform only harmful and non-regulatory functions. In this paper we show that countless intracellular and extracellular signal pathways are directly or indirectly linked to regulated redox processes. We also briefly discuss how artificial oxidative stress can have important therapeutic potential and the possible negative effects of popular antioxidant supplements.

Current Development in Interdigital Transducer (IDT) Surface Acoustic Wave Devices for Live Cell In Vitro Studies: A Review

Acoustics have a wide range of uses, from noise-cancelling to ultrasonic imaging. There has been a surge in interest in developing acoustic-based approaches for biological and biomedical applications in the last decade. This review focused on the application of surface acoustic waves (SAW) based on interdigital transducers (IDT) for live-cell investigations, such as cell manipulation, cell separation, cell seeding, cell migration, cell characteristics, and cell behaviours. The approach is also known as acoustofluidic, because the SAW device is coupled with a microfluidic system that contains live cells. This article provides an overview of several forms of IDT of SAW devices on recently used cells. Conclusively, a brief viewpoint and overview of the future application of SAW techniques in live-cell investigations were presented.

Ultrasound-activable piezoelectric membranes for accelerating wound healing

Ultrasonic energy harvesting technologies have gained much attention for biomedical applications due to their several desirable features including low-energy attenuation and strong penetration capability. In this work, flexible piezoelectric poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE))/barium titanate (BaTiO₃, BT) membranes, capable of converting ultrasound energy to electric energy, were fabricated by an electrospinning process and their effects on the wound healing behaviors with/without ultrasonic stimulation were investigated. The piezoelectric membranes showed excellent electric outputs and can be used as a sustainable power source to quickly charge LEDs and capacitors. The penetration capability of ultrasound waves was investigated by implanting the membranes at different depths of porcine tissue. The membrane was able to generate a high voltage of 8.22 V even at a depth of 4.5 cm. Furthermore, ultrasonic stimulation on the piezoelectric membranes facilitated the proliferation and migration of the fibroblasts, and a cell migration rate of 92.6% was obtained after 24 h in the cell migration test. Under ultrasonic vibration, the electric field generated from the membranes accelerated the wound closure rate in an animal wound model. These results demonstrated the effectiveness of the flexible piezoelectric membranes in stimulating cellular behaviors, which may provide a new therapeutic strategy for wound care.

In vitro dielectrophoresis of HEK cell migration for stimulating chronic wound epithelialization

This article describes a dielectrophoresis (DEP)-based simulation and experimental study of human epidermal keratinocyte (HEK) cells for wounded skin cell migration toward rapid epithelialization. MyDEP is a standalone software designed specifically to study dielectric particles and cell response to an alternating current (AC) electric field. This method demonstrated that negative dielectrophoresis (N_DEP ) occurs in HEK cells at a wide frequency range in highly conductive medium. The finite element method was used to characterize particle trajectory based on DEP and drag force. The performance of the system was assessed using HEK cells in a highly conductive EpiLife suspending medium. The DEP experiment was performed by applying sinusoidal wave AC potential at the peak-to-peak voltage of 10 V in a tapered aluminum microelectrode array from 100 kHz to 1 MHz. We experimentally observed the occurrence of NDEP, which attracted HEK cells toward the local electric field minima in the region of interest. The DIPP-MotionV software was used to track cell migration in the prerecorded video via an automatic marker and estimate the average speed and acceleration of the cells. The results showed that HEK cell migration was accomplished approximately at 6.43 μm/s at 100 kHz with 10 V, and F_DEP caused the cells to migrate and align at the target position, which resulted in faster wound closures because of the application of an electric field frequency to HEK cells in random locations.