Advancements and Applications of Electrospray Methods in Skin Tissue Regeneration

Abstract

Skin tissue engineering, a critical area within regenerative medicine, focuses on creating functional replacements for damaged or diseased skin. Electrospray ionization has emerged as a promising method in this field due to its precision in biomaterial and bioactive molecule deposition. This chapter discusses electrospray’s role in revolutionizing scaffold fabrication, cell encapsulation, and therapeutic delivery in skin engineering. Electrospray allows for the production of scaffolds that mimic the skin’s extracellular matrix, enhancing cell adhesion, proliferation, and differentiation. It also enables efficient encapsulation of growth factors, promoting sustained release at targeted sites to improve wound healing and skin regeneration. Electrospray-assisted fabrication of scaffolds has shown superior biocompatibility and structural features over traditional methods. Furthermore, the technology’s capability for directing cell and therapeutic delivery to wound sites introduce personalized treatment options for various skin conditions, making a significant advancement toward the clinical use of engineered skin tissues.

1. Introduction

During the last few years, interesting progress has been made in the field of tissue engineering, particularly in the development of innovative methods for skin tissue regeneration. In this vein, electrospray (ES) techniques have emerged as a pivotal technology, offering new possibilities for the precise deposition of bioactive materials and cells. This article seeks to explore the significant progress and applications of ES methods in skin tissue regeneration, highlighting the fusion of technology and biology that aims to enhance therapeutic outcomes [1, 2, 3].

Electrospray ionization (ESI) is a technique that has found novel applications in the biomedical field, especially for the fabrication of tissue scaffolds and the encapsulation of cells and drugs. The method involves the creation of an aerosol by applying a high-voltage to a liquid, which is then used to create fine particles or fibers. This ability to generate micro- and nanoparticles (NPs) with controlled size and distribution makes ES a valuable tool in tissue engineering [4, 5].

In recent advancements, the ES technique has been utilized for the co-deposition of multiple materials, including polymers, cells, and bioactive molecules, in a spatially controlled manner. For instance, researchers have successfully used the ES technique to create layered structures that mimic the natural architecture of human skin. Such structures are crucial for the successful integration of ES-engineered scaffolds with native tissues and for promoting wound healing [1, 6].

Young et al. [7] investigated the creation of synthetic hydrogel microspheres using submerged electrospray combined with UV photopolymerization, targeting cell encapsulation applications. The electrospray technique allows precise control over microsphere size from 50 to 1500 μm by manipulating the flow rate and voltage, which is beneficial for specific biomedical applications, such as drug delivery and cell therapy. The microspheres revealed cell viability higher than 90% after 24 h, underscoring the technique’s compatibility with sensitive biological entities like cells and proteins.

Moreover, the adaptability of ES technology has been broadened to include the incorporation of bioactive agents and cellular growth factors that enhance the regeneration of skin tissues. For example, a study conducted by Chen et al. [8] explored the use of microfluidic ES in creating a drug delivery system based on natural polysaccharides, demonstrating its effectiveness in promoting wound healing. This technique enhances skin tissue repair by ensuring targeted, sustained release of therapeutic agents directly to wound sites, thus accelerating cellular processes essential for skin regeneration.

The combination of ES techniques with other technological progressions like 3D printing and nanotechnology additionally unlocks fresh opportunities for developing intricate tissue structures. This integrative approach can lead to the development of highly functional and biomimetic tissues, which are vital for the treatment of severe burns and chronic wounds [5, 9].

As the field continues to evolve, further studies are required to optimize these techniques, particularly in the areas of material compatibility, the long-term viability of deposited cells, and the scaling of the technology for clinical applications. Ongoing research and development are expected to further refine the precision and efficacy of ES methods, making them indispensable in the realm of regenerative medicine [1, 5].

In conclusion, the advancements in ES technology are not only enhancing our understanding of tissue engineering but are also paving the way for groundbreaking applications in skin tissue regeneration. As this field progresses, it holds the promise of significantly improving patient outcomes in skin repair and regeneration.

2. Overview of skin tissue engineering

Skin tissue engineering is a rapidly advancing field aimed at developing effective treatments for severe skin injuries and diseases. Recent advancements focus on creating bioengineered skin substitutes that integrate both dermal and epidermal components, which are all-important for mimicking the natural structure and function of human skin.

One of the notable developments in this area is the use of biodegradable scaffolds, such as the NovoSorb™ Biodegradable Temporizing Matrix (BTM), which are designed to temporize wounds and promote the integration and establishment of dermal elements while resisting infection. These scaffolds are advantageous because they are inexpensive, easy to handle, and can be produced in large sheets, providing essential support for cellular growth and eventual wound closure [10].

Another critical aspect of skin tissue engineering is the interplay between different cell types. For example, the communication between fibroblasts and keratinocytes is essential for basement membrane synthesis, which is crucial for the stability and protection of engineered skin substitutes. This synergy supports the molecular bonding necessary for attaching the epidermis to the dermis [10].

Engineered Skin Substitutes (ESS) represent a significant breakthrough, combining autologous keratinocytes and fibroblasts within a bovine collagen-glycosaminoglycan scaffold. This model has shown promising clinical outcomes, especially in treating extensive burns, by reducing the need for donor skin grafts and improving survival rates [10].

Recent research also explores the incorporation of various cell types, such as melanocytes, microvascular endothelial cells, and even hair follicles into these engineered constructs, enhancing their functional and esthetic outcomes. The field continues to face challenges, particularly in terms of the immune response to xenogeneic materials (like bovine or porcine collagens) used in some dermal-epidermal substitutes. Synthetic scaffolds and autologous cell approaches are being explored to minimize these risks [10].

Additionally, the remodeling phase of healing, which involves the maturation of scars and the replacement of type III collagen with type I collagen, is critical for the long-term success of these treatments. Innovations in fetal tissue engineering also show potential for scarless healing, suggesting new directions for future research [11].

Overall, the field of skin tissue engineering holds great promise for improving patient outcomes in wound healing and skin replacement. Ongoing research aims to make these technologies more user-friendly, commercially viable, and effective in clinical settings [12].

2.1 Importance of skin regeneration

Skin regeneration, a vital aspect of dermatological science, involves intricate processes aimed at restoring the functional integrity and structure of skin after injuries such as burns, wounds, or surgical interventions. The regenerative capability of the skin is primarily facilitated by the interplay of skin stem cells and various signaling pathways that govern cell proliferation, differentiation, and migration. Recent studies highlight the indispensable role of mesenchymal stem cells (MSCs) due to their potent immunomodulatory effects, ability to differentiate into multiple cell types relevant to the skin, and secretion of paracrine factors that significantly accelerate wound healing [13, 14, 15, 16].

Technological progressions in tissue engineering have bolstered methods for skin regeneration. One instance is the refinement of collagen-based scaffolds to bolster cellular activities crucial for tissue repair. These scaffolds offer a conducive matrix to the effective integration and regeneration of skin tissues [17]. Nanomaterials have also been employed to improve these outcomes by fine-tuning the mechanical properties and degradation rates of scaffolds, which can be critical for matching the dynamic nature of skin tissue repair [18].

Moreover, the use of hydrogels in skin regeneration has seen significant advancements. Hydrogels are particularly effective due to their high-water content and soft tissue-like consistency, which makes them ideal for interacting with the natural skin environment. They promote cell adhesion, proliferation, and migration—all critical for tissue regeneration [19]. Moreover, it has been suggested that biomimetic methods capable of mirroring the structure of the extracellular matrix improve the healing process by offering signals that guide cell behavior and tissue growth [20].

The interplay between mechanical forces and cellular responses, known as mechanotransduction, has also been recognized as a key element in skin regeneration. Mechanical signals can alter cell behavior, influencing wound healing and potentially reducing scar formation by modulating fibrotic responses [21]. This highlights the need for a comprehensive understanding of both biological and mechanical factors in developing therapeutic strategies for skin repair and regeneration.

Overall, the combination of stem cell technology, advanced biomaterials, and an understanding of cellular mechanobiology provides a robust framework for enhancing skin regeneration. This integrated approach not only promises improved healing outcomes but also opens avenues for personalized therapeutic strategies tailored to individual healing needs and conditions [13, 17, 18, 19, 20, 21].

2.2 Challenges in skin tissue engineering

Expanding on the challenges in skin tissue engineering, one of the primary objectives remains the replication of the skin’s multilayered structure and its complex functions. Each layer of the skin—epidermis, dermis, and hypodermis—plays a specific role, and successful tissue engineering must replicate these to restore full functionality. This involves not only mimicking the physical barrier of the skin but also its sensory and thermoregulatory properties​ [12, 22].

The scalability of producing tissue-engineered skin also presents a significant challenge. The methods must not only be effective but also economically viable for widespread clinical use. Advances in manufacturing technologies, such as 3D printing and automated bioreactors, are being explored to scale up the production of skin substitutes that are consistent in quality and function​ [23, 24].

Infection control is another critical issue, particularly for wounds susceptible to bacterial contamination. Incorporating antimicrobial agents or designing materials that naturally reduce bacterial growth without harming the regenerative cells or the patient’s tissues is a key area of ongoing research​ [22, 25].

3. Fundamentals of electrospray technique

3.1 Principle of electrospray technology

ES technology, also known as electrohydrodynamic spraying, serves as a useful technique in various fields such as tissue engineering, drug delivery, and gene delivery systems. The process fundamentally relies on the dispersion of a liquid into fine droplets via an electric field, employing the principle of Coulombic repulsion to achieve this dispersion. As charges within the liquid repel, the liquid disintegrates into smaller droplets, a process crucial for the precise delivery mechanisms required in these fields [26, 27].

The operational mechanics of ES are highlighted by the formation of a Taylor cone at the liquid’s surface when subjected to a high-voltage. This conical shape results from the equilibrium between the electric field’s force and the liquid’s surface tension. Once the electric field’s strength exceeds a critical threshold, it disrupts the surface tension, initiating the ejection of a liquid jet from the cone’s apex. This jet then undergoes several instabilities, ultimately breaking into droplets whose sizes can vary from a few nanometers to several micrometers, suitable for targeted applications in medicine and engineering. Central to the ES setup are its core components, which include a syringe pump for controlled liquid flow, a nozzle that allows for the adjustment of droplet size, and a high-voltage power supply that charges the droplets. These droplets are subsequently collected after solvent evaporation. The ability to control droplet formation is vital for the success of the ES system, ensuring the achievement of specific particle characteristics necessary for the targeted applications, thereby underscoring the technique’s versatility and effectiveness in precise particle generation [27, 28, 29, 30, 31].

Structured micro/nanomaterials synthesized via ES offer unique properties and functionalities, making them valuable in biomedical applications. By controlling the composition and processing conditions, researchers can tailor the properties of the resulting materials to meet specific requirements for tissue engineering scaffolds, drug delivery carriers, and biosensors [27, 32].

By understanding the principles underlying ES technology and optimizing its parameters, researchers can harness its potential to advance various biomedical applications, from tissue engineering to drug delivery systems, offering innovative solutions to address complex healthcare challenges.

3.2 Parameters influencing the electrospray process

ES is a versatile technique widely employed in various fields, including tissue engineering, for its ability to precisely control the size, morphology, and composition of particles or fibers. Several parameters play crucial roles in determining the outcome of the ES process, as elucidated by recent studies [33].

Firstly, the choice of solvent(s) significantly impacts the ES process. The polarity, viscosity, and surface tension of the solvent affect the formation and stability of the Taylor cone, which is all-important for generating fine droplets or fibers. The study by Xu et al. delves into this aspect, highlighting how different solvents influence the properties of electrospray particles, such as size and morphology. Understanding solvent-solute interactions is imperative for optimizing ES parameters [34, 35].

Secondly, the flow rate of the solution being sprayed plays a crucial role in controlling droplet or fiber size and uniformity. Variations in flow rate affect the breakup dynamics of the jet emanating from the Taylor cone, thereby influencing the size distribution of the resulting particles or fibers. This parameter is extensively discussed in the study by Li et al., wherein the impact of flow rate on the morphology and encapsulation efficiency of electrospray particles is investigated. Additionally, the nozzle design significantly impacts the particle distribution and size. The size of the droplets is controlled through nozzle geometry and flow rate, further emphasizing the importance of mechanical configuration in achieving desired outcomes [28, 36].

Moreover, the choice of voltage applied during ES significantly influences the process. Voltage affects the surface charge density of the solution, thereby influencing the formation and stability of the Taylor cone and subsequent droplet or fiber generation. Molecular dynamics simulations, as discussed in the study by Xu et al., provide valuable insights into how different voltage conditions affect the dynamics of ES [37].

Lastly, parameters such as the distance between the needle tip and the collector, ambient humidity, and temperature also play crucial roles in the ES process, albeit to varying extents depending on the specific application and materials used [35].

3.3 Materials used in electrospray in tissue engineering

Materials like natural polymers (e.g., alginate, collagen) and synthetic ones (e.g., PLGA) are preferred due to their biocompatibility and controlled degradation rates, supporting the integration of engineered tissues​ [29, 30, 31, 38, 39].

Polymers used in ES techniques include both natural and synthetic materials. Natural polymers like alginate and collagen are particularly valuable due to their biocompatibility and biodegradability. They are used to create scaffolds that support cell proliferation and differentiation, mimicking the extracellular matrix. For instance, the gelatin-alginate composite has demonstrated remarkable utility in promoting wound healing, burn treatment, and other biomedical applications [40]. Synthetic polymers like PLGA offer versatility, providing customizable degradation rates and mechanical properties, which are critical for drug delivery systems. Advances in composite materials and the combination of natural and synthetic polymers have been highlighted by various research groups for their adaptability and compatibility​ [38, 40]. Injectable gels and hydrogels have also been explored for their potential in regenerative medicine, particularly using ES and related techniques for their preparation. These materials can be loaded with cells, growth factors, or drugs, and then precisely deployed to wound sites, providing a moist environment that facilitates tissue growth and repair. The versatility of these systems allows for the incorporation of various bioactive components that can be tailored to specific clinical needs [41].

4. Advancements in electrospray techniques

Recent advancements in ES techniques have significantly expanded their applicability in various scientific and technological fields, enhancing precision and efficiency. ES has been refined to create micro and NPs with controlled size and morphology, which is vital for applications such as drug delivery systems. This is achieved through precise manipulation of electrospray parameters such as voltage, flow rate, and needle size, allowing the production of tailored microspheres suitable for targeted drug delivery. For example, alginate microspheres have been developed for controlled release and encapsulation of therapeutic agents, capitalizing on alginate’s biocompatibility and biodegradability​ [42].

Further, ES has been combined with other technologies to improve outcomes in fields such as tissue engineering and vascularization. The electrospray bioprinting method developed by Jack et al. was pivotal in enhancing vascularization by rapidly generating hydrogel microspheres encapsulating vascular endothelial growth factor (VEGF)-overexpressing HEK293T cells. These microspheres effectively promoted angiogenesis in a mouse hind-limb ischemia model. The controlled release of VEGF from the microspheres induced collateral vessel formation, vital for therapeutic angiogenesis aimed at treating limb ischemia. The study demonstrated that applying increased voltage using the electrospray method not only refined microsphere size but also ensured the targeted delivery and sustained release of VEGF, enhancing vascularization and tissue repair in ischemic conditions [43].

Additionally, the integration of ES with nanospray desorption techniques has fostered advancements in mass spectrometry, enabling the direct, in-depth analysis of metabolites from biological samples. This combination facilitates a minimal sample preparation approach, maintaining the integrity and original distribution of the metabolites on sample surfaces​ [44].

In biomedical engineering, ES is used in conjunction with other encapsulation techniques to enhance the delivery and efficacy of probiotics and other therapeutic agents. This includes the development of novel biomaterials that can protect active ingredients against harsh gastrointestinal environments, thereby increasing the survival and delivery efficiency of therapeutic microbes​ [44].

5. Electrospray techniques in skin tissue engineering

5.1 Application of electrospray in skin cell deposition

The application of ES in skin cell deposition is gaining traction due to its capacity to create micro- and nano-scale structures beneficial for skin tissue engineering. ES offers a highly controlled method for depositing cells and biomaterials onto various substrates, which is essential for the precise construction of skin layers.

For instance, the deposition of fibroblasts using ES has shown promising results in maintaining cell viability and function, essential for effective skin regeneration [45, 46]. Zheng et al. have explored the use of ES for depositing zinc oxide (ZnO) thin films, which are utilized in sensors but have potential applications in skin tissue engineering due to their biocompatibility and microbial resistance [45].

Moreover, the precision of ES allows for the deposition of cells in defined patterns, mimicking the natural extracellular matrix and thus promoting better cell adhesion and proliferation. This technique surpasses traditional methods like manual cell seeding or random fibroblast spraying, which lack control over cell distribution and density [46, 47].

Recent advancements have also explored combining ES with other technologies. For example, combining ES and bioprinting has been proposed to fabricate complex tissue structures by precisely placing cells and scaffolds layer by layer, further enhancing the mimicry of natural skin architecture [45].

ES deposition represents a promising frontier in skin tissue engineering, offering advancements in how cells and materials are layered and integrated into functional tissue constructs. This approach could significantly improve the outcomes of skin regeneration therapies, making them more efficient and effective.

5.2 Role in the fabrication of skin tissue scaffolds

ES is a beneficial method for producing scaffolds for skin tissue, allowing for the generation of particles at micro- and nano-scales. Unlike electrospinning, which focuses on fiber production, ES uses electrical forces to produce droplets of polymer solutions. These particles can be functionalized with bioactive agents like growth factors or drugs, promoting wound healing and providing an environment conducive to tissue regeneration [48, 49].

In the context of skin tissue engineering, electrosprayed particles loaded scaffolds support cell attachment and proliferation, essential processes in skin regeneration. Their high surface area-to-volume ratio enhances the scaffolds’ ability to deliver therapeutic compounds efficiently. For instance, scaffolds can be loaded with growth factors, which stimulate cell growth, differentiation, and migration, aiding wound healing [25].

A significant advantage of the ES technique is its compatibility with different materials. Both synthetic and natural polymers can be used, allowing for the design of scaffolds with customizable properties such as mechanical strength, degradation rate, and biological functionality. These customizable features can be tailored to meet specific clinical needs, such as treating diabetic ulcers or extensive burn injuries [50].

ES is a versatile and promising tool for producing innovative scaffolds in skin tissue engineering. By enabling precise control over the delivery of bioactive agents and scaffold architecture, it offers significant potential for developing effective, personalized treatments in regenerative medicine.

5.3 Delivery of growth factors and bioactive molecules

Growth factors play an important role in wound healing and tissue regeneration by promoting cell proliferation and migration, modulating immune responses, and enhancing the formation of extracellular matrix. Alginate, combined with other biopolymers like sericin and platelet lysate, has been used to create bioactive wound dressings that release growth factors in a controlled manner, thereby accelerating the healing process in skin lesions. This approach uses the ES technique to encapsulate these molecules within biodegradable materials, which can then be applied directly to wound sites for improved healing outcomes​ [51].

The use of scaffolds in skin tissue engineering is another significant area where ES techniques are beneficial. Scaffolds provide a 3D structure that supports cell adhesion, growth, and differentiation. Materials like chitosan and polylactic-co-glycolic acid (PLGA) have been utilized to create nanofibrous scaffolds that mimic the natural extracellular matrix of the skin. These scaffolds can be functionalized with growth factors like basic fibroblast growth factor (bFGF) and transforming growth factor beta 1 (TGF-β1), which are critical for promoting skin regeneration and reducing scarring​ [52, 53].

ES technique is important in advancing wound dressing technology by enabling precise deposition of bioactive molecules on fabrics, which plays a crucial role in controlled drug release and targeted therapeutic actions. Zhang et al. [54] utilized the electrospray technique to apply a polydimethylsiloxane (PDMS) coating on one side of a chitosan-loaded cotton fabric, creating a Janus bandage with hydrophilic and hydrophobic properties. This unique structure facilitated unidirectional moisture management, crucial for maintaining optimal wound moisture, during the healing process. The bandage showed a one-way transport index of 1068%, indicating highly efficient moisture transfer away from the wound. Moreover, the bioactive coating ensured sustained release of antimicrobial agents, significantly enhancing fibroblast proliferation and reducing infection risks at the wound site, thus accelerating the healing process.

6. Case studies: success stories in skin regeneration

6.1 Detailed accounts of successful applications

In the realm of tissue engineering, the ES technique has been harnessed successfully to foster advancements in skin regeneration. Below are several illustrative case studies from recent years that highlight these developments:

Jayarajan et al. [55] demonstrated that bio-electrospray could effectively reconstruct 3D organotypic human skin tissues with high cell viability using a hydrogel mixed with human fibroblasts. The results showed that bio-electrospray facilitated the formation of skin tissues with varying epidermal thickness. Specifically, manually seeded constructs had an epidermal thickness of approximately 30 μm, while bio-electrospray constructs displayed an inconsistent thickness due to the impact of larger cell-bearing droplets. These findings underscore the potential of bio-electrospray in tissue engineering, suggesting its capability to handle and integrate high concentrations of cells into complex tissue structures effectively.

Another significant study explored the use of ES to apply shrimp and mushroom-derived chitin nanofibrils onto cellulose tissues, targeting skin contact applications. The findings showed that this application significantly enhanced the anti-inflammatory properties of the cellulose, with cytokine inhibition efficiency reaching up to 67%. Moreover, the ES technique maintained over 90% viability for human dermal keratinocytes, emphasizing its suitability for creating biocompatible and functional skincare materials. These results highlight the potential of ES in developing innovative, bio-based products for skin care applications [56]. Figure 1 revealed that HaCaT cells (human epidermal keratinocyte line) were viable in all the electrosprayed cellulosic tissues. Only a few dead cells were observed, with no differences between the different samples.

Figure 1.

Direct cytotoxicity test: Live/Dead viability test performed on HaCaT cell line seeded on cellulose tissues electrospray with (a) shrimp chitin nanofibrils (sCNs) (water); (b) sCNs (water/acetic acid); (c) sCNs (water/HFlP); (d) mushroom chitin nanofibrils (mCNs) (water); (e) mCNs (water/acetic acid). (f) Pristine cellulose tissue. Viable cells are stained in green, dead cells are stained in red, and the cellulosic tissue shows autofluorescence mainly in the red channel. Adopted with permission [56].

In the innovative study, Luo et al. [57] employed a microfluidic electrospray technique to produce discal microparticles (DMPs) loaded with therapeutic agents for enhanced wound healing. The effectiveness of this method was notably evident in the significant results observed in the angiogenesis process, crucial for wound repair. Specifically, the DMPs+drugs group demonstrated a marked increase in the formation of new blood vessels, as indicated by the measurement of “tube length.” This term refers to the length of tube-like structures formed by endothelial cells, which are used as a quantitative indicator of new blood vessel growth. The results revealed an impressive 63% increase in tube length, with the treated group achieving an average tube length of 1.8 mm compared to just 1.1 mm in the control group. These findings clearly highlight the electrospray’s capacity to enhance therapeutic delivery and efficacy, accelerating the healing process by promoting more robust and rapid angiogenesis.

Research has explored the regenerative and anti-aging capacities of adipose-derived stem cells (ADSCs) loaded with growth differentiation factor 11 (GDF11) using the ES technique. This combination has been found to enhance skin integrity, density, and strength, while also reducing wrinkles. The study indicates that ADSCs, when electrospray with bioactive factors like GDF11, can significantly contribute to skin rejuvenation and repair processes [58].

A study documented the use of ES to deposit silver nanoparticles (AgNPs) on radiosterilized porcine skin to prevent infections in deep burn wounds help maintain cell viability and promote cell growth. This innovative approach used an ES technique to apply a solution of AgNPs directly to the skin, enhancing its antimicrobial properties and thus reducing the risk of infection in severe burn injuries. This method highlights the potential of combining NP technology with the ES technique to improve outcomes in critical care scenarios​ [59]. Figure 2 provides an insightful overview of the impact of AgNPs on fibroblast viability, with micrographs and quantitative data demonstrating the distinctions between live and dead cells and offering a comparative assessment of their counts and proportions. It reveals that while low concentrations of AgNPs maintain high cell viability in human dermal fibroblasts, increasing the concentration leads to significant reductions in both the number and viability of cells. At the lowest concentration (0.055 M), viability is at 99%, but it decreases to 85% at the highest concentration (0.500 M). This indicates a concentration-dependent cytotoxic effect of AgNPs on cell viability and number.

Figure 2.

Viability of fibroblasts exposed to electrospray AgNPs. The effect of AgNPs from porcine skin on fibroblast viability was measured. (A) Micrographs of viable cells (calcein/green) and dead cells (ethidium homodimer/red); (B) number of living and dead cells; and (C) percentage of living and dead cells. Adopted with permission [59].

These case studies exemplify how the ES technique is being utilized to create and optimize bioactive scaffolds that enhance skin regeneration. By manipulating various biomaterials and cellular components, researchers can tailor properties that meet specific therapeutic needs, paving the way for advanced solutions in skin repair and regeneration.

6.2 Discussion on the impact of electrospray techniques on patient outcomes

The impact of ES technique in skin tissue engineering is a burgeoning area of research that promises significant advancements in patient outcomes, particularly in wound healing and skin regeneration. ES and related techniques, such as electrospinning, have been essential in the development of nanofibrous scaffolds that mimic the extracellular matrix, thereby enhancing tissue integration and cellular interactions.

ES deposition, for instance, is utilized to create fine mists of collagen particles, which are then directed onto target surfaces. This technique is especially valuable in the pharmaceutical and biomedical fields due to its precision and the ability to maintain the stability and activity of the sprayed particles. The resultant collagen nanostructures are ideal for drug delivery applications and are used to enhance the healing processes in tissue engineering [60].

In the realm of skin tissue engineering, the structural properties of scaffolds created via ES and electrospinning are of paramount importance. These scaffolds provide a three-dimensional matrix that supports cell attachment, proliferation, and differentiation, all of which are essential for effective tissue regeneration. Recent advancements have highlighted the role of NP additives in these processes, such as ZnO and graphene, which confer additional antibacterial properties and enhance the mechanical integrity of the scaffolds [61, 62].

The versatility of ES techniques extends to the creation of hybrid scaffolds that combine both synthetic and natural polymers, improving the overall functionality of the scaffolds. These hybrid materials demonstrate improved mechanical properties, stability, and bioactivity, which are critical for their performance in vivo [61].

Furthermore, the use of nature-derived polymers in ES applications, such as cellulose and its derivatives, has been explored for their biocompatibility and environmental stability. These materials offer the potential for controlled degradation, which is beneficial for temporary scaffolds that need to support tissue formation and then degrade safely within the body [61].

ES techniques significantly impact patient outcomes in skin tissue engineering by providing sophisticated tools for creating advanced biomaterials that support wound healing and tissue regeneration. The ongoing development of these technologies suggests a promising future for their application in regenerative medicine and other biomedical fields.

6.3 Comparative analysis with traditional skin regeneration methods

ES and traditional methods of skin regeneration each bring unique approaches and technologies to the field of tissue engineering. The adoption of ES techniques, particularly in the generation of nano and microscale fibers, presents an innovative path that diverges significantly from more conventional methods like grafting or the use of biomaterial scaffolds.

Traditional skin regeneration methods have largely relied on direct transplantation and the application of skin grafts, including autografts, allografts, and xenografts. These methods, while effective in many contexts, often face limitations due to donor site scarcity, potential for immune rejection, and infection risks. Additionally, the mechanical properties and integration of these grafts can vary, potentially complicating the healing process [41, 63].

In contrast, ES technology offers a highly versatile platform for creating tailored tissue scaffolds that can enhance cell attachment, proliferation, and differentiation. The technique allows for the precise deposition of polymers, cells, and active compounds in an organized manner, enabling the development of structures that closely replicate the natural architecture of skin tissue. This level of control is particularly beneficial for promoting proper tissue integration and function [63, 64].

Recent advancements have demonstrated the potential of ES in delivering bioactive molecules effectively. For instance, research has shown that ES can be used to encapsulate and subsequently release growth factors in a controlled manner, which is crucial for modulating wound healing processes. This method ensures sustained release, which is often necessary for the prolonged durations required in tissue regeneration scenarios [64].

Furthermore, the integration of ES with other technologies like 3D bioprinting has been explored, resulting in hybrid techniques that leverage the strengths of both approaches. For example, the combination of 3D printing and ES has been utilized to create layered structures that offer mechanical support and active biological functionality, which are essential for effective skin regeneration [41].

While traditional skin regeneration techniques continue to be valuable, ES and related advanced manufacturing technologies represent a significant step forward. These methods provide enhanced capabilities for creating more complex, functional, and personalized tissue constructs that could lead to improved patient outcomes in skin repair and regeneration. The ongoing development and refinement of these technologies hold promise for addressing the limitations of existing methods and expanding the possibilities within the field of tissue engineering.

7. Challenges and limitations

ES technology holds significant promise for skin tissue engineering, particularly in the encapsulation and controlled release of bioactive molecules. However, several challenges and limitations must be addressed to optimize its efficacy. One major issue is the precise control over droplet size and distribution, which is crucial for creating uniform particles and fibers. Inconsistent droplet formation can lead to nonuniform scaffold structures, adversely affecting cell growth and tissue regeneration outcomes. Achieving and maintaining the stability of the Taylor cone, especially with solutions of varying viscosities and conductivities, requires meticulous fine-tuning of parameters such as voltage and flow rate, which can be time-consuming and labor-intensive [65].

Moreover, the integration of ES with other techniques like electrospinning to fabricate hybrid scaffolds introduces additional complexity. Ensuring material compatibility and maintaining the structural integrity of combined scaffolds are significant engineering challenges. Hybrid scaffolds must achieve desired mechanical properties while retaining the bioactivity of incorporated molecules, necessitating extensive optimization and iterative testing. This complexity often involves a trial-and-error approach to balance mechanical robustness and biological functionality [66].

Scaling up the ES process for clinical applications presents another substantial challenge. Laboratory-scale experiments show potential, but translating these findings to large-scale production involves addressing batch-to-batch variability, equipment scalability, and compliance with stringent regulatory standards. Ensuring that ES-based products meet quality and safety standards essential for medical use is a demanding task, requiring rigorous validation and quality control measures [67].

8. Future directions

ES is emerging as a promising technique in skin tissue engineering due to its ability to generate finely controlled particles and droplets. Its future directions lie in integrating with advanced technologies like nanotechnology, 3D printing and biofabrication, enabling more complex and functional skin tissue structures.

The convergence of ES with nanotechnology holds significant potential for enhancing biofabrication strategies. Nano-biomaterials can be embedded into bio-inks via ES, providing targeted delivery of growth factors or drugs and mimicking the extracellular matrix structure to trigger specific cell responses. For instance, embedding nano-biomaterials within bio-inks has demonstrated success in delivering growth factors like TGF-β1 for cartilage regeneration. These nano-carriers protect and sustainably release their cargo, which could be crucial for controlled differentiation in skin tissue engineering​ [68].

The ability of ES to produce particles of controlled sizes complements 3D printing technologies by enhancing the layering of bio-inks and ensuring uniform particle distribution in engineered tissues. Advanced biofabrication techniques can leverage this to produce more complex, multilayered structures that closely mimic native skin. For instance, research on cardiac tissue engineering illustrates how ES can contribute to improved bio-ink formulations, enhancing the layering and integration of cells and scaffolds within 3D-printed constructs​ [69].

Despite promising advancements, challenges like bio-ink printability, cell viability, and material compatibility need resolution. Future research aims to optimize bio-ink formulations with tailored mechanical and chemical properties, making them suitable for ES processing. Moreover, integrating ES with real-time monitoring systems could refine the printing process to achieve more precise control over the tissue structures produced [68, 69].

Overall, the future of ES in skin tissue engineering appears promising, especially when combined with these advanced technologies. The interdisciplinary approach will be a key to unlocking new potentials and overcoming current limitations.

9. Conclusion

The ES technique is a valuable tool in skin tissue engineering, offering precise fabrication of cell-seeded scaffolds and controlled delivery of bioactive molecules. This precision enhances cell adhesion and growth, while its compatibility with various biomaterials makes it suitable for diverse tissue scaffolds. The technology shows promise for personalized skin grafts and sophisticated wound healing through multilayered structures and controlled release of therapeutic agents.

Moving forward, ES’s integration with emerging technologies like bioprinting and improvements in operational parameters can lead to significant clinical applications. Collaboration among researchers, clinicians, and industry will be crucial to overcoming technical challenges and accelerating its transition to clinical use. With a concerted effort, ES technology could revolutionize skin regeneration and treatment.