1 Introduction

Essential oils (EOs) are compounds extracted from aromatic plants that have undergone extensive research in the food and pharmaceutical industries [1]. This is due to their diverse range of bioactive properties, including antioxidant, antimicrobial, and anti-inflammatory effects [2]. Eucalyptus Essential oil (EEO) is one of the main products obtained from the Eucalyptus leaves known for its volatile organic compounds, abundant in 1,8-cineole concentration, monoterpenes, sesquiterpenes, aldehydes, and ketones [3, 4]. Attributed to its delightful flavor and aroma 1,8-cineole incorporated EEO achieved to be used as a common ingredient in the fields of food, medicine, fragrances, and cosmetics [5]. Upon exposure to light, heat, and atmospheric oxygen, bioactive components of EOs can readily undergo oxidation and degradation [6]. Pure EOs tend to be volatile, meaning easily evaporate and are insoluble in water. Additionally, EOs may possess taste or odor characteristics that are considered undesirable so, further application of EOs is limited [1, 7]. However, a viable alternative solution to tackle these obstacles is to encapsulate EOs within fibrous webs/fabrics [8]. Recent studies revealed that these fibers are produced through a novel technology, the Electroblowing (E-B) [9].

E-B is an innovative and state-of-the-art technique utilized for the fabrication of different-size fibers, nano-to-micro scale. This fabrication method is a synergistic combination of electrospinning (ES) and solution blow spinning (SBS) [9]. Hence, from various synthetic and/or bio-based polymers high-quality fibrous materials fabricated via E-B are used in air filtration [10,11,12,13], food packaging [14, 15], tissue engineering [16], drug release [17], and so on. This was achieved because of the morphological structure of fiber-based materials crucial for delivering EOs. In addition, the nanofibrous web’s large surface-to-volume ratio compared to other nanostructures plays a vital role in the delivery system of EOs [18]. Synthetic polymer-based fibers possess favorable processability and mechanical properties. However, their hydrophobic nature and lack of surface cell recognition sites restrict their utilization in biomedical domains [19]. On the other side, a wide range of natural polymeric nanofibers such as gelatin, chitosan, cellulose, and others have been employed for the encapsulation of EOs [18]. Nevertheless, their low mechanical strength should be taken into consideration. In addition, the weak hydrogen bonding between chitosan films and EOs might cause no significant change in the retention and release characteristics of chitosan film encapsulated with EOs [6]. Incorporating additional encapsulating agents, such as emulsifiers or polymers like gelatin, into the chitosan matrix could address these drawbacks [20]. Further, a literature survey exhibited that the thermal stability of EOs improved due to the effect of encapsulation within the fibrous webs [21].

Gelatin, derived from collagen in animals, is a highly abundant protein that finds extensive applications in the food, pharmaceutical, and cosmetic industries [2, 22]. This is primarily due to its rich composition of proline, glycine, and hydroxyproline [23]. Besides, gelatin is edible, cheap, biodegradable, and biocompatible natural polymer [24]. Despite this, the hydrophilic nature of gelatin leads to a challenge in its use for food packaging, as it hampers its ability to provide an effective moisture barrier. Thermal crosslinking is one possible solution for improving the surface wettability of gelatin nanofibrous webs. Conversely, when it comes to materials used for wound dressings, a certain level of hydrophilicity is required for them to function effectively. Herein, hydrophobic materials are unsuitable for wound dressing, as they cannot release antibacterial and/or other therapeutic agents that may be loaded within the fibers [25]. For this reason, it is necessary to have a certain level of hydrophilicity to adhere to biological surfaces. The study by Kim et al. showed that adding gelatin to polyurethane (PU) nanofibers increased their PU nanofibers’ hydrophilicity, potentially promoting fibroblast adhesion and tissue growth [26]. Moreover, nanofibers spun from pure gelatin lack sufficient bioactivity characteristics so it is difficult to apply them for wound dressing and the prevention of food from microbial attack. Researchers have tackled this problem by blending gelatin with chitosan. Nevertheless, chitosan alone may not provide enough antimicrobial activity. Accordingly, EOs are utilized to enhance the antimicrobial and antioxidant properties of the fibrous webs. Therefore, gelatin-based nanofibrous webs utilized in the fields of active food packaging and wound dressing are produced using biopolymer-based matrix materials incorporated with EOs. This integration aims to preserve volatile components of EOs and prevent them from deterioration [18]. Compared to traditional film-based packaging and wound dressing materials, gelatin-chitosan electro-blown nanofibers have exceptional properties that make them highly sensitive to changes in acidity/alkalinity. Thereafter, allowing them for precise control over the release of bioactive compounds embedded within the pores of fibers [27]. Thus, all these properties make gelatin-chitosan nanofibers an ideal choice to apply for food packaging and wound dressings.

Active food packaging is a novel approach aimed at safeguarding the quality of food by shielding it from external factors that could potentially spoil the food [14]. With this regard, numerous studies have been carried out by incorporating active antimicrobial and antioxidant agents into packaging materials. Can et al. investigate electrospun gelatin nanofibers with lemongrass essential oil (Gt/LEO) as potential antimicrobial biodegradable and active food packaging [21]. Their study revealed that the growth inhibition rate (GIR) of Gt/10% LEO nano-films reached a maximum of 99.09% against Staphylococcus aureus and 96.63% against Salmonella Typhimurium. In another study, a novel form of edible active food packaging is studied using centrifugally spun micro-nanofibers derived from lemon peel oil/gelatin [28]. The study showed that the shelf life of cheese was positively influenced by the addition of gelatin centrifugally spun with lemon peel oil, as it effectively inhibited the growth of aerobic mesophilic bacteria and yeast molds responsible for spoilage. Commercial biopolymer films are currently limited to use in foods that have a short shelf life or perishable goods like fruits and vegetables, which rely on respiration and humidity [29]. Despite the favorable qualities of nanofibers for food packaging, the majority of packaging materials are still made from polymer films, with limited research conducted on nanofibers in this field.

Wound dressings serve multiple purposes, including stopping bleeding, protecting against infections, absorbing excessive exudates, and promoting wound hydration to expedite the healing process through the inclusion of bioactive elements [6]. Conventional dressings including cotton wool, lint, and gauze are employed for averting bacterial infections; however, these dressings tend to adhere to the wound and fail to establish an appropriate level of moisture [30]. Consequently, the removal of such dressings made from films can lead to harm to the area surrounding the wound. As a result, numerous researches have been carried out on fiber-based materials applicability on wound dressings. Elbhnsawi et al. studied the potential utilization of nanofibers produced from Eucalyptus oil/cellulose acetate and nano-chitosan/Eucalyptus oil/cellulose acetate for efficient wound dressing applications [31]. Their study found that the tested pathogens were effectively inhibited by eucalyptus oil, displaying strong antimicrobial activity. Notably, the highest recorded values for inhibition zone diameter, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) were observed against Staphylococcus aureus, measuring at 15.3 mm, 16.0 g/mL, and 256 g/mL, respectively. The application of electrospun PVP/GEL nanofibers incorporating different concentrations of clove essential oil (CLEO) and EEO was examined for biomedical purposes [32]. CLEO nanofibers exhibited greater inhibition zones compared to EEO nanofibers. Herein, C. albicans revealed a greater susceptibility to CLEO-based nanofibers compared to E. faecalis, which was significantly affected by EEO-based nanofibers.

To sum up, nowadays the majority of food packaging and wound dressing materials are made from petroleum-derived plastics designed for single-use and are non-degradable [33]. This is due to plastics are cost-effective, easy to process, lightweight, chemically resistant, and have diverse physical characteristics [34]. Despite that, when disposed them into the environment the plastics release toxic chemicals. This renders them a remarkable contributor to pollution and causes harm to living things in their natural habitats. Further, the continuous growth of the global population is contributing to the worsening environmental pollution caused by the consumption of large tons of plastic-based food packaging and wound dressing materials worldwide. Thus, it is imperative to take immediate action, to develop eco-friendly bio-based materials applicable for packaging and wound dressings.

Therefore, this study explores the applicability of EEO-incorporated gelatin-chitosan biopolymer-based nanofiber webs produced by E-B for potential uses in active food packaging and wound dressing applications. To gain a deeper comprehension of the sample’s behavior, several characterization techniques were applied, including SEM, FTIR, and TGA. These techniques were employed to analyze the fiber morphology, physical and chemical interaction, as well as thermal behaviors observed during the integration of EEO within the gelatin-chitosan nanofibrous network. Additionally, antioxidant, antimicrobial, air permeability, contact angle, and mechanical properties were also assessed. What sets this research apart is the innovative approach of incorporating a natural essential oil, EEO, as an antioxidant and antibacterial agent into the gelatin-chitosan nanofibrous nonwoven webs. The combination of gelatin, chitosan, and EEO has not been extensively investigated before; this makes this research a pioneering effort in the field. Moreover, the findings of this research will not only expand the knowledge in the field but also pave the way for the development of advanced active food packaging and wound dressing materials that will enhance food shelf life and therapeutic properties. To conclude, this study believed that the electro-blown nanofibrous webs produced from gelatin-chitosan loaded with EEO showcase great potential as biodegradable materials with enhanced antioxidant and antimicrobial properties, suitable for applications in food packaging and wound dressings.

2 Materials and Methods

2.1 Materials

Dried eucalyptus leaves (Eucalyptus globulus) were acquired from a local herbalist in Kayseri, Turkey. Gelatin (G) (Type B, Bloom 250–270) was supplied from Halavet Gıda LLC (Istanbul, Türkiye) and chitosan (C, medium molecular weight deacetylation degree of 75%–85%) was purchased from BIOPOLY, (Türkiye). Glacial acetic acid (anhydrous, 100% purity) was purchased from Merck KGaA (Darmstadt, Germany). For dissolving Gelatin and chitosan powders in addition to acetic acid, distilled water is also applied. All these bio-based polymers and solvents are used without additional physical and/or chemical treatments.

2.2 Methods

2.2.1 Hydrodistillation of eucalyptus

Eucalyptus leaves were subjected to extraction for 2 h using a steam still equipped with a Clevenger cooling apparatus. The resulting organic phase was separated using a separatory funnel and subsequently dried with anhydrous sodium sulfate. The isolated eucalyptus essential oil (EEO) was then stored in an amber bottle at + 4 ºC.

Composition analysis of EEO was conducted using a gas chromatograph-mass spectrometer (GC–MS) system. The exact equipment used was the Thermo Scientific Trace 1310 gas chromatograph paired with the ISQ Single Quadrupole mass spectrometer, manufactured by Thermo Fisher Scientific in Austin, TX, USA. Separation of components was done using a Thermo TG-WAX-MS column (0.25 mm ID × 60 m length, 0.25 µm film thickness). The carrier gas used was helium, flowing at a rate of 1.5 mL/min. The starting oven temperature was set at 60 °C and steadily raised to 230 °C at a rate of 4 °C/min, maintaining the initial and final temperatures for 6 and 15 min, respectively. The MS transfer line and ionization temperature were maintained at a constant value of 250 °C. Component identification was conducted via Xcalibur software, employing mass spectra references from Wiley 9, NIST, and Mainlib databases.

2.2.2 Production of nanofibrous webs

G solution was prepared by dissolving 15 wt.% of pure gelatin with 85 wt.% of acetic acid. The mixture was then placed on a magnetic stirrer and stirred for 8 h until a homogenous solution was prepared. On the other hand, for preparing G-C solution 12 wt.% of gelatin, 3 wt.% of chitosan, and 85 wt.% of acetic acid were taken into consideration and stirred with a magnetic stirrer at a temperature of 60 °C for up to 8 h. Finally, the EEO-added G-C solution follows a similar procedure to G-C methods except in G-C-EEO solutions there is an addition of EEO with 0.75 wt.%. During the production process of G, G-C, and G-C-EEO fiber webs by an E-B method, as schematically represented in Fig. 1, the production of nanofibers involved the seamless integration of air pressure and an electric field to facilitate the propulsion of the solution. Highly pressurized air at 1.5 bar was delivered by an air compressor to drive the G-C solution. The solution’s controlled flow rate of 10 ml/h was managed by a syringe pump, and an electric voltage of 15 kV was applied at the nozzle’s tip to enhance spinnability and reduce the occurrence of fiber bundles. This orchestrated process led to the creation of nanofibers. The solution was propelled from the nozzle tip under the combined influence of air pressure and the electric field. As the fibers traveled a distance of 40 cm from the nozzle tip to a rotating collector, solvent evaporation occurred, resulting in nanofibers with varying fiber morphologies and diameters. The disparities in diameter were attributed to the solution concentration. Likewise, the same process is employed to fabricate nanofibers from both the G and G-C-EEO solutions.

Fig. 1
figure 1

Schematic diagram of electro-blowing method

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G, G-C, and G-C-EEO nanofibers are weak in their mechanical properties and are hydrophilic. To enhance their mechanical strength, and increase the hydrophobicity of the fabricated nanofibers meshes to use them for active food packaging and wound dressing applications, thermal crosslinking was applied on the nanofibers at a temperature of 140 °C for 4 h. By using a Protherm furnace, this step is very crucial to ensure the produced nanofibers possess the necessary attributes for successful food and wound dressing applications. Thermal cross-linking on nanofibers was chosen over chemical crosslinking due to its non-toxicity, which promotes efficient wound healing while maintaining patient comfort and safety (Fig. 2).

Fig. 2
figure 2

Thermally crosslinked samples

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2.2.3 Characterization of nanofibrous webs

Methods of characterization and biological properties of nanofibrous webs are given in supplementary material.

3 Results and Discussion

3.1 Characterization of EEO

The investigation of Eucalyptus Essential Oil (EEO) using Gas Chromatography-Mass Spectrometry (GC–MS) showed that it is made up of 16 different components, which together make up 97.8% of the total oil content (Table 1). The primary ingredients, namely 1,8-Cineole (49.8%), β-Pinene (16.7%), and α-Pinene (10.8%) play significant roles in determining the particular character of EEO. The prevalence of 1,8-Cineole, sometimes referred to as eucalyptol, greatly influences the fragrance and provides considerable medicinal properties to the essential oil [35]. Various research has emphasized the antioxidant ability of 1,8-Cineole, ascribing its capability to counteract free radicals and alleviate oxidative stress [36, 37]. Additionally, the primary components, β-Pinene and α-Pinene, have outstanding antibacterial capabilities, strengthening the attraction of EEO for applications in both food packaging and wound dressing, where protection against microbial development is crucial [38]. The main components of EEO are identified, along with many minor constituents such as α-Phellandrene, p-Cymene, trans-Pinocarveol, and others. Each of these small ingredients adds to the complex and subtle scent of EEO. This sophisticated combination not only increases the olfactory richness but also widens the possible uses of EEO in numerous sectors [3]. The collective impact of these components emphasizes the adaptability of EEO, placing it as a prospective choice for varied applications, ranging from medicinal formulations to new materials. Briefly, the main and small ingredients combined contribute to the multidimensional aspect of EEO, making it an attractive topic for investigation in the fields of both conventional medicine and modern materials science.

Table 1 Composition of eucalyptus essential oil
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3.2 SEM morphologies and fiber diameters

Figure 3 shows the SEM morphologies and fiber diameter distribution of G, G-C, and G-C-EEO nanofibers examined by scanning electron microscope. As displayed in the Figure beadles and droplet-free nanofibers were able to be fabricated for all samples. Here, in the figure, the red lines accurately represented the log-normal curves, which provided the best fit for the fiber diameter distributions. Compared to all samples, G had the highest average fiber diameter (AFD) value of 334.8 ± 9.56 nm, given that gelatin is a bigger molecule, and hence, these findings make sense. Compared to other studies such as Siqueiros et al., also reported that pure G had the highest fiber diameter values compared to the sample diameter spun after the addition of chitosan solution [39]. For G-C fibers fabricated from G-C solution, the incorporation of C into G results in a reduction in AFD attributed to a decrement in the viscosity of the solution. As a result, a mean fiber diameter of 258.92 ± 2.34 nm was investigated for the G-C filter web and compared to G this is a remarkable reduction in fiber diameter as witnessed. Similarly, by adding EEO to the G-C solution the nanofibers sample spun from the G-C-EEO solution, presented good morphological characteristics together with an AFD of 260.39 ± 5.05 nm. Generally, a discernible trend of decreasing fiber diameters was observed with C and EEO addition to pure G. This result was corroborated in research work by Elbhnsawi et al. [31]. In their study, it was indicated that decreased fiber diameters were noticed by adding chitosan and eucalyptus oil concentrations into the solution. In another study by Abdulkadhim and Habeeb, it was found that when the concentration of chitosan increased inside the gelatin solution it was observed that the nanofiber diameter of the blend reduced [40]. In addition, Fei et al. [41] conducted a study that aligns with our findings. Their research also revealed that the inclusion of polyphenols extracted from tea led to a reduction in fiber diameter as a result of decreased solution viscosity.

Fig. 3
figure 3

SEM morphologies of nanofibrous webs. a G, b G-C, c G-C-EEO

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3.3 Air Permeability

The air permeability characteristics play a pivotal role in proper air circulation, which is essential for preventing moisture accumulation and promoting the healing process. The air permeability test results of each nanofibrous sample are depicted below in Fig. 4. Studies expressed that fibrous sample’s air permeability properties are influenced by different parameters such as nanofibrous web thickness, fiber diameter, basis weight, density, and porosities [42]. The fiber diameters are lesser as revealed by SEM examination for G-C and G-C-EEO as compared to pure G, the air permeability becomes lower attributed to the decrement in the porosity between fibers. Generally, nanofibrous webs with better air permeability properties are vital for wound healing applications [43]. Here, the air permeability values for the electro-blown nonwoven fabrics G, G-C, and G-C-EEO were measured as 17.67, 14.33, and 13.33 mm/s, respectively. The presence of encapsulated EEO in the G-C nanofibrous networks resulted in a tortuous path for gas molecules. Consequently, there was a slight reduction in the air permeability of G-C-EEO in comparison to G and G-C. This anticipated outcome was confirmed by the testing results as indicated in the figure. On the contrary, looking at the food packaging perspective having strong air barrier properties can significantly extend the shelf life of food [44]. Therefore, the G-C-EEO samples exhibit a slightly lower level of breathability compared to G but hold great promise for its advancement to be used for wound dressing material. Additionally, this sample is an ideal choice for active food packaging in comparison to G and G-C samples.

Fig. 4
figure 4

Air permeability of nanofibrous webs

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3.4 FTIR spectra of nanofibrous webs

The FTIR spectra of G, G-C, and G-C-EEO are illustrated in Fig. 5a. Notably, the FTIR spectrum of G nanofibers showed a signal peak at 3286 cm−1, attributed to the stretching vibration of the OH and N–H groups (amide A) accompanied by hydrogen bonding [39, 45]. Similar FTIR spectra peaks due to amide group (N–H) stretching were noticed at wavenumber 3300 cm−1 in Campa et al., [39]. The peaks noted at 1640 cm−1 wavenumber, known as the amide I band, linked to the stretching vibration of the C = O bond could be due to the presence of both random coil and α-helix conformations in gelatin [46, 47]. Further, it was observed that there exist great resemblances in the FTIR signal peaks of the G-C and G-C-EEO samples, which is because of the encapsulation of EEO within the nanofibers. The G-C and G-C-EEO blends contain sharp peaks of both gelatin at 1640 cm−1 and chitosan at 1079 cm−1. These peaks serve as evidence for the presence of both gelatin and chitosan on the surface of the blends [48]. Therefore, the FTIR spectra of G-C and G-C-EEO display characteristic peaks at 3286 cm−1, 1079 cm−1, and 1640 cm−1 corresponding to the stretching vibration of O–H, -C–O–C- bonds, and amid I, respectively [48].

Figure 5
figure 5

a FTIR spectra and b Thermal properties of nanofibers webs

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3.5 TGA analysis of nanofibrous webs

TGA thermograms of G, G-C, and G-C-EEO samples are displayed in Fig. 5b. The thermal analysis of all nonwoven nanofibers exhibits a degradation process that occurs in two distinct steps. Sample G presents a first weight loss that occurs in the temperature range of 100–154 °C with approximately 11.31%, which is most likely the result of moisture evaporation [39]. In addition, a second stage weight loss at a temperature between 250 to 400°C with 54.86% was observed, which is significant weight loss resulting from protein degradation [14, 39]. In contrast, when examining G-C samples, it was observed that the samples exhibited a moisture release between 80 and 154°C, resulting in an initial weight loss of nearly 12.26%. Additionally, a subsequent weight loss of around 48.33% was recorded at temperatures ranging from 250–400°C. The second stage of thermal degradation of G-C-EEO was observed through TGA analysis, occurring within the temperature range of 250 to 400 °C. This resulted in a weight loss of around 50.42%. Consequently, the TGA analysis demonstrated that the inclusion of C and EEO into G (G-C-EEO) mitigates thermal degradation, thereby maintaining its thermal stability. This is in contrast to the elevated thermal degradation observed in G-based nanofibrous samples.

3.6 Water Contact angle analysis

Hydrophobicity/hydrophilicity tests were conducted for each fibrous web sample, and their WCA values are demonstrated in Fig. 6. The measured WCA values for G, G-C, and G-C-EEO samples were 55 ± 1.52°, 38 ± 1.52°, and 30 ± 0.96°, respectively. Despite the WCA being less than 90° for all samples, the comparison among them indicates that G samples possess relatively hydrophobic surfaces in contrast to G-C and G-C-EEO. The cause for this is that the properties of the G-C and G-C-EEO blend samples are well known by the abundance of hydrophilic groups within the molecules of gelatin and chitosan, such as amine and carboxyl. As a result, the hydrophobic characteristics of fibrous webs decrease with chitosan addition to the gelatin morphology, leading to lower contact angles. Similar results were also reported in the research work of Qian et al. [49]. In their study, it was revealed that a decrease in the contact angles of the blended nanofiber mats. Specifically, the contact angle of pure polycaprolactone (PCL) nanofibers decreased from 128° to 69°, 60°, and 28° as the percentages of CS-Gel increased to 25%, 50%, and 75%, respectively. Other studies by Dayisoylu et al. [14] and Zadeh et al. [50] found that with an increment addition of grapevine leaf extract (GLP) content into gelatin, as well as the higher incorporation of date palm polyphenol onto polylactic acid (PLA), resulted in a decrease in the WCA, respectively.

Fig. 6
figure 6

Contact angle results for nanofibrous webs

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3.7 Mechanical properties

It is crucial to analyze the mechanical properties of nanofibrous web samples to determine their suitability for long-term and uninterrupted usage. The tensile strength and elongation characteristics of the G, G-C, and G-C-EEO nanofiber webs are investigated. The findings are elucidated in Fig. 7, providing a clear understanding of the results.

Fig. 7
figure 7

Tensile test results of G, G-C, and G-C-EEO nanofibrous web samples

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Figure 7 demonstrates that the addition of chitosan to gelatin (G-C) resulted in an increment in both tensile strength and elongation ratio as compared to the G sample. This increment in tensile strength and elongation ratios following the addition of chitosan is likely attributed to the enhancement of structural integrity within the nanofiber matrix. Chitosan, being a robust polysaccharide, acts as a reinforcing agent, strengthening the nanofibers. The improved cohesion between gelatin and chitosan, along with potential intermolecular interactions, contributes to the overall reinforcement effect, resulting in higher tensile strength and increased elongation ratios.

Furthermore, the impact of EEO on the characteristics of gelatin-based nanofibers, specifically in terms of elongation and tensile strength, presents fascinating observations. The tensile strength and elongation at the break decreased after adding EEO into the G-C blend. This is due to the disruption of the polymer structure within the nanofiber matrix. EOs, known for their volatile nature, can alter the solvent properties of the solution, affecting the spinning process and leading to reduced tensile strength. Additionally, the complex composition of EEO may introduce incompatibilities with gelatin, disrupting the alignment and packing of polymer chains and, consequently, a decrease in both tensile strength and elongation ratios. These results were in complete agreement with previous studies by Kharazian and Vasafi [51].

3.8 Antioxidant activity

The antioxidant activity data obtained from the DPPH and ABTS tests provide insights into the improved antioxidant capacity achieved by adding EEO to the gelatin-chitosan nanofibers (Table 2). The samples had unique antioxidant capabilities, highlighting the impact of EEO components on the total effectiveness. Gelatin itself has bioactive peptides that contribute to its antioxidant action [52]. Chitosan, being a polysaccharide produced from chitin, exhibits intrinsic antioxidant qualities owing to its chemical structure, comprising amino and hydroxyl groups [53]. However, when gelatin is combined with chitosan, the resultant composite frequently demonstrates improved antioxidant capacity. This phenomenon has been demonstrated in several studies where the combination of gelatin and chitosan leads to a synergistic impact on antioxidant capabilities [54]. Firstly, with regards to the DPPH test, the G-C-EEO sample exhibited a significantly elevated antioxidant activity, with a percentage inhibition of 76.9 ± 5.8%. The significant increase in antioxidant capacity, as compared to G (8.2 ± 1.2%) and G-C (22.7 ± 4.3%), indicates a synergistic impact arising from the inclusion of EEO components. Significantly, the primary constituents of EEO, namely 1,8-Cineole (eucalyptol), β-Pinene, and α-Pinene, have previously been linked to potent antioxidant characteristics. The inclusion of these constituents in the G-C-EEO sample may substantially contribute to the observed elevated DPPH radical scavenging activity. Similarly, the ABTS test showed the same pattern. The G-C-EEO sample had a significant ABTS radical scavenging activity of 85.1 ± 7.2%, outperforming both G (12.3 ± 1.3%) and G-C (34.9 ± 4.9%). This highlights the increased ability of the nanofiber matrix to neutralize ABTS radicals due to the incorporation of EEO. The combined antioxidant capacity of the main EEO components, namely 1,8-Cineole, which is recognized for its effective ability to neutralize free radicals, is likely a substantial factor in the reported outcomes. The results of this research correspond closely with those published by Bertolo et al. [55]. Bertolo et al. similarly noticed an improvement in the antioxidant activity of gelatin and chitosan films when functionalized with pomegranate peel extract. This uniformity in findings emphasizes the stability of the reported synergistic effects of gelatin, chitosan, and natural extracts across numerous experiments. However, it is notable that the solvent casting process adopted by Mirella et al. could face issues for large-scale manufacturing owing to its labor-intensive nature. In contrast, our research employed the 3D quickly created electro-blown process, enabling a more efficient and scalable methodology. This contrast in manufacturing processes not only addresses practical problems for possible large-scale applications but also stresses the flexibility and versatility of gelatin-chitosan composites for varied usage, such as in food packaging and wound treatment. The electroblown process, with its quick and scalable manufacturing capabilities, provides a potential path for the translation of these functionalized materials into practical applications.

Table 2 Antioxidant and antimicrobial activity of nanofibers
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3.9 Antimicrobial activity

The antibacterial activity findings indicate an increase in inhibition zones for both S. aureus and E. coli with the introduction of EEO into the Gelatin-Chitosan composite (Fig. 8). Chitosan, a well-known antibacterial agent, contributes to the early antimicrobial activity detected in the G-C sample. Chitosan’s antibacterial capabilities are linked to its polycationic composition, which may damage microbial cell membranes, resulting in cell death [56]. The improved antibacterial activity in the G-C-EEO sample may be related to the antimicrobial components discovered in EEO, such as 1,8-Cineole, β-Pinene, and α-Pinene. These components have been described in the literature for their antibacterial properties [57]. Notably, 1,8-Cineole has proven antibacterial action against several diseases [58]. The combination of chitosan’s innate antimicrobial capabilities with the bioactive chemicals from EEO likely contributes synergistically to the enhanced inhibition zones found in the G-C-EEO sample. The differential susceptibility of E. coli and S. aureus may be linked to their Gram-negative and Gram-positive bacterial cell wall architectures, respectively [59]. Gram-negative bacteria like E. coli contain an outer membrane that functions as an extra barrier, making them more resistant to antimicrobial treatments compared to Gram-positive bacteria like S. aureus. The outer membrane of Gram-negative bacteria includes lipopolysaccharides that build a more complicated and protective structure. This outer membrane hinders the entry of antimicrobial drugs, leading to E. coli’s relative resistance compared to S. aureus [60]. Antimicrobial activity is vital in wound dressings to prevent and cure infections. Wounds are prone to bacterial colonization, which may delay the healing process. Antimicrobial wound dressings assist provide a sterile environment, minimizing the risk of infection and facilitating speedier healing. The found antibacterial activity in the G-C-EEO sample supports its possible use in wound dressings, where the combination of chitosan and EEO components might give efficient protection against a wide range of microorganisms. Antimicrobial activity is equally essential in food packaging to increase the shelf life of goods and assure food safety. The inclusion of antimicrobial compounds in packaging materials helps suppress the development of spoilage germs and diseases, protecting the quality and safety of the packed food. The antibacterial capabilities of the G-C-EEO composite make it a suitable choice for food packaging applications, delivering an extra layer of protection against microbial contamination during storage and transit. This is especially helpful in the context of assuring food quality and lowering the risk of foodborne infections.

Fig. 8
figure 8

Antimicrobial activity of nanofibers on S.aureus and E.coli

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3.10 Biodegradation

The degradability of the produced nanofibers was evaluated over 30 days using the soil burial method, as shown in Fig. 9. These nanofibers primarily degrade through hydrolysis, where water plays a crucial role. Water molecules present in the soil and on the material surface facilitate the growth of microorganisms that contribute to the degradation of polymer films. Hydrolysis occurs when the polymer backbone breaks down by forming hydrogen bonds with water molecules, resulting in smaller fragments. Hydrophilic chemicals in the coating material further accelerate this breakdown process [52]. The degradation rates varied based on the composition and intrinsic properties of each nanofiber. Nanofibers made solely of gelatin degraded significantly within 20 days, whereas those containing both gelatin and chitosan exhibited partial degradation. This slower degradation is due to the hydrogen bonds between gelatin and chitosan and the antimicrobial properties of chitosan. After 30 days, the nanofiber without essential oil was largely degraded, while the sample containing essential oil showed only partial deformation, indicating prolonged degradation. This slower degradation is likely due to the strong antibacterial properties of the G-C-EEO sample, which inhibit the activity of degrading microorganisms. These findings demonstrate that the synthesized nanofibers are a viable alternative to synthetic packaging materials due to their biodegradability. This makes them suitable for sustainable packaging solutions, contributing to a reduction in environmental impact.

Fig. 9
figure 9

Soil degradation of G, G-C, and G-C-EEO nanofibrous web samples

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4 Conclusion

In conclusion, this study delves into the innovative fabrication of nanofiber webs designed for applications in wound dressing and food packaging. The incorporation of gelatin, chitosan, and EEO in the electro-blowing method for nanofiber production presents a novel approach, addressing challenges associated with conventional methods like electrospinning, solution blowing, and centrifugal spinning. The resulting nanofiber webs exhibit promising morphological characteristics, including reduced fiber diameters and air permeability, and enhanced thermal stability. The inclusion of chitosan and EEO serves to overcome limitations associated with gelatin, providing improved mechanical properties, antibacterial efficacy, and potential wound healing and food packaging attributes. The combination of gelatin and chitosan contributes to biodegradability and biocompatibility, essential for creating wound dressings or food packaging materials compatible with the natural environment. Moreover, the addition of EEO introduces an extra layer of antimicrobial protection, aligning with sustainability goals in wound care or active food packaging. A comprehensive analysis covering SEM morphologies, fiber diameters, air permeability, FTIR spectra, TGA thermograms, and contact angle measurements establishes a thorough understanding of the fabricated nanofiber webs’ characteristics. While the developed nanofiber webs show great potential for wound healing or food packaging applications compared to currently utilized materials due to their favorable properties summarized as follows,

  • The newly developed G-C-EEO material does not adhere to the wound, ensuring the right level of moisture without causing harm to the surrounding area when removed;

  • Having a robust air barrier is crucial when considering food packaging. It plays a vital role in prolonging the shelf life of food. Therefore, G-C and G-C-EEO exhibit strong potential as suitable options for both wound dressing and food packaging purposes; and

  • The G-C-EEO nanofiber-based material produced in this research is hydrophilic (30 ± 0.96°), making it ideal for wound dressing purposes due to its ability to release antibacterial and/or other therapeutic agents that are incorporated into it.

Moreover, it is essential to note that the incorporation of EEO led to a decrease in tensile strength and elongation ratios. This observation underscores the need for further optimization and fine-tuning of the formulation to balance antimicrobial benefits with mechanical properties. In comparison to existing studies, this research stands out for its unique combination of gelatin, chitosan, and EEO, contributing to the advancement of nanofiber technology. The findings not only expand knowledge in the field but also pave the way for the development of advanced wound dressing or food packaging materials with enhanced therapeutic properties. Overall, this study marks a significant stride in the pursuit of effective and innovative solutions for wound healing or food packaging.

5 Declaration of Generative AI and AI-assisted Technologies in the Writing Process

During the preparation of this work, the authors used ChatGPT 3.5 to improve language and readability. After using this tool/service, the authors reviewed and edited the content as needed and took full responsibility for the content of the publication.