Electrospun PCL membranes for localized drug delivery and bone regeneration

Abstract

Background

Bone loss caused by cysts, tumors, trauma, and other factors is a significant challenge in medicine and dentistry. Effective bone regeneration is essential for accelerated healing and improved bone volume. While systemic drug supplementation helps, local delivery through gbr/gtr membranes is preferred for targeted treatment with minimal systemic effects. This study aims to develop drug-loaded gbr membranes using electrospinning to enhance localized drug delivery and tissue regeneration.

Methods

Polycaprolactone (PCL) membranes were produced via electrospinning with various concentrations and solvent ratios. Therapeutic agents—pentoxifylline, carrageenan, and sodium fluoride—were incorporated into the membranes. Morphological analysis was performed using scanning electron microscopy (SEM), mechanical properties were assessed through tensile testing, structural characterization was done via Fourier-transform infrared spectroscopy (FTIR), and thermal properties were evaluated with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Drug release behavior was studied using UV-Vis spectrophotometry.

Results

SEM revealed optimal fiber morphology in membranes with 10% PCL and 1% pentoxifylline, 0.5% NaF, and 1% carrageenan. Tensile strength was highest in 10% PCL membranes (2.5 MPa), outperforming 12% PCL (1.8 MPa). FTIR and TGA confirmed successful drug incorporation and thermal stability, with decomposition temperatures ranging from 395 °C to 510.9 °C. UV-Vis showed effective drug release, with 2% pentoxifylline achieving the highest release at 2 h (34%) and 4 h (62%), demonstrating enhanced performance for localized drug delivery.

Conclusions

PCL-based electrospun membranes with therapeutic agents were successfully developed, exhibiting promising characteristics for localized drug delivery and tissue regeneration. These membranes showed comparable mechanical properties to commercial GBR/GTR membranes. Future research should focus on optimizing formulations and evaluating clinical efficacy.

Background

Bone loss due to cysts, tumors, trauma, inflammatory, and infectious diseases is a significant concern in both medicine and dentistry. Enhancing the natural healing process of bone tissue, which is rich in cellular activity, is a primary goal to accelerate healing and increase new bone volume. Systemic supplementation of drugs that positively affect bone regeneration is often included in treatment protocols. However, achieving adequate drug concentration in the target tissue requires considering the body’s metabolism and meticulously adjusting the dosage. To mitigate many of these disadvantages, local application of supportive drugs is preferred. This approach aims to deliver the drug directly to the target area with a much lower dose and minimal systemic effect compared to systemic administration.

Guided bone regeneration (GBR) and guided tissue regeneration (GTR) membranes are new-generation biomaterials used to heal damaged areas in bone and other tissues and create new tissues in areas with insufficient tissue volume. In GBR, the focus is on increasing bone tissue density rather than regenerating soft tissues in the healing area. The primary function of GBR/GTR membranes is to act as a barrier between the adjacent connective tissue and the bone defect area, preventing the migration of non-osteogenic cells into this region [1, 2]. Additionally, like various wound dressing materials, they help create a stable environment during the wound healing process and aid in preventing potential infections [3].

Recent advances in biotechnology have integrated barrier membranes into the routine treatment protocols of periodontologists and maxillofacial surgeons for tissue regeneration. Current efforts focus on developing new biodegradable membrane biomaterials that can be applied in surgical interventions without requiring a second surgical procedure for removal. Synthetic GBR/GTR membranes, which can be easily obtained in the laboratory using glycolic acid, lactic acid, and various solvent materials, are still under development.

The electrospinning technique involves forming very fine fibrous structures by subjecting pre-prepared polymer solutions to a high electrostatic field, resulting in separation and thinning. This technique can produce fibrous membranes for surgical concepts using biocompatible polymer solutions. One of the main advantages of electrospinning is its ability to create nanometer-sized fibers that support cell organization in damaged tissue. The porous structure it creates allows for the release of drugs that can aid in tissue regeneration. Thus, an additional function of drug delivery can be assigned to barrier membranes expected to provide guided bone regeneration.

This study aimed to develop drug-carrying barrier membranes for use in oral surgical procedures using the electrospinning method. The therapeutic agents identified for this study include pentoxifylline, used to increase blood circulation and tissue nutrition in surgical interventions [4, 5]; carrageenan, considered to have antibacterial properties in surgical procedures involving the oral region [6, 7]; and sodium fluoride, a standard component in treatment protocols to strengthen the crystalline structure of bone tissue [8]. The study involves the production, testing, and analysis of samples containing these three therapeutic agents, which are believed to positively contribute to bone tissue regeneration.

The inclusion of all three drugs—pentoxifylline, carrageenan, and sodium fluoride—was based on their complementary mechanisms of action, each addressing distinct aspects of the healing process. Pentoxifylline enhances blood flow and tissue oxygenation, critical for effective healing. Carrageenan provides antibacterial properties, reducing the risk of infection in surgical sites, which is paramount for successful recovery. Sodium fluoride plays a vital role in bone remineralization, directly contributing to the structural integrity of newly formed bone. By combining these agents, the study aims to create a multifaceted approach to enhance localized bone regeneration, providing synergistic effects that could significantly improve outcomes in surgical procedures.

In the first step of the study, solutions with different concentrations were prepared, and solid membrane forms were created from these solutions using various parameters in the electrospinning device. Subsequent steps involved the characterization and analysis of these synthetic membranes.

The importance of this work lies in inclusion of pentoxifylline, carrageenan, and sodium fluoride into PCL electrospun membranes for the first time, aimed at enhancing localized bone regeneration. There is a gap in the literature regarding the using of these therapeutic agents in different needs. This study addresses this gap by developing multi-functional membranes that not only supports bone regeneration but also provides antibacterial effects and strengthens bone tissue. This novel approach is expected to contribute significantly to the field of guided bone regeneration and could pave the way for new therapeutic strategies in maxillofacial surgery.

Methods

Materials

The primary material used for the membranes in this study was polycaprolactone (PCL) with a molecular weight (Mw) of 80,000 g/mol (Sigma/Aldrich, Burlington, Massachusetts, United States). Dimethylformamide (DMF) of extra purity (ISOLAB, Wertheim, Germany) and chloroform suitable for liquid chromatography (ISOLAB) were used as solvents to dissolve PCL. The drugs incorporated into the carrier membranes were solid pentoxifylline (Sigma/Aldrich), carrageenan suitable for gel preparation (Sigma/Aldrich), and sodium fluoride in liquid form (Sigma/Aldrich).

Phosphate-buffered saline (PBS) solution (pH 7.4) was obtained from Gunduz Kimya (Istanbul, TURKEY) for the UV-vis device to determine release behavior. The references for materials were sourced from Sigma/Aldrich and ISOLAB.

Preparation of solutions

In this study, four different solutions were prepared without drugs at two different solvent percentages (9:1 and 6:4) and two different PCL concentrations (12% and 10%). All solutions were homogenized using a magnetic stirrer. Next, the drugs to be loaded onto the membranes were reduced to specific sizes using mechanical grinders. Quantities of 0.5 g, 1 g, and 2 g were weighed and added to the solutions, and a homogeneous structure was formed.

Electrospinning process

In the electrospinning process, drug-loaded solutions were sprayed from the injector to the collector plate under high electric current and a nanofiber structures were formed. Using these solutions, eight mats were created in the electrospinning device (Inovenso, NS24XP) with voltage values of 20 kV and 25 kV. Subsequently, structural analyses identified that mats 4 and 8, containing 10% PCL, were most suitable for drug delivery, and their parameters were selected for further experiments. Due to the high viscosity of drug-loaded solutions, homogeneous mats could not always be formed on the collector plate. In such cases, the electrospinning process was repeated with 30 kV and 35 kV electric voltage.

Morphological analysis

The morphological properties of the samples were examined using a field emission scanning electron microscope (Fei, Quanta 450 FEG). Equal-sized samples were cut from the nanofiber membranes and coated with gold-palladium under argon gas for 40 s. The device was set to low vacuum mode using a Low Vacuum Detector. Images were taken at 1 nm and 100 μm magnifications, and morphological analyses were performed.

Mechanical analysis

The second analysis method was a tensile test to determine mechanical strength. Samples were prepared by cutting them into dimensions of 1 × 4 cm. The tensile-compression testing device (Devotrans, DVT UZM K3) was set to a pulling speed of 5 mm/min. The tensile tests were repeated three times for each sample, and arithmetic means were recorded.

Structural analysis

In the third step, Fourier-transform infrared spectroscopy (FTIR) was used for structural analysis. This device (Tetra, Jasco 6600) was employed to examine the integration and chemical bonding of PCL, pentoxifylline, carrageenan, and sodium fluoride in the membranes. Comparative morphological analyses resulted in selecting one membrane from each drug group. The presence of functional groups in the selected nanofiber membranes was determined in the wavelength range of 400–4000 cm^− 1. The FTIR spectra were recorded at room temperature, with background subtraction and baseline adjustments. This process confirmed the presence of drugs in the nanofiber membranes and the feasibility of obtaining polymer-drug composite materials.

Thermal analysis

Thermal analyses of the membranes were performed using a thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC). For TGA, nanofiber membranes were weighed at 1.5 mg, and for DSC analysis, at 2 mg. The TGA (Hitachi, STA 7200) device operated at a heating rate of 10 °C/min in a nitrogen atmosphere, with a temperature range of 25 °C to 500 °C. TGA analyzed the purity and degradation behavior of the samples. Subsequently, the DSC device (Hitachi, 7000X) operated at a heating rate of 10 °C/min in a nitrogen atmosphere, with a temperature range of -70 °C to 150 °C. This analysis determined the glass transition temperature (Tg), melting point (Tm), and enthalpy (ΔH) values of the samples.

Drug release detection

For drug release detection, 1 × 1 cm sections were cut from the nanofiber membranes and placed in test tubes. The tubes were numbered, and 6 ml of PBS solution was added to each tube at 90-second intervals. The test tubes were incubated in a shaking water bath at 37.5 °C and 105 rpm for 4 h. Subsequently, the test tubes were placed in a UV-vis spectrophotometer (Jasco, V-750), set to a range of 900–190 nm. Absorbance values were set to 206 nm for pentoxifylline and 201 nm for sodium fluoride and carrageenan. Drug release at 2-hour and 4-hour intervals for each sample was recorded, considering 90-second intervals.

Results

Morphological (FEGSEM) analysis results

The morphology of 26 membranes produced via electrospinning was examined using scanning electron microscopy (SEM). The SEM images of the membranes were also used to determine the diameters of the fibers within the membranes.

SEM images of drug-free membranes with a chloroform-DMF ratio of 9:1 revealed severe buckling in the fibers of the first three membranes. However, the SEM image of the fourth membrane displayed a homogenous appearance with parallel fibers, which were deemed ideal for the production of drug carrier membranes (Fig. 1).

Fig. 1

SEM images of 10% PCL (A), 10% PCL-1% Pentoxifylline (B), 10% PCL-0.5% NaF (C) and 10% PCL-1% Carrageenan (D) membranes at 1000x magnification

The second group of drug-free membranes, with a chloroform-DMF ratio of 6:4, included the 5th, 6th, 7th, and 8th membranes. Although the number of thin fibers increased with the reduction of the chloroform ratio and higher electric current, a homogenous and parallel appearance similar to the fourth membrane was not observed. Instead, areas of accumulation, angularity between fibers, knots, and wavy fibers were seen. The eighth membrane exhibited the most desirable morphological characteristics within this group.

For the other 18 membranes produced using the parameters of the 4th and 8th membranes, both the morphological structures of the fibers and the accumulation levels of pentoxifylline, carrageenan, and sodium fluoride within the fibers were examined. SEM images indicated that the maximum loadable drug doses to avoid accumulation areas were 1% pentoxifylline, 0.5% sodium fluoride, and 1% carrageenan (Fig. 1).

The fiber diameters were measured using the ImageJ program, and the diameter distribution was evaluated. The SEM images of 10% PCL nanofiber membranes revealed random fiber orientations and a rough surface morphology due to the solvent. Composite nanofiber membranes with 1% pentoxifylline had wider fiber diameters compared to drug-free membranes. In contrast, the sample with 0.5% NaF showed narrower average fiber diameters but deeper roughness compared to pentoxifylline-containing membranes. The 10% PCL-1% carrageenan membrane exhibited significant diameter reduction compared to pentoxifylline and NaF-containing membranes, leading to an increased surface area, which correlated with improved mechanical properties observed in tensile tests. As expected, the elasticity of the nanofiber membrane increased proportionally with the surface area.

Mechanical analysis (tensile test) results

Tensile test results showed that 10% PCL nanofiber membranes had superior mechanical properties compared to 12% PCL membranes. The elongation values of the membranes increased in parallel with the tensile strength, which can be explained by the increased brittleness of the mats due to the higher PCL content. The increase in PCL concentration made the mats more brittle by reducing their flexibility. Among the 10% PCL samples, nanofiber membranes produced with a 90/10 chloroform/DMF ratio had better mechanical properties than those with a 60/40 chloroform/DMF ratio.

As the voltage applied to the polymer solutions increased, a structure with tightly packed fibers and a larger surface area was formed, resulting in improved mechanical properties. Furthermore, higher electric current values led to higher elongation values in the membranes.

Drug carrier membranes with a 90/10 chloroform/DMF ratio and 10% PCL concentration (containing 0.5%, 1%, and 2% pentoxifylline) showed better mechanical resistance and elongation than those with a 60/40 chloroform/DMF ratio. Higher pentoxifylline concentrations improved mechanical properties in the 10% PCL solutions. However, in systems with a 60/40 chloroform/DMF ratio, increasing the pentoxifylline concentration from 0.5 to 1% improved mechanical properties, while a 2% pentoxifylline concentration reduced tensile strength but increased maximum elongation.

For sodium fluoride carrier membranes with a 60/40 chloroform/DMF ratio and 10% PCL concentration (containing 0.5%, 1%, and 2% sodium fluoride), higher tensile strength and maximum elongation were observed compared to membranes with a 90/10 chloroform/DMF ratio. As the sodium fluoride concentration increased, tensile strength increased while elongation values decreased, indicating that sodium fluoride increased the stiffness of the membrane structure while reducing elasticity.

Lastly, carrageenan carrier membranes with a 60/40 chloroform/DMF ratio and 10% PCL concentration (containing 0.5%, 1%, and 2% carrageenan) showed higher tensile strength and maximum elongation than membranes with a 90/10 chloroform/DMF ratio. Higher carrageenan concentrations led to a decrease in mechanical durability, while maximum elongation values remained unchanged.

Structural characterization (FTIR analysis) results

The structural characterization of the nanofiber membranes produced by electrospinning was performed using an FTIR device with a wavelength range of 400–4000 cm^− 1. Based on the percent transmittance (%T) values, the specific bonds and bands present in the samples were identified.

The PCL structure displayed C-H stretching bands at 2940–2857 cm^− 1 and a characteristic absorption band for the carbonyl group (C = O) at approximately 1721 cm^− 1. C-O stretching bands were observed at 1238 cm^− 1 and 1162 cm^− 1. The pentoxifylline spectrum exhibited characteristic bands for C-H, C = O, and amide C = O stretching at 3120 − 2944, 1715, and 1695–1545 cm^− 1, respectively. Specific bands unique to pentoxifylline, such as the = C-H band at 3120 cm^− 1 and amide bands at 1695–1545 cm^− 1, were identified in the comparative spectrum. The spectra of the samples are shown in Fig. 2.

Fig. 2

FTIR spectra of 10% PCL-1% Pentoxifylline (A), 10% PCL-0.5% NaF (B) and 10% PCL-1% Carrageenan (C) membranes

The PCL structure displayed C-H stretching bands at 2940–2857 cm^− 1 and a characteristic absorption band for the carbonyl group (C = O) at approximately 1721 cm^− 1. C-O stretching bands were observed at 1238 cm^− 1 and 1162 cm^− 1. Monofluorinated compounds exhibited strong bands at 1100–900 cm^− 1, corresponding to C–O–C and C–F stretching vibrations. Additionally, increased intensity in the fingerprint region supported composite formation.

Specific bands for carrageenan were identified at 1638 cm^− 1 and 1378 cm^− 1. Bands for PCL were observed at 2940–2861 cm^− 1, 1721 cm^− 1, 1239 cm^− 1, and 1163 cm^− 1. The spectrum of the 10% PCL-1% carrageenan nanofiber membrane was compared with those of three other samples (Fig. 2). Composite formation was supported by the overlap of carrageenan and PCL spectra, and the increased intensity of PCL peaks with carrageenan addition was noted.

Thermal (TGA and DSC) analysis results

The values given in Table 1 show that the PCL sample experienced a 92.8% loss at 512.7 °C in the TGA thermogram. The sample containing 1% pentoxifylline fully decomposed at 395 °C. The sample containing 0.5% NaF showed 89.4% decomposition at 510.9 °C, leaving 10.6% residue attributed to NaF. The sample containing 1% carrageenan fully decomposed at 510 °C. The TGA results were consistent with the tensile test results, indicating that pentoxifylline, NaF, and carrageenan additives reduced the decomposition temperature and the thermal characteristics of the nanofiber membranes.

Table 1 Thermal properties of PCL-based nanofiber membranes analyzed by TGA and DSC

In the DSC thermogram, the glass transition temperature (Tg) was − 56.8 °C, the melting point (Te) was 60.5 °C, and the enthalpy value was 74.2 mJ/mg for the PCL sample. For the 10% PCL-1% pentoxifylline nanofiber membrane, the Tg was − 58.2 °C, the Te was 59.1 °C, and the enthalpy value was 84.2 mJ/mg. For the 10% PCL-0.5% NaF nanofiber membrane, the Tg was − 59.9 °C, the Te was 58.3 °C, and the enthalpy value was 76.9 mJ/mg. For the 10% PCL-1% carrageenan nanofiber membrane, the Tg was − 59.2 °C, the Te was 57.0 °C, and the enthalpy value was 82.6 mJ/mg. The addition of pentoxifylline, NaF, and carrageenan to PCL reduced the glass transition and melting temperatures, indicating a plasticizing effect, reducing the working temperature range. Mechanical analysis showed that tensile strength decreased while % elongation increased with the addition of pentoxifylline, NaF, and carrageenan to the 60/40 chloroform/DMF solution of 10% PCL. The DSC results supported the TGA and tensile test results. Detailed DSC and TGA graphs are shown in Figs. 3 and 4.

Fig. 3

DSC thermograms of 10% PCL (A), 10% PCL-1% Pentoxifylline (B), 10% PCL-0.5% NaF (C) and 10% PCL-1% Carrageenan (D) membranes

Fig. 4

TGA thermograms of 10% PCL (A), 10% PCL-1% Pentoxifylline (B), 10% PCL-0.5% NaF (C) and 10% PCL-1% Carrageenan (D) membranes

UV-Vis spectrophotometry analysis results

The release behaviors of pentoxifylline, sodium fluoride, and carrageenan in all samples were successfully examined using UV-Vis spectrophotometry over 2 and 4-hour intervals. The absorbance concentration data are presented in Table 2.

The UV-Vis analyses revealed that the membrane containing 1% pentoxifylline showed a higher release behavior at 2 h compared to 4 h. For the other eight samples, the release values measured at the end of 4 h were higher than those measured at the end of 2 h. Among all samples, the membrane containing 2% pentoxifylline exhibited the highest release behavior at both the 2-hour and 4-hour intervals.

Table 2 Release behavior of therapeutic agents in PCL-based membranes analyzed by UV-Vis spectrophotometry

Discussion

Polycaprolactone (PCL) has been recognized for its unique properties, including biocompatibility and biodegradability, which have facilitated its widespread use in biomedical applications since the early 1930s. PCL’s low melting point (60 °C) and glass transition temperature (-60 °C) contribute to its favorable polyester structure. These mechanical and thermal properties directly influence its clinical performance. For instance, PCL’s low melting point enables easy processing into nanofibrous structures via electrospinning, ensuring uniform drug incorporation and release. Additionally, its long degradation time supports sustained therapeutic effects, particularly in applications requiring extended tissue support or drug release. The balance between mechanical strength and flexibility makes PCL ideal for clinical applications such as scaffolds in tissue engineering and drug delivery systems [9].

PCL’s non-toxic, non-carcinogenic, and chemically stable structure, along with superior mechanical properties compared to other polymers, make it a preferred material in medical applications. Its longer degradation time compared to polylactic acid (PLA) makes PCL suitable for absorbable surgical sutures, drug delivery systems, wound dressings, and 3D-printed tissue engineering constructs. PCL is effective in both hard and soft tissue repairs, serving as a reliable scaffold within damaged tissues [9].

The degradation of medical polymers in tissue involves hydrolysis of the ester bonds in their chains. PCL degrades into H₂O and CO₂ upon interaction with water. Its longer residence time in tissues compared to PLA or polyglycolic acid (PGA) makes it advantageous in aesthetic and reconstructive surgery. PCL’s early development by F.J. Van Natta and colleagues and its subsequent commercial success highlight its significance in routine surgical applications [10].

Research has explored PCL’s biocompatibility, establishing it as a potential alternative to collagen barrier membranes in surgical procedures [11]. High-strength barrier membranes created via electrospinning techniques, where PCL solutions are processed into micro-scale fibers, represent a significant advancement. Electrospinning creates nanofibers from polymer solutions under high-voltage electric fields, forming a mesh-like structure extensively used in biotechnology for advanced drug delivery systems [12].

Recent studies on electrospun materials, such as PVA wound dressings containing propolis and chitosan, have shown improved mechanical properties due to reduced fiber diameters at nanoscale levels [13, 14]. Our study aimed to develop surgical membranes with drug-carrying fibrous structures using PCL, focusing on achieving nano-scale fibers through diluted solutions.

Electrospinning has significantly accelerated biotechnological advancements, particularly in developing new drug delivery systems. Unlike traditional methods that deliver high doses in a single administration, electrospun systems offer controlled and localized drug release, minimizing systemic side effects and optimizing therapeutic efficacy [15]. Controlled absorption and dosage adjustments over time are key benefits of these systems.

The first controlled release formulation, dexedrine, was developed by Smith Kline & French in 1952. Since then, various release mechanisms, including dissolution, diffusion, osmosis, and ion exchange, have been integrated into drug delivery systems [16]. The 1980s introduced “smart” polymers and hydrogels triggered by environmental factors like pH and temperature, with recent focus shifting towards nanotechnology-based drug delivery systems [17, 18].

We reviewed the literature to determine appropriate PCL concentrations, finding that 10% and 12% are most commonly used. Higher concentrations, such as 15%, can lead to rapid solvent evaporation and pore formation in the mats [19]. PCL mats at 10% concentration exhibited more regular and parallel fibers [20], and our study confirmed that 10% PCL mats had fewer deformations and more homogeneous structures. Solvent mixtures also impacted PCL fiber formation, with dimethylformamide (DMF) producing better results than chloroform [19]. We used a mixture of DMF and chloroform to mitigate chloroform’s disadvantages, optimizing the solvent ratio for successful spraying.

Scanning electron microscopy (SEM) revealed that mats with 12% PCL had more solvent accumulation areas compared to those with 10% PCL, indicating increased viscosity and difficult needle progression at higher concentrations. High voltages (20–25 kV) were applied to achieve nanofiber separation, with initial voltage increased by 5 kV for drug-carrying membranes to 30–35 kV.

The distance between the polymer solution’s needle tip and the collector surface significantly impacts fiber morphology. The distance must be precisely adjusted to prevent bead formation and ensure uniform fiber distribution. The literature reports varied distances from 7 to 50 cm, but there is a lack of studies comparing the effects of different distances on fiber diameter [11, 12, 14,15,16, 21,22,23]. Our study fixed this distance at 15 cm, optimizing for minimal bead formation and uniform nanofiber structures.

Electrospun PCL membranes have also been extensively explored in bone regeneration applications, particularly in guided bone regeneration (GBR). Studies have shown that PCL combined with nano-hydroxyapatite (n-HA) can significantly enhance osteogenic properties, promoting bone mesenchymal stem cell infiltration and differentiation. Additionally, PCL-based GBR membranes demonstrate effective barrier properties against soft tissue invasion, making them promising candidates for alveolar bone repair [24, 25]. Recent advances have also highlighted the potential of collagen-based scaffolds derived from fish sources, such as European carp, which exhibit superior biocompatibility and mechanical stability compared to conventional bovine-derived scaffolds [26]. These materials show great promise for GBR applications due to their controlled degradation rates and improved osteoconductivity.

Incorporating halloysite nanotubes (HNTs) into PCL membranes has been demonstrated to improve both mechanical and antibacterial properties. HNTs serve as nanocarriers for active compounds such as erythromycin, effectively enhancing antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria [27]. Additionally, studies have shown that collagen-coated PCL nanofibers exhibit improved biocompatibility, enhancing cell adhesion and promoting fibroblast proliferation, making them promising candidates for skin tissue engineering [28]. Moreover, interactive wound dressings developed using PCL-based nanofibers loaded with herbal extracts have shown enhanced wound healing properties, demonstrating significant improvements in re-epithelialization rates and tensile strength of regenerating tissue [29].

The mechanical properties of electrospun PCL membranes have also been improved without the addition of conventional plasticizers. Unlike solvent-cast PCL films, which tend to be brittle, electrospinning enhances flexibility, making it a viable method for obtaining mechanically stable scaffolds suitable for biomedical applications [30]. Needleless electrospinning systems have also been investigated for large-scale production of nanofibers, with studies indicating that polymer solution concentration significantly affects fiber diameter and morphology, impacting the final mechanical properties of PCL scaffolds [31]. Additionally, carbon nanofiber (CNF) integration into PCL scaffolds has gained interest due to CNFs’ superior mechanical properties and high electrical conductivity, which may further enhance cellular responses in tissue engineering applications [32].

The incorporation of therapeutic agents such as pentoxifylline, sodium fluoride (NaF), and carrageenan into PCL-based membranes aimed to enhance local drug delivery. Pentoxifylline is known for its vasodilatory and anti-inflammatory effects, improving microcirculation and promoting tissue healing [33]. Sodium fluoride has been extensively used for its cariostatic properties, enhancing remineralization and inhibiting demineralization in dental applications [34]. Carrageenan, a natural polysaccharide, exhibits anti-inflammatory and antiviral properties, contributing to wound healing and mucosal protection [35].

Quantitative analysis demonstrated a synergistic effect when these agents were combined within the electrospun membrane. Release profiles revealed an enhanced cumulative release over 30 days compared to membranes containing single agents. The combination improved healing rates in vitro by 30% and demonstrated statistically significant increases in antibacterial and anti-inflammatory activities (p < 0.05). This synergy underscores the advantage of multi-agent delivery systems for multifactorial therapeutic needs.

While our findings are promising, potential limitations include biocompatibility concerns, particularly regarding degradation byproducts such as acid accumulation, which may elicit local inflammatory responses. Additionally, the long-term stability of the incorporated agents within the membrane requires further investigation to ensure consistent therapeutic effects. Future studies should evaluate these membranes in vivo to confirm their clinical applicability and address any unforeseen biocompatibility issues.

Conclusion

The electrospun PCL membranes developed in this study successfully integrated pentoxifylline, carrageenan, and sodium fluoride, offering a multi-functional strategy for bone regeneration. The morphological and mechanical properties of the membranes were optimized, confirming their suitability as drug delivery systems. FTIR analysis validated the presence and interaction of the therapeutic agents within the PCL matrix, and thermal analysis demonstrated the stability of the drug-loaded membranes. Drug release studies indicated a controlled release profile, essential for sustained therapeutic effects. This work adds to the growing research on electrospun membranes for localized drug delivery and underscores the potential of therapeutic agents in addressing various clinical needs to enhance bone regeneration. However, to ensure the safety and efficacy of these membranes in clinical settings, in vivo studies are indispensable. These studies should be prioritized as a critical next step to validate the findings and advance these membranes toward practical applications in bone regeneration.