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. 2025 Aug 23;10(35):39441–39450. doi: 10.1021/acsomega.4c10343

Release Characteristic and Antioxidant Activity of Gac Seeds (Momordica cochinchinesis) from Collagen- and Chitosan-Based Hydrogel Composite

Thanyaluck Thanyacharoen †, Punyaporn Thongprasert †, Supanna Techasakul †, Sarute Ummartyotin ‡,§,∥,*, Piyachat Chuysinuan †,*
PMCID: PMC12423824  PMID: 40949266

Abstract

Chitosan- and collagen-based hydrogel composites were successfully prepared with 5–20 wt % gac loading, and this study explores their development and characterization, focusing on structural, thermal, swelling, antioxidant, and degradation properties for potential biomedical applications. Scanning electron microscopy (SEM) confirmed a well-integrated hydrogel network at lower gac concentrations, while higher loading led to particle agglomeration. All characteristic peaks investigated by Fourier transform infrared spectrometer are typically present in the similar features, suggesting that no change of structure properties is observed. The hydrogel is thermally stable within 200 °C. The glass transition temperature and melting temperature are to be 50 and 90–110 °C. With the presence of gac, no change of thermal and morphological properties is observed. Swelling behavior indicated that higher gac concentrations reduced water absorption, likely due to hydrophobic interactions. In addition, water solubility and water vapor transmission rates are reduced when gac is loaded. The optimal data are 54.05% and 888.19 g/m2/h, respectively. The hydrogel composite exhibits a burst release at the initial 300 min. The degradation is also very fast. Also, it illustrates the antioxidant activity as observed by the DPPH and ABTS assays. It is remarkably noted that antioxidant biomaterials have applications in wound dressing.

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1. Introduction

With the rapid growth of the global population, the demand for healthcare products that support food safety and medical technology has increased significantly. Among emerging technologies, hydrogel-based materials have attracted considerable attention due to their unique properties, such as high water retention, excellent swelling capacity, and the ability to support wound healing. Structurally, hydrogels are biphasic materials composed of a permeable solid matrix and interstitial fluid, making them suitable for diverse applications in agriculture, medicine, pharmaceuticals, and food technology. However, many conventional hydrogels are synthesized from polyolefin-based polymers, which pose environmental challenges due to poor biodegradability. To address these limitations, research has increasingly focused on biobased hydrogels. These materials not only offer biodegradability but also possess desirable functional properties. Among biobased polymers, chitosana linear polysaccharide derived from crustacean and insect exoskeletonsstands out due to its antibacterial activity, biocompatibility, and versatility in biomedical applications. However, pure chitosan exhibits brittleness and limited processability, prompting the development of chitosan-based composite hydrogels. −

Recent studies have explored various chitosan composites. For instance, Shi et al. developed chitosan-sodium alginate hydrogels cross-linked with epichlorohydrin, calcium chloride, and tannic acid, resulting in improved antibacterial properties. He et al. incorporated phenylboronic acid and SiO2 into chitosan hydrogels to enhance antioxidant activity and controlled release of bioactives. Ding et al. fabricated conductive polyacrylamide/carboxymethyl chitosan hydrogels for flexible strain sensors, showcasing excellent self-recoverability. , Despite these advancements, chitosan-based hydrogels often suffer from poor mechanical strength, limiting their long-term applicability. To enhance the durability and functionality, collagen has been introduced as a reinforcing component. As the primary structural protein in connective tissue, collagen provides excellent mechanical support and promotes cell adhesion and proliferation. , Lin et al. developed a collagen/carboxymethyl chitosan scaffold for cartilage regeneration, demonstrating improved mechanical and biological performance. Similarly, Zhang et al. reported a composite dressing from carboxymethyl chitosan, collagen peptide, and oxidized konjac, which effectively supported wound healing. While chitosan-collagen hydrogels provide a promising platform for biomedical use, the incorporation of bioactive compoundsparticularly antioxidantscan further enhance their functionality. Antioxidants play a vital role in both food and medical fields by preventing oxidative damage, enhancing product stability, and reducing disease risk. − Although synthetic antioxidants are effective, their production often involves harsh chemicals and complex procedures. , Therefore, natural antioxidants from plant-based sources have become increasingly attractive. In Thailand, a notable source of natural antioxidants is gac (Momordica cochinchinensis), a Southeast Asian fruit rich in lycopene and β-carotene. − Studies by Kubola et al. and Phan-Thi et al. highlighted its superior antioxidant capacity and potential for enhancing bioactivity in various applications.

In this study, we developed and characterized chitosan-collagen-based hydrogel composites incorporated with varying concentrations of gac extract (5–20 wt %). We investigated their structural, thermal, swelling, antioxidant, and degradation properties to evaluate their potential for biomedical applications, particularly wound dressings. Special focus was given to understanding how gac incorporation affects the hydrogel’s functional performance, including antioxidant activity and release behavior.

2. Experimental Section

2.1. Chemical Reagents and Materials

Low molecular weight chitosan (deacetylated chitin, poly­(d-glucosamine) is purchased from Sigma-Aldrich Co., Ltd. Collagen (molecular weight ≥ 80 g/moL) is purchased from Chemipan Corporation Co., Ltd. Gac seed extract is purchased from AP Operations Co., Ltd. Glacial acetic acid is purchased from RCI Labscan Asia Co., Ltd. Tetraethyl orthosilicate (TEOS) is purchased from Sigma-Aldrich Co., Ltd. 2,2′-Azino-bis­(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) are purchased from Sigma-Aldrich Co., Ltd. All chemical reagents are of analytical grade and used as received without any further purification.

2.2. Preparation of Chitosan- and Collagen-Based Hydrogel Composites

Chitosan/collagen-based hydrogel composites were prepared by solvent casting. Briefly, 2% (w/v) low molecular weight chitosan was dissolved in 0.5% (v/v) acetic acid solution under continuous stirring at 70 °C. Simultaneously, 1% (w/v) collagen was dissolved in distilled water at room temperature. The two solutions were then combined at a chitosan-to-collagen ratio of 7:3 (v/v) and stirred for 1 h at room temperature to achieve homogeneity. Subsequently, 1% (v/v) tetraethyl orthosilicate (TEOS) was added as a cross-linking agent, followed by an additional 1 h of stirring. The resulting mixture was cast onto Petri dishes and allowed to dry at room temperature.

For the preparation of gac extract-loaded hydrogel composites, gac extract was incorporated into the chitosan/collagen solution at concentrations of 5%, 10%, 15%, and 20% (w/w, relative to the total polymer content) prior to the cross-linking step. The pH values of the gac solutions were measured prior to incorporation, yielding values of 5.213 ± 0.012 for 5% gac, 5.007 ± 0.008 for 10% gac, 4.926 ± 0.015 for 15% gac, and 4.895 ± 0.009 for 20% gac, indicating a slight acidification with increasing gac concentration. Following incorporation and cross-linking, the mixtures were cast and dried as previously described. All prepared films were stored in a desiccator to minimize the moisture absorption.

2.3. Scanning Electron Microscope (SEM)

Surface morphology of the sample is investigated using a scanning electron microscope (JEOL JSM-6400). The sample is coated with a thin layer of gold by using a JEOL JFC-1100E sputtering device in order to enhance the electrical conductivity. A magnification of 1000× is used.

2.4. Fourier Transform Infrared Spectrometer (FTIR)

The chemical structure and functional group of the samples are determined by a Fourier transform infrared spectrometer (SPECTRUM ONE, PerkinElmer, USA). The samples are scanned from 650 to 4000 cm–1 at room temperature in attenuated total reflectance mode. The resolution of 4 cm–1 and an averaging of 32 scans are employed.

2.5. Thermogravimetric Analyzer (TGA)

The thermal decomposition behavior of the samples is measured by using TGA (NETZSCH TG 209 F3 Tarsus). 10 mg sample is heated from room temperature to 600 °C under nitrogen gas at a flow rate of 10 mL/min and a heating rate of 10 °C/min.

2.6. Differential Scanning Calorimeter (DSC)

The thermal properties of the sample are evaluated by using a differential scanning calorimeter (NETZSCH DSC 204 F1 Phoenix, Germany). The samples are heated from room temperature to 250 °C under a nitrogen atmosphere. The heating rate and flow rate are set at 10 °C/min and 10 mL/min, respectively.

2.7. Swelling Test

The chitosan- and collagen-based hydrogel composite is investigated for its swelling behavior by using the gravimetric technique. The dry sample is measured (W dry) and immersed in phosphate-buffered saline (PBS) buffer for 24 h. After an appropriate time interval, the sample is removed to a buffer and measured (W wet). The swelling behavior of the sample is determined as follows (eq )­

Swelling ratio (%)=(Wwet‐Wdry)/Wdry×100 1

where W wet is the weight of the swollen composite hydrogel at submersion time, and W dry is the initial weight of the dry composite hydrogel.

2.8. Water Solubility and Water Vapor Transmission Rate

The chitosan- and collagen-based hydrogel composite is weighed (W 0) and immersed in 10 mL of distilled water for 1 h. Then, the sample is removed, dried at 80 °C and measured for dry weight (W d). The water solubility of the sample is evaluated by eq

Water solubility(%)=[(Wd−W0)/W0]×100 2

The sample is investigated by WVTR in accordance with ASTM E96-90(1990). The sample is weighed (W i) and placed on the mouth of a bottle containing 10 mL of distilled water. After that, the sample is incubated at 35 °C for 24 h and is weighed (W t). The WVTR of the sample is calculated as eq

WVTR=[(Wi−Wt)/(A×24)]×106g/m2h 3

Where A is the area of a bottle mouth (mm)2.

2.9. Degradation Test

The chitosan- and collagen-based hydrogel composite is immersed in PBS buffer for 28 days. At each time point, the sample is withdrawn and dried at 60 °C. In addition, the sample is investigated as eq

Degradation(%)=WtW0×100 4

where W 0 and W t are the weights of the sample before and after degradation, respectively.

2.10. Release Characteristic

The chitosan- and collagen-based hydrogel composite is determined by its release characteristics by immersion methods. The sample is immersed in a media solution (Methanol: Tween 80: PBS) at a ratio of 3:0.5:96.5 for 24 h. At each time point, 0.5 mL of the media solution is withdrawn and an equal amount of fresh media solution is refilled to maintain a constant volume. The cumulative release of gac extract in the media solution is calculated on the basis of the calibration measurements, which are performed in triplicate.

2.11. Antioxidant Activity

The chitosan- and collagen-based hydrogel composites are determined as antioxidant activity by the DPPH radical scavenging activity and ABTS radical scavenging assay. The DPPH radical scavenging activity is determined using the method developed by Chuysinuan et al. Briefly, the sample is immersed in 10 mL of methanol for 24 h at room temperature. Then, 0.1 mL of an aliquot sample is mixed with 0.3 mL of DPPH solution (0.3 mM). Then, the sample is incubated in the dark for 30 min at room temperature. The absorbance of the sample is investigated at 517 nm. On the other hand, the ABTS radical scavenging activity is investigated using the method developed by Thanyacharoen et al. The ABTS solution is prepared by mixing 7.4 mM ABTS+ and 2.6 mM potassium persulfate. After that, 0.1 mL of an aliquot sample is mixed with 0.3 mL of ABTS solution. Then, it is incubated in the dark for 30 min at room temperature. The absorbance of the sample is investigated at 734 nm. The percentage of scavenging activity of both assays is calculated using eq

Scavenging activity(%)=[(Ablank−Asample)Ablank]×100 5

where A blank is the absorbance of the radical without the sample, and A sample is the absorbance of the radical in the presence of the sample.

3. Results and Discussion

3.1. Surface Morphology of Gac-Loaded Chitosan/Collagen-Based Hydrogel Composites

The morphological characteristics of gac-loaded chitosan/collagen-based hydrogel composites were analyzed by using SEM. Figure presents the microstructural features of the composite, showing a generally smooth hydrogel surface. The films exhibited thicknesses of 2.75 ± 0.05 mm for CS/Coll, 2.86 ± 0.08 mm for 5% Gac/CS/Coll, 2.75 ± 0.12 mm for 10% Gac/CS/Coll, 2.92 ± 0.07 mm for 15% Gac/CS/Coll, and 2.74 ± 0.06 mm for 20% Gac/CS/Coll, indicating good consistency across the samples and sufficient structural integrity for SEM imaging. At lower gac concentrations, the particles appear well-integrated within the hydrogel matrix. However, as the gac content increases, distinct clusters of particles become visible on the surface, indicating a potential agglomeration. This phenomenon is likely due to the limited dispersion of gac at higher concentrations, leading to particle aggregation. Similar morphological behaviors have been reported in previous studies, Zhang et al. observed that the SEM images of the collagen/chitosan complexes formed by the interaction of the two materials had a regular spherical shape and uniform particle size. This suggests that the incorporation of additives can influence the microstructural properties of the hydrogel matrix. These observations suggest that while the hydrogel network can effectively encapsulate gac, excessive loading may impact uniformity and structural integrity. Further optimization of the gac concentration and dispersion techniques could enhance the homogeneity and mechanical stability, improving the overall performance of the composite material.

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Morphological properties of gac-loaded into chitosan- and collagen-based hydrogel composites.

3.2. FTIR of Gac-Loaded Chitosan/Collagen-Based Hydrogel Composites

To study the functional groups of gac-loaded into chitosan- and collagen-based hydrogel composites, a Fourier transform infrared (FTIR) spectrometer was used to illustrate their characteristics. Figure reports the functional group determination of gac loaded into chitosan- and collagen-based hydrogel composites. The pristine gac and hydrogel are provided for comparison. All characteristic peaks are presented in the similar features. It is observed that the characteristic peaks at wavenumbers of 3270 and 2920 cm–1 are existed. These peaks are typically referred to as the O–H stretching and C–H stretching, respectively. Then, the peaks at the wavenumbers of 1640 and 1068 cm–1 are presented. These peaks correspond to CO stretching and C–O stretching, respectively. After that, the peaks at the wavenumbers of 1545 and 1404 cm–1 are observed. These peaks are attributed to N–H stretching. It can be remarkably noted that all of the peaks are presented as a functional group of both chitosan and collagen. With the presence of the O–H stretching and N–H stretching, the hydrogen bond linkages can be formed throughout the hydrogel network. It is facile to adhere with water molecule. , Moreover, with the presence of gac, no significant change of characteristic peaks is observed due to its lesser amount. Gac is incorporated into the hydrogel network. The investigation of FTIR is only a surface analysis. These findings are consistent with previous studies of chitosan- and collagen-based hydrogels, which also reported similar functional group peaks. For instance, FTIR spectra of chitosan- and collagen-based hydrogel composites have been documented, highlighting the presence of these functional groups. Additionally, the incorporation of gac into the hydrogel network did not significantly alter these characteristic peaks, suggesting that gac was incorporated into the hydrogel network without disrupting the structural integrity or hydrogen bonding interactions within the composite. This observation aligns with findings from other studies, where the incorporation of additional components into chitosan- and collagen-based hydrogels did not significantly alter the characteristic peaks of the individual components.

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FTIR spectra of gac-loaded into chitosan- and collagen-based hydrogel composites.

3.3. Thermal Stability of Gac-Loaded Chitosan/Collagen-Based Hydrogel Composites

The thermal decomposition behavior of gac-loaded chitosan- and collagen-based hydrogel composites, as investigated through TGA (Figure ), demonstrates a typical three-stage degradation pattern. The first stage, with a 15 wt % loss from room temperature to 200 °C, is attributed to the evaporation of water, aligning with the well-documented property of hydrogels to retain significant water content within their network. , The second stage, between 200 and 400 °C, represents the pyrolysis of organic components, where the hydrogel undergoes thermal degradation, releasing volatile gases such as CO2 and NOx, as similarly observed by Babgohari et al. The third stage, from 400–600 °C, shows a relatively minor weight loss of 10 wt %, marking the termination of organic pyrolysis and the stabilization of residual char. Importantly, the addition of gac to the hydrogel did not result in significant changes in the thermal decomposition behavior, indicating that gac integration does not substantially alter the thermal stability of the composite. This suggests that the thermal degradation mechanisms remain largely dominated by the hydrogel matrix itself, which is similar to other biobased composites that retain their thermal properties despite the incorporation of small amounts of bioactive substances or fillers. ,

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Thermal decomposition behavior of gac-loaded into chitosan- and collagen-based hydrogel composites.

3.4. Thermal Properties of Gac-Loaded Chitosan/Collagen-Based Hydrogel Composites

The DSC analysis of gac-loaded chitosan- and the collagen-based hydrogel composite, as shown in Figure , reveals that the presence of gac does not significantly alter the thermal transitions of the hydrogel. The glass transition temperature (Tg) is found to be approximately 50 °C, and the melting temperature range is observed between 90 and 110 °C, with no notable shift in these values upon the addition of gac. This suggests that the incorporation of a small amount of gac does not substantially influence the molecular dynamics of the hydrogel, specifically the transition between rigidity and flexibility or the enthalpy associated with melting. These findings are consistent with prior research indicating that small filler concentrations do not significantly alter the thermal properties of hydrogel systems, as the predominant thermal behavior is governed by the polymer network itself. , The lack of significant changes in the DSC curve further supports the conclusion that gac integration into the hydrogel network does not disrupt the overall thermal stability or molecular mobility of the composite, reinforcing its potential for various applications in which maintaining the thermal characteristics of the hydrogel is important.

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DSC analysis of gac-loaded into chitosan- and collagen-based hydrogel composites.

3.5. Swelling Ability of Gac-Loaded Chitosan/Collagen-Based Hydrogel Composites

The swelling behavior of gac-loaded chitosan-collagen (CS/Coll) hydrogel composites in a PBS solution was investigated to assess their potential for controlled release applications. Figure illustrates the swelling profiles of hydrogel samples with varying gac concentrations (0%, 5%, 10%, 15%, and 20%) over 24 h. The results indicate a rapid increase in swelling within the first 1–3 h, followed by a gradual increase and stabilization from 3 to 24 h, reaching a plateau. This pattern suggests an initial rapid water uptake due to hydrophilic groups in chitosan and collagen, followed by equilibrium swelling as the hydrogel matrix becomes saturated. Notably, the presence of gac significantly influences the swelling behavior. The pure CS/Coll hydrogel (without gac) exhibits the highest swelling percentage, while higher gac concentrations (10%, 15%, and 20%) lead to reduced swelling capacity. This decrease is likely due to the interference of gac with the chitosan-collagen polymer network, restricting water penetration and absorption. The high aromatic content in gac may disrupt hydrogen bonding within the hydrogel matrix, reducing the overall hydrophilicity of the composite. Similar reductions in swelling have been reported in hydrogels incorporating bioactive plant extracts, where polyphenolic compounds alter the polymeric interactions and water retention properties. ,

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Swelling behavior of gac-loaded chitosan- and collagen-based hydrogel composites.

3.6. Water Solubility and Water Vapor Transmission Rate

Water solubility and water vapor transmission rate (WVTR) are critical factors in evaluating the moisture-handling properties of the hydrogel composites. Table presents the water solubility and WVTR of chitosan-collagen (CS/Coll) hydrogels with varying gac concentrations. The data indicate that both parameters decrease significantly as gac content increases, consistent with the swelling behavior observed in Figure . The water solubility of the CS/Coll hydrogel (54.05%) is substantially reduced to 29.79% for the 20% Gac/CS/Coll hydrogel. This decrease suggests that gac incorporation limits water penetration and dissolution, possibly due to hydrophobic interactions and steric hindrance caused by the high aromatic content of gac. Similarly, the WVTR decreases from 888.19 g/m2/h (CS/Coll) to 511.40 g/m2/h (20% Gac/CS/Coll), indicating a lower rate of water diffusion through the hydrogel network. The reduced WVTR suggests that gac-loaded hydrogels may enhance moisture retention, which could be advantageous for applications requiring prolonged hydration, such as wound healing dressings and biomedical coatings. These findings align with previous research on hydrogel systems incorporating bioactive plant-derived compounds, where phenolic-rich components influence water transport properties by modifying the polymer matrix. , The ability to control water solubility and WVTR through gac concentration demonstrates the potential of these hydrogels for biomedical applications requiring tailored hydration properties.

1. Water Solubility and Water Vapor Transmission Rate of Gac-Loaded into Chitosan- and Collagen-Based Hydrogel Composites.

Sample Water solubility (%) Water vapor transmission rate (g/m2/h)
CS/Coll 54.05 ± 11.81 888.19 ± 217.48
5%Gac/CS/Coll 44.51 ± 7.34 615.15 ± 135.13
10%Gac/CS/Coll 38.72 ± 4.50 595.22 ± 116.22
15%Gac/CS/Coll 32.37 ± 1.29 536.11 ± 33.20
20%Gac/CS/Coll 29.79 ± 0.54 511.40 ± 122.74
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3.7. Release Characteristic

To investigate the controlled release potential of gac-loaded chitosan-collagen hydrogel composites, the cumulative release of gac extract over time was evaluated (Figure ). The release profile exhibits biphasic behavior, characterized by an initial burst release within the first 300 min, followed by a gradual and sustained release up to 1500 min. The burst release phase is attributed to gac molecules located near the hydrogel surface, which are rapidly diffused into the surrounding medium, a well-documented phenomenon in hydrogel-based drug delivery systems. This initial rapid release is a desirable feature in drug delivery applications, ensuring a high bioavailability of the active compound in the early stages of administration. Following this phase, the release stabilizes, indicating that the remaining gac is retained within the hydrogel matrix and is released in a controlled manner over time. Notably, the cumulative release percentage increases with a higher gac loading, demonstrating a positive correlation between gac concentration and release efficiency. The 20% Gac/CS/Coll hydrogel exhibits the highest release, suggesting that the increased gac content enhances diffusion through the polymeric network. This phenomenon is consistent with previous findings, where higher bioactive compound concentrations promote enhanced diffusion rates.

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Release characteristic of gac-loaded chitosan- and collagen-based hydrogel composites.

3.8. Degradation Behavior

The degradation characteristics of gac-loaded chitosan-collagen hydrogels were evaluated to determine their biodegradability and potential lifetime in biomedical applications. As shown in Figure , the degradation profile exhibits a steady increase over time, with approximately 30% weight loss within the first day, followed by a progressive increase, reaching nearly 60% degradation after 28 days. This gradual degradation suggests that the hydrogel matrix is undergoing hydrolytic breakdown, a key feature for controlled drug release and tissue engineering applications. The incorporation of gac does not significantly alter the degradation trend, indicating that gac does not interfere with the intrinsic degradability of the chitosan-collagen network. This behavior aligns with previous findings that chitosan-based hydrogels degrade primarily via enzymatic hydrolysis and dissolution of the polymeric network in aqueous environments. The degradation pattern is also consistent with the surface erosion mechanism, where water penetration leads to gradual polymer chain cleavage and mass loss. The observed degradation profile is comparable to other natural polymer-based hydrogels, such as gelatin, alginate, and hyaluronic acid hydrogels, which have been widely utilized for biomedical and drug delivery applications. , Importantly, the controlled degradation rate of gac-loaded hydrogels ensures a sustained release of gac bioactive compounds, making them suitable for wound dressing applications.

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Degradation of gac-loaded into chitosan- and collagen-based hydrogel composites.

3.9. Antioxidant Activity

The antioxidant activity of gac-loaded chitosan-collagen hydrogels was evaluated using DPPH and ABTS assays (Table ), revealing that 5 wt % gac exhibited the highest antioxidant efficiency (33.97% for DPPH and 85.53% for ABTS). However, as gac concentration increased to 10%, 15%, and 20%, antioxidant activity declined, likely due to steric hindrance, polymeric entrapment, and oxidative degradation, which limit the bioavailability of antioxidant compounds. , The higher ABTS values compared to DPPH suggest that hydrophilic interactions enhance radical scavenging in hydrogel matrices. These findings align with studies on gac fruit’s antioxidant-rich composition, primarily attributed to lycopene, β-carotene, and polyphenols, and the ability of hydrogels to stabilize and control antioxidant release. The strong antioxidant activity at 5 wt % gac suggests its potential for biomedical applications, such as wound healing and oxidative stress reduction, reinforcing studies on antioxidant biomaterials enhancing tissue regeneration. ,

2. Antioxidant Activity of Gac-Loaded into Chitosan- and Collagen-Based Hydrogel Composites.

  Antioxidant activity
Sample DPPH assay (%) ABTS assay (%)
CS/Coll 0 0
5% Gac/CS/Coll 33.97 ± 3.42 85.53 ± 0.42
10% Gac/CS/Coll 30.75 ± 4.88 69.85 ± 3.83
15% Gac/CS/Coll 21.73 ± 0.83 67.64 ± 1.27
20% Gac/CS/Coll 18.19 ± 6.78 67.89 ± 1.53
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4. Conclusion

This study successfully developed and characterized gac-loaded chitosan-collagen hydrogel composites, demonstrating their potential for biomedical applications. Morphological analysis via SEM revealed that gac was well-integrated into the hydrogel matrix at lower concentrations, while higher loadings led to agglomeration. FTIR analysis confirmed the preservation of functional groups, indicating that gac incorporation did not disrupt the hydrogel’s structural integrity. Thermal analyses (TGA and DSC) showed that gac loading did not significantly alter the hydrogel’s thermal stability, highlighting its compatibility with the polymer network. The swelling behavior and water solubility studies indicated that higher gac concentrations reduced hydrophilicity, which may be beneficial for controlled release applications. Release studies revealed a biphasic profile with an initial burst release followed by sustained release, supporting its potential as a bioactive delivery system. Degradation analysis confirmed the hydrogel’s gradual breakdown over 28 days, making it suitable for biomedical applications requiring controlled biodegradability. Antioxidant activity assays (DPPH and ABTS) demonstrated the highest efficiency at 5 wt % gac loading, with a decline at higher concentrations due to polymer entrapment and steric hindrance. These findings suggest that optimized gac-loaded chitosan-collagen hydrogels could serve as promising biomaterials for applications, such as wound dressing.

Supplementary Material

ao4c10343_si_001.pdf (91KB, pdf)

Acknowledgments

This work was supported by Thailand Science Research and Innovation (TSRI), the Chulabhorn Research Institute (Grant No. 49896/4759815), the Thailand Science Research and Innovation Fundamental Fund fiscal year 2025, and the Hub of Talent: Sustainable Materials for Circular Economy, National Research Council of Thailand (NRCT).

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.4c10343.

  • Table S1: TGA data of gac-loaded chitosan/collagen-based hydrogel compositesTable S2: DSC data of gac-loaded chitosan/collagen-based hydrogel composites (PDF)

The authors declare no competing financial interest.

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