Effect of tannic acid content on the properties and antibacterial activity of Shapeable polyvinyl alcohol/sodium alginate/tannic acid/borax (PBST) composite hydrogels

Tannic acid (TA), a natural polyphenol with multiple phenolic hydroxyl groups, is a promising functional component in hydrogel systems. In this study, the role of TA concentration (2, 4, and 8 mg/mL) in polyvinyl alcohol/sodium alginate/tannic acid/borax (PBST) composite hydrogels prepared by a one-pot method was systematically investigated. The shapeability, compressive/rheological properties, swelling, degradation, biocompatibility, and antibacterial activity of the composites were evaluated. Increasing the TA content from 2 to 8 mg/mL raised the compressive modulus from 1.80 to 25.46 kPa, improved rheological performance, and reduced the swelling ratio at 96 h from 67.44% to 29.67% as well as the degradation rate at 21 days from 56.07% to 22.62%, although shapeability decreased at the highest TA level. The hydrogels exhibited favorable in vitro and in vivo biocompatibility. Antibacterial efficacy also increased with TA dosage: the antibacterial rates against Staphylococcus aureus / E. coli were 31.10%/30.01% for PBST0.2, 69.23%/56.75% for PBST0.4, and 79.07%/59.80% for PBST0.8, with the highest TA concentration showing the strongest overall antibacterial effect. The findings suggest that TA is an effective regulator of PBST hydrogel performance, enhancing mechanical and antibacterial properties and being associated with reduced swelling and degradation without obvious loss of biocompatibility. However, the underlying network-related mechanisms remain to be further verified by direct structural characterization in future studies.

Natural polyphenols represent a class of organic compounds widely found in plants that incorporate multiple phenolic hydroxyl groups in their molecular structure (Zagoskina et al., 2023). Recent studies have shown that natural polyphenols exhibit a range of biological activities, including anti-inflammatory, antioxidant, antitumor, and cardiovascular protective effects (Ciupei et al., 2024; Razali et al., 2022; Fu et al., 2024). For instance, green tea and its extracts have demonstrated significant effects in reducing total cholesterol and low-density lipoprotein cholesterol (Zhao et al., 2022), while tea polyphenols exhibit proliferation inhibitory effects on various tumor cells (Dwivedi et al., 2025; Li et al., 2022). Tannic acid (TA), or gallotannin, is a water-soluble natural polyphenol found in plant tissues such as bark and fruit. The high phenolic hydroxyl group content facilitates TA crosslinking with various functional groups via hydrogen bonding, coordination, and covalent/non-covalent interactions, resulting in strong interfacial adhesion properties. Consequently, TA is a suitable component in functional polymer materials, particularly hydrogel systems (Liu Y. et al., 2025).

Hydrogels are hydrophilic polymer materials with a three-dimensional network structure and generally exhibit good biocompatibility, degradability, and structural adaptability, making them attractive for biomedical materials development (Segneanu et al., 2025). Natural polymers have also been widely used in hydrogel systems because of their biocompatibility and biodegradability; among them, alginate is a representative example frequently employed in biomedical hydrogel design. In tissue engineering and related biomedical applications, hydrogels can provide spatial support and a simulated microenvironment for tissue-defect sites (Halperin-Sternfeld et al., 2023). Their abundant hydrophilic groups and porous network structure also facilitate the loading, immobilization, and delivery of bioactive factors, stem cells, and biological fluids (Jiao et al., 2025). Accordingly, current hydrogel research has focused on regulating physicochemical and functional properties to improve material performance in drug delivery, wound healing, tissue regeneration, and other biomedical scenarios (Li et al., 2025; Liang et al., 2025; Kwon et al., 2019). Materials used in these biomedical application areas include natural polymer-based hydrogels, synthetic polymer-based hydrogels, and their composite systems, which are designed to balance biocompatibility, mechanical support, degradability, and functional performance. In this context, incorporating natural polyphenolic components with multiple activities and reactive characteristics into hydrogel systems is a useful strategy for constructing composite hydrogels that combine structural stability with biological functionality.

Among natural polyphenols, tannic acid (TA) has been widely investigated because of its multiple phenolic hydroxyl groups and its ability to participate in hydrogen bonding, coordination, and covalent/non-covalent interactions. In previous studies, TA incorporation into hydrogel systems has mainly been explored for tissue adhesion, mechanical reinforcement, antioxidant/antibacterial activity, self-healing behavior, injectability, and network stabilization. In PBST hydrogels, PVA and borax form the primary crosslinking network via dynamic borate ester bonds, whereas SA and TA contribute to a secondary network through hydrogen bonding. This network design gives PBST hydrogels shapeability and dynamic characteristics, making them potentially relevant as adaptable biomaterial candidates for irregular tissue-defect sites or other situations requiring conformal filling and temporary protection. However, previous studies have not systematically clarified how TA dosage affects the comprehensive performance of PBST hydrogels. Therefore, in the present study, PBST hydrogels were first prepared with different TA concentrations by a one-pot method. Their macroscopic molding and stretching characteristics were then examined, followed by measurements of compressive modulus and rheological behavior, analysis of swelling and degradation, evaluation of cytocompatibility with PDLSC, and assessment of antibacterial activity against Staphylococcus aureus and Escherichia coli. This stepwise design was intended to reveal the concentration-dependent role of TA in modulating the overall properties of the PBST hydrogel system.

Materials

Polyvinyl alcohol (PVA, 95%, Mw 89,000–98,000), sodium alginate (SA, AR grade, 90%), tannic acid (TA, AR grade, 98%, Mw 1701.2), and borax pentahydrate (99.5%, Mw 291.29) were purchased from Macklin (Shanghai, China).

The instruments used in this study included a universal mechanical testing machine (5965, Instron, Norwood, MA, USA), a rheometer (MCR 302e, Anton Paar, Graz, Austria), a centrifuge (5810R, Eppendorf, Hamburg, Germany), and a fluorescence microscope (IX73, Olympus, Tokyo, Japan).

Methods

Preparation of PBST hydrogels

A 5 mL 32 mg/mL TA solution and 3 mL 29.13 mg/mL borax solution were prepared. A sample (850 mg) of PVA was dissolved in deionized water under magnetic stirring at 90 °C in a water bath, with the subsequent addition of 300 mg SA, stirring at 300 rpm for 1 h. The TA solution was then added and stirred, followed by the borax solution to form a gel, yielding the PBST hydrogel product, which is denoted as PBST0.4. Applying the same procedure using 16 mg/mL and 64 mg/mL TA solutions produced PBST 0.2 and PBST 0.8 hydrogels, respectively. TA concentrations of 2, 4, and 8 mg/mL were selected based on preliminary formulation screening and with reference to (Zhao et al., 2021). These concentrations represented low, intermediate, and high TA levels under the present preparation conditions while maintaining stable gelation and enabling meaningful comparison of handling and functional performance. Concentrations below 2 mg/mL showed less obvious property differences, whereas concentrations above 8 mg/mL reduced shapeability.

Physicochemical and mechanical evaluation

The PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels were added to tensile molds, and stretched without fracture to determine the maximum tensile length of each group.

The PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels (diameter of 1 cm and height of 1 cm) were loaded into a universal mechanical testing machine and compressed at 1 mm/min until material fracture, recording the stress-strain curves. Hydrogels with a 0.2 cm diameter were subjected to rheological testing. Frequency sweeps were performed at a strain of 0.5% over a 0.1–100 rad/s angular frequency range.

Taking 500 μL samples of PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels, the initial weight (W0) was recorded. A 500 μL PBS solution was added to each group at 37 °C. The PBS solution was removed at times 0, 12, 24, 48, 72, and 96 h, and the sample weight (Ws) was recorded. The degree of swelling for each group is calculated from 100% × (Ws - W0)/W0. In addition, 500 μL Dulbecco’s Modified Eagle Medium (DMEM) solution was added to each group at 37 °C. At 0, 1, 3, 7, 14, and 21 days, the DMEM solution was removed, weighing the dry samples (Wd). The resultant extent of degradation for each group is calculated from 100% × (W0 - Wd)/W0.

In vitro biological and antibacterial evaluation

In a 24-well plate, PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels were co-cultured with periodontal ligament stem cells (PDLSC) at a mass ratio of 1:1 with a serum-containing culture medium. Live/Dead cell staining was performed at days 3, 5, and 7; the ratio of live to dead cells in each group was determined by fluorescence microscopy.

In a 96-well plate, PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels were co-cultured with PDLSC at a mass ratio of 1:1 with a serum-containing culture medium. At days 3, 5, and 7, the medium in each well was replaced with 110 μL CCK-8 working solution (medium:CCK-8 = 10:1), incubated at 37 °C for 4 h, and the absorbance of each well was measured at 450 nm.

The PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels were co-cultured with S. aureus (S. aureus) and E. coli (E. coli) at 37 °C for 3 h. The co-cultured bacterial suspension was diluted to 1 × 10 5 CFU/mL-1 × 10 6 CFU/mL and evenly spread on agar plates. The plates were incubated at 37 °C for 12 h, photographed and the colonies were counted.

A 100 μL sample of the co-cultured bacterial suspension from each group (see Section 2.2.7) was centrifuged at 10,000 × g for 5 min at room temperature. The supernatant was discarded, washed once with physiological saline, and the bacterial concentration was adjusted to 1 × 10 7 CFU/mL with physiological saline. A 1 μL sample of N,N-Dimethylaniline N-oxide/propidium iodide (DMAO/PI) working solution (100×) was added to each 100 μL bacterial suspension, incubating at 37 °C in the dark for 15 min, and analyzing the resultant images by fluorescence microscopy.

In vivo biocompatibility evaluation

The animal tests were approved by the Ethics and Welfare Committee of Xuzhou Medical University (Approval No. 202311T002), and strictly adhered to the stipulated requirements of experimental animal ethics and welfare. Rats were anesthetized by intraperitoneal injection of a mixture of Zoletil 50 (30 mg/kg) and Xylazine (10 mg/kg) (mixture volume 0.1–0.12 mL/100 g). Rats were euthanized using CO 2 inhalation. Eight-week-old female Sprague Dawley (SD) rats were selected for the experiments. The experimental groups included a control group, PBST 0.2 group, PBST 0.4 group, and PBST 0.8 group. Following intraperitoneal anesthesia, the rats were randomly assigned to the control, PBST0.2, PBST0.4, and PBST0.8 groups (n = 3per group) to reduce allocation bias. The in vivo study was designed as a preliminary biocompatibility evaluation, and the sample size was determined based on the actual experimental conditions in accordance with the 3R principles, using the minimum number of animals necessary to obtain initial histological safety data. For histological assessment, HE-stained sections were evaluated in a blinded manner. Symmetrical incisions were made on both sides of the midline of the SD rats’ back, 200 mg of each hydrogel material was added subcutaneously, and the incisions were tightly sutured. The rats in the control group received no treatment. This animal model was used for preliminary subcutaneous implantation biocompatibility assessment and was not designed as a scar-remodeling model.Therefore, gross scar images and healing ratio analysis were not included as study endpoints in the present in vivo experiment.

Visceral tissue specimens from each group of rats were obtained for HE staining to assess in vivo biocompatibility.

Statistical analysis

The SPSS 22.0 package was employed for statistical analysis. One-way analysis of variance (ANOVA) was utilized for comparisons involving three or more groups. Following ANOVA, Tukey’s HSD test was used in post-hoc pairwise comparisons. Paired t-tests were employed when comparing two groups. A P-value <0.05 was considered statistically significant.

Hydrogel plasticity

The PBST hydrogels can be shaped into different three-dimensional structures, such as circles and triangles, as illustrated in Figure 1A. These shapes maintain structural stability, demonstrating good plasticity. The morphology of PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels shaped into cubes can be compared in Figure 1B. The PBST 0.2 and PBST 0.4 hydrogels exhibit good shaping ability, forming relatively complete three-dimensional structures. In contrast, the PBST0.8 hydrogel exhibited less regular macroscopic shape retention after molding under the same conditions, suggesting reduced shapeability relative to PBST0.2 and PBST0.4.

Macroscopic stretching behavior

The tensile features of PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels formed using the same mold (Figure 1E) are shown in Figure 1C. All three groups maintained structural integrity without fracture when stretched to 20 cm. Further stretching to 40 cm resulted in the fracture of PBST 0.2 and PBST 0.8, whereas the PBST 0.4 hydrogel remained intact (Figure 1D), demonstrating superior tensile properties.

Compressive modulus

As shown in Figure 2A, the compressive modulus of the PBST hydrogels significantly increased with increasing TA concentration. The compressive moduli of PBST 0.2, PBST 0.4, and PBST 0.8 are 1.80 ± 0.58 kPa, 17.20 ± 3.75 kPa, and 25.46 ± 2.92 kPa, respectively, representing statistically significant differences between the groups. The results suggest that increasing the TA content reinforces the resistance of the PBST hydrogel to compressive deformation, which is likely related to stronger internal interactions within the matrix.

Rheological properties

In the 0.1–100 rad/s angular frequency (ω) range, the storage modulus (G′) of PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels was consistently higher than the loss modulus (G″), and no crossover point was observed (Figure 2B). This indicates that all three groups maintained a stable gel state within the tested frequency range. Furthermore, the G′values increased with increasing TA concentration, suggesting that TA enhances the elastic character of the hydrogel and contributes to improved structural integrity of the PBST system.

Swelling properties

As illustrated in Figure 2C, the three groups exhibited significant swelling within 72 h, accompanied by a rapid increase in volume. After 72 h, the rate of PBST 0.4 and PBST 0.8 hydrogel swelling decreased, but the degree of swelling continued to increase. The PBST 0.2 hydrogel maintained a higher swelling rate. At 96 h, the extent of PBST 0.2, PBST 0.4, and PBST 0.8 swelling is 67.44% ± 1.09%, 45.93% ± 2.56%, and 29.67% ± 0.59%, respectively, with statistically significant differences in the pairwise comparison of the groups. The results indicate that increasing the TA concentration decreases the swelling capacity of the hydrogels, supporting the interpretation that TA incorporation restricts water uptake and is associated with a more compact hydrogel organization.

Hydrogel degradation properties

The three hydrogels exhibited a slow degradation over the first 14 days (Figure 2D), maintaining a relatively unchanged morphology. Between days 14 and 21, the rate of degradation increased significantly, which is possibly related to a disruption of the hydrogel network structure and enhanced fluid exchange. At day 21, the extent of degradation of PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels reached 56.07% ± 6.31%, 34.86% ± 5.86%, and 22.62% ± 2.21%, respectively. Significant differences are observed for PBST 0.2 relative to the PBST 0.4 and PBST 0.8 groups, which are statistically equivalent. The results suggest that increasing TA content can lower the rate of hydrogel degradation, but any inhibition at high TA concentrations is limited.

Live/dead cell staining

The PDLSC were subjected to a live/dead staining assay after co-culture for 3, 5, and 7 days; the results are shown in Figure 3A. At each time point, the three hydrogel groups predominantly display green fluorescence with a secondary red fluorescence, indicating good cell viability. ImageJ semi-quantitative analysis data (Figure 3B) have revealed that, with the exception of the PBST0.4 group at day 5 where cell viability was significantly higher than the control group, there were no statistically significant differences between the other groups and the control at all time points. The results establish good in in vitro cytocompatibility with no obvious cytotoxicity where the TA concentration does not exceed 8 mg/mL.

CCK-8 cytotoxicity assay

As shown in Figure 3C, the optical density (OD) values for each hydrogel at days 3, 5, and seven showed no significant decrease when compared with the control group. Moreover, the OD increased with prolonged co-culture time, exhibiting a stabilized cell proliferation by day 7. The results confirm that the PBST hydrogels exhibit no significant cytotoxicity with respect to PDLSC, and cell proliferation is favorable. The data are consistent with the Live/Dead cell staining results.

Bacterial CFU assay

The CFU assay results following co-culturing PBST 0.2, PBST 0.4, and PBST 0.8 hydrogels with S. aureus and E. coli for 3 h are shown in Figures 4A,B. When compared with the control group, the PBST 0.2 hydrogel shows weak antibacterial activity for both bacteria, whereas PBST0.4 and PBST 0.8 hydrogels exhibit a marked reduction in the colony counts. This response indicates that a higher TA content enhances hydrogel antibacterial activity.

The antibacterial rates of each hydrogel group with respect to the two bacteria are presented in Figure 4C. In the case of PBST 0.2, the antibacterial rates are 31.10% ± 3.57% and 30.01% ± 4.24% for S. aureus and E. coli, respectively, significantly lower than the values recorded for PBST 0.4 (69.23% ± 8.86% and 56.75% ± 6.19%) and PBST 0.8 (79.07% ± 4.35% and 59.80% ± 2.49%). Although the overall antibacterial activity of the PBST 0.8 group is higher than that of the PBST 0.4 group, the differences are not statistically significant.

Live/dead bacterial staining

Live/Dead bacterial staining results following co-culturing for 3 h are shown in Figures 4A,B. When compared with the control group, three PBST hydrogels exhibit varying degrees of diminished green fluorescence and enhanced red fluorescence, indicating a decrease in live bacteria and an increase in dead bacteria. The PBST 0.8 hydrogel shows the most intense red fluorescence, demonstrating a superior bactericidal effect. The extent of bacterial mortality obtained from semi-quantitative analysis is presented in Figure 4D. The PBST 0.8 group exhibits the highest mortality for both bacteria, exceeding PBST 0.2 and PBST 0.4 groups which are statistically equivalent. This result is consistent with the CFU assay results, confirming that a higher TA concentration showed improved antibacterial activity overall.

HE staining

After 8 weeks, the rats in each group were euthanized, and heart, liver, spleen, lung, and kidney tissues were collected for HE staining; the results are shown in Figure 5. The major organ tissues in each group are intact, with no obvious tissue damage, necrotic foci, or abnormal cell proliferation. This response indicates that PBST hydrogels do not cause significant toxicity to the major organs, exhibiting good in vivo biocompatibility.

Hydrogels are viable materials for application in tissue engineering scaffolds due to their tunable physicochemical properties, good biocompatibility, and effective liquid absorption and retention (Zhang et al., 2020). Conventional physical hydrogels primarily form networks via non-covalent interactions, including hydrogen bonds, van der Waals forces, and ionic interactions that result in inferior mechanical properties and poor structural stability (Lu et al., 2018; Yang et al., 2025). Although chemical hydrogels exhibit improved crosslinking stability and good mechanical properties, the network structures are often irreversible, which hinders dynamic responsiveness and functional regulation (Gao et al., 2025). Consequently, the fabrication of composite crosslinked hydrogel systems that combine mechanical stability with dynamic reversibility represents a crucial direction in functional hydrogel research.

The proposed PBST hydrogels are constructed from PVA, SA, TA, and borax. The borate ester bonds formed between PVA and borax provide the mechanical support for the system, enabling a level of pH responsiveness that facilitates the controlled release of active components (Peng et al., 2024; Liang et al., 2022). Furthermore, TA and SA form a secondary crosslinking network through extensive hydrogen bonding that serves to increase the overall crosslinking density and structural stability of the system. In addition, this crosslinking can dissipate external energy through preferential hydrogen bonds scission, mitigating structural damage caused by localized stress concentration (Liu H. et al., 2025; Wang et al., 2022). The results of this study have established that, with increasing TA content, the elastic modulus, compressive modulus, and rheological properties of PBST hydrogels are significantly improved. This suggests that the hydrogen bonding network due to TA is a crucial factor in enhancing the material mechanical properties. Moreover, the dynamic reversibility of hydrogen bonds introduces self-healing material capabilities (Wang et al., 2023). The results suggest that TA serves as an important functional component, and is a key factor in regulating the network structure and hydrogel physicochemical properties.

Although increasing the TA content significantly enhances the mechanical properties of PBST hydrogels, this does not necessarily imply a concurrent optimization of overall material performance. A progressive increase in the crosslinking network density is accompanied by a decrease in the swelling capacity, degradation rate, and plasticity. The incorporation of TA serves to regulate network density. A higher crosslinking density improves structural stability and resistance to external forces but reduces the efficiency of internal fluid exchange and mass transfer, potentially affecting the targeted release of drugs or bioactive factors. Hydrogel degradation typically involves water absorption and swelling followed by a gradual network breakdown (Garcia-Garcia et al., 2024). A lower degree of swelling correlates with a lower rate of degradation, which may lead to an insufficient release of active components that compromises repair efficacy (Fratoni et al., 2021). Although a high TA concentration contributes to superior mechanical properties, sample plasticity is reduced, potentially limiting use in the repair of tissue defects with complex morphologies. Consequently, regulating the TA content is essential in order to achieve a balance of mechanical properties, degradation behavior, mass transfer capacity, and plasticity.

The TA component exhibits multiple biological activities, including anti-inflammatory, antibacterial, and antioxidant effects. Moreover, the molecular structure, rich in phenolic hydroxyl groups, facilitates functional modification (Sathishkumar et al., 2022). The results of this study have demonstrated that the hydrogels with varying TA concentrations exhibit antibacterial activity, where the medium and high concentration groups deliver superior antibacterial effects. This response establishes that TA incorporation effectively enhances the antibacterial activity of PBST hydrogels. The difference in the antibacterial effect of PBST 0.4 and PBST 0.8 is not significant, which may be related to a restricted release of TA from the densely crosslinked network under short-term co-culture conditions. The Live/Dead bacterial staining results are consistent with the CFU assay data, further demonstrating that the observed antibacterial activity is related to TA content. Improved antibacterial activity of tissue engineering scaffolds is an important feature where optimization requires a comprehensive consideration of the interplay between material degradation rate and tissue regeneration in order to balance infection control with tissue repair (Kang et al., 2024).

In addition to physicochemical properties and antibacterial activity, biocompatibility is fundamental for in vivo application of PBST hydrogels (Areevijit et al., 2021). The PDLSC co-culture experiments and in vivo implantation in SD rats have revealed that the PBST hydrogels with different TA concentrations do not exhibit obvious cytotoxicity or tissue irritation. The measurements indicate that the system possesses suitable in vitro and in vivo biocompatibility. This work partially addresses the current paucity of meaningful biological evaluations of the PBST system, providing experimental evidence for viable application in tissue repair and as antibacterial scaffold materials. Furthermore, considering the intended application of PBST hydrogels as defect-filling biomaterials, histological evaluation in an extraction socket defect model further demonstrated favorable local tissue compatibility and adaptation of the hydrogel within the defect environment.

These findings provide additional support for the potential application of PBST hydrogels in irregular tissue defect repair.

This study has certain limitations. First, the tensile properties of the PBST hydrogels were evaluated only by a preliminary macroscopic stretching test, and further standardized and quantitative mechanical assessments are still needed. Second, a PVA/SA/borax control hydrogel without TA was not included. Accordingly, the current findings are more appropriate to support a correlation between antibacterial performance and TA content, rather than a definitive attribution of the antibacterial effect solely to TA. Third, direct structural and mechanistic characterization remains insufficient. FTIR, XPS, and TA release analyses were not included in the current work, and although a preliminary SEM observation was performed on the representative PBST0.4 formulation and the corresponding images are provided in the Supplementary Material, systematic quantitative SEM analysis across all TA concentrations was not conducted; therefore, the proposed interactions within the PBST hydrogel network are supported only indirectly by the mechanical, rheological, swelling, and degradation results. In addition, direct evidence regarding the material microstructure and bacteria–material interfacial interactions is still lacking.

Furthermore, the current in vivo experiments mainly focused on biocompatibility evaluation, while more systematic investigations of the local inflammatory response, in vivo degradation behavior, and in vivo antibacterial efficacy are still warranted. Future studies will therefore include a TA-free control group, together with pH, osmotic, TA release, and additional structural characterization analyses, to further clarify the role of TA in network formation and antibacterial behavior, as well as to elucidate the underlying mechanisms more comprehensively.

The proposed PBST hydrogels exhibit suitable mechanical properties, biocompatibility, and antibacterial activity. The material properties are sensitive to the TA content. A judicious increase in the TA content serves to enhance the network stability and antibacterial effectiveness while reducing hydrogel swelling capacity, degradability, and plasticity. Optimizing the TA content is key to achieving a balanced regulation of PBST hydrogel performance. Within the tested concentration range, PBST0.4 was considered the more suitable base formulation because it provided a more balanced overall profile: compared with PBST0.2, it showed markedly improved mechanical stability and antibacterial performance, while compared with PBST0.8, it retained better moldability and more moderate swelling/degradation behavior. Thus, PBST0.4 achieved a more favorable compromise between structural stability, antibacterial function, and practical handling properties. The findings of this study can inform the design and application of antibacterial functional hydrogels where the proposed PBST hydrogels have significant potential as tissue engineering scaffold materials.