Antibacterial, self-healing, and pH-responsive PVA/ZIF-8@tannic acid nanocomposite hydrogel for sustained delivery of garlic extract

Abstract

Hydrogels are increasingly recognized in biological research due to their unique characteristics and broad potential applications. In this study, a pH-responsive hydrogel-based nanocomposite was designed with antibacterial activity and self-healing ability, highlighting its promising applications in biomedical engineering and materials science. The hydrogel-based nanocomposite consists of a polyvinyl alcohol (PVA) hydrogel crosslinked with borax (PB), zinc-based zeolitic imidazolate framework-8 nanoparticles modified with tannic acid (ZIF-8@TA), and garlic extract. The pH-responsiveness of the hydrogel arises from ZIF-8@TA and borax, which undergoes controlled degradation in acidic and basic conditions, enabling the targeted release of zinc ions beneficial for infected wounds. Its physicochemical and mechanical properties, self-healing abilities, and rheological behavior have been thoroughly investigated. The antimicrobial efficacy, antioxidant activity, biocompatibility, and release of zinc and sulfur ions were also evaluated. Mechanical analysis demonstrates tensile strengths ranging from 109 to 353 kPa, highlighting the material's versatility and suitability for applications such as wound dressings. Additionally, the hydrogels exhibited healing efficiencies ranging from 65.45 to 85.27% across samples with varying ZIF-8@TA concentrations (5-15 wt%). Antibacterial studies of hydrogels (0.5 g/mL) demonstrated 100% bacterial inhibition against Escherichia coli and Staphylococcus aureus strains, while significant antioxidant activity and sustained release of zinc and sulfur ions were observed over a 15-day period. These findings make the ZIF-8@TA-modified PVA hydrogel a promising candidate for advanced biomedical applications, addressing challenges in infection management, tissue regeneration, and adaptability to diverse wound environments.

Keywords: Antibacterial; Garlic extract; Hydrogel; PVA; Self-healing; ZIF-8.

Fig. 1

(a) XRD patterns for ZIF-8 and ZIF-8@TA; (b) FTIR spectra for ZIF-8 and ZIF-8@TA; (c) Mean size of ZIF-8 and ZIF-8@TA nanoparticles as determined from DLS analysis; (d) Zeta potential values for ZIF-8 and ZIF-8@TA.

Fig. 2

(a) FESEM images of ZIF-8 nanoparticles; (b) FESEM images of ZIF-8@TA nanoparticles; (c) Map and EDX of ZIF-8; (d) Map and EDX of ZIF-8@TA.

Fig. 3

(a) XRD for PVA, PB, PBTZ, and PBTZ/Garlic extraction; (b) FTIR spectra for PVA, PB, PBTZ, garlic extraction, and PBTZ/Garlic extraction; (c) Raman spectra for PBTZ10/Garlic.

Fig. 4

(a) Maximum swelling ratio and (b) timed-dependent swelling behavior of PB and ZIF-inclusive PB hydrogels in acidic, basic, and neutral pH environments.

Fig. 5

Tensile stress–strain curves of the original (a) and healed (b) samples; Toughness (c) and Young’s modulus (d) of the specimens before and after the healing; (e) Healing efficiency of the hydrogels calculated from the tensile strength; (f) Compression stress–strain curves of the specimens.

Fig. 6

(a) Depiction of the self-healing abilities of the samples and the formation of chemical and physical bonds in each stage of healing; (b) Cyclic strain sweep test of the specimens under strains of 1% to 400% and an angular frequency of 1 rad/s. Solid symbols denote Gʹ and hollow symbols represent Gʹʹ; (c) Optical microscope images displaying both intact and repaired hydrogels.

Fig. 7

(a) Variations in Gʹ and Gʹʹ under different frequencies; (b) Modifications in Gʹ and Gʹʹ of the specimens under strain at a consistent frequency. Solid symbols denote Gʹ and hollow symbols represent Gʹʹ.

Fig. 8

FESEM images of the hydrogel morphologies: (a,d) PB hydrogel, (b,e) PBTZ10 hydrogel, and (c,f) PBTZ10/Garlic sample.

Fig. 9

Map and EDX of PBTZ10/Garlic hydrogel.

Fig. 10

(a–f) The antibacterial effect of PBTZ10 and PBTZ10/Garlic hydrogels against S. aureus and E. coli; (g) Statistical evaluation of antibacterial efficiency; (h,i) Release profile of zinc and sulfur ions at various pH levels over 360 h; (j) Antioxidant activity of PBTZ10 and PBTZ10/Garlic, PBZ, and PB/Garlic in different concentrations.

Fig. 11

The cellular viability of the specimens in extractions with concentrations of 0.08 and 1 mg/ml that are prepared after 1, 3, and 5 days. The results of PBTZ10 and PBTZ10/Garlic samples after (a,c) 24 h and (b,d) 72 h of incubation.