pH-responsive agarose hydrogel for enhanced gastrointestinal ibuprofen delivery: A novel pressure-sensitive adhesive system

Abstract

Recent advances in pH-responsive drug delivery systems have demonstrated their promising potential for targeted therapeutic delivery. However, challenges remain in developing platforms that combine precise spatiotemporal control with robust mechanical properties. Herein, we present a novel plant-derived (agarose-polyacrylic acid hybrid) hydrogel pressure-sensitive adhesive (PSA) system that combines the biocompatibility of agarose with the pH-responsiveness of polyacrylic acid for controlled ibuprofen delivery.

Highlights

Novel pH-responsive agarose-polyacrylic acid hydrogel for controlled ibuprofen delivery.

High drug incorporation (78.1 ± 3.4 %) with minimal burst release (<15 %) in gastric conditions.

Targeted intestinal release (64.9 ± 1.7 %) with substantial drug amorphization (87.8 %).

Stable drug-polymer interactions validated by molecular dynamics (ΔG = −25.3 kJ/mol).

Reduced dosing frequency and improved patient compliance with NSAID therapy.

Unlike conventional physical encapsulation methods, our covalently tethered design achieved 78.1 ± 3.4 % drug incorporation efficiency with minimal burst release (<15 %), representing a 3.5-fold improvement over traditional alginate systems (p < 0.01). The hybrid matrix demonstrated pH-dependent swelling ratios ranging from 1.58 ± 0.09 (pH 1.2) to 3.29 ± 0.12 (pH 7.4) and programmable mechanical properties, with the storage modulus decreasing from 2000 ± 150 Pa to 1000 ± 90 Pa across pH 1.2–9.0 (F = 28.4, p < 0.001). The hierarchically porous architecture (11.33 ± 6.27 μm) enables Fickian diffusion-controlled release (Korsmeyer-Peppas n = 0.30–0.41), while molecular dynamics simulations confirm stable drug-polymer interactions (ΔG = −25.3 kJ/mol).

Thermal analysis revealed significant drug amorphization (87.8 % reduction in crystallinity), promoting enhanced solubility. In vitro studies demonstrated pH-triggered delivery, with 64.9 ± 1.7 % release at intestinal pH versus < 15 % at gastric pH, while maintaining PSA adhesive strength (>150 kPa). This scalable platform addresses the critical limitations of conventional NSAID delivery, including gastric toxicity (prevalent in 50–60 % of chronic users) and frequent dosing, by synergizing plant-derived biocompatibility with synthetic flexibility.

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Materials

Ibuprofen (≥98 % purity) was a gift sample from the National Pharmaceutica Industry, Rusayl, Muscat, Oman. Carbomer 974 P, average Mw ∼1000,000 Da, crosslinked polyacrylic acid polymer) was obtained from Lubrizol (Wickliffe, OH, USA). Agarose (C₁₂H₁₈O₉, low electroendosmosis (EEO), molecular biology grade, linear polysaccharide of D-galactose and 3,6-anhydro-L-galactopyranose, Mw 306.12 g/mol, viscosity 1 % solution at 37°C: 8–13 cP) was procured from Fisher Scientific (Hampton, NH, USA). N,N\’-methylenebisacrylamide (MBA, ≥99.5 %), ammonium persulfate (APS, ≥98 %), and N,N,N\’,N\’-tetramethylethylenediamine (TEMED, 99 %) were acquired from Sigma-Aldrich (St. Louis, MO, USA). 1,3-Propanediol (98 %), 4-dimethylaminopyridine (DMAP, ≥99 %), and N,N\’-dicyclohexylcarbodiimide (DCC, 99 %) were purchased from Acros Organics (Geel, Belgium). Anhydrous dichloromethane (≥99.8 %), ethyl acetate (HPLC grade, ≥99.8 %), and n-hexane (HPLC grade, ≥95 %) were obtained from Fisher Scientific. Hydrochloric acid (HCl, 37 %), sodium bicarbonate (NaHCO3, ≥99.7 %), sodium hydroxide (NaOH, ≥98 %), citric acid (≥99.5 %), acetic acid (glacial, ≥99.7 %), and boric acid (≥99.5 %) were procured from Sigma-Aldrich. Phosphate-buffered saline (PBS, pH 7.4) was prepared using reagent-grade chemicals according to standard protocols.

Anil K. Philip, Betty Annie Samuel, Yagub S. Saleh, Saurabh Bhatia, Bassim I. Mohammad, Hayder A. Al-Aubaidy, pH-responsive agarose hydrogel for enhanced gastrointestinal ibuprofen delivery: A novel pressure-sensitive adhesive system, Next Materials, Volume 8, 2025, 100790, ISSN 2949-8228, https://doi.org/10.1016/j.nxmate.2025.100790.