Engineering functional halloysite nanotubes via dual-biopolymer interfacial assembly for pH-responsive antibiotic delivery

Abstract

Localized, pH-responsive drug delivery systems offer an effective strategy to enhance antibiotic efficacy and overcome the limitations of conventional systematic therapies for chronic infected wounds. In this study, functional halloysite–chitosan–xanthan gum (HNT–CS–XG) nanocomposites were engineered for the controlled release of minocycline (MC). The dual-biopolymer modification produced a hybrid interface on HNTs, not previously explored. The interfacial interactions established between chitosan, xanthan gum and the HNT surface generated a unique cohesive interfacial network that resulted in mechanical integrity and pH-responsive behavior, central to the design of advanced functional materials. Comprehensive physiochemical characterization (FTIR, XRD, zeta potential, TGA, DLS, SEM, and TEM) confirmed successful surface modification, strong polymer–polymer interactions, higher dispersion stability and preservation of the tubular structure of the halloysites. Among the formulations with different ratios, 2:1:2 ratio of HNT:CS:XG,HNT–CS–600XG exhibited optimal particle size (442 nm), excellent dispersion stability (PDI = 0.071) and high drug encapsulation (EE = 33%), offering a favourable balance between colloidal stability and bio-interface compatibility. In-vitro release studies for the nanocomposites, compared to halloysites alone, demonstrated a sustained and pH-responsive behavior, with significantly higher release at alkaline pH (43%) relative to acidic conditions (19%) proven advantageous for chronic infection. Kinetic modeling for MC release followed first-order and Korsmeyer–Peppas models, suggesting a diffusion-controlled mechanism. This observation arises from the hierarchical transport barriers created by the polymer-nanotube interface. The results highlight the potential of HNT–CS–XG as a biopolymer-based framework for prolonged and targeted antibiotic delivery.