Perspectives on the pH-Influenced Design of Chitosan–Genipin Nanogels for Cell-Targeted Delivery

Abstract

Background: Chitosan (CS) crosslinked with genipin (GNP) provides a mild, nontoxicroute to generate nanogels (NGs) with enhanced integrity and colloidal stability.Objectives: To develop and characterise CS-GNP NG as a novel platform for targetedcellular delivery, optimising design through physicochemical characterisation and biocompatibilityevaluation. Methods: NGs were synthesised under optimised conditionsby adjusting the pH of the CS solution, followed by high-intensity ultrasound (HIUS) toachieve disaggregation. Physicochemical characterisation was carried out using UV-Visspectroscopy, FTIR, dynamic light scattering (DLS), and scanning electron microscopy(SEM). Rheological studies and SAXS analysis assessed structural properties. Biocompatibilitywas evaluated via MTT assay, and internalisation was monitored by fluorescencemicroscopy on mammalian cell lines. Results: NG formation was highly pH-dependent,with optimal configuration at pH 4.5, yielding stable, uniformly sized particles (~200 nm,ζ-potential +29 mV). Kinetic modelling showed a sigmoidal formation pattern, suggestingnucleation, growth, and stabilisation. FTIR confirmed covalent bonding between CSand GNP via primary amide bonds and Schiff bases. Rheology indicated pseudoplasticbehaviour, and SAXS revealed a compact network formation. Biocompatibility assaysconfirmed non-cytotoxicity below 100 μg/mL and efficient cellular uptake. Conclusions:This study presents a rapid, reproducible protocol for generating colloidally stable, biocompatibleNGs suitable for drug delivery.