Adsorption kinetics of aristolochic acid onto chitosan particles prepared via inverse emulsion method and evaluation of their biological activities in zebrafish.

Chitosan (CS), a polysaccharide with known adsorption properties, has been reported to effectively remove various environmental toxins, such as metal ions and pesticides. Aristolochic acid (AA) is a well-known nephrotoxin closely associated with nephropathy in both animal models and humans. In this study, crosslinked CS particles were synthesized via an inverse emulsion method and evaluated for their AA adsorption capability using UV-visible spectrophotometry. The CS particles exhibited efficient AA adsorption, with the equilibrium adsorption capacity increasing at lower pH and temperature. The adsorption behavior was better fitted by the Langmuir isotherm model within the tested concentration range, while the adsorption kinetics was better described by the pseudo-first-order model, yielding a rate constant of 0.065 (1/min) at pH 5.5 and 35 °C. Thermodynamic analysis revealed the adsorption was exothermic with a ΔH value of -17.15 kJ/mol, while the free energy change ΔG was negative, suggesting that the adsorption process was thermodynamically favorable under the tested experimental conditions. To evaluate the biological relevance of this system, a green fluorescent kidney-specific zebrafish line, Tg (wt1b:EGFP), was used to assess the renal toxicity. Direct exposure to AA resulted in approximately 86% of renal malformation. In comparison, the adsorption of AA by CS particles significantly reduced the malformation rate to 51.7%, demonstrating the potential of CS-based adsorbents to mitigate AA-induced toxicity and improve zebrafish survival. These results highlight the feasibility of using crosslinked CS particles as a promising adsorbent material for AA toxicity mitigation and kidney protection.