Casein-functionalized manganese ferrite nanostructures for selective extraction of carotenoids from Rhodotorula...

A magnetic extraction/recovery platform for carotenoids was developed using casein-functionalized, chitosan-coated MnFe₂O₄ nanoparticles (Cas@CSMNP). Nanoparticles were prepared by coprecipitation followed by hydrothermal treatment and characterized by XRD, FTIR, DLS, TGA, TEM, and magnetometry, confirming a spinel core and successful casein coating. A design-of-experiments approach identified conditions that maximized casein immobilization (80 mg g⁻¹ at 40 °C) consistent with favorable kinetic/isotherm fits. The results of assays with β-carotene standards and Rhodotorula toruloides extracts showed rapid uptake, with 73.1% and 84.2% adsorption, respectively, after 1 h at 30 °C. Cell-viability assays (1132 SK, RAW 264.7) indicated > 90% viability at 50-100 µg mL⁻¹. Cas@CSMNP integrates protein affinity with magnetic separability under ethanol-compatible conditions, providing a practical, potentially solvent-saving route for selective recovery of carotenoids from yeast extracts and a foundation for future evaluation of desorption and reuse.