Physicochemical characteristic of piperine-loaded sodium caseinate-zein nanoparticles coated with charged polysaccharides

This study investigated the physicochemical properties and stability of piperine-loaded sodium caseinate–zein nanoparticles (SCZP) coated with charged polysaccharides, gum Arabic (GA-SCZP, anionic) or chitosan (CT-SCZP, cationic), to enhance the oral delivery of piperine. SCZP were prepared by antisolvent precipitation and subsequently coated via polysaccharide deposition, achieving encapsulation efficiencies above 95%. Particle size and zeta (ζ) potential varied depending on the type and concentration of the polysaccharide coating. SEM confirmed that the nanoparticles possessed a spherical morphology, while XRD and DSC analyses verified the successful incorporation of piperine into the nanoparticle matrix. Under simulated gastrointestinal (GI) digestion, SCZP significantly improved piperine stability compared with free piperine, and the type of polysaccharide coating influenced the piperine retention rate. CT-SCZP exhibited the highest intestinal piperine retention, showing a 2.19-fold increase compared with free piperine, reflecting enhanced stability and potential bioaccessibility. These results demonstrate that electrostatic interactions driven by polysaccharide charge influence nanoparticle physicochemical properties and digestive stability. Overall, cationic CT-coated SCZP provides a promising strategy for improving the stability and intestinal delivery of lipophilic bioactives such as piperine.