High oxidative stability of a complex fish liver oil nano-capsules in response to long-term storage, and to hyperthermal and sunlight exposure.

Abstract

In this study, a biocompatible nano-carrying platform using chitosan (ChI) and chondroitin sulfate (ChS) was developed for the encapsulation of cobia liver oil (CBLO) to prevent its oxidation and improve its absorption. An ionic gelation method was applied to encapsulate CBLO with different weight ratios (from 1.0 to 1.5) to obtain ChS-ChI nano-capsules (ChS-ChI@CBLO NCs). Morphological observations of the nano-capsules revealed a spherical shape and diameter around 267-381 nm. The maximum loading capacity (LC) and encapsulation efficiency (EE) for ChS-ChI@CBLO NCs estimated by thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) analysis were 25.7% and 56.2%, respectively. The structural stability of ChS-ChI@CBLO NCs was confirmed through differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis; moreover DSC also further confirmed the oxidative stability of ChS-ChI@CBLO NCs. Fourier-transform infrared (FTIR) spectra confirmed the excellent stability of ChS-ChI@CBLO NCs against high temperature and sunlight exposure. Biocompatibility analysis also verified the non-toxicity of ChS-ChI@CBLO NCs, further indicating safety and potential application in complex-nutritional supplements. Nano-degree of ChS-ChI@CBLO NCs has a loading capacity and encapsulation efficiency of around 16.5 ~ 25.7% and 33.4 ~ 56.2%, respectively, for encapsulation of CBLO. Characterization results also indicate that ChS-ChI@CBLO NCs display high oxidative stability against long-term, hyperthermal, and sunlight exposure. Bioassay results confirm that the ChS-ChI@CBLO NCs are safe and non-toxic. This study demonstrates that nano-capsules are also beneficial in preventing sensitive compounds from metamorphosis, and are non-toxic. These materials are suitable for use in the food and pharmaceutical industries. © 2023 Society of Chemical Industry.