Production and characterization of chitosan-TPP/cellulose nanocrystal system for encapsulation: a case study using folic acid as active compound

The aim of the present study was to propose a new approach on the preparation of a hybrid system composed of chitosan nanoparticles (ChNps) and cellulose nanocrystals (CNCs), as carriers of folic acid (FA). ChNp was prepared by ionic gelation technique using sodium tripolyphosphate (TPP) as crosslinker and CNCs from soybean pods, extracted by chemical pre-treatments and acid hydrolysis. The microscopic observation revealed clusters of fibers amongst the ChNps, arranged in a three-dimensional network as large as 1 to 3 µm in diameter. Zeta potential measurements of the particle suspensions loaded with FA did not differ significantly from those read for empty ChNps (both samples with values around + 23 to + 25 mV). The CNC hybrid system presented higher efficiency of encapsulation (72 ± 8%), compared to cross-linked ChNp system which has no fibers added (62 ± 4%). Moreover, the FA releasing (at pH 3.0 and 7.4) and the protection against light degradation were higher in the hybrid systems. Infrared spectroscopic and thermogravimetric analysis showed a better maintenance of the main vitamin structure when encapsulated by the composite particles.