Delivery and controlled release abilities of chitosan/carboxymethylcellulose micropolyelectrolyte complexes (PECs) toward niacinamide (vitamin B3).

The administration of bioactive compounds presents challenges due to the numerous physiological barriers in the gastrointestinal tract. To deal with one of these challenges, chitosan/carboxymethylcellulose micropolyelectrolyte complexes (micro-PECs) were developed without the use of crosslinking agents to carry niacinamide, a model hydrophilic bioactive agent. A Box-Behnken design was used to study the effects of processing time (X₁: 60, 120 or 180 min), pH (X₂: 3, 4 or 5) and niacinamide concentration (X₃: 0.02, 0.04 and 0.06, g·L^-1) on the encapsulation efficiency (Y₁) and loading capacity (Y₂) of niacinamide by CMC/CHS micro-PECs. The encapsulation efficiency (Y₁) varied from 0.86 % to 80.78 %, whereas the loading capacity (Y2) varied between 0.03 % and 3.89 %. The digestibility of CMC/CHS micro-PECs containing niacinamide was evaluated in vitro via a static gastrointestinal model. Empirical models (Zero Order, First Order, Higuchi and Korsemeyer-Peppas) were fitted to the niacinamide release kinetics data. The zero-order model exhibited the best fit across all points (gastric and enteric digestion), with low zero-order constants (K₀) ~ 0.002-0.003, indicating a regular and subdued release rate in all cases. These results highlight the applicability of CMC/CHS micro-PECs as an efficient, novel oral delivery system, surpassing conventional approaches by offering a sustained release and high encapsulation efficiency, without the need for complex crosslinking agents for their obtention.