Abstract

A multivariate approach that consists of a two-step design of experiments and partial least squares regression (PLSR) calibration was performed in order to synthesize a thiomer based on alginate-cysteine mediated by carbodiimide (EDAC). Five processing variables X1 type of alginate; X2 quantity of EDAC; X3 quantity of l-cysteine; X4 reaction temperature and X5 reaction time were studied along with two responses: Y1 amount of thiol groups (-SH) and Y2 disulfide bonds (-S-S-). A PLS quadratic model (P < 0.05) was obtained in the optimization step (R2 = 0.851 and Q2 = 0.570). A thiomer with a maximum amount of-SH groups of 503.87 μmol g-1 and a minimum formation of-S-S-bonds 260.17 μmol g-1 was obtained under the optimal synthesis conditions: Quantity of EDAC 0.82 g; quantity of l-cysteine 3.00 g; reaction time 1.0 h; reaction temperature 10 C; and using sodium alginate. The optimized thiomer showed the amount of-SH increased from 55 to 120% compared to previous reports on alginate-cysteine thiomers synthesized using the univariate method, and has elastic and viscous modulus more than 7-fold higher than the unmodified alginate obtained in in vitro mucoadhesive assays with mucin. This journal is