Medium molecular weight chitosan (CS; 75–85% deacetylated), 3-aminopropyltriethoxysilane (APTES; 99% purity), sodium hydroxide (NaOH), acetic acid, and RB4 were all supplied by Sigma-Aldrich, Malaysia and were used as received without further purification. All of the chemicals used were of analytical grade. Distilled water was used for all dilution purposes and solution preparations.