In particular, cancer is one of major diseases in studies for gene delivery systems worldwide. Among them, breast cancer is a frequent malignancy worldwide and an important public health problem. In the past years, the molecular understanding of this disease has shed light into its heterogeneity. It is categorized into five groups: human epidermal growth factor receptor 2 [HER2] type, luminal A, luminal B, triple negative, and normal like, based on the cell surface and other molecular markers. The aim of this study is to improve transfection efficiency of gene carrier and to achieve targeted gene therapy for HER2-positive cancer cells, based on water-soluble chitosan (WSC) as a conjugating backbone biopolymer, synthetic peptides with Hexa-histidine-linear octa-arginine (HLR) or haxa-histidine-dendrimer octa-arginine (HDR) which is able to enhance nucleic acid-binding, proton sponge effect, and endosomal escape, LTVSPWY dendrimer peptide (Her2(d2)) which can target to HER2-positive cancer cells, and HnMc antimicrobial peptide which may be able to induce mitochondrial apoptosis.