Water-Based Chitosan for Thymine Conjugation: A Simple, Efficient, Effective, and Green Pathway to Introduce Cell Compatible Nucleic Acid Recognition

Chitosan is a potential biopolymer for cell recognition and targeting; however, when those functions are based on cationic amine groups of chitosan, cell damage is a concern. This study presents water-based chitosan conjugated with thymine (CsT) through a mild and homogeneous conjugating reaction via amide bond without the use of organic and/or acidic solvents. The CsT displays water-solubility in a wide range of pH. A series of comparative gel retardation assays confirm the selective binding with poly(A), resulting in nanoparticles of 100 to 250 nm in size. PrestoBlue cell-viability assay clarifies nontoxicity and reveals noncytotoxicity to normal colon cells but inhibition of colon cancer cells. This simple pathway for water-soluble chitosan nucleic acid leads to synergistic effects of cell compatibility and DNA recognition.