Positively and Negatively Charged Collagen Nanohydrogels: pH‐responsive Drug‐releasing Characteristics

Researchers are facing many challenges in developing a strategy for site‐specific delivery in the gastrointestinal tract that can maximize therapeutic response and reduce side effects. The objective of this article was to develop a site‐specific drug delivery system for the gastrointestinal tract using natural polymer collagen (CG). For this, two types of pH‐responsive CG nanohydrogels (negatively charged pH‐CGNH‐COOH and positively charged pH‐CGNH‐NH 2 ) were prepared using negatively and positively functionalized carbon nanotubes, CNT‐COOH and CNT‐NH 2 , respectively. The pH‐CGNH‐COOH and pH‐CGNH‐NH 2 nanohydrogel samples comprising negatively and positively charged fibrils (CG/CNT‐COOH and CG/CNT‐NH 2 ) were physicochemically characterized by Fourier‐transform infrared spectrometry, Zeta sizer, thermogravimetric analysis, and field emission scanning electron microscopy. They also revealed the pH‐responsive release of bovine serum albumin at pH 9 and cytochrome C at pH 2. These results strongly indicate that these drug carriers can be useful for site‐specific delivery in the gastrointestinal tract.