page_title: PH-sensitive polymers
section_title: Natural polymers
hierarchical_section_title: PH-sensitive polymers / Types / Natural polymers
context_page_description: pH sensitive or pH responsive polymers are materials which will respond to the changes in the pH of the surrounding medium by varying their dimensions. Materials may swell, collapse, or change depending on the pH of their environment. This behavior is exhibited due to the presence of certain functional groups in the polymer chain. pH-sensitive materials can be either acidic or basic, responding to either basic or acidic pH values. These polymers can be designed with many different architectures for different applications. Key uses of pH sensitive polymers are controlled drug delivery systems, biomimetics, micromechanical systems, separation processes, and surface functionalization.
context_section_description: Although many sources talk about synthetic pH sensitive polymers, natural polymers can also display pH-responsive behavior. Examples include chitosan, hyaluronic acid, and dextran. Chitosan, a frequently used example, is cationic. Since DNA is negatively charged, DNA could be attached to chitosan as a way to deliver genes to cells.  Natural polymers have appeal because they display good biocompatibility, which makes them useful for biomedical applications. However, a disadvantage to natural polymers is that researchers can have more control over the structure of synthetic polymers and so can design those polymers for specific applications.
caption: Chemical structure of Chitosan