cationic

Cationic describes anything bearing a net positive electric charge. In chemistry, a cation is an atom or molecule that has lost one or more electrons, resulting in a positive charge. Cations are present in solutions with anions and balance charge through electrostatic interactions; common inorganic cations include Na+, K+, Ca2+, and NH4+. Anions carry negative charges. The term cationic can also refer to species or materials that are positively charged, such as cationic polymers or cationic surfactants. Cationic polymers contain positively charged groups along their chains (for example, protonated amines or quaternary ammonium groups) and are used to interact with negatively charged surfaces, in water treatment to aid flocculation and in gene delivery as carriers. Cationic surfactants have a positively charged head and are widely used in detergents, personal care products, and disinfectants.

In biology and biochemistry, many biomolecules carry positive charges; the side chains of lysine and arginine are positively charged at physiological pH, and histidine can be partially charged depending on conditions. Cationic peptides are studied for antimicrobial activity and membrane interactions, while cationic lipids and polymers serve as non-viral vectors for nucleic acid delivery. The opposite of cationic is anionic, referring to negatively charged species.