Taking orders from light: progress in photochromic bio-materials

Photochromic materials are a family of compounds which undergo photo-reversible transformations between two different isomers with distinct physical and chemical properties. Most smart photochromic materials have been exploited in research areas such as electro-optical functional materials, while recently their applications have extended to novel bio-materials. Biological systems, such as tissue/cellular imaging, nucleotides, peptides, ion channels, etc., have emerged as a revolutionary research frontier for photochromic materials since both covalent coupling and non-covalent interactions with bio-molecules have been achieved. This review commences with a brief description of exciting progress in this field, and describes strategies for using photochromic functional molecules from bio-sensing and cell imaging to optical manipulation of bio-macromolecules (nucleotides, peptides, ion channels, GFP, etc.). Further development of these photo-switches as well as remaining challenges are also discussed and put in prospect.