Chroma-hue controllable color and thermocolor-added deoxyribonucleic acid films

Deoxyribonucleic acid (DNA) is a useful scaffolding material for the alignment of nanomaterials with specific functionalities. Here, we fabricated multi-layered (e.g., single, triple, and quintuple) color-added DNA films with a different color in each layer on substrates as well as a self-supported film with a mixture of different colors. A color-added DNA thin film on a substrate was prepared by either drop-casting or spin-coating, and a self-supporting DNA film was constructed by an oven-drying procedure. The optical characteristics of DNA films with various color dye concentrations were studied through transmittance and absorption. In addition, color profiles (i.e., chroma and hue angle) of the self-supporting DNA films were investigated by considering reflectance to obtain International Commission on Illumination LAB (CIELAB) values (where L, A, and B represent the brightness, x-axis (green-red), and y-axis (yellow-blue) in the CIE color space, respectively). Color profiles were obtained by L, A, and B. The chroma of the self-supporting DNA film with more colors were relatively small, indicating a dark achromatic characteristic of the samples. The hue angle of each film corresponded to the characteristic colors. Finally, the reversibility of the color change of DNA films embedded with thermochromatic dyes was demonstrated by varying the temperature to verify use in practical applications.