Optical dispersion control in surfactant-free DNA thin films by vitamin B2 doping

Bjorn Paulson,Inchul Shin,Kyunghwan Oh,Woohyun Jung,Reza Khazaeinezhad,Boram Joo,Hoi-Youn Lee,Byungjoo Kong,Sungha Park,Hayoung Jeong,Sreekantha Reddy Dugasani

doi:10.1038/s41598-018-27166-x

Abstract

A new route to systematically control the optical dispersion properties of surfactant-free deoxyribonucleic acid (DNA) thin solid films was developed by doping them with vitamin B2, also known as riboflavin. Surfactant-free DNA solid films of high optical quality were successfully deposited on various types of substrates by spin coating of aqueous solutions without additional chemical processes, with thicknesses ranging from 18 to 100 nm. Optical properties of the DNA films were investigated by measuring UV-visible-NIR transmission, and their refractive indices were measured using variable-angle spectroscopic ellipsometry. By doping DNA solid films with riboflavin, the refractive index was consistently increased with an index difference Δn ≥ 0.015 in the spectral range from 500 to 900 nm, which is sufficiently large to make an all-DNA optical waveguide. Detailed correlation between the optical dispersion and riboflavin concentration was experimentally investigated and thermo-optic coefficients of the DNA-riboflavin thin solid films were also experimentally measured in the temperature range from 20 to 85 °C, opening the potential to new bio-thermal sensing applications.

Highlights

Bio-compatible photonic materials are being intensively investigated for their high potential in biomedical detection, monitoring, and therapeutic applications[1,2]
For riboflavin-doped deoxyribonucleic acid (DNA) films, we found a larger optical anisotropy, which suggests that the riboflavin assists in the horizontal orientation of DNA thin films
A new method to systematically control the optical dispersion and thermo-optic properties of surfactant-free DNA thin films was developed by doping them with vitamin B2, known as riboflavin

Summary

Introduction

Bio-compatible photonic materials are being intensively investigated for their high potential in biomedical detection, monitoring, and therapeutic applications[1,2]. We experimentally demonstrated a new route toward systematic, consistent, and repeatable control of the refractive index of a surfactant-free DNA thin solid film by doping DNA with riboflavin, known as vitamin B2, for the first time to the best knowledge of the authors. This unique method may provide new potential all-DNA photonic devices that are inherently bio-compatible to be used in various applications embeddable in living tissues. Riboflavin has recently shown an optical gain[24,25] in gelatins, so that all-DNA active solid state devices could be further pursued by utilizing this new method

Methods

Results

Discussion

Conclusion