Irreversible denaturation of DNA: a method to precisely control the optical and thermo-optic properties of DNA thin solid films

Abstract

The denaturation of double-stranded deoxyribonucleic acid (ds-DNA) has been well known to break nucleobase bonds, resulting in single-stranded deoxyribonucleic acid (ss-DNA) in solutions, which can recombine to form ds-DNA in a reversible manner. We developed an efficient process to irreversibly maintain various DNA denaturation levels in thin solid films in order to investigate the impacts of the denaturation on the optical properties of DNA films. By adding NaOH in an aqueous solution of salmon testis DNA, we flexibly controlled the level of denaturation in the solution, which was then spin-coated on Si and silica substrates to irreversibly bind ss-DNAs in a thin solid film. The denaturation of DNA in thin solid films was experimentally confirmed by ultravioletvisible and Fourier transform infrared spectroscopic investigations, whose level could be controlled by the NaOH content in the aqueous solution precursor. By this irreversible denaturation process, we developed a new method to flexibly vary the refractive index of DNA thin solid films in a wide range of Δn > 0.02 in the visible to nearinfrared range. Thermo-optic coefficients dn/dT of the films were also experimentally measured in the temperature range from 40°C to 90°C to confirm the significant impacts of denaturation. Detailed thin film processes and optical characterizations are discussed.

Linear and nonlinear optical properties of transfer ribonucleic acid (tRNA) thin solid films

“…An increase of absorption in TSF compared to the solution precursors has also been observed in DNA. 4,6 In (Table 1), we also summarized how the thin lm thickness could be controlled by the tRNA concentration in the precursor solution. The lm thickness was exibly controlled in the range of 30 to 46 nm, and it monotonically increased with tRNA concentration.…”

“…Deoxyribose nucleic acid (DNA) has recently shown prominent potential as a highly functional electro-optic material. 1,2 Thin solid lms (TSFs) made from either DNA aqueous solutions 3 or other organic solutions [4][5][6][7] have found unique optoelectronic applications. For instance, DNA-TSF has been used as an electron blocking layer in organic light-emitting diodes (OLEDs), 8,9 hydrogen-blocking layer in hybrid thin-lm transistors (TFTs), 10,11 a cladding layer in an optical waveguide modulator, 12 a sensing medium in optical sensors, 13,14 a nonlinear saturable absorber in femtosecond lasers, 3 and a radiation absorbing layer in solar cells, 15,16 to name a few.…”

“…In this study, we report a systematic process to fabricate tRNA TSFs with various thicknesses on both silicon (Si) and silica substrates using a surfactant-free aqueous solution of tRNA from wheat germ, 6,10 for the rst time. We further analyzed their linear optical properties in terms of absorption, a, in the UV-VIS-NIR spectral range, linear refractive index, n(l), in the visible to NIR from 400 to 900 nm, and thermo-optic coefficient, dn/dT, in the temperature range from 40 to 90 C. Utilizing these linear optical properties, we furthermore investigated the nonlinear refractive index, n 2 , and the nonlinear absorption, b, using a femtosecond laser Z-scan technique, 30 revealing the high potential of tRNA TSF in nonlinear optical applications.…”

Solvent Effect to the Uniformity of Surfactant-Free Salmon-DNA Thin Films

“…UV–VIS analysis indicates that there is no significant absorbance peak shift in DNA regardless of the existence or choice of solvent ( Figure 7 ). This is expected from previous research [ 20 , 30 , 39 ]; however, methanol, ethanol, and isopropanol exhibit different magnitudes in the peaks of DNA, and acetone solution is not graphed here since it exhibits a hard UV cutoff where the expected DNA peak is. Methanol and ethanol produce peaks of similar magnitude, while isopropanol produces a noticeably lower peak.…”

“…Therefore, a lower Std/Ave corresponds to higher uniformity. We observed that pure water-DNA solutions created large sample-to-sample variation, which can be caused by uneven distribution of the solution onto silicon wafers and minor misalignment of the wafers, and relative humidity can be a significant factor in film formation by spin coating [37][38][39]. The two data sets in Tables 1 and 2 demonstrate that pure aqueous-based…”