Mechanical characteristics of free-standing DNA thin films tuned by gold nanoparticles, metal and lanthanide ions

Abstract

DNA obtained from salmon fish exhibits outstanding characteristics such as low-cost, biodegradable, and non-toxic. Salmon DNA (SDNA) can be easily fabricated into free-standing thin films and functionalized by embedment of various nanomaterials such as gold nanoparticles (Au NP), metal ions (e.g., Cu2+) and lanthanide ions (e.g., Tb3+). Here, free-standing SDNA (FS-SDNA) and nanomaterial-embedded SDNA (FS-NM-SDNA) thin films by casting method were constructed and their tensile properties (e.g., stress-strain and Young's modulus) and dynamic mechanical properties (e.g., storage modulus (E′), loss modulus (E″) and tangent of phase angle (tan δ)) were studied. Young's moduli of FS-NM-SDNA thin films were significantly enhanced than those of FS-SDNA possibly due to doping of NMs and variation in water contents. Dynamic mechanical analysis (i.e., E′, E″ and tan δ) of FS-SDNA and FS-NM-SDNA thin films as a function of temperature (T) was also performed to understand stiffness and structural stabilities of samples. Noticeable peaks in E″ were assigned to characteristic transition temperatures of FS-SDNA and FS-NM-SDNA such as β-transition, water evaporation, structural deformation and α-transition temperatures. Finally, differences in E′, E″ and tan δ at a given unit T (i.e., ΔE'/ΔT, ΔE''/ΔT and Δtan δ/ΔT) were analysed to better understand the transition mechanism.