Abstract
ZnOāSiO2 composite films doped with La3+ ions (0.1%ā5.0% mass.) were obtained using the solāgel method. The absorption and ultraviolet luminescence spectra of the films, as well as the change in spectral characteristics under the influence of DNA, were studied. Doping of ZnO:SiO2 films with La3+ ions leads to an increase in the transmittance in the UV range (Ī» = 357 nm) from 4.5% (for undoped films) to 32%ā34%, and the transmittance is inversely proportional to the amount of dopant. In all doped films, the optical band gap increases in comparison with undoped films (3.35 eV) and amounts to 3.830ā3.853 eV. The application of DNA to the surface weakly affects the value of optical band gap. The maximum of the ultraviolet luminescence (UVL) band in ZnO:SiO2:La3+ films is slightly shifted depending on the amount of dopant and is located at Ī»em = 363ā367 nm. An increase in UVL intensity was observed upon doping by a factor of 8.4ā9.6 compared to ZnO:SiO2 films. A change in the amount of dopant does not lead to sharp changes in the magnitude of the intensity. Thus, the UVL intensity (Ī»ex = 260), compared with films with 0.1% La3+ content, varies by 5%ā11%. The effect of small amounts of DNA was studied for films doped with La3+. In the case of ZnO:SiO2:La3+, both extinguishing (up to 12%) and ignition (up to 5%) of UVL were observed. Monotone dependencies (which are desirable for the biosensor sensing element) were obtained for samples with La3+ 0.1 and 1.0% content. SEM images show that the images for zinc oxide are white crystallites of different sizes: from 0.5 Āµm to conglomerates of crystallites ā1 Āµm. In the presence of DNA, the surface structure changes due to the formation of rhomboid structures, whose sizes vary from 3 Āµm to 35 Āµm. It is known that lanthanum ions induce the compaction of DNA with the formation of nanoscale structures.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have