Experimental and first-principles investigation of the adsorption and entrapping of guanine with SiO₂clusters of sol–gel silicate material for understanding DNA photodamage

Abstract

We report a first principles density functional theoretical (DFT) investigation of guanine (G) adsorption onto SiO2 clusters, viz., Si2O4, Si3O6, Si4O8 and Si5O10 in terms of geometry, binding energy (EB), binding site, energy gap (Eg), and electronic and spectral properties. Guanine entrapped within a Si9O18 cluster was also studied in terms of geometry, energy gap (Eg), electronic and spectral properties. We observed that the most stable forms of the cluster were Si5O10 and Si9O18. Guanine adsorbed onto SiO2 (G-SiO2) and guanine entrapped within SiO2 (GE-SiO2) were analyzed by the B3LYP/LanL2DZ method. The HOMO-LUMO energies illustrate that charge transfer from ligand to metal (L → M) occurs in G-SiO2 clusters as guanine to SiO2. The composite of guanine with nanostructured silica material was prepared by simple precipitation and chemical sol-gel processes. The prepared G-SiO2 and GE-SiO2 composites were characterized by FT-IR and FE-SEM with EDX analysis. The resulting experimental evidence is included for better understanding the guanine adsorption and entrapment. The adsorption and entrapping of G-SiO2 and GE-SiO2 was also confirmed by UV-vis spectroscopy. Experimental results are compared with the DFT results. Furthermore, the sol-gel silicate material used to protect the DNA base (guanine) from UVA-irradiation has been highlighted.

Selective Adsorption and Photocatalytic Degradation of Extracellular Antibiotic Resistance Genes by Molecularly-Imprinted Graphitic Carbon Nitride

“…The two absorption peaks at 1120 and 952 cm −1 are assigned to C− C stretching vibrations. 49 These specific peaks from guanine were identified from FTIR spectra of as-obtained MIP-C 3 N 4 before acid washing, indicating that guanine molecules were imprinted into the MAA polymer matrix. As expected, the guanine adsorption peak at 1692 cm −1 was prominent before (but barely present after) the polymer was washed with HCl, and both MIP-C 3 N 4 and NIP-C 3 N 4 had similar FTIR spectra because of similar surface functional groups.…”

“…The imprinting of guanine was demonstrated through peak identification from the FTIR spectrum (Figure 1d). 49 The FTIR spectrum of guanine shows a broad absorption in the range of 3000 to 3300 cm −1 corresponding to OH group vibrations. Another four peaks at 2906, 1692, 1563, and 1373 cm −1 were also identified from the spectra of guanine, respectively, representing C−H stretch, N−H stretch, CC stretch, and the C−H deformation vibrations.…”

“…The imprinting of guanine was demonstrated through peak identification from the FTIR spectrum (Figure d) . The FTIR spectrum of guanine shows a broad absorption in the range of 3000 to 3300 cm –1 corresponding to OH group vibrations.…”

Silicate Matrix with Implanted Peptide Self-Assemblies for Smart Sensor Electrodes and Coated Glass Systems

“…Reduction in the intensity is also shown by the BTTPNTs implanted SiO2 matrix. So when BTTPNTs implanted inside the silicate shell it is showing a broad absorption band [23]. Fig.…”

“…Silicate surface promotes a wide range of surface reactions to produce an active peptide based catalyst [22]. The physical confinement of biomolecules within the porous matrix, provides applications in bioanalytical, biotechnological and biomedical industries [23,24]. The results are focused on the shielding of biomolecules to protect them and to create a single entity [22].…”