Terin Adali

Spectroscopic Characterization of PEG-DNA Biocomplexes by FTIR

Understanding the mode involved in the binding of certain molecules to DNA is of prime importance, and PEG offers wide-ranging applications in biological, medical and pharmaceutical contexts. FTIR spectroscopy has been used to characterize how the formed biocomplexes bind or dissociate to/from each other between PEG400-ctDNA under different conditions. Characterization and investigation of the effect of incubation time on PEG400-ctDNA biocomplexes formation were studied through spectroscopic technique FTIR. The influence of time duration and incubation on intermolecular interaction was analysed at three different selected times (Zero, 1hr, and 48 hrs.) at 1:1 PEG400-ctDNA monomer to nucleotide ratio. The experiment was carried out at room temperature 22 °C, with prior vortex stirrer of biocomplex for 10 min to improve homogeneity of sample. The results showed that the binding reaction of PEG400-ctDNA proceeds rapidly through DNA base pairs and phosphate DNA backbone, and complexation was reached after a maximum 1hr after mixing PEG400 and ctDNA at 1:1 ratio. FTIR spectroscopy results suggest that PEG400 binds with ctDNA by weak to moderate biocomplexes formation, with both hydrophilic and hydrophobic contact through DNA base pairs, with minor binding preference towards phosphate backbone of DNA helix. The mode of interaction most likely referred to an interaction through outside groove binding or electrostatic binding modes. FTIR highlighted the significant effect of incubation time on the stable biocomplexes of non-ionic PEG400 and ctDNA. Moreover, FTIR spectroscopy technique was rapid, showed good stability, and is a valuable tool for studying the biological properties of biocomplexes of PEG400 and ctDNA.

Peg-calf thymus dna interactions: conformational, morphological and spectroscopic thermal studies

The main aim of this study is to provide understanding for the interaction modes and the binding affinity based on the study of PEG 400 that binds to ctDNA. The effects of the PEG-400-to-ctDNA ratio, pH, incubation time and thermal stability of ctDNA on PEG-ctDNA biocomplex formation were studied. UV-vis-NIR absorption analysis indicated that PEG forms a complex with ctDNA via a mechanism other than intercalation. The results of thermal denaturation studies showed that the PEG-ctDNA biocomplex helix was stabilised, with a resulting increase in the PEG-ctDNA melting temperature. FTIR analysis indicated that the PEG binds to ctDNA through weak to moderately strong hydrophilic and hydrophobic interactions with the base pairs of ctDNA. TEM micrographs showed that the addition of PEG to ctDNA caused ctDNA to condense with PEG molecules into an irregular aggregate structure. These results demonstrate that the PEG-ctDNA biocomplex has potential applications in biomedical sciences.

Synthesis and characterization of noncytotoxic and biodegradable polymethacrylates-grafted chitosan gels

Poly(methacrylates), namely 2-hydroxy ethyl methacrylate (HEMA), ethylene glycol dimethacrylate (EGDMA) and triethylene glycol dimethacrylate (TEGDMA) were grafted onto chitosan by using ceric ammonium nitrate as a redox initiator. Semi-IPN gels of chitosan-graft-poly(HEMA)-graft-poly(EGDMA) and chitosan-graft-poly(HEMA)-graft-poly(TEGDMA) were obtained. The grafting conditions were optimized with respect to monomer concentrations. The products were characterized by TGA, FTIR, XRD and SEM techniques. The solubility of the grafted products in aqueous medium decreased with increasing grafting percentage. The insoluble gels exhibited a highly pH sensitive swelling behaviour. TGA thermograms showed that poly(HEMA)/poly(TEGDMA)-grafted product is much more stable than poly(HEMA)/poly(EGDMA)-grafted product showing that TEGDMA is a more effective crosslinker than EGDMA. According to XRD analysis TEGDMA has a higher tendency to form ordered structures than EGDMA as it is capable of chain folding. The results of cytotoxicity studies revealed that the methacrylate-grafted chitosans were noncytotoxic and good candidates for biomedical applications.