Interaction Behavior of DNA with Halloysite Nanotube-Silver Nanoparticle-Based Composite

We report the use of novel silver nanoparticle-immobilized halloysite nanotube (AgNP-HNT) composites to determine their ability to detect DNA damage. Naturally occurring tubular structures such as HNTs act as support matrices for the formation of AgNPs in the presence of neem broth as reducing agent and silver nitrate (AgNO3) as precursor. The tubular structure of halloysite nanotubes allowed the AgNP formation on their surface to derive AgNP-HNT composites. These AgNP-HNT composites were characterized by using scanning electron microscopy, energy-dispersive analysis attachment (energy-dispersive X-ray fluorescence), and differential scanning calorimetry (DSC). We further confirmed the DNA binding capacity of AgNP-HNT composites by DSC and further characterized their role in sensing DNA damage. Here, we have demonstrated the difference in electrostatic properties of single- and double-stranded oligonucleotides (ss-DNA and ds-DNA) with AgNP-HNT composites using spectrophotometry and spectrofluorometry. We observed that as the binding of ds-DNA or ss-DNA with silver nanoparticles increased, there was a concurrent increase in the absorption which was characterized with the decrease in fluorescence intensities. Our studies show the possibility of using this AgNP-HNT composite not only for enhancement of the shelf life of AgNPs but also to give an edge to use this technology for many biological and medical applications © 2012 Springer Science+Business Media New York.