Comparative study of calf-thymus DNA complexation by low generation PAMAM dendrimers and linear cationic PEGylated block copolymers by time-resolved fluorescence spectroscopy

Histidine-Based Reduction-Sensitive Star-Polymer Inclusion Complex as a Potential DNA Carrier: Biophysical Studies Using Time-Resolved Fluorescence as an Important Tool

“…On the other hand, the lifetimes of the shorter component were varied from ∼0.90 to 0.50 ns for lower N/P ratios ranging from 0.4 to 1.2. This observation is well supported by our previous research, where we have hypothesized that at lower charge ratios, dislodged EB molecules were not completely separated from polyplexes but were weakly bound to the polyplexes. At higher N/P ratios, the lifetimes of the shorter components stayed almost unchanged (∼0.30 ns), which were close to the values for free TO in the absence of DNA.…”

“…Steady-state as well as time-resolved fluorescence spectral studies to evaluate the DNA binding ability of different cationic DNA carriers are usually done using the EB dye. ,,− However, because of the limited ability of EB to augment fluorescence intensity on binding with DNA, all these fluorescence studies using EB were carried out at very high concentrations of DNA. For example, Dey et al showed that the fluorescence intensity of EB increased only around 10 times from free EB to EB–DNA complexes using the concentration of calf thymus DNA at 25 μM (in terms of phosphate groups present in the DNA backbone) and the ratio of the concentrations of EB and the nucleotide was maintained as 1:15.…”

“…Steady-state as well as time-resolved fluorescence spectral studies to evaluate the DNA binding ability of different cationic DNA carriers are usually done using the EB dye. ,,− However, because of the limited ability of EB to augment fluorescence intensity on binding with DNA, all these fluorescence studies using EB were carried out at very high concentrations of DNA. For example, Dey et al showed that the fluorescence intensity of EB increased only around 10 times from free EB to EB–DNA complexes using the concentration of calf thymus DNA at 25 μM (in terms of phosphate groups present in the DNA backbone) and the ratio of the concentrations of EB and the nucleotide was maintained as 1:15. However, importantly, these concentrations of DNA are much higher than that used for in vitro or in vivo gene transfections which generally have a value of 1 μg/mL (i.e., ∼3.2 μM) .…”

“…Nowadays, the time-resolved fluorescence spectroscopy method has been an interesting as well as useful tool to investigate the state of DNA inside the polyplexes. − This particular methodology certainly allows disengaging the fluorescence lifetime and amplitude. Also, this technique is not obstructed by scattering, consequently enabling quantitative analysis to a greater extent.…”

Redox-Responsive Efficient DNA and Drug Co-Release from Micelleplexes Formed from a Fluorescent Cationic Amphiphilic Polymer

“…In the past, we have studied the complex formation of DNA with cationic polymers of various architectures using various biophysical techniques. It was found that the presence of hydrophilic segments along with the cationic part in the copolymers effected more condensation of DNA compared to only the cationic part. − We believe that it is equally important to probe the complexation behavior of DNA and cationic polymeric micelles with and without drug encapsulation, which leads to the formation of micelleplexes. A detailed biophysical characterization of the micelleplexes in vitro is important in gaining greater insight into the nature of the complex formation.…”