Role of manganese-based surfactant towards solubilization and photophysical properties of fluorescein

Abstract

Dye-surfactant interactions are being explored from various viewpoints over the years, in this work the interactions between fluorescein dye and manganese based water soluble surfactant were explored to modulate the photophysical properties of such photosensitizers in metal containing microheterogenous environment and evaluating their role in solubilization. For the purpose, manganese (Mn) surfactant complexes were prepared, in different ratios of metallic counter ion to number of hydrocarbon chains i.e. 1:1 and 1:2. The formulated complexes were further characterized by different techniques viz. Fourier transformed infra red spectroscopy (FTIR), elemental analysis, thermogravimetric analysis, and nuclear magnetic resonance (NMR). Thermal stability of manganese surfactant complexes and kinetics of decomposition were investigated. The effect of metallic counter ion and temperature was evaluated on the surface activity and aggregation of manganese surfactants, where presence of metal ion lowered the critical micellization concentration and also affected the packing of adsorbed molecules at air/solution interface. Our investigation further capitalized on the spectral sensitivity of fluorescein dye in pre and post micellar system of manganese surfactant complexes. The influence of manganese surfactant complexes on the photophysics of fluorescein dye was thoroughly evaluated using spectrofluorimetric parameters such as Stern-Volmer constant, binding constant and anisotropy. NMR was used to locate the binding site of dye molecules in metallomicelles. Fluorescence quantum yield and singlet oxygen quantum yield was estimated using comparative methods and increased fluorescence and singlet oxygen quantum yields were observed for dye on solubilization in metallomicelle as compared to conventional surfactant.

Fluorescein–Metal Hybrid Surfactant Conjugates as a Smart Material for Antimicrobial Photodynamic Therapy against Staphylococcus aureus

“…First, the solubility of FL is an important aspect in the cell medium because its insolubility decreases its binding with cellular material and that causes FL to fail in the photodynamic activity of S. aureus after irradiation. As observed in our previous work, 22 metallosurfactants enhanced the solubility of FL in an aqueous medium to prevent its aggregation. Also, the polar head group of metallosurfactants interacts with the bacterial cell walls and increases the permeability of the membrane, which leads to enhance uptake of FL molecules inside the cells.…”

“…aureus after irradiation. As observed in our previous work, metallosurfactants enhanced the solubility of FL in an aqueous medium to prevent its aggregation. Also, the polar head group of metallosurfactants interacts with the bacterial cell walls and increases the permeability of the membrane, which leads to enhance uptake of FL molecules inside the cells.…”

“…Chemicals. Manganese complexes (abbreviated as MnC I for the single-tail metallosurfactant and MnC II for double tail alkyl chain metallosurfactant) were synthesized according to the previously reported method 22 (Figure 1a). DPBF, tris(2,2′bipyridyl) ruthenium (II), Trizma base (99.9% purity), agarose, NaH 2 PO 4 , and Na 2 HPO 4 were purchased from Sigma-Aldrich.…”

“…In case of pure FL, generated singlet oxygen attack on the chromophore part of FL and results in the conversion into the nonflorescent product. In our previous work, we had observed that metallosurfactants increased the fluorescence intensity of FL which is due to the interaction of the dianionic form of the FL molecules with the metallosurfactant immensely through a balance of repulsive and attractive actions between hydrophobic and hydrophilic moieties. Because of this interaction, there are fewer chances or lesser sites that are available on FL for the binding of generated singlet oxygen which leads to the reduction of the photobleaching process.…”

Hybrid surfactants decorated with copper ions: aggregation behavior, antimicrobial activity and anti-proliferative effect

“…Further, the kinetics of decomposition was evaluated for step 1 at the transition temperature (T trans ), which was obtained from the TG curve (334 1C for Cucpc I and 253 1C for Cucpc II) using five methods, based on a single heating rate, i.e. Coats-Redfern (CR), Horowitz-Metzger (HM), Madhusudanan-Krishnan-Ninan (MKN), Van Krevelen (VK) and Wanjun-Yuwen-Hen-Cunxin (WYHC); 27 the details are provided in the ESI. † Although the insertion of copper into the complex, the decomposition temperature was delayed for both Cucpc I and Cucpc II.…”