Nile Red Synchronous Scan Fluorescence Spectroscopy to Follow Matrix Modification in Sol–Gel Derived Media and its Effect on the Peroxidase Activity of cytochrome c

Rei, Ana; Ferreira, Miguel; Hungerford, Graham

doi:10.1007/s10895-008-0353-y

Cited by 6 publications

(8 citation statements)

References 37 publications

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“…The free dye NR shows a blue-shift in absorption and fluorescence emission bands when going from a polar to an apolar solvent (Figure and Table S1). , A similar blue-shift can be observed when comparing absorption and emission spectra of NR and CMS/NR nanotransporters in H 2 O . Hence, the hydrophobic dye NR incorporated into the CMS nanocarrier used here experiences a local environment comparable to a more apolar solvent compared to water and is presumably shielded from interactions with the aqueous solvent.…”

Section: Resultssupporting

confidence: 70%

Nanodynamics of Dendritic Core–Multishell Nanocarriers

et al. 2014

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The molecular dynamics of polymeric nanocarriers is an important parameter for controlling the interaction of nanocarrier branches with cargo. Understanding the interplay of dendritic polymer dynamics, temperature, and cargo molecule interactions should provide valuable new insight for tailoring the dendritic architecture to specific needs in nanomedicine, drug, dye, and gene delivery. Here, we have investigated polyglycerol-based core-multishell (CMS) nanotransporters with incorporated Nile Red as a fluorescent drug mimetic and CMS nanotransporters with a covalently bound fluorophore (Indocarbocyanine) using fluorescence spectroscopy methods. From time-resolved fluorescence depolarization we have obtained the rotational diffusion dynamics of the incorporated dye, the nanocarrier, and its branches as a function of temperature. UV/vis and fluorescence lifetime measurements provided additional information on the local dye environment. Our results show a distribution of the cargo Nile Red within the nanotransporter shells that depends on solvent and temperature. In particular, we show that the flexibility of the polymer branches in the unimolecular state of the nanotransporter undergoes a temperature-dependent transition which correlates with a larger space for the mobility of the incorporated hydrophobic drug mimetic Nile Red and a higher probability of cargo-solvent interactions at temperatures above 31 °C. The measurements have further revealed that a loss of the cargo molecule Nile Red occurred neither upon dilution of the CMS nanotransporters nor upon heating. Thus, the unimolecular preloaded CMS nanotransporters retain their cargo and are capable to transport and respond to temperature, thereby fulfilling important requirements for biomedical applications.

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Section: Resultssupporting

confidence: 70%

Nanodynamics of Dendritic Core–Multishell Nanocarriers

et al. 2014

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“…The fluorescence quantum yield for NR in alcohols is diminished relative to nonpolar solvents, and the shift in emission maximum follows a different relationship with dielectric constant than is seen with polar aprotic solvents. 10 Because PVDF is polar and aprotic, we expect the NR emission to be dominated by LE state emission such that Figure 2 is interpreted as reflecting NR emission from different dielectric environments. Previous evidence for NR existing in different dielectric environments was found in studies of NR dual emission in polystyrene films.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Nile red (NR) has been widely used for this purpose, with the solvatochromic properties of this dye illustrated in Figure . The emission from NR exhibits a ∼100 nm bathochromic shift with a change in ε from ∼2 to ∼32. − The figure demonstrates that changes in the NR emission line shape are also observed between nonpolar (cyclohexane, heptane, and hexane) and polar solvents. These changes have been attributed to specific solvent interactions such as dipole–dipole, which increase the homogeneous line width. , NR has previously been used to measure the evolution in ε for poly(vinylidene fluoride) (PVDF) films accompanying the transition from disordered α phase to ferroelectric β phase upon stretching .…”

Section: Introductionmentioning

confidence: 88%

“…The emission from NR exhibits a ~100 nm bathochromic shift with a change in ε from ~2 to ~32. 7–10 The figure demonstrates that changes in the NR emission line shape are also observed between non-polar (cyclohexane, heptane and hexane) and polar solvents. These changes have been attributed to specific solvent interactions such as hydrogen bonding which increase the homogeneous line width.…”

Section: Introductionmentioning

confidence: 93%

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Measuring the Spatial Distribution of Dielectric Constants in Polymers through Quasi-Single Molecule Microscopy

et al. 2013

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The variation in dielectric constant is measured for thin films of poly(methyl methacrylate) (PMMA) and poly(vinylidene fluoride) (PVDF) using confocal fluorescence microscopy. Spatial variation in the local dielectric constant of the polymer films on the ~250 nm length scale is measured using the solvochromatic emission from incorporated nile red (NR) at “quasi-single molecule” (10−7 M) and true single molecule (SM) concentrations (10−9 M). Correlation of the NR fluorescence wavelength maximum with dielectric constant is used to transform images of NR’s emission maxima to spatial variation in local dielectric constant. We demonstrate that the distributions of dielectric environments measured in the quasi- and true SM approaches are equivalent; however, the enhanced signal rates present in the quasi-SM approach results in this technique being more efficient. In addition, the quasi-SM technique reports directly on the continuous spatial variation in dielectric constant, information that is difficult to obtain in true SM studies. With regards to the polymers of interest, the results presented here demonstrate that a limited distribution of dielectric environments is present in PMMA; however, a broad distribution of environments exists in PVDF consistent with this polymer existing as a distribution of structural phases.

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“…50 Nile red is known to undergo a blue shift of the maximum of emission as the polarity of the surrounding (micro)environment decreases. 48,57,58 For example, Rimmer and co-workers utilised Nile red as a polarity-sensitive probe to show that specific highly-branched poly(N-isopropyl acrylamide)s possessed core-shell morphologies. 59 In our experiments we observed a shift from ∼650 nm, close to that of Nile red in water, at the lowest [ polymer] : [dye] ratios (0.020 and 0.084 for linear (1) MAN and star (2) MAN , respectively), to 632-634 nm, starting from [polymer] : [dye] ∼0.5-1 (Fig.…”

Section: Resultsmentioning

confidence: 99%