Radiative Relaxation Quantum Yields for Synthetic Eumelanin ¶

  title={Radiative Relaxation Quantum Yields for Synthetic Eumelanin ¶},
  author={Paul Meredith and Jenny Riesz},
  journal={Photochemistry and Photobiology},
We report absolute values for the radiative relaxation quantum yield of synthetic eumelanin as a function of excitation energy. These values were determined by correcting for pump beam attenuation and emission reabsorption in both eumelanin samples and fluorescein standards over a large range of concentrations. Our results confirm that eumelanins are capable of dissipating >99.9% of absorbed UV and visible radiation through nonradiative means. Furthermore, we have found that the radiative… Expand
14 Citations
Understanding the Role of Aggregation in the Broad Absorption Bands of Eumelanin.
It is shown that the geometric packing order of protomolecules in long-range aggregation is key secondary interactions to extend the absorption band of eumelanin to the low energy spectrum and produce drastic changes in the transient absorption spectrum. Expand
Infrared spectroscopy of hydration-controlled eumelanin films suggests the presence of the Zundel cation
Eumelanin is a widespread biomacromolecule pigment in the biosphere and is intensively tested in numerous bioelectronics and energetic applications. Many of these applications depend on eumelanin’sExpand
Size-Dependent Local Ordering in Melanin Aggregates and Its Implication on Optical Properties.
The analysis reveals the formation of secondary structures due to π-stacking on one hand, but on the other a broad distribution of stack geometries in terms of stack size, horizontal displacement angles, and relative torsion angles that support the geometric disorder model, which complements the chemical disorder model in the interpretation of eumelanin's monotonically increasing broad band absorption. Expand
Understanding the way eumelanin works: A unique example of properties and skills driven by molecular heterogeneity
The focus is on the state-of-art, on the translation of major concepts into novel applications, and on the main remaining challenges for the use of a biomaterial characterized by unusual precious characteristics. Expand
Whole-Cell Photoacoustic Sensor Based on Pigment Relocalization
A photoac acoustic pigment relocalization sensor (PaPiReS) is introduced for molecular photoacoustic imaging of GPCR-mediated signaling molecules of cuttlefish who can change their color by relocalizing pigment-filled organelles in so-called chromatophore cells under neurohumoral control. Expand
Melanin biopolymers: tailoring chemical complexity for materials design.
The various levels of structural disorder that emerged from spectral and chemical signatures over the past decade are brought to focus and a revised entry to structure-property relationships in terms of intermolecular interactions is provided that may track the path toward the rational design of next generation melanin-based functional materials. Expand
Novel amide derivatives as potent tyrosinase inhibitors; in-vitro, in-vivo antimelanogenic activity and computational studies.
Compound 5c is proposed as a potential candidate to control tyrosinase rooted hyperpigmentation in the future and demonstrates that 5c interact with copper ions and multiple amino acids in the active site of tyosinase with best glide score (-5.387 kcal/mol). Expand
Forensic determination of hair deposition time in crime scenes using electron paramagnetic resonance
This study provides a reference for future forensic studies on determination of degradation of shed hair in a crime scene by following eumelanin radicals by utilizing the non‐invasive, non‐destructive, and highly specific EPR technique. Expand
Skin colour and vitamin D: An update
It is demonstrated that skin lightening happened as late as 5000 years ago through immigration of lighter pigmented populations from western Anatolia and the Russian steppe but not primarily via evolutionary pressure for vitamin D3 synthesis. Expand
Properties of melanin from Lachnum YM156 and its hepatoprotective effect in Cd-exposure mice
Abstract Natural melanin was extracted from Lachnum YM156 (LIM). LIM had better thermostability and light resistance, and its solubility was relatively high under alkaline conditions. Simultaneously,Expand


Radiative Relaxation of Sepia Eumelanin is Affected by Aggregation ¶
The steady‐state and time‐resolved emission properties of aqueous solutions containing different aggregation state distributions of eumelanin are reported. Excitation spectra of the size‐selectedExpand
Explanation for the Disparity among Absorption and Action Spectra of Eumelanin
The optical properties of eumelanin (from Sepia officinalis) are found to vary with particle size. The absorption spectrum for small eumelanin particles agrees quantitatively with the reported actionExpand
Ultrafast Nonradiative Relaxation Dynamics of Eumelanin
Degenerate pump−probe femtosecond spectroscopy is used to examine the primary photodynamics of eumelanin from Sepia officinalis following UV-A excitation. Exciting and probing at 320, 350, and 380 nmExpand
Abstract— An introduction to the fundamental characteristics of synthetic melanin fluorescence is presented. The particular difficulties associated with the detection and reduction of the relativelyExpand
Fluorescence properties of melanins from opioid peptides.
These findings suggest that the observed fluorescence contains contributions from both oligomeric units and high-molecular-weight polymers (520-nm band), which is in contrast to previous reports. Expand
Fluorescence spectroscopy of eumelanins
The fluorescence spectra from different forms of melanin, excited by an argon-ion laser at 488 nm wavelength were measured. The fluorescence intensity and maxima were found to be dependent on theExpand
A band model for melanin deducted from optical absorption and photoconductivity experiments.
Natural and synthetic melanins have been studied by optical absorption and photoconductivity measurements in the range 200--700 nm, and a negative photoc conductivity was observed with a maximum near 500 nm. Expand
Effect of Cu(2+)-ions on semiconductor properties of synthetic DOPA melanin polymer.
Data suggest, that DOPA melanin polymer could be useful as a type of culture substratum, which are basic for future biological applications. Expand
The fundamental unit of synthetic melanin: a verification by tunneling microscopy of X-ray scattering results.
Identification of a melanin protomolecule of approximately approximately 20 A lateral extent and approximately 10 A height has been established, in good agreement with models constructed to fit wide angle X-ray diffraction experiments on melanin. Expand
Building Blocks of Eumelanin: Relative Stability and Excitation Energies of Tautomers of 5,6-Dihydroxyindole and 5,6-Indolequinone
Computation methods were used to examine the tautomerization equilibria for 5,6-dihydroxyindole (DHI, 2) and 5,6-indolequinone (IQ, 3). Relative energies were calculated at the B3LYP and PBE0 levelExpand