Abstract
ABSTRACTEumelanosomes and pheomelanosomes isolated from black and red human hair, respectively, were studied by photo‐electron emission microscopy (PEEM). PEEM images were collected at various wavelengths between 207 and 344 nm, using the spontaneous emission output of the Duke OK‐4 free electron laser (FEL). Analysis of the FEL‐PEEM data revealed ionization thresholds of 4.6 and 3.9 eV corresponding to oxidation potentials of −0.2 and +0.5 V vs normal hydrogen electrode for eumelanosomes and pheomelanosomes, respectively. The difference in oxidation potential is attributed to the pigment content of the melanosome, namely whether it contains primarily eumelanin and pheomelanin. The effect of added melanosomes on the reduction of Fe(III)‐cytochrome showed pheomelanosomes are stronger reducing agents than eumelanosomes, consistent with the measured oxidation potentials. The FEL‐PEEM experiment offers to be an important new approach for quantifying the effects of age, oxidation and metal accumulation on the oxidation potentials of intact melanosomes.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
