PMID- 23002723
OWN - NLM
STAT- MEDLINE
DCOM- 20131115
LR  - 20130304
IS  - 1751-1097 (Electronic)
IS  - 0031-8655 (Linking)
VI  - 89
IP  - 2
DP  - 2013 Mar-Apr
TI  - Intermolecular pi-electron perturbations generate extrinsic visible contributions 
      to eumelanin black chromophore in model polymers with interrupted interring 
      conjugation.
PG  - 314-8
LID - 10.1111/php.12003 [doi]
AB  - The key structural factors underlying the unique black chromophore of eumelanin 
      biopolymers have so far defied elucidation. Capitalizing on the ability of 1% 
      polyvinylalcohol (PVA) to prevent pigment precipitation during melanogenesis in 
      vitro, we have investigated the visible chromophore properties of soluble 
      eumelanin-like polymers produced by biomimetic oxidation of 5,6-dihydroxyindole 
      (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA) in 1% PVA-containing 
      buffer at pH 7. Upon dilution DHI-eumelanin solutions exhibited almost linear 
      visible absorbance changes, whereas DHICA-eumelanin displayed a remarkable 
      deviation from linearity in simple buffer, but not in PVA-containing buffer. It 
      is suggested that in DHICA polymers, exhibiting repeated interruptions of 
      interring conjugation due to lack of planar conformations, the black chromophore 
      is not due to an overlap of static entities defined intrinsically by the 
      conjugation length across the carbon frame, but results largely from 
      aggregation-related intermolecular perturbations of the pi-electron systems which 
      are extrinsic in character.
CI  - (c) 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology (c) 2012 The 
      American Society of Photobiology.
FAU - Ascione, Laura
AU  - Ascione L
AD  - Department of Chemical Sciences, University of Naples Federico II, Naples, Italy.
FAU - Pezzella, Alessandro
AU  - Pezzella A
FAU - Ambrogi, Veronica
AU  - Ambrogi V
FAU - Carfagna, Cosimo
AU  - Carfagna C
FAU - d'Ischia, Marco
AU  - d'Ischia M
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20121102
PL  - United States
TA  - Photochem Photobiol
JT  - Photochemistry and photobiology
JID - 0376425
RN  - 0 (Biopolymers)
RN  - 0 (Indoles)
RN  - 0 (Melanins)
RN  - 12627-86-0 (eumelanin)
RN  - 4790-08-3 (5,6-dihydroxy-2-indolylcarboxylic acid)
RN  - 9002-89-5 (Polyvinyl Alcohol)
RN  - Z3OC8499KG (5,6-dihydroxyindole)
SB  - IM
MH  - Biopolymers/*chemistry
MH  - *Electrons
MH  - Hydrogen-Ion Concentration
MH  - Indoles/*chemistry
MH  - Melanins/*chemistry
MH  - Oxidation-Reduction
MH  - Polyvinyl Alcohol/*chemistry
MH  - Ultraviolet Rays
EDAT- 2012/09/26 06:00
MHDA- 2013/11/16 06:00
CRDT- 2012/09/26 06:00
PHST- 2012/07/06 00:00 [received]
PHST- 2012/09/20 00:00 [accepted]
PHST- 2012/09/26 06:00 [entrez]
PHST- 2012/09/26 06:00 [pubmed]
PHST- 2013/11/16 06:00 [medline]
AID - 10.1111/php.12003 [doi]
PST - ppublish
SO  - Photochem Photobiol. 2013 Mar-Apr;89(2):314-8. doi: 10.1111/php.12003. Epub 2012 
      Nov 2.