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Published on: November 13, 2006
Light-induced morphological transition between unconjugated bilirubin photoisomers
Siddhartha Pal1, Pavel Banerjee1, Dipankar Mondal1
1Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, West Bengal, India. nilmoni@chem.iitkgp.ac.in.
Abstract:
Morphology switching by an external stimulus creates the possibility to detect and control the activity and functionality of bio-molecules. Unconjugated bilirubin (UCB), a waste product resulting from heme catabolism, is highly sensitive towards blue light induced configurational conversion from (4Z,15Z) to (4Z,15E)-bilirubin. UCB has a distinct elongated nanostructure which is readily photoswitchable to spherical by external blue light (470 nm) irradiation. Herein, the morphology alteration by blue light was nicely correlated with the photoisomerisation of UCB, using different microscopic and spectroscopic techniques. To restrict the other photo-incidents during phototreatment on UCB, a suitable time frame was calibrated by monitoring the absorption, HPLC, lifetime distribution and 1H NMR studies. Furthermore, by the help of this morphological transition as a marker, UCB early stage photoisomerisation has also been triggered by two-photon irradiation (940 nm).
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