TY - JOUR
T1 - Sol-gel entrapped light harvesting antennas
T2 - Immobilization and stabilization of chlorosomes for energy harvesting
AU - O'Dell, William B.
AU - Beatty, Kayla J.
AU - Kuo-Hsiang Tang, Joseph
AU - Blankenship, Robert E.
AU - Urban, Volker S.
AU - O'Neill, Hugh
PY - 2012/11/14
Y1 - 2012/11/14
N2 - The chlorosome is a highly specialized supramolecular light-harvesting antenna complex found in green photosynthetic bacteria and is composed of self-assembled bacteriochlorophyll (BChl) pigments entrapped in a lipid vesicle. These organelles are of interest for development of synthetic devices for solar harvesting and conversion because the organization and packing of BChls in the chlorosome provides a highly efficient light collection and energy funneling mechanism with properties that are superior to similar artificial systems based on self-assembled BChl pigment analogues. In this study, we investigated sol-gel chemistry as an approach to entrap and stabilize chlorosomes isolated from Chloroflexus aurantiacus. Two distinct synthesis approaches that differed in the H 2O/Si ratio in the gels were investigated. Spectrophotometric analysis showed that the chlorosomes were intact when encapsulated in sol-gels and did not suffer any deleterious effects during the entrapment process. In addition, the integrity of the chlorosomes was unaffected by methanol levels that can result during the formation of sol-gels. Using small-angle neutron scattering it was not only possible to characterize the properties of the sol-gel matrix but also the size, shape and aggregation state of the entrapped chlorosomes. The sol-gels formed at a higher H 2O/Si ratio (FH gels) resulted in a more branched gel structure with a larger pore size compared to the gels formed at lower H 2O/Si ratio (PH gels). The chlorosomes entrapped in FH gels had dimensions of ∼16.0 × 51.1 × 180.1 nm which agrees well with the size of chlorosomes previously determined using cryo-transmission electron microscopy, while the chlorosomes in the PH gels appear to be aggregated. The approach described here offers new possibilities for the development of artificial solar-harvesting and energy conversion devices based on naturally occurring photosynthetic systems.
AB - The chlorosome is a highly specialized supramolecular light-harvesting antenna complex found in green photosynthetic bacteria and is composed of self-assembled bacteriochlorophyll (BChl) pigments entrapped in a lipid vesicle. These organelles are of interest for development of synthetic devices for solar harvesting and conversion because the organization and packing of BChls in the chlorosome provides a highly efficient light collection and energy funneling mechanism with properties that are superior to similar artificial systems based on self-assembled BChl pigment analogues. In this study, we investigated sol-gel chemistry as an approach to entrap and stabilize chlorosomes isolated from Chloroflexus aurantiacus. Two distinct synthesis approaches that differed in the H 2O/Si ratio in the gels were investigated. Spectrophotometric analysis showed that the chlorosomes were intact when encapsulated in sol-gels and did not suffer any deleterious effects during the entrapment process. In addition, the integrity of the chlorosomes was unaffected by methanol levels that can result during the formation of sol-gels. Using small-angle neutron scattering it was not only possible to characterize the properties of the sol-gel matrix but also the size, shape and aggregation state of the entrapped chlorosomes. The sol-gels formed at a higher H 2O/Si ratio (FH gels) resulted in a more branched gel structure with a larger pore size compared to the gels formed at lower H 2O/Si ratio (PH gels). The chlorosomes entrapped in FH gels had dimensions of ∼16.0 × 51.1 × 180.1 nm which agrees well with the size of chlorosomes previously determined using cryo-transmission electron microscopy, while the chlorosomes in the PH gels appear to be aggregated. The approach described here offers new possibilities for the development of artificial solar-harvesting and energy conversion devices based on naturally occurring photosynthetic systems.
UR - http://www.scopus.com/inward/record.url?scp=84867338446&partnerID=8YFLogxK
U2 - 10.1039/c2jm34357f
DO - 10.1039/c2jm34357f
M3 - Article
AN - SCOPUS:84867338446
SN - 0959-9428
VL - 22
SP - 22582
EP - 22591
JO - Journal of Materials Chemistry
JF - Journal of Materials Chemistry
IS - 42
ER -