TY  - JOUR
A1  - Heck, Christian
A1  - Prinz, Julia
A1  - Dathe, Andre
A1  - Merk, Virginia
A1  - Stranik, Ondrej
A1  - Fritzsche, Wolfgang
A1  - Kneipp, Janina
A1  - Bald, Ilko
T1  - Gold Nanolenses Self-Assembled by DNA Origami
JF  - ACS Photonics
N2  - Nanolenses are self-similar chains of metal nanoparticles, which can theoretically provide extremely high field enhancements. Yet, the complex structure renders their synthesis challenging and has hampered closer analyses so far. Here, DNA origami is used to self-assemble 10, 20, and 60 nm gold nanoparticles as plasmonic gold nanolenses (AuNLs) in solution and in billions of copies. Three different geometrical arrangements are assembled, and for each of the three designs, surface-enhanced Raman scattering (SERS) capabilities of single AuNLs are assessed. For the design which shows the best properties, SERS signals from the two different internal gaps are compared by selectively placing probe dyes. The highest Raman enhancement is found for the gap between the small and medium nanoparticle, which is indicative of a cascaded field enhancement.
KW  - plasmonics
KW  - DNA origami
KW  - SERS
KW  - nanolenses
KW  - gold nanoparticles
Y1  - 2017
U6  - https://doi.org/10.1021/acsphotonics.6b00946
SN  - 2330-4022
VL  - 4
SP  - 1123
EP  - 1130
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Heck, Christian
A1  - Kanehira, Yuya
A1  - Kneipp, Janina
A1  - Bald, Ilko
T1  - Amorphous Carbon Generation as a Photocatalytic Reaction on DNA-Assembled Gold and Silver Nanostructures
JF  - Molecules
N2  - Background signals from in situ-formed amorphous carbon, despite not being fully understood, are known to be a common issue in few-molecule surface-enhanced Raman scattering (SERS). Here, discrete gold and silver nanoparticle aggregates assembled by DNA origami were used to study the conditions for the formation of amorphous carbon during SERS measurements. Gold and silver dimers were exposed to laser light of varied power densities and wavelengths. Amorphous carbon prevalently formed on silver aggregates and at high power densities. Time-resolved measurements enabled us to follow the formation of amorphous carbon. Silver nanolenses consisting of three differently-sized silver nanoparticles were used to follow the generation of amorphous carbon at the single-nanostructure level. This allowed observation of the many sharp peaks that constitute the broad amorphous carbon signal found in ensemble measurements. In conclusion, we highlight strategies to prevent amorphous carbon formation, especially for DNA-assembled SERS substrates.
KW  - amorphous carbon
KW  - DNA origami
KW  - SERS
KW  - nanoparticle dimers
KW  - nanolenses
Y1  - 2019
U6  - https://doi.org/10.3390/molecules24122324
SN  - 1420-3049
VL  - 24
IS  - 12
PB  - MDPI
CY  - Basel
ER  -