@article{LiebigSarhanPrietzeletal.2018, author = {Liebig, Ferenc and Sarhan, Radwan Mohamed and Prietzel, Claudia Christina and Schmitt, Clemens Nikolaus Zeno and Bargheer, Matias and Koetz, Joachim}, title = {Tuned Surface-Enhanced raman scattering performance of undulated Au@Ag triangles}, series = {ACS applied nano materials}, volume = {1}, journal = {ACS applied nano materials}, number = {4}, publisher = {American Chemical Society}, address = {Washington}, issn = {2574-0970}, doi = {10.1021/acsanm.8b00570}, pages = {1995 -- 2003}, year = {2018}, abstract = {Negatively charged ultraflat gold nanotriangles (AuNTs) stabilized by the anionic surfactant dioctyl sodium sulfosuccinate (AOT) were reloaded with the cationic surfactant benzylhexadecyldimethylammonium chloride (BDAC). Because of the spontaneous formation of a catanionic AOT micelle/BDAC bilayer onto the surface of the reloaded AuNTs, a reduction of Ag+ ions leads to the formation of spherical silver nanoparticles (AgNPs). With increasing concentration of AgNPs on the AuNTs, the localized surface plasmon resonance (LSPR) is shifted stepwise from 1300 to 800 nm. The tunable LSPR enables to shift the extinction maximum to the wavelength of the excitation laser of the Raman microscope at 785 nm. Surface-enhanced Raman scattering (SERS) experiments performed under resonance conditions show an SERS enhancement factor of the analyte molecule rhodamine RG6 of 5.1 X 10(5), which can be related to the silver hot spots at the periphery of the undulated gold nanoplatelets.}, language = {en} } @article{HeckKanehiraKneippetal.2018, author = {Heck, Christian and Kanehira, Yuya and Kneipp, Janina and Bald, Ilko}, title = {Placement of Single Proteins within the SERS Hot Spots of Self-Assembled Silver Nanolenses}, series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, volume = {57}, journal = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, number = {25}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1433-7851}, doi = {10.1002/anie.201801748}, pages = {7444 -- 7447}, year = {2018}, abstract = {This study demonstrates the bottom-up synthesis of silver nanolenses. A robust coating protocol enabled the functionalization of differently sized silver nanoparticles with DNA single strands of orthogonal sequence. Coated particles 10nm, 20nm, and 60nm in diameter were self-assembled by DNA origami scaffolds to form silver nanolenses. Single molecules of the protein streptavidin were selectively placed in the gap of highest electric field enhancement. Streptavidin labelled with alkyne groups served as model analyte in surface-enhanced Raman scattering (SERS) experiments. By correlated Raman mapping and atomic force microscopy, SERS signals of the alkyne labels of a single streptavidin molecule, from a single silver nanolens, were detected. The discrete, self-similar aggregates of solid silver nanoparticles are promising for plasmonic applications.}, language = {en} } @article{BalderasValadezEstevezEspinozaSalazarKurietal.2018, author = {Balderas-Valadez, Ruth Fabiola and Estevez-Espinoza, J. O. and Salazar-Kuri, U. and Pacholski, Claudia and Mochan, Wolf Luis and Agarwal, Vivechana}, title = {Fabrication of ordered tubular porous silicon structures by colloidal lithography and metal assisted chemical etching}, series = {Applied surface science : a journal devoted to applied physics and chemistry of surfaces and interfaces}, volume = {462}, journal = {Applied surface science : a journal devoted to applied physics and chemistry of surfaces and interfaces}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0169-4332}, doi = {10.1016/j.apsusc.2018.08.120}, pages = {783 -- 790}, year = {2018}, abstract = {Fabrication of well-ordered porous silicon tubular structures using colloidal lithography and metal assisted chemical etching is reported. A continuous hexagonal hole/particle gold pattern was designed over monocrystalline silicon through deposition of polyNIPAM microspheres, followed by the surface decoration with gold nanoparticles and thermal treatment. An etching reaction with HF, ethanol and H2O2 dissolved the silicon in contact with the metal nanoparticles (NP), creating a porous tubular array in the "off-metal area". The morphological characterization revealed the formation of a cylindrical hollow porous tubular shape with external and internal diameter of approx. 900 nm and 400 nm respectively, though it can be tuned to other desired sizes by choosing an appropriate dimension for the microspheres. The porous morphology and optical properties were studied as a function of resistivity of silicon substrates. Compared to two different gold templates on cSi and nontubular porous pillar structures, porous silicon tubular framework revealed a maximum surface enhanced Raman scattering enhancement factor of 10(6) for the detection of 6-mercaptopurine (6-MP). Due to the large surface area available for any surface modification, open nanostructured platforms such as those studied here have potential applications in the field of reflection/photoluminescene and SERS based optical bio-/chemical sensors.}, language = {en} }