Plasmonic Bowl-Shaped Nanopore for Raman Detection of Single DNA Molecules in Flow-Through.

Plasmonic nanopores combined with Raman spectroscopy are emerging as platforms for single-molecule detection and sequencing in label-free mode. Recently, the ability of identifying single DNA bases or amino acids has been demonstrated for molecules adsorbed on plasmonic particles and then delivered into the plasmonic pores. Here, we report on bowl-shaped plasmonic gold nanopores capable of direct Raman detection of single λ-DNA molecules in a flow-through scheme. The bowl shape enables the incident laser to be focused into the nanopore to generate a single intense hot spot with no cut off in pore size. Therefore, we achieved ultrasmall focusing of NIR light in a spot of 3 nm. This enabled us to detect 7 consecutive bases along the DNA chain in flow-through conditions. Furthermore, we found a novel electrofluidic mechanism to manipulate the molecular trajectory within the pore volume so that the molecule is pushed toward the hot spot, thus improving the detection efficiency.

Organotin Selenide Clusters and Hybrid Capsules.

Several compounds with unique structural motifs that have already been known from organotin sulfide chemistry, but remained unprecedented in organotin selenide chemistry so far, have been synthesized. The reaction of [(R1 Sn)4 Se6 ] (R1 =CMe2 CH2 C(O)Me) with N2 H4 ⋅H2 O/(SiMe3 )2 Se and PhN2 H3 /(SiMe3 )2 Se led to the formation of [{(R2 Sn)2 SnSe4 }2 (µ-Se)2 ] (1; R2 =CMe2 CH2 C(Me)NNH2 ) and [{(R3 Sn)2 SnSe4 }2 (µ-Se)2 ] (2; R3 =CMe2 CH2 C(Me)NNPhH)). The addition of ortho-phthalaldehyde to [(R2 Sn)4 Se6 ] yielded a cluster with intramolecular bridging of the organic groups, namely, [(R4 Sn2 )2 Se6 ] (3; R4 =(CMe2 CH2 C(Me)NNCH)2 C6 H4 ). The introduction of organic ligands with longer chains finally allowed the isolation of inorganic-organic capsules of the type [(µ-R)3 (Sn3 Se4 )2 ]X2 , with R=(CMe2 CH2 C(Me)NNHC(O))2 (CH2 )4 and X=[SnC3 ], Cl (4 a, b) or R=CMe2 CH2 C(Me)NNH)2 and X=[SnCl3 ] (5). The capsules enclose solvent molecules and/or anions as guests. All compounds were characterized by means of single-crystal X-ray diffraction studies, NMR spectroscopy, and mass spectrometry.