Size-Controllable Gold Nanopores with High SERS Activity

Abstract

Nanopore structures have been successfully employed in next-generation DNA sequencing. For more complicated protein which normally contains 20 different amino acids, identifying the fluctuation of ionic current caused by different amino acids appears inadequate for protein sequencing. Therefore, it is highly desirable to develop size-controllable nanopores with optical activity that can provide additional structural information. Herein, we discovered the novel nanopore properties of the self-assembled ultramicroelectrodes originally developed by Bard and co-workers. Using a slightly modified method, the self-assembly of 7 ± 1 nm gold nanoparticles (AuNPs) can be precisely controlled to form a gold nanoporous sphere (GPS) on the tip of a glass capillary. Different dithiol linker molecules (1,3-propanedithiol, C3; 1,6-hexanedithiol, C6; and 1,9-nonanedithiol, C9) reproducibly led to rather similar nanopore sizes (5.07 ± 0.02, 5.13 ± 0.02, and 5.25 ± 0.01 nm), respectively. The GPS nanostructures were found to exhibit high ionic current rectification as well as surface-enhanced Raman scattering (SERS) activity due to the presence of nanopores and numerous "hot spots" among the cross-linked AuNPs on the surface of GPS. The rectification effect of the small nanopores was observed even under high concentration of electrolyte (290 mM), along with SERS enhancement factors well above 1 × 10. The GPS nanostructures were successfully applied for SERS-based detection of glutathione from a single HeLa cell.

Axial ligands tailoring the ORR activity of cobalt porphyrin

“…The intense peak at 2,232 cm À1 belongs to the stretching mode of the ACN group [35]. This peak position is very close to that of neat state, which indicates that molecule adsorption with ACN group is unlikely, since the interaction of ACN with metal substrate would induce significant peak position shift of the ACN stretching mode [36]. In the SERS spectrum of APT molecule (red curve), the several intense b 2 -type bands in the region between 1,100 and 1,500 cm À1 are the characteristics of the ANH 2 derivatives and provide direct evidence of APT adsorption on the surface with the ANH 2 ligand group unperturbed [37].…”

Green Synthesis of Gold Nanoparticles using Pimenta dioica Leaves Aqueous Extract and Their Application as Photocatalyst, Antioxidant, and Antibacterial Agents

“…Form, size, crystallinity, and structure are all important factors in these applications. Gold nanostructures have been identified in a variety of shapes, including nanocubes [11], nanowires [12], nanoplates [13], nanospheres, nanorods [14], nanopores [15], nanobelts, and odd angled shapes [16]. Many groups of researchers have long been interested in one-dimensional (1D) metallic nanostructures.…”

Mesoporous Carbon Structure-Based Glass Nanopipettes as Micro pH Probes

“…[1][2][3][4][5] Solid-state nanopores have been of considerable fundamental interest, including DNA sequencing, protein detection, molecule/ion sensors, nanofluidics, high-efficiency energy storage and conversion systems, due to the tunable pore size and stable physical/chemical properties. [6][7][8][9][10][11] To improve the selectivity and sensitivity of nanopore-based sensors and to add new functionality to nanopore devices, it is desirable to chemically modify their inner surfaces by covalent attachment of specific molecules. [12][13][14] Smart nanopore sensors responding to the temperature, potential, pH and light were fabricated by modifying the interior surface with suitable stimuli-response materials.…”