Abstract
In this paper, a fine gold nanostructure synthesized on selective planar microelectrodes in micro-chip is realized by using an advanced hybrid fabrication approach incorporating growth of nanorods (NRs) with gold electroplating. By this developed nanostructure, integration of in-situ surface-enhanced Raman spectroscopy (SERS) detection with electrochemical impedance spectroscopy (EIS) measurement for label-free, nondestructive, real-time and rapid monitoring on a single cell has been achieved. Moreover, parameters of Au nanostructures such as size of nanoholes/nanogaps can be controllably adjusted in the fabrication. We have demonstrated a SERS enhancement factor of up to ~2.24 × 106 and double-layer impedance decrease ratio of 90% ~ 95% at low frequency range below 200 kHz by using nanostructured microelectrodes. SERS detection and in-situ EIS measurement of a trapped single cell by using planar microelectrodes are realized to demonstrate the compatibility, multi-functions, high-sensitivity and simplicity of the micro-chip system. This dual function platform integrating SERS and EIS is of great significance in biological, biochemical and biomedical applications.
Highlights
Surface-enhanced Raman spectroscopy (SERS) detection and electrochemical impedance spectroscopy (EIS) measurement have attracted great attention due to their promising advantages of rapid diagnosis, nondestructive and easy handling in analytical chemistry, characterization of trace chemical species, life science, and medical science[1,2,3,4]
Compared with other template materials such as silicon or PS18000-b-PEO7500 micelle[20,21], Zinc oxide (ZnO) nanorods are synthesized because they can be controllably grown on selected electrodes by using an electric-field assisted hydrothermal method at a gentle temperature which is compatible with pre-fabricated micro-chip[22]
The dissolution of ZnO NRs and the formation of Au nanostructure occur at the same time, and ZnO template can be completely removed in the process of electroplating without further treatment
Summary
Surface-enhanced Raman spectroscopy (SERS) detection and electrochemical impedance spectroscopy (EIS) measurement have attracted great attention due to their promising advantages of rapid diagnosis, nondestructive and easy handling in analytical chemistry, characterization of trace chemical species, life science, and medical science[1,2,3,4]. These methods have synthesized nanostructures on substrate with high scattering enhancement factor, most of them are not compatible with pre-fabricated micro-chip. It is a great challenge to fabricate nanostructures selectively on target microelectrodes performing SERS detection and in-situ impedance measurement. We propose a hybrid fabrication approach by incorporating growth of nanorods (NRs) with gold electroplating process, which can selectively construct fine gold nanostructure on target microelectrode for SERS detection and EIS measurement. Compared with other template materials such as silicon or PS18000-b-PEO7500 micelle[20,21], Zinc oxide (ZnO) nanorods are synthesized because they can be controllably grown on selected electrodes by using an electric-field assisted hydrothermal method at a gentle temperature which is compatible with pre-fabricated micro-chip[22]. The dissolution of ZnO NRs and the formation of Au nanostructure occur at the same time, and ZnO template can be completely removed in the process of electroplating without further treatment
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