A Facile Deposition of Silver onto the Inner Surface of a Glass Capillary Tube for Micro-Surface-Enhanced Raman Scattering Measurements

Abstract

Silver can be deposited very efficiently onto glass substrates using only ethanolic solutions of AgNO₃ and butylamine. This paper reports that the inner surface of a glass capillary can also be coated evenly with silver by shaking it after soaking in ethanolic solutions of AgNO₃ and butylamine; the silver deposited outside the capillary can be easily wiped off with cotton wool before drying. The grain size of the silver deposited onto the inner surface can be readily controlled within the range from 20 to 100 nm by varying the relative molar ratio of butylamine and AgNO₃ used as reactants. Due to its nanoaggregated structure, the Ag coated capillary is a very efficient surface-enhanced Raman scattering (SERS) active substrate, particularly usable in the microanalysis of chemicals; the detection limit of adenine is as low as 1.0 × 10⁻⁷ M based on a signal-to-noise (S/N) ratio of 3. Since the proposed method is cost-effective and is suitable for the mass production of Ag coated capillaries, we fully expect it to play a significant role in the development of SERS based microchip analyzers and even in the fabrication of Ag coated hollow glass waveguides.