Abstract
We experimentally demonstrate the simultaneous enhancement of Raman and photoluminescence (PL) of core-shell hybrid nanoparticles consisting of Ag (core) and polydiacetylene (PDA, shell) through the assistance of localized surface plasmon (LSP) effect for the effective biosensor. Core-shell nanoparticles (NPs) are fabricated in deionized water through a sequential process of reprecipitation and self-assembly. The Raman signal of PDA on core-shell NPs is enhanced more than 100 times. Also, highly enhanced photoluminescence is observed on Ag/PDA hybrid NPs after coupling of the complementary t-DNA with p-DNA which are immobilized on PDA shell. This indicates that the core Ag affects the Raman and PL of PDA through the LSP resonance, which can be caused by the energy and/or charge transfer caused by the LSP coupling and the strong electromagnetic field near Ag NP surface. Only electrons present on the surface interact with the PDA shell, not involving the electrically neutral part of the electrons inside the Ag NP. Furthermore, this work shows that as prepared Ag/PDA NPs functionalized by probe DNA can sense the target DNA with an attomolar concentration (100 attomole).
Highlights
With the rapid development of optical spectroscopy instruments with high spatial resolution beyond the diffraction limit, the optical properties of individual nano-architectures have been successfully measured and analyzed [1,2,3]
This localized surface plasmon (LSP) resonant interaction with exciton occurring on the organic-metal hybrid system is believed to be due to the interaction of excited and delocalized electrons from organic materials, which are located between the interface of hybrid materials, with an enforced electromagnetic (EM)
Ag NPs, and the as-prepared Ag NPs were coated by DA nano-shell (NS) as the carboxyl acid end-groups favor anchoring onto the surface of Ag NP
Summary
With the rapid development of optical spectroscopy instruments with high spatial resolution beyond the diffraction limit, the optical properties of individual nano-architectures have been successfully measured and analyzed [1,2,3]. When the plasmon frequency of metal materials is resonated with the exciton of the organic materials in the hybrid nanostructure, the non-linearly enhanced photoluminescence or Raman signal can be observed even from single molecules [16,17,18,19,20,21,22]. This LSP resonant interaction with exciton occurring on the organic-metal hybrid system is believed to be due to the interaction of excited and delocalized electrons from organic materials, which are located between the interface of hybrid materials, with an enforced electromagnetic (EM)
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