In situ laser-induced photochemical silver substrate synthesis and sequential SERS detection in a flow cell

Herman, Krisztian; Szabó, László; Leopold, Loredana; Chiş, Vasile; Leopold, Nicolae

doi:10.1007/s00216-011-4798-5

Cited by 20 publications

(14 citation statements)

References 24 publications

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“…Thus, the SERS bands of citrate previously reported by us [31–32] during the laser induced synthesis of SERS-active silver spots using silver nitrate-citrate mixtures can easily be explained by the presence of excess of Ag + in the solution, which induces the chemisorption of citrate onto the metal silver surface.…”

Section: Resultsmentioning

confidence: 71%

The role of adatoms in chloride-activated colloidal silver nanoparticles for surface-enhanced Raman scattering enhancement

Leopold

Ştefancu

Herman

et al. 2018

Beilstein J. Nanotechnol.

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Chloride-capped silver nanoparticles (Cl-AgNPs) allow for high-intensity surface-enhanced Raman scattering (SERS) spectra of cationic molecules to be obtained (even at nanomolar concentration) and may also play a key role in understanding some fundamental principles behind SERS. In this study, we describe a fast (<10 min) and simple protocol for obtaining highly SERS-active colloidal silver nanoparticles (AgNPs) with a mean diameter of 36 nm by photoconversion from AgCl precursor microparticles in the absence of any organic reducing or capping agent. The resulting AgNPs are already SERS-activated by the Cl− ions chemisorbed onto the metal surface where the chloride concentration in the colloidal solution is 10−2 M. Consequently, the enhanced SERS spectra of cationic dyes (e.g., crystal violet or 9-aminoacridine) demonstrate the advantages of Cl-AgNPs compared to the as-synthesized AgNPs obtained by standard Ag+ reduction with hydroxylamine (hya-AgNPS) or citrate (cit-AgNPs). The results of SERS experiments on anionic and cationic test molecules comparing Cl-AgNPs, hya-AgNPs and cit-AgNPs colloids activated with different amounts of Cl− and/or cations such as Ag+, Mg2+ or Ca2+ can be explained within the understanding of the adatom model – the chemisorption of cationic analytes onto the metal surface is mediated by the Cl− ions, whereas ions like Ag+, Mg2+ or Ca2+ mediate the electronic coupling of anionic species to the silver metal surface. Moreover, the SERS effect is switched on only after the electronic coupling of the adsorbate to the silver surface at SERS-active sites. The experiments presented in this study highlight the SERS-activating role played by ions such as Cl−, Ag+, Mg2+ or Ca2+, which is a process that seems to prevail over the Raman enhancement due to nanoparticle aggregation.

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Section: Resultsmentioning

confidence: 71%

The role of adatoms in chloride-activated colloidal silver nanoparticles for surface-enhanced Raman scattering enhancement

Leopold

Ştefancu

Herman

et al. 2018

Beilstein J. Nanotechnol.

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“…The silver substrate was situated on an integrated ITO electrode and after the sample introduction a 100 V potential pulse was applied resulting in a significant decrease of the memory effect. The recovery of the SERS substrate could be also reached within a few minutes in flow conditions on silver spots created by in situ photo‐induced reduction of NPs precursors . The small surface area resulted in relatively fast adsorption and desorption (typically several minutes) of the analyte molecules to/from the silver surface and represents promising approach toward SERS coupling with liquid‐based separation methods.…”

Section: In‐solution Strategymentioning

confidence: 99%

Recent strategies toward microfluidic‐based surface‐enhanced Raman spectroscopy

2017

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Surface-enhanced Raman spectroscopy (SERS) is an extremely powerful analytical tool, which not only yields information about the molecular structure of the analyte in the form of characteristic vibrational spectrum but also gives sensitivities approaching those in fluorescence spectroscopy. The SERS measurement on the microfluidic platform provides possibility to manufacture the device with design perfectly fulfilling the needs of the application with minimal sample consumption. This review aims at describing basic strategies for SERS measurement in microfluidic devices published in the last decade and covers current trends in microfluidics with SERS detection in the field of bioanalysis and approaches toward on-line coupling of liquid-based separation techniques with SERS detection.

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“…One is the in-situ fabrication of SERS-active metallic micro/nanostructures inside a microfl uidic channel, and the other is the construction of microfl uidic channels on top of the SERS substrates. [103][104][105][106] The femtosecond laser direct writing (FsLDW) technique is recognized as a powerful nanofabrication tool that could fabricate 3D complex nanostructures on a wide range of materials. Takahashi et al reported the integration of a 3D Au photonic crystal (PC) structure through the co-assembly of Au colloidal nanoparticles and large PS nanospheres inside a microfl uidic channel.…”

Section: Integration Of Solid-state Sers Substrates With Microfl Uidimentioning

confidence: 99%

SERS‐Enabled Lab‐on‐a‐Chip Systems

Huang

Zhang

Ding

et al. 2015

Advanced Optical Materials

104

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REVIEWnanoparticle array with fi xed nanogaps on solid-state substrates. [ 8 ] Cross-contamination and channel clogging could be avoided in microfl uidic chips equipped with solid-state SERS substrates that will not fl ow with analytes. [ 15 ] On this basis, implanting solid-state SERS substrates within microfl uidic devices could enable SERS-independent functions in SERSenabled LoC systems, such as microfl uidic chemical reactors. [ 16 ] On the other hand, LoC systems could serve as an integrated platform to make SERS detection more reproducible, effi cient, safe, and environmentally friendly. For example, recent microfl uidic reversible manipulations have allowed controllable colloid aggregation in microfl uidic channels. [ 17 ] More importantly, dynamic molecule trapping in microfl uidic devices could address the uneven distribution of analytes (e.g., the coffeering effect) on solid-state SERS substrates. [ 18 ] Furthermore, the fl exible integration of SERS substrates with microfl uidic chips would contribute to the commercialization of portable SERS chips.The combination of microfl uidics with SERS not only provides new opportunities for both techniques as outlined above, but also paves the way for multifunctional SERS-enabled LoC systems beyond SERS detection, which is often overlooked by both communities. In this review, we will bridge this gap by discussing the recent advancements in both SERS-enabled LoC systems and reproducible SERS substrates, as well as their complementary combination. For a better understanding of the fundamental role of SERS substrates in SERS-enabled LoC systems, the fundamentals of SERS will be briefl y described in Section 2. Section 3 will discuss technical progress with respect to the fabrication of multifunctional SERS-enabled microfl uidic devices, including reproducible SERS substrates and microfl uidic dynamic trapping methods. Applications of SERS-enabled LoC systems in chemical and biological detection, as well as the commercial perspective of portable SERS devices, will be discussed in Section 4. Finally, in Section 5, we will conclude with current challenges and offer an outlook on multifunctional SERS-enabled LoC systems.

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In situ laser-induced photochemical silver substrate synthesis and sequential SERS detection in a flow cell

Cited by 20 publications

References 24 publications

The role of adatoms in chloride-activated colloidal silver nanoparticles for surface-enhanced Raman scattering enhancement

The role of adatoms in chloride-activated colloidal silver nanoparticles for surface-enhanced Raman scattering enhancement

Recent strategies toward microfluidic‐based surface‐enhanced Raman spectroscopy

SERS‐Enabled Lab‐on‐a‐Chip Systems

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