SERRS. In situ substrate formation and improved detection using microfluidics

R. Keir, E. Igata, M. Arundell, W.E. Smith, D. Graham, C. McHugh, J.M. Cooper

Research output: Contribution to journalArticle

67 Citations (Scopus)

Abstract

Surface-enhanced resonance Raman scattering (SERRS) of a model derivative of TNT was detected using a microflow cell designed within the framework of the lab-on-a-chip concept, using only the analyte and readily available reagents. The SERRS substrate, silver colloid, was prepared in situ, on-chip, by borohydride reduction of silver nitrate. The silver colloid was imaged within the chip using a white light microscope in either transmission or, due to the high reflectivity of the colloid, reflection mode. A fine stream of colloid similar to30 mum in width was formed in a 250-mum-wide channel at the point where the colloid preparation reagents met. The chip was designed to produce a concentrated stream of colloid within a laminar regime, such that particles did not readily disperse into the fluid. One result of this was to reduce the effective volume of analysis. Attempts to deliberately disrupt this stream with microstructured pillars, fabricated in the fluidic channels, were unsuccessful. The chip was also designed to have the appropriate dimensions for detection using a modern Raman microscope system, which collects scattering from a very small volume. A dye derived from TNT was used as a model analyte. Quantitative behavior was obtained over 4 orders of magnitude with a detection limit of 10 fmol. This performance is between 1 and 2 orders of magnitude better than that achieved using a macroflow SERRS cell. The technique has the added advantage that both reagent consumption and effluent production are greatly reduced, leading to reduced operating costs and a decreased environmental impact.
LanguageEnglish
Pages1503-1508
Number of pages5
JournalAnalytical Chemistry
Volume74
Issue number7
DOIs
Publication statusPublished - 1 Apr 2002

Fingerprint

Colloids
Microfluidics
Raman scattering
Trinitrotoluene
Substrates
Microscopes
Silver Nitrate
Borohydrides
Lab-on-a-chip
Wave transmission
Fluidics
Operating costs
Environmental impact
Effluents
Coloring Agents
Scattering
Derivatives
Fluids
colloidal silver

Keywords

  • surface-enhanced raman
  • flow-injection analysis
  • silver electrode
  • liquid-chromatography
  • colloidal silver
  • reproducible preparation
  • particle-size
  • scattering
  • spectroscopy
  • resonance

Cite this

Keir, R. ; Igata, E. ; Arundell, M. ; Smith, W.E. ; Graham, D. ; McHugh, C. ; Cooper, J.M. / SERRS. In situ substrate formation and improved detection using microfluidics. In: Analytical Chemistry. 2002 ; Vol. 74, No. 7. pp. 1503-1508.
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SERRS. In situ substrate formation and improved detection using microfluidics. / Keir, R.; Igata, E.; Arundell, M.; Smith, W.E.; Graham, D.; McHugh, C.; Cooper, J.M.

In: Analytical Chemistry, Vol. 74, No. 7, 01.04.2002, p. 1503-1508.

Research output: Contribution to journalArticle

TY - JOUR

T1 - SERRS. In situ substrate formation and improved detection using microfluidics

AU - Keir, R.

AU - Igata, E.

AU - Arundell, M.

AU - Smith, W.E.

AU - Graham, D.

AU - McHugh, C.

AU - Cooper, J.M.

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N2 - Surface-enhanced resonance Raman scattering (SERRS) of a model derivative of TNT was detected using a microflow cell designed within the framework of the lab-on-a-chip concept, using only the analyte and readily available reagents. The SERRS substrate, silver colloid, was prepared in situ, on-chip, by borohydride reduction of silver nitrate. The silver colloid was imaged within the chip using a white light microscope in either transmission or, due to the high reflectivity of the colloid, reflection mode. A fine stream of colloid similar to30 mum in width was formed in a 250-mum-wide channel at the point where the colloid preparation reagents met. The chip was designed to produce a concentrated stream of colloid within a laminar regime, such that particles did not readily disperse into the fluid. One result of this was to reduce the effective volume of analysis. Attempts to deliberately disrupt this stream with microstructured pillars, fabricated in the fluidic channels, were unsuccessful. The chip was also designed to have the appropriate dimensions for detection using a modern Raman microscope system, which collects scattering from a very small volume. A dye derived from TNT was used as a model analyte. Quantitative behavior was obtained over 4 orders of magnitude with a detection limit of 10 fmol. This performance is between 1 and 2 orders of magnitude better than that achieved using a macroflow SERRS cell. The technique has the added advantage that both reagent consumption and effluent production are greatly reduced, leading to reduced operating costs and a decreased environmental impact.

AB - Surface-enhanced resonance Raman scattering (SERRS) of a model derivative of TNT was detected using a microflow cell designed within the framework of the lab-on-a-chip concept, using only the analyte and readily available reagents. The SERRS substrate, silver colloid, was prepared in situ, on-chip, by borohydride reduction of silver nitrate. The silver colloid was imaged within the chip using a white light microscope in either transmission or, due to the high reflectivity of the colloid, reflection mode. A fine stream of colloid similar to30 mum in width was formed in a 250-mum-wide channel at the point where the colloid preparation reagents met. The chip was designed to produce a concentrated stream of colloid within a laminar regime, such that particles did not readily disperse into the fluid. One result of this was to reduce the effective volume of analysis. Attempts to deliberately disrupt this stream with microstructured pillars, fabricated in the fluidic channels, were unsuccessful. The chip was also designed to have the appropriate dimensions for detection using a modern Raman microscope system, which collects scattering from a very small volume. A dye derived from TNT was used as a model analyte. Quantitative behavior was obtained over 4 orders of magnitude with a detection limit of 10 fmol. This performance is between 1 and 2 orders of magnitude better than that achieved using a macroflow SERRS cell. The technique has the added advantage that both reagent consumption and effluent production are greatly reduced, leading to reduced operating costs and a decreased environmental impact.

KW - surface-enhanced raman

KW - flow-injection analysis

KW - silver electrode

KW - liquid-chromatography

KW - colloidal silver

KW - reproducible preparation

KW - particle-size

KW - scattering

KW - spectroscopy

KW - resonance

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DO - 10.1021/ac015625+

M3 - Article

VL - 74

SP - 1503

EP - 1508

JO - Analytical Chemistry

T2 - Analytical Chemistry

JF - Analytical Chemistry

SN - 0003-2700

IS - 7

ER -