Abstract
The objective of this thesis was to study patterned
substrates and gold nanoparticles as surface-enhanced
Raman spectroscopy tools for label-free detection of
biological analytes with high sensitivity and easy sample
handling. There are many fields, such as environmental
monitoring, medical analysis, food safety and national
security, which currently lack a rapid analysis tool for
bioanalyte recognition. This thesis concentrated on
applying disposable singleuse surface-enhanced Raman
scattering (SERS) substrates for the detection of
microbial cells and small molecules. The substrates were
patterned with roll-toroll (R2R) UV replication. R2R
fabrication of the SERS substrates enables industrial
scale manufacturing of large sensor areas in a repeatable
manner. SERS detection is based on the recording of
inelastically scattered photons. The scattering is
enhanced locally by a resonance effect of the surface
plasmons of noble metal surfaces. SERS can achieve
sensitive detection of low analyte volumes, even in the
range of a few particles. In addition, it has the
advantage of label-free detection due to the fingerprint
spectrum, in which the signal reveals information
concerning the composition of the molecules forming the
analyte. In this study the SERS substrates were combined
with metal nanoparticles and
the samples were concentrated with hydrophobic materials.
The sample intake to the chip was developed for the
detection of rhodamine 6G inside an optofluidic SERS
chip. The behaviour of small molecules in the flow was
studied through a polymer lid with microfluidic circuits
attached to SERS substrates. The second topic
concentrated on detection of Listeria innocua ATCC 33090
bacterial cells with SERS substrates and gold
nanoparticles. The limit of
detection (LOD) was found to be approx. 2·104 CFU/ml. In
the third topic, the effect of the shape and composition
of the nanoparticles on the SERS detection of yeast was
studied with three yeast strains originating from the
beverage industry: Wickerhamomyces anomalus,
Brettanomyces bruxellensis and Rhodotorula mucilaginous.
A specific Raman spectrum was detected for all of the
strains.
| Original language | English |
|---|---|
| Qualification | Doctor Degree |
| Awarding Institution |
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| Supervisors/Advisors |
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| Award date | 24 Nov 2017 |
| Place of Publication | Espoo |
| Publisher | |
| Print ISBNs | 978-951-38-8577-9 |
| Electronic ISBNs | 978-951-38-8576-2 |
| Publication status | Published - 2017 |
| MoE publication type | G4 Doctoral dissertation (monograph) |
Keywords
- SERS substrate
- nanoimprint lithography
- disposability
- microbial cells
- nanoparticles