Identifying and
detecting health hazards in food products, especially contaminants and toxic
substances such as allergens, food toxins and agricultural residues from
pesticides, remains a challenge. Increasing demand for food products and
growing health consciousness necessitate rapid and accurate
measurements which can be easily conducted on-site without long measurement
times and high costs. Due to their ease of use, accuracy sample preparation and
rapidity, biosensors have started to outcompete time-consuming lab-scale analytical
devices. However, as the use of biosensors increase, a concern of the
amount of plastics and synthetic polymers used in the fabrication of these
biosensors rises. In this dissertation, new ways to create biodegradable and
eco-friendly plant-based SERS biosensor platforms from corn protein, zein, are
presented. Its higher hydrophobicity and film forming capability make zein a
very suitable biopolymer for fabricating biosensors. In the first part of this
dissertation, chemical crosslinking was tested to improve the surface
hydrophobicity, surface roughness (using AFM), mechanical properties, kinetics
of gelation and film formation of zein films, and as a result zein-film based
SERS platforms with fewer defects could
be fabricated. In the second part, the detection sensitivity of the zein film-based
SERS platforms was increased with metallic nanoparticle decoration (gold, silver
or silver-shelled-gold). The addition of all three types of nanoparticles
significantly increased the SERS enhancement factors of the platforms, with
silver-shelled-gold nanoparticles giving the highest enhancement factor of 10<sup>5</sup>.
In the last part of this thesis, a novel approach was tested, where electrospun zein
nanofibers decorated with metallic nanoparticles were used as a SERS biosensor
platform. Due to their higher surface area-to-volume ratios, electrospun zein
nanofibers gave a higher SERS enhancement factor (10<sup>6</sup>). This
enhancement factor enabled the detection of acrylamide, a food carcinogen, with
a 10<sup>4</sup> times lower detection limit than nanophotonic
based nanoimprinted zein, acrylamide sensor platform. Overall,
this dissertation successfully shows the fabrication of biodegradable and
eco-friendly SERS sensor platforms that have comparable detection sensitivities
to those of non-biodegradable ones.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12567728 |
| Date | 26 June 2020 |
| Creators | Hazal Turasan (9028997) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/Fabrication_of_zein-based_biodegradable_surface_enhanced_Raman_spectroscopy_biosensor_platforms_for_the_detection_of_food_toxins/12567728 |
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