Zein's amphiphilic properties, film forming capability, and biodegradability make it a highly demanded polymer for fabrication of packaging materials, production of drug carrier nanoparticles, scaffolds in tissue engineering, and formation of biodegradable platforms for biosensors including microfluidic devices. Zein properties can be improved by chemical modifications, which are often analyzed with spectroscopic techniques. However, there is not a consensus on the structure of zein. For this reason, in this Review the aim is to compile the recent studies conducted on zein-based products and compare them under five main spectroscopic techniques: Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, circular dichroism (CD), X-ray diffraction (XRD) and atomic force microscopy (AFM). This Review serves as a library of recent zein studies and helps readers to have a better perception of contradictions in the literature to take their studies one step further.
In this paper, a biodegradable gold
coated zein film surface enhanced
Raman spectroscopy (SERS) platform, with gold nanoparticles (AuNPs)
deposited on the surface to further enhance the Raman signal, was
used to detect pyocyanin (PYO), the toxin secreted by Pseudomonas aeruginosa. An inverted pyramid structure
imprinted on a zein film and gold coated during the transfer process
was further improved with the deposition and fixing of gold nanoparticles,
which resulted in enhancement of the SERS signal by approximately
a decade. This new platform served as a lab-on-a-chip sensor to enable
the sensitive and rapid detection of PYO in drinking water. The size,
distribution, and morphology of the zein film nanostructures including
the presence and distribution of gold nanoparticles were characterized
by scanning electron microscopy (SEM). The new zein-based platform
has the advantage of being largely biodegradable compared with commercial
silicon- or glass-based platforms. The limit of detection for PYO
using the newly developed zein-based SERS sensor platform was calculated
as 25 μM, considerably lower than the concentration of PYO in
the blood of people with cystic fibrosis which has been reported to
be 70 μM.
An increasing number of foodborne outbreaks, growing consumer desire for healthier products, and surging numbers of food allergy cases necessitate strict handling and screening of foods at every step of the food supply chain. Current standard procedures for detecting food toxins, contaminants, allergens, and pathogens require costly analytical devices, skilled technicians, and long sample preparation times. These challenges can be overcome with the use of biosensors because they provide accurate, rapid, selective, qualitative, and quantitative detection of analytes. Their ease of use, low-cost production, portability, and nondestructive measurement techniques also enable on-site detection of analytes. For this reason, biosensors find many applications in food safety and quality assessments. The detection mechanisms of biosensors can be varied with the use of different transducers, such as optical, electrochemical, or mechanical. These options provide a more appropriate selection of the biosensors for the intended use. In this review, recent studies focusing on the fabrication of biosensors for food safety or food quality purposes are summarized. To differentiate the detection mechanisms, the review is divided into sections based on the transducer type used.
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