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Fiber optic biosensors, particularly those powered by surface plasmon resonance technology, have been applied to a wide variety of different biological applications. Within the food safety industry, the advancements made in fiber optic surface plasmon resonance (FOSPR) biosensor technology have allowed these analytical tools to provide researchers with precise measurements on the concentrations and physical characteristics of genetically modified organisms (GMOs) present in different food products.
Fiber Optic Surface Plasmon Resonance Biosensor
Since its original debut in 1993, fiber optic surface plasmon resonance (FOSPR) technology has continued to gain a significant amount of attention as a result of its compact nature, ease of incorporation into hand-held analytical instruments, as well as label-free and real-time analytical capabilities.
The basic working principle behind SPR technology depends upon a light source that is used to simulate the oscillation of electrons into a metal film. As these electrons continue to move in response to the absorbed light, they form an electronic field that eventually decays into its surrounding environment.
FOSPR sensitivity is primarily determined by the type of metal film being used, as well as the change of the refractive index that occurs at the surface of the biosensor.
FOSPR Biosensor Applications in Biology
When applied within the field of biological sciences, FOSPR biosensors have been employed for a variety of purposes that require the detection of biological molecules such as proteins, antigens, oligonucleotides and metabolic substances.
To improve the sensitivity of FOSPR biosensors, scientists have investigated different ways in which they can manipulate the changes of the refractive index that occur at the FOSPR surface. For example, scientists have found that the incorporation of nanotechnology into FOSPR biosensors in the form of gold nanoparticles, silver nanoparticles and graphene has improved various aspects of the analytical capabilities of these instruments.
FOSPR and Nucleic Acid Detection
The ability of FOSPR biosensors to accurately detect and measure nucleic acid concentrations is a critical aspect of a wide range of biological areas of interest, ranging from medical diagnostics to environmental and food safety monitoring. To this end, the primary nucleic acid biomarkers that are used for these purposes include DNA, mRNA and microRNA.
The preliminary analysis of food products that typically occurs prior to their distribution to consumers often depends upon the ability to obtain accurate nucleic acid biomarker measurements. With this type of information, food manufacturers can better identify the presence of potentially pathogenic bacteria and/or genetically modified organisms (GMOs) that may be present within the food product.
Current Limitations of FOSPR Biosensors
To increase the sensitivity and capabilities of these detection methods, SPR techniques are often accompanied by other analytical methods, including polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), exponential amplification reaction (EXPAR), ligase chain reaction and nuclease or nicking enzyme-assisted amplification. Unfortunately, many of the aforementioned analytical techniques often require tedious sample preparation. In addition, subtle changes in the pH, temperature and/or buffer composition of the analyte can also prevent accurate results from being obtained.
Why Test for GMOs?
GMOs arise as a result of the introduction of a modified genome into an existing organism. By incorporating one or more exogenous genes into the existing genome of the organism, new characteristics can arise, depending upon the needs of the food manufacturer conducting these genetic alterations. For example, food manufacturers may be interested in improving the tolerance of their plants to herbicides and/or drought, as well as improve their resistance to diseases and/or pests.
While genetically modifying food products may lead to cost-effective solutions for farmers by increasing their yield or limiting their use of herbicides, there are certain health risks that can result following human exposure to these GMOs.
Novel FOSPR Biosensor for GM Food Testing
The main purpose of testing food products for the presence of GMOs is to therefore provide consumers with as accurate information on the exact contents of their food products.
In 2018, a group of researchers from the Sichuan University in Chengdu, China, presented their findings on a novel FOSPR biosensor that was shown to accurately detect the presence of GMOs in food products.
The Sichuan team designed their FOSPR biosensor to be equipped with dual signal amplification that was supported by target recyclic amplification strategy and rGO-AuNPs. This biosensor, which is enzyme-, PCR amplification- and label-free, successfully detected the presence of GMOs in food products at concentrations as low as 12 picoMolar (pM).
Moreover, the FOSPR biosensor discussed here was found to provide a greater sensitivity and specificity towards single stranded DNA (ssDNA) as compared to traditional analytical techniques.
References and Further Reading
- Chen, Z., Chengjun, S., Zewei, L., Kunping, L., Xijian, Y., Haimin, Z., Youngzin, L., & Yixiang, D. (2018). Fiber optic biosensor for detection of genetically modified food based on catalytic hairpin assembly reaction and nanocomposites assisted signal amplification. Sensors and Actuators B: Chemical; 956-965. DOI: 10.1016/j.snb.2017.07.174.
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