Posted by A biosensor is a device that measures a biological or chemical reaction by producing a signal that is proportional to the concentration of the analyte in the reaction. Biosensors are used in disease monitoring, drug development, and detection of pollutants, pathogenic microorganisms, and disease-indicating markers in body fluids (blood, urine, saliva, sweat). A typical biosensor is shown in Figure 1 and consists of the following components: analyte, bioreceptor, sensor, electronics, and display. Some popular areas of application of biosensors include in the food industry, for checking their quality and safety, helping to differentiate between natural and artificial; in the fermentation industry and saccharification processes, for detecting precise glucose concentrations; and in metabolic engineering, for use in Monitor cell metabolism in vivo. Biosensors and their role in medical science, including early detection of heart disease caused by human interleukin 10 and rapid detection of human papillomavirus, are important aspects.
Previously reported biosensors have some essential limitations due to the use of biomolecules, such as low electrochemical signal intensity, instability, and low sensitivity generated by biomolecule reactions. In order to solve these problems, some materials, including conductive polymers and porous materials, have been introduced to immobilize biomolecules to increase the electron transfer reaction of biomolecules and maintain their biomolecule activity. In recent years, nanomaterials have attracted great attention in many scientific fields, especially in biology due to their properties such as high conductivity and biocompatibility. It is well known that the advantages of nanomaterials include expanded active surface area and the creation of new features that do not exist in the bulk state. Polystyrene fluorescent particles have good biocompatibility. Researchers have prepared fluorescent polystyrene nanoparticles of different sizes and applied them in fluorescence analysis. As an amplification material for fluorescent signals, they have been widely used in biosensors and other fields.
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Advantages of Using Fluorescent Polystyrene Particles in Biosensing
- High brightness and tunable emission wavelengths for multiplexing
Fluorescent polystyrene particles have extraordinary brightness compared to other labels. This translates into stronger signals in biosensing assays, resulting in increased sensitivity and easier detection of target molecules. A brighter signal also minimizes background noise, improving the accuracy of your results. These particles have a wide range of tunable emission wavelengths, meaning they can emit different colors of light when excited. This allows the creation of multiplexed biosensors capable of detecting multiple biomolecules simultaneously in a single test.
- Large surface area for efficient biomolecule immobilization
Fluorescent polystyrene particles have significantly larger surface areas compared to other commonly used biosensing labels. This expanded real estate provides ample space for immobilizing biomolecules such as antibodies, enzymes, or DNA probes. The more biomolecules you can attach, the more targets your sensor is likely to detect, thus increasing the sensitivity of the detection. The larger surface area also allows for the attachment of more complex combinations of biomolecules. This enables researchers to create highly specific biosensors designed to bind only to their target molecules of interest, minimizing the risk of false positives.
- Biocompatibility and ease of functionalization
Polystyrene fluorescent particles are known for their biocompatibility, meaning they are less likely to cause adverse reactions within biological systems. This makes them ideal for biosensing applications where interaction with biological samples is critical. The surface of these particles can be easily functionalized with various chemical groups. This allows researchers to tailor the properties of the particles to specifically bind to the desired biomolecules, creating highly customized biosensors for different applications.
A Glimpse into Biosensing Applications
- Detection of biomarkers
Fibrinogen participates in a variety of physiological processes and is a biomarker for many diseases. Therefore, it is particularly important to develop a sensitive fibrinogen detection method. Chen et al. developed a new color-coded single-particle detection (SPD) method (Figure 2) for the detection of fibrinogen, using platelet membrane-coated fluorescent polystyrene nanoparticles (PNPs) as probes (green and red fluorescent carboxyl polystyrene nanoparticles, 200 nm in size). For the detection of fibrinogen, the sensor has a linear range of 30-300 μg/mL and a LOD of 3.9 μg/mL. Furthermore, this biosensor has been verified to selectively detect fibrinogen and showed good performance in real sample applications.
- Invisible security ink
Sonawane et al. prepared color-tunable solid-state emitting polystyrene (PS) microspheres through dispersion polymerization. The microspheres have good fluorescent safety ink properties and can sensitively detect vapors of nitro aromatics like 4-nitro toluene (4-NT). Ethanol dispersions of the polymer can be used directly as fluorescent security “invisible” inks that are only visible under UV light (Figure 3). The color of the ink can be adjusted based on the amount of pyrene and perylenebisimide. The ease of synthesis of this material, its invisible ink properties, and nitro aromatic vapor detection open new opportunities to explore the application of these polystyrene-based materials as optical sensors and fluorescent inks for security purposes.
- Food safety testing
Tang et al. established a highly sensitive time-resolved fluorescent immunochromatographic assay (TRFICA), which can detect aflatoxin M1 (AFM1) in raw milk within 6 minutes using 190 nm-based europium microbeads (Figure 4) without any sample pretreatment. This method can meet the requirements of dairy farms and the dairy industry for rapid and sensitive monitoring of milk. Based on the competitive format and the homemade anti-AFM1 mAb 2C9, this method improves the sensitivity from 0.3ng/mL (using the previously reported nanogold test strip method) to 0.03ng/mL (TRFICA method).
The application of fluorescent polystyrene particles in biosensors provides opportunities to build a new generation of biosensor technology. Polystyrene particles have improved the mechanics, electrochemistry, and optics of biosensors and are developing toward single-molecule biosensors for high-throughput biosensor arrays. How to make full use of the structures and functions of polystyrene particles and biomolecules to prepare single-molecule multifunctional nanocomposites, nanofilms and nanoelectrodes remains a huge challenge.
References
- Bhalla, N., Jolly, P., Formisano, N., & Estrela, P. (2016). Introduction to biosensors. June, 1–8.
- Yoon, J., Shin, M., Lee, T., & Choi, J. W. (2020). Highly sensitive biosensors based on biomolecules and functional nanomaterials depending on the types of nanomaterials: A perspective review. Materials, 13(2), 299.
- Chen, D., Song, Z., Lian, M., Yang, Y., Lin, S., & Xiao, L. (2021). Single-particle fibrinogen detection using platelet membrane-coated fluorescent polystyrene nanoparticles. Nanoscale, 13(5), 2914-2922.
- Sonawane, S. L., & Asha, S. K. (2016). Fluorescent polystyrene microbeads as invisible security ink and optical vapor sensor for 4-nitrotoluene. ACS applied materials & interfaces, 8(16), 10590-10599.
- Tang, X., Zhang, Z., Li, P., Zhang, Q., Jiang, J., Wang, D., & Lei, J. (2015). Sample-pretreatment-free based high sensitive determination of aflatoxin M 1 in raw milk using a time-resolved fluorescent competitive immunochromatographic assay. RSC advances, 5(1), 558-564.