Magnetite-modified Gold Nanostars for Enhanced Uptake and SERS Detection of Tetracycline

Seojin Park^*
*Correspondence: Seojin Park, Department of Physical Materials Science, University of Science and Technology «MISIS», Moscow 119049, Russia, Email:

Introduction

In recent years, there has been growing interest in the development of advanced nanomaterials for a wide range of applications, from medical diagnostics to environmental monitoring and food safety. One area that has gained significant attention is the application of nanotechnology in the detection and monitoring of antibiotics in various environments. Among the many nanomaterials explored for these purposes, Gold Nanoparticles (AuNPs) have emerged as highly versatile candidates, owing to their excellent biocompatibility, tunable optical properties and ease of functionalization. However, the limited ability of bare gold nanoparticles to selectively target specific molecules and their suboptimal uptake in biological systems has motivated researchers to modify these particles to enhance their performance. One particularly promising strategy is the incorporation of Magnetite (Fe₃O₄) into gold nanostructures, which combines the advantages of both materials. Magnetite, a magnetic material, allows for the magnetic manipulation of nanoparticles, which can significantly improve the efficiency of their uptake by cells or tissues [1].

The incorporation of magnetite into gold nanostructures also opens the door to further enhancing their performance in sensing applications, especially in the realm of Surface-Enhanced Raman Spectroscopy (SERS). SERS, an ultrasensitive spectroscopic technique, is particularly well-suited for detecting trace amounts of molecules, such as antibiotics, due to its ability to amplify the Raman scattering signal of target molecules. The combination of magnetite-modified Gold Nanostars (AuNS) with SERS detection offers a unique platform for the sensitive, selective and non-invasive monitoring of small molecules, including antibiotics like tetracycline. Tetracycline is one of the most widely used antibiotics in both human medicine and animal husbandry and its presence in the environment, particularly in water sources, has raised significant public health concerns. Excessive tetracycline in the environment can contribute to the development of antibiotic-resistant bacteria, which poses a serious threat to global health [2].

Description

Gold nanostars are a subclass of gold nanostructures characterized by their star-like morphology. They are composed of a central core, typically made of gold, surrounded by multiple sharp tips or branches that extend radially outward. These tips give gold nanostars a highly anisotropic shape, which plays a critical role in their optical properties. The Surface Plasmon Resonance (SPR) of gold nanoparticles is highly sensitive to their size, shape and environment. The star-like structure of AuNSs enhances the localized electromagnetic field around the tips, which makes them particularly useful for applications in Surface-Enhanced Raman Spectroscopy (SERS). The high surface area-to-volume ratio of gold nanostars also provides ample opportunities for functionalization with various biomolecules, drugs and other compounds. This makes them ideal candidates for drug delivery, biosensing and diagnostic applications. The optical properties of gold nanostars, especially their ability to support intense plasmonic resonances, allow for a strong enhancement of Raman signals when used as substrates in SERS. Moreover, gold nanoparticles exhibit excellent biocompatibility, minimal cytotoxicity and can be easily modified with various ligands, making them well-suited for biological and medical applications [3].

Magnetite (Fe₃O₄) is a naturally occurring magnetic material that has been widely used in a range of applications, from biomedical imaging to drug delivery. The addition of magnetite to gold nanostars results in the formation of Magnetite-Modified Gold Nanostars (Fe₃O₄-AuNS),combining the unique properties of both materials. Magnetite imparts magnetic responsiveness to the gold nanostars, which allows for their easy manipulation using an external magnetic field. This can significantly enhance the uptake of these particles in biological systems, such as cells or tissues, by facilitating their targeted delivery and retention [4].

Surface-Enhanced Raman Spectroscopy (SERS) is a powerful analytical technique that allows for the detection of trace amounts of molecules by significantly amplifying their Raman scattering signal. SERS relies on the interaction of molecules with the plasmonic surface of nanoparticles, which leads to a dramatic increase in the intensity of the Raman scattering. This enhancement is primarily due to two mechanisms: electromagnetic enhancement and chemical enhancement. The former arises from the Localized Surface Plasmon Resonance (LSPR) of the nanoparticles, while the latter is due to charge transfer between the molecule and the nanoparticle surface. Gold nanostars are particularly effective in SERS applications due to their sharp tips, which concentrate the electromagnetic field and thus significantly enhance the Raman signal. The high surface area of gold nanostars also facilitates the adsorption of a wide range of molecules, including antibiotics like tetracycline. This makes AuNSs an excellent choice for the detection of small molecules, even at very low concentrations. Tetracycline, a broad-spectrum antibiotic, is frequently detected using SERS due to its strong Raman-active functional groups, which can be easily identified in the Raman spectra. However, for effective detection, it is crucial to enhance the interaction between tetracycline and the nanoparticle surface. Magnetite-modified gold nanostars offer a unique advantage in this regard, as the magnetite core not only improves the uptake of tetracycline but also contributes to the enhanced SERS signal by providing additional sites for molecular binding [5].

Conclusion

The development of magnetite-modified gold nanostars for enhanced uptake and SERS detection of tetracycline represents a promising advancement in the field of nanotechnology and biosensing. By combining the unique properties of gold nanostars with the magnetic characteristics of magnetite, these nanomaterials offer a highly effective platform for the detection of trace amounts of antibiotics like tetracycline. The ability to manipulate these particles using an external magnetic field significantly improves their uptake in biological systems, while the plasmonic properties of gold nanostars provide a strong enhancement of the Raman scattering signal, making SERS a powerful tool for antibiotic detection. This hybrid approach not only enhances the sensitivity of SERS-based detection but also offers the potential for targeted delivery and controlled release of antibiotics, paving the way for new diagnostic and therapeutic strategies. The ability to detect tetracycline and other antibiotics at low concentrations in complex biological and environmental samples could have far-reaching implications for public health, particularly in the context of antibiotic resistance.

Acknowledgement

None.

Conflict of Interest

None.

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