The Optimization of Gold Coated Iron Nanoparticle Synthesis Methods
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The field of nanomedicine is rapidly growing as the applications of incorporating micro-structured systems into treatment and diagnosis of diseases are being discovered and refined. A “bottom-up” approach to building molecular networks is becoming more common with the increase in available methods that allow for utilization of self-assembly or ordered chemistry at the particle level. Biosensors are medical devices that have employed such systems, and the biosensor market is on the rise as the focus of patient evaluation shifts to point-of-care diagnosis. Successful implementation of these structures into a biosensor is not simple, since reproducibility and sensitivity are paramount in such devices. Those characteristics are contingent on the use of materials that are highly consistent, and tailor-made for a specific biosensor analysis. Among the materials frequently employed in the fabrication of nanoparticle systems, gold is one of the most popular. Gold has a defined affinity for sulfur, which gives a gold surface the potential for functionalization if a thiolated ligand is used. However gold is rare and costly, and cannot be used frivolously when designing a synthesis method for gold nanoparticle production that is also scalable. Therefore it is desirable to identify and optimize the best synthesis method for this task. In this paper, an approach is taken to optimize the best-suited method for synthesizing gold-coated iron nanoparticles. The gold coating provides a means to functionalize the nanoparticle for use in a large variety of biosensors, and the magnetic nature of the particles allow for concentration of analytes in a sample, which improves inherent biosensor sensitivity. Resulting products of this “modified synthesis” were analyzed and evaluated using characterization methods such as scanning electron microscopy, ultraviolet-visible spectroscopy, and vibrating scanning magnetization. Improvements in particle size control and reduced use of expensive reagents were obtained. The nanoparticles produced did not meet the necessary size variance, particle dispersity, and coating uniformity required for implementation in a current biosensor process.