DETERMINATION OF SIALIC ACID BY USING PLASMONIC NANOPARTICLES

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2022-6-22
AKIN, EDA
Sialic acids are an important sub-group of nine carbon acidic sugars. Sialic acid plays a significant role in mediating and modulating a variety of physiological activities due to its widespread distribution in human body. Several pathogens and toxins also bind to sialic acid, change its level and signal pathological conditions. The identification and quantification of sialic acid levels are also significant for early detection of many diseases such as breast and colon cancer. In this study, sialic acid determination in the form of N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) was aimed. Serotonin has specific affinity for sialic acid. Hence a novel detection strategy, which is based on the sialic acid-induced aggregation of serotonin functionalized gold nanoparticles, was proposed. Serotonin was bonded on gold nanoparticles utilizing two crosslinkers with different lengths: 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide / N-Hydroxysuccinimide (EDC/NHS) and Dithiobis(succinimidylpropionate) (DSP). Progressive additions of various sialic acid concentrations resulted in distinct color changes on serotonin modified gold nanoparticle probes (DSP-AuNPs@SER and EDC/NHS-AuNPs@SER) from red to purple and blue which indicates the affinity- aggregation. At optimal conditions while using EDC/NHS-AuNPs@SER probe, the absorbance ratio (A625/A521) was linear with respect to N-acetylneuraminic acid concentrations ranging from 300 to 750 µM. The limit of quantification 257.5 μM was achieved for Neu5Ac. Furthermore, at optimal conditions while using DSP-AuNPs@SER probe, the absorbance ratio (A625/A521) was linear with respect to N-acetylneuraminic acid concentrations ranging from 16.7 to 58.3 µM . The limit of quantification 10.0 μM was achieved for Neu5Ac. Moreover, at optimal conditions while using DSP-AuNPs@SER probe, the absorbance ratio (A625/A521) was linear with respect to N-glycolylneuraminic acid concentrations ranging from 8.3 to 58.3 µM . The limit of quantification 17.3 μM was calculated for Neu5Gc. Both probes were successful only for sialic acid among glucose, fructose, mannose, lactose, sucrose, and maltose. Applications of serotonin assembled gold nanoparticles in human serum to determine total serum sialic acid are in progress.

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Citation Formats
E. AKIN, “DETERMINATION OF SIALIC ACID BY USING PLASMONIC NANOPARTICLES,” M.S. - Master of Science, Middle East Technical University, 2022.