Synthesis and Characterization of Heptamethine Indocyanine Dyes Coupled with Quick-Freezing Induced Aggregation AuNPs (QFIAAs) for Improved Screening by Near-IR (NIR) Surface-Enhanced Raman Scattering (SERS)
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Publication Date
24-4-2023
Degree Name
Forensic Science, M.S.
Department
Chemistry Department
School
School of Arts and Sciences
Description
Near Infra-red (NIR) Surface-Enhanced Raman Spectroscopy (SERS) is an emerging technique widely used in bioimaging due to its high-resolution output compared to other methods. Recently the FDA approved Indocyanine Green, a NIR optical marker, for detecting cancerous tissue in clinical screening. Indocyanine Green has an absorbance maximum of >750 nm making it a unique probe also suitable for determining cardiac output, hepatic function, liver, gastric blood flow, and ophthalmic angiography. Despite the high demand for Raman active near-IR sensitive molecules in bioimaging, the development of ultrasensitive SERS is still daunting due to its availability, sensitivity, and reproducibility. A library of heptamethine cyanine dyes was synthesized by nucleophilic substitutions of Meso-chloride with different amines. Subsequently, the secondary amine was derivatized by introducing functionally diverse chemical substituents. We hypothesized that the resonating effect of the functional substituent in the amine would govern the enhanced NIR-SERS activity of the compounds. Following the synthesis, the dye molecules were individually coupled with citrate-capped, QFIAAs (Quick Freezing Induced Aggregation AuNPs) to enhance the NIR-SERS signal during Raman analysis. Raman signal produced showed a relationship between UV/Visible absorbance intensity and relative position to 780 nm wavelength of a dye.
Synthesis and Characterization of Heptamethine Indocyanine Dyes Coupled with Quick-Freezing Induced Aggregation AuNPs (QFIAAs) for Improved Screening by Near-IR (NIR) Surface-Enhanced Raman Scattering (SERS)
Near Infra-red (NIR) Surface-Enhanced Raman Spectroscopy (SERS) is an emerging technique widely used in bioimaging due to its high-resolution output compared to other methods. Recently the FDA approved Indocyanine Green, a NIR optical marker, for detecting cancerous tissue in clinical screening. Indocyanine Green has an absorbance maximum of >750 nm making it a unique probe also suitable for determining cardiac output, hepatic function, liver, gastric blood flow, and ophthalmic angiography. Despite the high demand for Raman active near-IR sensitive molecules in bioimaging, the development of ultrasensitive SERS is still daunting due to its availability, sensitivity, and reproducibility. A library of heptamethine cyanine dyes was synthesized by nucleophilic substitutions of Meso-chloride with different amines. Subsequently, the secondary amine was derivatized by introducing functionally diverse chemical substituents. We hypothesized that the resonating effect of the functional substituent in the amine would govern the enhanced NIR-SERS activity of the compounds. Following the synthesis, the dye molecules were individually coupled with citrate-capped, QFIAAs (Quick Freezing Induced Aggregation AuNPs) to enhance the NIR-SERS signal during Raman analysis. Raman signal produced showed a relationship between UV/Visible absorbance intensity and relative position to 780 nm wavelength of a dye.
