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Application of Cellulose Nanofibers Coated Quartz Crystal Microbalance (QCM)Biosensor for Amino Acid Detection in Aqueous Media

Hosseini, Marzieh Sadat | 2023

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 56137 (48)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Iraji Zad, Azam; Vossoughi, Manouchehr
  7. Abstract:
  8. Developing a simple, cost effective and accurate detection method for L-lysine (Lys), L-leucine (Leu) and glycine (Gly) as the important analytes in clinical diagnostics, biological processes and food industries is of great interest. Therefore, in the first part of this research, cellulose nanofibrils (CNFs) were coated on a quartz crystal microbalance (QCM) surface by spin coating to achieve a QCM biodetector for Gly. Thus, the two-layer CNFs coating was selected as sensing film and was applied for following experiments. In the next step, the coated QCMs were carefully characterized before and after interaction with Gly using water contact angle (WCA), Fourier transform infrared spectrophotometry-attenuated total reflectance (FTIR-ATR), Raman spectroscopy, and scanning electron microscopy (SEM). The stable and fully covered QCMs without further modification were then successfully applied for aqueous glycine detection. Different concentrations (3–1000 μg/mL) of glycine were studied. The resonance frequency shifts obtained from the samples during each step of the measurement are presented and discussed. The data shows a linear range of detection (R2= 0.9889) for 3–1000 μg/mL of glycine and a limit of detection (LOD) of about 136 μg/mL. Therefore, the CNF coated QCM has potential application as a biodetector for glycine detection. According to the results of the first part and the study of the behavior of the sensor against Gly, in the second part, to improve the sensitivity of the sensor, TEMPO oxidized cellulose nanofibers (TOCNFs) were coated instead of TOCNFs on the QCM surface as a sensing layer and were investigated. The coated QCMs were applied to detect Lys, Gly and Leu. They were carefully characterized before and after interaction with target amino acids (AA) using the same characterization techniques as the first research. Then, the frequency reductions of the detectors in proportion to different AA concentrations (10-1000 μg/mL) of aqueous target analytes were studied. The data shows a linear range of detection R2= 0.9987, 0.9933, 0.9833 and calculated limit of detection (LOD) equal to 48, 112 and 158 µg/ml for Lys, Gly and Leu, respectively. The highest frequency shifts (strongest interaction with TOCNFs) was observed for Lys detection while response to Leu was negligible. Therefore, the biodetector was more sensitive to Lys. Also, by changing the sensing layer from CNFs to TOCNFs, the sensitivity of the detector to Gly increased and LOD was improved
  9. Keywords:
  10. Glycine ; L-Leucine (Leu) ; Amino Acid ; TEMPO-Oxidized Cellulose Nanofibrils (TOCNFs) ; Quartz Crystal Microbalance (QCM)Biosensor ; Biosensor ; Equeous Media

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