Calibration Curve Approaches for Nonlinear Data Points Obtained in Colo 320 Exosomes Determination

Document Type : Original Article


1 Department of Medical Services and Techniques, Ankara Medipol University, 06050, Ankara, Turkey

2 Graduate School of Natural and Applied Science, Gazi University, 06560, Ankara, Turkey

3 Faculty of Pharmacy, Department of Analytical Chemistry, Gazi University, 06330, Ankara, Turkey

4 Department of Histology and Embryology, Manisa Celal Bayar University, 45030, Manisa, Turkey

5 DESAM Institute, Near East University, Mersin 10, Turkey

6 Faculty of Science, Department of Chemistry, Gazi University, 06560, Ankara, Turkey


The limit of detection (LOD) is defined as the lowest quantity or concentration of a component that can be reliably distinguished from the limit of blank (LOB). LOD value is one of the most important parameters considered for many determination methods and is usually calculated on the linear correlation between signal and concentration. However, the linear correlation may not always be obtained in experimental studies. We claim that data with low linear correlation have meaning, and we present such a study because analytical studies based on these data are not easily understood in the literature. In this manuscript, we suggest that a calibration curve can be obtained from nonlinear data points and the LOD value can be calculated. We tested this approach for the determination of exosomes and supported it with mathematical calculations. We produced a label-free sensor using anti-CD63 on the gold electrode for selective and reliable impedimetric detection of the exosomes obtained from Colo 320 cell lines in data points that are high concentrations and out of linearity. We characterized in detail what each calculation means. This sensor with a LOD value of 3.90×1011 exosome particles µL-1 and with a cubic polynomial model for the calibration curve was considered sensitive and reliable, especially for high vesicle content of samples such as cell culture medium.


Volume 14, Issue 11
November 2022
Pages 1027-1043
  • Receive Date: 01 September 2022
  • Revise Date: 17 November 2022
  • Accept Date: 23 November 2022
  • First Publish Date: 30 November 2022