Mohammad Reza Mohammad Shafiee; Janan Parhizkar
Abstract
Objective: The annual incidence of cancer in the world is growing rapidly. The most important factor in the cure of cancers is their early diagnosis. miRNA, as a biomarker for early detection of cancer, has attracted a lot of attention. Methods: In this study, an electrochemical biosensor was developed ...
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Objective: The annual incidence of cancer in the world is growing rapidly. The most important factor in the cure of cancers is their early diagnosis. miRNA, as a biomarker for early detection of cancer, has attracted a lot of attention. Methods: In this study, an electrochemical biosensor was developed to detect the amount of miR-106a, the biomarker of gastric cancer, by modifying a glassy carbon electrode (GCE) with a composite of graphitic carbon nitride and gold nanoparticles. Complementary DNA strand of miR-106a which modified with biotin was used as a probe. Nanoparticles of titanium phosphate modified with Streptavidin and zinc ions were used to generate the electrochemical signal in square wave voltammetry. To characterize the g-C3N4 functional group, the chemical composition of the titanium phosphate nanoparticles, the morphology and elemental composition of composite Fourier transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and Energy Dispersive X-Ray Spectroscopy (EDS) were used, respectively. Results: The peaks of C, N, and Au in EDS spectrum confirmed composite formation. The linear range and detection limit of the modified biosensor for miRNA-106a were obtained from 0.6 to 6.4 nM and 80 pM, respectively. Conclusion: Ultimately, Au nanoparticles/ g-C3N4 composite modified electrode can be a good platform for making electrochemical biosensor to diagnosis cancer in early stages.
Yasamin Davatgaran Taghipour; Sharmin Kharrazi; Seyed Mohammad Amini
Abstract
In this paper, a fast and sensitive localized surface plasmon resonance (LSPR) based biosensor was developed and the optimization of gold – antibody conjugates through investigation of different parameters were performed. Gold nanoparticles (AuNPs) with a size of ~20 nm were synthesized via chemical ...
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In this paper, a fast and sensitive localized surface plasmon resonance (LSPR) based biosensor was developed and the optimization of gold – antibody conjugates through investigation of different parameters were performed. Gold nanoparticles (AuNPs) with a size of ~20 nm were synthesized via chemical reduction of HAuCl4 with trisodium citrate as reducing and stabilizing agent. The impacts of pH of gold colloids and antibody concentrations on conjugation of electrostatically absorbed antibodies on the AuNPs surface were evaluated. The diverse amounts of antigens were added to the selected gold – antibody conjugate and the calibration curve and limit of detection of the system were successfully obtained. The UV- Vis and DLS outputs were utilized to prove the efficiency and repeatability of the system. As a result, the designed biosensor shows a convincing LOD of 400 ng/ml of antigen. It is suggested that electrostatic absorption strategy of AuNPs with negative charge to the positively charged antibodies can be an efficient methodology. Results showed an effective LSPR system for detection of small amounts of antigen in short time as well as with high accuracy.
