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Biofunctionalized gold nanoparticle-conducting polymer nanocomposite based bioelectrode for CRP detection
Sujeet K Mishra1, Vikash Sharma, Devendra Kumar
1CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi, 110012, India.
Insights
This study demonstrates an electrochemical impedance immunosensing method for detecting C-reactive protein (CRP) using a gold nanoparticle-polypyrrole nanocomposite film. The developed biosensor shows a linear response to CRP concentrations, offering a sensitive detection method.
Area of Science:
- Electrochemistry
- Nanomaterials Science
- Biomedical Engineering
Background:
- C-reactive protein (CRP) is a key biomarker for inflammation and cardiovascular disease.
- Accurate and sensitive detection of CRP is crucial for early diagnosis and monitoring of various health conditions.
- Existing CRP detection methods may lack sensitivity, speed, or cost-effectiveness.
Purpose of the Study:
- To develop and characterize a novel electrochemical impedance immunosensing platform for sensitive CRP detection.
- To immobilize anti-CRP antibodies onto a functionalized gold nanoparticle-polypyrrole nanocomposite film.
- To evaluate the performance of the developed immunosensor for CRP quantification in phosphate-buffered saline (PBS).
Main Methods:
- Fabrication of a nanocomposite film using electrochemically deposited gold nanoparticles (Au) capped with 3-mercaptopropionic acid (MPA) and polypyrrole (PPy) on an indium tin oxide (ITO) substrate.
- Site-specific immobilization of anti-CRP antibodies (Ab-αCRP) onto the carboxyl groups of the nanocomposite film using carbodiimide chemistry.
- Characterization of the nanocomposite film using atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), and electrochemical techniques.
- Electrochemical impedance spectroscopy (EIS) analysis using a modified Randles circuit to determine electron transfer resistance (R et) and other parameters.
Main Results:
- The Au(MPA)-PPy nanocomposite film exhibited a porous morphology, confirmed by AFM, HRTEM, and an electrochemical heterogeneity gauge (CPE exponent n=0.56).
- A stable immobilization of Ab-αCRP was achieved via an acyl amino ester linkage.
- A linear correlation was observed between the increase in electron transfer resistance (∆R et) and the logarithm of CRP antigen (Ag-αCRP) concentration over a range of 10 ng/mL to 10 μg/mL.
- The immunosensor demonstrated a high sensitivity of 46.27 Ω cm²/decade for CRP detection in PBS (pH 7.4).
Conclusions:
- The developed electrochemical impedance immunosensing method utilizing an Au(MPA)-PPy nanocomposite film is effective for sensitive and specific detection of CRP.
- The functionalized nanocomposite platform provides a robust surface for antibody immobilization and enhances the electrochemical signal.
- This approach offers a promising tool for the quantitative analysis of CRP in biological samples, potentially aiding in disease diagnosis.
Abstract:
An electrochemical impedance immunosensing method for the detection and quantification of C-reactive protein (αCRP) in phosphate buffered saline (PBS) is demonstrated. The protein antibody, Ab-αCRP, has been covalently immobilized on a platform comprising of electrochemically deposited 3-mercaptopropionic acid-capped gold nanoparticles Au(MPA)-polypyrrole (PPy) nanocomposite film of controlled thickness onto an indium tin oxide-coated glass plate. The free carboxyl groups present on the nanocomposite film have been used to site-specifically immobilize the Ab-αCRP biomolecules through a stable acyl amino ester intermediate generated by N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride and N-hydroxysuccinimide. The nanocomposite film was characterized by atomic force microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and electrochemical techniques. The bioelectrode was electrochemically analyzed using modified Randles circuit in terms of constant phase element (CPE), electron transfer resistance (R et), and Warburg impedance (Z w). The value of n, a CPE exponent used as a gauge of heterogeneity, for the Au-PPy nanocomposite film was found to be 0.56 which is indicative of a rather rough morphology and porous structure. A linear relationship between the increased ∆R et values and the logarithmic value of protein antigen, Ag-αCRP, concentrations was found in the range of 10 ng to 10 μg mL(-1) with a R et sensitivity of 46.27 Ω cm(2)/decade of [Ag-αCRP] in PBS (pH 7.4).
