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Optimization and Structural Stability of Gold Nanoparticle-Antibody Bioconjugates
Robert T Busch1, Farzia Karim1, John Weis1
1Department of Chemical and Materials Engineering, Department of Electro-Optics and Photonics, Department of Biology, Integrative Science and Engineering Center, and Department of Physics, University of Dayton, 300 College Park, Dayton, Ohio 45469, United States.
Optimizing antibody bioconjugation to gold nanoparticles (AuNPs) is crucial for sensitive bacterial detection. This study found pH 6 and MES buffer provide optimal conditions for stable antibody-AuNP biosensors, balancing efficiency and integrity.
Area of Science:
- Nanotechnology and Nanoscience
- Biomolecular Engineering
- Biosensor Development
Background:
- Gold nanoparticles (AuNPs) conjugated with biomolecules are key components in biosensor technology.
- Antibody-AuNP bioconjugates offer high sensitivity for bacterial detection.
- Understanding bioconjugate stability is vital due to harsh environmental conditions bacteria inhabit.
Purpose of the Study:
- To optimize the covalent bioconjugation of polyclonal antibodies to AuNPs for enhanced biosensor stability.
- To investigate the impact of varying pH conditions (2-11) and buffer types (MES, 3-(N-morpholino)propanesulfonic acid, NaOH, HCl) on antibody-AuNP conjugation.
- To identify the optimal conditions for maximizing antibody stability and adsorption efficiency on AuNPs.
Main Methods:
- Fourier-transform infrared (FTIR) spectroscopy to analyze antibody secondary structure stability (amide I and II regions).
- Transmission electron microscopy (TEM) to assess nanoparticle morphology, corona layer formation, and aggregation.
- UV-Visible spectroscopy to monitor wavelength shifts indicative of bioconjugation.
- Varied pH and buffer conditions to determine optimal bioconjugation parameters.
Main Results:
- Antibody secondary structure stability decreased significantly at lower pH values (down to pH 2).
- Antibody adsorption efficiency varied with pH, peaking at 27% between pH 2-6 before declining at higher pH.
- Optimal corona layer formation (5.1 nm) and minimal aggregation were observed at pH 6, with incomplete corona at pH 7.9 and larger layers at pH 11.
- Lower pH favored covalent binding efficiency but led to antibody aggregation and deactivation.
Conclusions:
- The optimal condition for antibody-AuNP bioconjugation was determined to be pH 6 using MES buffer.
- This condition balances efficient covalent bonding and preserves antibody secondary structure stability.
- The optimized bioconjugation method yields stable antibody-AuNP conjugates suitable for sensitive biosensor applications.
