Quantifying Bound Proteins on Pegylated Gold Nanoparticles Using Infrared Spectroscopy

Area of Science:

• Biomaterials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Protein-nanoparticle (NP) complexes are vital nanomaterials for biosensing and nanomedicine.
• Accurate quantification of bound proteins per NP is challenging, especially for metal NPs that interfere with standard assays.
• Characterizing protein-NP conjugates is critical for optimizing their performance in biomedical applications.

Purpose of the Study:

• To develop a robust method for quantifying proteins bound to nanoparticles.
• To provide a characterization technique that circumvents issues with metal nanoparticle interference.
• To establish a generalizable method for determining protein-NP ratios.

Main Methods:

• Utilized infrared (IR) spectroscopy to quantify proteins bound to pegylated thiol-capped gold nanoparticles (AuNPs).
• Leveraged distinct IR absorption bands of proteins and capping ligands for ratio determination.
• Avoided nanoparticle degradation, enabling direct analysis of the conjugate.

Main Results:

• Successfully quantified protein-NP ratios using IR spectroscopy.
• Demonstrated that the method is effective even with metal nanoparticles.
• Showcased the generalizability of the method using bovine serum albumin (BSA) for calibration.

Conclusions:

• Infrared spectroscopy offers a viable and accessible method for quantifying protein-NP ratios.
• This technique simplifies characterization, facilitating advancements in protein-nanoparticle conjugate development.
• The method's generalizability allows for the quantification of various proteins on nanoparticles.