Affinity detection of low molecular weight analytes

Area of Science:

• Biophysics
• Analytical Chemistry
• Materials Science

Background:

• Accurate detection of low molecular weight substance binding to protein sites is crucial for understanding molecular interactions.
• Optical methods offer label-free detection of biomolecular binding events.

Purpose of the Study:

• To directly detect and quantify the binding of biotin to streptavidin using reflectometric interference spectroscopy (RIFS).
• To establish the sensitivity and specificity of the RIFS method for analyzing molecular binding.

Main Methods:

• Utilized an optical transducer based on reflectometric interference spectroscopy (RIFS).
• Immobilized streptavidin onto a thin silica film surface.
• Measured changes in optical thickness upon incubation with biotin and benzoic acid.

Main Results:

• Successfully detected streptavidin immobilization (approx. 5 nm thickness increase).
• Quantified biotin binding as a ~70 pm thickness increase at 4 μM concentration.
• Determined a detection limit of 40 nM for biotin.
• Confirmed specificity by observing no significant change with benzoic acid.

Conclusions:

• RIFS is a highly sensitive and specific technique for directly detecting low molecular weight substance binding to protein sites.
• The method allows for unambiguous identification of molecular binding events with high resolution.
• This approach has potential applications in drug discovery and diagnostics.