Thickness Determination and Control in Protein-Based Biomaterial Thin Films

Area of Science:

• Biomaterials Science
• Spectroscopy
• Protein Engineering

Background:

• Precise control over biomaterial film thickness and uniformity is essential for applications in sensing and bioelectronics.
• Engineered repeat proteins, such as consensus tetratricopeptide repeat (CTPR) proteins, offer robust and tunable properties for biomaterial development.

Purpose of the Study:

• To evaluate microreflectance spectroscopy and apparent color inspection as rapid, non-invasive methods for assessing the thickness and uniformity of CTPR protein films.
• To compare microreflectance spectroscopy with established techniques like ellipsometry and atomic force microscopy for film thickness characterization.
• To provide a calibration guide for preparing CTPR films with specific thicknesses.

Main Methods:

• Microreflectance spectroscopy was employed to measure the thickness of spin-coated and drop-casted CTPR protein films on oxidized silicon substrates.
• Apparent color inspection was used to assess the uniformity of the protein films.
• Results from microreflectance spectroscopy were validated against ellipsometry and atomic force microscopy.

Main Results:

• Microreflectance spectroscopy showed excellent agreement with ellipsometry and atomic force microscopy, confirming its effectiveness for determining biomaterial film thickness.
• The technique was successfully applied to characterize thinner, less uniform drop-casted films prepared from small solution volumes.
• Apparent color inspection proved useful for evaluating film uniformity.
• A calibration was established relating film thickness to protein length and concentration for both spin-coated and drop-casted films.

Conclusions:

• Microreflectance spectroscopy is a fast, non-invasive, and affordable method for assessing the thickness and uniformity of CTPR protein films.
• The reproducibility of CTPR film assembly allows for the straightforward preparation of biomaterial films with controlled thickness.
• These findings facilitate the precise fabrication of protein-based biomaterials for advanced applications.