A low-cost method for visible fluorescence imaging

Area of Science:

• Biophysics
• Structural Biology
• Crystallography

Background:

• Screening crystallization conditions is crucial for obtaining diffraction-quality crystals.
• Automated imaging systems for crystal screening are prohibitively expensive for many labs.
• A cost-effective imaging solution is needed to assess crystallization plates.

Purpose of the Study:

• To develop and validate a simple, inexpensive method for imaging trace fluorescently labeled protein crystals.
• To demonstrate the feasibility of using smartphone macro lens attachments for crystal imaging.
• To provide an accessible alternative to expensive automated screening systems.

Main Methods:

• Trace fluorescent labeling of proteins (β-lactoglobulin B, trypsin, Concanavalin A) using Cascade Yellow, Carboxyrhodamine 6G, and Pacific Blue probes.
• Imaging of crystallization plates using smartphones (iPhone 6S) with a 10× macro lens attachment (AUKEY Ora).
• Utilizing LED or laser diodes for excitation and emission filters for fluorescence detection.

Main Results:

• High-quality images of fluorescently labeled protein crystals were obtained using the smartphone-based system.
• The method successfully imaged crystals labeled with different fluorescent probes and two-color fluorescence.
• The cost of the developed system is as low as $50.

Conclusions:

• Smartphone-based macro imaging offers a cost-effective and accessible solution for screening protein crystallization.
• This approach can significantly lower the barrier to entry for structural biology research.
• The technique is adaptable for use with standard microscopy systems for crystal observation.