Insulin crystallization: The route from hanging-drop vapour diffusion to controlled crystallization in droplet microfluidics

• Type: Article in International Scientific Journal
• Date: 2022

Authors

Ferreira, J (Author) FEUP; Zsuzsa Sárkány (Author) Other; Filipa Castro (Author) FEUP; Fernando Rocha (Author) FEUP; Simon Kuhn (Author) Other

Journal

Title: Journal of Crystal Growth

Vol. 582

Pages: 1-12

ISSN: 0022-0248

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 0 Citations

Other information

Authenticus ID: P-00W-05R

DOI: 10.1016/j.jcrysgro.2022.126516

Abstract (EN): Although half a century has passed since the mapping of the insulin structure, this globular protein is still currently being investigated. Crystalline drug formulations might replace the subcutaneous injections for diabetes treatment. However, these crystalline forms require carefully tailored properties to sustain controlled release (e.g. longer storage lifetimes and higher purity). Among others, crystal size polydispersity might reduce the speed of insulin release. Here, two distinct crystallization techniques are applied to study insulin crystallization, hanging-drop vapour diffusion and microbatch (droplet microfluidics), and an operating regime map is derived. Rhombohedral insulin crystals with variable size are produced inside the microdroplets for a broad range of insulin concentrations, while aggregate and/or agglomerate formation is observed during the hangingdrop experiments at low protein concentrations. These differences are likely explained by the way acetone evaporation is controlled in each technique. In fact, circular dichroism spectra reveal differences on insulin's secondary structure at variable acetone concentration, including the reduction of alpha-helical content, with no visible beta-sheet-rich structures or random coils. Finally, contrary to what has been reported for other proteins, no temperature effect on insulin crystal size is observed within a range from 10 degrees C to 20 degrees C. This work highlights the formation of insulin crystals in confined microdroplets towards a better control over the insulin crystal size.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12