Manipulation of cross-linking in PEDOT:PSS hydrogels for biointerfacing.

Conducting hydrogels can be used to fabricate bioelectronic devices that are soft for improved cell- and tissue-interfacing. Those based on conjugated polymers, such as poly(3,4-ethylene-dioxythiophene):polystyrene sulfonate (PEDOT:PSS), can be made simply with solution-based processing techniques, yet the influence of fabrication variables on final gel properties is not fully understood. In this study, we investigated if PEDOT:PSS cross-linking could be manipulated by changing the concentration of a gelling agent, ionic liquid, in the hydrogel precursor mixture. Rheology and gelation kinetics of precursor mixtures were investigated, and aqueous stability, swelling, conductivity, stiffness, and cytocompatibility of formed hydrogels were characterized. Increasing ionic liquid concentration was found to increase cross-linking as measured by decreased swelling, decreased non-network fraction, increased stiffness, and increased conductivity. Such manipulation of IL concentration thus afforded control of final gel properties and was utilized in further investigations of biointerfacing. When cross-linked sufficiently, PEDOT:PSS hydrogels were stable in sterile cell culture conditions for at least 28 days. Additionally, hydrogels supported a viable and proliferating population of human dermal fibroblasts for at least two weeks. Collectively, these characterizations of stability and cytocompatibility illustrate that these PEDOT:PSS hydrogels have significant promise for biointerfacing applications that require soft materials for direct interaction with cells.

Where was my patient born? The Intersection of tropical medicine and migrant health.

PURPOSE OF REVIEW: There is unprecedented movement of people across international borders and parasitic infections, previously restricted to endemic regions, are now encountered in nonendemic areas of the world. RECENT FINDINGS: Migrants may import parasitic infections acquired in their countries of origin. Increasingly, clinicians in nonendemic regions are faced with patients with neglected diseases such as Chagas disease, malaria and strongyloidiasis. There are gaps in knowledge among physicians in nonendemic regions, which lead to missed opportunities for preventive strategies and early treatment. Both primary care and infectious disease physicians should have a broad knowledge of common parasitic infections to improve health outcomes and decrease healthcare disparities through early identification and treatment of disease encountered in migrants. SUMMARY: Migrant health is still a young field in medicine; clinicians should be aware of diseases seen in migrants, and access both educational and clinical resources, including experts in tropical medicine, in order to reduce health disparities among migrants. Collaboration between primary care and infectious disease/tropical medicine experts should be strengthened.