Interfacing manganese-based carbonaceous nanocomposites with plasma components: insights on protein interaction, structure and opsonization.

Metal encapsulation delivers a straightforward strategy to improve miscellaneous nanoparticle properties and qualifies the resulting nanocomposite for exceptional application, including bioimaging, drug release, and theranostic development. Besides crucial applications, investigations associated with the nanocomposite impact on the biological media are highly relevant from a pharmacological viewpoint. Such studies can be conducted by exploring nanocomposite attributes and all aspects of their interaction with proteins existing in biofluids. Based on these aspects, the present work examines manganese-encapsulated carbonaceous nanocomposite (MnCQD) and their interaction with plasma proteins. On one side, the obtained nanocomposite has almost spherical shapes (12 nm in size), an appropriate composition and interesting optical properties for bioimaging applications. On another side, MnCQD quenches the fluorescence of two plasma proteins (BSA and HTF) following a static mechanism, confirming the formation of the MnCQD-BSA and MnCQD-HTF complexes. Although hydrophobic forces guide the stability of both formed complexes, MnCQD binds preferentially to BSA compared to HTF, with affinity constants differing by almost an order of magnitude. Furthermore, HTF and BSA underwent modifications in their secondary structure provoked due to contact with the nanocomposite, which also presented neglectable opsonization levels when exposed to appropriate biological media. These results highlight the MnCQD outstanding potential to be employed in diverse bioapplications.Communicated by Ramaswamy H. Sarma.