Effect of Nanoconfining PLGA Shell on the Self-Assembly of Indigo Carmine

Molecular self-assembly, particularly under 3D spherical confinement, is driven by inherent properties of molecules, as well as the confining system, both play a dominant role in the final self-assembled structure. We recently proposed a novel approach for confinement, in which the core of polymeric nanocapsules was used to entrap organic dye molecules (e.g., indigo carmine), that subsequently organize into rolled up lamellar molecular sheets forming scroll structures. To examine the effect of the confining shell composed by polymeric encapsulating materials, the high molecular weight poly-lactide (PLA) was replaced with low molecular weight poly (lactide-co-glycolide) (PLGA). The PLGA based confining system was prepared by water-in-oil-in-water (W
1
/O/W
2
) double emulsions. Various techniques were used to analyze the physicochemical properties of the self-assembled dye loaded nanocapsules, in terms of particle morphology, size distribution, surface charge, core content, shell composition, loading capacity, and thermal stability. These techniques also served to evaluate the interactions of the dye and its lamellar nanosheets with the interior wall of the capsule shell. The results show, given the same molecular building unit for self-assembling, that the confining shell charge predominates the spatial growth and the direction of assembled organic dye molecules. This provides a further understanding of the polymeric nanocapsule cavities as an emerging viable platform for practical self-assembling applications.