Solvent molecules significantly affect the supramolecular self-assembly, for example, in forming solvent-bridged hydrogen bonding networks. Even small changes in solvent composition can have dramatic impact on supramolecular assembly. Herein, we demonstrate the use of trace solvents (as low as 0.04%) to tune the morphology and consequent functions of supramolecular nanostructures based on an aromatic peptide bola-amphiphile. Specifically, perylene bisimide-(di)glycine-tyrosine (PBI-[GY]2) bola-amphiphile was shown to give rise to red-emitting nanofibers when assembled in water, while exposure to trace organic solvents such as tetrahydrofuran (THF) and others via solvent-evaporation followed by aqueous assembly gave rise to white-light-emitting nanospheres. Differential hydrogen bonding between water (donor and acceptor) and THF (acceptor only) impacts supramolecular organization, which was verified using a density functional theory (DFT) simulation. The tunable consequent surface hydrophobicity was utilized in staining the cytoplasm and membrane of cells, respectively. The trace-solvent effect achieved through evaporation-dissolution provides a methodology to mediate the morphologies and consequent functions for supramolecular biomaterials controlled by the self-assembly pathway.

OBJECTIVE: Mechanisms for carbon fixation via photosynthesis in the diatom Phaeodactylum tricornutum Bohlin were studied recently but there remains a long-standing debate concerning the occurrence of C4 photosynthesis in this species. A thorough investigation of carbon metabolism and the evidence for C4 photosynthesis based on organelle partitioning was needed.
RESULTS: In this study, we identified the flux ratios between C3 and C4 compounds in P. tricornutum using (13)C-labelling metabolic flux ratio analysis, and stained cells with various cell-permeant fluorescent probes to investigate the likely organelle partitioning required for single-cell C4 photosynthesis. Metabolic flux ratio analysis indicated the C3/C4 exchange ratios were high. Cell staining indicated organelle partitioning required for single-cell C4 photosynthesis might exist in P. tricornutum.
CONCLUSIONS: The results of (13)C-labelling metabolic flux ratio analysis and cell staining suggest single-cell C4 photosynthesis exists in P. tricornutum.
CONCLUSIONS: This study provides insights into photosynthesis patterns of P. tricornutum and the evidence for C4 photosynthesis based on (13)C-labelling metabolic flux ratio analysis and organelle partitioning.