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HBDI-like chromophores represent a novel set of biomimetic switches mimicking the fluorophore of the green fluorescent protein that are currently studied with the hope to expand the molecular switch/motor toolbox. However, until now members capable of absorbing visible light in their neutral (i. e. non-anionic) form have not been reported. In this contribution we report the preparation of an HBDI-like chromophore based on a 3-phenylbenzofulvene scaffold capable of absorbing blue light and photoisomerizing on the picosecond timescale. More specifically, we show that double-bond photoisomerization occurs in both the E-to-Z and Z-to-E directions and that these can be controlled by irradiating with blue and UV light, respectively. Finally, as a preliminary applicative result, we report the incorporation of the chromophore in an amphiphilic molecule and demonstrate the formation of a visible-light-sensitive nanoaggregated state in water.

Sulfavant A (1) and Sulfavant R (2) are amphiphilic sulfoquinovoside-glycerol lipids under study as molecular adjuvants of vaccines. Their structures differ only for the configuration of the oxymethine carbon of glycerol that is R/S in 1 and R in 2. The in vitro activity of both products follows a bell-shaped dose-response curve but 1 gave the best response between 10 and 30 µM, while 2 was active at 10 nM. Characterization of aqueous self-assembly of these molecules by a multi-technique approach based on surface tensiometry, dynamic light scattering (DLS), nuclear magnetic resonance (NMR), fluorescence light phase contrast, and cryo-electron microscopy has finally clarified this divergent and controversial biological outcome. The study proved the occurrence of supramolecular structures at concentrations much lower than the critical aggregation concentration (CAC) calculated by surface tensiometry for both products. The shape and size of these aggregates varied as a function of the concentrations differently for 1 and 2. At nanomolar concentration, Sulfavant A (1) formed cohesive vesicular structures, while Sulfavant R (2) arranged in small spherical micellar particles whose reduced stability was responsible for an increase of the monomer concentration that well agreed with the immunomodulatory activity. On the other side, micromolar concentrations led to an increase of particle sizes of both compounds and a transition from micellar to the vesicular state of Sulfavant R (2). The thermodynamic stability of these aggregates correlated with the activity of 1 above 10 µM and the complete loss of efficacy of 2 at micromolar concentrations. The study of Sulfavants provides clear evidence of how self-aggregation and thus the equilibria between the monomers and the supramolecular forms of lipophilic products in aqueous media determine the overall response of these substances in cell-based assays.

Water-soluble MBHA derivatives were found to self-assemble in a water environment to generate aggregates showing core–shell architectures. The aggregates appeared to be capable of working as nanoreactors performing a multi-functionalization of poly-histidine fragments, which after an initial interaction with the solvated oligo(ethylene glycol) shell reach the reactive core.

The technique of grafting side chains onto a linear polymeric backbone is commonly used to confer to the new polymeric material with desired properties, such as tunable solubility, ionic charge, biocompatibility, or specific interactions with biological systems. In this paper, two new polybenzofulvene backbones were assembled by spontaneous polymerization of the appropriate benzofulvene monomers (4,6-PO-BF3k and 4&rsquo, 6-PO-BF3k) bearing two clickable propargyloxy groups in different positions of the 3-phenylindene scaffold. Poly-4,6-PO-BF3k and poly-4&rsquo, 6-PO-BF3k were grafted with monomethyl oligo(ethylene glycol) (MOEG) to prepare two new polybenzofulvene brushes (i.e., poly-4,6-MOEG-9-TM-BF3k and poly-4&rsquo, 6-MOEG-9-TM-BF3k) by means of a &ldquo, grafting onto&rdquo, approach, that were characterized from the point of view of their macromolecular features, aggregation liability, and in a preliminary evaluation of biocompatibility. The obtained results make these PEGylated polybenzofulvene brushes (PPBFB) derivatives potentially useful as nanocarriers for nanoencapsulation and delivery of drug molecules.