Using a Kinase/Phosphatase Switch to Regulate a Supramolecular Hydrogel and Forming the Supramolecular Hydrogel in Vivo

We have designed and synthesized a new hydrogelator Nap−FFGEY (1), which forms a supramolecular hydrogel. A kinase/phosphatase switch is used to control the phosphorylation and dephosphorylation of the hydrogelator and to regulate the formation of supramolecular hydrogels. Adding a kinase to the hydrogel induces a gel−sol phase transition in the presence of adenosine triphosphates (ATP) because the tyrosine residue is converted into tyrosine phosphate by the kinase to give a more hydrophilic molecule of Nap−FFGEY−P(O)(OH)2 (2); treating the resulting solution with a phosphatase transforms 2 back to 1 and restores the hydrogel. Electron micrographs of the hydrogels indicate that 1 self-assembles into nanofibers. Subcutaneous injection of 2 in mice shows that 80.5 ± 1.2% of 2 turns into 1 and results in the formation of the supramolecular hydrogel of 1 in vivo. This simple biomimetic approach for regulating the states of supramolecular hydrogels promises a new way to design and construct biomaterials

Supramolecular Hydrogels Respond to Ligand−Receptor Interaction

N-(Fluorenyl-9-Methoxycarbonyl) dipeptides form supramolecular hydrogels via hydrogen bonding and hydrophobic interactions. These hydrogels respond to a ligand−receptor interaction as well as to thermal or pH perturbation and also exhibit chiral recognition

Glutathione-Triggered Formation of a Fmoc-Protected Short Peptide-Based Supramolecular Hydrogel

<div><p>A biocompatible method of glutathione (GSH) catalyzed disulfide bond reduction was used to form Fmoc-short peptide-based supramolecular hydrogels. The hydrogels could form in both buffer solution and cell culture medium containing 10% of Fetal Bovine Serum (FBS) within minutes. The hydrogel was characterized by rheology, transmission electron microscopy, and fluorescence emission spectra. Their potential in three dimensional (3D) cell culture was evaluated and the results indicated that the gel with a low concentration of the peptide (0.1 wt%) was suitable for 3D cell culture of 3T3 cells. This study provides an alternative candidate of supramolecular hydrogel for 3D cell culture and cell delivery.</p></div

Development of a DPAP1-specific HTS assay.

<p><b>A.</b> Continuous assay. The assay was carried out in 384-well plates using 1% of parasite lysates. Substrate turnover was continuously measured for 5 min. JCP410 (10 µM) was used as a positive inhibition control. Z’ factor, S/N, and % CV of the negative control are shown. <b>B.</b> End-point assay for HTS. The reaction described in A was quenched after 10 min by addition of 0.5 M acetic acid. The final concentration of rhodamine product was quantified by fluorescence.</p

Cell proliferation rate of 3T3 cells in gels at different concentrations determined by the CCK-8 assay.

<p>Cell proliferation rate of 3T3 cells in gels at different concentrations determined by the CCK-8 assay.</p

Use of an ABP to identify a DPAP1-selective substrate in parasite lysates.

<p><b>A.</b> Structure and reaction mechanism of the (Pro-Arg)₂-Rho substrate. <b>B.</b> Measurement of (Pro-Arg)₂-Rho apparent <i>K</i>_m in trophozoite lysates (circles) and with recombinant DPAP1 (triangle). Turnover rates at increasing concentrations of substrate were fitted to a Michaelis-Menten equation as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011985#s4" target="_blank">methods</a> section. <b>C.</b> Labeling of DPAP1 activity in parasite lysates with FY01. Trophozoite lysates were incubated for 1 h with increasing concentrations of FY01. Labeling was stopped by boiling the sample in SDS-PAGE loading buffer. DPAP1 activity was measured using a flatbed fluorescent scanner. <b>D.</b> DPAP1 labeling correlates with substrate turnover inhibition. An aliquot of the samples treated for 1 h with FY01 was diluted in assay buffer containing 10 µM of (Pro-Arg)₂-Rho, and the initial turnover rate was measured in a 96-well plate (circles). This turnover rate is plotted with the labeling quantified in C.</p

Facet-Selective 2D Self-Assembly of TiO₂ Nanoleaves via Supramolecular Interactions

Using catechol-group-terminated Zn(II)−porphyrin (ZnP) to functionalize the single-crystalline TiO2 nanoleaves and coordinate ZnP with trans-2,2′-ethylene 4, 4′-bipyridyl (1), we demonstrate the self-assembly of TiO2 nanoleaves based on a supramolecular interaction. Compound 1 cross-links the adjacent TiO2 nanoleaves along the [101] face, results in a facet-selective, self-assembled, 2D stacking structure. This observation suggests that supramolecular interactions offer a promising route to control anisotropic nanomaterials into designed geometry

A cryo-transmission electron microscopy (cryo-TEM) image of the gel from a PBS solution containing 0.3 wt% of the pro-gelator with 4 equiv. of GSH.

<p>A cryo-transmission electron microscopy (cryo-TEM) image of the gel from a PBS solution containing 0.3 wt% of the pro-gelator with 4 equiv. of GSH.</p

Heterodimers of Nanoparticles: Formation at a Liquid−Liquid Interface and Particle-Specific Surface Modification by Functional Molecules

On the basis of a fundamental property of nanoparticles, the self-assembling at a liquid−liquid interface to form “colloidosomes”, a heterogeneous reaction takes place on the exposed surface of the nanoparticles to produce the heterodimers of two distinct nanospheres, which can be modified by two different functional molecules in a particle-specific manner

Optical images of cells at day 5 in gels at A) 0.3 wt%, B) 0.2 wt%, and C) 0.1 wt% (scale bars represent 10 µm).

<p>Optical images of cells at day 5 in gels at A) 0.3 wt%, B) 0.2 wt%, and C) 0.1 wt% (scale bars represent 10 µm).</p