Polysaccharide-Hair Cationic Polypeptide Nanogels: Self-Assembly and Enzymatic Polymerization of Amylose Primer-Modified Cholesteryl Poly(l‑lysine)

In this study, we prepared a new associating polymer, ChMaPLL, by the substitution of the poly­(l-lysine) moiety with oligosaccharide amylose primer and cholesterol. ChMaPLL formed positively charged polypeptide nanogels (∼50 nm) via self-assembly in water. The nanogels showed a secondary structural transition to an α-helix structure induced by poly­(l-lysine) in response to an increase in pH. Oligosaccharides of the nanogels reacted with the phosphorylase a enzyme. Amylose-conjugated nanogels were obtained by enzymatic polymerization. The elongation of the saccharide chain shielded the positive charge of the nanogels. The multiresponsive polysaccharide–polypeptide hybrid nanogels might prove to be useful in the areas of biotechnology and biomedicine

Glyco Star Polymers as Helical Multivalent Host and Biofunctional Nano-Platform

A series of amylose-based star polymers (1, 2, 4, and 8 arms) as a new glyco biomaterial was synthesized by a click reaction and enzymatic polymerization of specific primers with phosphorylase. The molecular weights were controlled by the enzymatic reaction. Further polymerization resulted in a viscous solution and, especially, for the 8-arm primer, a hydrogel was obtained due to effective cross-linking between the multiarmed structures. The star polymers with a degree of polymerization of about 60 per arm acted as an allosteric multivalent host for hydrophobic molecules by helical formation. A cationic 8-arm star polymer catalyzed DNA strand exchange as a nucleic acid chaperone. Amylose-based star polymers are promising building blocks for producing advanced hybrid glyco biomaterials

Long-Lasting and Efficient Tumor Imaging Using a High Relaxivity Polysaccharide Nanogel Magnetic Resonance Imaging Contrast Agent

Clinically approved small-molecule magnetic resonance imaging (MRI) contrast agents are all rapidly cleared from the body and offer weak signal enhancement. To avoid repeated administration of contrast agent and improve signal-to-noise ratios, agents with stronger signal enhancement and better retention in tumors are needed. Therefore, we focused on hydrogels because of their excellent water accessibility and biodegradability. Gadolinium (Gd)-chelating cross-linkers were incorporated into self-assembled pullulan nanogels to both impart magnetic properties and to stabilize this material that has been extensively studied for medical applications. We show that these Gd-chelating pullulan nanogels (Gd-CHPOA) have the highest reported relaxivity for any hydrogel-based particles and accumulate in the 4T1 tumors in mice at high levels 4 h after injection. This combination offers high signal enhancement and lasts up to 7 days to delineate the tumor clearly for longer imaging time scales. Importantly, this long-term accumulation does not cause any damage or toxicity in major organs up to three months after injection. Our work highlights the clinical potential of Gd-CHPOA as a tumor-imaging MRI contrast agent, permitting tumor identification and assessment with a high signal-to-background ratio

Advanced Artificial Extracellular Matrices Using Amphiphilic Nanogel-Cross-Linked Thin Films To Anchor Adhesion Proteins and Cytokines

A novel type of nanogel-cross-linked (NanoClik) film composed of acryloyl-modified cholesterol-bearing pullulan nanogels with pentaerythritol tetra­(mercaptoethyl)­polyoxyethylene as a cross-linker is created through the Michael addition coupled with solvent evaporation. Tensile testing and atomic force microscopy show that the elastic property of the NanoClik films can be controlled by changing the cross-linker concentration. The NanoClik films strongly absorb proteins after simple immersion in solutions of functional proteins, including the hormone insulin, cytokine bone morphogenetic protein-2 (BMP-2), and vitronectin. The amphiphilic nanogels in the films induce this absorption by acting as anchoring and loading proteins. Mouse embryo fibroblast cells adhere to and proliferate on the NanoClik films anchoring vitronectin, while NanoClik films loaded with BMP-2 strongly increase the differentiation of human mesenchymal stem cells into osteoblasts. These results suggest that the NanoClik films act as a novel artificial extracellular matrix that enables the reservation of various biological proteins to the nanogels

TEM imaging of liposomes with ILs and PEG.

<p>After the addition of each [Ch][Lac] and [EMI][Lac] to liposome solutions, and lipids composition and ratio of liposomes were same with FRET and DLS measurements. Samples were put on mesh for EM, and the removal of excess water/sample was carried out. Samples were then set into the TEM. In the case of [Ch][Lac]-liposomes (A), there are various sizes of liposomes between 340−780 nm. In the case of [EMI][Lac]-liposomes (B), liposomes became larger than [Ch][Lac]-liposomes, and the sizes were approximately 1−1.7 μm. Both of the IL-liposomes shapes remained circular. </p

Schematic of the FRET mechanism with respect to vesicle fusion.

<p>(A) When the fluorescent probes NBD-PE and Rho-PE are in a single vesicle, the distance between them is very short, causing fluorescence quenching and no energy transfer. (B) When a probe-labeled vesicle fuses with a non-labeled vesicle, the membrane surface area increases significantly. Thus, the larger distance between NBD-PE and Rho-PE is optimal for fluorescence energy transfer and emission from Rho-PE is observed. Note that the fusion of non-labeled vesicles is not undetected. Furthermore, if labeled lipid vesicles fuse, emission depends on the distances between the NBD-PE and Rho-PE probes. </p

Self-Assembled pH-Sensitive Cholesteryl Pullulan Nanogel As a Protein Delivery Vehicle

A self-assembled nanogel, derived from an acid-labile cholesteryl-modified pullulan (acL-CHP), was prepared by grafting vinyl ether-cholesterol substituents onto a 100 kD pullulan main chain polymer backbone. Stable nanogels are formed by acL-CHP self-assemblies at neutral pH. The hydrodynamic radius of the nanogels, observed to be 26.5 ± 5.1 nm at pH 7.0, increased by ∼135% upon acidification of the solution to pH 4.0. SEC analysis of the acL-CHP nanogel at pH 4.0 showed that the grafts were nearly 80% degraded after 24 h, whereas little or no degradation was observed over the same time period for a pH stable analog (acS-CHP) at pH 4.0 or the acL-CHP at pH 7.0. Complexation of BSA with the acL-CHP nanogel was observed at pH 7.0 with subsequent release of the protein upon acidification. These findings suggest that stimuli-responsive, self-assembled nanogels can release protein cargo in a manner that is controlled by the degradation rate of the cholesterol-pullulan grafting moiety

Saccharide Recognition Based on Self-Assembly of Amphiphilic Phenylboronic Acid Azoprobes

We designed amphiphilic phenylboronic acid azoprobes (<b>B-Azo-Cn</b>) and evaluated their saccharide recognition function in relation to the micelle formation changes of the self-assembled <b>B-Azo-Cn</b>. First, we evaluated <b>B-Azo-C8</b> in a 1% methanol–99% water solution under basic conditions. The wavelength of maximum absorption in the ultraviolet–visible (UV–vis) spectra of <b>B-Azo-C8</b> was shifted, and the solution showed a color change with the addition of saccharides. The morphology of <b>B-Azo-C8</b> was evaluated using dynamic light scattering (DLS) measurements and transmission electron microscopy (TEM) observations. <b>B-Azo-C8</b> formed aggregates in the absence of saccharides and in the presence of glucose. In the presence of fructose, micelle-formed <b>B-Azo-C8</b> was dispersed, indicating that <b>B-Azo-C8</b> changed its dispersion state by recognizing fructose. The effect of alkyl chain length on the saccharide recognition ability was examined as well. <b>B-Azo-C4</b> and <b>B-Azo-C12</b> did not recognize saccharides in a 1% methanol–99% water solution under basic conditions, indicating that an appropriate alkyl chain length was required for recognizing saccharides. The control of the hydrophilic–lipophilic balance (HLB) was a key factor for saccharide recognition

Effect of ILs on the FRET ratio for DOPC-SM-Chol bilayer vesicles.

<p>[EMI][Lac] and [Ch][Lac] were used at 10% (A), 20% (B) and 30% (v/v) (C). For the 20% and 30% concentrations, [EMI][Lac] (black line) shows a higher ability to induce membrane fusion than [Ch][Lac] (red line). However, there were no distinct differences between [EMI][Lac] and [Ch][Lac] at a concentration of 10% (v/v) (A). (D) Shows the maximum FRET fluorescence intensity changes (normalized) as a function of [EMI][Lac] and [Ch][Lac] concentrations. At 30%-[EMI][Lac] (black square), the ratio of membrane fusion ability was ≈1.4 times higher than that of [Ch][Lac] (red square) at the same concentration. </p

Comparison of the vesicle diameters at various concentration of [Ch][Lac] and [EMI][Lac].

<p>Comparison of the vesicle sizes between control vesicles and the presence of 30%-[EMI][Lac] or [Ch][Lac] (see Supporting Data). For both ILs, peak sizes became larger with increasing IL concentration. </p