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ABSTRACT: New hybrid poly(ethylene glycol) (PEG) hydrogels crosslinked with both nanogels and nanogel-coated liposome complexes are obtained by Michael addition of the acryloyl group of a cholesterol-bearing pullulan (CHP) nanogel to the thiol group of pentaerythritol tetra(mercaptoethyl) polyoxyethylene. The nanogel-coated liposome complex is stably retained after gelation and the complexes are well dispersed in the hybrid gel. Microrheological measurements show that the strength and gelation time of the hybrid hydrogel can be controlled by changing the liposome:nanogel ratio. The hydrogel is gradually degraded by hydrolysis under physiological conditions. In this process, the nanogel is released first, followed by the nanogel-coated liposomes. Hybrid hydrogels that can incorporate various molecules into the nanogel and liposomes, and release them in a two-step controllable manner, represent a new functional scaffold capable of delivering multiple drugs, proteins or DNA.
Advanced healthcare materials. 11/2012; 1(6):722-8.
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ABSTRACT: An azobenzene-modified cholesterol was designed and synthesized for photo-induced domain transformation in lipid bilayer membranes.
Upon UV-light irradiation, the cholesterol derivative changes the conformation through photoisomerization of the azobenzene
moiety from trans- to cis-form. The photoisomerization effectively occurred both in liquid-ordered (Lo) and liquid-disordered (Ld) phases. Phase-contrast and fluorescence microscopic observation revealed that photoisomerization of the azobenzene-modified
cholesterol induced the shape transformation of giant unilamellar vesicle (GUV) and the reorganization of Lo domain structure. Such a photo-induced transformation of lipid domain gave two different pathways dependent on the lipid
composition of GUV; disappearance of the Lo domain or appearance of a small Ld domain with in the Lo domain.
Colloid and Polymer Science 04/2012; 286(14):1675-1680. · 2.33 Impact Factor
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ABSTRACT: The thermal stabilization and refolding of horseradish peroxidase (HRP) upon heating were investigated using an artificial
molecular chaperone consisting of cholesterol-bearing pullulan (CHP) nanogels. The CHP nanogels inhibited the aggregation
of HRP under heating by complexation with the denatured HRP. The enzyme activity of HRP complexed with CHP nanogels was not
detected. However, the enzyme activity recovered up to 80% of native HRP after the addition of cyclodextrin (CD) to the complex.
The dissociation of CHP nanogels was induced by the formation of an inclusion complex of cholesterol groups of CHP with CD.
The enzyme activity of HRP was only significantly recovered by the addition of β-CD or its derivatives. Natural molecular
chaperones, such as GroEL/ES, trap, fold, and release the nonnative proteins by changing the hydrophobicity of the specific
sites of the molecular chaperone that interact with the nonnative protein. The functional mechanism of the nanogel chaperon
system is similar to that of natural molecular chaperones. The nanogel chaperone system is a useful tool to aid the refolding
and thermal stabilization of unstable proteins for post-genome research, and in medical and biological applications.
KeywordsArtificial chaperone–Protein refolding–Nanogel–Hydrophobic interaction–Cyclodextrin
Colloid and Polymer Science 04/2012; 289(5):685-691. · 2.33 Impact Factor
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ABSTRACT: A supramolecular system that can activate an enzyme through photo-isomerization was constructed by using a liposomal membrane scaffold. The design of the system was inspired by natural signal transduction systems, in which enzymes amplify external signals to control signal transduction pathways. The liposomal membrane, which provided a scaffold for the system, was prepared by self-assembly of a photoresponsive receptor and a cationic synthetic lipid. NADH-dependent L-lactate dehydrogenase, the signal amplifier, was immobilized on the liposomal surface by electrostatic interactions. Recognition of photonic signals by the membrane-bound receptor induced photo-isomerization, which significantly altered the receptor's metal-binding affinity. The response to the photonic signal was transmitted to the enzyme by Cu(2+) ions. The enzyme amplified the chemical information through a catalytic reaction to generate the intended output signal.
Chemistry 03/2012; 18(11):3258-63. · 5.93 Impact Factor
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ABSTRACT: A nanosensory membrane device was constructed for detecting liposome fusion through changes in an enzymatic activity. Inspired by a biological signal transduction system, the device design involved functionalized liposomal membranes prepared by self-assembly of the following molecular components: a synthetic peptide lipid and a phospholipid as matrix membrane components, a Schiff's base of pyridoxal 5'-phosphate with phosphatidylethanolamine as a thermo-responsive artificial receptor, NADH-dependent L-lactate dehydrogenase as a signal amplifier, and Cu(2+) ion as a signal mediator between the receptor and enzyme. The enzymatic activity of the membrane device was adjustable by changing the matrix lipid composition, reflecting the thermotropic phase transition behavior of the lipid membranes, which in turn controlled receptor binding affinity toward the enzyme-inhibiting mediator species. When an effective fusogen anionic polymer was added to these cationic liposomes, membrane fusion occurred, and the functionalized liposomal membranes responded with changes in enzymatic activity, thus serving as an effective nanosensory device for liposome fusion detection.
Sensors 01/2012; 12(5):5966-77. · 1.74 Impact Factor
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ABSTRACT: Molecular chaperones selectively trap heat-denatured proteins or their intermediates, primarily by hydrophobic interactions, to prevent irreversible aggregation resulting from macromolecular host (molecular chaperone)-guest (protein) interactions. The molecular chaperone function is an important concept that is expected to lead to breakthroughs in drug delivery systems, especially for protein or peptide delivery in regenerative medicine, such as bone regeneration. We have reported that polysaccharide nanogels act as artificial molecular chaperones. To further clarify the molecular chaperone function of nanogels as protein carriers, the elucidation of nanogel-protein interactions are especially important. Here, we investigated the interaction of a protein with a polysaccharide nanogel using fluorescence correlation spectroscopy at variable temperatures, using fluorescence-labeled bovine serum albumin (BSA) as a model protein. In particular, thermodynamic parameters of the heat-induced complexation of protein with CHP nanogels were evaluated using the van't Hoff plot. The plot shows that the CHP nanogels strongly complexed with heat-denatured BSA. The increased hydrophobicity of the denatured, unfolded protein may prefer complexation with amphiphilic hydrogel nanoparticles over complexation with the completely folded native protein. Thermodynamic parameters suggest that the complexation is entropically driven, rather than enthalpically, under the conditions studied.
Current Drug Discovery Technologies 06/2011; 8(4):308-13.
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ABSTRACT: Cell-free protein synthesis is a promising technique for the rapid production of proteins. However, the application of the cell-free systems requires the development of an artificial chaperone that prevents aggregation of the protein and supports its correct folding. Here, nanogel-based artificial chaperones are introduced that improve the folding efficiency of rhodanese produced in cell-free systems. Although rhodanese suffers from rapid aggregation, rhodanese was successfully expressed in the presence of the nanogel and folded to the enzymatically active form after addition of cyclodextrin. To validate the general applicability, the cell-free synthesis of ten water-soluble proteins was examined. It is concluded that the nanogel enables efficient expression of proteins with strong aggregation tendency.
Macromolecular Bioscience 03/2011; 11(6):814-20. · 3.89 Impact Factor
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ABSTRACT: Molecular communication is a novel communication paradigm inspired by information processing in biological systems using molecules as information medium. In this study, we achieved the selective propagation of transport vesicles which is an essential technique to establish a molecular communication system using artificial cells. The hybridisation of DNA was employed to conduct a signal-induced delivery of transport vesicles from a sender to a receiver vesicle formed with phospholipids. Oligonucleotide lipids each with a different single-stranded DNA, which acts as recognition tags, were embedded in the sender, receiver and transport vesicles. The addition of a DNA signal with a complementary sequence to connect two oligonucleotide lipids induced the assembly of two types of large unilamellar vesicles as well as recombination of the vesicles. In addition, the selective delivery of transport vesicles between sender and receiver giant vesicles is discussed, based on the results of fluorescence microscopic observations.
Supramolecular Chemistry. 03/2011; 23(3–4):218-225.
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ABSTRACT: We constructed a supramolecular system on a liposomal membrane that is capable of activating an enzyme via DNA hybridization. The design of the system was inspired by natural signal transduction systems, in which enzymes amplify external signals to control signal transduction pathways. The liposomal membrane, providing a platform for the system, was prepared by the self-assembly of an oligonucleotide lipid, a phospholipid and a cationic synthetic lipid. The enzyme was immobilized on the liposomal surface through electrostatic interactions. Selective recognition of DNA signals was achieved by hybridizing the DNA signals with the oligonucleotide lipid embedded in the liposome. The hybridized DNA signal was sent to the enzyme by a copper ion acting as a mediator species. The enzyme then amplified the event by the catalytic reaction to generate the output signal. In addition, our system demonstrated potential for the discrimination of single nucleotide polymorphisms.
Organic & Biomolecular Chemistry 02/2011; 9(7):2397-402. · 3.70 Impact Factor
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ABSTRACT: Nanosize hydrogels (nanogels) are polymer nanoparticles with three-dimensional networks, formed by chemical and/or physical cross-linking of polymer chains. Recently, various nanogels have been designed, with a particular focus on biomedical applications. In this review, we describe recent progress in the synthesis of nanogels and nanogel-integrated hydrogels (nanogel cross-linked gels) for drug-delivery systems (DDS), regenerative medicine, and bioimaging. We also discuss chaperone-like functions of physical cross-linking nanogel (chaperoning engineering) and organic-inorganic hybrid nanogels.
The Chemical Record 12/2010; 10(6):366-76. · 4.38 Impact Factor
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ABSTRACT: Molecular chaperones in living systems inspired us to explore new concepts for assisting protein refolding. The chaperone selectively interacts with a non-native protein by hydrophobic interaction to prevent irreversible aggregation and releases the protein in its refolded form with the aid of ATP and another co-chaperone. Cyclodextrins have been used to simulate the function of the chaperones by controlling the hydrophobic interaction with proteins. In this chapter, we review the cyclodextrin (CD)-related protein refolding systems.
Current pharmaceutical biotechnology 02/2010; 11(3):300-5. · 3.40 Impact Factor
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ABSTRACT: This paper describes construction of a nanosensory device for amplified detection of biologically important amines as chemical signals. The device was inspired by a biological signal transduction system, and was fabricated on an artificial cell membrane through self-organization of the molecular components, such as a synthetic receptor and a natural enzyme. Selective recognition of biologically important amines was achieved by a synthetic receptor with a pyridoxal moiety, as evaluated by means of electronic absorption spectroscopy. The selectivity in detecting amines as chemical signals mainly depends on hydrophobicity of the amines. The event upon detecting the chemical signals was transmitted to an enzyme by a metal ion acting as a mediator species, and then the enzyme amplified the event by the catalytic reaction to obtain signal output. This paper is realization of a biomimetic signal transduction system using amines as chemical signals and may provide a useful guidepost for designing integrated nanosystems.
Biotechnology and Bioengineering 10/2009; 105(1):37-43. · 3.95 Impact Factor
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Supramolecular Chemistry. 04/2009;
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ABSTRACT: Molecular communication is a bio-inspired communication paradigm using molecules as information carriers. The molecular communication system includes propagation of information carrier molecules between a molecular sender and a molecular receiver and followed by amplification of the information at the receiver. In this article, we built an example molecular communication system using a gemini peptide lipid as a molecular switch. The molecular switch embedded in the lipid bilayer membranes exhibited photoresponsive recognition behaviour towards metal ions, such as Cu2+ and Zn2+, to control propagation of molecular capsules formed by small liposomes to a giant liposomal receiver. In addition, the molecular switch acted as an artificial receptor in the receiver, receiving a photonic signal to communicate with an enzyme as a signal amplifier by using Cu2+ ion as a mediator between the receptor and the amplifier.
Supramolecular Chemistry. 04/2009; 21(Nos. 3–4):284-291.
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BIONETICS '08 Proceedings of the 3rd International Conference on Bio-Inspired Models of Network, Information and Computing Sytems, Hyogo, Japan; 11/2008
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ABSTRACT: A novel fluorescent sensor responsive to local viscosity in the lipid bilayer membranes was designed and synthesized. The sensor changes its fluorescence intensity reflecting the local viscosity of its surrounding medium. The fluorescence measurement showed that the sensor is capable of discriminating between different phase states of lipid bilayer. In addition, the sensor visualized liquid-ordered microdomains on giant vesicles in terms of the microviscosity with a simple fluorescence technique.
Colloids and Surfaces B Biointerfaces 09/2008; 67(1):145-9. · 3.46 Impact Factor
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ABSTRACT: Colloidal gold nanorods (GNRs), which were passivated with cationic cerasome-forming lipids having triethoxysilyl groups, were obtained in the aqueous phase by sonication of the mixture of lipids and GNRs.
Chemical Communications 10/2007; · 6.17 Impact Factor
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ABSTRACT: Surface-rigidified cerasomes (ceramic-coated liposomes) are neither fused nor cross-linked when bound to siRNA (short duplex RNA) but not to plasmid DNA (long duplex DNA) which induces cross-linking. Non-ceramic reference liposomes are easily fused by the siRNA. The cerasome can thus be used as a viral-size siRNA-carrier in a wide range of concentration for RNAi silencing of exogenous and endogenous genes.
Bioorganic & Medicinal Chemistry Letters 08/2007; 17(14):3935-8. · 2.55 Impact Factor
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ABSTRACT: Alanine-based cationic lipid 1 having a (EtO)3SiCH2CH2CH2 group on the quaternized ammonium nitrogen forms a liposome which self-rigidifies via in situ sol-gel processes (Si-OEt + H2O --> Si-OH + EtOH followed by 2Si-OH --> Si-O-Si + H2O) on the surface. The resulting cerasome (partially ceramic- or silica-coated liposome) (60-70 nm) retains the integrity of such in the complexation with lucifarase-encoding plasmid DNA pGL3. The resultant pGL3 complex of infusible or monomeric cerasome in a viral size ( approximately 70 nm) exhibits a remarkable transfection performance toward HeLa and HepG2 cells with a 102-3-fold higher efficiency (relative to that of the nonsilylated reference lipid 2), minimized cytotoxicity, and serum compatibility. Reference lipid 2, i.e., alanine-based lipid having a simple quaternized ammonium headgroup, forms liposome (60-70 nm) which is less self-confined and more mobile undergoes DNA-induced fusion to give endocytosis-irrelevant and more toxic bigger (100-300 nm) particles. The silicon strategy thus provides a simple and widely applicable tool to overcome general problems associated with current technology of artificial gene delivery.
Journal of the American Chemical Society 03/2006; 128(10):3114-5. · 9.91 Impact Factor
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ABSTRACT: A new molecular design of fullerene derivatives exhibiting trigger-responsive self-aggregation in organic solvents has been established. Calix[4]arene was covalently connected with fullerene in order to apply host-guest interaction to the aggregation control. The self-assembly behaviour was studied in organic solvents by UV-vis absorption spectroscopy, dynamic light scattering and transmission electron microscopy. Results show that the bisfullerene formed self-aggregations with a low polydispersity index due to the fullerenes' tendency to aggregate in polar organic solvents. Furthermore, the aggregate sizes can be changed readily by solvent composition and the addition of guest cations. Especially, disaggregation of the bisfullerene was induced by addition of LiClO4 or NaClO4.
Organic & Biomolecular Chemistry 03/2006; 4(3):519-23. · 3.70 Impact Factor
