Photoresponsive Nanogels Formed by the Self-Assembly of Spiropyrane-Bearing Pullulan That Act as Artificial Molecular Chaperones

Hirakura, Tai; Nomura, Yuta; Aoyama, Yasuhiro; Akiyoshi, Kazunari

doi:10.1021/bm049860o

Cited by 113 publications

(85 citation statements)

References 35 publications

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“…[15][16][17][18] The hydrogel NPs can also be used as a drug carrier system in medicine 17,19,20 as well as artificial molecular chaperones in biotechnology. [21][22][23] On the basis of these, our group developed a new method to synthesize cholesterol-modified pullulan (CHSP) by directly grafting proper cholesterol residues onto pullulan using succinyl linkages, thus providing a new strategy for the effective and safe synthesis of CHSP. In vitro studies indicated that CHSP self-assembled NPs showed potential as a sustained-release carrier of mitoxantrone.…”

Section: Introductionmentioning

confidence: 99%

Cellular uptake mechanism and intracellular fate of hydrophobically modified pullulan nanoparticles

Jiang¹,

Li²,

Liu³

et al. 2013

IJN

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Abstract:The cellular uptake mechanism and intracellular fate of self-assembled nanoparticles (NPs) of cholesterol-modified pullulan (CHSP) by human hepatocellular carcinoma (HepG2) cells were investigated. Covalent conjugation with fluorescein isothiocyanate (FITC) yielded stably labeled CHSP (FITC-CHSP), which was successfully formulated into NPs (mean particle size 63.0 ± 1.9 nm) by dialysis. A cytotoxicity assay clearly indicated that the CHSP NPs did not show significant toxicity in HepG2 cells. The effects of NP concentration, incubation time, and temperature on the cellular uptake of the NPs were systematically evaluated by fluorometry, and the results suggested that cellular uptake of the NPs was concentration-, time-, and temperature-dependent. In vitro experiments with endocytic inhibitors revealed that clathrin-mediated endocytosis and macropinocytosis were involved in the internalization of CHSP NPs. The intracellular trafficking study demonstrated that CHSP NPs were entrapped in the lysosomes at 1 hour after incubation; colocalization of NPs with either the Golgi apparatus or the endoplasmic reticula was not observed during the entire course of the study. These results suggested that the CHSP NPs may serve as a versatile carrier for intracellular delivery of therapeutic agents.

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Section: Introductionmentioning

confidence: 99%

Cellular uptake mechanism and intracellular fate of hydrophobically modified pullulan nanoparticles

Jiang¹,

Li²,

Liu³

et al. 2013

IJN

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“…194 The physical crosslinks are formed by the aggregation of hydrophobic spiropyran groups. In analogy to the example described above, these molecules are known to undergo a light-triggered change in configuration to a hydrophilic zwitter-ionic merocyanine form, thereby reducing the hydrophobic interactions, destroying the physical crosslinking points and changing the solution properties of the microgels.…”

Section: Microgels Containing Photo-degradable Crosslinkersmentioning

confidence: 99%

Light-Sensitive Polymeric Nanoparticles Based on Photo-Cleavable Chromophores

Klinger

2013

Springer Theses

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This thesis focuses on the design, synthesis and characterization of novel photo-sensitive microgels and nanoparticles as potential materials for the loading and light-triggered release/accessibility of functional compounds. In order to realize this concept, different approaches to irradiation-dependent response mechanisms have been investigated.Novel light-cleavable divinyl functionalized monomeric crosslinkers based on o-nitrobenzyl derivatives were synthesized and used for the preparation of either PMMA or hydroxyl functionalized PHEMA microgels swellable and degradable in organic solvents. By the introduction of anionic MAA moieties into the PHEMA microgels, this concept was successfully transferred to double stimuli-responsive p(HEMA-co-MAA) hydrogel nanoparticles exhibiting a pH-dependent swelling and light-induced degradation behavior in aqueous media. This sensitivity to two orthogonal triggers is proposed to combine a pHinduced post-formation loading mechanism with a pH-and light-triggered release. In addition, a new class of enzyme-and light-sensitive PAAm microgels based on (meth-)acrylate functionalized dextrans as photo-and enzymatically degradable macromolecular crosslinkers was developed by introducing a photo-labile linker between the enzymatically degradable dextran chain and the polymerizable vinyl moieties. Here, the water solubility of the crosslinkers is assumed to enable an in situ loading approach of hydrophilic compounds.A different approach to the loading of microgels is based on photo-labile covalent microgel-drug conjugates. The first step to the realization of this concept was achieved by the development of a novel functional monomer consisting of a doxorubicin molecule covalently attached to a radically polymerizable methacrylate group via a photo-cleavable linker.Moreover, in order to enable the release of hydrophobic substances in aqueous media, hydrophobic nanoparticles consisting of a photo-resist polymer were designed to be degradable upon irradiation in water. Light-triggered conversion of the initial hydrophobic polymer into hydrophilic PMAA induced in situ particle dissolution and release of nile red.Since the introduction of a stimuli-responsive shell around a microgel is assumed to prevent leakage of embedded compounds, studies on non-stimuli-responsive shell formation around preformed microgel seed particles and the formation of microgel cores in polymeric shells were conducted to investigate potential synthetic pathways to this approach.In a last attempt, the surface of PHEMA and p(HEMA-co-MAA) microgels was functionalized with cinnamoyl groups in order to trigger the (reversible) particles interaction with each other by light-induced [2+2] cycloaddition reactions.

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“…One of the characteristic features of spiropyrans is a strong absorption, maximum around the 290-380 nm regions due to the presence of benzopyran moiety. A number of attempts to incorporate spiropyran molecules into polymer systems have been reported, which include photochromic studies of spiropyrans in polymer matrices [62], liquid crystal polymers containing spiropyran as mesophases [63], and spiropyran-grafted dextran [64], pullulan [65], polydimethylsiloxane [66], and other synthetic polymers [67]. Selected examples are illustrated in Figure 9.6.…”

Section: Spiropyransmentioning

confidence: 99%

Photochromic Responses in Polymer Matrices

Ramachandran

Urban

2011

Handbook of Stimuli‐Responsive Materials

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IntroductionMany concepts of photochromic systems have been inspired by nature. An illustrative example is the reversible shape changes of the photoreceptor molecule rhodopsin in eyes that produces a cascade of molecular rearrangements responding to light illumination [1]. Upon photoexcitation, all-trans retinal undergoes isomerization to 11-cis across the double bond, thus causing shape changes. Although this event occurs at the angstrom (Å) level, there are many molecular interconnected events and responses that are not fully understood. Similar processes have been observed in certain molecules in materials chemistry, although on a much smaller and at a less-orchestrated scale. These are known as photochromic molecules, which were discovered over 150 years ago in an organic crystal of tetracene, and later on, in inorganic and organometallic materials [2][3][4]. In spite of a long research history, a quest for new photochromic materials continues. Color changes induced by ultraviolet (UV) radiation caused by trans − − cis isomerization, ring opening-closing reactions, inter-or intramolecular charge transfer, or bimolecular cycloaddition reactions are of particular interest. To make use of their photochromic behavior in various applications, photochromic entities are often incorporated into polymer matrices.While creating individual molecules and understanding their electronic properties facilitated further advances in understanding molecular mechanisms governing photochromism, useful applications require fabrication into films, sheets, fibers, or beads. This is typically achieved by incorporating photochromic molecules into macromolecular matrices by doping or dispersing, or covalently attaching them onto a polymer backbone. Since photoisomerization of chromophores alter equilibrium conformations, the dimensions of the surrounding polymer matrix play an essential role in spatial rearrangements. The dimensional classifications of the matrix effect have been extensively examined [5], with notable applications in ophthalmic lens, optical storage media, photosensors, and biomedical devices. Furthermore, the kinetics of conformational changes of polymers with photochromic moieties depends upon their physical or chemical incorporation into the matrix [6]. As one Handbook of Stimuli-Responsive Materials. Edited by Marek W. Urban

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Photoresponsive Nanogels Formed by the Self-Assembly of Spiropyrane-Bearing Pullulan That Act as Artificial Molecular Chaperones

Cited by 113 publications

References 35 publications

Cellular uptake mechanism and intracellular fate of hydrophobically modified pullulan nanoparticles

Cellular uptake mechanism and intracellular fate of hydrophobically modified pullulan nanoparticles

Light-Sensitive Polymeric Nanoparticles Based on Photo-Cleavable Chromophores

Photochromic Responses in Polymer Matrices

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