Synthesis and structure of photodegradable 1-(4,5-dimeth-oxy-2,3-di-nitro-phen-yl)-2-methyl-propyl N-butyl-carbamate.

The reaction of 1-(4,5-dimeth-oxy-2,3-di-nitro-phen-yl)-2-methyl-propan-1-ol and butyl-iso-cyanate using di-butyl-tin dilaurate as a catalyst afforded 1-(4,5-dimeth-oxy-2,3-di-nitro-phen-yl)-2-methyl-propyl N-butyl-carbamate, C17H25N3O8, which released butyl-amine upon photoirradiation. Single crystals of the title compound were grown in a 1:1 mixed solution of hexane and ethyl acetate. Two nitro groups and one meth-oxy group are twisted out of the plane of the aromatic ring in the novel photo-protecting group. Inter-molecular hydrogen bonds are observed between N-butyl-carbamate moieties parallel to the a axis.

Spreading Dynamics of a Precursor Film of Ionic Liquid or Water on a Micropatterned Polyelectrolyte Brush Surface.

Time evolution of the microscopic wetting velocity of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI) or water on a micrometer-scale line-patterned surface with a poly(3-sulfopropyl methacrylate) brush and a hydrophobic perfluoroalkyl monolayer was precisely measured by direct observation using optical microscopy and a selective dyeing method over a long period (178 days). When a liquid droplet was placed on the dyed line-patterned brush surface, the liquid penetrated and spread into the polymer brush layer, forming a precursor thin film that extended beyond the macroscopic contact line. The elongation proceeded in two stages by an adiabatic process followed by a diffusive process. The elongation distance X increased with time in proportion to t2.6 for water and t0.81 for EMI-TFSI during the adiabatic process. In a diffusive process, the advancing velocity of the precursor film was markedly reduced to be expressed as X ∝ t0.66 for water and X ∝ t0.21 for EMI-TFSI, indicating that the diffusive process was affected by the energy dissipation of the wetting system. The high viscosity and the strong molecular interaction of EMI-TFSI with the polymer brush gave a large entropy change during the wetting process to result in a slower spreading velocity.

Preparation of a Series of Photoresponsive Polymersomes Bearing Photocleavable a 2-nitrobenzyl Group at the Hydrophobic/Hydrophilic Interfaces and Their Payload Releasing Behaviors.

In this study, the structure-function relationships of a series of polymersomes composed of well-defined amphiphilic diblock copolymers were investigated. The building blocks were synthesized by clicking hydrophobic polymers, synthesized beforehand, and commercially available poly(ethylene glycol) with photocleavable 2-nitrobenzyl compounds bearing alkyne and maleimide functionalities. All of the tested polymersomes preserved their hollow structures even after sufficient photoirradiation. Nevertheless, the release rate of an entrapped anionic fluorophore was highly dependent on the molecular weight and the type of hydrophobic polymer, as well as on the presence or absence of the charged end groups. Moreover, the polymersomes with a 2-nitrosobenzyl photolysis residue within the hydrophobic shells exhibited photo-induced payload release after complete photolysis. It was concluded that the payload release was mediated by photo-induced permeability changes of the hydrophobic shells rather than the decomposition of their overall structures.

Epidermal growth factor-nanoparticle conjugates change the activity from anti-apoptotic to pro-apoptotic at membrane rafts.

The proliferation epidermal growth factor (EGF) is known to acquire contradictory apoptotic activities upon conjugation with gold nanoparticles (GNPs) through hitherto unknown mechanisms. Here, we identified an essential role of membrane rafts in the drastic activity switching of EGF-GNPs through the following intracellular signaling. (1) In contrast to the rapid diffusion of activated EGF receptor after the soluble EGF stimulation, the receptor is confined within membrane rafts upon binding to the EGF-GNPs. (2) This initial receptor confinements switch its endocytosis process from normal clathrin-mediated endocytosis to caveolin-mediated one, changing the phosphorylation dynamics of essential downstream kinases, i.e., extracellular signal-regulated kinase and AKT. Importantly, the destruction of membrane rafts by ß-cyclodextrin reversed this trafficking and signaling, restoring EGF-GNPs to lost anti-apoptotic property. These results reveal the importance of GNP-mediated signal condensation at membrane rafts in conferring the unique apoptotic activity on EGF-nanoparticle conjugates. STATEMENT OF SIGNIFICANCE: Epidermal growth factor (EGF) is a small secretory protein that induces cell proliferation upon binding to its receptor existed on cellular plasma membranes. One interesting feature of the protein in the nanobiology field is, its acquisition of apoptosis-inducing (cellular suicide) activity rather than proliferative one upon conjugation to gold nanoparticles through hitherto unknown mechanisms. Here, we identified the involvement of membrane rafts, plasma membrane nanodomains enriched with cholesterol, in the apoptosis processes by changing the receptor trafficking and downstream signal transduction pathways. Moreover, the destruction of lipid rafts restored the EGF-nanoparticle conjugates with lost anti-apoptotic activity. These finding highlight potential applications of EGF-nanoparticle conjugates to cancer therapy, as the EGF receptor are highly expressed in cancer cells.

Photoactivatable Hydrogel Interfaces for Resolving the Interplay of Chemical, Mechanical, and Geometrical Regulation of Collective Cell Migration.

Collective migration is the mechanobiological interplay within migrating cell clusters and against extracellular matrixes (ECMs) underneath, mediating various physiological and pathological processes. Therefore, it is crucial to develop a robust platform on which collective migration can be studied under standardized conditions to understand how cells migrate differently between normal and disease states. We herein demonstrated phtotoactivatable hydrogel interfaces as suitable candidates for such applications. The substrate was composed of a poly(acrylamide) (PAAm) hydrogel whose surface was sequentially functionalized with poly-d-lysine (PDL) and photocleavable poly(ethylene glycol) (PEG). On the surface of the gel substrates, cell clusters with any given geometries can be prepared by controlling the irradiation patterns (geometrical cue), and their collective migration can be induced by the subsequent irradiation of the surrounding regions. Moreover, the substrate mechanical properties can be controlled by changing the composition of the PAAm hydrogel (mechanical cue), and the chemical properties were controlled by changing the amount of immobilized PDL, thereby altering the adsorbed amount of ECM proteins (chemical cue). The photoactivatable gel substrates were characterized by fluorescence microscopy, ζ-potential measurements, and the protein adsorption test. Through the study of the interplay of chemical, mechanical, and geometrical cues in the regulation of collective characteristics, we found additive effects of chemical and mechanical cues on the suppression of circular expansion by up-regulating the epithelial morphology. Also, the impact of geometrical cues became more significant by decreasing the chemical cue. We believe the present platform will be a useful research tool for the comprehensive mechanobiological analysis of collective cell migration.

Intermolecular Interaction of Polymer Brushes Containing Phosphorylcholine and Inverse-Phosphorylcholine.

Choline phosphate (CP) is a phosphobetaine-type zwitterionic functional group, referred to as inverse phosphorylcholine (PC) due to the reverse orientation of a positively charged quaternary amine and anionic phosphate in contrast to PC lipids in nature. The A unique dipole paring between CP and PC groups has attracted much attention in the biointerface research field. Herein, to evaluate the molecular interaction between the CP and PC groups in water, force-distance curve measurements using scanning probe microscopy (SPM) with a PC-group-functionalized cantilever was carried out on the surface of polymer brushes bearing the CP groups. Three types of methacrylate monomers bearing CP with ethyl (Et), methoxyethyl (MOE), and isopropyl (iPr) phosphates were synthesized in 42-71% yields, and polymerized by surface-initiated atom transfer radical polymerization to form polymer brushes on silicon wafers. The surface free energy of CP-polymer brushes with Et, MOE, and iPr was estimated to be 64.0, 61.4, and 57.4 mN m-1, respectively, based on contact angle measurements. Force-distance curve measurements of polymer brushes having a CP group was conducted in water at 25 °C by SPM using a spherical probe produced by attaching a silica particle (SiP; d = 25 µm) covered with PC or CP groups to a tipless cantilever. Adhesion force larger than 14 nN was observed between the CP-polymer brushes and PC-SiP, whereas PC-polymer brushes revealed extremely low adhesion force of less than 0.6 nN with PC-SiP and propylsilane-modified SiP. The specific attractive molecular interaction between CP and PC groups was quantitatively evaluated.

Time Evolution of Precursor Thin Film of Water on Polyelectrolyte Brush.

The microscopic wetting behavior of a water film on the line-patterned surface of a polyelectrolyte brush was directly visualized using an optical microscope by dyeing procedures. Surface line patterns of 5 and 5 µm width or 10 and 5 µm width for the polyelectrolyte brush and hydrophobic monolayer, respectively, were prepared by a photolithography process, chemical vapor adsorption method, and surface-initiated polymerization. A droplet of water containing dye was placed on the line-patterned surface. In front of the contact line, a water film with a nanometer-scale thickness, referred to as a precursor film, elongated along the polymer brush line with time. The elongation velocity at the first stage increased as the brush line width increased. On the other hand, at the second stage after the macroscopic contact line stopped moving, the precursor film continued to elongate in proportion to the 0.6 power of time, independent of the brush thickness, line width, and droplet volume.

Photo-triggered recognition between host and guest compounds in a giant vesicle encapsulating photo-pierceable vesicles.

Here, we used centrifugal precipitation to construct a giant vesicle (GV) encapsulating smaller giant vesicles (GV-in-GV) which comprises a photo-resistant outer GV and a photo-pierceable inner GV; the outer GV contained a fluorescent probe (SYBR Green I) in its inner water pool, and the inner GV contained double-stranded DNA (dsDNA) in its inner water pool. The phospholipid membrane of the inner GV was made photo-pierceable by inclusion of ca. 15mol% of a caged phospholipid in its membrane. Immediately after exposure of the GV-in-GVs to UV irradiation, strong fluorescence was detected in the inner water pool of the outer GV, indicating that dsDNA had been released from the inner GV and had complexed with the fluorescent probe. These dynamics can be recognized as a macroscopic representation of the molecular level function of a caged compound.

Evaluation of nursing interventions using minimally invasive assessments methods for patients in a persistent vegetative state.

AIM: This study aimed to evaluate the effects of nursing interventions using minimally invasive or non-invasive methods conducive to frequent use in order to assess patients in a persistent vegetative state (PVS). METHODS: We provided three nursing interventions-sitting the patient in an upright position, footbath care, and oral care-to PVS patients (n = 11) and elderly bedridden subjects with consciousness (n = 6) for 3 weeks in addition to ordinary nursing treatments. The Kohnan Score, plasma cortisol and adrenaline levels, General Well-Being Schedule score, and facial expression assessments were used as evaluation methods. RESULTS: The Kohnan Score of PVS patients declined significantly, indicating that the interventions increased patients' consciousness levels, but none of the other parameters showed significant change in either group. The change in Kohnan Score showed dependent trends for facial expression at baseline, cortisol change during the intervention, and the term of PVS. CONCLUSIONS: The data suggest three indices for predicting intervention efficacy in individuals and for assessing an intervention's contribution to quality of life improvement. Among the multiple evaluation methods, Konan Scores was the most effective. Ultimately, the three nursing interventions used in this study and Konan Score led to the optimization of nursing home care and rehabilitation for PVS patients.

Facile Preparation of Photoactivatable Surfaces with Tuned Substrate Adhesiveness.

This paper describes a facile method for the preparation of photoactivatable substrates with tuned surface density of an extracellular matrix peptide to resolve the impacts of biochemical and mechanical cues on collective cell migration. The controllability of surface ligand density was validated by cell adhesion and migration tests, complemented with fluorescence observation of an alternative ligand. Depending on the surface ligand density, HeLa cells either kept or lost collective characteristics. The present materials will be useful to address mechanobiology of collective cell migration.

Dynamic control of cell adhesion on a stiffness-tunable substrate for analyzing the mechanobiology of collective cell migration.

A method was developed for photocontrolling cell adhesion on a gel substrate with defined mechanical properties. Precise patterning of geometrically controlled cell clusters and their migration induction became possible by spatiotemporally controlled photo-irradiation of the substrate. The clusters exhibited unique collective motion that depended on substrate stiffness and cluster geometry.

Packing polymorphism in the crystal structure of 4,5-dimeth-oxy-2-nitro-benzyl acetate.

The title compound, C11H13NO6, shows two polymorphs, orange and yellow forms, both of which crystallize in the space group P21/c. The mol-ecular structures in the two polymorphs are essentially similar and adopt a planar structure, the maximum deviations for the non-H atoms being 0.1836 (13) and 0.1276 (13) Å, respectively, for the orange and yellow forms. In the orange crystal, mol-ecules are linked by an inter-molecular C-H⋯O inter-action into a helical chain along the b-axis direction. The chains are stacked along the c axis through a π-π inter-action [centroid-centroid distance = 3.6087 (11) Å], forming a layer parallel to the bc plane. In the yellow crystal, mol-ecules are connected through C-H⋯O inter-actions into a sheet structure parallel to (-302). No significant π-π inter-action is observed. The unit-cell volume of the orange crystal is larger than that of the yellow one, and this accounts for the predominant growth of the yellow crystal.

Facile preparation of a photoactivatable surface on a 96-well plate: a versatile and multiplex cell migration assay platform.

Cell migration is an essential cellular activity in various physiological and pathological processes, such as wound healing and cancer metastasis. Therefore, in vitro cell migration assays are important not only for fundamental biological studies but also for evaluating potential drugs that control cell migration activity in medical applications. In this regard, robust control over cell migrating microenvironments is critical for reliable and quantitative analysis as cell migration is highly dependent upon the microenvironments. Here, we developed a facile method for making a commercial glass-bottom 96-well plate photoactivatable for cell adhesion, aiming to develop a versatile and multiplex cell migration assay platform. Cationic poly-d-lysine was adsorbed to the anionic glass surface via electrostatic interactions and, subsequently, functionalized with poly(ethylene glycol) (PEG) bearing a photocleavable reactive group. The initial PEGylated surface is non-cell-adhesive. However, upon near-ultraviolet (UV) irradiation, the photorelease of PEG switches the surface from non-biofouling to cell-adhesive. With this platform, we assayed cell migration in the following procedure: (1) create cell-attaching regions of precise geometries by controlled photoirradiation, (2) seed cells to allow them to attach selectively to the irradiated regions, (3) expose UV light to the remaining PEGylated regions to extend the cell-adhesive area, (4) analyse cell migration using microscopy. Surface modification of the glass surface was characterized by ζ-potential and contact angle measurements. The PEGylated surface showed cell-resistivity and became cell-adhesive upon releasing PEG by near-UV irradiation. The method was applied for parallelly evaluating the effect of model drugs on the migration of epithelial MDCK cells in the multiplexed platform. The dose-response relationship for cytochalasin D treatment on cell migration behavior was successfully evaluated with high reproducibility. Interestingly, the impact of blebbistatin on cell migration was dependent upon the widths of the migrating regions, resulting in both cases of migration acceleration and deceleration. These results clearly demonstrate that the cellular response to certain drugs is highly affected by their migrating geometries. Therefore, the obtained novel photoactivatable 96-well plate serves as a useful high-throughput platform for the identification of drug candidates that have an effect on cell migration behavior.

Chloroplast RNA editing going extreme: more than 3400 events of C-to-U editing in the chloroplast transcriptome of the lycophyte Selaginella uncinata.

RNA editing in chloroplasts and mitochondria of land plants differs significantly in abundance. For example, some 200-500 sites of cytidine-to-uridine RNA editing exist in flowering plant mitochondria as opposed to only 30-50 such C-to-U editing events in their chloroplasts. In contrast, we predicted significantly more chloroplast RNA editing for the protein-coding genes in the available complete plastome sequences of two species of the spike moss genus Selaginella (Lycopodiophyta). To evaluate these predictions we investigated the Selaginella uncinata chloroplast transcriptome. Our exhaustive cDNA studies identified the extraordinary number of 3415 RNA-editing events, exclusively of the C-to-U type, in the 74 mRNAs encoding intact reading frames in the S. uncinata chloroplast. We find the overwhelming majority (61%) of the 428 silent editing events leaving codon meanings unaltered directly neighboring other editing events, possibly suggesting a sterically more flexible RNA-editing deaminase activity in Selaginella. No evidence of RNA editing was found for tRNAs or rRNAs but we identified a total of 74 editing sites in cDNA sequences of four group II introns (petBi6g2, petDi8g2, ycf3i124g2, and ycf3i354g2) retained in partially matured transcripts, which strongly contribute to improved base-pairing in the intron secondary structures as a likely prerequisite for their splicing.

A photoactivatable nanopatterned substrate for analyzing collective cell migration with precisely tuned cell-extracellular matrix ligand interactions.

Collective cell migration is involved in many biological and pathological processes. Various factors have been shown to regulate the decision to migrate collectively or individually, but the impact of cell-extracellular matrix (ECM) interactions is still debated. Here, we developed a method for analyzing collective cell migration by precisely tuning the interactions between cells and ECM ligands. Gold nanoparticles are arrayed on a glass substrate with a defined nanometer spacing by block copolymer micellar nanolithography (BCML), and photocleavable poly(ethylene glycol) (Mw  =  12 kDa, PEG12K) and a cyclic RGD peptide, as an ECM ligand, are immobilized on this substrate. The remaining glass regions are passivated with PEG2K-silane to make cells interact with the surface via the nanoperiodically presented cyclic RGD ligands upon the photocleavage of PEG12K. On this nanostructured substrate, HeLa cells are first patterned in photo-illuminated regions, and cell migration is induced by a second photocleavage of the surrounding PEG12K. The HeLa cells gradually lose their cell-cell contacts and become disconnected on the nanopatterned substrate with 10-nm particles and 57-nm spacing, in contrast to their behavior on the homogenous substrate. Interestingly, the relationship between the observed migration collectivity and the cell-ECM ligand interactions is the opposite of that expected based on conventional soft matter models. It is likely that the reduced phosphorylation at tyrosine-861 of focal adhesion kinase (FAK) on the nanopatterned surface is responsible for this unique migration behavior. These results demonstrate the usefulness of the presented method in understanding the process of determining collective and non-collective migration features in defined micro- and nano-environments and resolving the crosstalk between cell-cell and cell-ECM adhesions.

Dynamic substrate based on photocleavable poly(ethylene glycol): zeta potential determines the capability of geometrical cell confinement.

Dynamic substrates whose cell adhesiveness changes in response to an external stimulus are useful not only for patterning cells in various geometries but also for inducing cell migration or arraying heterotypic cells. The requirements for such applications are high switching efficiency in cell adhesiveness and long-term persistence of the created cellular patterns. In this study, we prepared a dynamic substrate bearing photocleavable poly(ethylene glycol) (PEG) and examined the effect of the surface PEG density and the charge of cationic base materials on the above-mentioned key requirements. An amino-terminated substrate with a certain amino group density and charge was functionalized with photocleavable PEG5K, with and without subsequent backfilling of photocleavable PEG2K. The PEG chains made the surface non-cell-adhesive, but subsequent near-UV irradiation of the substrate induced photocleavage of the PEG, eventually making the surface cell-adhesive. The substrates were analyzed by atomic force microscopy, contact angle measurements, ellipsometry, and zeta potential measurements, complemented with protein adsorption observations. Although the density of amino group in the base material affected both the grafting efficiency of the backfilling PEG and the electrokinetic potential mainly in the positive range, the latter mainly determined the protein- and cell-repelling abilities of the substrates. Furthermore, varying the surface compositions had almost no effect on the switching efficiency in the early stage of the culture, but it became more significant after culturing cells for a longer time; the cells fouled the nonirradiated PEGylated regions earlier on the surfaces with higher positive zeta potentials. These results indicate that the zeta potential is an essential factor in the long-term persistence of cellular patterns on photoactivatable substrates. This study not only provides a recipe for the development of a dynamic substrate with an adequate time frame but also clarifies how the interfacial nanoarchitectures, composed of the nanometer-scale PEG brushes and charged base materials, affect the biocompatibility.

Spatiotemporally controlled navigation of neurite outgrowth in sequential steps on the dynamically photo-patternable surface.

A great number of the neurites interconnect neuronal cells in a brain to form the complicate neural circuits, whose structures are dynamically changed with changing the numbers and destinations of the neurites. Fabricating a model of neural network in vitro is one of the promising methods to precisely assay the signal transmission and processing within the circuit as well as to examine behaviors of individual cells. In this study, aiming to fabricate the dynamically alterable neural network in vitro, the chemically modified surface with the photo-reactive self-assembled monolayer was applied to navigate the neurite outgrowth activities of differentiated PC12 cell in the spatially and temporally controlled manner. Numbers of the cell soma were effectively adhered and simultaneously arrayed according to the 25 µm square patterns, which were easily fabricated with a single shot of the 365-nm ultraviolet (UV) irradiation and pre-coated with the extracellular matrix (ECM) protein. Narrow neurites were successively guided along the 5 µm line patterns drawn on the surface by stepwise irradiation of the UV light in the intended designs and at appropriate timing. Sprouting number, elongating direction, bending, branching, and formation of autapse-like structure were controllable. The rate of neurite elongation was dependent on the ECM species, that were pre-coated beneath the cell soma, suggesting the ECM stimulated the basal side of the cell soma and affected the outgrowth process of the neurite. Navigation of the neurite elongation along the microline pattern for a primary rat brain cortex neuron was also achieved.

Switchable adhesive substrates: revealing geometry dependence in collective cell behavior.

Collective cell migration plays a major role in cancer metastasis and wound healing, therefore, several in vitro assays for studying such behavior have been developed. Using photoswitchable surfaces, we studied collective cell expansion behavior from initially precisely controlled adhesive patterns. A non-adhesive poly(ethylene glycol) (PEG) layer is conjugated to a glass coverslip via 2-nitrobenzyl groups, which cleave upon exposure to UV light, changing the surface from non-cell-adhesive to cell-adhesive without mechanical interference. Initial cell attaching areas are generated in arbitrary shapes via projection exposure through a photomask. After a growth phase, epithelial cell sheets are released from their confinement by a second illumination allowing for collective cell expansion. Our experiments with epithelial cells show that cluster size and boundary curvature modulate the expansion of the cell sheet and the formation of leader cells. At a certain cluster size, characteristics of the expansion behavior change and cells in the core are hardly affected by the boundary release. With donut-like ring structures, we demonstrate a break in symmetry between the behavior of cells along the outer convex boundary and along the inner concave boundary. Additionally, we observe that collective migration characteristics are modulated by the initial incubation time of the cell sheet.

Visualization of wounding-induced root-to-shoot communication in Arabidopsis.

It is known that wounding systemically activates the expression of various defense-related genes in plants. However, most studies of wound-induced systemic response are concerned with a leaf-to-leaf response. We have recently reported that the long distance signaling was also observed in the shoots of Arabidopsis seedling with wounded roots. We identified early and late root-to-shoot responsive (RtS) genes that were upregulated in the shoots of root-wounded seedlings at 30 min and 6 h post-injury, respectively. It is likely that the primary signals were rapidly transfered from injured roots to shoots, and then these signals were converted into chemical signals. In fact, increase of JA and OPDA content activated the expression of early and late RtS genes in shoots, respectively. In addition, we visualized wound-induced root-to-shoot response by using RtS promoter-luciferase (Luc) transgenic plants. Analysis of the AtERF13 promoter::Luc transgenic plants clearly shows that the wound-induced root-to-shoot signaling was rapidly activated via the vascular systems.

Photocontrol of cell adhesion on amino-bearing surfaces by reversible conjugation of poly(ethylene glycol) via a photocleavable linker.

Dynamic control of cell adhesion on substrates is a useful technology in tissue engineering and basic biology. This paper describes a method for the control of cell adhesion on amino-bearing surfaces by reversible conjugation of an anti-fouling polymer, poly(ethylene glycol) (PEG), via a newly developed photocleavable linker, 1-(5-methoxy-2-nitro-4-prop-2-ynyloxyphenyl)ethyl N-succinimidyl carbonate (1). This molecule has alkyne and succinimidyl carbonate at each end, which are connected by photocleavable 2-nitrobenzyl ester. Under this molecular design, the molecule crosslinked azides and amines, whose linkage cleaved upon application of near-UV light. By using aminosilanised glass and silicon as model substrates, we studied their reversible surface modification with PEG-azide (M(w) = 5000) based on contact angle measurements, ellipsometry, and AFM morphological observations. Protein adsorption and cell adhesion dramatically changed by PEGylation and the following irradiation, which can be used for cellular patterning. Also, the capability of the substrate to change cell adhesiveness by photoirradiation during cell cultivation was demonstrated by inducing cell migration. We believe this method will be useful for dynamic patterning of cells on protein-based scaffolds.