Additive-Free Method for Enhancing the Volume Phase Transition Rate in Light-Responsive Hydrogels: A Study of Micro-Nano Bubble Water on PNIPAM-co-AAc Hydrogels.

Light-responsive hydrogels containing light-thermal convertible pigments have received interest for their possible applications in light-responsive shutters, valves, drug delivery systems, etc. However, their utility is limited by the slow response time. In this study, we investigated the use of micro-nano bubble water as a preparation solvent to accelerate the volume phase transition kinetics of poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-co-AAc) hydrogels. The hydrogels were characterized by dynamic light scattering (DLS) and dissolved oxygen (DO) measurements. The mechanical properties, surface morphology, and chemical composition of the hydrogels were analyzed by Young's modulus measurements, scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy, respectively. The results showed that hydrogels prepared with bubble water changed the volume transition rate by more than two orders of magnitude by simply changing the standing time of the bubble water for only a few hours. The cooperative diffusion coefficients obtained from the light-induced volume transition kinetics correlated linearly with Young's modulus and metastable state swelling ratio. Our results suggest that bubbles act as efficient water channels, thereby modulating the response rate and providing a simple, additive-free method for preparing hydrogels with a wide range of response rates.

Macroscopic Pattern Formation of Alginate Gels in a Two-Dimensional System.

Macroscopic spatial patterns were formed in calcium alginate gels when a drop of a calcium nitrate solution was placed on the center of a sodium alginate solution on a petri dish. These patterns have been classified into two groups. One is multi-concentric rings consisting of alternating cloudy and transparent areas observed around the center of petri dishes. The other is streaks extending to the edge of the petri dish, which are formed to surround the concentric bands between the concentric bands and the petri dish edge. We have attempted to understand the origins of the pattern formations using the properties of phase separation and gelation. The distance between two adjacent concentric rings was roughly proportional to the distance from where the calcium nitrate solution was dropped. The proportional factor p increased exponentially for the inverse of the absolute temperature of the preparation. The p also depended on the concentration of alginate. The pattern characteristics in the concentric pattern agreed with those in the Liesegang pattern. The paths of radial streaks were disturbed at high temperatures. The length of these streaks shortened with increasing alginate concentration. The characteristics of the streaks were similar to those of crack patterns resulting from inhomogeneous shrinkage during drying.

Effect of UV Irradiation of Pre-Gel Solutions on the Formation of Collagen Gel Tubes.

Hollow collagen gels are promising materials for drug/cell delivery systems to promote tissue regeneration because they may be able to function as carriers for these types of loads. Controlling the cavity size and swelling suppression is essential to expand the applications and improve the usability of such gel-like systems. We investigated the effects of UV-treated collagen solutions as a pre-gel aqueous mixture on the formation and properties of the hollow collagen gels in terms of their preparation range limits, morphology, and swelling ratio. The UV treatment thickened the pre-gel solutions, which allowed hollowing at lower collagen concentrations. This treatment also prevents the over-swelling of the hollow collagen rods in PBS buffer solutions. The UV-treated collagen solutions provided a large lumen space in the prepared collagen hollow fiber rods with a limited swelling ratio, allowing vascular endothelial cells and ectodermal cells to be cultured separately in the outer and inner lumen.

Neuron-specific enolase levels immediately following cardiovascular surgery is modulated by hemolysis due to cardiopulmonary bypass, making it unsuitable as a brain damage biomarker.

Neuron-specific enolase (NSE) is one of the biomarkers used as an indicator of brain disorder, but since it is also found in blood cell components, there is a concern that a spurious increase in NSE may occur after cardiovascular surgery, where cardiopulmonary bypass (CPB) causes hemolysis. In the present study, we investigated the relationship between the degree of hemolysis and NSE after cardiovascular surgery and the usefulness of immediate postoperative NSE values in the diagnosis of brain disorder. A retrospective study of 198 patients who underwent surgery with CPB in the period from May 2019 to May 2021 was conducted. Postoperative NSE levels and Free hemoglobin (F-Hb) levels were compared in both groups. In addition, to verify the relationship between hemolysis and NSE, we examined the correlation between F-Hb levels and NSE levels. We also examined whether different surgical procedures could produce an association between hemolysis and NSE. Among 198 patients, 20 had postoperative stroke (Group S) and 178 had no postoperative stroke (Group U). There was no significant difference in postoperative NSE levels and F-Hb levels between Group S and Group U (p = 0.264, p = 0.064 respectively). F-Hb and NSE were weakly correlated (r = 0.29. p < 0.01). In conclusion, NSE level immediately after cardiac surgery with CPB is modified by hemolysis rather than brain injury, therefore it would be unreliable as a biomarker of brain disorder.

Microenvironmental elements singularity synergistically regulate the behavior and chemosensitivity of endometrioid carcinoma.

The importance of the microenvironment is widely recognized as it regulates not only malignant cell behavior but also drug sensitivity. The cancer cell microenvironment is composed of biological, physical and chemical elements, and simultaneous reproduction of these three elements are important conditions investigated in cancer research. In the present study, we focused on the epidemiological and anatomical specificities of endometrioid carcinoma, obesity (biological), fluid flow (physical) and anticancer agents (chemical) to target the specific microenvironmental elements of endometrioid carcinoma. To elucidate the individual effects of these elements on endometrioid carcinoma and to investigate the relationships between these factors, we developed an adipose tissue fragments (ATFs)-embedded cell disc under a rotational culture method to generate carcinoma-stroma interactions and to create fluid flow. ATFs and fluid flow individually or synergistically influenced proliferative cellular behavior and the morphological changes underlying endometrioid carcinoma. ATFs and fluid flow also governed the expression of extracellular signal-regulated kinase and p38 signaling synergistically or individually, depending on the endometrioid carcinoma cell type. Adipose tissue induced chemoresistance to cis-diamminedichloro-platinum (CDDP) in endometrioid cancer, but the resistance effect was abolished by fluid flow. Thus, a simple reconstructed model was established to investigate three elements of the microenvironment of endometrioid carcinoma in vitro. This culture model unequivocally demonstrated the individual and synergistic effects of the three elements on endometrioid carcinoma. This new culture model is a promising tool for elucidating the mechanisms underlying endometrioid carcinoma and for developing further treatment strategies.

Light-driven autonomous swing of multi-layered hydrogel.

Light-driven self-oscillators without electronic circuits or conventional heat engines are carbon-emission-free systems and hold promise for developing autonomous transmission pumps and self-swimming micromotors. Thermosensitive hydrogels as self-oscillators can be used in the exploitation of low-temperature heat sources and in medical applications since the driving temperature is close to body temperature. Here, the autonomous swinging of the hydrogel was achieved by irradiating a constant light beam onto a head laminated with two thermosensitive hydrogels with different transition temperatures. Hysteresis resulting from the transition point difference between the two hydrogels allowed the light-driven self-oscillation without self-shadowing from the irradiation. The proposed theoretical model and numerical simulations explain this light-driven continuous swing, and the results agree qualitatively well with the experiments.

Mixing Behavior of the Binary Monolayers of Fatty Acids Based on Their Cohesive Energy Differences.

The morphology involving the height difference and the surface roughness of the binary monolayers of saturated fatty acids were evaluated using atomic force microscopy (AFM) to investigate the mixing behavior of their monolayers. AFM observations revealed that the mixed monolayers of (palmitic acid/arachidic acid) and (arachidic acid/lignoceric acid), which had four methylene group differences between fatty acids, were in a molecularly mixed state. Further, the mixed monolayer of (stearic acid/lignoceric acid), which had six methylene group differences, was in a phase-separated state. From the results of the present and previous studies, it became clear that the difference in the cohesive energy between fatty acids, which corresponds to the enthalpy difference, was an important factor in determining whether the molecular aggregation state of a fatty acid mixed monolayer was in a molecularly mixed or phase-separated state. Moreover, the boundary value of cohesive energy difference was approximately 2.5 kJ mol-1 at a subphase temperature of 293 K.

One-Pot Preparation of Collagen Tubes Using Diffusing Gelation.

One-pot gelation in capillary glass tubes with carbonate-based buffer solution allows the formation of hollow collagen gels (collagen tubes) with an outer diameter of 1 mm or less. The preparation conditions of collagen concentration, buffer concentration, and capillary diameter impacted the ratio and size of the hollow gel and allowed for morphological control of the cavity. The morphology of the hollows suggests that their vacancies are the result of macroscopic phase separation and pinning due to gelation. Mechanical strength measurements of the dried collagen gel tubes demonstrated that the collagen concentration determines their Young's modulus and maximum stress and that the material is strong enough for practical use. In vitro seeding studies of vascular endothelial cells demonstrated the possible formation of endothelial cells in layers in the gel lumen.

Macroscopic Banding Pattern of Collagen Gel Formed by a Diffusion-Reaction Process.

Shapes and patterns observed in internal organs and tissues are reproducibly and robustly produced over a long distance (up to millimeters in length). The most fundamental remaining question is how these long geometries of shape and pattern form arise from the genetic message. Recent studies have demonstrated that extracellular matrix (ECM) critically participates as a structural foundation on which cells can organize and communicate. ECMs may be a key to understanding the underlying mechanisms of long-distance patterning and morphogenesis. However, previous studies in this field mainly focused on the complexes and interaction of cells and ECM. This paper pays particular attention to ECM and demonstrates that collagen, a major ECM component, natively possesses the reproducible and definite patterning ability reaching centimeter-scale length. The macroscopic pattern consists of striped transparent layers. The observation under crossed Nicols demonstrates that the layers consist of alternately arranged polarized and unpolarized parts. Confocal fluorescence microscopy studies revealed that the polarized and unpolarized segments include collagen-rich and -poor regions, respectively. The patterning process was proposed based on the Liesegang banding formation, which are mineral precipitation bands formed in hydrogel matrixes. These findings will give hints to the questions about long-distance cell alignment and provide new clues to artificially control cell placement over micron size in the field of regenerative medicine.

Bystander effects induced by the interaction between urothelial cancer cells and irradiated adipose tissue-derived stromal cells in urothelial carcinoma.

Cell-cell interactions between cancer cells and neighboring adipose tissue-derived stromal cells (ATSCs) are known to regulate the aggressiveness of cancer cells. In addition, the radiation-induced bystander effect is an important modulator of cancer cell kinetics. Radiation therapy is often given for urinary cancer, but the biological effects of the irradiated cancer stroma, including adipose tissue, on urothelial carcinoma (UC) remain unclear. We investigated the bystander effect of irradiated ATSCs on UC using a collagen gel culture method to replicate irradiated ATSC-cancer cell interactions after a single 12-Gy dose of irradiation. Proliferative activity, invasive capacity, protein expression and nuclear translocation of p53 binding protein-1 (53BP1) were analyzed. Irradiated ATSCs significantly inhibited the growth and promoted the apoptosis of UC cells in comparison to non-irradiated controls. The invasiveness of UC cells was increased by irradiated ATSCs, but not irradiated fibroblasts. Nuclear translocation of 53BP1 protein due to the bystander effect was confirmed in the irradiated group. Irradiated ATSCs regulated the expressions of the insulin receptor, insulin-like growth factor-1 and extracellular signal-regulated kinase-1/2 in UC. In conclusion, the bystander effect of irradiated ATSCs is a critical regulator of UC, and the actions differed depending on the type of mesenchymal cell involved. Our alternative culture model is a promising tool for further investigations into radiation therapy for many types of cancer.

Non-Equilibrium Phase-Separated State of(Palmitic Acid/Lignoceric Acid) Mixed Monolayer.

The effect of solvent species and quantity of solvent used for spreading on the morphology of Langmuir monolayer composed of palmitic and lignoceric acids was investigated based on atomic force microscopy observations. The variation in domain size depending on the evaporation time of the spreading solution indicated that the mixed monolayer was in a non-equilibrium phase-separated state.

Structural-Size Control of Domain from Nano to Micro: Logical Balancing between Attractive and Repulsive Interactions in Two Dimensions.

Molecules aggregate to form a structure through various interactions involving dispersion force, electrostatic force, and so on. In two-dimensional systems, a surface energetic effect is further important for the molecular aggregation structure. We show that the domain size and its morphology in the mixed monomolecular film composed of hydrocarbon and fluorocarbon skeletons with different surface free energies extremely change depending on pH and NaCl concentration in the subphase. Such morphological changes can be interpreted by the balance of dipole density and line tension, which help in the development of an understanding of phase separation phenomena and provide a novel technique for structural control in two dimensions.

Promotion of cell adhesion by low-molecular-weight hydrogel by Lys based amphiphile.

Hydrogels formed by low-molecular hydrogelators have been used as anti-microbial agents and cell-attachment materials. However the biomedical application of low-molecular gelators is slowly progressing compared to the hydrogels formed by polymer hydrogelator that is applied to biomedical application such as tissue engineering and biomedical regions. To obtain a simple molecular model for potent and prospective usage of low-molecular hydrogelators, we designed a Lys-based hydrogelator which was mimic to the poly cationic poly-l-lysine that promotes cells to attach to a plastic plate nonspecifically. The gel-coating led to cause 10-fold cell attachment compared to no-coating well. Also five-time cells were attached to the well compared to the poly-l-lysine coating. From the competitive assay, these hydrogels could interact with cells through electrostatic interaction between positive charge from -NH3(+) in the hydrogelator and negative charge from substances on the cell surface such as glycosaminoglycans. This strong adhesive ability can be useful for the tissue engineering and molecular glue regions using low-molecular hydrogels in the future.

Self-pulsation observed in pH-sensitive microcapsules.

In this study, self-pulsating microparticles have been successfully prepared using a pH-sensitive and permselective membrane system.

Formation of layered perovskite structure by folding monolayer during compression.

The morphology and layered structure of an alkyl ammonium bromide ultrathin film prepared on an aqueous solution of lead bromide were investigated on the basis of surface pressure-area curve measurements, reflection spectrum measurements, X-ray reflectivity measurements and atomic force microscopic observations. It became apparent that the layered structure sandwiched a two-dimensional inorganic layer between two organic monolayers was formed by folding the monolayer by compression on an aqueous PbBr2 solution.

Nanomosaic: formation of nanodomains confined in a two-dimensional molecular plane.

Atomic force microscopy observations of a (hydrocarbon guanidinium/fluorocarbon carboxylic acid) mixed monolayer revealed that a nanoscopic phase-separated structure was formed by a combination of attractive interaction between the oppositely charged head groups and repulsive phase separation of the hydrocarbon and fluorocarbon chains.

Liesegang pattern formation in kappa-carrageenan gel.

We report a new class of the spatial pattern formation process in which the gel plays essential roles. The system studied here is the solution of kappa-carrageenan in which potassium chloride is diffused. The solution transforms into the gel state with the diffusion of potassium chloride. Then the stripe pattern, which is perpendicular to the direction of the diffusion of potassium chloride, appears within the gel. The pattern thus formed in the gel is studied as a function of the concentration of the solution of potassium chloride. We find that the dense region of the stripe pattern consists of the liquid crystalline gel, whereas the dilute region is the amorphous gel. The transition from the amorphous gel to the liquid crystalline gel, hence, occurs in the gel state of kappa-carrageenan. The gel behaves as a pattern-forming substance as well as the supporting medium of the pattern in this system. The period and the thickness of the layers of liquid crystalline gel are analyzed. Both the period and the thickness of the layers are found to depend strongly on the concentration of the solution of potassium chloride.

Preparation and characterization of core-shell nanoparticles hardened by gamma-ray.

Core-shell nanoparticles have been prepared by irradiation of gamma-ray on block copolymer micelles consisting of hydrophilic polyacrylic acid and hydrophobic polyisoprene with each 40 monomer units. The structure was determined by means of dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and atomic force microscopy (AFM). The size distribution of the core-shell nanoparticles determined by DLS and AFM was very narrow. The average diameter of the particles decreased from 48 nm for the original micelles to 26 nm by the irradiation of 30 kGy. The core size determined by SAXS combined with DLS was roughly constant of 10 nm, irrespective of irradiation dose, whereas the shell thickness of the micelles was twice as large as the core size, and decreased with increasing irradiation dose.

Re-entrant volume phase transition of hydrogel membrane of microcapsule.

Re-entrant volume phase transition of hydrogel wall membrane of microcapsules (MC) was first observed using MC suspensions consisting of poly (L-lysine-alt-terephthalic acid) wall and aqueous inner and outer solutions with different pHs. To analyze the dynamics of the re-entrant phase transition, we extended the theory for the swelling and the shrinking dynamics of the microcapsule gel [T. Narita, T. Yamamoto, D. Suzuki, T. Dobashi, Langmuir 19 (2004) 4051]. In the theory, the microcapsule size and the force constant for the driving force which gives rise to the size relaxation were chosen as the thermodynamic variables. The time course of the cross-sectional area of the microcapsules fitted well to the theoretical equations, and the time constants determined as the fitting parameters were discussed in terms of the force constant relaxation and the size relaxation.

Single-particle light scattering study of polyethyleneglycol-grafted poly(ureaurethane) microcapsule in ethanol.

Microcapsules having polyethyleneglycol-grafted poly(ureaurethane) (PUU) membrane and di-2ethylhexyl phthalate core have been prepared, and the structure when they were suspended in dispersing ethanol have been studied by means of single-particle light scattering method. The PUU membrane was synthesized from monomers with aromatic functional groups (microcapsule MC110) and hexamethylene functional groups (microcapsule MC160). Because the outer and inner solvent passed through the membrane easily, the outside and inside of the membrane were the same at the equilibrium state. The thickness of the wall membrane was significantly smaller than that calculated from the overall weight ratio of the wall-forming material and the core solvents. It was attributed to low affinity of PUU membranes and ethanol.