Abstract:Two coupled polymer gels, showing volume oscillation caused by the Belousov-Zhabotinsky (BZ) reaction, were investigated to understand the system composed of mechanically coupled chemical oscillators. The two gels were connected with a movable plastic sheet in between and placed under constant compression. Synchronization between two identical gels occurred in a range of compression ratios. The phase difference between the two oscillating gels was not zero; instead, they showed alternate swelling-deswelling os… Show more
“…Consequently, Δ C decreases with time, which is consistent with the observed decreasing slope shown in Figure j. Once the size of the colloidosomes reached a specific value (∼121 μm) after a certain period (∼45 min), the colloidosomes started to exhibit periodic oscillation (as shown in Figure e–h and the right rectangle in Figure i) due to the reaction-triggered chemomechanical oscillation; this oscillation commonly occurred in previous reports of catalyst-loaded hydrogel-based systems. − The mechanical oscillations were due to the chemical reactions generating the oscillation of the catalyst state between Ru 2+ /Ru 3+ , which consequently generated a corresponding hydrophilic/hydrophobic oscillation in the building blocks (Ruthenium-functionalized microgels) for the colloidosomes . The skeleton of the colloidosomes therefore displayed microscopic size oscillations because these building blocks were intercrosslinked by the polymer linkers.…”
Uniformly sized and cross-linked colloidosomes were prepared via microfluidic emulsification combined with a post-cross-linking reaction between NH 2 /ruthenium dual-functionalized microgels and poly(N-isopropylacrylamide)-r-(N-acryloxysuccinimide)-based polymers. When mixed with catalyst-free Belousov− Zhabotinsky reaction substrates, the colloidosomes first experienced decrease in size and then exhibited mechanical oscillations. In addition, the colloidosome behavior can be regulated using different types of light, which then displayed reversible deswelling/swelling cycles under alternating white light on/off stimuli, but only expanded and even ruptured under the stimulus of continuous blue light illumination. These multisensitive colloidosomes could be potentially applied in the fields of photo memory devices and blue light-triggered release vehicles.
“…Consequently, Δ C decreases with time, which is consistent with the observed decreasing slope shown in Figure j. Once the size of the colloidosomes reached a specific value (∼121 μm) after a certain period (∼45 min), the colloidosomes started to exhibit periodic oscillation (as shown in Figure e–h and the right rectangle in Figure i) due to the reaction-triggered chemomechanical oscillation; this oscillation commonly occurred in previous reports of catalyst-loaded hydrogel-based systems. − The mechanical oscillations were due to the chemical reactions generating the oscillation of the catalyst state between Ru 2+ /Ru 3+ , which consequently generated a corresponding hydrophilic/hydrophobic oscillation in the building blocks (Ruthenium-functionalized microgels) for the colloidosomes . The skeleton of the colloidosomes therefore displayed microscopic size oscillations because these building blocks were intercrosslinked by the polymer linkers.…”
Uniformly sized and cross-linked colloidosomes were prepared via microfluidic emulsification combined with a post-cross-linking reaction between NH 2 /ruthenium dual-functionalized microgels and poly(N-isopropylacrylamide)-r-(N-acryloxysuccinimide)-based polymers. When mixed with catalyst-free Belousov− Zhabotinsky reaction substrates, the colloidosomes first experienced decrease in size and then exhibited mechanical oscillations. In addition, the colloidosome behavior can be regulated using different types of light, which then displayed reversible deswelling/swelling cycles under alternating white light on/off stimuli, but only expanded and even ruptured under the stimulus of continuous blue light illumination. These multisensitive colloidosomes could be potentially applied in the fields of photo memory devices and blue light-triggered release vehicles.
“…It is also noteworthy that oscillations have been detected in the BZ reaction in viscous bulk solutions. In this case, oscillations in volume 32 and viscosity 35 were observed. The latter were shown to correlate with reversible aggregation of polymers, accompanied by oscillations in redox potential.…”
Section: Discussionmentioning
confidence: 81%
“…Instead, these observations suggest that glycolysis, at least in part, is controlled by a cell-wide property (i.e., the physical state of water), which through the A-I mechanism can transfer a response to the relevant glycolytic enzymes. The fact that, e.g., enzymatic activity 52 , 53 or redox potential 32 – 35 can be affected by the physical state of water makes it plausible that the dynamic behaviour of glycolysis is also affected. Figure 7 Latrunculin B obliterates oscillations in NADH and ACDAN.…”
Section: Discussionmentioning
confidence: 99%
“…Although the idea has not yet been thoroughly explored in biological contexts, it is not unusual for non-biological oscillating chemical reactions to respond to macromolecular crowding. For example, it is well known that the Belousov-Zhabotinskii (BZ) reaction, when carried out in viscous aqueous solutions containing various polymers, may show oscillations in solution viscosity and volume that are synchronized with oscillations in redox potential 32 – 35 . Furthermore, it has been demonstrated that synchronization involves reversible aggregations of polymers that themselves depend on the redox state of the metal complex catalysing the BZ reaction 35 and that the oscillatory behaviour depends on the viscosity of the solution.…”
We explored the dynamic coupling of intracellular water with metabolism in yeast cells. Using the polarity-sensitive probe 6-acetyl-2-dimethylaminonaphthalene (ACDAN), we show that glycolytic oscillations in the yeast S. cerevisiae BY4743 wild-type strain are coupled to the generalized polarization (GP) function of ACDAN, which measures the physical state of intracellular water. We analysed the oscillatory dynamics in wild type and 24 mutant strains with mutations in many different enzymes and proteins. Using fluorescence spectroscopy, we measured the amplitude and frequency of the metabolic oscillations and ACDAN GP in the resting state of all 25 strains. The results showed that there is a lower and an upper threshold of ACDAN GP, beyond which oscillations do not occur. This critical GP range is also phenomenologically linked to the occurrence of oscillations when cells are grown at different temperatures. Furthermore, the link between glycolytic oscillations and the ACDAN GP value also holds when ATP synthesis or the integrity of the cell cytoskeleton is perturbed. Our results represent the first demonstration that the dynamic behaviour of a metabolic process can be regulated by a cell-wide physical property: the dynamic state of intracellular water, which represents an emergent property.
“…The classical Belousov–Zhabotinsky (BZ) oscillating reaction refers to the oscillatory cerium-catalyzed bromate oxidation of citric acid. − Since the original discovery of the BZ reaction many similar oscillating chemical reactions have been discovered that use dicarboxylic acids (malonic acid and malic acid) as the organic substrate and are catalyzed by other metals such as Fe, Ru, − Mn, − and Cu . Oscillating reactions using organic molecules instead of a catalyst have also been reported. − More recent research on the BZ reaction has focused on oscillating polymer formation, − oscillating reactions inside of micelles, , communication between such micelles as a model system of neural networks, − and the complex mathematics of oscillating systems. , …”
The acidity dependence of the iron-catalyzed bromate-malonic acid Belousov-Zhabotinsky reaction was studied in the range 0.36 M < [HSO] < 1.20 M, and the temporal evolutions of the oscillation patterns were analyzed. The experimental results show that the period times PT decrease exponentially with increasing acidity and that the period times parallel the decrease of the reduction times RT with increasing acidity. Simulations using the reactions of the commonly accepted core reaction mechanism failed to match the measurements even in a qualitative fashion. However, we found that compelling agreement between the experiments and the simulations can be achieved over the entire range with the inclusion of second-order proton-catalysis of the oxidation of bromomalonic acid (BrMA) by the [Fe(phen)] species in the reaction identified in this paper as reaction 9 (R9), and this [H] dependence is informative about the species involved in the outer sphere electron transfer reaction. The trication [Fe(phen)] species is stabilized by ion pairing and solvation, and one may anticipate the presence of [Fe(phen)(HSO) (HO) ] species ( n = 0-3). Our results suggest that the removal of aggregating HSO ions by protonation creates a better oxidant and facilitates the approach of the reductant BrMA, and the second-order [H] dependence further suggests that BrMA is primarily oxidized by a doubly charged [Fe(phen)(HSO)(L) ] species. Considering the complexity of the BZ system and the uncertainties in the many reaction rate constants, we were somewhat surprised to find this high level of agreement by (just) the replacement of R9 by R9'. In fact, the near-quantitative agreement presents a powerful corroboration of the core reaction mechanism of the BrMA-rich BZ reaction, and the replacement of R9 by R9' extends the validity of this core reaction mechanism to acidities above and below the typical acidity of BZ reactions ([H] ≈ 1 M).
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