Flow-driven synthesis of calcium phosphate-calcium alginate hybrid chemical gardens

Dynamic Flow-Assisted Nanoarchitectonics

The solution to societal problems such as energy, environmental, and biomedical issues lies in the development of functional material systems with the capacity to address these problems. In the course of human development, we are entering a new era in which nanostructure control is considered in the major development of functional materials. The new concept of nanoarchitectonics is particularly significant in this regard, as it comprehensively promotes further development of nanotechnology and its fusion with materials chemistry. The integration of nanoscale phenomena and macroscopic actions is imperative for practical production of functional materials with nanoscale structural precision. This review focuses on dynamic flow-assisted nanoarchitectonics, wherein we explore the organization and control of functional structures by external mechanical stimuli, predominantly fluid flow. The review then proceeds to select some examples and divide them into categories for the purpose of discussion: structural organization by (i) natural flow, (ii) flow or stress created with artificial equipment or devices (forced flow), and (iii) flow at a specific field, namely interfaces, that is, layer-by-layer (LbL) assembly and the LB method. The final perspective section discusses the future research directions and requirements for dynamic flow-assisted nanoarchitectonics. The meaningful and effective use of nanotechnology and nanoarchitectonics in materials science is set to be a major area of focus in the future, and dynamic flow-assisted nanoarchitectonics is poised to play a significant role in achieving this objective.

Sodium Butyrate-Loaded Microspheres With Enhanced Bioavailability for Targeted Treatment of Intestinal Barrier Injury

Intestinal barrier dysfunction is related to diseases such as inflammatory bowel disease (IBD) and severe acute pancreatitis (SAP). Butyrate and its derivatives (e.g., sodium butyrate (SB)) can alleviate gut inflammatory responses. Nevertheless, these substances usually cannot fully exert protective effects due to low bioavailability. This research aimed to offer microspheres for treating intestinal barrier injury. Sodium alginate solution is prepared to dissolve SB, followed by mixing with chitosan (CS)-protocatechuic aldehyde (PA)/calcium chloride solution. The required CS-PA/calcium alginate/SB (CPC/SB) microspheres are formed in this manner. Subsequently, the therapeutic effects of CPC/SB microspheres on intestinal barrier injury through in vivo dextran sulfate sodium salt (DSS)-induced IBD and sodium taurocholate (STC)-induced SAP models is explored. Results: The CPC/SB microspheres exhibited excellent antioxidant properties. In vivo bioluminescence imaging experiment confirmed the microspheres effectively targeted the inflammatory gut in IBD. Further in vivo experimental results indicated the microspheres significantly repaired intestinal barrier damage, exerting protective effects in IBD and SAP. Additionally, 16S rDNA sequencing explained the microspheres can regulate the balance between harmful and beneficial bacteria (such as Alistipes, Odoribacter, and Rikenellaceae RC9). This study provides a possible synthetic strategy of microsphere carriers to serve as a potential therapeutic tool for intestinal barrier injury.

Self-propulsion of a calcium alginate surfer

A droplet of sodium alginate dripped into calcium chloride solution results in plate or boat shaped hydrogels. Both exhibit several minute-long self-propelled motion on the liquid surface without any extra fuel added, offering a new method to making active materials. By changing the initial concentrations, we are able to tune the transient dynamic activities from translational to rotational or stop-and-run motion. Dynamics are governed by osmotic pressure induced Marangoni effect, depending on the density difference and initial concentrations.

Pattern selection by material aging: Modeling chemical gardens in two and three dimensions

Chemical gardens are complex, often macroscopic, structures formed by precipitation reactions. Their thin walls compartmentalize the system and adjust in size and shape if the volume of the interior reactant solution is increased by osmosis or active injection. Spatial confinement to a thin layer is known to result in various patterns including self-extending filaments and flower-like patterns organized around a continuous, expanding front. Here, we describe a cellular automaton model for this type of self-organization, in which each lattice site is occupied by one of the two reactants or the precipitate. Reactant injection causes the random replacement of precipitate and generates an expanding near-circular precipitate front. If this process includes an age bias favoring the replacement of fresh precipitate, thin-walled filaments arise and grow-like in the experiments-at the leading tip. In addition, the inclusion of a buoyancy effect allows the model to capture various branched and unbranched chemical garden shapes in two and three dimensions. Our results provide a model of chemical garden structures and highlight the importance of temporal changes in the self-healing membrane material.

From Balloon to Crystalline Structure in the Calcium Phosphate Flow-Driven Chemical Garden

We have studied the calcium phosphate precipitation reaction by producing chemical gardens in a controlled manner using a three-dimensional flow-driven technique. The injection of the phosphate containing solution into the calcium ion reservoir has resulted in structures varying from membranes to crystals. Dynamical phase diagrams are constructed by varying chemical composition and flow rates from which three different growth mechanisms have been revealed. The microstructural analysis by scanning electron microscopy and powder X-ray diffraction confirmed the morphological transition from membrane tubes to crystalline branches upon decreasing pH.

Growth of chemical gardens in gaseous acidic atmospheres

The generation of chemobrionic architectures through slow injection of aqueous silicate solution in gaseous TiCl₄ is demonstrated. The tubes were characterized by XRD, SEM and wet chemistry control experiments, and their mechanism of formation was unraveled. These structures serve as laboratory models for calthemites or soda straws.

Dissimilar chemobrionic growth in copper silicate chemical gardens in the absence or presence of light

The effect of the absence of light on chemical garden growth has been neglected although the gardens resemble hydrothermal vents that grow in dark in the sea/ocean. Herein, we report the differential growth of chemobrionic structures in copper silicate when identical reactions to yield copper silicate chemical gardens were carried out in the presence or absence of light. Irradiating the copper silicate chemical garden during its growth with different wavelengths of light independently resulted in morphologically divergent tubes.