A Further Study on Calcium Phosphate Gardens Grown from the Interface of κ‐Carrageenan‐based Hydrogels and Counterion Solutions

Abstract

Originating from the concept of classical chemical gardens, a new field coined 'chemobrionics' has recently emerged. In the present work, two chemobrionic systems grown from a hydrogel/liquid interface at different time scales (for 1, 7, 14 or 28 days) were investigated, i. e., a calcium-based hydrogel with a phosphate counterion solution (Ca-gel) and a phosphatebased hydrogel with a calcium counterion solution (P-gel). The initial pH changes of the systems were investigated, and the obtained tubular structures were studied using optical microscopy, SEM, AFM, PXRD and TGA. One of the important findings is that the tubes obtained in the Ca-gel system were straight and long, which could be explained by the larger pH difference observed between the hydrogel and the counterion solution in this system (ΔpH ~2.1) compared to the P-gel system (ΔpH ~0). The Ca-gel structures remained overall more amorphous even though increased crystallinity was observed in both systems with increased time spent in counterion solution. Both systems contained hydroxyapatite phases, with additional calcite phases observed for the P-gel structures and traces of k-carrageenan for the Ca-gel structures. Our study provides a promising method for controlling tubular macrostructures through adjusting the reaction conditions such as maturation time and pH.

Comparative Evaluation of Chemical Garden Growth Techniques

“…C−O band was attributed to the presence of CO 3 2− , which was formed due to the carbon dioxide from the air dissolving into solutions. 33,34 The shift from ∼1070 to ∼1110 cm −1 might be a result of conformational variations or the hydroxylation/dehydroxylation process. 35−37 According to the obtained results, the seed method led to the formation of the most irregular and unstable structures, while membrane growth produced the most standard precipitates in a particular shape due to the dialysis membrane acting as a template.…”

“…These peaks were assigned to Si–O–Si vibrations or C–O stretching motions. C–O band was attributed to the presence of CO 3 2– , which was formed due to the carbon dioxide from the air dissolving into solutions. , The shift from ∼1070 to ∼1110 cm –1 might be a result of conformational variations or the hydroxylation/dehydroxylation process. − …”

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

“…It is still in focus, because controlling the crystallization process is especially challenging. , However, we can create structures with appropriate planning in a controlled manner . For example, pH can significantly influence not only the tubular growth but also the final morphology. , Therefore, it is important to select the starting parameters well ahead.…”

Bio‐Inspired Far‐From‐Equilibrium Hydrogels: Design Principles and Applications

“…Recently, hydrogels have attracted increasing attention and have become one of the most popular soft materials. [1][2][3][4][5] Hydrogels are swellable networks that consist of a significant water content, displaying physical properties similar to those of soft biological tissues. Remarkably, hydrogels exhibit the capability to retain substantial amounts (> 95 %) of water through surface tension or capillary effects.…”

“…Recently, hydrogels have attracted increasing attention and have become one of the most popular soft materials [1–5] . Hydrogels are swellable networks that consist of a significant water content, displaying physical properties similar to those of soft biological tissues.…”