Local Light‐Controlled Generation of Calcium Carbonate and Barium Carbonate Biomorphs via Photochemical Stimulation

Abstract

Photochemical activation is proposed as a general method for controlling the crystallization of sparingly soluble carbonates in space and time. The photogeneration of carbonate in an alkaline environment is achieved upon photo-decarboxylation of an organic precursor by using a conventional 365 nm UV LED. Local irradiation was conducted focusing the LED light on a 300 μm radius spot on a closed glass crystallization cell. The precursor solution was optimized to avoid the precipitation of the photoreaction organic byproducts and prevent photo-induced pH changes to achieve the formation of calcium carbonate only in the corresponding irradiated area. The crystallization was monitored in real-time by time-lapse imaging. The method is also shown to work in gels. Similarly, it was also shown to photo-activate locally the formation of barium carbonate biomorphs. In the last case, the morphology of these biomimetic structures was tuned by changing the irradiation intensity.

Morphological Evolution of Calcite Grown in Zwitterionic Hydrogels: Charge Effects Enhanced by Gel‐Incorporation

“…This morphological control strategy may also be applied to design and synthesize novel crystal composite materials which need specific morphologies. [3,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] Experimental Section Reagent: Gelatin (G2500, gel strength ~300 g bloom, Type A) was purchased from Sigma (France). Calcium chloride anhydrous (CaCl 2 , AR), acetic acid (HAc, AR), ammonium chloride (NH 4 Cl, AR), sodium acetate (NaAc, AR), ammonium acetate (NH 4 Ac, AR), sodium hydroxide (NaOH, AR), hydrochloric acid (HCl, 36.0-38.0 wt.%) and sodium chloride (NaCl, AR) were purchased from Sinopharm Chemical Reagent Co., Ltd (China).…”

“…Employing the revealed charge effects, the calcite crystal composites with different morphologies can be flexibly prepared by adjusting the charge concentrations along the gel networks. This morphological control strategy may also be applied to design and synthesize novel crystal composite materials which need specific morphologies [3,14–28] …”

“…[3,8,14] Therefore, revealing the mechanisms of morphological evolution in biomineralization can provide new strategies for designing and synthesizing novel materials (e. g., biomedical and structural materials). [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] During biomineralization, biomacromolecule matrices (proteins, polysaccharides, etc.) are often produced by organisms first, followed by an induced crystallization of biominerals inside, [1,25,29] which always leads to the incorporation of the biomacromolecules.…”

“…The morphology of these building blocks can strongly affect the assembly process, and leads to a modulation of mechanical properties and biogenic functions [3,8,14] . Therefore, revealing the mechanisms of morphological evolution in biomineralization can provide new strategies for designing and synthesizing novel materials (e. g., biomedical and structural materials) [14–28] …”

A bicarbonate-rich liquid condensed phase in non-saturated solutions in the absence of divalent cations

“…The mechanism by which this liquid-condensed precursor phase actually forms, is unclear; both the attraction of ions through strong divalent positive-to-negative attractions and the role of water solvation properties, through binodal and spinodal separation mechanisms, have been proposed and are being actively debated (Faatz et al, 2005;Rieger et al, 2007;Dorvee and Veis, 2013;Wallace et al, 2013;Sebastiani et al, 2016). Similar experiments performed elsewhere using photodecarboxylation reactions of a Ketoprofen compound demonstrate the ability to produce stable HCO3moieties (Menichetti et al, 2021). In many of these discussions, the LCP phase is described as a transient precursor, driven by ion charge attraction (between Ca 2+ and CO 3 2for the calcium carbonate system), which exists only briefly before formation of solid, stable, CaCO 3 nuclei.…”