CaCO3 Microspheres Research Articles

Facile Preparation of Hollow Hydroxyapatite Microspheres

Without any organic additives and metal ions,hollow hydroxyapatite(HAp)microspheres were successfully synthesized using hollow CaCO3 microspheres and Na2HPO4 as reactants. The hollow microspheres were characterized by scanning electron microscopy (SEM), field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). The results showed that the as-prepared HAp was hollow microspheres with diameter of 2-4 μm and were composed of many needle-like particles of 40-60 nm in diameter and 80-200 nm in length. The effects of synthesis conditions, such as reaction temperature, were studied. Furthermore, the reaction temperature has an important influence on the morphology of the hollow HAp microspheres. Based on this result, the formation mechanism of hollow HAp microspheres was discussed preliminarily.

Hemoglobin‐CdTe‐CaCO3@Polyelectrolytes 3D Architecture: Fabrication, Characterization, and Application in Biosensing

AbstractA Hemoglobin‐CdTe‐CaCO3@polyelectrolyte 3D architecture is synthesized by a stepwise layer‐by‐layer method and is further used to fabricate an electrochemistry biosensor. While the calcium carbonate (CaCO3) microsphere acts as an effective host for the loading of cadmium telluride (CdTe) quantum dots due to its channel‐like structure, the polyelectrolyte layers further increase the loading amount and help in the formation of a thick and uniform quantum‐dot “shell”, which not only improves the stability of the spheres in water, but also contributes to the fast and effective direct electron transfer between the protein redox center and the macroscopic electrode. The materials are characterized and compared, and the possible mechanism for the direct electrochemistry phenomenon is hypothesized. Our work not only provides a facile and effective route for the preparation of quantum‐dot‐loaded spheres, but also sets an example of how the structure of functional materials can be tuned and related to their applications. In addition, it is one of the few examples of using CaCO3 microspheres in quantum‐dot loading and biosensing.

The synthesis of hollow CaCO3 microspheres in mixed solutions of surfactant and polymer

In this paper, we report a simple strategy for fabricating hollow CaCO3 microspheres. We employed poly (ethylene glycol) (PEG) and sodium dodecyl sulfate (SDS) in one system, as a template for the controlled growth of hollow CaCO3 microspheres. It suggests that the PEG–SDS complex micelles play a key role in controlling the growth of biominerals. The variation of polymer molecular weight drastically changed the morphology and polymorph of the obtained CaCO3. These results also present a facile route to biomimetic inorganic synthesis.

Base−Acid Equilibria in Polyelectrolyte Systems: From Weak Polyelectrolytes to Interpolyelectrolyte Complexes and Multilayered Polyelectrolyte Shells

We have measured potentiometric titration curves of the weak polyelectrolytes, PAH1 and PAA, interpolyelectrolyte complexes PAH−PAA, PDADMAC−PAA, and PAH−PAA, prepared by mixing of the polyelectrolyte solutions, and multilayered microcapsules made by layer-by-layer adsorption of the same pairs of oppositely charged polyelectrolytes onto CaCO3 microspheres(PAH/PAA)5, (PDADMAC/PAA)5, and (PAH/PSS)5. The data were analyzed within the frame of an Ising model taking into account the nearest-neighbor interaction between proton binding sites. The anticooperative character of proton binding with PAH (cooperativity parameter q = 0.13) was shown to become a highly cooperative process in the interpolyelectrolyte complex PAH−PSS and multilayered microcapsules (PAH/PSS)5, q ≈ 2−3. The cooperativity of the process is increased also for complexes PDADMAC−PAA and PAH−PAA and for multilayered shells (PDADMAC/PAA)5 and (PAH/PAA)5; however, the cooperativity parameter q remains below unity for the PDADMAC−PAA system or a li...