Continuous-Flow Precipitation of Hydroxyapatite at 37 °C in a Meso Oscillatory Flow Reactor

Rapid Flow Synthesis of a Biomimetic Carbonate Apatite as an Effective Drug Carrier

A facile synthesis of apatite nanocrystals analogous to bioapatites with increased biocompatibility and biodegradability can remedy the shortcomings of the widely applied synthetic hydroxyapatite (HAp) for bone defect treatment. Here, we propose an expeditious synthesis method to develop a biomimetic B-type carbonate apatite (CAp) with a simple capillary microfluidic device at room temperature. The process not only eliminates fluctuations with the addition of carbonate but also produces safe CAp drug carriers through simultaneous alendronate incorporation to the CAp structure. CAp displayed superior mineralization on osteoblast-like MG-63 cells when compared with HAp and HAp drug carriers that were produced using identical methods. Furthermore, alendronate-incorporated CAp drug carriers potentially displayed higher cancer cell suppression when applied to breast cancer cells attached to the bone tissue model, which signifies enhanced cancer metastasis to bone suppression due to the likelihood of increased alendronate release of CAp owing to its faster dissolution. Overall, our results may provide promising opportunities for enhanced clinical CAp application for bone defect treatment, particularly for bone loss and cancer to bone metastasis.

Optimal Operation of an Oscillatory Flow Crystallizer: Coupling Disturbance and Stability

In the process of industrial crystallization, it is always difficult to balance the secondary nucleation rate and metastable zone width (MSZW). Herein, we report an experimental and numerical study for the cooling crystallization of paracetamol in an oscillatory flow crystallizer (OFC), finding the optimal operating conditions for balancing the secondary nucleation rate and MSZW. The results show that the MSZW decreases with the increase of oscillation Reynolds number (Re _o). Compared to the traditional stirring system, the OFC has an MSZW three times larger than that of the stirring system under a similar power density of consumption. With the numerical simulation, the OFC can produce a stable space environment and instantaneous strong disturbance, which is conducive to the crystallization process. Above all, a high Re _o is favorable to produce a sufficient nucleation rate, which may inevitably constrict the MSZW to a certain degree. Then, the optimization strategy of the operating parameter (Re _o) in the OFC is proposed.

Directional growth of octacalcium phosphate using micro-flow reactor mixing and subsequent aging

Well-defined belt-shaped particles of octacalcium phosphate were prepared by mixing aqueous solutions of calcium acetate and that of sodium phosphate monobasic with the aid of a micro-flow reactor. Higher crystallinity and narrower particle size distribution were achieved by the micro-flow reactor if compared with the results of the batch reaction using the same solutions. The width of the belt was controlled by the mixing temperature (0.8 and 2.3 μm for the preparation at 50 and 70 °C, respectively). Post mixing aging at 50 °C, resulted in the directional growth of belt-shaped particles to obtain particles with the length of 17 μm (aspect ratio of 53). XRD and TEM analysis indicated that the micro-flow reactor could separate nucleation and growth allowing preferential growth along the a-direction.

Well-defined octacalcium phosphate particles with varied size and aspect ratio were prepared by a micro-flow reactor mixing and subsequent aging in different temperature and aging time.

Calcium Phosphate Nanoparticle Precipitation by a Continuous Flow Process: A Design of Experiment Approach

Calcium phosphate nanoparticles (CaP NPs) are an efficient class of nanomaterials mainly used for biomedical applications but also very promising in other sectors such as cosmetics, catalysis, water remediation, and agriculture. Unfortunately, as in the case of other nanomaterials, their wide application is hindered by the difficulty to control size, morphology, purity and degree of particle aggregation in the translation from laboratory to industrial scale production that is usually carried out in batch or semi-batch systems. In this regard, the use of continuous flow synthesis can help to solve this problem, providing more homogenous reaction conditions and highly reproducible synthesis. In this paper, we have studied with a design of experiment approach the precipitation of citrate functionalized CaP NPs aided by sonication using a continuous flow wet chemical precipitation, and the effect of some of the most relevant process factors (i.e., reactant flow rate, sonication amplitude, and maturation time) on the physico-chemical properties of the NPs were evaluated. From the statistical data analysis, we have found that CaP NP dimensions are influenced by the reactor flow rate, while the crystalline domain dimensions and product purity are influenced by the maturation process. This work provides a deeper understanding of the relationships between reaction process factors and CaP NP properties, and is a relevant contribution for the scale-up production of CaP NPs for nanomedical or other applications.

Low-Temperature Continuous Flow Synthesis of Metal Ammonium Phosphates

The synthesis of the high performance inorganic materials essential to the quality of modern day life is hindered by traditionalist attitudes and reliance on outdated methods such as batch syntheses. While continuous flow methods have been extensively adopted in pharmaceutical circles, they remain largely unexplored for the preparation of inorganic compounds, despite higher efficiency, safety and versatility. In this publication, we demonstrate a step-change for the synthesis of metal ammonium phosphates through conversion of the extant batch process to a low-temperature continuous regime, exhibiting a tenfold increase in throughput combined with a significant decrease in particle size.