Yolk @ cage-Shell Hollow Mesoporous Monodispersion Nanospheres of Amorphous Calcium Phosphate for Drug Delivery with High Loading Capacity

Sol-gel synthesis of amorphous calcium phosphate nanoparticles in brown rice substrate and assessment of their cytotoxicity and antimicrobial activities

OBJECTIVE

This study intended to perform a synthesizing procedure for amorphous calcium phosphate (ACP) through a green template by the usage of brown rice (BR).

MATERIALS AND METHODS

ACP nanoparticles were obtained by application of a sol-gel method and comprehensively characterized using X-ray powder diffraction (XRD), zeta potential, fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), and atomic force microscopy (AFM). Cytotoxic activity of ACP was evaluated in human epithelial type 2 (HEp-2) cell lines. The antibacterial effects of nanoparticles were appraised against Gram-positive Streptococcus mutans and Enterococcus faecalis.

RESULTS

The procedures for the evaluation of the characterization outcomes, dispersion, and stability of our product were confirmed by observing the smooth and uniformed surfaces of ACP. The zeta potential value of the synthesized sample was -22 mV, which indicates its acceptable stable condition caused by electrostatic repulsion. The cytotoxicity of the ACP nanoparticles was investigated in HEp-2 cells, and results showed no cytotoxicity for the synthesized nanoparticles. Also, the obtained minimum inhibitory concentration (MIC) of ACP nanoparticles in opposition to S. mutans and E. faecalis was 15 and 20 µg/ml, respectively, indicating the resistance of E. faecalis in comparison to S. mutans and MBC for synthesized nanoparticles against S. mutans and E. faecalis strains was 20 and 25 µg/ml.

CONCLUSION

The present study showed that this compound has no toxicity on the examined cell line. Also, the antibacterial properties of the synthesized ACP were approved by the obtained data, which enables the application of this material for therapeutic purposes in the pharmaceutical industry.

Deposition of non-porous calcium phosphate shells onto liquid filled microcapsules

The efficient encapsulation of small molecule active ingredients has been a challenge for many decades across many commercial applications. Recently, successful attempts to address this issue have included deposition of thin metal shells onto liquid filled polymer microcapsules or emulsion droplets to provide an impermeable barrier to diffusion. In this work we have developed a novel method to protect small molecule active ingredients by deposition of thin mineral shells. Platinum nanoparticles are used to catalyse and direct growth of a calcium phosphate shell onto liquid filled polymer microcapsules under various reaction conditions. Findings indicate that a non-porous protective shell is formed on the majority of the microcapsule population, with small concentrations of the core material being released only from those microcapsules with defects, over a 7 days period, when conducting forced release studies into a solvent for the core oil. The resulting microcapsules show no significant cell toxicity when exposed to HEK 293 cells for 72 h.

Organic Phosphorous and Calcium Source Induce the Synthesis of Yolk-Shell Structured Microspheres of Calcium Phosphate with High-Specific Surface Area: Application in HEL Adsorption

Yolk-shell-structured calcium phosphate microspheres have a great potential for medical applications due to their excellent physicochemical properties and biocompatibility. However, developing a yolk-shell-structured calcium phosphate with high adsorption capability remains a challenge. Herein, a porous yolk-shell-structured microsphere (ATP-CG) of calcium phosphate with high-specific surface area [SBET = 143 m2 g-1, which is approximately three times as high as that of ATP-CL microspheres synthesized by replacing calcium source with calcium L-lactate pentahydrate (CL)] was successfully synthesized by using adenosine 5'-triphosphate disodium salt (ATP) as the phosphorous source and calcium gluconate monohydrate (CG) as calcium source through a self-templating approache. The influences of molar ratio of Ca to P (Ca/P), hydrothermal temperature, and time on the morphology of ATP-CG microspheres were also investigated. It is found that the organic calcium source and organic phosphorous source play a vital role in the formation of yolk-shell structure. Furthermore, a batch of adsorption experiments were investigated to illuminate the adsorption mechanism of two kinds of yolk-shell-structured microspheres synthesized with different calcium sources. The results show that the adsorption capacity of ATP-CG microspheres (332 ± 36 mg/g) is about twice higher than that of ATP-CL microspheres (176 ± 33 mg/g). Moreover, the higher-specific surface area caused by the calcium source and unique surface chemical properties for ATP-CG microspheres play an important role in the improvement of HEL adsorption capability. The study indicates that the as-prepared yolk-shell-structured microsphere is promising for application in drug delivery fields and provides an effective approach for improving drug adsorption capability.

Rational design of yolk–shell nanostructures for drug delivery

The recent progress in yolk–shell nanoparticles (YSNPs) as a new class of hollow nanostructures applied for drug delivery.

3D Printed Polyvinyl Alcohol Tablets with Multiple Release Profiles

The aim of this study was to explore the feasibility of using different 3D printed internal geometries as tablet formulations to obtain controlled release profiles. In order to obtain controllable release profiles, three types of tablet models (Cylinder, Horn and Reversed Horn) with controlled structures were designed. The cylinder model shows a constant release profile and can keep the drug concentration within a certain range. The horn model exhibits an increasing release profile, which is suitable for the patients who have the drug resistance in the course of medication. The reversed horn model has a decreasing release profile that would be applied to hypertension cure. Furthermore, three types of tablets were fabricated successfully by a fused deposition modeling three-dimensional (3D) printer and injected with paracetamol (APAP) -containing gels. The results of in vitro drug release demonstrate that tablets with three kinds of structures can produce constant, gradually increasing, and gradually decreasing release profiles, respectively. The release attributes can be controlled by using different 3D printed geometries as tablet formulations. More importantly, there are no residues after dissolution. The method of preparing customized tablets with distinguished release profiles presented in this study has the promising potential in the fabrication of patient-tailored medicines.

Nanostructured Calcium-based Biomaterials and their Application in Drug Delivery

In the past several decades, various types of nanostructured biomaterials have been developed. These nanostructured biomaterials have promising applications in biomedical fields such as bone repair, tissue engineering, drug delivery, gene delivery, antibacterial agents, and bioimaging. Nanostructured biomaterials with high biocompatibility, including calcium phosphate, hydroxyapatite, and calcium silicate, are ideal candidates for drug delivery. This review article is not intended to offer a comprehensive review of the nanostructured biomaterials and their application in drug delivery but rather presents a brief summary of the recent progress in this field. Our recent endeavors in the research of nanostructured biomaterials for drug delivery are also summarized. Special attention is paid to the synthesis and properties of nanostructured biomaterials and their application in drug delivery with the use of typical examples. Finally, we discuss the problems and future perspectives of nanostructured biomaterials in the drug delivery field.

Preparation of porous calcium phosphate microspheres with phosphate-containing molecules at room temperature for drug delivery and osteogenic differentiation

Calcium phosphate (CaP) has similar chemical properties to those of the inorganic component of human bone tissue, for potential application in drug delivery for the chemotherapy of osteosarcoma. In this work, CaP with a porous microsphere structure has been synthesized using fructose-1,6-bisphosphate (FBP) as the phosphorus source by a simple wet-chemical strategy at room temperature. The CaP porous microspheres, as an organic–inorganic hybrid nano-platform, exhibit good doxorubicin (Dox) loading capacity, and Dox-loading CaP, enhancing the in vitro chemotherapy of osteosarcoma cells. The CaP porous microspheres show high biocompatibility, and induce the osteogenic differentiation of MC3T3-E1. These results indicate that the CaP porous microspheres reported in this study are promising for application as an anti-osteosarcoma drug carrier and osteoinductive material for bone regeneration in the treatment of osteosarcoma.

Porous calcium phosphate microspheres were prepared at room temperature, and displayed potential for application in the chemotherapy of osteosarcoma and osteogenic differentiation.

Fabrication of Yolk-Shell Cu@C Nanocomposites as High-Performance Catalysts in Oxidative Carbonylation of Methanol to Dimethyl Carbonate

A facile way was developed to fabricate yolk-shell composites with tunable Cu cores encapsulated within hollow carbon spheres (Cu@C) with an average diameter about 210 nm and cavity size about 80 nm. During pyrolysis, the confined nanospace of hollow cavity ensures that the nucleation-and-growth process of Cu nanocrystals take place exclusively inside the cavities. The size of Cu cores can be easily tuned from 30 to 55 nm by varying the copper salt concentration. By deliberately creating shell porosity through KOH chemical activation, at an optimized KOH/HCS mass ratio of 1/4, the catalytic performance for the oxidative carbonylation of methanol to dimethyl carbonate (DMC) of the activated sample is enhanced remarkably with TOF up to 8.6 h^-1 at methanol conversion of 17.1%. The activated yolk-shell catalyst shows promising catalytic properties involving the reusability with slight loss of catalytic activity and negligible leaching of activated components even after seven recycles, which is beneficial to the implementation of clean production for the eco-friendly chemical DMC thoroughly.