Antibody-conjugated soybean oil-filled calcium phosphate nanoshells for targetted delivery of hydrophobic molecules

Hollow mesoporous hydroxyapatite nanostructures; smart nanocarriers with high drug loading and controlled releasing features

We report the development of effective drug loaded nanocarriers to combat multidrug resistant infection especially in case of osteomyelitis. The hollow mesoporous hydroxyapatite nanoparticles (hmHANPs) and solid/non-hollow hydroxyapatite nanoparticles (sHANPs) were synthesized by core-shell and co-precipitation techniques respectively. High encapsulation of the drug (ciprofloxacin) was observed in hmHANPs as compared to sHANPs, which may be due to the hollow porous structure of hmHANPs. These nanoparticles were characterized by scanning electron microscope (FESEM), N₂ adsorption/desorption, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). Approximately 80% of the encapsulated drug was released at pH 4.5 within 5 days in case of hmHANPs while at pH 7.4, a sustained drug release profile was obtained and only 48.73% of the drug was released after 9 days. The results of kinetic drug release revealed that drug loaded hmHANPs showed fickian diffusion and anomalous drug diffusion mechanism at pH 4.5 and 7.4 respectively. Owing to their porous structure and high drug loading capacity, hmHANPs showed enhanced antibacterial activity against Staphylococcus aureus and Escherichia coli (drug resistant strains of osteomyelitis) in comparison to that with sHANPs. In addition, hmHANPs showed a pH sensitive drug release profile, high surface area (105.33 m²/g) with increased pore volume (0.533 cm³/g) and superior antimicrobial activity against osteomyelitis as compared to sHANPs.

Fluorophore-doped calcium phosphate nanoparticles for non-toxic biomedical applications

Cell viability assay showing absence of toxicity in cells treated with calcium phosphate nanoparticles, without (CP) and with (CP-CH) chitosan coating.

Synthesis and release of trace elements from hollow and porous hydroxyapatite spheres

It is known that organic species regulate fabrication of hierarchical biological forms via solution methods. However, in this study, we observed that the presence of inorganic ions plays an important role in the formation and regulation of biological spherical hydroxyapatite formation. We present a mineralization method to prepare ion-doped hydroxyapatite spheres with a hierarchical structure that is free of organic surfactants and biological additives. Porous and hollow strontium-doped hydroxyapatite spheres were synthesized via controlling the concentration of strontium ions in a calcium and phosphate buffer solution. Similarly, fluoride and silicon-doped hydroxyapatite spheres were synthesized. While spherical particle formation was attainable at low and high temperature for Sr-doped hydroxyapatite, it was only possible at high temperature in the F/Si-doped system. The presence of inorganic ions not only plays an important role in the formation and regulation of biological spherical hydroxyapatite, but also could introduce pharmaceutical effects as a result of trace element release. Such ion release results showed a sustained release with pH responsive behavior, and significantly influenced the hydroxyapatite re-precipitation. These ion-doped hydroxyapatite spheres with hollow and porous structure could have promising applications as bone/tooth materials, drug delivery systems, and chromatography supports.

Nanosized and nanocrystalline calcium orthophosphates

Recent developments in biomineralization have already demonstrated that nanosized crystals and particles play an important role in the formation of hard tissues of animals. Namely, it is well established that the basic inorganic building blocks of bones and teeth of mammals are nanosized and nanocrystalline calcium orthophosphates in the form of apatites. In mammals, tens to hundreds nanocrystals of a biological apatite have been found to be combined into self-assembled structures under the control of bioorganic matrixes. Therefore, application and prospective use of the nanosized and nanocrystalline calcium orthophosphates for a clinical repair of damaged bones and teeth are also well known. For example, greater viability and better proliferation of various types of cells have been detected on smaller crystals of calcium orthophosphates. Thus, the nanosized and nanocrystalline forms of calcium orthophosphates have great potential to revolutionize the hard tissue-engineering field, starting from bone repair and augmentation to controlled drug delivery systems. This paper reviews the current state of art and recent developments of various nanosized and nanocrystalline calcium orthophosphates, starting from synthesis and characterization to biomedical and clinical applications. The review also provides possible directions for future research and development.

Preparation and sustained-release property of triblock copolymer/calcium phosphate nanocomposite as nanocarrier for hydrophobic drug

The P123/ACP nanocomposite with sizes less than 100 nm consisting of triblock copolymer P123 and amorphous calcium phosphate (ACP) has been prepared by using an aqueous solution containing CaCl2, (NH4)3PO4, and P123 at room temperature. The P123/ACP nanocomposite is used as the nanocarrier for hydrophobic drug ibuprofen, based on the combined advantages of both amphiphilic block copolymer and calcium phosphate delivery system. The P123/ACP nanocomposite has a much higher ibuprofen loading capacity (148 mg/g) than the single-phase calcium phosphate nanostructures. The drug release percentage of the P123/ACP nanocomposite in simulated body fluid reaches about 100% in a period of 156 h, which is much slower than that of single-phase calcium phosphate nanostructures. It is expected that the P123/ACP nanocomposite is promising for the application in the controlled delivery of hydrophobic drugs.

Nanodimensional and Nanocrystalline Apatites and Other Calcium Orthophosphates in Biomedical Engineering, Biology and Medicine

Recent developments in biomineralization have already demonstrated that nanosized particles play an important role in the formation of hard tissues of animals. Namely, the basic inorganic building blocks of bones and teeth of mammals are nanodimensional and nanocrystalline calcium orthophosphates (in the form of apatites) of a biological origin. In mammals, tens to hundreds nanocrystals of a biological apatite were found to be combined into self-assembled structures under the control of various bioorganic matrixes. In addition, the structures of both dental enamel and bones could be mimicked by an oriented aggregation of nanosized calcium orthophosphates, determined by the biomolecules. The application and prospective use of nanodimensional and nanocrystalline calcium orthophosphates for a clinical repair of damaged bones and teeth are also known. For example, a greater viability and a better proliferation of various types of cells were detected on smaller crystals of calcium orthophosphates. Thus, the nanodimensional and nanocrystalline forms of calcium orthophosphates have a great potential to revolutionize the field of hard tissue engineering starting from bone repair and augmentation to the controlled drug delivery devices. This paper reviews current state of knowledge and recent developments of this subject starting from the synthesis and characterization to biomedical and clinical applications. More to the point, this review provides possible directions of future research and development.

Calcium phosphate nanocomposite particles for in vitro imaging and encapsulated chemotherapeutic drug delivery to cancer cells

Paradigm-shifting modalities to more efficiently deliver drugs to cancerous lesions require the following attributes: nanoscale-size, targetability, and stability under physiological conditions. Often, these nanoscale drug delivery vehicles are limited due to agglomeration, poor solubility, or cytotoxicity. Thus, we have designed a methodology to encapsulate hydrophobic antineoplastic chemotherapeutics within a 20-30 nm diameter, pH-responsive, nonagglomerating, nontoxic calcium phosphate nanoparticle matrix. In the present study, we report on calcium phosphate nanocomposite particles (CPNPs) that encapsulate both fluorophores and chemotherapeutics, are colloidally stable in physiological solution for an extended time at 37 degrees C and can efficaciously deliver hydrophobic antineoplastic agents, such as ceramide, in several cell model systems.