This paper reviews the past, present, and future of the hydroxyapatite (HAp)-based biomaterials from the point of view of preparation of hard tissue replacement implants. Properties of the hard tissues are also described. The mechanical reliability of the pure HAp ceramics is low, therefore it cannot be used as artificial teeth or bones. For these reasons, various HAp-based composites have been fabricated, but only the HAp-coated titanium alloys have found wide application. Among the others, the microstructurally controlled HAp ceramics such as fibers/whiskers-reinforced HAp, fibrous HAp-reinforced polymers, or biomimetically fabricated HAp/collagen composites seem to be the most suitable ceramic materials for the future hard tissue replacement implants.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0884291400042527

Processing and properties of hydroxyapatite-based biomaterials for use as hard tissue replacement implants

Controlled release of food ingredients at the right place and the right time is a key functionality that can be provided by microencapsulation A timely and targeted release improves the effectiveness of food additives, broadens the application range of food ingredients and ensures optimal dosage, thereby improving cost-effectiveness for the food manufacturer Reactive, sensitive or volatile additives (vitamins, cultures, flavors, etc) can be turned into stable ingredients through microencapsulation With carefully fine-tuned controlled release properties, microencapsulation is no longer just an added value technique, but the source of totally new ingredients with matchless properties

Microencapsulation: industrial appraisal of existing technologies and trends

Incorporation of bioactive compounds–such as vitamins, probiotics, bioactive peptides, and antioxidants etc.–into food systems provide a simple way to develop novel functional foods that may have physiological benefits or reduce the risks of diseases. As a vital macronutrient in food, proteins possess unique functional properties including their ability to form gels and emulsions, which allow them to be an ideal material for the encapsulation of bioactive compounds. Based on the knowledge of protein physical–chemistry properties, this review describes the potential role of food proteins as substrate for the development of nutraceutical delivery systems in the form of hydrogel, micro-, or nano- particles. Applications of these food protein matrices to protect and delivery-sensitive nutraceutical compounds are illustrated, and the impacts of particle size on release properties are emphasized.

Food protein-based materials as nutraceutical delivery systems

We describe an emulsion-based technique that allows the assembly of colloid particles into microstructured or multicomponent clusters (“supraparticles”). The particles are gathered, assembled, and fixed together in the restricted, colloid-size 2D or 3D space provided by emulsion droplets. The process is carried out by multiple modification of the colloid interactions within the particle/droplet system“interaction-tailored colloid assembly”. In the first paper of the series we provide a general description of the method. Then we present the data on the assembly of negatively charged (sulfate) or positively charged (amidine) latexes into ordered hollow spherical supraparticles. The following steps are included in the assembly schemes:  (1) modification of latex surface charge and properties, so the microspheres are able to adsorb on the droplet surfaces but without homocoagulation; (2) adsorption and structure formation around the emulsion drops (at this stage the interfacial mobility of the particles is of...

Assembly of Latex Particles by Using Emulsion Droplets as Templates. 1. Microstructured Hollow Spheres

The molecular basis of moisture effects on the physical and chemical stability of drugs in the solid state

Preparation of egg albumin microcapsules and microspheres.

Preparation of monolayer particle coated powder by the dry impact blending process utilizing mechanochemical treatment

Polyphthalamide microcapsules were prepared by the interfacial polycondensation reactions between each of 1, 6-hexamethylenediamine and diethylenediamine and each of o-, m-, and p-phthaloyl dichlorides under various conditions. The size and size distribution of the microcapsules formed were determined and the factors affecting them were of studied. Favorable conditions were suggested to obtain the microcapsules of uniform size in a high yield.

Studies on Microcapsules. II. Preparation of Polyphthalamide Microcapsules

New hybrid powders have been produced by the dry processing of six drugs (oxyphenbutazone, prednisolone, theophylline, indomethacin, phenacetin and aspirin), with potato starch used as a core material, by means of an electric mortar and a powder surface reforming system designed to produce hybrid powders. The hybrid powders obtained immediately after production differed in their structure from interactive mixtures. With the hybrid powders the drug was spread on the surface of the core particle by friction and collision that occurred in the dry process, but with interactive mixtures the drug simply adhered as intact particles to the surface of diluent particles. Scanning electron microscopy and powder X-ray diffractometry indicated that the mechanochemical phenomenon was essential for the production of the hybrid powders. With time, a shape change in the adhering drug was observed as a relaxation process took place, with recrystallization resulting from the release of accumulated energy. The change with time might depend upon the method of producing powders and the physical properties of the drug used, e.g. the smooth layer of indomethacin produced by the powder surface reforming system reverted to fine particles tightly adhering to the starch surface, though no change was observed with prednisolone.

Masumi Koishi

Papers

Preparation of egg albumin microcapsules and microspheres.

Preparation of monolayer particle coated powder by the dry impact blending process utilizing mechanochemical treatment

Studies on Microcapsules. II. Preparation of Polyphthalamide Microcapsules

Preparation of drug-diluent hybrid powders by dry processing.

Development of Sustained-Release Formulation of Chlorpheniramine Maleate Using Powder-Coated Microsponge Prepared by Dry Impact Blending Method