Chitin and Chitosan in Selected Biomedical Applications

Biocompatibility and osteogenesis of biomimetic nano-hydroxyapatite/polyamide composite scaffolds for bone tissue engineering.

The first part of this review looks at the fundamental properties of hydroxyapatite (HAP), the basic mineral constituent of mammalian hard tissues, including the physicochemical features that govern its formation by precipitation. A special emphasis is placed on the analysis of qualities of different methods of synthesis and of the phase transformations intrinsic to the formation of HAP following precipitation from aqueous solutions. This serves as an introduction to the second part and the main subject of this review, which relates to the discourse regarding the prospects of fabrication of ultrafine, nanosized particles based on calcium phosphate carriers with various therapeutic and/or diagnostic agents coated on and/or encapsulated within the particles. It is said that the particles could be either surface-functionalized with amphiphiles, peptides, proteins, or nucleic acids or injected with therapeutic agents, magnetic ions, or fluorescent molecules. Depending on the additive, they could be subsequently used for a variety of applications, including the controlled delivery and release of therapeutic agents (extracellularly or intracellularly), magnetic resonance imaging and hyperthermia therapy, cell separation, blood detoxification, peptide or oligonucleotide chromatography and ultrasensitive detection of biomolecules, and in vivo and in vitro gene transfection. Calcium phosphate nanoparticles as carriers of therapeutic agents that would enable a controlled drug release to treat a given bone infection and at the same be resorbed in the body so as to regenerate hard tissue lost to disease are emphasized hereby as one of the potentially attractive smart materials for the modern medicine.

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Nanosized hydroxyapatite and other calcium phosphates: chemistry of formation and application as drug and gene delivery agents.

Silicone rubber’s special features such as “organosiloxanes polymer” has been originated from its unique molecular structure that they carry both inorganic and organic properties unlike other organic rubbers. In other words, due to the Si–O bond of silicone rubber and its inorganic properties, silicone rubber was superior to ordinary organic rubbers in terms of heat resistance, chemical stability, electrical insulating, abrasion resistance, weatherability and ozone resistance. With these unique characteristics, silicone rubber has been widely used to replace petrochemical products in various industries like aerospace, munitions industry, automobile, construction, electric and electronics, medical and food processing industry. Recently, these scopes of silicone applications have been expanding at a great speed by the demand of industries that want more reliable elastomer. This paper reviews on synthesis, general properties, applications and nanocomposites of silicone rubber.

A Review on Silicone Rubber

In recent years, significant development has been achieved in the construction of artificial bone with ceramics, polymers and metals. Nano-hydroxyapatite (nHA) is widely used bioceramic material for bone graft substitute owing to its biocompatibility and osteoconductive properties. nHA with chitin, chitosan, collagen, gelatin, fibrin, polylactic acid, polycaprolactone, poly(lactic-co-glycolic) acid, polyamide, polyvinyl alcohol, polyurethane and polyhydroxybutyrate based composite scaffolds have been explored in the present review for bone graft substitute. This article further reviews the preparative methods, chemical interaction, biocompatibiity, biodegradation, alkaline phosphatase activity, mineralization effect, mechanical properties and delivery of nHA-based nanocomposites for bone tissue regeneration. The nHA based composite biomaterials proved to be promising biomaterials for bone tissue engineering.

Nano-hydroxyapatite composite biomaterials for bone tissue engineering--a review.

Preparation and properties of nano-hydroxyapatite/chitosan/carboxymethyl cellulose composite scaffold

Preparation and characterization of nano-hydroxyapatite/silicone rubber composite

Nano-hydroxyapatite (n-HA)/chitosan (CS)/konjac glucomannan (KGM) composite was prepared by coprecipitation method and investigated by thermal gravitivity/differentiate thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, inductively coupled plasma emission spectroscopy, scanning electron microscopy, and energy dispersive X-ray analyzer. The analyses showed that the three phases of n-HA, CS, and KGM combined closely to each other. Further, in vitro tests were conducted to investigate the degradation and bioactivity of the composite. During immersion in simulated body fluid (SBF), pores appeared and a new substance containing Ca and P formed on the surface of the composite. Also, the concentration of Ca and P in SBF changed and weight loss of the composite was observed during time. The composite revealed a high degradation in SBF. Evidently, the new composite has a potential to be used as a carrier of implantable drug delivery system. The biodegradation rate and route could be different from CS and KGM, which will provide an opportunity to control the degradation rate or drug releasing rate by simply adjusting the ratio of CS and KGM.

Preparation and characterization of nano‐hydroxyapatite/chitosan/konjac glucomannan composite

Fabrication and property of chitosan film carrying ethyl cellulose microspheres

To compare with the human cortical bone, the biomimetic properties of nano-hydroxyapatite/polyamide 66 composite (n-HA/PA66) were preliminarily studied qualitatively and quantitatively with TEM, XRD in crystal morphology, phase composition and crystal structure. A series of structure parameters such as cell lattice parameters (a and c), mean crystallite size and micro-strain were calculated to characterize quantitatively the microstructure of n-HA/PA66 and human cortical bone at the atomic level. The results show that n-HA/PA66 is a good biomimetic biomaterial. But there still are some differences between n-HA/PA66 and human cortical bone. Compared to human cortical bone, the crystal microstructure of n-HA/PA66 is denser, the crystal lattice of n-HA is more perfect and the distortion of crystal lattice decreases.

Yubao Li

Papers

Preparation and properties of nano-hydroxyapatite/chitosan/carboxymethyl cellulose composite scaffold

Preparation and characterization of nano-hydroxyapatite/silicone rubber composite

Preparation and characterization of nano‐hydroxyapatite/chitosan/konjac glucomannan composite

Fabrication and property of chitosan film carrying ethyl cellulose microspheres

Study on the Biomimetic Properties of Bone Substitute Material: Nanohydroxyapatite/Polyamide 66 Composite