Chitin and its deacetylated derivative chitosan are natural polymers composed of randomly distributed � -(1-4)- linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). Chitin is insoluble in aqueous media while chitosan is soluble in acidic conditions due to the free protonable amino groups present in the D-glucosamine units. Due to their natural origin, both chitin and chitosan can not be defined as a unique chemical structure but as a fam- ily of polymers which present a high variability in their chemical and physical properties. This variability is related not only to the origin of the samples but also to their method of preparation. Chitin and chitosan are used in fields as different as food, biomedicine and agriculture, among others. The success of chitin and chitosan in each of these specific applica- tions is directly related to deep research into their physicochemical properties. In recent years, several reviews covering different aspects of the applications of chitin and chitosan have been published. However, these reviews have not taken into account the key role of the physicochemical properties of chitin and chitosan in their possible applications. The aim of this review is to highlight the relationship between the physicochemical properties of the polymers and their behaviour. A functional characterization of chitin and chitosan regarding some biological properties and some specific applications (drug delivery, tissue engineering, functional food, food preservative, biocatalyst immobilization, wastewater treatment, molecular imprinting and metal nanocomposites) is presented. The molecular mechanism of the biological properties such as biocompatibility, mucoadhesion, permeation enhancing effect, anticholesterolemic, and antimicrobial has been up- dated.

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Functional Characterization of Chitin and Chitosan

Nano-biocomposites: Biodegradable polyester/nanoclay systems

Adsorption of chromium (VI) by ethylenediamine-modified cross-linked magnetic chitosan resin: isotherms, kinetics and thermodynamics.

The detection of specific proteins as biomarkers of disease, health status, environmental monitoring, food quality, control of fermenters and civil defence purposes means that biosensors for these targets will become increasingly more important. Among the technologies used for building specific recognition properties, molecularly imprinted polymers (MIPs) are attracting much attention. In this critical review we describe many methods used for imprinting recognition for protein targets in polymers and their incorporation with a number of transducer platforms with the aim of identifying the most promising approaches for the preparation of MIP-based protein sensors (277 references).

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The rational development of molecularly imprinted polymer-based sensors for protein detection.

Molecularly imprinted polymers for the recognition of proteins: the state of the art.

Adsorptive separation of hemoglobin by molecularly imprinted chitosan beads.

Structure and mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/clay nanocomposites

Chemically modified chitosan beads as matrices for adsorptive separation of proteins by molecularly imprinted polymer

Core–shell structured particles, which comprise the rubbery core and glassy layers, were prepared by emulsifier-free emulsion polymerization of poly(n-butyl acrylate/methyl methacrylate)/polystyrene [P(n-BA/MMA)/PS]. The particle diameter was about 0.22 μm, and the rubbery core was uncrosslinked and lightly crosslinked, respectively. The smaller core–shell structured particle–toughened PS blends were investigated in detail. The dynamic mechanical behavior and observation by scanning electron microscopy of the modified blend system with core–shell structured particles indicated good compatibility between PS and the particles, which is the necessary qualification for an effective toughening modifier. Notched-impact strength and related mechanical properties were measured for further evaluation of the toughening efficiency. The notched-impact strength of the toughened PS blends with uncrosslinked particles reached almost sixfold higher than that of the untoughened PS when 15 phr of the core–shell structured particles was added. For the crosslinked particles the toughening effect for PS was not obvious. The toughening mechanism for these smaller particles also is discussed in this article. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1290–1297, 2003

Toughening modification of PS with n-BA/MMA/styrene core-shell structured copolymer from emulsifier-free emulsion polymerization

The core–shell structured particles which comprise rubbery and glassy layers were prepared by emulsifier-free emulsion polymerization of poly(n-butyl acrylate/methyl methacrylate)/poly(methyl methacrylate/n-butyl acrylate) [P(BA/MMA)/P(MMA/BA)]. The core–shell structured particle toughened PVC blends were investigated in detail. Impact strength, elongation at break and the related mechanical properties were measured for further evaluation of the toughening efficiency. Copyright © 2003 John Wiley & Sons, Ltd.

Guang-Jie Hao

Papers

Adsorptive separation of hemoglobin by molecularly imprinted chitosan beads.

Structure and mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/clay nanocomposites

Chemically modified chitosan beads as matrices for adsorptive separation of proteins by molecularly imprinted polymer

Toughening modification of PS with n-BA/MMA/styrene core-shell structured copolymer from emulsifier-free emulsion polymerization

Influence of core–Shell structured particles on the impact resistance of poly(vinyl chloride)