J Brugnerotto

Bio: J Brugnerotto is an academic researcher from Joseph Fourier University. The author has contributed to research in topics: Polysaccharide & Infrared spectroscopy. The author has an hindex of 3, co-authored 3 publications receiving 1460 citations.

Overview on structural characterization of chitosan molecules in relation with their behavior in solution.

Abstract: This paper concerns the new results obtained on the characterization of chitins and chitosans. Large series of samples was analyzed covering a wide range of water soluble and insoluble materials. The water soluble polymers were obtained by heterogeneous deacetylation and by homogeneous reacetylation. The calibration of IR spectrum was proposed and shown to be valid in all the range of DA. Application of 15 N and C solid state NMR was developed to be able to determine DA even in situ on insoluble natural materials. All the methods proposed give a very coherent set of results, The molecular weight distribution was established by GPC using cationic porous supports and the good solvent earlier proposed 0.3M AcOH/ 0.2M AcONa. The role of the distribution of acetyl groups along the chain is also discussed and analyzed by NMR ; it is demonstrated clearly the difference between homogeneously acetylated samples and heterogeneous samples coming from different routes of preparation. The dependence of Mark-Houwink parameters allowing to relate the intrinsic viscosity with the molecular weight is also briefly reported. In good concordance with experimental data, molecular modeling helps in understanding the role of the N-acetyl group content and distribution on the stiffness of the chains.

Chitin and Chitosan Preparation from Marine Sources. Structure, Properties and Applications

Abstract: This review describes the most common methods for recovery of chitin from marine organisms. In depth, both enzymatic and chemical treatments for the step of deproteinization are compared, as well as different conditions for demineralization. The conditions of chitosan preparation are also discussed, since they significantly impact the synthesis of chitosan with varying degree of acetylation (DA) and molecular weight (MW). In addition, the main characterization techniques applied for chitin and chitosan are recalled, pointing out the role of their solubility in relation with the chemical structure (mainly the acetyl group distribution along the backbone). Biological activities are also presented, such as: antibacterial, antifungal, antitumor and antioxidant. Interestingly, the relationship between chemical structure and biological activity is demonstrated for chitosan molecules with different DA and MW and homogeneous distribution of acetyl groups for the first time. In the end, several selected pharmaceutical and biomedical applications are presented, in which chitin and chitosan are recognized as new biomaterials taking advantage of their biocompatibility and biodegradability.

Functional Characterization of Chitin and Chitosan

Abstract: 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.

Main properties and current applications of some polysaccharides as biomaterials

Abstract: This review concerns the applications of some polysaccharides in the domain of biomaterials and bioactive polymers. Natural polysaccharides from different sources have been studied for a long time, and their main properties are summarized in this paper; some of their derivatives obtained by chemical modification are also described. The main polysaccharides currently used in the biomedical and pharmaceutical domains are chitin and its derivative chitosan, hyaluronan and alginates. Alginates are well known for their property of forming a physical gel in the presence of divalent counterions (Ca, Ba, Sr) whereas carrageenans form a thermoreversible gel; these seaweed polysaccharides are mainly used to encapsulate different materials (cells, bacteria, fungi). Other promising systems are the electrostatic complexes formed when an anionic polysaccharide is mixed with a cationic polysaccharide (e.g. alginate/chitosan or hyaluronan/chitosan). An important development of the applications of polysaccharides can be predicted for the next few years in relation to their intrinsic properties such as biocompatibility and biodegradability in the human body for some of them; they are also renewable and have interesting physical properties (film-forming, gelling and thickening properties). In addition, they are easily processed in different forms such as beads, films, capsules and fibres. Copyright © 2007 Society of Chemical Industry