Chitosan bionanocomposites

Besides the previously mentioned collagen, a wide variety of natural polymers have been involved in the synthesis of bio-nanohybrid materials with potential application in bone repair and dental prostheses. For instance, some recent examples refer to bionanocomposites based on the combination of HAP with alginate [96,97], chitosan [98,99], bovine serum albumin (BSA) [100], sodium caseinate [101], hyaluronic acid [102], silk fibroin [103,104], silk sericin [105], or polylactic add (PLA) [106,107]. These examples illustrate the increasing interest in the subject of HAP-based biohybrid materials, which has led to almost 400 articles appeared in scientific journals in 2006 alone. 

Pandey, S. Mishra S. B., (2011). Organic-inorganic hybrid of chitosan/ organoclay bionanocomposites for hexavalent chromium uptake. Journal of Colloid and Interface Science. Vol. 361, pp. 509-520. 

In recent years, there has been a quest to find alternatives for metallic composites in bone repair. Bionanocomposites that can mimic the structure of bone are of great importance. Biopolymer composites containing collagen, chitosan, and chitin have the desired mechanical and biological... 

Focusing on reinforced polysaccharide films, positively charged chitosan (a linear polysaccharide mainly extracted from shrimp and other crustacean shells) was assembled with sepiolite clay, giving rise to self-supported bionanocomposite films with interesting structural and functional properties. In this study, Darder and co-authors [113] revealed that the association of sepiolite and chitosan resulted in a threefold improvement in the mechanical properties as compared with unmodified... 

The blend created for tissue engineering scaffolds can also be used as a material for drug delivery. Reddy et al7 reported the development of a bone filler and drug delivery vehicle using a bionanocomposite, which was filled with bone morphogenetic protein, which stimulates bone formation. Besides that, a hydro>yapatite/chitosan nanocomposite was used in the controlled release of vitamins from the matrix. The blending of PHAs could also be used in a similar way since they share the same features, such as the biocompatibility and not causing adverse effects, which produce desirable clinical outcomes. Chan et developed P(3HB)/EtC blends with a... 

L.N.M. Ribeiro, A.C.S. Alcintara, M. Darder, P. Aranda, F.M. Araiijo-Moreira, and E. Ruiz-Hitzky, Pectin-coated chitosan-LDH bionanocomposite beads as potential systems for colon-targeted drug delivery, Int. J. Pharmaceut., 463,1-9,2014. 

Shafei AE, Abou-Okeil A (2011) ZnO/carboxymethyl chitosan bionanocomposite to impart antibacterial and UV protection for cotton fabric. Carbohydr Polym 83 920-925 Shaikh S, Birdi A, Qutubuddin S, Lakatosh E, Baskaran H (2(X)7) Controlled release in transdermal pressure sensitive adhesives using organosilicate nanocomposites. Annals Biomed Eng 35 2130-2137... 

Wang Z, Zhou J, Wang X, Zhang N, Sun X, Ma Z (2014) The effects of ultrasonic/microwave assisted treatment on the water vapor barrier properties of soybean protein isolate-based oleic acid/stearic acid blend edible films. Food Hydrocolloids 35 51-58 Wihodo M, Moraru Cl (2013) Physical and chemical methods used to enhance the structure and mechanical properties of protein films a review. J Food Eng 114(3) 292-302 Woehl MA, Canestraro CD, Mikowski A, Sierakowski MR (2010) Bionanocomposites of thermoplastic starch reinforced with bacterial cellulose nanofibers effect of enzymatic treatment on mechanical properties. Carbohydr Polym 80 866-873 Xu YX, Kim KM, Hanna MA, Nag D (2005) Chitosan-starch composite film preparation and characterization. Ind Crops Prod 21 185-192... 

Although chitin can be processed in the form of films, it has been largely used as reinforcement to bionanocomposites. Chitin nanowhiskers have been used to prepare a variety of bionanocomposites with matrices such as natural rubber, PLA, PCL, PVA, silk fibroin, and chitosan [185-194], as will be discussed throughout the text below. 

Chitosan has also been used as a matrix for bionanocomposites with a variety of nanoreinforcements such as chitin, days, and cellulose nanofibrils [189, 196-200]. 

Mathew et al. [196] developed cross-Hnked bionanocomposites using chitosan reinforced with chitin nanocrystals and gluteraldehyde as the cross-linker. These composites were characterized by FTIR, XRD, and atomic force microscopy (AFM). The authors found that cross-hnking and chitin whiskers content were both found to impact the water uptake mechanism. Cross-hnking provided dimensional stabihty in addic medium and significantly decreased the equihbrium water uptake. Moreover, incorporation of chitin nanocrystals provided increased permeation selectivity to chitosan in neutral and addic medium. 

Chitosan-based bionanocomposites with improved properties, namely barrier and mechanical properties, were also prepared by Moura et al. [200] who added chitosan/tripolyphosphate (CS-TPP) nanoparticles to hydroxypropyl methylceUu-lose (HPMC) edible films (Figure 11.14). Samples were characterized by FTIR, TEM, SEM, mechanical properties, water vapor permeability (WVP), and thermal stability. The authors reported that the incorporation of chitosan nanoparticles into the films improved their mechanical and film barrier properties significantly. This behavior was attributed to the chitosan nanoparticles that tend to occupy the empty spaces in the pores of the HPMC matrix, increasing the collapse of the pores and thereby improving film tensile properties and WVP. 

Bionanocomposites using chitosan reinforced with different concentrations of cellulose nanofibers (CNEs) and glycerol as the plasticizer were developed by Azeredo et al. [197]. The effect of reinforcement on tensile properties, WVP, and glass transition temperature was studied. The authors showed that CNFs improved the mechanical and water vapor barrier properties of chitosan films. The bionanocomposite with 15% CNE, plasticized with 18% glycerol, was found to be comparable to some synthetic polymers in terms of strength and stiffness. However, their films had relatively poor HexibiHty and water vapor barrier. 

Figure 11.14 TEM microphotography of chitosan/tripolyphosphate (CS-TPP) nanoparticles used in the hydroxypropyl methylcellulose (HPMC) bionanocomposites [200].

Chitosan/vermiculite (VMT) bionanocomposites were studied by Zhang et al. [199] who prepared their composites by solution mixing of chitosan with three different modified VMTs, viz., hydrochloride (HVMT), sodium (NVMT), and cetyl trimethyl ammonium bromide (OVMT) treated VMT. Wide-angle X-ray diffraction (WAXD), TEM, and TGA were employed in composite characterization. The authors reported that both WAXD and TEM characterization indicated that the silicate layers were dispersed into the chitosan matrix in a disordered array. It was also found that the thermal stabihty of the bionanocomposites was dependent on the clay modification process. The chitosan/HVMT nanocomposites had the best thermal performance, compared to that of neat chitosan, which was attributed to the good dispersion of acid-modified VMT and better interaction between HVMT and chitosan in the bionanocomposites. 

Figure 11.15 Schematic representation of chitosan intercalated in the clay substrate as a bilayer used in bionanocomposite-based sensors [202].

Chitosan has also been used as reinforcement in nanocomposites. Chitosan nanoparticles were used by Kampeerapappun et al. [204] to produce bionanocomposites with cassava starch and MMT nanocomposites. The authors reported that the addition of chitosan, due to its hydrophilicity and ability to attach to the clay surface, played a role in compatibilizing the interface between starch matrix and MMT. As a result, the starch/MMT composite film at low MMT content exhibited an improvement in tensile properties due to a reinforcement effect It was also found that the surface hydrophobicity of the composite film increased with an increase in chitosan content In association with film hydrophobicity, the water vapor transmission rate and moisture absorption were found to decrease with an increase in chitosan content. 

The use of chitosan bionanocomposites with hydroxyapatite has also been reported in the literature as potential biomaterials. Chitosan (CS)/hydroxyapatite (HA) bionanocomposites prepared by in situ hybridization, according to Hu et al. [205] can be potentially applied in internal fixation of bone fractures. Also, Zhang et al. 

El-Sherbiny, I.M., El-Baz, N.M., 2015. A Review on Bionanocomposites Based on Chitosan and Its Derivatives for Biomedical Applications. Eco-Mendly Polymer Nanocomposites. 

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