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An amphiphilic derivative of chitosan containing quaternary ammonium and myristoyl groups, herein named as ammonium myristoyl chitosan (DMCat), was synthesized by reacting glycidyltrimethylammonium chloride (GTMAC) and myristoyl chitosan (DMCh). The success of the modification was confirmed using Fourier-transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopy. The average degrees of alkylation and quaternization ( D Q ¯ ) were determined by using 1H NMR and conductometric titration. The zeta potential of the micelles was higher than 28 mV while its average size and encapsulation efficiency ranged from 280 nm to 375 nm and 68% to 100%, respectively. The in vitro cytotoxicity of the unloaded and curcumin (CUR)-loaded micelles was tested against Caco-2 and HT29-MTX intestinal epithelial cell lines. The results showed no cytotoxic effect from loaded and unloaded micelles as compared to free CUR. In the permeability test, it was observed that both types of micelles, i.e., DMCh and DMCat, improved CUR permeability. Additionally, higher permeability was verified for both systems in Caco-2/HT29-MTX:Raji B because of the mucoadhesive character of chitosan and its ability to open tight junctions. The results indicated that DMCat micelles, due to the physico-chemical, improved characteristics may be a promising carrier to encapsulate CUR aiming cancer therapy.

Chitosan was reacted with monochloroacetic acid at room temperature for different reaction times (3h, 5h, 7h and 10h) and employing two chitosan/monochloroacetic acid molar ratios (1:4.3 or 1:8.6). The carboxymethylation of chitosan was confirmed by ¹H NMR and 13C NMR spectroscopy. The carboxymethylchitosans had average degrees of substitution ranging from 0.52 to 1.44 as determined by potentiometric and conductimetric analysis. The occurrence of N,O-carboxymethylation was also observed in all cases.

Films of chitosan and N,N,N-trimethylchitosan were cast from aqueous solutions. Chitosan was dissolved in 1% acetic acid while deionized water was the solvent for N,N,N-trimethylchitosan chloride. The resulting films presented different mechanical behaviors as evaluated by DMTA. The film of chitosan exhibited an elastic-type behavior while that of N,N,N-trimethylchitosan was typically viscous. No glass transition temperatures were observed; however, a discrete thermal transition was detected at 25 °C in the case of the N,N,N-trimethylchitosan.

The polyelectrolyte complex (PEC) resulting from the reaction of sodium carboxymethylcellulose (CMC) and N,N,N-trimethylchitosan hydrochloride (TMQ) was prepared and then characterized by infrared spectroscopy and energy dispersive X rays analysis. The interactions involving the PEC and Cu2+ ions, humic acid and atrazine in aqueous medium were studied. From the adsorption isotherms the maximum amount adsorbed (Xmax) was determined as 61 mg Cu2+/g PEC, 171 mg humic acid/g PEC and 5 mg atrazine/g PEC. The results show that the CMC/TMQ complex has a high affinity for the studied species, indicating its potential application to remove them from aqueous media.

The shells of Macrobrachium rosenbergii were submitted to deproteinization (Dp) and demineralization (Dm) aiming the extraction of α-chitin. The different parts of the shells were processed independently by carrying out sequence 1 (Dp/Dm) and sequence 2 (Dm/Dp). Both sequences allowed the extraction of chitins with low contents of calcium and magnesium, regardless of the part being processed. The sequence 1 lead to higher extraction yields while sequence 2 resulted in lower contents of inorganic compounds. Extensively deacetylated chitosans (GA

The fact that alpha- and beta-chitin adopt different arrays in the solid state is explored to emphasize their different properties and distinct spectral characteristics and X ray diffraction patterns. The methods for their extraction from the biomass in view of the preservation of their native structures and aiming to fulfill the claims of purity and uniformity for potential applications are discussed. The different arrays adopted by alpha- and beta-chitin also result in distinct reactivities toward the deacetylation reaction. Thus, the deacetylation of beta-chitin is more efficient owing to the better accessibility to amide groups due to the lower crystallinity of this polymorph.

A quitosana é um polissacarídeo linear obtido da desacetilação da quitina. As propriedades físico-químicas da quitosana são função do grau médio de acetilacão e da massa molar média (). Várias aplicações da quitosana foram propostas na literatura, principalmente no tratamento de águas, produção de cosméticos, drogas e medicamentos, aditivos alimentícios, membranas semipermeáveis e no desenvolvimento de biomateriais. Neste trabalho, três diferentes tipos de quitosanas comerciais foram caracterizados por ressonância magnética nuclear de hidrogênio (RMN ¹H), espectroscopia de absorção na região do infravermelho (IV), titulação condutimétrica e análise térmica (TG e DSC) com o objetivo de comparar as características de quitosanas provenientes de diferentes fornecedores. A massa molar média das amostras foi determinada a partir de medidas de viscosidade intrínseca. Os resultados obtidos por estas técnicas mostraram diferenças quanto ao grau médio de acetilação (ou desacetilação), em função da procedência do material. Os resultados obtidos da análise térmica permitiram acompanhar os processos de desidratação, decomposição e a temperatura de transição vítrea (Tg).

Quitosanas comercial e purificadas nas formas neutra, acetato e cloridrato foram caracterizadas e comparadas quanto a solubilidade, hidrofilicidade, morfologia de suas superfícies e cristalinidade. As amostras bruta e purificada na forma neutra apresentam características e propriedades semelhantes, mas as formas salinas, principalmente cloridratos de quitosana, são diferentes. As morfologias das superfícies da amostra comercial e das formas purificadas são semelhantes, mas cloridrato de quitosana obtido por liofilização apresenta poros que não são observados nas outras amostras. Quitosanas comercial e purificada na forma neutra não são solúveis em água, mas acetato de quitosana é parcialmente solúvel. Essas três formas de quitosana apresentam hidrofilicidades e cristalinidades semelhantes, mas nos casos dos cloridratos a presença de cargas e de contra-íons provenientes de um ácido forte aumenta a hidrofilicidade, confere hidrossolubilidade e altera significativamente as interações inter e intracadeias, modificando o empacotamento no estado sólido e resultando em importante decréscimo de cristalinidade. No caso de acetato de quitosana é observado que os cristalitos são menores, o que pode ser atribuído à protonação parcial dos grupos amino e à presença de ânions acetato.

Os processos soda/antraquinona e etanol/água foram aplicados à produção de polpas de fibras e de medulas de bagaço de cana-de-açúcar. Tais polpas foram carboximetiladas em suspensão de isopropanol/água (8/1 m/m) por 4 horas a 80(0)C, empregando a relação molar 8,5/5,4/1 para ácido monocloroacético/hidróxido de sódio/celulose. Os graus médios de susbtituição dos produtos carboximetilados foram determinados por espectroscopia ¹H R.M.N. e variaram entre 0,44 e 1,27 em função da polpa empregada na derivatização. Os derivados mais substituídos foram os melhores absorventes, sugerindo que a capacidade de retenção de água desses produtos está diretamente associada a seus graus de substituição.Two pulping methods were used on fibers and pith of sugar cane bagasse: soda/anthraquinone and ethanol/water. These pulps were submitted to carboxymethylation in a slurry of isopropanol/water (8/1 m/m) at 80ºC for 4 hours using a molar relation 8,8/5,4/1 of monochloroacetic acid/sodium hydroxyde/cellulose. The average degrees of substitution of the carboxymethylated products, determined by ¹H N.M.R. spectroscopy, were between 0.44 and 1.27, depending on the pulp employed for derivatization. The more substituted pulps were the more absorbent products, suggesting that the water retention capacity of these products is closely associated to their degrees of substitution.

Amostras de carboximetilcelulose foram preparadas por reação heterogênea de polpa soda/antraquinona obtida de fibras pré-hidrolisadas de bagaço de cana-de-açúcar. As amostras com os menores graus de substituição ( < 1,0) e as mais substituídas (> 1,0) apresentaram comportamentos diferentes quanto a: i) variação de constante aparente de acidez (pk ap) com o grau de dissociação; ii) concordância entre os valores de determinados por titulações e por espectroscopia ¹H rmn e iii) concordância entre os valores experimentais de coeficientes de transporte e os previstos pelo modelo de Manning. Todas as amostras apresentaram um padrão de substituição em blocos que, nas amostras menos substituídas são curtos e espaçados, favorecendo interações associativas que levam à agregação. Efeitos de volume excluído eletrostático, mais importantes nas amostras mais substituídas, inibem a agregação e explicam o comportamento observado nesses casos.Samples of carboxymethylcellulose were prepared by the heterogeneous reaction of the soda/anthraquinone pulp obtained from sugar cane bagasse. The less substituted samples (DS 1,0) showed different behaviors concerning to: i) the dependence of pk ap on the degree of neutralization; ii) the agreement between DS values determined by titrations and by ¹H nmr spectroscopy and iii) the agreement between the experimental values of transport coefficients (f) and the ones calculated by applying the Manning theoretical approach. All samples showed a block distribution of substituents which, in the case of the less substituted samples, are short and well separated, favoring the occurrence of associative interactions and of aggregation. Electrostatic excluded volume effects, which are more important for the more substituted samples, inhibit the aggregation and may explain the behavior of these samples.

RESUMO: Procedimentos adequados para as purificações de quitosana comercial como cloridrato e na forma neutralizada são descritos. As amostras obtidas apresentam elevado grau de pureza e baixo teor de cinzas conforme verificado através de termogravimetria. As determinações de graus de acetilação por espectroscopia de ressonância magnética nuclear ( ou = 23,6%) e por titulações ( ou = 23,0%) apresentam muito boa concordância. O cloridrato de quitosana é solúvel em água, o que permite determinações de viscosidade intrínseca em solventes aquosos na ausência de excesso de ácido e facilita a comparação de quitosana com outros polieletrólitos quanto a estimativas de rigidez/flexibilidade.ABSTRACT: The procedures for the purification of a commercial chitosan as a hydrochloride and in the neutralized form are described. By applying these procedures, pure chitosans of low ash contents are obtained as determined by thermogravimetry. The agreement between the values of degrees of acetylation determined by conductimetric titrations ( or = 23,0%) and by ¹H nmr spectroscopy ( or = 23,6%) is very good. Chitosan hydrochloride being soluble in pure water allows the determination of intrinsic viscosity in dilute acid-free aqueous solutions and makes easier the comparison of chitosan and other polyelectrolytes with respect to their chain rigidity/flexibility.

RESUMO: Polpas etanol/água de medula de bagaço de cana de açúcar foram empregadas para a obtenção de carbóxi-metil-celulose insolúvel, aplicável como material absorvente. Tipicamente, a reação de carbóxi-metilação da polpa branqueada foi realizada em suspensão de isopropanol/água (1:8 / m:m) a 80 ºC por 4 horas, empregando-se relação molar 1 / 5,4 / 8,8 de celulose / NaOH / ClAcOH. O material com melhores características corresponde a um produto muito pouco solúvel (S W < 2%), com propriedades absorventes superiores às da polpa de partida.ABSTRACT: Ethanol/water pulp of pith from sugar cane bagasse was used for the obtention of insoluble carboxymethylcellulose applicable as absorbent material. Typically the carboxymethylation reaction of the bleached pulp was carried out at 80 °C for 4 hours in isopropanol/water suspension 1:8 (w/w) employing a 1.0 / 5.4 / 8.8 cellulose / NaOH / ClAcOH molar ratio. The material with the best absorbent characteristics corresponds to a very insoluble product (S W < 2%) possessing better absorbent properties than the pulp of pith used for its obtention.