Direct enzymatic esterification of cotton and Avicel with wild-type and engineered cutinases

In this work, the surface of cellulose, either Avicel or cotton fabric, was modified using cutinases without any previous treatment to swell or to solubilise the polymer. Aiming further improvement of cutinase ester synthase activity on cellulose, an engineered cutinase was investigated. Wild-type cutinase from Fusarium solani and its fusion with the carbohydrate-binding module N1 from Cellulomonas fimi were able to esterify the hydroxyl groups of cellulose with distinct efficiencies depending on the acid substrate/solvent system used, as shown by titration and by ATR-FTIR. The carbonyl stretching peak area increased significantly after enzymatic treatment during 72 h at 30 °C. Cutinase treatment resulted in relative increases of 31 and 9 % when octanoic acid and vegetable oil were used as substrates, respectively. Cutinase-N1 treatment resulted in relative increases of 11 and 29 % in the peak area when octanoic acid and vegetable oil were used as substrates, respectively. The production and application of cutinase fused with the domain N1 as a cellulose ester synthase, here reported for the first time, is therefore an interesting strategy to pursuit.This work was co-funded by the European Social Fund through the management authority POPH and FCT, Postdoctoral fellowship reference: SFRH/BPD/47555/2008. The authors also want to thank Doctor Raul Machado for his valuable help on FTIR spectral data treatment

Development and application of a capillary electrophoresis method for the determination of ellagic acid in E. globulus wood and in filtrates from E. globulus kraft pulp

A capillary zone electrophoresis (CZE) method for simple and rapid determination of ellagic acid (EA) in Eucalyptus globulus wood and in the filtrate from unbleached kraft pulp has been developed. This is the first application of CZE for the detection of EA in industrial streams from cellulosic pulp production. The EA determinations in wood extractives and in pulp filtrates were succeeded only after sample acidification. This new CZE analytical procedure allowed reliable determinations of EA in E. globulus wood (1.1 ± 0.6 g kg-1 of dry wood) and in the filtrates from unbleached kraft pulp (98 ± 0.7 mg L-1). Gas chromatography-mass spectrometry was used as a reference method for the quantification of EA in industrial samples

Sustainable nanocomposite films based on bacterial cellulose and pullulan

Bionanocomposites with improved properties based on two microbial polysaccharides, pullulan and bacterial cellulose, were prepared and characterized. The novel materials were obtained through a simple green approach by casting water-based suspensions of pullulan and bacterial cellulose and characterized by TGA, RDX, tensile assays, SEM and AFM. The effect of the addition of glycerol, as a plasticizer, on the properties of the materials was also evaluated. All bionanocomposites showed considerable improvement in thermal stability and mechanical properties, compared to the unfilled pullulan films, evidenced by the significant increase in the degradation temperature (up to 40 A degrees C) and on both Young's modulus and tensile strength (increments of up to 100 and 50%, for films without glycerol and up to 8,000 and 7,000% for those plasticized with glycerol). Moreover, these bionanocomposite films are highly translucent and could be labelled as sustainable materials since they were prepared entirely from renewable resources and could find applications in areas as organic electronics, dry food packaging and in the biomedical field

The effect of side-chain length of cellulose fatty acid esters on their thermal, barrier and mechanical properties

Currently, long-chain cellulose esters are not produced commercially because of high price, and since their preparation typically requires a large quantity of chemicals. To reduce the chemical consumption, cellulose reactivity needs to be increased without losing its quality. One way to increase the reactivity of cellulose is to decrease its molar mass in a controlled manner. In this study, we have synthesized cellulose esters with different side-chain length (C6-C18) in a homogeneous system using ozone molar mass-controlled cellulose. The target was to keep the degree of substitution as low as possible while still ensuring the suitability of cellulose esters for solvent casting. Thermal, barrier and mechanical properties were studied depending on cellulose fatty acid ester side-chain length. All our molar mass-controlled cellulose esters form optically transparent, flexible and heat-sealable films with good water barrier properties and are processable without the addition of an external plasticizer. Furthermore, the films have mechanical properties comparable to some generally used plastics. These good properties suggest that our molar mass-controlled cellulose esters could be potential candidates for various applications such as films and composites