There is a great interest in increasing the levels of production of nanocellulose, either by adjusting production systems or by improving the raw material. Despite all the advantages and applications, nanocellulose still has a high cost compared to common fibers and to reverse this scenario the development of new, cheaper, and more efficient means of production is required. The market trend is to have an increase in the mass production of nanocellulose; there is a great expectation of world trade. In this sense, research in this sector is on the rise, because once the cost is not an obstacle to production, this material will have more and more market. Production of the cellulose fibers is determinant for the production of nanocellulose by a hydrolyzing agent with a reasonable yield. This work presents several aspects of this new material, mainly addressing the enzymatic pathway, presenting the hydrolysis conditions such as pH, biomass concentration, enzymatic loading, temperature, and time. Also, the commonly used characterization methods are presented, as well as aspects of the nanocellulose production market.

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-Biosensors based on nanomaterial composites have been investigated for their potential to function as high sensitivity signal response devices. In the present study, we report the fabrication of silver nanoparticles (AgNPs) on a graphite epoxy composite electrode (GEC) and mixed with the polyaniline (a conductive emeraldine salt form polymer) composite electrode (AgNPs/PANI/GEC), in order to compare the performance of the generated electrochemical response signals. Cyclic voltammetry tests were conducted to compare the quality and intensity of signals from the different prepared electrodes. Tests for the AgNPs/PANI/GEC electrodes were made with and without the enzymes alcohol oxidase and horseradish peroxidase immobilized on the composite surface. The prepared AgNPs/PANI/GEC nanocomposite was evaluated by thermal analysis. Scanning electron microscopy images and EDX were obtained for characterization of the electrode surface morphology. Square wave voltammetry techniques were then employed for ethanol analysis with the AOX/HRP/AgNPs/PANI/GEC biosensor achieving good results in a range of 0.37M to 0.65 M.

RESUMO -O objetivo deste trabalho é determinar o efeito da incorporação de nanoparticulas de prata (AgNPs) estabilizadas em borohidreto de sódio em compósito Grafite/Epóxi (GEC) e sua aplicação em biossensor eletroquímico a base de Horseradish peroxidase (HRP) como dispositivo de medição e monitoramento da concentração de etanol biocombustível em processos fermentativos. A enzima álcool-oxidase oxida álcoois de baixo peso molar utilizando como receptor de elétrons o oxigênio molecular. Para determinar o empenho dos biossensores foram testados em voltametria cíclica a diferentes concentrações de etanol e velocidades de varredura de 10 a 100 mV/s. A incorporação das AgNPs melhorou as propriedades elétricas, ópticas e dielétricas dos compósitos atuando como condutoras entre o grafite, e elevou a condutância elétrica do compósito. A utilização de enzimas nos biossensores tem se tornado uma alternativa interessante por apresentar um menor gasto em pré-tratamentos além do aumento da especificidade.

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