Cellulose: from biocompatible to bioactive material

International audienceSince the papyri, cellulose has played a significant role in human culture, especially as paper. Nowadays, this ancient product has found new scientific applications in the expanding sector of paper-based technology. Among paper-based devices, paper-based biosensors raise a special interest. The high selectivity of biomolecules for target analytes makes these sensors efficient. Moreover, simple paper-based detection devices do not require hardware or specific technical skill. They are inexpensive, rapid, user-friendly and therefore highly promising for providing resource-limited settings with point-of-care diagnostics. The immobilization of biomolecules onto cellulose is a key step in the development of these sensing devices. Following an overview of cellulose structural features and physicochemical properties, this article reviews current techniques for the immobilization of biomolecules on paper membranes. These procedures are categorized into physical, biological and chemical approaches. There is no universal method for biomolecule immobilization. Thus, for a given paper-based biochip, each strategy can be considered

"Salting-out" chromatography: Empirical equations relating RF values to atomic refraction constants

Peptides, [alpha]-amino acids and miscellaneous organic compounds were chromatographed on filter paper using saturated ammonium sulfate solution as the developing solvent. Equations relating RF values to molecular refraction constants were derived empirically. Applications of such equations in predicting RF values and obtaining information concerning molecular structure are discussed briefly.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32497/1/0000584.pd

Free and nonprotein amino acids of Tetrahymena pyriformis

Paper chromatography was used to determine 20 amino acids and related compounds present in both the free and the nonprotein forms in Tetrahymena pyriformis. The most abundant free amino acids in the cells were found to be glutamic acid, alanine, leucine-isoleucine, glycine, arginine, and lysine. Free methionine, cystine, and tryptophan were present in the smallest quantities. A relatively large proportion of aspartic acid, glycine, and glutamic acid was found in the conjugated form, while nearly all nonprotein arginine and lysine occurred in the free form. In line with values observed in other invertebrates and microorganisms, the [alpha]-amino nitrogen present in the free and the nonprotein forms constituted as high as a fifth and a fourth, respectively, of the total nitrogen of the protozoan cells.A fairly constant ratio of the amino acid content of the whole cell to that of the cellular protein was obtained, which indicated that the amino acid composition of the whole cell reflects that of the cellular protein.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32514/1/0000605.pd