Oligonucleotide 9mers containing 2'-O-(1-pyrenylmethyl)uridine [U(pyr)] at the center position were synthesized by using a protected U(pyr) phosphoramidite. The UV melting behaviors indicate that the pyrene-modified oligonucleotides can bind to both their complementary DNA and RNA in aqueous solution. When compared with the unmodified oligonucleotides, the pyrene-modified oligonucleotides showed higher affinity for DNA while exhibiting lower affinity for RNA. The pyrene-modified oligonucleotides in diluted solution exhibited fluorescence typical of pyrene monomer emission [lambdamax 378 (band I) and 391 nm (band III)]. When these oligomers bound to DNA, the fluorescence intensity ratio of band III/band I was increased. With this fluorescence change, a new broad emission (lambdamax 450 nm) due to exciplex between the pyrene and an adjacent nucleobase appeared. In contrast, addition of RNA to the pyrene oligonucleotides resulted in enhancement of the pyrene monomer emission with decrease in the fluorescence band ratio. The extent of the emission enhancement was found to be highly dependent on the nucleobase adjacent to the U(pyr) in the pyrene oligomers. The pyrene oligonucleotide containing dC at the 3'-site of the modification showed remarkable increase (approximately 250 times) in fluorescence (375 nm) upon binding to complementary RNA. The present findings would open the way to the design of a highly sensitive fluorescent probe of RNA.

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Alkenyl succinic anhydride (ASA) is well known as one of the synthetic sizing agents widely used in neutral papermaking and its role at higher pH range sizing has become important because of environmental issues, the lifting ratio of recycling pulp, anion trash increase in papermaking system and so on. Although many literatures on ASA have been published, we studied the mechanism of ASA sizing by using both ASA and ASAcid (hydrolyzed ASA) in order to obtain further comprehension. In this experiment. sizing treatment was carried out under ideal conditions where the filter paper was immersed in ASA emulsion or in the toluene solution of ASA, so as to retain the same quantity of sizing material in filter paper. The same procedure was adopted in the case of ASAcid. Contrary to our expectations, the most notable fact from the results obtained is that the sizing effect of the filter paper treated with ASA emulsion is superior to that of ASA toluene solution. These results suggest that the most essential factor to develop sizing is morphology of sizing material distribution on fibers. We speculate that the entirely uniform distribution of sizing material, like a uniform thin film, is not necessary for sizing development but the scattered distribution, like dots, is required.