The mechanism underlying the bioinertness of the self-assembled monolayers of oligo(ethylene glycol)-terminated alkanethiol (OEG-SAM) was investigated with protein adsorption experiments, platelet adhesion tests, and surface force measurements with an atomic force microscope (AFM). In this work, we performed systematic analysis with SAMs having various terminal groups (-OEG, -OH, -COOH, -NH(2), and -CH(3)). The results of the protein adsorption experiment by the quartz crystal microbalance (QCM) method suggested that having one EG unit and the neutrality of total charges of the terminal groups are essential for protein-resistance. In particular, QCM with energy dissipation analyses indicated that proteins absorb onto the OEG-SAM via a very weak interaction compared with other SAMs. Contrary to the protein resistance, at least three EG units as well as the charge neutrality of the SAM are found to be required for anti-platelet adhesion. When the identical SAMs were formed on both AFM probe and substrate, our force measurements revealed that only the OEG-SAMs possessing more than two EG units showed strong repulsion in the range of 4 to 6 nm. In addition, we found that the SAMs with other terminal groups did not exhibit such repulsion. The repulsion between OEG-SAMs was always observed independent of solution conditions [NaCl concentration (between 0 and 1 M) and pH (between 3 and 11)] and was not observed in solution mixed with ethanol, which disrupts the three-dimensional network of the water molecules. We therefore concluded that the repulsion originated from structured interfacial water molecules. Considering the correlation between the above results, we propose that the layer of the structured interfacial water with a thickness of 2 to 3 nm (half of the range of the repulsion observed in the surface force measurements) plays an important role in deterring proteins and platelets from adsorption or adhesion.

Rolling bearing is the most part used in rotating machinery of industrial plant. The condition diagnosis technology of rolling bearing is very important and indispensable for the plant safety and operation stability. The purpose of this study is to improve the accuracy of the life prediction for a rolling bearing. The paper proposes a searching method for the optimum mathematic function for the high accurate prediction by using the genetic algorithms (GA).

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When thymidine was treated with hypobromous acid (HOBr) in 100 mM phosphate buffer at pH 7.2, two major product peaks appeared in the HPLC chromatogram. The products in each peak were identified by NMR and MS as two isomers of 5-hydroxy-5,6-dihydrothymidine-6-phosphate (a novel compound) and two isomers of 5,6-dihydroxy-5,6-dihydrothymidine (thymidine glycol) with comparable yields. 5-Hydroxy-5,6-dihydrothymidine-6-phosphate was relatively stable, and decomposed with a half-life of 32 h at pH 7.2 and 37°C generating thymidine glycol. The results suggest that 5-hydroxy-5,6-dihydrothymidine-6-phosphate in addition to thymidine glycol may have importance for mutagenesis by the reaction of HOBr with thymine residues in nucleotides and DNA. For thymidine (Thd), bromine water generated 5,6-dihydroxy-5,6-dihydrothymidine (thymidine glycol, TG). 16,17) TG is a common oxidative product of Thd with ionizing radiation and various oxidants including permanganate and HOCl. [18][19][20] TG exists as four stereoisomers, cis-5R,6S, cis-5S,6R, trans-5R,6R, and trans-5S,6S. Two diastereomeric pairs (cis-5R,6S/trans-5R,6R and cis-5S,6R/trans-5S,6S) are in an equilibrium in water. In both the epimerization equilibriums, the cis forms are predominant (87 : 13 for cis-5R,6S : trans-5R,6R, 80 : 20 for cis-5S,6R : trans-5S,6S) in a neutral solution (pH 7.4). 21) In the present study, we investigated the reaction of Thd with reagent HOBr in phosphate buffer and report the formation of a novel product in addition to TG. Results and DiscussionA solution of 1 mM Thd was incubated with 1 mM HOBr in 100 mM potassium phosphate buffer (pH 7.2) at 37°C for 30 min. The reaction was monitored by reversed phase high performance liquid chromatography (RP-HPLC) with detection at 230 nm. Thd was consumed greatly and several product peaks were observed in the RP-HPLC chromatogram (Fig. 1). A peak (termed Peak 1) at an HPLC retention time of 3.7 min showed a UV spectrum with λ max =215 nm in the online detected UV spectrum. Peak 1 was isolated and subjected to electrospray ionization time of flight mass spectrometry (ESI-TOF/ MS) and NMR measurements. Peak 1 showed an ESI-TOF/ MS spectrum with m/z=257 and 355 in the negative mode ( Fig. 2A). High-resolution (HR)-ESI-TOF/MS of the molecular ion showed m/z=355.055257, which agreed with the theoretical molecular mass for C 10 H 15 N 2 O 10 P composition within 2 ppm. The NMR measurements showed that Peak 1 included two compounds with an abundance ratio of 2.6 : 1 (compound 1-1 : compound 1-2).

We have designed a novel lipid analog (lipopeptide) that mimics the structural features of modiˆed phospholipids. This lipopeptide is easily synthesized using a peptide synthesizer and has been shown to be useful for the modiˆcation of liposomes, which are used as an active targeted drug delivery system (DDS). Vasoactive intestinal peptide (VIP) has high homology with pituitary adenylate cyclase activating peptide (PACAP). There are three major PACAP receptors: PAC1R, VPAC1R, and VPAC2R. PAC1R has a‹nity only for PACAP, whereas VPAC1R and VPAC2R have the same a‹nity for both VIP and PACAP. In the present study, we synthesized several lipopeptides conjugated with VIP through diŠerent linkers and found that liposomes modiˆed with these lipopeptides (VIP-Lips) selectively recognized the PACAP/VIP receptors. The anti-cancer activity of these VIP-Lips was evaluated by encapsulation of an antitumor drug, doxorubicin (DOX), into the modiˆed liposomes (VIP-Lips-DOX) against the human osteosarcoma cell line, Saos-2, which highly expresses the VIP receptor. cAMP production was then measured to determine how well the VIPLips were able to recognize VPAC2R. The results clearly indicate that the proposed lipopeptide methodology holds promise as a DDS for cancer therapy.