A Novel Surface Modification and Immobilization Method of Anti-CD25 Antibody on Nonwoven Fabric Filter Removing Regulatory T Cells Selectively.

Anti-CD25 antibodies were immobilized on polypropylene (PP) nonwoven fabrics to specifically remove mouse regulatory T cells (Tregs) from mouse spleen cells. PP fibers were coated with peptide nanosheets, which were prepared by self-assembling of a mixture of X-poly(sarcosine)-b-(l-Leu-Aib)6 (X: glycolic acid or a phenylboronic acid) and Y-poly(sarcosine)-b-(d-Leu-Aib)6 (Y: glycolic acid or diazirine derivative). Anti-CD25 antibodies were immobilized by covalent linking between the sugar moiety of the antibody and the phenylboronic acid group on the peptide nanosheet. The removal rate of mouse Tregs from the mouse spleen cells was more than 95% only by passing the filters, while the nonspecific removal rates of other cells were less than 15%. The coating of peptide nanosheets on PP fibers was very effective to provide a suitable environment for the immobilized antibody to interact with the counterpart cells while the coating suppressed nonspecific adsorption of other cells.

Properties and reactivity of the adenosine radical generated by radiation-induced oxidation in aqueous solution.

The formation of oxidation products of DNA bases induced by hole injection into DNA duplexes is closely related to the characteristics of the radical species generated, especially those from purine bases possessing lower oxidation potentials than pyrimidines. To investigate the reactivities of adenosine base radicals generated from the radical cations of adenosine (Ado), we have conducted extensive pulse radiolysis and steady-state X-radiolysis investigations of Ado under the conditions generating oxidizing radical species such as the sulfate radical anion (SO(4)(-*)). Kinetic analysis of the transient absorption spectra demonstrated that the redox-neutral radical of adenosine [Ado(-H)(*)] decays via a homogeneous bimolecular reaction, recombines with an alkyl alcohol radical, or abstracts hydrogen from the phosphate ion, with rate constants of 2k = 4.2 x 10(8) M(-1) s(-1) and k = 6.4-8.5 x 10(8) and 10(3)-10(4) M(-1) s(-1), respectively. High-dose pulsed electron beam irradiation, which generates high concentrations of Ado(-H)(*) during the radiolysis, yielded 8-oxo-7,8-dihydroadenosine (8-oxo-Ado) with a G value of 0.018 x 10(-7) mol J(-1). It is thus proposed that the disproportionation of Ado(-H)(*) might lead to the formation of 8-oxo-Ado as a minor process, which is in addition to the widely accepted mechanism in which the addition of hydroxyl radical to Ado initiates its formation.