227 research outputs found
Bureaucracy and Contracts of Adhesion
Under the political theory of the liberal state, there is no adequate traditional justification for contracts of adhesion. Professor Macneil seeks to locate their legitimacy in the nature of modern bureaucracy. He demonstrates how this mode of legitimation sets limits for government intervention. In his conclusion, Professor Macneil emphasizes the significance of his analysis for a fuller understanding of the validity and the complex operation of contracts of adhesion
Antimicrobial graft copolymer gels
In view of the growing worldwide rise in microbial
resistance, there is considerable interest in designing new antimicrobial
copolymers. The aim of the current study was to investigate the
relationship between antimicrobial activity and copolymer composition/
architecture to gain a better understanding of their mechanism of action.
Specifically, the antibacterial activity of several copolymers based on 2-
(methacryloyloxy)ethyl phosphorylcholine [MPC] and 2-hydroxypropyl
methacrylate (HPMA) toward Staphylococcus aureus was examined. Both
block and graft copolymers were synthesized using either atom transfer
radical polymerization or reversible addition−fragmentation chain
transfer polymerization and characterized via 1H NMR, gel permeation
chromatography, rheology, and surface tensiometry. Antimicrobial
activity was assessed using a range of well-known assays, including
direct contact, live/dead staining, and the release of lactate dehydrogenase
(LDH), while transmission electron microscopy was used to study the morphology of the bacteria before and after the
addition of various copolymers. As expected, PMPC homopolymer was biocompatible but possessed no discernible antimicrobial
activity. PMPC-based graft copolymers comprising PHPMA side chains (i.e. PMPC-g-PHPMA) significantly reduced both
bacterial growth and viability. In contrast, a PMPC−PHPMA diblock copolymer comprising a PMPC stabilizer block and a
hydrophobic core-forming PHPMA block did not exhibit any antimicrobial activity, although it did form a biocompatible worm
gel. Surface tensiometry studies and LDH release assays suggest that the PMPC-g-PHPMA graft copolymer exhibits surfactantlike
activity. Thus, the observed antimicrobial activity is likely to be the result of the weakly hydrophobic PHPMA chains
penetrating (and hence rupturing) the bacterial membrane
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