Although modern dental repair materials show excellent mechanical and adhesion properties, they still face two major problems: First, any microbes that remain alive below the composite fillings actively decompose dentin and thus, subsequently cause secondary caries. Second, even if those microbes are killed, the extracellular proteases such as MMP, remain active and can still degrade collagenousdental tissue. In order to address both problems, a poly(2-methyloxazoline) with a biocidal quaternary ammonium and a polymerizable methacrylate terminal was explored as additive for a commercial dental adhesive. It could be demonstrated that the adhesive rendered the adhesive contact-active antimicrobial against S. mutans at a concentration of only 2.5 wt% and even constant washing with water for 101 days did not diminish this effect. Increasing the amount of the additive to 5 wt% allowed killing S. mutans cells in the tubuli of bovinedentin upon application of the adhesive. Further, the additive fully inhibited bacterial collagenase at a concentration of 0.5 wt% and reduced human recombinant collagenase MMP-9 to 13% of its original activity at that concentration. Human MMPs naturally bound to dentin were inhibited by more than 96% in a medium containing 5 wt% of the additive. Moreover, no adverse effect on the enamel/dentine shear bond strength was detected in combination with a dental composite.
Novel
amphiphilic polymer conetworks (APCNs) were prepared via
end group cross-linking. To this end, poly(2-methyloxazoline) (PMOx),
poly(2-butyloxazoline) (PBuOx), and the triblock copolymers PMOx-b-PBuOx-b-PMOx were synthesized by cationic
ring-opening polymerization in varying block lengths and telechelically
modified with
N,N
-bis(2-aminoethyl)ethylendiamine
(TREN). First the cross-linking with 1,4-dibromo-2-butene (DBB) was
established for the homopolymers. The swelling of those matches the
theoretical value for full cross-linking, indicating that in this
way “near perfect” networks could be obtained. Mixtures
of the homopolymers and the triblock copolymers were cross-linked
with DBB to give APCNs with similar polymer segments but different
network topology. AFM showed that all formed APCNs are nanophase separated
with slight structural differences in the nanostructures when comparing
conetworks with similar composition but different cross-linking strategies.
The more drastic difference between APCNs of different topologies
was found in their swelling characteristics, which clearly proves
the influence of conetwork structure on their properties.
Conjugates of enzymes and poly(2-methyloxazoline) were used as organosoluble amphiphilic polymer nanocontainers for dissolving osmate, thereby converting the enzymes into organosoluble artificial metalloenzymes. These were shown to catalyze the dihydroxylation of different alkenes with high enantioselectivity. The highest selectivities, found for osmate complexed with laccase polymer-enzyme conjugates (PECs), even exceed those of classical Sharpless catalysts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.