Inhibition of type 1 fimbriae-mediated Escherichia coli adhesion and biofilm formation by trimeric cluster thiomannosides conjugated to diamond nanoparticles

Abstract

Inhibition of type 1 fi mbriae-mediated Escherichia coli adhesion and biofi lm formation by trimeric cluster thiomannosides conjugated to diamond nanoparticles Trimeric thiosugar clusters, conveniently obtained through a thiol-ene "click" strategy, have been effi ciently conjugated to alkynyl-functionalized nanodiamonds (NDs) using a Cu(I)-catalysed "click" reaction. These tri-thiomannoside clusterconjugated NDs (ND-Man 3 ) are shown to be potent inhibitors of type 1 fi mbriae-mediated E. coli adhesion to yeast and T24 bladder cells and moreover to inhibit E. coli-mediated biofi lm formation. This latter feature has only rarely been reported in the past for analogues featuring such simple multivalent glycosidic motifs and would constitute a useful additional characteristic of any anti-adhesive drug lead. anti-adhesive nanoparticles displaying activity against biofilms. In this work, trimeric thiomannoside clusters conjugated to nanodiamond particles (ND) were targeted for investigation. NDs have attracted attention as a biocompatible nanomaterial and we were curious to see whether the high mannose glycotope density obtained upon grouping monosaccharide units in triads might lead to the corresponding NDconjugates behaving as effective inhibitors of E. coli type 1 fimbriae-mediated adhesion as well as of biofilm formation. The required trimeric thiosugar clusters were obtained through a convenient thiol-ene "click" strategy and were subsequently conjugated to alkynyl-functionalized NDs using a Cu(I)-catalysed "click" reaction. We demonstrated that the tri-thiomannoside cluster-conjugated NDs (ND-Man 3 ) show potent inhibition of type 1 fimbriae-mediated E. coli adhesion to yeast and T24 bladder cells as well as of biofilm formation. The biofilm disrupting effects demonstrated here have only rarely been reported in the past for analogues featuring such simple glycosidic motifs. Moreover, the finding that the tri-thiomannoside cluster (Man 3 N 3 ) is itself a relatively efficient inhibitor, even when not conjugated to any ND edifice, suggests that alternative mono-or multivalent sugar-derived analogues might also be usefully explored for E. coli-mediated biofilm disrupting properties.

Unprecedented inhibition of glycosidase-catalyzed substrate hydrolysis by nanodiamond-grafted O-glycosides

“…[18][19][20][21][22][23][24][25] Advantages over related conjugates based on fullerenes and carbon nanotubes include their complete inertness, optical transparency, lack of signicant cytotoxicity for a variety of cell types, [26][27][28] as well as their ease of functionalization through a variety of methods depending on ultimate application. Diamond nanoparticles (also termed nanodiamonds) are amongst the most promising new carbon-based materials currently being evaluated for biomedical applications.…”

“…Diamond nanoparticles (also termed nanodiamonds) are amongst the most promising new carbon-based materials currently being evaluated for biomedical applications. 18,19,25,29,30 In an extension of this work we were curious to establish whether these O-glycoside-conjugated ND were indeed stable to the hydrolytic action of glycosidases and report herein the unprecedented nding that monosaccharide substrates of selected glycosyl hydrolases are not only stable to hydrolysis but moreover behave as competitive, reversible inhibitors of their complementary (matching) glycosidase, simply upon being conjugated in a multivalent fashion to an ND edice. Mannosefunctionalized ND, for example, has been shown to inhibit yeast-agglutination as well as human bladder-cell adherence by E. coli and most notably to be able to disrupt biolm formation.…”

Glycoconjugates and Glycomimetics as Microbial Anti-Adhesives

“…against gut-colonizing AIEC), or when FimH adhesion is exploited to achieve bacterial aggregation and biofilm disruption. They vary from medium-sized scaffolds [19][20][21][22][23], to dendrimers [3,24], polymers [25] and nanoparticles [26][27][28][29]. Despite the spacing between fimbriae can vary between strains and depends on growth conditions [30], only the largest of these materials are likely to engage more than one protein at the time, because the FimH binding site can interact with only one mannose residue at the time and each of the fimbriae carries only a single copy of FimH.…”

“…In most other systems, the multivalency effects observed are not likely to depend on chelation, but rather on increased local concentration of the ligand (statistical rebinding). Affinity improvements have been measured also for materials of moderate valency (up to 12 mannose units) in inhibition experiments with isolated FimH E. coli aggregation in water solution, using large polyvmannosylated constructs is under active examination for detection and removal from polluted water [27] and as a model system for anti-infective studies in vivo [21] or ex vivo [25,29]. Glyconanodiamonds (GNDs) have been used towards this end.…”

“…The use of GNDs as potent and specific anti-adhesives against E. coli adhesion to human bladder cells and their interference with biofilm formation was recently reported [29].…”