Isoeugenol-functionalized nanogels inhibit peri-implantitis associated bacteria in vitro.

OBJECTIVES: Obligate and facultative anaerobic bacteria adhering to dental implants are a major cause for peri-implant inflammation, which, if left untreated, can lead to implant loss. Previously, our group developed a new route for the synthesis of isoeugenol-functionalized aqueous nanogels for implant coatings. METHODS: Here, the antimicrobial activity of several new nanogels differing in spacer length (n = 6, 9, 44), radius (60-200 nm), and amount of isoeugenol functional substance (1-20 mol%) was tested against the following peri-implantitis-associated species: Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Aggregatibacter actinomycetemcomitans, Escherichia coli, Actinomyces viscosus, Enterococcus faecalis, Staphylococcus aureus, Streptococcus oralis, S. parasanguinis, and the yeast Candida albicans. The minimal bactericidal concentration (MBC) and fungicidal concentration (MFC) were determined for each combination. In addition, transmission electron microscopy (TEM) and fluorescence microscopy after live-dead-staining (LD-S) were performed to visualize nanogel-microbe interactions. RESULTS: Two nanogels, NG9-3 and NG9-4 (colloids of 80-150 nm, with a spacer length of n = 9 and feeding between 5 and 10 mol% isoeugenol), had an inhibitory effect on all Gram-positive species and on P. gingivalis and P. intermedia with MBC ≥31.25 µg/ml. TEM and LD-S images showed that cellular adhesion and uptake of nanogels resulted in swelling, shedding, or even complete detachment of the cell wall and then to bursting (see graphical abstract). CONCLUSIONS: Functional nanogels can be used as building blocks in the design of bioactive coatings on implants to prevent infection and accelerate tissue regeneration, but the concentrations required are higher than for antibiotics.

Biofunctionalized zinc peroxide nanoparticles inhibit peri-implantitis associated anaerobes and Aggregatibacter actinomycetemcomitans pH-dependent.

For dental implants the accumulation of anaerobic bacteria is a main reason for peri-implant inflammation, which untreated can lead to implant loss. Oxygen releasing substances may act as antibacterial agents. In this study glucose-1-phosphate (Glc-1P) biofunctionalized zinc peroxide (ZnO2) nanoparticles of four different synthesis ratio (1-10:1) and sizes (4-5 nm) were tested against the anaerobes Fusobacterium nucleatum, Porphyromonas gingivalis, and Prevotella intermedia, as well as against Aggregatibacter actinomycetemcomitans, Enterococcus faecalis, Staphylococcus aureus, Lactobacillus paracasei, and the yeast Candida albicans. Nanoparticles stabilized with o-phosphorylethanolamine, bis[2-(methacryloyloxy)ethyl] phosphate, or dioctyl sulfosuccinate instead of glucose were used as controls. For every combination of test strain and nanoparticle both, the minimal inhibitory (MIC) and minimal microbicidal concentration (MBC or MFC) were determined under different pH conditions in microtiter plates. Furthermore, transmission electron (TEM) and fluorescence microscopy after live-dead-staining was performed on selected combinations of pathogen and nanoparticle in order to visualize the interactions. The ZnO2/Glc-1P nanoparticles had an inhibitory effect on gram-negative anaerobes and on A. actinomycetemcomitans with a pH-dependent MIC ≥25 µg/ml and MBC ≥50 µg/ml, while the gram-positive species tested and C. albicans were not inhibited. In TEM images, attachment of nanoparticle-chains to the bacterial outer membrane and subsequent penetration was found together with an intracellular oxygen release. For nanoparticles with other stabilizers than glucose an invasion was only seen in elongated, dividing cells, possibly because of the more porous cell wall in the parting layer. Decorating ZnO2 by glucose-1-phosphate is a Trojan horse approach to permit their uptake in gram-negative oxygen-sensitive bacterial cells.

Biadhesive Peptides for Assembling Stainless Steel and Compound Loaded Micro-Containers.

Biadhesive peptides (peptesives) are an attractive tool for assembling two chemically different materials-for example, stainless steel and polycaprolactone (PCL). Stainless steel is used in medical stents and PCL is used as a biodegradable polymer for fabrication of tissue growth scaffolds and drug delivering micro-containers. Biadhesive peptides are composed of two domains (e.g., dermaseptin S1 and LCI) with different material-binding properties that are separated through a stiff peptide-spacer. The peptesive dermaseptin S1-domain Z-LCI immobilizes antibiotic-loaded PCL micro-containers on stainless steel surfaces. Immobilization is visualized by microscopy and field emission scanning electron microscopy analysis and released antibiotic from the micro-containers is confirmed through growth inhibition of Escherichia coli cells.

Chemo-enzymatic conversion of glucose into 5-hydroxymethylfurfural in seawater.

Do you sea water? Water consumption will be a challenge in biorefineries, and the use of non-drinkable sources of water will be preferred. Herein, glucose is converted into 5-hydroxymethylfurfural (HMF) in a chemo-enzymatic one-pot, two-step procedure, involving immobilized glucose isomerase to produce fructose and oxalic acid to dehydrate it to HMF.