ABSTRACT
Nanocarbons come in many forms and among their applications is the engineering of biocompatible and antibacterial materials. Studies have shown that diamond nanoparticles might have the interesting combination of both properties: they are highly biocompatible, while surprisingly reducing bacterial viability or growth at the same time. In this article, we consider for the first time the interaction of milled HPHT nanodiamonds with bacteria. These nanoparticles are capable of hosting nitrogen-vacancy (NV) centers, which provide stable fluorescence with potential use in sensing applications. An initial study was performed to assess the interaction of partially oxidized monocrystalline nanodiamonds with Gram positive S. aureus ATCC 12600 and Gram negative E. coli ATCC 8739. It was shown that for S. aureus ATCC 12600, the presence of these nanodiamonds leads to a sharp reduction of colony forming ability under optimal conditions. A different effect was observed on Gram negative E. coli ATCC 8739, where no significant adverse effects of ND presence was observed. The mode of interaction was further studied by electron microscopy and confocal microscopy. The effects of NDs on S. aureus viability were found to depend on many factors, including the concentration and size of nanoparticles, the suspension medium and incubation time.
Subject(s)
Escherichia coli/drug effects , Nanodiamonds , Staphylococcus aureus/drug effects , Microscopy, Confocal , Microscopy, Electron, Scanning , NitrogenABSTRACT
OBJECTIVE: To determine in preterm infants with a patent ductus arteriosus (PDA) the effect of indomethacin treatment on spontaneous motor activity. STUDY DESIGN: Motor activity was assessed from repeated videotape recordings in 32 preterm infants (=33 weeks gestation). Sixteen infants required indomethacin therapy for treatment of PDA, 16 were control infants, matched for gestational age. Indomethacin (0.2 mg/kg i.v. in 5 min) was given thrice, with an interval of 12 h. One-hour recordings were made immediately before and immediately after the first dose of indomethacin and 24 h later before and after the third dose. The same recording schedule was used for the control infants. The effects of indomethacin on quantity and quality of spontaneous motor activity were examined. RESULTS: A significant reduction in the quantity of several spontaneous movement patterns and an increase in the occurrence of rest periods were found following the first indomethacin administration (p < 0.01). Concerning the quality of general movements, a reduction in the speed was found (p < 0.05). Both effects were not found after the third indomethacin administration. CONCLUSION: In preterm infants with a PDA, treatment with indomethacin leads to a transient reduction in the quantity of spontaneous movement patterns and to a decrease in the speed of general movements. We recommend a cautious use of bolus indomethacin for the treatment of PDA.