ABSTRACT
Lipophilic components are known to modulate the process of bioadhesion on the tooth surface. However, the presence of lipid droplets at the acquired pellicle under oral conditions has not been demonstrated, yet. The purpose of the present study was to establish a method for direct visualisation of lipids on the surface of hydrated, pellicle covered tooth samples by environmental scanning electron microscopy (ESEM), and to use this technique for studying the effects of rinsing with edible oils on the acquired pellicle under in vivo conditions. In situ pellicle formation was performed by 3 min exposure of enamel and dentin specimens in the oral cavity of volunteers. Subsequently, the volunteers rinsed in vivo with safflower oil or linseed oil for 30 s, and the specimens were further carried intraorally for periods from 0 min up to several hours. After intraoral exposure the specimens were treated by osmium tetroxide vapour, and were subsequently analysed by ESEM. This technique was capable to directly visualise the presence of lipid droplets at the pellicle's surface under hydrated conditions. ESEM analyses revealed that surface bound nano- and micro-sized lipid droplets were present at the acquired pellicle's surface even several hours after rinsing with edible oils indicating that these droplets had tightly adhered to the pellicle surface. Pellicle modification by edible oil rinsing as demonstrated in the present study might have the potential to be beneficial as an adjunct in dental prophylaxis.
Subject(s)
Dental Pellicle/ultrastructure , Dietary Fats, Unsaturated/administration & dosage , Microscopy, Electron, Scanning/methods , Adult , Animals , Bacteria , Bacterial Adhesion , Biofilms , Cattle , Dental Enamel/microbiology , Dental Pellicle/microbiology , Dentin/microbiology , Healthy Volunteers , Humans , Surface Properties , Tooth/microbiology , Tooth/ultrastructureABSTRACT
Silicon microchips with thin, electron transparent silicon nitride windows provide a sample support that accommodates both light-, and electron microscopy of whole eukaryotic cells in vacuum or liquid, with minimum sample preparation steps. The windows are robust enough that cellular samples can be cultured directly onto them, with no addition of a supporting film, and there is no need to embed or section the sample, as is typically required in electron microscopy. By combining two microchips, a microfluidic chamber can be constructed for the imaging of samples in liquid in the electron microscope. We provide microchip design specifications, a fabrication outline, instructions on how to prepare the microchips for biological samples, and examples of images obtained using different light and electron microscopy modalities. The use of these microchips is particularly advantageous for correlative light and electron microscopy.
Subject(s)
Biomedical Research/methods , Microscopy, Electron/methods , Silicon Compounds/chemistry , Animals , COS Cells , Chlorocebus aethiops , Microfluidics/methodsABSTRACT
Single gold-tagged epidermal growth factor (EGF) molecules bound to cellular EGF receptors of fixed fibroblast cells were imaged in liquid with a scanning transmission electron microscope (STEM). The cells were placed in buffer solution in a microfluidic device with electron transparent windows inside the vacuum of the electron microscope. A spatial resolution of 4 nm and a pixel dwell time of 20 micros were obtained. The liquid layer was sufficiently thick to contain the cells with a thickness of 7 +/- 1 microm. The experimental findings are consistent with a theoretical calculation. Liquid STEM is a unique approach for imaging single molecules in whole cells with significantly improved resolution and imaging speed over existing methods.
