Colloidal gold preparations (suspensions of gold nanoparticles) in water are intensely red-colored, and can be made with tightly controlled particle sizes up to a few tens of nanometers across by reduction of gold chloride with citrate or ascorbate ions. Colloidal gold is used in research applications in medicine, biology and materials science. The technique of immunogold labeling exploits the ability of the gold particles to adsorb protein molecules onto their surfaces. Colloidal gold particles coated with specific antibodies can be used as probes for the presence and position of antigens on the surfaces of cells. In ultrathin sections of tissues viewed by electron microscopy, the immunogold labels appear as extremely dense round spots at the position of the antigen.Gold, or alloys of gold and palladium, are applied as conductive coating to biological specimens and other non-conducting materials such as plastics and glass to be viewed in a scanning electron microscope. The coating, which is usually applied by sputtering with an argon plasma, has a triple role in this application. Golds very high electrical conductivity drains electrical charge to earth, and its very high density provides stopping power for electrons in the electron beam, helping to limit the depth to which the electron beam penetrates the specimen. This improves definition of the position and topography of the specimen surface and increases the spatial resolution of the image.
Circumcision
Lidocaine/prilocaine eutectic mixture has been used during circumcision in newborn boys and has been considered efficacious and safe to lessen pain from circumcision.The European Medicines Agency concludes in its latest (2014) statement on Emla:
"Safety and efficacy for the use of EMLA on genital skin and genital mucosa have not been established in children younger than 12 years. Available paediatric data do not demonstrate adequate efficacy for circumcision. "The Patient Information Leaflet of EMLA in the UK states: "EMLA Cream should not be applied to the genital skin (e.g. penis) and genital mucosa (e.g. in the vagina) of children (below 12 years of age) owing to insufficient data on absorption of active
substances." Tempe
The spray is a combination of local anaesthetics lidocaine and prilocaine in a metered-dose aerosol that is sprayed directly on the penis to numb sensations. It was developed by the same group that invented the erectile dysfunction drug sildenafil. The drug was approved in Europe and was released in the UK market in November 2016 and within the EU will be marketed by, early in 2017 In the United States, the Food and Drug Administration (FDA) is expected to approve the drug in 2018. Compendial status
United States Pharmacopeia 31

See also
Dosage form
Eutectic point
Lidocaine
Prilocaine

References
External links
"Lidocaine mixture with Prilocaine". Drug Information Portal. U.S. National Library of Medicine.