What is EnzMet?
Clearer, crisp staining for in situ hybridization (ISH)
and immunohistochemistry (IHC)
EnzMet (Enzyme Metallography) is a new biological labeling and staining method developed at Nanoprobes. It uses a targeted enzymatic probe with a novel metallographic substrate to provide a quantum leap in staining clarity over conventional chromogenic and fluorescent substrates.
EnzMet™ has proven highly sensitive both for in situ hybridization (ISH), where it readily visualizes endogenous copies of single genes, and immunohistochemistry (IHC) detection.
It has also been used as an electrical detection method and to create nanowires for biochips.
Comparison of EnzMet with conventional DAB immunohistochemistry and enhanced DAB, showing superior contrast and sensitivity even without further amplification. Cytokeratins in paraffin-embedded bladder tumor stained with monoclonal primary antibody (AE1/AE3, Dako) and peroxidase secondary (Envision, Dako).
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Features of EnzMet
Patented EnzMet technology uses HRP to deposit metallic silver with extraordinary selectivity.
High sensitivity: detect single copies of target genes, or low-abundance proteins with virtually no background.
Compatible with all counterstains: lets you clearly see surrounding tissue morphology (as opposed to fluorescent signals where surrounding tissue is not visible)
Minimal diffusion: super-high resolution compared with DAB.
Near zero background.
Does not fade or bleach.
The sharply resolved black signal is readily distinguished from other stains: it has been combined with fast red K immunohistochemistry to provide a concomitant brightfield gene and protein assay.
EnzMet has many advantages both over fluorescent labels and enzyme chromogens. Because it is used in the conventional brightfield microscope, it does not require fluorescent optics, or dark adaptation on the part of the user. The signal is permanent, and does not have the photobleaching problems associated with fluorescent stains.
EnzMet™'s high density enables visualization at even low magnification. It produces a sharp metal deposit that does not diffuse like DAB, giving higher resolution localizations. Because the deposited metal is electron-dense, it provides high contrast for electron microscopy, making enzyme metallography a potential correlative light and electron microscopy method.
Nanoprobes recently teamed with Ventana Medical Systems to create a definitive Her 2 breast cancer test based on EnzMet, using SISH (Silver In Situ Hybridization). Treatment for this disease was already quite effective, but a good test for it remained the missing link between detection and cure. The test is now being used across the United States and Europe, and Nanoprobes is very proud to be have been a part of this effort.
Human breast cancer biopsy tissue section where single copies (2 per normal cell) of the Her 2/neu gene were detected by EnzMet (black spots).
Better than FISH: EnzMet enables bright field detection, a permanent signal, and use of full-strength H&E staining for simultaneous visualization of underlying tissue morphology.
Original magnification x 400; courtesy of Dr. Raymond R. Tubbs, Cleveland Clinic Foundation.