NANOGOLD® LABELING REAGENTS
Nanogold® is a better gold label. The 1.4 nm Nanogold® particle is a gold compound: it is not just adsorbed to proteins, like colloidal gold, but covalently reacts at specific sites under mild buffer conditions. This gives a well defined product that can be purified chromatographically.
Nanogold® brings the versatility of fluorescent conjugation to gold labeling. It may be used to label any molecule with a suitable reactive group: oligonucleotides, lipids, peptides, proteins, enzyme inhibitors and others, unlike colloidal gold which may be adsorbed only to antibodies and a limited range of proteins and peptides. Nanogold® is small and highly uniform in size, in sharp contrast to small colloidal gold preparations (most commonly used "1 nm" golds actually range from 1 to 3 nm). Nanogold® is available both as a labeling reagent for labeling your own biomolecules and in a range of antibody IgG, Fab' and streptavidin conjugates.
Although 1.4 nm Nanogold® is smaller than most other EM probes, it can easily be enhanced with silver (LI Silver or HQ Silver) by brief exposure (1 - 5 min.) to produce highly visible grains 2-20 nm in size (depending on development time). Further development (8-25 min.) gives a black signal easily seen in the light microscope and on immunoblots, polyacrylamide gels and Western blots.
Nanogold® labeling reagents are now available in three different packages: 30 nmol for larger labeling experiments, 5 X 6 nmol for several smaller labeling experiments, or in single 6 nmol vials so you can try these reagents on a smaller scale for a low price.
Features of Nanogold®
- Unparalleled penetration of conjugates up to 40 µm.
- Higher density of immunolabeling than with larger gold probes.
- Can be conjugated to any molecule with a suitable reactive group. Available with different reactivities.
- Extremely uniform 1.4 nm gold particle.
- Label at specific sites which do not obstruct native reactivity.
- Close to stoichiometric labeling.
- Reacts under mild, neutral conditions.
- Conjugates are easily isolated by gel filtration.
- Conjugates are stable to a wide range of pH and ionic strengths.
- High stability: conjugates show unchanged reactivity after storage for a year.
NANOGOLD®-ANTIBODY CONJUGATES
Nanogold® is a better gold label. The 1.4 nm Nanogold® particle is a gold compound: it is not just adsorbed to proteins, like colloidal gold, but covalently reacts at specific sites under mild buffer conditions.
The Nanogold® particle is covalently and specifically linked to a hinge thiol on Fab' or IgG. The conjugate therefore has excellent stability compared to colloidal gold-antibody preparations. It is the first probe offered as a Fab' conjugate, which is the smallest gold-antibody probe commercially available. These substantially smaller probes reach more antigens and provide better labeling. They can be viewed directly in TEM without silver enhancement or developed with silver to any appropriate size for enhanced visibility with other counterstains. Whereas the stoichiometry of conventional gold probes particles to IgG molecules varies from 0.2 to 10, Nanogold® preparations contain close to one Nanogold® to one Fab' or IgG.
Features of Nanogold® Conjugates
- Smallest commercially available gold immunoprobes.
- Penetrates and reaches antigens inaccessible to other probes: proven penetration up to 40 µm into
- Extremely uniform 1.4 nm diameter gold label.
- Fab', IgG and Streptavidin conjugates available.
- Close to 1 Nanogold® particle to 1 Fab' (or IgG).
- Low non-specific affinity gives minimal background.
- Ultrasensitivity with silver enhancement: 0.1 pg of antigen detection on immunoblots.
- Gold is covalently attached to antibody remote from antigen binding region.
- High stability and long shelf life: conjugates show unchanged reactivity after storage for a year.
- Stable to a wide range of pH and ionic strengths.
Ni-NTA-Nanogold®
Ni-NTA-Nanogold® is designed for detection or localization of polyhistidine (his) -tagged fusion proteins using electron microscopy, light microscopy or blotting. Using Ni-NTA-Nanogold®, his-tagged fusion proteins originating from any of a variety of expression vectors can be labeled under non-denaturing or denaturing conditions. The labeled his-tagged fusion proteins can be visualized by microscope or blots, when used with gold or silver enhancement reagents such as our Gold Enhance EM (Catalog number 2113), Gold Enhance LM (Catalog number 2112), or HQ Silver (Catalog Number 2012).
Ni-NTA-Nanogold® is designed for detection and localization of polyhistidine-tagged proteins using electron microscopy, light microscopy and blotting. Ni-NTA-Nanogold® comprises a 1.8 nm Nanogold particle with multiple nickel-nitrilotriacetic acid functionalities incorporated into the ligands on the surface of gold particles. Nickel-nitrilotriacetic acid functionalities bind to histidines from the tagged proteins, and form stable complexes with extremely low dissociation constants. Using Ni-NTA-Nanogold®, His-tagged fusion proteins originating from any of a variety of expression vectors can be labeled under both non-denaturing and denaturing conditions. By using silver or gold enhancement, The labeled his-tagged proteins can be visualized in the electron or light microscope and on blots.
Features of Ni-NTA-Nanogold®
- Detects and localizes His-tagged recombinant proteins in electron microscope, light microscope and blots.
- Good product stability.
- 1.8 nm diameter gold particle.
- High resolution for ultrastructural studies.
- Permanent stain does not fade.
