A nitrocellulose slide (or nitrocellulose film slide) is a glass
microscope slide
A microscope slide is a thin flat piece of glass, typically 75 by 26 mm (3 by 1 inches) and about 1 mm thick, used to hold objects for examination under a microscope. Typically the object is mounted (secured) on the slide, and then ...
that is coated with
nitrocellulose
Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...
that is used to bind biological material, often
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
, for colorimetric and fluorescence detection assays. For this purpose, a nitrocellulose slide is generally considered to be superior to glass, because it binds a great deal more protein, and protects the
tertiary structure
Protein tertiary structure is the three-dimensional shape of a protein. The tertiary structure will have a single polypeptide chain "backbone" with one or more protein secondary structures, the protein domains. Amino acid side chains and the ...
of the protein (and other biological material, i.e.: cells). Typically, nitrocellulose slides have a thin, opaque film of nitrocellulose on a standard 25mm × 75 mm glass
microscope slide
A microscope slide is a thin flat piece of glass, typically 75 by 26 mm (3 by 1 inches) and about 1 mm thick, used to hold objects for examination under a microscope. Typically the object is mounted (secured) on the slide, and then ...
. The film is extremely sensitive to contact, and to foreign material; contact causes deformation and deposition of material, especially liquids.
A nitrocellulose slide is different from a nitrocellulose membrane, which usually filters protein from solution (i.e.: physician's office
pregnancy test
A pregnancy test is used to determine whether a person is Pregnancy, pregnant or not. The two primary methods are testing for the pregnancy hormone (human chorionic gonadotropin (hCG)) in blood or urine using a pregnancy test kit, and scanning ...
s), but that it serves a similar goal: to detect the presence and/or concentration level of certain biological material.
Microarrays
Nitrocellulose slides are used mainly in
proteomics
Proteomics is the large-scale study of proteins. Proteins are vital macromolecules of all living organisms, with many functions such as the formation of structural fibers of muscle tissue, enzymatic digestion of food, or synthesis and replicatio ...
to do
protein microarray
A protein microarray (or protein chip) is a high-throughput method used to track the interactions and activities of proteins, and to determine their function, and determining function on a large scale. Its main advantage lies in the fact that larg ...
s with automated systems that print the slides and record results. Microarrays of cell analytes, arrays of
cell lysate,
antibody
An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as pathogenic bacteria, bacteria and viruses, includin ...
microarrays, tissue printing,
immunoarrays, etc. are also possible with the slide.
Nitrocellulose fluorescence
Due to their high surface roughness, conventional white nitrocellulose films scatter and reflect large amounts of excitation and emission light during the fluorescence detection in the microarray scanner. In addition, nitrocellulose exhibits a natural autofluorescence at the detection wavelengths commonly used.
Both these factors lead to a high background fluorescent signal from these membrane slides. To overcome this problem, a new process has been developed to generate black membranes that absorb the scattered light, significantly reducing the background auto-fluorescence and thus offering a very low and homogenous auto-fluorescence to achieve a significantly improved dynamic range.
These slides are commercially available through
Schott AG
Schott AG is a German multinational glass company specializing in the manufacture of glass and glass-ceramics. Headquartered in Mainz, Rhineland-Palatinate, Germany, it is owned by the Carl Zeiss foundation, Carl Zeiss Foundation. The company's ...
.
Nevertheless, conventional white nitrocellulose films continue to be the dominant surface for many protein microarray applications because the claims above have not proved relevant to end user requirements. Regardless, nitrocellulose slide manufacturers like
Grace Bio-Labs continue to develop new nitrocellulose surfaces to further optimize their use in protein microarrays.
A method for protein quantitation on nitrocellulose coated glass slides uses
near-IR fluorescent detection with
quantum dot
Quantum dots (QDs) or semiconductor nanocrystals are semiconductor particles a few nanometres in size with optical and electronic properties that differ from those of larger particles via quantum mechanical effects. They are a central topic i ...
s. Traditional porous nitrocellulose signal to noise is limited by auto-fluorescence of the nitrocellulose at the respective required wavelengths of excitation and emission for standard organic fluorescent detection probes. Near IR detection probes are excited and read at emission wavelengths outside the range of nitrocellulose fluorescence.
[Marie‐Laure Schneider, Adriana Marquez‐ Lagraulet, Richard Pasquesi, Michael Shultz - (2014)]
"Infrared detection decreases nitrocellulose auto-fluorescence and improves RPPA assays signal‐to‐noise ratio over visible wavelength detection", Innopsys Inc. Chicago, Illinois
References
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Microscopy
Biochemistry methods