BeaverBeads Magrose NHS Pre-Activated Magnetic Agarose Beads

Product Overview

BeaverBeads™ Magrose NHS are superparamagnetic agarose microspheres whose surface is already activated with N-hydroxysuccinimide esters. NHS esters react directly with primary amines to form stable amide bonds, so any ligand carrying an accessible amine — antigen, antibody, protein, peptide or amine-modified oligonucleotide — can be immobilised without an activation step of your own.

That is the practical difference from carboxyl or amino beads. There is no EDC/NHS activation and no glutaraldehyde chemistry to run first, and no window in which activated beads have to be used before they hydrolyse. You dissolve the ligand in an amine-free coupling buffer, mix with the beads for 1–2 hours at room temperature or 4 °C, block, and you are done.

Specification

Ligand density is 20–30 µmol of NHS per mL of beads, and the manufacturer quotes a binding capacity of 20–30 mg of rabbit IgG per mL of beads — a reference figure, since capacity depends on the ligand. Coupling efficiency is stated at over 90% under optimised conditions, in 1–2 hours, at pH 5–9 and either room temperature or 4 °C. Note the 20% (v/v) suspension: 1 mL of what you pipette contains 200 µL of beads.

Coupling in outline

Prepare the protein solution in an amine-free buffer; wash the beads quickly with cold wash buffer; couple the protein; block residual NHS groups; wash into storage buffer. Blocking uses the 3 M ethanolamine supplied in the kit format, or 100 mM Tris-HCl with 150 mM NaCl at pH 8.0. After coupling, the bead concentration is 10% (v/v). Two optimisations matter: the choice of coupling buffer (coupling buffer A or B, 50 mM boric acid, 100 mM NaCl pH 7.4 are the candidates BEAVER lists), and the protein concentration — higher concentration couples more protein because NHS coupling competes with NHS hydrolysis, so it is a cost-versus-loading decision.

Applications

In vitro diagnostics and immunoassay development, immunoprecipitation and co-immunoprecipitation, cell sorting, and isolation and purification of proteins and antibodies.

Critical handling notes

The beads are water-sensitive. NHS esters hydrolyse on contact with water, which is why the wash step must be fast and use chilled buffer. Reseal the bottle immediately after sampling, tape the cap, and store at 4 °C.

The coupling buffer must contain no free amine. Any primary amine in the buffer competes with your ligand and consumes the activated sites.

Do not quantify coupled protein at 280 nm. NHS groups absorb strongly near 280 nm and will seriously distort the reading. Use a colorimetric assay instead — BEAVER cites the Pierce 660 nm protein assay or micro BCA.

Protein stabilisers block coupling. BSA and gelatin in an antibody preparation will compete for the NHS sites. Buffer-exchange the antibody before coupling.

Do not dry or freeze the beads; both cause aggregation and loss of binding activity. A magnetic separator is required. Keep beads and separators away from metal objects, electronic devices and implanted electronic devices such as cardiac pacemakers.

For Research Use Only. Not for use in diagnostic or therapeutic procedures. Specifications are those published by the manufacturer, BEAVER Biomedical Engineering Co., Ltd.