Turbidimetry is the process of measuring the loss of intensity of transmitted light due to scattering effect of particles suspended in it. We believe OptiLink particles to be the best overall choice for immunoassay reagent development. The acid content of OptiLink is a very important criterion in particle selection. Implicit in this statement is the belief that covalent coupling is preferable to adsorption alone for binding proteins to particles. The reasons for this are that OptiLink carboxylate modified particles:
1. Adsorb protein more efficiently than plain polystyrene particles (adsorption precedes covalent coupling to particle).
2. Give you a choice of surface acid content, which allows you to match your protein to the best particle for that protein (both in terms of total adsorption and colloidal stability).
3. Permit adjustment of the colloidal properties through surface charge. Carboxyl groups can be neutralized, converted to a positive charge, or reacted to form covalent bonds to protein. If left as carboxyl groups, the charge can be adjusted by changing the pH of the storage or reaction buffer.
4. Insure little or no leaching of bound protein with:
- Extended time
- Changes in pH
- Changes in ionic strength
5. Greater flexibility: Covalent coupling with carboxyl-modified microparticles gives greater flexibility in the formulation of storage and reaction buffers.