A polyelectrolyte having multiple exposed functional groups, each such group being capable of covalently bonding to a molecule, is immobilized on a surface for the purpose of bonding to a biomolecule. The biomolecule can be, for example, a nucleic acid, e.g., an amine functionalized oligonucleotide. The polyelectrolyte can include, e.g., BSA (Bovine Serum Albumin) which is bound to a functionalized surface using a covalent immobilization strategy, e.g., reaction with the surface of a tosyl-activated microparticle. Following such reaction, exposed reactive functional groups on the protein, such as amine, carboxyl, thiol, hydroxyl groups can further be utilized to covalently couple the oligonucleotide of interest using suitable chemistry.