The present invention relates to substrates for biological testing produced from photo-curable epoxy compositions which further include carboxyl-containing monomers such as acrylic acid, 2-carboxyethyl acrylic acid, 4-vinylbenzoic acid, or 3-Acrylamido-3-methyl-1-butanoic acid, or glycidyl methacrylate, etc. The photo-curable compositions may be used to cast films or fabricate beads, magnetic beads, or magnetic beads containing nickel barcodes. The resulting various kinds of films, beads, magnetic beads, or magnetic beads containing nickel barcodes may find use in clinical or biological applications.