What are the alternatives to the BCA assay if there are any?

Yes, there are several alternatives to the BCA assay. One alternative is the Biuret assay, which is a straightforward and cost-effective method for protein quantification. It involves a reaction between proteins and Biuret reagent, which contains copper ions. The presence of proteins leads to a color change due to the formation of a complex with the copper ions. Another alternative is the Lowry assay, which builds upon the Biuret method by adding a second step involving the Folin–Ciocalteu reagent. This additional step significantly increases the sensitivity of the assay. A third alternative is the Bradford assay, which uses Coomassie Brilliant Blue dye, to bind to protein and change color. The intensity of the color change is proportional to the protein concentration.