In this work we designed, synthesized and characterized luminescent metal nanoclusters (NCs) on human serum albumin (HSA) and immunoglobulins (Ig). We demonstrate that the approach developed allows one to determine the relative content of albumins and immunoglobulins in biologically relevant protein mixtures based on the luminescent properties of the NCs. Fast and inexpensive approach which allows to determine concentrations of immunoglobulins (Ig) and serum albumin (HSA) in blood serum might be useful in clinical diagnostics.