Methods, systems and related compositions are provided to perform single-cell marking of a nucleic acid and/or protein in a sample based on in-cell or in-organelle barcoding of nucleic acid and/or protein complexes of the cell or organelle; the methods and systems herein described are configured to provide in-cell or in-organelle single-cell marked nucleic acid and/or protein complexes comprising a single-cell, cell-specific, or a single-cell organelle-specific marker.