As reported by Borghei et al., a label-free system consisting of DNA aptamers conjugated to CdTe QDs can detect HER2 biomarkers in adhesive cells and cells suspended in complex environments (in serum samples), as well as in tumor samples, with a linear range of 15 to 1.5 million cells/mL [178]. The gene discussed is ERBB2; the disease is neoplasm.