L-tyrosine capped silver nanocluster: An efficient reusable luminescent nano-probe for simple, rapid and reliable detection of hemoglobin in real blood samples

Abstract

Easy and rapid quantification of hemoglobin (Hb) in the human body is essential for early screening of hematological disorders like anemia. Herein, we synthesized atomically precise tyrosine-protected photoluminescent silver nanocluster (Tyr-Ag NC) in a facile one-pot method. The synthesized nanocluster showed strong photoluminescence (PL) intensity peaked at 410 nm that can be selectively turned off by Hb with utmost sensitivity (limit of detection = 30 pM), thereby making the nanocluster a promising nano-probe for the detection of Hb. The observed PL quenching can be attributed to a complexation followed by a static charge transfer transition between the nanocluster and hemin, the cofactor of Hb involving both Fe2+ and the porphyrin ligand. The Fe2+ plays a key role in the complex formation which was disrupted by the formation of hydroxyl radicals through the Fe2+-H2O2 mediated Fenton reaction, restoring the PL intensity of the Tyr-Ag NC, ensuring its reusability for the detection of Hb. Compared to the conventional clinical techniques involving toxic chemicals and/or expensive equipment, the synthesized Tyr-Ag NC allows quick, direct, easy, accurate and cost-effective detection and quantification of Hb in real human serum and blood samples suggesting its tremendous practical applications for healthcare assessment.