Sensitive fluorescence detection of heparin based on self-assembly of mesoporous silica nanoparticle-gold nanoclusters with emission enhancement characteristics.

Heparin (Hep) is widely used as a major anticoagulant in surgery. Simple and sensitive methods capable of quantitative detection of Hep are desired for better regulating its clinical use. Herein, a novel nanoassembly of amino-functionalized mesoporous silica nanoparticle-gold nanoclusters (MSN-AuNCs) with remarkable emission enhancement characteristics for sensitive fluorescence detection of Hep is developed. The electrostatic interaction between the positively charged amino-functionalized MSNs and the AuNC-stabilizing surface ligands triggers the self-assembly of MSN-AuNC nanocomposites which exhibit more than 5-fold fluorescence emission enhancement. However, the presence of negatively charged Hep inhibits the emission enhancement phenomenon due to the effective wrapping of Hep on the surface of MSNs, which blocks the interaction between AuNCs and MSNs. Benefitting from the remarkable emission enhancement and the competing binding of Hep, facile and ultrasensitive detection of Hep can be realized with a detection limit as low as 2 nM. Moreover, the successful application of the proposed method for detection of Hep in human serum samples shows promise for clinical applications.