Protein-Protected Au Clusters as a New Class of Nanoscale Biosensor for Label-Free Fluorescence Detection of Proteases

The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA.
Small (Impact Factor: 7.51). 12/2012; 8(24):3769-3773. DOI: 10.1002/smll.201201983
Source: PubMed

ABSTRACT Destruction for detection: Protein-protected Au clusters are exploited as nanoscale sensors for label-free fluorescence detection of proteases with high sensitivity. The detection mechanism is based on degradation of the protein shell by a protease, allowing the O(2) from ambient air to penetrate through and quench the fluorescence from the Au cluster.

  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel label-free fluorescent biosensor platform has been developed for protease activity assay using peptide-templated gold nanoclusters (AuNCs). The biosensor was demonstrated with elastase as the model to have high sensitivity, excellent specificity, simplicity and rapidity.
    RSC Advances 01/2014; 4(27):13753. DOI:10.1039/c4ra00096j · 3.71 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A facile one-pot strategy was developed for the synthesis of lysozyme functionalized fluorescence gold nanoclusters (AuNCs). The lysozymes added to reduce Au3+ ions and stabilize the AuNCs during the synthesis were coated on the AuNCs surface and retained their specific recognition ability for bacteria such as Escherichia coli (E. coli). Based on such ability, these AuNCs were specifically attached onto the surface of E. coli, which resulted in great red fluorescence enhancement. Nevertheless, the bovine serum albumin (BSA) stabilized AuNCs could not recognize E. coli and no fluorescence enhancement was observed. Upon the addition of E. coli, the red fluorescence intensity of lysozyme-AuNCs was enhanced linearly over the range of 2.4×104 −6.0×106 CFU/mL of E. coli with high sensitivity (LOD=2.0×104 CFU/mL, S/N=3). The visualization fluorescence evolution may enable the rapid and real-time detection of bacteria. This study may be extended to other functional proteins such as antibody, enzyme, and peptide functionalized nanoclusters while retaining the bioactivity of coating proteins and find wide applications in the fields of biochemistry and biomedicine.
    Talanta 11/2014; 134. DOI:10.1016/j.talanta.2014.10.058 · 3.51 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Blot-based technology is widely used in biomedical research, serving as a remarkably efficient platform for biomolecule recognition and detection. In this report, highly fluorescent gold nanoclusters have been synthesized under mild conditions by using a proteolytic enzyme, α-chymotrypsin A (CTRA), as both the stabilizing and reducing agents. The synthesized AuNCs@CTRA was characterized by various techniques including UV-vis absorption, fluorescence, X-ray photoelectron spectroscopy and TEM. The fluorescent AuNCs@CTRA is fairly stable and responsive to mercury ions with high selectivity and sensitivity. These protein capped nanoclusters were electrophoresed on an SDS-PAGE gel and transferred to a cellulose membrane. Mercury ions can specifically quench the red fluorescent AuNCs@CTRA band and selectively stop the green band formation on the membrane through inhibition of the peroxidase mimic activity of AuNCs@CTRA toward the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) substrate in a concentration dependent manner. Therefore, using a blot-technology based system, we demonstrated the operation of the AuNCs@CTRA-cellulose hybrid material for mercury ion visual sensing that can be dually read out under UV light (fluorometric) and the naked eye (colorimetric). This approach also has potential for use in other blot-technology based applications.
    RSC Advances 01/2014; 4(60):31536. DOI:10.1039/C4RA05686H · 3.71 Impact Factor


Available from
May 17, 2014