Article ID Journal Published Year Pages File Type
7233036 Biosensors and Bioelectronics 2014 25 Pages PDF
Abstract
In this study, we generated gold nanoclusters (AuNCs) using inexpensive chicken egg white proteins (AuNCs@ew) as reagents. AuNCs@ew were generated by reacting aqueous tetrachloroauric acid with diluted chicken egg white under microwave heating (90 W) through subsequent heating cycles (5 min/cycle). Within 10 cycles, red photoluminescent AuNCs@ew with maximum emission wavelength at ~640 nm (λex=370 nm) were obtained. The quantum yield of the as-generated AuNCs was ~6.6%. The intact and the tryptic digest of AuNCs@ew were characterized by mass spectrometry. The results showed that the AuNCs@ew were mainly derived from ovalbumin, i.e., the major protein in egg white, encapsulated AuNCs. The AuNCs@ew also has the common features found in AuNCs@protein, which is sensitive to the presence of heavy metal ions such as Cu2+. The photoluminescence of the AuNCs@ew was quenched with the addition of Cu2+. Furthermore, the photoluminescence of the quenched AuNCs@ew can be restored in the presence of the molecules containing phosphate functional groups because of the strong binding affinity between Cu2+ and phosphates. We used the AuNCs@ew-Cu2+ conjugates as switch-on sensing probes for the detection of phosphate containing metabolites such as adenosine-5′-triphosphate (ATP) and pyrophosphate (PPi). The results showed that the photoluminescence of the sensing probes increased as the concentration of the phosphate-containing molecules in the sample solution increased. The limits of detection achieved using the AuNCs@ew-Cu2+ for ATP and PPi were ~19 and ~5 μM, respectively. Additionally, we also demonstrated the feasibility of using the AuNCs@ew as the sensing probes for lectins such as concanavalin A (Con A) based on the molecular recognitions between the glycan ligands on the AuNCs@ew and glycan binding sites on Con A.
Related Topics
Physical Sciences and Engineering Chemistry Analytical Chemistry
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