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348890 
Journal Article 
Picogram detection of metal ions by melanin-sensitized piezoelectric sensor 
Huang, GS; Wang, MT; Su, CW; Chen, YS; Hong, MY 
2007 
Yes 
Biosensors and Bioelectronics
ISSN: 0956-5663
EISSN: 1873-4235 
23 
3 
319-325 
English 
A heavy metal ion sensor was constructed by cross-linking melanin onto the gold electrode of quartz crystal microbalance (QCM). A mercury ion sensitivity of 518+/-37Hz/ppm was observed, a substantial increase in sensitivity compared to previous reports of 10-50Hz/ppm with the limit of detection at 5ppb. Detection of other metal ions including Sn super(2) super(+), Ge super(4) super(+), Li super(+), Zn super(2) super(+), Cu super(2) super(+), Bi super(3) super(+), Co super(2) super(+), Al super(3) super(+), Ni super(2) super(+), Ag super(+), and Fe super(3) super(+) were also performed. Unexpectedly, binding of Mn super(7) super(+), Pb super(2) super(+), Cd super(2) super(+), and Cr super(3) super(+) increased resonant frequencies. The surface profile of melanin thin film upon binding to metal ions was investigated by atomic force microscopy (AFM). Structural change of melanin upon binding to metal ions was characterized by circular dichroism and by infrared spectroscopy. The current study provides the first example of melanin-coated piezoelectric sensor showing high sensitivity and selectivity to metal ions. 
Article Subject Terms: Biosensors; C.D.; Chromium; Copper; Electrodes; Gold; Heavy metals; I.R. spectroscopy; Ions; Iron; Lead; Melanin; Mercury; Quartz crystal microbalance; Zinc; atomic force microscopy; W 30955 Biosensors