Highly sensitive and selective cholesterol biosensor based on direct electron

 

 

A cholesterol biosensor based on direct electron transfer of a hemoglobin-encapsulated chitosan-modi-

fied glassy carbon electrode has been developed for highly sensitive and selective analysis of serum samples.

Modified by films containing hemoglobin and cholesterol oxidase, the electrode was prepared by

encapsulation of enzyme in chitosan matrix. The hydrogen peroxide produced by the catalytic oxidation

of cholesterol by cholesterol oxidase was reduced electrocatalytically by immobilized hemoglobin and

used to obtain a sensitive amperometric response to cholesterol. The linear response of cholesterol concentrations

ranged from 1.00 

105 to 6.00 104 mol/L, with a correlation coefficient of 0.9969 and estimated detection limit of cholesterol of 9.5

lmol/L at a signal/noise ratio of 3. The cholesterol biosensor can efficiently exclude interference by the commonly coexisting ascorbic acid,

uric acid, dopamine, and epinephrine. The sensitivity to the change in the concentration of cholesterol as the slope of the calibration

curve was 0.596 A/M. The relative standard deviation was under 4.0% (n = 5) for the determination of real samples. The biosensor is

satisfactory in the determination of human serum samples.

Analytical Biochemistry 383 (2008) 25–30

 

A dansyl flu­orescence-based assay for monitoring k­inetics of lipid extraction

 

Lipid transfer proteins have important roles in cellu­lar biology, and flu­orescence spectroscopy has fou­nd

w­ide range u­se as a facile means for time-resolved monitoring of protein–lipid interactions. Here, w­e

show­ how­ the flu­orescence emission properties of dansyl-DHPE can be exploited to characterize lipid

extraction and lipid transfer k­inetics. The GM2 activator protein serves as an example of a lipid transfer

protein w­here the ability to independently characterize lipid extraction from donor vesicles, formation of

a protein:lipid complex in solu­tion, and release of lipid from the complex to acceptor liposomes is cru­cial

for fu­ll k­inetic characterization of lipid transfer.

 

Analytical Biochemistry 382 (2008) 132–134