TY  - JOUR
A1  - Prüfer, Mareike
A1  - Wenger, Christian
A1  - Bier, Frank Fabian
A1  - Laux, Eva-Maria
A1  - Hölzel, Ralph
T1  - Activity of AC electrokinetically immobilized horseradish peroxidase
JF  - Electrophoresis : microfluidics, nanoanalysis & proteomics
N2  - Dielectrophoresis (DEP) is an AC electrokinetic effect mainly used to manipulate cells. Smaller particles, like virions, antibodies, enzymes, and even dye molecules can be immobilized by DEP as well. In principle, it was shown that enzymes are active after immobilization by DEP, but no quantification of the retained activity was reported so far. In this study, the activity of the enzyme horseradish peroxidase (HRP) is quantified after immobilization by DEP. For this, HRP is immobilized on regular arrays of titanium nitride ring electrodes of 500 nm diameter and 20 nm widths. The activity of HRP on the electrode chip is measured with a limit of detection of 60 fg HRP by observing the enzymatic turnover of Amplex Red and H2O2 to fluorescent resorufin by fluorescence microscopy. The initial activity of the permanently immobilized HRP equals up to 45% of the activity that can be expected for an ideal monolayer of HRP molecules on all electrodes of the array. Localization of the immobilizate on the electrodes is accomplished by staining with the fluorescent product of the enzyme reaction. The high residual activity of enzymes after AC field induced immobilization shows the method's suitability for biosensing and research applications.
KW  - AC electrokinetics
KW  - dielectrophoresis
KW  - enzyme activity
KW  - immobilization;
KW  - nanoelectrodes
Y1  - 2022
U6  - https://doi.org/10.1002/elps.202200073
SN  - 0173-0835
SN  - 1522-2683
SP  - 1920
EP  - 1933
PB  - Wiley
CY  - Hoboken
ER  -