TY  - JOUR
A1  - Molinnus, Denise
A1  - Beging, Stefan
A1  - Lowis, Carsten
A1  - Schöning, Michael Josef
T1  - Towards a multi-enzyme capacitive field-effect biosensor by comparative study of drop-coating and nano-spotting technique
JF  - Sensors
N2  - Multi-enzyme immobilization onto a capacitive field-effect biosensor by nano-spotting technique is presented. The nano-spotting technique allows to immobilize different enzymes simultaneously on the sensor surface with high spatial resolution without additional photolithographical patterning. The amount of applied enzymatic cocktail on the sensor surface can be tailored. Capacitive electrolyte-insulator-semiconductor (EIS) field-effect sensors with Ta2O5 as pH-sensitive transducer layer have been chosen to immobilize the three different (pL droplets) enzymes penicillinase, urease, and glucose oxidase. Nano-spotting immobilization is compared to conventional drop-coating method by defining different geometrical layouts on the sensor surface (fully, half-, and quarter-spotted). The drop diameter is varying between 84 µm and 102 µm, depending on the number of applied drops (1 to 4) per spot. For multi-analyte detection, penicillinase and urease are simultaneously nano-spotted on the EIS sensor. Sensor characterization was performed by C/V (capacitance/voltage) and ConCap (constant capacitance) measurements. Average penicillin, glucose, and urea sensitivities for the spotted enzymes were 81.7 mV/dec, 40.5 mV/dec, and 68.9 mV/dec, respectively.
Y1  - 2020
SN  - 1424-8220
U6  - http://dx.doi.org/10.3390/s20174924
N1  - Special issue: Multisensor Systems and Signal Processing in Analytical Chemistry
VL  - 20
IS  - 17
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Molinnus, Denise
A1  - Sorich, Maren
A1  - Bartz, Alexander
A1  - Siegert, Petra
A1  - Willenberg, Holger S.
A1  - Lisdat, Fred
A1  - Poghossian, Arshak
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Towards an adrenaline biosensor based on substrate recycling amplification in combination with an enzyme logic gate
JF  - Sensors and Actuators B: Chemical
N2  - An amperometric biosensor using a substrate recycling principle was realized for the detection of low adrenaline concentrations (1 nM) by measurements in phosphate buffer and Ringer’s solution at pH 6.5 and pH 7.4, respectively. In proof-of-concept experiments, a Boolean logic-gate principle has been applied to develop a digital adrenaline biosensor based on an enzyme AND logic gate. The obtained results demonstrate that the developed digital biosensor is capable for a rapid qualitative determination of the presence/absence of adrenaline in a YES/NO statement. Such digital biosensor could be used in clinical diagnostics for the control of a correct insertion of a catheter in the adrenal veins during adrenal venous-sampling procedure.
Y1  - 2016
U6  - http://dx.doi.org/10.1016/j.snb.2016.06.064
SN  - 0925-4005
VL  - 237
SP  - 190
EP  - 195
PB  - Elsevier
CY  - Amsterdam
ER  -