TY  - JOUR
A1  - Zhang, Xiaorong
A1  - Caserta, Giorgio
A1  - Yarman, Aysu
A1  - Supala, Eszter
A1  - Tadjoung Waffo, Armel Franklin
A1  - Wollenberger, Ulla
A1  - Gyurcsanyi, Robert E.
A1  - Zebger, Ingo
A1  - Scheller, Frieder W.
T1  - "Out of Pocket" protein binding
BT  - a dilemma of epitope imprinted polymers revealed for human hemoglobin
JF  - Chemosensors
N2  - The epitope imprinting approach applies exposed peptides as templates to synthesize Molecularly Imprinted Polymers (MIPs) for the recognition of the parent protein. While generally the template protein binding to such MIPs is considered to occur via the epitope-shaped cavities, unspecific interactions of the analyte with non-imprinted polymer as well as the detection method used may add to the complexity and interpretation of the target rebinding. To get new insights on the effects governing the rebinding of analytes, we electrosynthesized two epitope-imprinted polymers using the N-terminal pentapeptide VHLTP-amide of human hemoglobin (HbA) as the template. MIPs were prepared either by single-step electrosynthesis of scopoletin/pentapeptide mixtures or electropolymerization was performed after chemisorption of the cysteine extended VHLTP peptide. Rebinding of the target peptide and the parent HbA protein to the MIP nanofilms was quantified by square wave voltammetry using a redox probe gating, surface enhanced infrared absorption spectroscopy, and atomic force microscopy. While binding of the pentapeptide shows large influence of the amino acid sequence, all three methods revealed strong non-specific binding of HbA to both polyscopoletin-based MIPs with even higher affinities than the target peptides.
KW  - Molecularly Imprinted Polymers
KW  - epitope imprinting
KW  - non-specific
KW  - binding
KW  - redox gating
KW  - SEIRA spectroelectrochemistry
Y1  - 2021
U6  - https://doi.org/10.3390/chemosensors9060128
SN  - 2227-9040
VL  - 9
IS  - 6
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Tadjoung Waffo, Armel Franklin
A1  - Mitrova, Biljana
A1  - Tiedemann, Kim
A1  - Iobbi-Nivol, Chantal
A1  - Leimkühler, Silke
A1  - Wollenberger, Ulla
T1  - Electrochemical trimethylamine n-oxide biosensor with enzyme-based oxygen-scavenging membrane for long-term operation under ambient air
JF  - Biosensors : open access journal
N2  - An amperometric trimethylamine N-oxide (TMAO) biosensor is reported, where TMAO reductase (TorA) and glucose oxidase (GOD) and catalase (Cat) were immobilized on the electrode surface, enabling measurements of mediated enzymatic TMAO reduction at low potential under ambient air conditions. The oxygen anti-interference membrane composed of GOD, Cat and polyvinyl alcohol (PVA) hydrogel, together with glucose concentration, was optimized until the O-2 reduction current of a Clark-type electrode was completely suppressed for at least 3 h. For the preparation of the TMAO biosensor, Escherichia coli TorA was purified under anaerobic conditions and immobilized on the surface of a carbon electrode and covered by the optimized O-2 scavenging membrane. The TMAO sensor operates at a potential of -0.8 V vs. Ag/AgCl (1 M KCl), where the reduction of methylviologen (MV) is recorded. The sensor signal depends linearly on TMAO concentrations between 2 mu M and 15 mM, with a sensitivity of 2.75 +/- 1.7 mu A/mM. The developed biosensor is characterized by a response time of about 33 s and an operational stability over 3 weeks. Furthermore, measurements of TMAO concentration were performed in 10% human serum, where the lowest detectable concentration is of 10 mu M TMAO.
KW  - trimethylamine N-oxide
KW  - biosensor
KW  - TMAO-reductase
KW  - oxygen scavenger
KW  - immobilized enzyme
KW  - multienzyme electrode
KW  - viologen
Y1  - 2021
U6  - https://doi.org/10.3390/bios11040098
SN  - 2079-6374
VL  - 11
IS  - 4
PB  - MDPI
CY  - Basel
ER  -