TY - JOUR A1 - Zhao, Shuang A1 - Yue, Zhao A1 - Zhu, Dingcheng A1 - Harberts, Jann A1 - Blick, Robert H. A1 - Zierold, Robert A1 - Lisdat, Fred A1 - Parak, Wolfgang J. T1 - Quantum Dot/TiO2 Nanocomposite-Based Photoelectrochemical Sensor for Enhanced H2O2 Detection Applied for Cell Monitoring and Visualization JF - Small N2 - This work exploits the possibility of using CdSe/ZnS quantum dot (QD)-electrodes to monitor the metabolism of living cells based on photoelectrochemical (PEC) measurements. To realize that, the PEC setup is improved with respect to an enhanced photocurrent signal, better stability, and an increased signal-to-noise ratio, but also for a better biocompatibility of the sensor surface on which cells have been grown. To achieve this, a QD-TiO2 heterojunction is introduced with the help of atomic layer deposition (ALD). The heterojunction reduces the charge carrier recombination inside the semiconductor nanoparticles and improves the drift behavior. The PEC performance is carefully analyzed by adjusting the TiO2 thickness and combining this strategy with multilayer immobilizations of QDs. The optimal thickness of this coating is ≈5 nm; here, photocurrent generation can be enhanced significantly (e.g., for a single QD layer electrode by more than one order of magnitude at 0 V vs Ag/AgCl). The resulting optimized electrode is used for hydrogen peroxide (H2O2) sensing with a good sensitivity down to µmolar concentrations, reusability, stability, response rate, and repeatability. Finally, the sensing system is applied to monitor the activity of cells directly grown on top of the electrode surface. KW - biocompatible interface with atomic layer deposition KW - biosensor KW - detection of cellular metabolism KW - light addressable potentiometric sensor KW - photocurrent measurements Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-19642 VL - 20 IS - 45 PB - Wiley ER - TY - JOUR A1 - Matuschek, Nelson A1 - Liebscher, Thilo A1 - Santo, Loredana A1 - Foitzik, Andreas T1 - Online Glucose Measurement in DMEM for In Vitro Cell Culture JF - Materials Science Forum N2 - In-vitro cell culture offers the ability to grow individual cells and monitor their behaviour in a controlled environment over a certain time. During culture, different parameters have to be controlled to ensure a vital growth of cells. The most important parameters are temperature, pH-value, oxygen and carbon dioxide levels as well as the glucose concentration. All of these parameters influence the growth ability of the cell culture and should be monitored online. The online monitoring of glucose was achieved with a novel GOD based sensor which enabled a real-time measurement of glucose during cell culture. A first-time characterisation of the sensor was carried out in the culture medium DMEM. In addition, material properties of the culture system were investigated. At first to establish a baseline measurement, the sensor was placed in different glucose concentrations dissolved in Water-KCl mixture at 25 °C inside a batch chamber under constant stirring. Afterwards, the temperature was increased to 37 °C to simulate a cell culture environment. In addition, the system was transferred into a flow-through reaction chamber. The highest response signal and the most stable signal was achieved at 37 °C with DMEM during flow-through measurement. Based on these measurements online glucose monitoring in cell culture was possible to determine the glucose consumption for each cell which is important for future human-on-a-chip devices to prevent diabetic metabolisms. KW - biosensor KW - cell culture KW - cell KW - micro-reactor KW - online glucose monitoring Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-18734 SN - 0255-5476 SN - 1662-9752 VL - 941 SP - 2501 EP - 2506 PB - Trans Tech Publications ER - TY - JOUR A1 - Steglich, Patrick A1 - Lecci, Giulia A1 - Mai, Andreas T1 - Surface Plasmon Resonance (SPR) Spectroscopy and Photonic Integrated Circuit (PIC) Biosensors: A Comparative Review JF - Sensors N2 - Label-free direct-optical biosensors such as surface-plasmon resonance (SPR) spectroscopy has become a gold standard in biochemical analytics in centralized laboratories. Biosensors based on photonic integrated circuits (PIC) are based on the same physical sensing mechanism: evanescent field sensing. PIC-based biosensors can play an important role in healthcare, especially for point-of-care diagnostics, if challenges for a transfer from research laboratory to industrial applications can be overcome. Research is at this threshold, which presents a great opportunity for innovative on-site analyses in the health and environmental sectors. A deeper understanding of the innovative PIC technology is possible by comparing it with the well-established SPR spectroscopy. In this work, we shortly introduce both technologies and reveal similarities and differences. Further, we review some latest advances and compare both technologies in terms of surface functionalization and sensor performance. KW - surface plasmon resonance KW - photonic integrated circuit KW - biosensor KW - surface functionalization KW - label-free detection Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-16018 SN - 1424-8220 VL - 22 IS - 8 PB - MDPI ER - TY - JOUR A1 - Steglich, Patrick A1 - Hülsemann, Marcel A1 - Dietzel, Birgit A1 - Mai, Andreas T1 - Optical Biosensors Based on Silicon-On-Insulator Ring Resonators: A Review JF - Molecules N2 - Recent developments in optical biosensors based on integrated photonic devices are reviewed with a special emphasis on silicon-on-insulator ring resonators. The review is mainly devoted to the following aspects: (1) Principles of sensing mechanism, (2) sensor design, (3) biofunctionalization procedures for specific molecule detection and (4) system integration and measurement set-ups. The inherent challenges of implementing photonics-based biosensors to meet specific requirements of applications in medicine, food analysis, and environmental monitoring are discussed. KW - biosensor KW - biophotonics KW - integrated optical sensor KW - aptamer KW - biomaterial KW - optical sensor KW - silicon photonics KW - ring resonator KW - lab-on-a-chip Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-10822 SN - 1420-3049 VL - 24 IS - 3 ER - TY - JOUR A1 - Wegerich, F. A1 - Turano, Paola A1 - Allegrozzi, Marco A1 - Möhwald, H. A1 - Lisdat, Fred T1 - Superoxide Biosensing with Engineered Cytochrome c JF - Procedia Chemistry N2 - Several mutation positions have been chosen for introducing positively charged lysines in human cytochrome c (cyt c) with the aim of increasing the reaction rate with superoxide radicals (SO) and thus, the sensitivity of an electrochemical cyt c based SO biosensor. The impact of the mutations on structural and redox properties as well as on the reaction rate with SO are verified. Four mutants show a higher reaction rate with the radical compared to the wild type. These mutants are used for the construction of SO sensors based on thiol-modified gold electrodes and covalently fixed proteins. The E66K mutant electrode has a clearly higher sensitivity in comparison to the wildtype based sensor. KW - biosensor KW - cytochrome c KW - superoxide KW - protein engineering Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-6523 SN - 1876-6196 VL - 1 IS - 1 SP - 1287 EP - 1290 ER -