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Antibacterial activity of composite of graphene oxide with silver nanoparticles
(Mendel University in Brno, 2017-12-31) Bytešníková, Zuzana; Koudelková, Zuzana; Richtera, Lukáš; Kopel, Pavel; Adam, Vojtěch
Looking for strategies against the development of antibiotic resistance is a major global object of interest for the public health. This work deals with synthesis of antimicrobial composites of graphene oxide (GO) with metal nanoparticles. GO has been prepared by modified Hummers' method and characterized using scanning electron microscopy, Fourier transform infrared spectroscopy (FT-IR) and differential pulse voltammetry. Composites of GO have been synthetized with silve nanoparticles, which have been characterized. Potential antimicrobial activity of the nanocomposites was tested against Escherichia coli, Staphylococcus aureus and methicilin resistant Staphylococcus aureus (MRSA).
DEP-on-a-Chip: Dielectrophoresis Applied to Microfluidic Platforms
(MDPI, 2019-06-24) Zhang, Haoqing; Chang, Honglong; Neužil, Pavel
Dielectric particles in a non-uniform electric field are subject to a force caused by a phenomenon called dielectrophoresis (DEP). DEP is a commonly used technique in microfluidics for particle or cell separation. In comparison with other separation methods, DEP has the unique advantage of being label-free, fast, and accurate. It has been widely applied in microfluidics for bio-molecular diagnostics and medical and polymer research. This review introduces the basic theory of DEP, its advantages compared with other separation methods, and its applications in recent years, in particular, focusing on the different electrode types integrated into microfluidic chips, fabrication techniques, and operation principles.
High-Conductivity Stoichiometric Titanium Nitride for Bioelectronics
(Wiley-VCH GmbH, 2023-02-02) Gablech, Imrich; Migliaccio, Ludovico; Brodský, Jan; Havlíček, Marek; Podešva, Pavel; Hrdý, Radim; Ehlich, Jiří; Gryszel, Maciej; Glowacki, Eric Daniel
Bioelectronic devices such as neural stimulation and recording devices require stable low-impedance electrode interfaces. Various forms of nitridated titanium are used in biointerface applications due to robustness and biological inertness. In this work, stoichiometric TiN thin films are fabricated using a dual Kaufman ion-beam source setup, without the necessity of substrate heating. These layers are remarkable compared to established forms of TiN due to high degree of crystallinity and excellent electrical conductivity. How this fabrication method can be extended to produce structured AlN, to yield robust AlN/TiN bilayer micropyramids, is described. These electrodes compare favorably to commercial TiN microelectrodes in the performance metrics important for bioelectronics interfaces: higher conductivity (by an order of magnitude), lower electrochemical impedance, and higher capacitive charge injection with lower faradaicity. These results demonstrate that the Kaufman ion-beam sputtering method can produce competitive nitride ceramics for bioelectronics applications at low deposition temperatures.
Downsizing the Channel Length of Vertical Organic Electrochemical Transistors
(American Chemical Society, 2023-05-22) Brodský, Jan; Gablech, Imrich; Migliaccio, Ludovico; Havlíček, Marek; Donahue, Mary; Glowacki, Eric Daniel
Organic electrochemical transistors (OECTs) are promising building blocks for bioelectronic devices such as While the majority of OECTs use simple planar geometry, there is interest in exploring how these devices operate with much shorter channels on the submicron scale. Here, we show a practical route toward the minimization of the channel length of the transistor using traditional photolithography, enabling large-scale utilization. We describe the fabrication of such transistors using two types of conducting polymers. First, commercial solution-processed poly(dioxyethylenethiophene):poly(styrene sulfonate), PEDOT:PSS. Next, we also exploit the short channel length to support easy in situ electropolymerization of poly(dioxyethylenethiophene):tetrabutyl ammonium hexafluorophosphate, PEDOT:PF6. Both variants show different promising features, leading the way in terms of transconductance (gm), with the measured peak gm up to 68 mS for relatively thin (280 nm) channel layers on devices with the channel length of 350 nm and with widths of 50, 100, and 200 m. This result suggests that the use of electropolymerized semiconductors, which can be easily customized, is viable with vertical geometry, as uniform and thin layers can be created. Spin-coated PEDOT:PSS lags behind with the lower values of gm; however, it excels in terms of the speed of the device and also has a comparably lower off current (300 nA), leading to unusually high on/off ratio, with values up to 8.6 × 104. Our approach to vertical gap devices is simple, scalable, and can be extended to other applications where small electrochemical channels are desired.
Microfluidic Technology for Clinical Applications of Exosomes
(MDPI, 2019-06-12) Iliescu, Florina Silvia; Vrtačnik, Danilo; Neužil, Pavel; Iliescu, Ciprian
Exosomes, a type of nanovesicle, are distinct cellular entities specifically capable of carrying various cargos between cells. It has been hypothesized that exosomes, as an enriched source of biomolecules, may serve as biomarkers for various diseases. This review introduces general aspects of exosomes, presents the challenges in exosome research, discusses the potential of exosomes as biomarkers, and describes the contribution of microfluidic technology to enable their isolation and analysis for diagnostic and disease monitoring. Additionally, clinical applications of exosomes for diagnostic purposes are also summarized.

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