China
Africa
Explore chapters and articles related to this topic
Assay of Antibiotics in Mammalian Cell Culture
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
The inhibition of dye-reducing activity of mammalian cells suspended in agar has been applied to the preliminary screening of cytotoxic substances by a number of investigators [14–20]. All these methods rely on the inhibition of dehydrogenase activity of cells visually detected by the lack of reduction of a redox indicator. The assay method that follows was developed for use with suspension-grown cultures of P388 and L1210 cells and differs from other diffusion assays in one or more respects, such as cell line, nutrient media, incubation conditions, or redox agent. The method was modified further through the use of square plastic plates (23×23 cm), which provided agar layers of more uniform thickness and also permitted plate inversion during the incubation period, resulting in more accurate and better defined zones of activity. Although this method has not been described in detail previously, its use as a prescreen for the detection of antitumor agents in fermentation products has been reported [21]. This method has proven to be particularly useful in the isolation and purification of cytotoxic substances from mixtures of unidentified antimicrobial products. Both agar disks saturated with chemical extracts and thin-layer chromatograms (TLC) may be utilized in this assay system. Although growth inhibition assays are more sensitive, dehydrogenase inhibition in agar plates has distinct advantages, namely, ease of operation, rapidity, large amounts of test substances are not required, and suitability for bioautography.
Molecular Diagnostics of Chronic Myeloid Leukemia: Precision Medicine via Gold Nanoparticles
Published in Il-Jin Kim, Companion Diagnostics (CDx) in Precision Medicine, 2019
Raquel Vinhas, Alexandra R. Fernandes, Pedro V. Baptista
Electrochemical biosensing based on nucleic acid hybridization has also attracted considerable attention since it provides a sensitive, accurate, rapid, portable, and cost-effective platform for numerous fields including medical diagnostics. The working principle of this type of biosensors relies on measuring the conductivity resulting from the noncovalent interactions between the hybrid nanocomposite and the DNA probe, which can be used to monitor the hybridization to the target molecule.51 Li et al. developed an electrochemical genosensor based on gold and CeO2 nanoparticles for the detection of BCR–ABL1 fusion gene in CML. This simple DNA biosensor employed methylene blue as an external redox indicator and the design of the following nanocomposite: in situ synthesis of AuNPs at the surface of multi-walled carbon nanotubes (MWCNTs), CeO2 nanoparticles, and chitosan, immobilized in a glassy carbon electrode (GCE). The prepared membrane integrated the strong adsorption ability of CeO2 to the DNA probes, the high conductivity of AuNPs, and the large surface area and excellent electron-transfer ability of MWCNTs. The proposed method was tested using synthetic oligonucleotides and PCR products, offering good selectivity, stability, reproducibility, and simplicity.50 Despite all these advantages, this system has not yet applied to clinical samples or was not provided by the authors.
Nucleic acid-based electrochemical biosensors for rapid clinical diagnosis: advances, challenges, and opportunities
Published in Critical Reviews in Clinical Laboratory Sciences, 2022
Abu Hashem, M. A. Motalib Hossain, Ab Rahman Marlinda, Mohammad Al Mamun, Suresh Sagadevan, Zohreh Shahnavaz, Khanom Simarani, Mohd Rafie Johan
The EC NA biosensor is based on the attraction of ssDNA for its complementary strand to identify target sequences [50]. The electrode modified with bio-capture NA is placed in the buffer solution containing the target analytes. A hybrid duplex is formed between the bio-capture probe and the target NA at the electrode surface, or its hairpin structure is reformed or released. After hybridization, the electrical properties of the biosensor system are altered, and these changes are measured directly as current/resistance by the signal processor. Redox indicator compounds such as methylene blue are used to increase the signal. Such indicator chemicals are intercalated or electrochemically bound to hybridized molecules, resulting in enhanced electrochemical signals and allowing more sensitive and precise detection. The preparation of effective bio-capture modified electrodes along with the design of specific bio-capture probe sequences are important in developing the EC NA biosensor [31,51].
Interfacial water and its potential role in the function of sericin against biofouling
Published in Biofouling, 2019
Ricardo Pedregal-Cortés, Guillermo Toriz, Ezequiel Delgado, Gerald H. Pollack
Aqueous DCPIP solution (0.1%, w v–1) was used to test the pH gradients induced by the surface of RSS in contact with water. This reversible redox indicator was preferred over the universal pH dye because of its relatively low redox potential, +217 mV (Rao and Hayon 1973) and high sensitivity as a pH indicator. Moreover, this indicator shows distinctive changes in color ranging from translucent to pink and blue (Eröss et al. 1964). A hydrated RSS film was soaked in the DCPIP solution, placed on a glass slide and immediately afterwards 150 μl of the same solution were added and a coverlid placed on top. Images were taken (first at 3 min and then every minute up to 20 min) with an optical microscope using reflected-mode illumination (Amscope stereo microscope with adapted EO HB camera).
Using hydrogen peroxide to prevent antibody disulfide bond reduction during manufacturing process
Published in mAbs, 2018
Cheng Du, Yunping Huang, Ameya Borwankar, Zhijun Tan, Anthony Cura, Joon Chong Yee, Nripen Singh, Richard Ludwig, Michael Borys, Sanchayita Ghose, Nesredin Mussa, Zheng Jian Li
Since the disulfide bond reduction is a redox reaction, it is possible to use redox indicators as a simple, rapid and robust way to replace the DTNB test and to forecast the potential risk of LMW formation during harvest and recovery. A redox indicator undergoes a definite color change at a specific electrode potential in a similar way as pH indicators undergo a color change at a specific pH. To find the appropriate redox indicator, an array of commercially available redox indicators were tested, and several were identified as the best potential candidates that can be used in biologics manufacturing process.