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Optical Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
Sun et al. (2006) reported the synthesis of a prototype ratiometric pH NS. It contains two dyes: a pH-sensitive fluorescent dye and a pH-insensitive reference dye. The dyes are embedded in a polymer matrix, consisting of porous, highly cross-linked polyacrylamide (–CH2CHCONH2–). Microemulsion polymerization was used for synthesis of particles with diameters ~20–30 nm. To facilitate the insertion of NSs, protoplasts (plant cells without cell wall) of BY2 (Bright yellow-2) tobacco (the most popular and widely used cell line in plant research) were used as the first model system, and the NS particles were inserted into living protoplasts by gene gun bombardment. Confocal laser scanning microscopy (a tool for obtaining high-resolution images with depth selectivity and 3D reconstructions by acquiring in-focus images from selected depths, a process known as optical sectioning) was used to visualize the fluorescence responses. Responses received from the pH-sensitive dye and the reference dye permitted intracellular pH measurements by fluorescence ratio imaging microscopy. In this method, two different excitation wavelengths are used and the emitted light levels compared.
Literature review
Published in Samayita Chakraborty, Biovalorisation of liquid and gaseous effluents of oil refinery and petrochemical industry, 2021
The pH plays an important role in alcohol production. When acetic acid is released outside the cell, being a weak lipophilic acid it permeates inside the cell creating a low pH condition (Abubackar et al., 2012). Permeation occurs due to low molecular weight of the acids. A low extracellular pH would further impose a stress on the cell leading to the switching from acetogenesis to solventogenesis. Hence, the intracellular pH is increased for resuming the regular cell metabolism (Abubackar et al., 2012). However, a very low pH (below 4) would completely inhibit the cell activity. Recently, production of ethanol has been found to be favored at low fermentation pH in mixed cultures, but it stops production of longer chain alcohols like hexanol (Ganigué et al., 2016). Altering the pH throughout the fermentation of Clostridium autoethanogenum (Abubackar et al., 2016) has been found to improve the alcohol productivity. Production of acids at higher pH of 6.2 and conversion of these acids to alcohols have also been observed after changing the pH to 4.9 consecutively by pure cultures like Clostridium carboxidivorans (Fernández-Naveira et al., 2017a).
DFT study on Fe and N decorated graphene as the drug delivery system for β-lapachone anticancer drug
Published in Molecular Physics, 2022
The extracellular pH of normal tissues and blood pH is kept constant at pH 7.4 and their intracellular pH is stable at 7.2 [37]. Tumor pH is lower than normal tissues. The tumor pH was determined by needle microelectrodes show an average pH value of 7.0 with a range between 5.7 and 7.8 [38,39]. Based on the pH around cancerous cells being lower than normal cells, β-lap release to the cancerous cells upon protonation was proposed [40]. Here, we theoretically demonstrated the adsorption for protonated β-lap on Fe-N-Graphene is different from non-protonated β-lap. In Figure 5, the adsorption structures and the differential charge density distribution for adsorbed protonated β-lap were both investigated. For one hydrogen is added to the β-lap molecule, we obtained two kinds of adsorption of single-protonated β-lap named O2@Fe&(H-O3) and O3@Fe&(H-O2) shown in Figure 5(a,b), respectively.
Low cost nutrient-rich oil palm trunk bagasse hydrolysate for bio-succinic acid production by Actinobacillus succinogenes
Published in Preparative Biochemistry & Biotechnology, 2022
Nurul Adela Bukhari, Soh Kheang Loh, Abdullah Amru Indera Luthfi, Peer Mohamed Abdul, Jamaliah Md Jahim
Additional growth requirements e.g., mineral components such as potassium (K), sodium (Na) and phosphate salts should be examined in order to achieve optimal osmotic balance for microbial growth. Na is involved in forming transmembrane pH gradient, intracellular pH regulation, nutrient uptake and cell motility.[29] Magnesium (Mg) also plays a critical role in maintaining cellular metabolism, and thus is regarded as an important cofactor for PEPCK/PEPC, i.e., the key enzyme in bio-SA synthesis.[30] The promising findings from this study proved that the fermentation medium in use, OPT bagasse hydrolysate, contained sufficient minerals for bioprocessing. We used the whole slurry of the oxalic acid-pretreated substrate, which contained sodium salts originated from NaOH applied during the neutralization step. In this case, it was totally unnecessary to dose with Na supplement. The same applied even more so when a minimal 5 g/L of YE in the hydrolysate could already reach optimal bio-SA production. Besides, OPT biomass also contains inorganic nutrient/metal elements, i.e., K, Mg, Al, Fe, and traces of Cu, Zn, Cr, Se and Mn, in considerably high amounts which are essential to support many biological functions.[31] It can be concluded that OPT bagasse hydrolysate has sufficient minerals for bio-SA fermentation and therefore mineral supplementation is entirely avoidable. The consolidation of these findings will deliver tremendous cost savings in processing OPT bagasse hydrolysate into bio-SA.
Second-generation ethanol production by separate hydrolysis and fermentation from sugarcane bagasse with cellulose hydrolysis using a customized enzyme cocktail
Published in Biofuels, 2021
Johanna Méndez, Douglas de França Passos, Daiana Wischral, Luiz Felipe Modesto, Nei Pereira
Acetic acid is usually generated from the acetyl groups that are present in the hemicellulose structure, at a pH that favors alcoholic fermentation (between 5 and 6). In its undissociated form, acetic acid is able to diffuse through the cell’s cytoplasm, where, once dissociated, it promotes a reduction in the intracellular pH level. This situation increases the energetic demands of the cell, and might impair nutrient transportation through the membrane and inhibit the action of several enzymes in the glycolytic pathway [13,40,41].