Concentration Of Zn2 Research Articles

Synthesis and physicochemical characterization of zinc-lactoferrin complexes

One trend of the modern world is the search for new biologically active substances based on renewable resources. Milk proteins can be a solution for such purposes as they have been known for a long time as compounds that can be used for the manufacturing of multiple food and non-food products. Thus, the goal of the work was to investigate the parameters of Zn-bovine lactoferrin (bLTF) interactions, which enables the synthesis of Zn-rich protein complexes. Zinc-bLTF complexes can be used as food additives or wound-healing agents. Methodology of the study included bLTF characterization by sodium dodecyl sulfate-PAGE, MALDI-TOF, and MALDI-TOF/TOF mass spectrometry as well Zn-bLTF interactions by attenuated total reflection-Fourier-transform infrared, Raman spectroscopy, scanning and transmission microscopy, and zeta potential measurements. The obtained results revealed that the factors that affect Zn-bLTF interactions most significantly were found to be pH and ionic strength of the solution and, in particular, the concentration of Zn2+. These findings imply that these factors should be considered when aiming at the synthesis of Zn-bLTF metallocomplexes.

Improved luminescence performance of Yb3+-Er3+-Zn2+: Y2O3 phosphor and its application to solar cells

Upconversion materials (UC) can convert low-energy photons into visible light and, therefore, can be incorporated in solar cells to increase the absorption of visible light. This study synthesized UC nanophosphors Yb3+, Er3+: Y2O3 and Yb3+, Er3+, Zn2+: Y2O3 by a simple co-precipitation method for application in dye-sensitized solar cells (DSSCs). The impact of the enhancement in the concentration of Zn2+ on the photoluminescence (PL) and color point of the synthesized nanophosphors was also investigated. The synthesized nanophosphors emitted intense red and weaker green emissions upon excitation at 980 nm. The incorporation of Zn2+ to the Yb3+, Er3+: Y2O3 nanophosphors leads to color tunability in the red and yellow regions. Furthermore, the synthesized nanophosphors were incorporated into the DSSC photoanode to form a TiO2-UC-based DSSC for converting near-infrared (NIR) into visible light. We observed that the TiO2-UC-based DSSC showed an enhancement ratio in current density and power conversion efficiency of 17.4% and 16.6%, respectively, compared to the bare TiO2-based DSSC. These results reveal that UC-based Yb3+, Er3+, Zn2+: Y2O3 nanophosphors are useful in improving the efficiency of DSSCs and in color tunability applications.

A Schiff-based AIE fluorescent probe for Zn2+ detection and its application as “fluorescence paper-based indicator”

A Schiff-based aggregation induced emission (AIE) fluorescent probe with excited intramolecular proton transfer (ESIPT) mechanism was synthesized by grafting 2-hydrazinobenzothiazole onto 2,6-diformyl-4-methylphenol. The probe recognizes Zn2+ selectively and sensitively, accompanied by a significant fluorescence emission increasement change from light yellow-green to strong green. Additionally, a stabilization time of at least 30 min was kept in the recognition process. Besides, a linear relationship was observed between the concentration of Zn2+ and the fluorescence intensity at 525 nm (0.05–10 µM). And thus, the probe can detect Zn2+ quantitatively in aqueous solution with a low detection limit of 1.9 × 10-8 M. Based on the AIE property and the selective recognition of Zn2+, SCH was strategically loaded on the filter paper to develop a novel paper-based indicator for on-site and high-efficiency detection of Zn2+. The results showed that the paper-based indicator could be conveniently applied to the visual inspection of Zn2+ as expected and SCH in the paper-based indicators fortunately exhibited a better stability. Furthermore, our comprehensive application evaluations have confirmed that SCH was capable of detecting Zn2+ in real water samples and imaging Zn2+ in living cells roundly.

Antibacterial effects and physical properties of a glass ionomer cement containing BioUnion filler with acidity-induced ability to release zinc ion.

BioUnion filler is a bioactive glass particle that releases Zn2+ in an acidic environment. In this study, the ion release, antibacterial, and physical properties of a glass ionomer cement (GIC) incorporating BioUnion filler (CA) were assessed in vitro. The concentration of Zn2+ released from CA into acetic acid was higher than that released into water and its minimum inhibitory concentrations against six oral bacterial species. Moreover, the concentration of Zn2+-release was maintained during all the seven times it was exposed to acetic acid. Compared to a conventional cement and resin composite, CA significantly inhibited the growth of oral bacteria and hindered their adhesion on the material surface. Thus, our study outcomes show that the release of Zn2+ from CA in the acidic environment does not affect its compressive strength.

Selective aerobic oxidation of benzyl alcohol on inexpensive and reusable ZnO/MnCO3 catalyst

The selective synthesis of benzaldehyde (B) by oxidation of benzyl alcohol (BA) was studied at 373 K using ZnO-MnCO3 catalysts, O2 as oxidant and mild reaction conditions. An inexpensive commercial MnCO3 sample was impregnated with aqueous solutions containing different concentration of Zn2+ cations to obtain a series of ZnO-MnCO3 catalysts with 1.0–22.6 wt% Zn. Catalysts were characterized by N2 physisorption, atomic absorption spectrometry, X-ray diffraction and X-ray photoelectron spectroscopy techniques. Benzaldehyde was selectively formed during liquid phase oxidation of benzyl alcohol but the catalytic performance of the ZnO-MnCO3 materials depended on Zn loading. The maximum initial reaction rate value was measured on the most promising catalyst (15.4 wt% Zn) and a maximum of 88% benzaldehyde yield was achieved on this catalyst after 6 h of reaction using toluene as solvent. The catalytic activity of the ZnO-MnCO3 materials could be assigned to a synergistic contribution of Zn and Mn species. While the main role of ZnO would be related to its capacity to chemisorb the alcohol, the role of highly oxidized Mn surface species (mainly Mn4+) generated during catalyst preparation, is to participate in de redox mechanism involved in benzyl alcohol oxidation toward benzaldehyde. The effect of chemical nature of polar and apolar aprotic solvents was investigated during the aerobic oxidation over 15.4ZnMn. Apolar solvents, in which the oxygen solubility is higher than in the benzyl alcohol, are more suitable for the reaction. An optimum in solvent basicity requirements (hydrogen-bond-acceptance) in order to optimize the catalyst activity was found. The regeneration and reuse of the most promising catalyst were also investigated. A mild thermal treatment at 493 K in flowing air was enough to fully recover the activity of the 15.4ZnO-MnCO3 catalyst.

A study of wastewater purification from Zn2 + ions by nanosorbent, obtained by electroerosion dispersion

Сurrent state and efficiency of existing sorbtion methods of industrial wastewater treatment are considered. The influence of important parameters for sorbtion process - ratio of metal ion and nanosorbent concentrations in solution, as well as the method of sorbent addition into wastewater on degree of its purification was studied. The most effective results of water purification were achieved with usage of freshly obtained powder of electroerosive dispersion (EED) of iron in water in the form of a suspension at ratio of the concentration of Zn2+ ions and nanosorbent powder 1:10. It Under such conditions a high degree of removing as 98% is determined, and obtained purified solution meets the standards of rising water at galvanic facilities, regarding of Zn2+ content.

TPEN attenuates amyloid-\u03b225\u201335-induced neuronal damage with changes in the electrophysiological properties of voltage-gated sodium and potassium channels

To understand the role of intracellular zinc ion (Zn2+) dysregulation in mediating age-related neurodegenerative changes, particularly neurotoxicity resulting from the generation of excessive neurotoxic amyloid-β (Aβ) peptides, this study aimed to investigate whether N, N, N′, N′-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN), a Zn2+-specific chelator, could attenuate Aβ25–35-induced neurotoxicity and the underlying electrophysiological mechanism. We used the 3-(4, 5-dimethyl-thiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay to measure the viability of hippocampal neurons and performed single-cell confocal imaging to detect the concentration of Zn2+ in these neurons. Furthermore, we used the whole-cell patch-clamp technique to detect the evoked repetitive action potential (APs), the voltage-gated sodium and potassium (K+) channels of primary hippocampal neurons. The analysis showed that TPEN attenuated Aβ25–35-induced neuronal death, reversed the Aβ25–35-induced increase in intracellular Zn2+ concentration and the frequency of APs, inhibited the increase in the maximum current density of voltage-activated sodium channel currents induced by Aβ25–35, relieved the Aβ25–35-induced decrease in the peak amplitude of transient outward K+ currents (IA) and outward-delayed rectifier K+ currents (IDR) at different membrane potentials, and suppressed the steady-state activation and inactivation curves of IA shifted toward the hyperpolarization direction caused by Aβ25–35. These results suggest that Aβ25–35-induced neuronal damage correlated with Zn2+ dysregulation mediated the electrophysiological changes in the voltage-gated sodium and K+ channels. Moreover, Zn2+-specific chelator-TPEN attenuated Aβ25–35-induced neuronal damage by recovering the intracellular Zn2+ concentration.

In-vitro evaluation and antibacterial activity of ZnO nanoparticles deposited on hydroxyapatite tablets by RF magnetron sputtering

RF magnetron sputtering was successfully applied in this study to deposit ZnO nanoparticles on hydroxyapatite tablets. Field emission scanning electron microscopy (FE-SEM) images showed the growth of ZnO nanoparticles with a grain size of ∼ 20 nm. Sedimentation occurred on the surface of samples after their immersion in simulated body fluid. Energy dispersive spectroscopy (EDS) analysis, confirmed the presence of Ca, P, Zn, and O elements, while MAP analysis indicated the uniform distribution of hydroxyapatite and ZnO elements. Atomic force microscopy (AFM) revealed lower surface roughness in the coated samples as compared to their uncoated counterparts. The root means square of roughness decreased with the ZnO coating. X-ray diffraction (XRD) results suggest the presence of the ZnO and hydroxyapatite phases. Antibacterial assay of ZnO-coated and uncoated tablets indicated the higher bioactivity of ZnO-coated tablets against E. coli. The atomic absorption spectrophotometry (AAS) and flame photometer results showed the release of Zn2+ and Ca2+ ions from the samples, respectively. During 14 days of immersion in simulated body fluid (SBF), Due to corrosion and destruction of the surface of the samples the Ca2+ concentration of ZnO-coated and uncoated samples, as well as the concentration of Zn2+ ions of ZnO-coated samples exhibited an increase.

Selective detection of Zn2+ and Cd2+ ions in water using a host-guest complex between chromone and Q[7

In this paper, the host-guest interaction of cucurbit[7]uril (Q[7]) and chromone (CMO) has been developed as a fluorescent probe for the highly selective detection of Zn2+ and Cd2+ in water based on a chelation-enhanced fluorescence (CHEF) mechanism. There was a good linear relationship between the fluorescence intensity of the CMO@Q[7] probe and the concentration of Zn2+ or Cd2+ in the range of 0–3.0 × 10–5 mol/L and the detection limit for Zn2+ and Cd2+ was found to be 2.03 × 10–6 mol/L and 1.89 × 10–6 mol/L, respectively. The X-ray crystal structure indicated that different coordination fashions were triggered by Zn2+ and Cd2+ in the CMO@Q[7] complexes, respectively. However, both metal ions coordinated with the carbonyl oxygen of CMO, which was encapsulated in the cavity of Q[7], thus leading to the enhancement of recognition fluorescence emission of CMO.

Self-assembly nuclei with a preferred orientation at the extended hydrophobic surface toward textured growth of ZnO nanorods in aqueous chemical bath deposition

Textured growth of ZnO nanorods with no restriction of the substrate material is beneficial to their applications. The approaches to grow ZnO nanorods with texture are based on preparing suitable surface structure on the growth substrate, e.g. using a crystalline substrate with a specific surface structures or pre-depositing seed layers by high-temperature annealing of precursors. In the aqueous nutrient solution of the chemical bath deposition (CBD) process for ZnO growth, the concentration of Zn2+ ions at the extended hydrophobic surface is sufficiently high for forming self-assembly nuclei with a preferred orientation, resulting in the subsequent textured growth of ZnO nanorods. In this research, the hydrophobic surface is prepared by modifying Si surface with a self-assembly octadecyltrimethoxysilane (OTMS) monolayer. The formation mechanism of the nuclei on this hydrophobic surface for the textured growth of ZnO nanorods is investigated. It is shown that the nuclei form at the beginning of the CBD process and later transform into the Wurtzite structure to seed ZnO growth. An alternative approach to prepare seed layers is therefore involved in the aqueous CBD process, which is applicable to a range of hydrophobic substrates for textured growth of ZnO nanorods.

Nanoscale Zeolitic Imidazolate Framework-8 Activator of Canonical MAPK Signaling for Bone Repair.

Zeolitic imidazolate framework-8 (ZIF-8) is an important type of metal organic framework and has found numerous applications in the biomedical field. Our previous studies have demonstrated that nano ZIF-8-based titanium implants could promote osseointegration; however, its osteogenic capacity and the related mechanisms in bone regeneration have not been fully clarified. Presented here is a nanoscale ZIF-8 that could drive rat bone mesenchymal stem cell (rBMSC) differentiation into osteoblasts both in vitro and in vivo, and interestingly, nano ZIF-8 exhibited a better osteogenic effect compared with ionic conditions of Zn at the same concentration of Zn2+. Moreover, the cellular uptake mechanisms of the nanoparticles were thoroughly clarified. Specifically, nano ZIF-8 could enter the rBMSC cytoplasm probably via caveolae-mediated endocytosis and macropinocytosis. The intracellular and extracellular Zn2+ released from nano ZIF-8 and the receptors involved in the endocytosis may play a role in inducing activation of key osteogenic pathways. Furthermore, through transcriptome sequencing, multiple osteogenic pathways were found to be upregulated, among which nano ZIF-8 primarily phosphorylated ERK, thus activating the canonical mitogen-activated protein kinase pathway and promoting the osteogenesis of rBMSCs. Taken together, this study helps to elucidate the mechanism by which nano ZIF-8 regulates osteogenesis and suggests it to be a potential biomaterial for constructing multifunctional composites in bone tissue engineering.

Evaluation of B-ZnO on photocatalytic inactivation of Escherichia coli and Enterococcus sp

In this study the photocatalytic inactivation of Escherichia coli (E. coli) and Enterococcus sp. wild strains was carried out using as photocatalyst boron-doped ZnO (B-ZnO). The photocatalytic performance of this material was compared with two commercial catalysts: ZnO and TiO2. Furthermore, the control processes of solar disinfection (SODIS) and stirring were evaluated. The performance of the catalysts was evaluated under darkness and solar simulated irradiation. Logarithmic units of inactivation and concentration of Zn2+ release during the experiments were determined. The photocatalytic inactivation of the strains was adjusted to a log-linear shoulder or tail kinetic model. To maximize the kinetic constant and determine the catalyst with the best photocatalytic performance, a desirability function was applied. Under darkness, stirring and TiO2 in suspension did no present effect in the population of both bacteria. A reduction of 1-log unit of E. coli was observed in the processes with ZnO and B-ZnO on darkness. However, Enterococcus sp. only was inactivated in darkness using B-ZnO, reaching 1.5-log. The increase of the antimicrobial effect of B-ZnO was attributed to Zn2+ release and the formation of acid sites promoted by B3+ ions in the B-ZnO catalyst. Under solar simulated irradiation, E. coli and Enterococcus sp. reached 6-log and 3-log respectively during 180 min of exposure without catalyst. The photocatalytic inactivation of E. coli was negligible using TiO2 catalyst, while heterogeneous photocatalysis using ZnO and B-ZnO materials reached 6-log during 30 min and 60 min of lighting, respectively. The photocatalytic inactivation of E. coli using ZnO exhibited higher kinetic constant value (1.12 min−1) compared to that obtained with doped B-ZnO (0.23 min−1). In the case of the photocatalytic inactivation of Enterococcus sp., 3-log in 180 min was reached using B-ZnO (0.22 min−1) while 1-log was attained using ZnO (0.02 min−1) and TiO2 (0.04 min−1). From desirability function, the maximization of the kinetic constants of inactivation of E. coli and Enterococcus sp. allowed selecting the B-ZnO as the best material due to its enhanced photocatalytic antimicrobial activity against both strains.

Effects of Humic Acid and Natural Sunlight Irradiation on the Behaviour of Zinc Oxide Nanoparticles in the Aqueous Environment

The unique properties of ZnO nanoparticles have attracted scientists’ interest to produce on a large-scale. Household items, cosmetics, consumer products, and electric sensors are some products that utilize these ZnO nanomaterials. Eventually, ZnO nanoparticles will be released into the environment in various ways. Once released, ZnO nanoparticles would dissociate into Zn2+ ions, which are toxic to aquatic organisms. The presence of humic acid and exposure to sunlight could affect the dissolution of ZnO nanoparticles. Two sizes of commercial ZnO nanoparticles (< 50 nm and < 100 nm) were chosen to study the influence of humic acid and sunlight on the dissolution. In the presence of humic acid, the dissolution of both sizes is higher, with 67 % and 39 % Zn2+ dissolved for < 50 nm and < 100 nm, respectively. The concentration of Zn2+ ions seems to be consistent or stable when exposed to sunlight. However, the humic acid enhanced the release of Zn2+ ions. Langmuir isotherm model best fitted for the humic acid's sorption onto the ZnO nanoparticles with the process been favorable.

Transport of zinc ions in the hyporheic zone: Experiments and simulations

Large amounts of toxic metals are discharged into rivers and lakes, but little is known about the factors that drive the adsorption and transformation of these metals in the hyporheic zone and the exchange flux across the sediment-water interface. To better understand transport and transformation of metal ions in the hyporheic zone, flume experiments and numerical simulations were performed in a streambed with periodic bedforms using zinc ions. Compared to non-adsorbing contaminant, the results show that adsorption leads to a more rapid decrease in the concentration of Zn2+ in the overlying water, and a lower final concentration is reached. The mass of adsorbed ions is several times higher than that of free ions in the bedform's water phase. Indeed, metal adsorption is in the shallow layer of the streambed. Although this prevents heavy metal groundwater contamination, the same cannot be said of shallow layer of the hyporheic zone. Knowledge of the migration and transformation of metal ions in the hyporheic zone provides insights pertinent to the restoration of polluted rivers.

Characterization of Radiation-Resistant Yeast Isolated from Radiation-Polluted Areas and Its Potential Application in Bioremediation

Twenty-four yeast isolates were obtained from radiation-polluted areas soils samples exposed to 60Co-γ radiation at a dose of 10 kGy and identified as members of the genus Cryptococcus based on morphological and LSU rDNA D1/D2 domain sequence analysis. Further phylogenetic analysis showed that the isolates were clustered into 4 branches. The investigation of these yeast isolates revealed D10 values for γ radiation of 5 (M2), 5 (M38), 6 (M22) and 7 kGy (M5) and a 4 × 10–3% survival rate at a UV dosage of 200 J/m2. Furthermore, the tolerance of M5 towards Zn2+ was as high as 1.700 mg/L. The isolate M5 was selected for further study, including the distribution of heavy metals within the cells by subcellular fractionation, expression of relevant genes involved in heavy metal resistance by qRT-PCR, and the removal rate by flame atomic absorption spectrometry (FAAS). The results revealed that almost 72.9% of the Zn2+ was absorbed by the cells and deposited mainly in the membrane fraction. Compared to normal conditions, all of the genes in M5 strain related to transport and regulation showed greater than 10.4-fold increases of expression levels upon exposure to heavy metal stress. In the presence of culture medium, a total of 86.5% of the initial concentration of Zn2+ was removed by the M5 strain exhibiting high removal efficiency and providing a potential of radiation-resistant platform strain for the bioremediation of heavy metals in polluted environments in the near future.

Sintering mechanism and properties of MgAl2O4–CaAl12O19 composites with ZnO addition

MgAl2O4–CaAl12O19 (MA-CA6) composites were prepared using Al2O3, MgO and CaCO3 powders as the raw materials by solid-state reaction sintering at 1200–1600 ℃. The effects of ZnO addition on the physical and mechanical properties, microstructure, and phase composition were investigated. ZnO additive can significantly increase the amount of MA due to the formation of the (Mg1-xZnx)Al2O4 solid solution, which greatly improves the densification and the flexural strength of the composites after sintering at 1600 ℃. Flexural strength reaches a maximum of 192.1 MPa and apparent porosity is 8.5 % when 2 wt% of ZnO is added. This is resulted by the close bonding between MA and CA6 grains. However, further increasing the ZnO content results in a slight decrease in the strength of the composites due to the weakening of the plate-like CA6 bridging effect and the concentration of Zn2+ at the MA grain boundary.

Study of La(Fe, Zn)O3 on the structural properties prepared by sol-gel method

Partial substitution of other metallic ions at La and/or Fe sites of LaFeO3 had been applied to modify the structural properties and for enhancing the properties of its material. In this present work, we prepared LaFeO3 by replacing a portion of Fe3+ with Zn2+ with x = 0.03; 0.05; and 0.07 to study the effect on the structural which prepared by sol-gel method. The samples were identified by X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Fourier Transform Infrared (FTIR) spectra, Raman spectroscopy, and Ultraviolet-Visible Diffuse Reflectance spectroscopy (UV-Vis DRS). XRD pattern showed all of the samples formed in single crystal and are having an orthorhombic structure with space group Pbnm. The lattice parameters were found to be slightly increased with the increase of Zn concentration. The result of FTIR spectra and Raman spectra also show further information about the formation of LaFeO3 with the distortion due to the replacement of Zn2+ into Fe3+. The absorbance and reflectance of samples are measured using UV-Vis DRS and the energy band gap of LaFe1-x Zn x O3 ( x = 0.03; 0.05; and 0.07) are determined by Tauc plot using Kubelka-Munk function and was found the energy band gap slightly decreased as the concentration of Zn2+ increased.

SCREEN PRINTED ELECTRODE OF CARBON NANOTUBES MODIFIED WITH GOLD NANOPARTICLES FOR SIMULTANEOUS DETERMINATION OF ZINC, LEAD AND COPPER

Differential pulse anodic stripping voltammetry, method used for simultaneous determination of zinc, copper and lead with screen printed electrode of carbon nanotubes modified with gold nanoparticles was investigated. The results indicate that a simultaneous identification and quantification of zinc, lead and copper is possible at -0.6 V, -0.26 V and 0.16 V respectively. The maximum current was linearly dependent on the concentration of Zn2+, Pb2+ and Cu2+, thus allowing the construction of analytical curves, being: -Ip (A) = 0.08 + 0.214 [Zn2+ (g L-1)] in a range of 9.9 to 120 mg L-1 with an R2 = 0.993; -Ip (A) = -1.06 + 0.240 [Pb2+ (mg L-1)] in a range of 9.9 to 120 mg L-1 with an R2 = 0.998; -Ip (A) = -10.93 + 15.16 [Cu2+ (mg L-1)] in a range of 0.99 to 12 mg L-1 with an R2 = 0.998. The limits of detection and quantification were estimated between 1.0 - 3.5 mg L-1 for Zn2+, 1.5 - 5.0 mg L-1 for Pb2+ and 0.1 - 0.33 mg L-1 for Cu2+. An integral, selective and reliable system for simultaneous determination of heavy metals was achieved, which may have applications in field monitoring for environmental use and public health.

Reduction of charge variants by CHO cell culture process optimization.

Over the past decade, global interest in the development of therapeutic monoclonal antibodies (mAbs) has risen rapidly. As therapeutic agents, antibodies have shown marked efficacy in combatting a range of cancers and immune diseases with high target specificity and low toxicity (Carla Lucia et al. in PLoS ONE 6:e24071, 2011; Donaghy in MAbs 8:659-671, 2016; Nasiri et al. in J Cell Physiol 9:6441-6457, 2018; Teo et al. in Cancer Immunol Immunother 61:2295-2309, 2012). Recent advances in cell culture technology, such as high-throughput clone screening, have facilitated antibody production at concentrations exceeding 10 g/L (Chen et al. in BMC Immunol 19:35, 2018; Huang et al. in Biotechnol Prog 26:1400-1410, 2010; Lu et al. in Biotechnol Bioeng 110:191-205, 2013; Singh et al. in Biotechnol Bioeng 113:698-716, 2016). As titers have improved, the industry has begun to focus on the adjustment of target antibody quality profiles to improve efficacy. Cell lines, culture media, and culture conditions impact protein quality (Van Beers and Bardor in Biotechnol J 7:1473-1484, 2012). Optimization of critical quality attributes (CQAs), such as charge variants, can be achieved through bioprocess development and is the preferred approach as changes to the cell line or growth media used is considered unfavorable by regulatory bodies (Gawlitzek et al. in Biotechnol Bioeng 103:1164-1175, 2009; Jordan et al. in Cytotechnology 65:31-40, 2013; Pan et al. in Cytotechnology 69:39-56, 2016). In this study, the effect of process control and ion supplementation on charge variants of mAbs produced by Chinese hamster ovary (CHO) cells was investigated. Results of this study demonstrated that the concentration of Zn2+, duration of culturing, and temperature affect charge variants of a given mAb. Under the optimum conditions of 3L bioreactors, the most significant was that Zn2 + and temperature shift could further improve the quality of antibody. The main peak increased by 12%, and the acid peak decreased by 16%. At the same time, there was no significant loss of titer. This study provided supporting evidence for methods to improve charge variants arising during mAb production.

Design and Synthesis of a Ratiometric Photoacoustic Probe for In Situ Imaging of Zinc Ions in Deep Tissue In Vivo.

As a noninvasive deep-tissue imaging technique, photoacoustic (PA) imaging has great application potential in biomedicine and molecular diagnosis. The zinc ion (Zn2+), which is a necessary metal ion in the human body, plays a very important role in the regulation of gene transcription and metalloenzyme function. The imbalance of Zn2+ homeostasis is also associated with a variety of neurological diseases. Therefore, it is critically important to accurately image the steady-state changes of Zn2+ in vivo. However, no PA imaging method is currently available for Zn2+. To this end, we designed and synthesized the first PA probe of Zn2+, namely, CR-1 for in situ ratiometric imaging of Zn2+ in deep tissue in vivo. The CR-1molecule, combined with Zn2+, weakened the conjugation system of the π-electron in the CR-1 molecule, which resulted in the blue shift of its absorption peak from 710 nm to 532 nm. The PA signal intensity decreased at 710 nm and increased at 532 nm, and the ratiometric PA signal at these two wavelengths (PA532/PA710) showed a good linear relationship with the concentration of Zn2+ in the range of 0-50 μM, with a detection limit as low as 170 nM. Furthermore, this probe exhibits extremely fast responsiveness, is highly selective, and has excellent biocompatibility. We have used the developed PA probe for the ratiometric PA imaging of Zn2+ in the thigh tissue of mice, and we still can accurately image Zn2+ after covering chicken breast tissue on the surface of mice thigh. In light of these outstanding features, the developed PA probe has high potential for imaging Zn2+ in deep tissues; thus, it will open up new avenues for the study of the complex biochemical processes involving Zn2+ in vivo.