Chromo-Fluorogenic Rhodamine-Based Amphiphilic Probe as a Selective and Sensitive Sensor for Intracellular Cu(I) in Living Cells.

Fluorescent probes are widely studied for metal ion detection because of their multiple favorable properties such as high sensitivity and selectivity, quick response, naked eye detection, and in situ monitoring. However, optical probes that can effectively detect the Cu(I) level in cell interiors are rare due to the difficulty associated with selectively and sensitively detecting this metal ion in a cell environment. Therefore, we designed and synthesized three water-soluble probes (1-3) with a 1,3,5-triazine core decorated by three substituents: a hydrophobic alkyl chain, a hydrophilic maltose, and a rhodamine B hydrazine fluorophore. Among the probes, probe 1, which has an octyl chain and a branched maltose group, was the most effective at sensing Cu+ in aqueous solution. Upon addition of Cu+, this probe showed a dramatic color change from colorless to pink in daylight and displayed an intense yellow fluorescence emission under 365 nm light. The limit of detection and dissociation constant (Kd) of this probe were 20 nM and 1.1 × 10-12 M, respectively, which are the lowest values reported to date. The two metal ion-binding sites and the aggregation-induced emission enhancement effect, endowed by the branched maltose group and the octyl chain, respectively, are responsible for the high sensitivity and selectivity of this probe for Cu+ detection, as demonstrated by 1H NMR, dynamic light scattering, and transmission electron microscopy studies. Furthermore, the probe successfully differentiated the Cu(I) level of cancer cells from that of the normal cells. Thus, the probe holds potential for real-time monitoring of Cu(I) level in biological samples and bioimaging of cancer cells.

The therapeutic efficacy of silver loaded rhenium disulfide nanoparticles as a photothermal agent for cancer eradication.

Cancer is a life-threatening disease when it is diagnosed at a late stage or treatment procedures fail. Inhibiting cancer cells in the tumor environment is a significant challenge for anticancer therapy. The photothermal effects of nanomaterials are being studied as a new cancer treatment. In this work, rhenium disulfide (ReS2) nanosheets were made by liquid exfoliation with gum arabic (GA) and coated with silver nanoparticles (AgNPs) to produce reactive oxygen species that destroy cancer cells. The synthesized AgNP-GA-ReS2 NPs were characterized using UV, DLS, SEM, TEM, and photothermal studies. According to the DLS findings, the NPs were about 216 nm in size and had a zeta potential of 76 mV. The TEM and SEM analyses revealed that the GA-ReS2 formed single-layered nanosheets on which the AgNPs were distributed. The photothermal effects of the AgNP-GA-ReS2 NPs at 50 µg/mL were tested with an 808 nm laser at 1.2 W cm-2, and they reached 55.8 °C after 5 min of laser irradiation. MBA-MB-231 cells were used to test the cytotoxicity of the newly designed AgNP-GA-ReS2 NPs with and without laser irradiation for 5 min. At 50 µg/mL, the AgNP-GA-ReS2 showed cytotoxicity, which was confirmed with calcein and EtBr staining. The DCFH-DA and flow cytometry analyses demonstrated that AgNP-GA-ReS2 nanosheets under NIR irradiation generated ROS with high anticancer activity, in addition to the photothermal effects.

Service Employees' Mindfulness and Job Crafting amid COVID-19: The Roles of Resilience, Organizational Health Climate, and Health-Oriented Leadership.

Due to changes in the work environment resulting from the COVID-19 pandemic, service employees' behavior, that proactively reshapes the content and meaning of work (i.e., job crafting), is increasingly important. We identified mindfulness as a key individual trait contributing to job crafting in the pandemic context. The purpose of our study was to examine the mediating effect of resilience on the relationship between mindfulness and job crafting, and the moderating effects of perceived organizational health climate and health-oriented leadership on the mindfulness-resilience relationship. We administered two-wave online surveys to 301 South Korean service employees after the onset of COVID-19 (January 20, 2020). Data for mindfulness, resilience, perceived organizational health climate, and health-oriented leadership were collected via participants' self-report in March, 2020. One month later (April, 2020), we obtained their self-ratings of job crafting. Results showed that resilience mediated the relationship between mindfulness and job crafting. The positive relationship between these two variables was more pronounced when perceived organizational health climate was high than when it was low. Perceived organizational health climate further moderated the indirect effect of mindfulness on job crafting through resilience.

Multicomponent metal-organic framework nanocomposites for tumor-responsive synergistic therapy.

Targeted tumor therapy through tumor microenvironment (TME)-responsive nanoplatforms is an emerging treatment strategy used to enhance tumor-specificity to selectively kill cancer cells. Here, we introduce a nanosized zeolitic imidazolate framework-8 (ZIF-8) that simultaneously contains natural glucose oxidase (GOx) and Prussian blue nanoparticles (PBNPs) to construct multi-component metal-organic framework nanocomposites (denoted as ZIF@GOx@PBNPs), which possess cascade catalytic activity selectively within the TME. Once reaching a tumor site, GOx and PBNPs inside the nanocomposites are sequentially released and participate in the cascade catalytic reaction. In weak acidic TME, GOx, which effectively catalyzes the oxidation of intratumoral glucose to hydrogen peroxide (H2O2) and gluconic acid, not only initiates starvation therapy by cutting off the nutrition source for cancer cells but also produces the reactant for sequential Fenton reaction for chemodynamic therapy. Meanwhile, PBNPs, which are released from the ZIF-8 framework dissociated by acidified pH due to the produced gluconic acid, convert the generated H2O2 into harmful radicals to melanomas. In this way, the cascade catalytic reactions of ZIF@GOx@PBNPs enhance reactive oxygen species production and cause oxidative damage to DNA in cancer cells, resulting in remarkable inhibition of tumor growth. The tumor specificity is endowed by using the biomolecules overexpressed in TME as a "switch" to initiate the first catalytic reaction by GOx. Given the significant antitumor efficiency both in vitro and in vivo, ZIF@GOx@PBNPs could be applied as a promising therapeutic platform enabling starvation/chemodynamic synergism, high therapeutic efficiency, and minimal side effects.

Ratiometric orange fluorescent and colorimetric highly sensitive imidazolium-bearing naphthoquinolinedione-based probes for CN- sensing in aqueous solutions and bio-samples.

The widespread use of cyanide (CN-) in industry results in contamination of various effluents such as drain, lake, and tap water, an imminent danger to the environment and human health. We prepared naphthoquinolinedione (cyclized; 1-5) and anthracenedione (un-cyclized) probes (6-7) for selective detection of CN-. The addition of CN- to the probe solutions (1-5) resulted in a color change from pale green to orange under 365 nm illumination. The nucleophilic addition of CN- to C2 of the imidazolium ring of the probes is responsible for selective CN- detection. Among all probes, 1 gave the lowest fluorescence-based LOD of 0.13 pM. In contrast, the un-cyclized probes (6 and 7) were substantially inferior to the cyclized counterparts (1 and 2, respectively) for detecting a trace amount of CN-. The notably low LOD displayed by probe 1 was maintained in the detection of CN- in real food samples, human fluids, and human brain cells. This is the first report studying imidazolium-bearing naphthoquinolinedione-based probes for CN- sensing in 100% water.

Gum Arabic-mediated liquid exfoliation of transition metal dichalcogenides as photothermic anti-breast cancer candidates.

Transition metal dichalcogenides (TMDs) have gained considerable attention for a broad range of applications, including cancer therapy. Production of TMD nanosheets using liquid exfoliation provides an inexpensive and facile route to achieve high yields. In this study, we developed TMD nanosheets using gum arabic as an exfoliating and stabilizing agent. Different types of TMDs, including MoS2, WS2, MoSe2, and WSe2 nanosheets, were produced using gum arabic and were characterized physicochemically. The developed gum arabic TMD nanosheets exhibited a remarkable photothermal absorption capacity in the near-infrared (NIR) region (808 nm and 1 W⋅cm-2). The drug doxorubicin was loaded on the gum arabic-MoSe2 nanosheets (Dox-G-MoSe2), and the anticancer activity was evaluated using MDA-MB-231 cells and a water-soluble tetrazolium salt (WST-1) assay, live and dead cell assays, and flow cytometry. Dox-G-MoSe2 significantly inhibited MDA-MB-231 cancer cell proliferation under the illumination of an NIR laser at 808 nm. These results indicate that Dox-G-MoSe2 is a potentially valuable biomaterial for breast cancer therapy.

Daily relationships between job insecurity and emotional labor amid COVID-19: Mediation of ego depletion and moderation of off-job control and work-related smartphone use.

The economic recession in the service sector during the COVID-19 pandemic has jeopardized service employees' job security. While the daily fluctuations of perceived job insecurity may have implications for service employees' emotional labor, the day-to-day relationship between these two variables and their mediating and moderating mechanisms in the pandemic context remain unknown. To fill this gap, our research examined the day-level relationship between job insecurity perceptions, ego depletion, and emotional labor, as well as the moderating effects of overnight off-job control and work-related smartphone use. To assess these relationships, we conducted two daily studies during the COVID-19 pandemic. In study 1 (March-April 2020), 135 service employees responded to morning and evening online surveys for five workdays. In study 2 (June 2022), which administered morning and evening online surveys to 90 flight attendants for five workdays, work-related COVID-19 exposure risk was controlled in the analyses. The results of the two studies demonstrated that on a day when service employees perceived a high level of job insecurity, they felt ego-depleted, which, in turn, was associated with decreased deep acting and increased surface acting. Post hoc findings indicated a significant three-way interaction between off-job control, off-job work-related smartphone use, and daily job insecurity, such that the job insecurity-ego depletion-emotional labor was most pronounced when off-job control was low and off-job work-related smartphone use was high. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Determination of lysophosphatidylcholine using peroxidase-mimic PVP/PtRu nanozyme.

Lysophosphatidylcholine (LPC) can be used as a biomarker for diseases such as cancer, diabetes, atherosclerosis, and sepsis. In this study, we demonstrated the ability of nanozymes to displace the natural derived enzyme in enzyme-based assays for the measurement of LPC. Synthesized polyvinylpyrrolidone-stabilized platinum-ruthenium nanozymes (PVP/PtRu NZs) had a uniform size of 2.48 ± 0.24 nm and superb peroxidase-mimicking activity. We demonstrated that the nanozymes had high activity over a wide pH and temperature range and high stability after long-term storage. The LPC concentration could be accurately analyzed through the absorbance and fluorescence signals generated by the peroxidation reaction using the synthesized nanozyme with substrates such as 3,3',5,5'-tetramethylbenzidine (TMB) and 10-acetyl-3,7-dihydroxyphenoxazine (Ampliflu™ Red). LPC at a concentration of 0-400 µM was used for the analysis, and the coefficient of determination (R2) was 0.977, and the limit of detection (LOD) was 23.1 µM by colorimetric assay. In the fluorometric assay, the R2 was 0.999, and the LOD was 8.97 µM. The spiked recovery values for the determination of LPC concentration in human serum samples were 102-115%. Based on these results, we declared that PVP/PtRu NZs had an ability comparable to that of the native enzyme horseradish peroxidase (HRP) in the enzyme-based LPC detection method.

Struggling to Stay Engaged During Adversity: A Daily Investigation of Frontline Service Employees' Job Insecurity and the Moderating Role of Ethical Leader Behavior.

Drawing on conservation of resources theory, this study examined the moderating role of ethical leader behavior in the effects of daily perceived job insecurity on work outcomes the next day (i.e., work engagement and customer-directed helping) through occupational regret the next morning among frontline service employees working in adverse work situations (i.e., the coronavirus disease pandemic). Using experience sampling method, data were collected from 135 frontline service employees across five consecutive workdays. The results showed that daily perceived job insecurity had a negative indirect effect on work engagement and customer-directed helping the next day through (increased) occupational regret the next day in the morning. In addition, ethical leader behavior moderated the negative indirect effect of daily perceived job insecurity on next-day work engagement and customer-directed helping through next-morning occupational regret. Specifically, these negative effects were especially stronger among employees who had observed low levels of ethical leader behavior the previous day. The theoretical implications of the present findings for researchers and their practical implications for managers are discussed.

Mesoporous platinum nanoparticles as a peroxidase mimic for the highly sensitive determination of C-reactive protein.

The generation of a mesoporous structure in platinum nanoparticles can effectively enhance physical and chemical properties. In this study, mesoporous platinum nanoparticles (MPNs) were synthesized by a soft template-mediated one-pot chemical method. To develop a mesoporous structure, Pluronic F-127 was employed. The Pluronic F-127 surfactant forms self-assembled micelles, and the micelles act as the pore-directing agents in the synthesis of nanoparticles. Scanning electron microscopy results revealed that the MPN had a uniform size of 70 nm on average and a distinct mesoporous structure. The development of a concave mesoporous structure on the surface of the MPNs can increase the surface area and facilitate the efficient transport of reactants. The synthesized MPNs exhibited peroxidase-like activity. Furthermore, the MPNs showed excellent catalytic efficiency compared to HRP, due to the high surface area derived from the presence of the mesoporous structure. The peroxidase-like MPNs were applied to the enzyme-linked immunosorbent assay (ELISA) of C-reactive protein (CRP). The MPN-based ELISA exhibited sensitive CRP detection in the range from 0.24 to 7.8 ng/mL with a detection limit of 0.13 ng/mL. Moreover, the recoveries of the CRP concentrations in spiked human serum were 98.6% and 102%. These results demonstrate that as a peroxidase mimic, the MPNs can replace the natural enzymes in conventional ELISA for sensitive CRP detection.

Having control or lacking control? Roles of job crafting and service scripts in coping with customer incivility.

Despite previous studies that examined factors that would help service employees cope with customer incivility, the role of employee-initiated job strategies has rarely been explored in the context of customer incivility. Drawing on the job demand-control model, we proposed that a high-control job strategy (such as job crafting) alleviates the deleterious effect of customer incivility on job performance through emotional exhaustion, whereas a low-control job strategy (such as service scripts) aggravates this effect. To test the proposed moderated mediation effects, we collected three-wave data from 272 hotel employees and their 54 team leaders over a 6-month period. As predicted, job crafting and service scripts performed contrasting moderating functions. Specifically, the customer incivility-emotional exhaustion relationship was weaker for employees who engaged in job crafting more often than for those who did not. Job crafting also mitigated the negative indirect effect of customer incivility on job performance through emotional exhaustion. In contrast, the customer incivility-emotional exhaustion relationship was more pronounced among employees who used service scripts more often. Service scripts further exacerbate the negative indirect effect of customer incivility on job performance through emotional exhaustion. These findings have theoretical and practical implications for occupational health research. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Do Organizational Health Climates and Leader Health Mindsets Enhance Employees' Work Engagement and Job Crafting Amid the Pandemic?

Although the COVID-19 pandemic has resulted in many health- and stress-related symptoms among employees, surprisingly few studies have assessed the effect of a health-promoting organizational climate or leadership on employee work outcomes. To fill this gap, our research proposed and tested a moderated mediation model involving perceived organizational health climate (POHC), leader health mindset (LHM), work engagement, and job crafting. Our propositions were tested using two-wave data collected from 301 South Korean employees. As predicted, POHC was positively related to employees' job crafting, and this relationship was mediated by work engagement. Moreover, the positive relationship between POHC and work engagement and the indirect effect of POHC on job crafting through work engagement were more pronounced when LHM was high than when it was low. These findings support the job demands-resources model and social exchange theory and have implications for helping employees maintain their work attitudes and behavior in times of crisis.

Au nanoparticle-hydrogel nanozyme-based colorimetric detection for on-site monitoring of mercury in river water.

A sensitive on-site mercury sensing platform was developed for simple and effective monitoring of mercury levels in the field. The simple and practical mercury detection system was designed by integrating an Au nanoparticle-PEG hydrogel block nanozyme (Au-HBNz) into a polymer film-based colorimetric device. Upon addition of Hg2+ ions, Au-HBNz exhibited excellent peroxidase-like activity, catalyzing the oxidation of 3,3',5,5'-tetramethylbenzidine into a blue-colored product, which has a maximum absorbance at 652 nm. The resulting color intensity change was evaluated using a smartphone for simple and rapid Hg2+ detection with a broad detection range (0.008-20 µg∙mL-1) and a linear concentration-response relationship (R2 = 0.96). The detection limit (1.10 ng∙mL-1) was lower than the maximum permissible Hg2+ levels in drinking water set by the World Health Organization (6 ng∙mL-1) and U.S. Environmental Protection Agency (2 ng∙mL-1). The recoveries of Hg2+ determination in river water by spiking Hg2+ samples ranged from 92 to 106%, which indicated high validity and applicability of the Hg2+ detection system for field measurements. Thus, the developed sensor enables highly selective and efficient real-time monitoring of Hg2+.

The Power of Family Support: The Long-Term Effect of Pre-COVID-19 Family Support on Mid-COVID-19 Work Outcomes.

While COVID-19 has triggered a vast amount of research on the effect of the pandemic on employee outcomes, little information is known about how the family-to-work interface affects long-term work outcomes during the pandemic. Drawing on the work-home resources model, this study proposes that family support provided before the onset of COVID-19 has a positive indirect effect on job performance and organizational citizenship behavior (OCB) after the onset, by decreasing emotional exhaustion. To test this proposition, we collected two-wave data from 211 South Korean employees over a 17-month period. As predicted, after controlling for employees' pre-COVID-19 emotional exhaustion, job performance, and OCB, pre-COVID-19 family support was found to exert a significant indirect effect on mid-COVID-19 job performance (b = 0.024, 95% CI = [0.003, 0.071], abcs = 0.027) and OCB (b = 0.031, 95% CI = [0.001, 0.084], abcs = 0.033), through mid-COVID-19 emotional exhaustion. This finding suggests that family support has a positive longitudinal effect on work outcomes for employees during the pandemic.

Genome Analysis of Nicotinamide Adenine Dinucleotide-Independent Mycoplasma synoviae Isolates From Korea.

Mycoplasma synoviae (MS) is an avian pathogen that causes respiratory disease, infectious synovitis, and eggshell apex abnormalities in chickens. Nicotinamide adenine dinucleotide (NAD)-independent MS was first reported in 1975. Despite the atypical traits of NAD-independent MS, its independence from NAD has not been studied. In this study, we isolated five NAD-independent strains from Korea and assembled their genomes using sequencing reads obtained from Illumina and Oxford Nanopore Technology platforms. The assembled genomes were compared with the genomes of MS-H vaccine strain and type strain WVU1853. We found that the coding sequences of nicotinate phosphoribosyltransferase and glycerol-3-phosphate acyltransferase, and a unique coding sequence were present only in the genomes of NAD-independent isolates.

Death-Associated Protein 6 (Daxx) Alleviates Liver Fibrosis by Modulating Smad2 Acetylation.

Transforming growth factor-ß (TGF-ß) has been identified as an inducer of hepatocyte epithelial-mesenchymal transition (EMT), which triggers liver fibrosis. Death-associated protein 6 (Daxx) is known to be associated with the TGF-ß-induced apoptotic pathway, but the function of Daxx in liver fibrosis remains unknown. This study aimed to elucidate the role of Daxx in liver fibrosis. We used liver fibrosis tissues from humans and mice to assess Daxx expression. EMT properties and TGF-ß signaling pathway activation were investigated in the Daxx-overexpressing FL83B cell line. The therapeutic effect of Daxx was investigated in a mouse model of liver fibrosis by the hydrodynamic injection of plasmids. The expression of Daxx was markedly decreased in hepatocytes from fibrotic human and mouse livers, as well as in hepatocytes treated with TGF-ß in vitro. The overexpression of Daxx inhibited the EMT process by interfering with the TGF-ß-induced phosphorylation of Smad2. Coimmunoprecipitation analysis confirmed that Daxx reduced the transcriptional activity of Smad2 by binding to its MH1 domain and interfering with Smad2 acetylation. In addition, the therapeutic delivery of Daxx alleviated liver fibrosis in a thioacetamide-induced fibrosis mouse model. Overall, our results indicate that Daxx could be a potential therapeutic target to modulate fibrogenesis, as well as a useful biomarker for liver fibrosis.

Mistreatment from Multiple Sources: Interaction Effects of Abusive Supervision, Coworker Incivility, and Customer Incivility on Work Outcomes.

Despite the large body of research on workplace mistreatment, surprisingly few studies have examined the interaction effect of multiple interpersonal stressors on employee outcomes. To fill this gap, our research aimed to test the moderating effects of coworker incivility and customer incivility on the relationship between abusive supervision, emotional exhaustion, and job performance. Analyses conducted on 651 South Korean frontline service employees revealed that abusive supervision exerted a significant indirect effect on job performance through emotional exhaustion. Customer incivility strengthened the positive relationship between abusive supervision and emotional exhaustion, as well as the indirect effect of abusive supervision on job performance through emotional exhaustion. Our post hoc analysis demonstrated a three-way interaction between abusive supervision, coworker incivility, and customer incivility; the relationship between abusive supervision and emotional exhaustion was significantly positive only when coworker incivility was high and customer incivility was low. We discuss the implications of our findings for theory and practice.

Complete Genome Sequence of Mycoplasma gallisepticum Strain KUVMG001, an Isolate from South Korea.

Mycoplasma gallisepticum causes chronic respiratory diseases in poultry and economic losses to the chicken and turkey industry. We report the complete genome sequence of the field isolate strain KUVMG001 of Mycoplasma gallisepticum from South Korea.

PVP-stabilized PtRu nanozymes with peroxidase-like activity and its application for colorimetric and fluorometric glucose detection.

Nanozymes have significant advantages over natural enzymes. The intrinsic peroxidase-like activity of Pt-based nanomaterials can be enhanced by alloying with other transition metals, such as Ru, that have great catalytic activity. In this study, we used polyvinylpyrrolidone (PVP) to synthesize well-dispersed and homogeneous nanostructures. PVP-stabilized Pt-Ru nanozymes (PVP/PtRu NZs) were synthesized and characterized. The PVP/PtRu NZs had an average size of 3.54 ±â€¯0.84 nm and exhibited an intense peroxidase-like activity. The PVP/PtRu NZs were used as peroxidase mimics for colorimetric and fluorometric glucose determination by the glucose oxidase and PVP/PtRu NZs cascade reaction. In the colorimetric assay, the linearly detectable range was 0.25-3.0 mM, with an R2 and limit of detection (LOD) of 0.988 and 138 µM, respectively. In the fluorometric assay, a linear relationship was found when the glucose concentration was between 5.0 and 300 µM (R2 = 0.997), with an LOD of 1.11 µM. Compared to the colorimetric assay, the fluorometric assay had greater sensitivity and a lower detection limit for the determination of glucose. Moreover, the PVP/PtRu NZs had high storage stability over a month and great recovery values in human serum and artificial urine, with a range of 94-106 %. From these results, PVP/PtRu NZs are expected to be used as promising peroxidase mimics in various fields such as biosensing, pharmaceutical processing, and the food industry.

Cell-based electrochemical cytosensor for rapid and sensitive evaluation of the anticancer effects of saponin on human malignant melanoma cells.

Discovering new anticancer agents and analyzing their activities is a vital part of drug development, but it requires a huge amount of time and resources, leading to the increasing demands for more-effective techniques. Herein, a novel and simple cell-based electrochemical biosensor, referred to as a cytosensor, was proposed to investigate the electrochemical behavior of human skin malignant melanoma (SK-MEL28) cells and the anticancer effect of saponin on cell viability. To enhance both electrocatalytic properties and biocompatibility, gold nanoparticles were electrochemically deposited onto a conductive substrate, and poly-L-lysine was further added to the electrode surface. Electric signals from SK-MEL28 cells on the electrodes were obtained from cyclic voltammetry and differential pulse voltammetry. The cathodic peak current was proportional to the cell viability and showed a detection range of 2,880-40,000 cells per device with an excellent linear cell number-intensity relationship (R2= 0.9952). Furthermore, the anticancer effect of saponin on SK-MEL28 cells was clearly established at concentrations higher than 20 µM, which was highly consistent with conventional assays. Moreover, the developed electrochemical cytosensor for evaluating anticancer effects enabled rapid (<2 min), sensitive (LOQ: 2,880cells/device), and non-invasive measurements, thus providing a new avenue for assessing the anticancer drugs in vitro.