CRISPR-based genome editing of a diurnal rodent, Nile grass rat (Arvicanthis niloticus).

BACKGROUND: Diurnal and nocturnal mammals have evolved distinct pathways to optimize survival for their chronotype-specific lifestyles. Conventional rodent models, being nocturnal, may not sufficiently recapitulate the biology of diurnal humans in health and disease. Although diurnal rodents are potentially advantageous for translational research, until recently, they have not been genetically tractable. The present study aims to address this major limitation by developing experimental procedures necessary for genome editing in a well-established diurnal rodent model, the Nile grass rat (Arvicanthis niloticus). RESULTS: A superovulation protocol was established, which yielded nearly 30 eggs per female grass rat. Fertilized eggs were cultured in a modified rat 1-cell embryo culture medium (mR1ECM), in which grass rat embryos developed from the 1-cell stage into blastocysts. A CRISPR-based approach was then used for gene editing in vivo and in vitro, targeting Retinoic acid-induced 1 (Rai1), the causal gene for Smith-Magenis Syndrome, a neurodevelopmental disorder. The CRISPR reagents were delivered in vivo by electroporation using an improved Genome-editing via Oviductal Nucleic Acids Delivery (i-GONAD) method. The in vivo approach produced several edited founder grass rats with Rai1 null mutations, which showed stable transmission of the targeted allele to the next generation. CRISPR reagents were also microinjected into 2-cell embryos in vitro. Large deletion of the Rai1 gene was confirmed in 70% of the embryos injected, demonstrating high-efficiency genome editing in vitro. CONCLUSION: We have established a set of methods that enabled the first successful CRISPR-based genome editing in Nile grass rats. The methods developed will guide future genome editing of this and other diurnal rodent species, which will promote greater utility of these models in basic and translational research.

High-intensity interval training ameliorates postnatal immune activation-induced mood disorders through KDM6B-regulated glial activation.

Postnatal immune activation (PIA) induces persistent glial activation in the brain and causes various neuropathologies in adults. Exercise training improves stress-related mood disorders; however, the role of exercise in psychiatric disorders induced by early-life immune activation and the association between exercise training and glial activation remain unclear. We compared the effects of different exercise intensities on the PIA model, including high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT). Both HIIT and MICT in adolescent mice inhibited neuroinflammation, remodeled synaptic plasticity, and improved PIA-induced mood disorders in adulthood. Importantly, HIIT was superior to MICT in terms of reducing inflammation and increasing body weight. RNA-seq of prefrontal cortex (PFC) tissues revealed a gene expression pattern, confirming that HIIT was more effective than MICT in improving brain glial cell activation through epigenetic modifications of KDM6B. We investigated the role of KDM6B, a specific histone lysine demethylation enzyme - histone 3 lysine 27 demethylase, in inhibiting glial activation against PIA-induced depression and anxiety by regulating the expression of IL-4 and brain-derived neurotrophic factor (BDNF). Overall, our data support the idea that HIIT improves PIA-induced mood disorders by regulating KDM6B-mediated epigenetic mechanisms and indicate that HIIT might be superior to MICT in improving mood disorders with PIA in mice. Our findings provide new insights into the treatment of anxiety and depression disorders.

Nicotinamide mononucleotide maintains cytoskeletal stability and fortifies mitochondrial function to mitigate oocyte damage induced by Triocresyl phosphate.

Triocresyl phosphate (TOCP) was commonly used as flame retardant, plasticizer, lubricant, and jet fuel additive. Studies have shown adverse effects of TOCP on the reproductive system. However, the potential harm brought by TOCP, especially to mammalian female reproductive cells, remains a mystery. In this study, we employed an in vitro model for the first time to investigate the effects of TOCP on the maturation process of mouse oocytes. TOCP exposure hampered the meiotic division process, as evidenced by a reduction in the extrusion of the first polar body from oocytes. Subsequent research revealed the disruption of the oocyte cell cytoskeleton induced by TOCP, resulting in abnormalities in spindle organization, chromosome alignment, and actin filament distribution. This disturbance further extended to the rearrangement of organelles within oocytes, particularly affecting the mitochondria. Importantly, after TOCP treatment, mitochondrial function in oocytes was impaired, leading to oxidative stress, DNA damage, cell apoptosis, and subsequent changes of epigenetic modifications. Supplementation with nicotinamide mononucleotide (NMN) alleviated the harmful effects of TOCP. NMN exerted its mitigating effects through two fundamental mechanisms. On one hand, NMN conferred stability to the cell cytoskeleton, thereby supporting nuclear maturation. On the other hand, NMN enhanced mitochondrial function within oocytes, reducing the excess reactive oxygen species (ROS), restoring meiotic division abnormalities caused by TOCP, preventing oocyte DNA damage, and suppressing epigenetic changes. These findings not only enhance our understanding of the molecular basis of TOCP induced oocyte damage but also offer a promising avenue for the potential application of NMN in optimizing reproductive treatment strategies.

Melatonin improves mouse oocyte quality from 2-ethylhexyl diphenyl phosphate-induced toxicity by enhancing mitochondrial function.

2-Ethylhexyl diphenyl phosphate (EHDPP) is a representative organophosphorus flame retardant (OPFR) that has garnered attention due to its widespread use and potential adverse effects. EHDPP exhibits cytotoxicity, genotoxicity, developmental toxicity, and endocrine disruption. However, the toxicity of EHDPP in mammalian oocytes and the underlying mechanisms remain poorly understood. Melatonin is a natural free radical scavenger that has demonstrated cytoprotective properties. In this study, we investigated the effect of EHDPP on mouse oocytes in vitro culture system and evaluated the rescue effect of melatonin on oocytes exposed to EHDPP. Our results indicated that EHDPP disrupted oocyte maturation, resulting in the majority of oocytes arrested at the metaphase I (MI) stage, accompanied by cytoskeletal damage and elevated levels of reactive oxygen species (ROS). Nevertheless, melatonin supplementation partially rescued EHDPP-induced mouse oocyte maturation impairment. Results of single-cell RNA sequencing (scRNA-seq) analysis elucidated potential mechanisms underlying these protective effects. According to the results of scRNA-seq, we conducted further tests and found that EHDPP primarily disrupts mitochondrial distribution and function, kinetochore-microtubule (K-MT) attachment, DNA damage, apoptosis, and histone modification, which were rescued upon the supplementation of melatonin. This study reveals the mechanisms of EHDPP on female reproduction and indicates the efficacy of melatonin as a therapeutic intervention for EHDPP-induced defects in mouse oocytes.

Exploring the associations between competence in dementia care and work attitudes among formal caregivers in nursing homes.

AIMS: Based on the two-factor model of caregiving appraisals, this study aims to (1) investigate the relationships between competence in dementia care and job satisfaction (work attitudes in positive aspect) and turnover intention (work attitudes in negative aspect) among formal caregivers in nursing homes, and (2) examine the mediating roles of positive aspects of caregiving (caregiving appraisals in positive aspect) and caregiving burden (caregiving appraisals in negative aspect) in the above associations. DESIGN: A cross-sectional design was used. Structural equation modelling was employed to test the proposed model. STROBE checklist guides the reporting of this study. METHODS: Using the multistage cluster sampling method, 407 formal caregivers were selected from 43 nursing homes across 7 districts/counties in China. RESULTS: The proposed model shows a good model fit. Competence in dementia care shows significant positive associations with increased job satisfaction and decreased turnover intention among formal caregivers in nursing homes. Caregiving burden and positive aspects of caregiving mediate the relationships between competence in dementia care and both job satisfaction and turnover intention. Furthermore, the relationship between positive aspects of caregiving and job satisfaction is stronger than that with turnover intention, but the relationship between caregiving burden and turnover intention is not stronger than that with job satisfaction. CONCLUSIONS: The results demonstrate that the two-factor model of caregiving appraisals effectively elucidates the associations and underlying mechanisms between competence in dementia care and formal caregivers' work attitudes. Specifically, two crucial conclusions are drawn: (1) competence in dementia care is associated with higher levels of job satisfaction and lower levels of turnover intention among formal caregivers in nursing homes; (2) caregiving burden and positive aspects of caregiving serve as parallel mediators in these associations. IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE: Policymakers and nursing homes managers should implement a series of measures aimed at formal caregivers in nursing home. Specifically, allocating more resources to enhance the competence in dementia care of formal caregivers is crucial, given its significant association with elevated job satisfaction and reduced turnover intention. Besides, positive and negative caregiving appraisals emerge as proximal factors influencing work attitudes of formal caregivers. Therefore, intervention projects focused on formal caregivers in nursing home should target enhancing positive experiences and alleviating caregiving burden. PATIENT OR PUBLIC CONTRIBUTION: No patient or public contribution.

Intergenerational Caregiving Patterns and Cognitive Health among the Sandwich Generation Within Four-Generation Families.

This study aims to investigate whether generational differences in intergenerational caregiving patterns (caring for parents only, caring for grandchildren only, and caring for parents and grandchildren simultaneously) are associated with cognitive health disparities among the sandwich generation within four-generation families, drawing upon the theories of intergenerational solidarity and intergenerational stake. Moreover, this study seeks to identify mediators that help explain these disparities. A nationally representative sample of 8,065 respondents was drawn from the 2011 and 2018 waves of the China Health and Retirement Longitudinal Study. The findings reveal that the sandwich generation caring for grandchildren only, as well as those caring for grandchildren and parents simultaneously, exhibit better cognitive health. However, caregiving for parents only is not significantly related to their cognitive health. This study identifies the inability to reduce depressive symptoms as a mediator explaining the insignificant association between caregiving for parents only and the cognitive health of the sandwich generation. The findings underscore the importance of offering support to the sandwich generation within four-generation families to enhance their cognitive health. Moreover, it is imperative to distinguish between different intergenerational caregiving patterns based on generational differences among the sandwich generation, with a specific emphasis on allocating public resources aimed at promoting cognitive health for those engaged in caring for parents.

Lysine and Arginine Reactivity and Transformation Products during Peptide Chlorination.

Chlorine reactions with peptide-bound amino acids form disinfection byproducts and contribute to pathogen inactivation by degrading protein structure and function. Peptide-bound lysine and arginine are two of the seven chlorine-reactive amino acids, but their reactions with chlorine are poorly characterized. Using N-acetylated lysine and arginine as models for peptide-bound amino acids and authentic small peptides, this study demonstrated conversion of the lysine side chain to mono- and dichloramines and the arginine side chain to mono-, di-, and trichloramines in ≤0.5 h. The lysine chloramines formed lysine nitrile and lysine aldehyde at ∼6% yield over ∼1 week. The arginine chloramines formed ornithine nitrile at ∼3% yield over ∼1 week but not the corresponding aldehyde. While researchers hypothesized that the protein aggregation observed during chlorination arises from covalent Schiff base cross-links between lysine aldehyde and lysine on different proteins, no evidence for Schiff base formation was observed. The rapid formation of chloramines and their slow decay indicate that they are more relevant than the aldehydes and nitriles to byproduct formation and pathogen inactivation over timescales relevant to drinking water distribution. Previous research has indicated that lysine chloramines are cytotoxic and genotoxic to human cells. The conversion of lysine and arginine cationic side chains to neutral chloramines should alter protein structure and function and enhance protein aggregation by hydrophobic interactions, contributing to pathogen inactivation.

Chloramination of Nitromethane: Incomplete Chlorination and Unexpected Substitution Reaction.

Ozone is commonly used as a predisinfectant in potable water reuse treatment trains. Nitromethane was recently found as a ubiquitous ozone byproduct in wastewater, and the key intermediate toward chloropicrin during subsequent secondary disinfection of ozonated wastewater effluent with chlorine. However, many utilities have switched from free chlorine to chloramines as a secondary disinfectant. The reaction mechanism and kinetics of nitromethane transformation by chloramines, unlike those for free chlorine, are unknown. In this work, the kinetics, mechanism, and products of nitromethane chloramination were studied. The expected principal product was chloropicrin, because chloramines are commonly assumed to react similarly to, although more slowly than, free chlorine. Different molar yields of chloropicrin were observed under acidic, neutral, and basic conditions, and surprisingly, transformation products other than chloropicrin were found. Monochloronitromethane and dichloronitromethane were detected at basic pH, and the mass balance was initially poor at neutral pH. Much of the missing mass was later attributed to nitrate formation, from a newly identified pathway involving monochloramine reacting as a nucleophile rather than a halogenating agent, through a presumed SN2 mechanism. The study indicates that nitromethane chloramination, unlike chlorination, is likely to produce a range of products, whose speciation is a function of pH and reaction time.

Community support, social isolation and older adults' life satisfaction: evidence from a national survey in China.

OBJECTIVES: Despite the recognized importance of community social service and community built facility for enhancing older adults' life satisfaction, the mechanisms underlying their relationship have not been thoroughly examined. This study aims to complement the existing knowledge by investigating the mediating role of social disconnectedness and loneliness in the association between community support and life satisfaction among older adults. METHODS: Using data from the 2018 China Longitudinal Aging Social Survey, the study analyzes responses from 9,874 Chinese older adults (mean age = 71.30 years, SD = 7.30). We conducted descriptive statistics and Pearson's correlation to explore the variables. This study also used Mplus 8.0 to conduct a path analysis model that evaluated both the direct and indirect effects of community social service and built facility on life satisfaction. Social disconnectedness and loneliness were included as mediating variables in this model. RESULTS: The present study results show that both community social service and community built facility are positively associated with life satisfaction among older adults, and community social service is more imporatant for enhancing the life satisfaction. In addition, these associations are mediated by social disconnectedness and loneliness. CONCLUSION: Our research suggests that strengthening community social service programs and improving the built environment can reduce social disconnectedness and loneliness among older adults, ultimately enhancing their life satisfaction. Specifically, policymakers can invest in targeted interventions to enhance social connectedness and reduce loneliness, with the goal of improving the overall well-being of older adults.

The impact of widowhood on mental health of older adults.

Widowhood is identified as a risk factor for older adults' mental health, however, the underlying mechanisms and protective factors in this association has not been fully revealed. In order to add to the current knowledge, this study investigates the mediating roles of economic, social and psychological resources and the moderating role of community support in the relationship between widowhood and mental health. A sample of 7913 Chinese older people (Mean age = 71.14, SD = 7.19) is obtained from the 2018 wave of China Longitudinal Aging Social Survey. Results indicates that widowhood is negatively associated with older adults' mental health. Economic, social and psychological resources partially mediate the above association. Furthermore, the effect of widowhood is weaker for older people with more rather than less community support. This study not only illuminates the potential mechanisms of how widowhood influence mental health theoretically, but also provides valuable implications.

Regulation of stem cell fate and function by using bioactive materials with nanoarchitectonics for regenerative medicine.

Nanoarchitectonics has emerged as a post-nanotechnology concept. As one of the applications of nanoarchitectonics, this review paper discusses the control of stem cell fate and function as an important issue. For hybrid nanoarchitectonics involving living cells, it is crucial to understand how biomaterials and their nanoarchitected structures regulate behaviours and fates of stem cells. In this review, biomaterials for the regulation of stem cell fate are firstly discussed. Besides multipotent differentiation, immunomodulation is an important biological function of mesenchymal stem cells (MSCs). MSCs can modulate immune cells to treat multiple immune- and inflammation-mediated diseases. The following sections summarize the recent advances of the regulation of the immunomodulatory functions of MSCs by biophysical signals. In the third part, we discussed how biomaterials direct the self-organization of pluripotent stem cells for organoid. Bioactive materials are constructed which mimic the biophysical cues of in vivo microenvironment such as elasticity, viscoelasticity, biodegradation, fluidity, topography, cell geometry, and etc. Stem cells interpret these biophysical cues by different cytoskeletal forces. The different cytoskeletal forces lead to substantial transcription and protein expression, which affect stem cell fate and function. Regulations of stem cells could not be utilized only for tissue repair and regenerative medicine but also potentially for production of advanced materials systems. Materials nanoarchitectonics with integration of stem cells and related biological substances would have high impacts in science and technology of advanced materials.

Construction of Dual-Shell Mo2C/C Microsphere towards Efficient Electromagnetic Wave Absorption.

Carbon-based carbides have attracted tremendous attention for electromagnetic energy attenuation due to their adjustable dielectric properties, oxidation resistance, and good chemical stability. Herein, we reasonably regulate the growth of dopamine hydrochloride on the surface of the Mo-glycerate (Mo-GL) microsphere and then transform the resultant Mo-polydopamine (Mo-PD) microsphere into a dual-shell Mo2C/C (DS-Mo2C/C) microsphere in a high-temperature pyrolysis process under an inert atmosphere. It is found that the pyrolysis temperature plays an important role in the graphitization degree of the carbon matrix and internal architecture. The fabrication of a dual-shell structure can be propitious to the optimization of impedance matching, and the introduction of Mo2C nanoparticles also prompts the accumulation of polarization loss. When the pyrolysis temperature reaches 800 °C, the optimized composite of DS-Mo2C/C-800 exhibits good EM absorption performance in the frequency range of 2.0-18.0 GHz. DS-Mo2C/C-800's qualified bandwidth can reach 4.4 GHz at a matching thickness of 1.5 mm, and the integrated qualified bandwidth (QBW) even exceeds 14.5 GHz with a thickness range of 1.5-5.0 mm. The positive effects of the dual-shell structure and Mo2C nanoparticles on EM energy attenuation may render the DS-Mo2C/C microsphere as a promising candidate for lightweight and broad bandwidth EM absorption materials in the future.

Formation and Fate of Nitromethane in Ozone-Based Water Reuse Processes.

Ozonation is widely used in wastewater reclamation treatment trains, either for micropollutant control or as a disinfectant and preoxidant in certain reuse processes. We recently found that ozonation of secondary effluent produces nitromethane, which can be efficiently transformed to genotoxic halonitromethanes by chlorination. In this work, the fate of nitromethane through water reuse treatment trains was characterized by analyzing samples from five reuse operations employing ozone. Nitromethane was poorly (<50%) rejected by reserve osmosis (RO), not removed by, and in some cases, increased by ultraviolet/advanced oxidation processes (UV/AOP). Sufficient nitromethane remained after advanced treatment that when chlorine was added to mimic secondary disinfection, halonitromethane formation was consistently observed. In contrast, biological activated carbon removed most (>75%) nitromethane. Bench-scale experiments were conducted to verify low removal by RO in clean systems and with wastewater effluent and to quantify the kinetics of direct and indirect photolysis of nitromethane in UV/AOP. An explanation for increasing nitromethane concentration during AOP is proposed. These results indicate that nitromethane presents a unique hazard to direct potable reuse systems, due to its ubiquitous formation during wastewater ozonation, poor removal by RO and UV/AOP, and facile conversion into genotoxic halonitromethanes upon chlorine addition.

Transformation of N-Methylamine Drugs during Wastewater Ozonation: Formation of Nitromethane, an Efficient Precursor to Halonitromethanes.

Potable reuse of wastewater is expanding, and ozonation for water reuse is becoming more common, either as a preoxidant before membranes or as part of ozone/biological activated carbon (O3/BAC) systems. However, previous research has demonstrated that ozone drastically increases the formation potential of genotoxic halonitromethanes (HNMs), including during O3/BAC. Chloropicrin, the most common HNM, is synthesized by chlorinating nitromethane, suggesting that nitromethane may be the immediate precursor of chloropicrin, although nitromethane is unlikely to occur naturally in wastewater. We hypothesized that wastewater ozonation forms nitromethane, which would be the key intermediate toward HNMs. Ozonation of wastewater effluent was shown to form abundant nitromethane, which explained the majority (in one case, all) of subsequent chloropicrin formation. Next, we investigated a suspected category of nitromethane precursor: stimulant drugs, such as ephedrine and methamphetamine, and certain antidepressants. These drugs all feature N-methylamine functional groups, and certain N-alkylamines have been shown to produce primary nitroalkanes upon ozonation. Ozonation of N-methylamine drugs ubiquitously formed nitromethane, typically at >50% yield. Subsequent chlorination converted nitromethane to chloropicrin. The reaction mechanism was investigated to understand the variation in nitromethane yield between different precursors. These results suggest that nitromethane fate during reuse and nitromethane control should be investigated.

The relationship between bullying victimization and problematic behaviors: A focus on the intrapersonal emotional competence and interpersonal social competence.

BACKGROUND: Evidence consistently demonstrated that bullying victimization was associated with problematic behaviors among adolescents. However, scant attention has been given to simultaneous comparisons of the impacts of two distinct forms of victimization, traditional bullying victimization and cyberbullying victimization. In addition, the mechanisms underlying the relationship between bullying victimization and problem behavior remain inadequately explored. OBJECTIVE: This study aimed to examine the correlation between bullying victimization and problematic behaviors, as well as the mediating roles of intrapersonal emotional competence and interpersonal social competence. PARTICIPANTS AND SETTING: A sample of 26,450 adolescents with a mean age of 15.44 (SD = 0.56) across nine countries was derived from the Study on Social and Emotional Skills (SSES). METHODS: Data analysis was conducted using structural equation modeling, comprising three key components: the measurement model, the structural model, and the bootstrapping analysis for mediating effects. RESULTS: Both traditional bullying and cyberbullying victimization exhibited positive correlations with problematic behaviors, with cyberbullying victimization demonstrating a stronger effect. The mediating effects of intrapersonal emotional competence and interpersonal social competence were observed in the correlation between bullying victimization and problematic behaviors. CONCLUSIONS: This study not only contributed to our comprehension of the underlying mechanisms connecting bullying victimization and adolescent problematic behaviors, but also holds significance for policy development and practice.

The Long Arm of Childhood Bullying Victimization: Associations with Social Isolation, Gender Differences and Depression in Later Life.

The association between childhood bullying victimization and depression has been well-explored among young adults, but little is known about whether this relationship persists into later life stages, specifically during middle-aged and older phases. Moreover, the intricate mechanisms underpinning this association and the potential existence of gender differences within this context remain inadequately elucidated. To address this gap in knowledge, this study aims to investigate the association between childhood bullying victimization and depression in later life, with a focus on exploring the mediating role of social isolation and the moderating roles of gender. A nationally representative sample of 5,070 individuals (mean age = 61.02, SD = 9.48; male = 55%) was drawn from the China Health and Retirement Longitudinal Study. By employing the bootstrapping analysis method, the mediating role of social isolation was examined, and the moderating role of gender was tested through the generation of interaction items. The results reveal a significant association between childhood bullying victimization and severe depression in later life. Additionally, social isolation plays a mediating role in this association between childhood bullying victimization and social isolation, and the association between social isolation and depression, as well as the relationship between social isolation and depression, are both moderated by gender, presenting stronger effects for female groups than for male groups. However, no moderating role of gender is found in terms of the direct association between childhood bullying victimization and depression. These findings highlight the fact that childhood bullying is not only a problem in the immediate term but also a concern that affects individuals across entire life course. This study has implications for healthcare in proactively investigating, diagnosing, and treating depression by inquiring about childhood bullying victimization experiences. Furthermore, intervention policies that aim to reduce social isolation may be particularly beneficial in mitigating the negative associations, especially for female individuals.

The benefits of physical exercise on older adults' cognitive function: A cohort study exploring potential mechanisms.

BACKGROUND: Despite existing studies showing that physical exercise improves cognitive function in older adults either concurrently or in a delayed manner, studies examining these associations simultaneously are rare. Additionally, the underlying mechanisms in these associations remain incompletely understood. OBJECTIVE: This study explores the concurrent and delayed (two years later) associations between physical exercise and older adults' cognitive function. This study also investigates the mediating roles of three negative physical, psychological, and social resources: limitations in daily abilities, depressive mood, and isolation from friends, as well as the moderating roles of cognitive reserve on these associations. DESIGN: A cohort sample of 6646 Chinese older adults (Mean age = 69.28, SD = 7.03) is obtained from the 2016 and 2018 waves of the China Longitudinal Aging Social Survey. Regression analysis was employed to test the concurrent and delayed associations between physical exercise and cognitive function. The bootstrap method was utilized to examine the mediating roles of limitations in daily activities, depression mood, and isolation from friends. Interaction terms were generated to investigate the moderating roles of cognitive reserve. RESULTS: Physical exercise presents concurrent and delayed positive associations with cognitive function. Limitations in daily activities, depressive mood and isolation from friends mediate the above associations. Moreover, cognitive reserve plays a significant role in buffering the concurrent and delayed negative links between depressive mood, isolation from friends, and cognitive function, with larger negative relationships observed for older adults with lower rather than higher levels of cognitive reserve. CONCLUSIONS: This study validates the concurrent and delayed benefits of physical exercise on older adults' cognitive function while elucidating the underlying mechanisms. These findings offer practical implications for health policies and intervention programs aimed at enhancing older adults' cognitive function.

High sensitivity and automatic chemiluminescence detection of glucose and lactate using a spin-disc paper-based device.

This paper reports a spin-disc paper-based device with 10 individual detection units containing electromagnetic modules controlling the sample incubation time before chemiluminescence (CL) signal detection. After the sample was added to the top paper chip and incubated with the enzyme, the electromagnet was turned off to allow contact between the top and bottom paper. The H2O2 generated by the sample flowed vertically to the bottom paper and initiated the oxidase of the luminol to generate the CL signal. After one detection the disc was automatically rotated to the next position to repeat the above detection. The advantage of using the device over the lateral flow and the in situ detection was firstly proved using the detection of H2O2 and the glucose/lactate sample with 5 minute incubation. The CL intensity was increased 300 times/1000 times as the glucose/lactate was incubated for 5 minutes compared to the non-incubated samples. Afterward, the device was employed to separately detect glucose and lactate diluted in PBS, artificial sweat, artificial saliva, and fresh cell culture media. Finally, the device was employed to detect the glucose and lactate in the media collected over the 24 hour culture of PC3 cells. The uptake and production rates of glucose and lactate were correspondingly determined as 0.328 ± 0.015 pmol h-1 per cell and 1.254 ± 0.053 pmol h-1 per cell, respectively. The reported device has wide application potential due to its capabilities in automatic detection of multiple samples with very high sensitivity and small sample volume (down to 0.5 µL).

Interface-mediated synthesis of monodisperse ZnS nanoparticles with sulfate-reducing bacterium culture.

We have created a new method of ZnS nanospheres synthesis. By interface-mediated precipitation method (IMPM), monodisperse ZnS nanoparticles was synthesized on the particle surface of sulfate-reducing bacterium nutritious agar culture. Sulfate-reducing bacterium (SRB) was used as a sulfide producer because of its dissimilatory sulfate reduction capability, meanwhile produced a variety of amino acids acting as templates for nanomaterials synthesis. Then zinc acetate was dispersed into nutritious agar plate. Subsequently agar plate was broken into particles bearing much external surface, which successfully mediated the synthesis of monodisperse ZnS nanoparticles. The morphology of monodisperse ZnS nanospheres and SRB were examined by scanning electron microscopy (SEM), and the microstructure was investigated by X-ray diffraction (XRD). The thermostability of ZnS nanoparticles was determined by thermo gravimetric-differential thermo gravimetric (TG-DTG). The maximum absorption wavelengh was analysed with an ultraviolet-visible spectrophotometer within a range of 199-700 nm. As a result, monodisperse ZnS nanoparticles were successfully synthesized, with an average diameter of 80 nm. Maximum absorption wavelengh was 228 nm, and heat decomposed temperature of monodisperse ZnS nanoparticles was 596°C.

Pollution-Free and Highly Sensitive Lactate Detection in Cell Culture Based on a Microfluidic Chip.

Cell metabolite detection is important for cell analysis. As a cellular metabolite, lactate and its detection play an important role in disease diagnosis, drug screening and clinical therapeutics. This paper reports a microfluidic chip integrated with a backflow prevention channel for cell culture and lactate detection. It can effectively realize the upstream and downstream separation of the culture chamber and the detection zone, and prevent the pollution of cells caused by the potential backflow of reagent and buffer solutions. Due to such a separation, it is possible to analyze the lactate concentration in the flow process without contamination of cells. With the information of residence time distribution of the microchannel networks and the detected time signal in the detection chamber, it is possible to calculate the lactate concentration as a function of time using the de-convolution method. We have further demonstrated the suitability of this detection method by measuring lactate production in human umbilical vein endothelial cells (HUVEC). The microfluidic chip presented here shows good stability in metabolite quick detection and can work continuously for more than a few days. It sheds new insights into pollution-free and high-sensitivity cell metabolism detection, showing broad application prospects in cell analysis, drug screening and disease diagnosis.