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Interaction of biologically relevant proteins with ZnO nanomaterials: A confounding factor for in vitro toxicity endpoints
摘要： The results of in vitro toxicological studies for manufactured nanomaterials (MNs) are often contradictory and not reproducible. Interference of the MNs with assays has been suggested. However, understanding for which materials and how these artefacts occur remains a major challenge. This study investigated interactions between two well-characterized ZnO MNs (NM-110 and NM-111) and lactate dehydrogenase (LDH), and two interleukins (IL-6 and IL-8). Particles (10 to 640 μg/mL) and proteins were incubated for 24 hours in routine in vitro assays test conditions. LDH activity (ODLDH), but not interleukins concentrations, decreased sharply in a dose-dependent manner within an hour after exposure (ODLDH < 60% of ODref for both MNs at 10 μg/mL). A Freundlich adsorption isotherm was successfully applied, indicating multilayer adsorption of LDH. ZnO MNs and LDH had neutral to slightly negative surface charges in dispersion, precluding electrostatic attachment. Particle sedimentation was not a limiting factor. Fast dissolution of ZnO MNs was shown and Zn2+ could play a role in the ODLDH drop. To summarize, ZnO MNs quickly reduced ODLDH due to concentration-dependent adsorption and LDH inhibition by interaction with dissolved Zn. The control of particle interference in toxicological in vitro assays should become mandatory to avoid misleading interpretation of results.
关键词： artefact,pH,interleukin,adsorption,lactate dehydrogenase,dissolution
更新于2025-09-23 15:23:52
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A novel bioreactor for combined magnetic resonance spectroscopy and optical imaging of metabolism in 3D cell cultures
摘要： Purpose: Fluorescence lifetime imaging microscopy (FLIM) of endogenous fluorescent metabolites permits the measurement of cellular metabolism in cell, tissue and animal models. In parallel, magnetic resonance spectroscopy (MRS) of dynamic nuclear (hyper)polarized 13C‐pyruvate enables measurement of metabolism at larger in vivo scales. Presented here are the design and initial application of a bioreactor that connects these 2 metabolic imaging modalities in vitro, using 3D cell cultures. Methods: The model fitting for FLIM data analysis and the theory behind a model for the diffusion of pyruvate into a collagen gel are detailed. The device is MRI‐compatible, including an optical window, a temperature control system and an injection port for the introduction of contrast agents. Three‐dimensional printing, computer numerical control machining and laser cutting were used to fabricate custom parts. Results: Performance of the bioreactor is demonstrated for 4 T1 murine breast cancer cells under glucose deprivation. Mean nicotinamide adenine dinucleotide (NADH) fluorescence lifetimes were 10% longer and hyperpolarized 13C lactate:pyruvate (Lac:Pyr) ratios were 60% lower for glucose‐deprived 4 T1 cells compared to 4 T1 cells in normal medium. Looking at the individual components of the NADH fluorescent lifetime, τ1 (free NADH) showed no significant change, while τ2 (bound NADH) showed a significant increase, suggesting that the increase in mean lifetime was due to a change in bound NADH. Conclusion: A novel bioreactor that is compatible with, and can exploit the benefits of, both FLIM and 13C MRS in 3D cell cultures for studies of cell metabolism has been designed and applied.
关键词： multimodal,optical imaging,bioreactor,magnetic resonance spectroscopy (MRS),nicotinamide adenine dinucleotide (NADH),metabolism,fluorescence lifetime imaging (FLIM),lactate production
更新于2025-09-23 15:22:29
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Measurement of brain lactate during visual stimulation using a long TE semia??LASER sequence at 7 T
摘要： Estimation of metabolic changes during neuronal activation represents a challenge for in vivo MRS, especially for metabolites with low concentration and signal overlap, such as lactate. In this work, we aimed to evaluate the feasibility of detecting lactate during brain activation using a long TE (144 ms) semi-LASER sequence at 7 T. 1H spectra were acquired on healthy volunteers (N = 6) during a paradigm with 15 min of visual stimulation. Outer-volume signals were further attenuated by the use of saturation slabs, and macromolecular signals in the vicinity of the inverted lactate peak were individually fitted with simulated Lorentzian peaks. All spectra were free of artefacts and highly reproducible across subjects. Lactate was accurately quantified with an average Cramér-Rao lower bound of 8%. Statistically significant (P < 0.05, one-tailed t-test) increases in lactate (～10%) and glutamate (～3%) levels during stimulation were detected in the visual cortex. Lactate and glutamate changes were consistent with previous measurements. We demonstrated that quantification of a clear and non-contaminated lactate peak obtained with a long TE sequence has the potential of improving the accuracy of functional MRS studies targeting non-oxidative reaction pathways.
关键词： lactate,functional MRS,long TE,semi-LASER,macromolecules
更新于2025-09-19 17:13:59
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Brief Insights into Cu <sub/>2</sub> O Electrodeposition: Detailed Progressive Voltammetric and Electrogravimetric Analysis of a Copper Lactate System
摘要： The alkaline copper(II) lactate system is the most popular system applied in the electrochemical synthesis of Cu2O films designed for various purposes. The present work describes step by step the mechanism of electrode reactions accompanying the cathodic polarization of the electrode within a potential range from 0 to ?1.0 V in copper lactate based electrolyte. Anodic processes related to the oxidation of products formed during cathodic sweep are also analyzed in detail. The performed studies indicate sequence and mechanisms of reduction of species present in the electrolyte, secondary reduction of products of cathodic reactions as well as oxidation of various species formed at the electrode surface.
关键词： electrogravimetric analysis,electrodeposition,Cu2O,voltammetric analysis,copper lactate
更新于2025-09-16 10:30:52
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Development of a longevous two-species biophotovoltaics with constrained electron flow
摘要： Microbial biophotovoltaics (BPV) offers a biological solution for renewable energy production by using photosynthetic microorganisms as light absorbers. Although abiotic engineering approaches, e.g., electrode modification and device optimization, can enhance the electrochemical communication between living cells and electrodes, the power densities of BPV are still low due to the weak exoelectrogenic activity of photosynthetic microorganisms. Here, we develop a BPV based on a D-lactate mediated microbial consortium consisting of photosynthetic cyanobacteria and exoelectrogenic Shewanella. By directing solar energy from photons to D-lactate, then to electricity, this BPV generates a power density of over 150 mW·m?2 in a temporal separation setup. Furthermore, a spatial-temporal separation setup with medium replenishment enables stable operation for over 40 days with an average power density of 135 mW·m?2. These results demonstrate the electron flow constrained microbial consortium can facilitate electron export from photosynthetic cells and achieve an efficient and durable power output.
关键词： biophotovoltaics,electron flow,microbial consortium,cyanobacteria,renewable energy,D-lactate,Shewanella
更新于2025-09-12 10:27:22
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Laser-Scribed Graphene Electrodes Derived from Lignin for Biochemical Sensing
摘要： Laser scribing of porous graphene electrodes on flexible substrates is of great interest for developing disposable electrochemical biosensors. In this work, we present a new patterning process for highly conductive nitrogen-doped graphene derived from a lignin-based precursor. A CO2 laser scribing process was performed under ambient conditions to produce the porous graphene electrodes from lignin. The obtained nitrogen-doped laser-scribed graphene (N-LSG) is binder-free, hierarchical, and conductive. The interconnected carbon network displayed enhanced electrochemical activity with improved heterogeneous electron transfer rate. These features can be attributed to the high-conductivity of porous N-LSG (down to 2.8 ? per square) and its enriched active edge plane sites. Furthermore, the N-LSG electrodes were decorated with MXene/Prussian Blue (Ti3C2Tx/PB) composite via a simple spray coating process, designed for sensitive detection of analytes. The Ti3C2Tx/PB modified N-LSG electrodes were functionalized with catalytic enzymes for detecting glucose, lactate, and alcohol. The enzyme/Ti3C2Tx/PB/N-LSG electrodes exhibited remarkably enhanced electrochemical activity toward the detection of these biomarkers, making them highly competitive with previously reported on-chip carbon-based biosensors. Therefore, our sensors demonstrate excellent potential for applications in personalized healthcare.
关键词： laser-scribed graphene,MXene,alcohol,lactate,glucose,lignosulfonate,biosensor,high conductivity
更新于2025-09-12 10:27:22
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Low-level laser irradiation potentiates anticancer activity of p-coumaric acid against human malignant melanoma cells
摘要： p-Coumaric acid (PCA) is a kind of phenolic compound, and as one of the cinnamic acid derivatives, it has many biological functions such as antioxidants, anti-inflammatory, antiplatelet, and anticancer activity. Low-level laser irradiation has received increasing interest in the fields of tissue regeneration and wound healing. In this study, the effect of low-level laser irradiation on human fibroblast cells (human dermal fibroblast) and human melanoma cancer cells (A375 and SK-MEL-37) treated with PCA was investigated. The human dermal fibroblast, A375, and SK-MEL-37 cells were exposed to low-level laser at 660-nm wavelength with 3 J/cm2 for 90 s, and then the cells were treated with different concentrations of PCA (0–1000 μg/ml for 24 h), separately. In another experiment, first the cells were treated by PCA and then irradiated with low-level laser as described before. The effect of various irradiation energy (1–6 J/cm2) on the melanoma cells, which were then treated by PCA, was studied. The cell viability using MTT assay and lactate dehydrogenase assay was determined. Morphological changes owing to apoptosis induction by irradiation and PCA were detected by fluorescence microscopy using acridine orange/ethidium bromide double staining. The results showed that pretreatment with low-level laser irradiation and then PCA reduced the survival and growth of melanoma cells more than the early treatment with PCA and then low-level laser irradiation. Lactate dehydrogenase activity was reduced significantly by preirradiation and then PCA treatment in comparison with the dark group in melanoma cells. The cell cytotoxicity at different irradiation energy and then IC50 concentration of PCA was increased up to 3 J/cm2 and then decreased following increasing irradiation energy. The morphology study with light microscopy and apoptotic assay using acridine orange/ethidium bromide dual staining confirmed the MTT results. This study showed that low-level laser irradiation alone is not able to kill human normal fibroblast and human melanoma cancer cells. Preirradiation followed by treatment with PCA did not change the cell viability in human fibroblast significantly but reduced the cell viability in melanoma cells presumably through the apoptosis pathway.
关键词： p-coumaric acid,human melanoma cancer,lactate dehydrogenase,low-level light therapy
更新于2025-09-12 10:27:22
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Hyperpolarized <sup>13</sup> C spectroscopic imaging using single-shot 3D sequences with unpaired adiabatic refocusing pulses
摘要： Hyperpolarized MRI with 13C‐labeled metabolites has enabled metabolic imaging of tumors in vivo. The heterogeneous nature of tumors and the limited lifetime of the hyper-polarization require high resolution, both temporally and spatially. We describe two sequences that make more efficient use of the 13C polarization than previously described single‐shot 3D sequences. With these sequences, the target metabolite resonances were excited using spectral‐spatial pulses and the data acquired using spiral readouts from a series of echoes created using a fast‐spin‐echo sequence employing adiabatic 180° pulses. The third dimension was encoded with blipped gradients applied in an interleaved order to the echo train. Adiabatic inversion pulses applied in the absence of slice selection gradients allowed acquisition of signal from odd echoes, formed by unpaired adiabatic pulses, as well as from even echoes. The sequences were tested on tumor‐bearing mice following intra-venous injection of hyperpolarized [1‐13C]pyruvate. [1‐13C] pyruvate and [1‐13C] lactate images were acquired in vivo with a 4 × 4 × 2 cm3 field of view and a 32 × 32 × 16 matrix, leading to a nominal resolution of 1.25 × 1.25 × 1.25 mm3 and an effective resolution of 1.25 × 1.25 × 4.5 mm3 when the z‐direction point spread function was taken into account. The acquisition of signal from more echoes also allowed for an improvement in the signal‐to‐noise ratio for relaxation times. The pulse sequences described here produced hyperpolarized 13C images with improved resolution and signal‐to‐noise ratio when compared with similar sequences described previously.
关键词： imaging,hyperpolarization,lactate,pyruvate,tumors
更新于2025-09-10 09:29:36