•A review on carbon-based nanomaterials’ applications in sample preparation.•Particular attention is paid to graphene for its growing papers recently.•Research status and perspective of them are also ...discussed.
In this paper, a broad overview on the applications of different carbon-based nanomaterials, including nanodiamonds, fullerenes, carbon nanotubes, graphene, carbon nanofibers, carbon nanocones-disks and nanohorns, as well as their functionalized forms, in sample preparation is provided. Particular attention has been paid to graphene because many papers regarding its application in this research field are becoming available. The distinctive properties, derivatization methods and application techniques of these materials were summarized and compared. According to their research status and perspective, these nanomaterials were classified in four groups (I: graphene and carbon nanotubes; II: carbon nanofibers; III: fullerenes; and IV: nanodiamonds, carbon nanocones/disks and carbon nanohorns) and characteristics and future trends of every group were discussed.
Herein, a chemiluminescence assay with dual signal amplification has been developed based on multi-DNAzymes-functionalized gold nanoparticles (AuNPs) using in situ rolling circle amplification (RCA) ...for ultrasensitive detection of thrombin on microchip. In this assay, AuNPs was functionalized by aptamer and multi-RCA primer for amplification, and thrombin was sandwiched between the aptamer modified on the microchannel and the aptamer linked AuNP. The further amplification was realized by in situ RCA to expand specific oligonucleotides chains on the AuNPs and produce particular multi-DNAzymes. Enhanced chemiluminescence signal was achieved by the catalytic effect of DNAzymes in the luminol-H2O2 system. The sensitivity of detection was greatly improved by the dual amplification of multi-RCA primer modified AuNPs, and RCA. The whole strategy was applied for ultrasensitive and specific detection of thrombin. The chemiluminesce assay of thrombin performed a good linear range of 1–25 pM and the limit of detection was as low as 0.55 pM. The successful determination of thrombin in real human serum sample indicated a great potential in clinical study.
Ultrasensitive thrombin detection by chemiluminescence via a dual signal amplification strategy of functionalized gold nanoparticles and rolling circle amplification. Display omitted
•Ultrasensitive chemiluminesence assay realized by dual signal amplification strategy.•Multichannel microchip increased reaction efficiency and reduced detection time.•Thrombin in serum could be sensitively, selectively and rapidly determined.
Photoassisted steam reforming and dry (CO2) reforming of methane (SRM and DRM) at room temperature with high syngas selectivity have been achieved in the gas‐phase catalysis for the first time. The ...catalysts used are bimetallic rhodium–vanadium oxide cluster anions of Rh2VO1–3−. Both the oxidation of methane and reduction of H2O/CO2 can take place efficiently in the dark while the pivotal step to govern syngas selectivity is photo‐excitation of the reaction intermediates Rh2VO2,3CH2− to specific electronically excited states that can selectively produce CO and H2. Electronic excitation over Rh2VO2,3CH2− to control the syngas selectivity is further confirmed from the comparison with the thermal excitation of Rh2VO2,3CH2−, which leads to diversity of products. The atomic‐level mechanism obtained from the well‐controlled cluster reactions provides insight into the process of selective syngas production from the photocatalytic SRM and DRM reactions over supported metal oxide catalysts.
Steam and dry reforming of methane catalyzed by gas‐phase rhodium–vanadium–oxygen cluster anions at room temperature with high syngas selectivity has been identified under photo‐irradiation conditions. The crucial step to govern syngas selectivity is the photo‐excitation of reaction intermediates such as Rh2VO3CH2− to electronically excited states that selectively produce H2 and CO.
The underlying mechanism for non‐oxidative methane aromatization remains controversial owing to the lack of experimental evidence for the formation of the first C−C bond. For the first time, the ...elementary reaction of methane with atomic clusters (FeC3−) under high‐temperature conditions to produce C−C coupling products has been characterized by mass spectrometry. With the elevation of temperature from 300 K to 610 K, the production of acetylene, the important intermediate proposed in a monofunctional mechanism of methane aromatization, was significantly enhanced, which can be well‐rationalized by quantum chemistry calculations. This study narrows the gap between gas‐phase and condensed‐phase studies on methane conversion and suggests that the monofunctional mechanism probably operates in non‐oxidative methane aromatization.
Generation of acetylene, the C−C coupling product in the high‐temperature reaction of methane with atomic cluster species (FeC3−), has been identified. This provides a molecular level origin of the monofunctional mechanism for non‐oxidative methane aromatization proposed in condensed phase systems.
Oxide‐based photoelectrodes commonly generate deep trap states associated with various intrinsic defects such as vacancies, antisites, and dislocations, limiting their photoelectrochemical ...properties. Herein, it is reported that rhombohedral GaFeO3 (GFO) thin‐film photoanodes exhibit defect‐inactive features, which manifest themselves by negligible trap‐states‐associated charge recombination losses during photoelectrochemical water splitting. Unlike conventional defect‐tolerant semiconductors, the origin of the defect‐inactivity in GFO is the strongly preferred antisite formation, suppressing the generation of other defects that act as deep traps. In addition, defect‐inactive GFO films possess really appropriate oxygen vacancy concentration for the oxygen evolution reaction (OER). As a result, the as‐prepared GFO films achieve the surface charge transfer efficiency (ηsurface) of 95.1% for photoelectrochemical water splitting at 1.23 V versus RHE without any further modification, which is the highest ηsurface reported of any pristine inorganic photoanodes. The onset potential toward the OER remarkably coincides with the flat band potential of 0.43 V versus RHE. This work not only demonstrates a new benchmark for the surface charge transfer yields of pristine metal oxides for solar water splitting but also enriches the arguments for defect tolerance and highlights the importance of rational tuning of oxygen vacancies.
Semiconductor surface commonly exhibits poor charge transfer for solar water splitting, which requires surface modification such as catalysis loading to enhance water redox kinetics. This article demonstrates that pristine rhombohedral GaFeO3 photoanodes without any further modification exhibit a record hole‐transfer efficiency for the oxygen evolution reaction at 1.23 V versus RHE.
In this work, a three-dimensional tumor-microvascular structure was simulated on a microfluidic chip for study of antioxidants effects on malignant glioma cells in vitro. The 3D hydrogel containing ...lumen was constructed to co-culture endothelial cells and glioma cells to mimic tumor microvascular environment. Macroporous gelatin transglutaminase (TG) hydrogel was prepared with biological and mechanical properties suitable for cells culture and nutrient refresh. To reform a vessel structure, U87 cells were dispersed in the TG-gelatin hydrogel and HUVEC cells were seeded in the lumen of hydrogel. Three typical antioxidants (α-lipoic acid, catechins and ascorbic acid) have been selected to research the antioxidant effects of glioma cells in the simulative tumor microenvironment. The results showed that the HUVEC cells formed vessel presented the transportation and penetrable functions for antioxidants from lumen to glioma cells. The antioxidants displayed higher selectivity to U87 cells than HUVEC cells and α-lipoic acid has a strong antioxidant capacity.
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•Simulation of a tumor-microvascular structure on microchip.•Preparation of TG hydrogel for reforming lumen and 3D cultivation.•Investigation of antioxidant effects of glioma cells under dynamic stimulation.•U87 cells presenting stronger antioxidant response than HUVEC cells.
Biomarker selection for predictive analytics encounters the problem of identifying a minimal-size subset of genes that is maximally predictive of an outcome of interest. For lung cancer gene ...expression datasets, it is a great challenge to handle the characteristics of small sample size, high dimensionality, high noise as well as the low reproducibility of important biomarkers in different studies. In this paper, our proposed meta-analysis-based regularized orthogonal matching pursuit (MA-ROMP) algorithm not only gains strength by using multiple datasets to identify important genomic biomarkers efficiently, but also keeps the selection flexible among datasets to take into account data heterogeneity through a hierarchical decomposition on regression coefficients. For a case study of lung cancer, we downloaded GSE10072, GSE19188 and GSE19804 from the GEO database with inconsistent experimental conditions, sample preparation methods, different study groups, etc. Compared with state-of-the-art methods, our method shows the highest accuracy, of up to 95.63%, with the best discriminative ability (AUC 0.9756) as well as a more than 15-fold decrease in its training time. The experimental results on both simulated data and several lung cancer gene expression datasets demonstrate that MA-ROMP is a more effective tool for biomarker selection and learning cancer prediction.
An intestine-liver-glioblastoma biomimetic system was developed to evaluate the drug combination therapy for glioblastoma. A hollow fiber (HF) was embedded into the upper layer of the microfluidic ...chip for culturing Caco-2 cells to mimic drug delivery as an artificial intestine. HepG2 cells cultured in the bottom chamber of the chip acted as an artificial liver for metabolizing the drugs. The dual-drug combination to glioblastoma U251 cells was evaluated based on the intestine-liver metabolic model. The drugs, irinotecan (CPT-11), temozolomide (TMZ) and cyclophosphamide (CP), were used to dynamically stimulate the cells by continuous infusion into the intestine unit. After intestine absorption and liver metabolism, the prodrugs were transformed to active metabolites, which induced glioblastoma cells apoptosis. The anticancer activity of the CPT-11 and TMZ combination is significantly enhanced compared to that of the single drug treatments. Combination index (CI) values of the combination groups, CPT-11 and TMZ, CPT-11 and CP, and TMZ and CP, at half maximal inhibitory concentration were 0.137, 0.288, and 0.482, respectively. The results indicated that the CPT-11 and TMZ combination was superior to the CPT-11 and CP group as well as the TMZ and CP group towards the U251 cells. The metabolism mechanism of CPT-11 and TMZ was further studied by coupling with mass spectrometric analysis. The biomimetic model enables the performance of long-term cell co-culture, drug delivery, metabolism and real-time analysis of drug effects, promising systematic in vitro mimicking of physiological and pharmacological processes.
The impact of gut microbiota and its metabolites on fat metabolism have been widely reported in human and animals. However, the critical mediators and the signal transductions are not well ...demonstrated. As ovipara, chicken represents a specific case in lipid metabolism that liver is the main site of lipid synthesis. The aim of this study is to elucidate the linkage of gut microbiota and fat synthesis in broiler chickens. The broilers were subjected to dietary treatments of combined probiotics (
Animal bifidobacterium
: 4 × 10
8
cfu/kg;
Lactobacillus plantarum
: 2 × 10
8
cfu/kg;
Enterococcus faecalis
: 2 × 10
8
cfu/kg;
Clostridium butyrate
: 2 × 10
8
cfu/kg, PB) and guar gum (1 g/kg, GG), respectively. Results showed that dietary supplementation of PB and GG changed the cecal microbiota diversity, altered short chain fatty acids (SCFAs) contents, and suppressed lipogenesis. In intestinal epithelial cells (IECs), SCFAs (acetate, propionate, and butyrate) up-regulated the expression of glucagon-like peptide-1 (GLP-1) via mitogen-activated protein kinase (MAPK) pathways, mainly via the phospho - extracellular regulated protein kinase (ERK) and phospho-p38 mitogen activated protein kinase (p38 MAPK) pathways. GLP-1 suppressed lipid accumulation in primary hepatocytes with the involvement of (AMP)-activated protein kinase/Acetyl CoA carboxylase (AMPK/ACC) signaling. In conclusion, the result suggests that SCFAs-induced GLP-1 secretion via MAPK pathway, which links the regulation of gut microbiota on hepatic lipogenesis in chickens.
Adenosine triphosphate (ATP), as the primary energy source, plays vital roles in many cellular events. Developing an efficient assay is crucial to rapidly evaluate the level of cellular ATP. A ...portable and integrated electrochemiluminescence (ECL) microsensor array based on a closed bipolar electrode (BPE) was presented. In the BPE unit, the ECL chemicals and oxidation/reduction were separated from the sensing chamber. The ATP aptamer was assembled with single-stranded DNA (ssDNA) in the sensing chamber. ATP capture made the aptamer disassemble from the ssDNA and facilitated DNA-templated silver nanocluster (Ag NC) generation by the target-rolling circle amplification (RCA) reaction. The guanine-rich padlock sequence produced tandem periodic cytosine-rich sequences by the RCA, inducing Ag NC generation in the cytosine-rich region of the produced DNA strands through Ag
reduction. The
Ag NC generation enhanced the circuit conductivity of the BPE and promoted the ECL reaction of Ru(bpy)
dppz
/tripropylamine in the anodic reservoir. On this ECL microsensor, a good linear relationship of ATP was achieved ranging from 30 to 1000 nM. The ATP content in HepG2 cells was selectively and sensitively determined without complex pretreatment. The ATP amount of 25 cells could be successfully detected when a sub-microliter sample was loaded.
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