<i>Zic1</i> Promoter Hypermethylation in Plasma DNA Is a Potential Biomarker for Gastric Cancer and Intraepithelial Neoplasia

<div><p>Gastric cancer (GC) remains one of the most common digestive cancers worldwide; however, most patients present at an advanced stage at initial diagnosis. <i>Zic1</i> is a novel candidate tumor suppressor gene that is epigenetically silenced in GC. In this study, we investigated <i>Zic1</i> promoter methylation in plasma DNA as a novel molecular marker for the early diagnosis and monitoring of GC. Methylation-specific polymerase chain reaction (MSP) assay was performed to detect <i>Zic1</i> promoter methylation in plasma DNA from 20 healthy subjects, 50 gastric intraepithelial neoplasia patients, and 104 GC patients. The <i>Zic1</i> promoter methylation rate in the plasma samples from the healthy control group was 0%, but it reached 54.0% in the intraepithelial neoplasia group and 60.6% in the GC group. The latter two values were significantly higher than that found in the healthy control group (p < 0.05), with a 100% specificity for intraepithelial neoplasia and GC diagnosis. The positive predictive value of plasma <i>Zic1</i> promoter methylation for the diagnosis of intraepithelial neoplasia and GC was 100%. Methylation status in the GC group was not significantly associated with tumor size, tumor differentiation, lymph node metastasis, TNM staging, or tumor invasion (p > 0.05). Assessment of the significance of detection of the carcino-embryonic antigen (CEA) level and <i>Zic1</i> promoter methylation rate for GC diagnosis revealed that the sensitivity of <i>Zic1</i> promoter methylation was significantly higher than that of the CEA level as a marker and that the combined measurement of these two indices (parallel testing) improved sensitivity. Taken together, our results suggest that the <i>Zic1</i> promoter methylation rate in plasma-derived DNA is of great significance for the early screening of GC and monitoring of tumorigenesis. <i>Zic1</i> promoter methylation may serve as a novel non-invasive plasma biomarker for the early detection of GC and for risk assessment in high-risk populations. The combined measurement of the <i>Zic1</i> promoter methylation rate and CEA level (parallel testing) may enhance the current guidelines for the early diagnosis of GC.</p></div

Percentage of <i>Zic1</i> promoter methylation in the gastric cancer (GC), gastric intraepithelial neoplasia (GIN), early gastric cancer (ECG) and normal control (NC) groups.

<p>The percentages of <i>Zic1</i> promoter methylation were 60.6% (63/104) in the GC, 54.0% (27/50) in the GIN, 54.8% (17/31) in the EGC and 0.0% (0/20) in the NC groups (*: p < 0.001).</p

Sensitivity and specificity of markers detected in the gastric cancer (GC) group.

<p>*: <i>Zic1</i> promoter methylation combined with the CEA level (tandem testing)</p><p>/: <i>Zic1</i> promoter methylation combined with the CEA level (parallel testing)</p><p>Sensitivity and specificity of markers detected in the gastric cancer (GC) group.</p

Representative <i>Zic1</i> promoter methylation, as determined by methylation-specific polymerase chain reaction (MSP) assay.

<p>M: Methylation-specific primers; U: Unmethylated-specific primers.</p

Sensitivity and specificity of markers detected in the gastric intraepithelial neoplasia (GPI) group.

<p>*: <i>Zic1</i> promoter methylation combined with the CEA level (tandem testing)</p><p>/: <i>Zic1</i> promoter methylation combined with the CEA level (parallel testing)</p><p>Sensitivity and specificity of markers detected in the gastric intraepithelial neoplasia (GPI) group.</p

Sensitivity and specificity of markers detected in the gastric cancer (GC) group.

<p>*: <i>Zic1</i> promoter methylation combined with the CEA level (tandem testing)</p><p>/: <i>Zic1</i> promoter methylation combined with the CEA level (parallel testing)</p><p>Sensitivity and specificity of markers detected in the gastric cancer (GC) group.</p

Combined detection of <i>Zic1</i> promoter methylation and the CEA level (parallel testing) in gastric cancer (GC) plasma specimens.

<p>An ROC curve for evaluating the significance of the combined detection of the two parameters for GC diagnosis.</p

N‑Doped Graphene: An Alternative Carbon-Based Matrix for Highly Efficient Detection of Small Molecules by Negative Ion MALDI-TOF MS

Gas-phase N-doped graphene (gNG) was synthesized by a modified thermal annealing method using gaseous melamine as nitrogen source and then for the first time applied as a matrix in negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for small molecule analysis. Unlike the complicated adducts produced in positive ion mode, MS spectra obtained on gNG matrix in negative ion mode was only featured by deprotonated molecule ion peaks without matrix interference. By the gNG assisted desorption/ionization (D/I) process, some applications were carried out on a wide range of low-molecular weight (MW) analytes including amino acids, fatty acids, peptides, anabolic androgenic steroids as well as anticancer drugs, with an extraordinary laser desorption/ionization (LDI) efficiency over traditional α-cyano-4-hydroxycinnamic acid (CHCA) and other carbon-based materials in the negative ion detection mode. By comparison of a series of graphene-based matrixes, two main factors of matrix gNG were unveiled to play a decisive role in assisting negative ion D/I process: a well-ordered π-conjugated system for laser absorption and energy transfer; pyridinic-doped nitrogen species functioning as deprotonation sites for proton capture on negative ionization. The good salt tolerance and high sensitivity allowed further therapeutic monitoring of anticancer drug nilotinib in the spiked human serum, a real case of biology. Signal response was definitely obtained between 1 mM and 1 μM, meeting the demand of assessing drug level in the patient serum. This work creates a new application branch for nitrogen-doped graphene and provides an alternative solution for small molecule analysis

Intellectualized Visualization of Single-Particle Raman Spectra for Sensitive Detection and Simultaneous Multianalysis of Heavy Metal Ions

Easy-to-use, reliable, and real-time methods for detecting heavy metal ion contamination are urgently required, which is a primary concern for water pollution control and human health. However, present methods for this aim are still unable to achieve simultaneous multianalysis for complex real sample detection. Herein, an intellectualized vision-based single-nanoparticle Raman imaging strategy combined with ion-responsive functional nucleic acids (FNAs) was proposed to address these issues. We reported a correspondence between the concentration of the analytes and the density of particles (DOP) of specifically captured nanoparticles to achieve sensitive detection and simultaneous multianalysis of heavy metal ions. The specific detection of Pb2+ (Hg2+) was obtained with a detection linear range from 100 pM to 100 nM (from 500 fM to 100 nM) and limit of detections low to 1 pM (100 fM), with the advantages of good specificity, excellent homogeneity, and reproducibility. Furthermore, the differentiation of different heavy metal ions (Pb2+/Hg2+) was achieved, i.e., the simultaneous multianalysis, based on Raman imaging of the single particle and intelligent machine vision method. Finally, the Raman imaging assay was utilized for real sample analysis, and it provided a powerful and reliable tool for detecting trace Pb2+/Hg2+ in real water samples and facilitated the portable on-site monitoring of heavy metal ions

Plasmonic Probing Single-Cell Bio-Current Waves with a Shrinking Magnetite Nanoprobe

Probing of the single-cell level extracellular electron transfer highlights the maximum output current for microbial fuel cells (MFCs) at hundreds of femtoampere per cell, which is difficult to achieve by existing devices. Past studies focus on the external factors for boosting charge-extraction efficiency from bacteria. Here, we elucidate the intracellular factors that determine this output limit by monitoring the respiratory-driven shrinking kinetics of a single magnetite nanoprobe immobilized on a single Shewanella oneidensis MR-1 cell with plasmonic imaging. Quantified dissolving of nanoprobes unveils a previously undescribed bio-current fluctuation between 0 and 2.7 fA on a ∼40 min cycle. Simultaneously tracing of endogenous oscillations indicates that the bio-current waves are correlated with the periodic cellular electrokinesis. The unsynchronized electron transfer capability in the cell population results in the mean current of 0.24 fA per cell, significantly smaller than in single cells. It explains why the averaged output current of MFCs cannot reach the measured single-cell currents. This work offers a different perspective to improve the power output by extending the active episodes of the bio-current waves