Tumor Biomarker In-Solution Quantification, Standard Production, and Multiplex Detection

Glass Capillary-Based Nanopores for Single Molecule/Single Cell Detection

A glass capillary-based nanopore (G-nanopore), due to its tapered tip, easy tunability in orifice size, and especially its flexible surface modifications that can be tailored to effectively capture and enhance the ionic current signal of single entities (single molecules, single cells, and single particles), offers a powerful and nanoconfined sensing platform for diverse biological measurements of single cells and single molecules. Compared with other artificial two-dimensional solid-state nanopores, its conical tip and high spatial and temporal resolution characteristics facilitate noninvasive single molecule and selected area (subcellular) single cell detections (e.g., DNA mutations, highly expressed proteins, and small molecule markers that reflect the change characteristics of the tumor), as a small G-nanopore (≤100 nm) does negligible damage to cell functions and cell membrane integrity when inserted through the cell membrane. In this brief review, we summarize the preparation of G-nanopores and discuss the advantages of them as solid-state sensing platforms for single molecule and single cell detection applications as well as for cancer diagnosis and treatment applications. We also describe the current bottlenecks that limit the widespread use of G-nanopores in clinical applications and provide an outlook on future developments. The brief review will provide the reader with a quick survey of this field and facilitate the rapid development of a G-nanopore sensing platform for future tumor diagnosis and personalized medicine based on single-molecule/single-cell bioassay.

Electrochemical Genosensing of Overexpressed GAPDH Transcripts in Breast Cancer Exosomes

Exosomes are receiving highlighted attention as new biomarkers for the detection of cancer since they are profusely released by tumor cells in different biological fluids. In this paper, the exosomes are preconcentrated from the serum by immunomagnetic separation (IMS) based on a CD326 receptor as a specific epithelial cancer-related biomarker and detected by glyceraldehyde-3-phosphate dehydrogenase (GAPDH) transcripts. Following the lysis of the captured exosomes, the released GAPDH transcripts are amplified by reverse transcription polymerase chain reaction (RT-PCR) with a double-tagging set of primers on poly(dT)-modified-MPs to increase the sensitivity. The double-tagged amplicon is then quantified by electrochemical genosensing. The IMS/double-tagging RT-PCR/electrochemical genosensing approach is first demonstrated for the sensitive detection of exosomes derived from MCF7 breast cancer cells and compared with CTCs in terms of the analytical performance, showing an LOD of 4 × 102 exosomes μL-1. The genosensor was applied to human samples by immunocapturing the exosomes directly from serum from breast cancer patients and showed a higher electrochemical signal (3.3-fold, p < 0.05), when compared with healthy controls, suggesting an overexpression of GAPDH on serum-derived exosomes from breast cancer patients. The detection of GAPDH transcripts is performed from only 1.0 mL of human serum using specific magnetic particles, improving the analytical simplification and avoiding ultracentrifugation steps, demonstrating to be a promising strategy for minimal invasive liquid biopsy.

Magnetic Nanoparticle-Based Semi-automated Panning for High-Throughput Antibody Selection

Bio-panning is a common process involved in recombinant antibody selection against defined targets. The biopanning process aims to isolate specific antibodies against an antigen via affinity selection from a phage display library. In general, antigens are immobilized on solid surfaces such as polystyrene plastic, magnetic beads, and nitrocellulose. For high-throughput selection, semi-automated panning selection allows simultaneous panning against multiple target antigens adapting automated particle processing systems such as the KingFisher Flex. The system setup allows for minimal human intervention for pre- and post-panning steps such as antigen immobilization, phage rescue, and amplification. In addition, the platform is also adaptable to perform polyclonal and monoclonal ELISA for the evaluation process. This chapter will detail the protocols involved from the selection stage until the monoclonal ELISA evaluation with important notes attached at the end of this chapter for optimization and troubleshooting purposes.

Correlation between lung cancer markers and air pollutants in western China population

The relationship between serum lung cancer markers and the air pollution remains unclear. To further reveal the correlation between air pollutants and lung cancer, a retrospective analysis of 446,032 asymptomatic healthy people and symptomatic healthy people from the Health Management Center of the First Affiliated Hospital of Chongqing Medical University from 2014 to 2019 was performed. The distribution characteristics of serum lung cancer markers, cancer embryo antigens (CEA), cytokeratin 19 fragment (CYFRA211), squamous cell carcinoma antigen (SCC), and nerve-specific enolase (NSE) was analyzed in these population. Two independent sample man-Whitney U test was used to analyze the correlation of lung cancer markers and age, and a Chi-square test was used to analyze the relationship between lung cancer markers and gender. The daily change trend was profiled for six main air quality indicators PM₁₀, PM_2.5, SO₂, NO₂, CO, O₃ during the same period. The correlation between lung markers and air pollutants was investigated by Spearman and multiple linear regression. The results showed that CYFRA211 had the highest excess rate in the screening population. There were differences in the number of cases with concentrated expression of lung cancer markers in the different age groups. Among them, the people with NSE exceeding the standard were the youngest, and most of them were 40-55 years old. Besides SCC, the expression levels of other markers increased with age, and the expression levels of the four markers in males were significantly higher than those in females. Although the levels of PM₁₀ and PM_2.5 exceeded the WHO standard (World Health Organization. 2011), they were not correlated with lung cancer markers. Multiple comparisons showed that the air pollutants SO₂ and CYFRA211, as well as NO₂ and NSE were closely related, but there was no significant linear relationship between CEA, SCC, and air pollutants. In conclusion, among the four lung cancer markers, CYFRA211 had the highest abnormal excess rate in total screening population, and the expression levels of these markers varied by gender and age, with males showing significantly higher expression levels than females, and they increased significantly with age except for SCC. The differential expression of these lung cancer markers may provide more strategies for lung cancer screening in the corresponding population. Lung cancer markers, CYFRA211 and NSE, can be used as sensitive biomarkers for exposure to certain air pollutants and provide references for the prevention and management of air pollution.

The Serum Hepatitis B Virus Large Surface Protein as High-Risk Recurrence Biomarker for Hepatoma after Curative Surgery

Chronic hepatitis B (CHB) virus infection is the most important cause of HCC and is also associated with tumor progression. The development of viral biomarkers for HCC prognosis is critical in evaluating relative risks to recurrence in the CHB HCC patients. We report that the large HBV surface protein (LHBS) expression increased in the tumors, implicating that it played a significant role in tumor development. To detect the LHBS in serum and evaluate its association with HCC progression, we developed a sandwich ELISA method for LHBS. The mouse monoclonal antibodies for the pre-S1, pre-S2, and HBS regions were in-house generated and constructed into a chemiluminescent sandwich ELISA system, which allowed sensitive and quantitative measurement of the protein. Using this ELISA assay, we estimated the expression of LHBS in CHB and HCC patients. We found that the serum LHBS level was correlated with the HBS but not the viral titer in serum, indicating that HBV surface proteins’ expression does not mainly depend on viral replication. Moreover, both serum LHBS and HBS levels were lower in the HCC patients than in the CHB. The liver LHBS signals, detected by immunohistochemical staining, showed significant correlations with the serum LHBS and HBS levels. In addition, the more elevated serum LHBS but not HBS level was significantly associated with cirrhosis and worse disease-free and overall survival rates, based on the multivariate analysis. Conclusion: LHBS plays a specific role in tumor progression and is an independent parameter associated with HCC recurrence. Serum LHBS represents a novel noninvasive biomarker for HCC patients with a worse prognosis after surgery.

Spatially hierarchical nano-architecture for real time detection of Interleukin-8 cancer biomarker

In the present work we have developed two hierarchical nano-architectures based electrochemical immunosensors for the detection of interleukin-8 (IL-8) cytokine tumor biomarker. A comparative study has been performed for spatial nano-architectures and their relative sensing to establish the model for real time monitoring. With the first platform, the recognition layer consisted with immobilised IL-8 on aminothiol modified gold electrodes. In the second approach, the activated multi walled carbon nanotubes (MWCNT-COOH) were added in the functionalisation process by covalent attachment between the functionalities NH₂ of aminothiol and the functionalities COOH of carbon nanotubes. The surface topology of the recognition layer has been characterised by atomic force spectroscopy (AFM) and contact angle (CA) measurements. The electrochemical response of the developed sensor was measured by electrochemical impedance spectroscopy (EIS). A side-by-side comparison showed that aminothiol/activated MWCNTs/anti-IL-8 based impedimetric immunosensor exhibits high reproducibility (The relative standard deviation (R.S.D) = 3.2%, n = 3) with high stability. The present sensor allows evaluating a lower detection limit of 0.1 pg mL^-1 with a large dynamic sensitivity range from 1 pg mL^-1to 1000 pg mL^-1 covering the entire clinical therapeutic window. The developed MWCNTs based immunosensor has been calibrated by determining IL-8 in artificial plasma and showed a selective response to IL-8 even in the interfering environment of other cytokines such as Interleukin-1 (IL-1) and Interleukin-6 (IL-6).

Predictive value of using plasma long non-coding RNAs ANRIL and HOXA11-AS for in-stent restenosis

In-stent restenosis (ISR) can pose serious challenges for cardiologists following coronary stent implantation. Early identification of patients at high risk of ISR is considered to be effective for its prevention. However, factors that can reliably predict the risk of ISR remain elusive at present. The present study aimed to investigate the possible association between plasma long non-coding RNA (lncRNA) levels and ISR. A total of 410 patients with single-vessel lesion who received drug-eluting stents (DES) were included in the present study. After 12-36 months of follow-up, coronary angiography was performed and ISR was defined as >50% diameter stenosis at follow-up. RT-qPCR was used to measure lncRNA expression. Expression of the lncRNA RNA antisense non-coding RNA at the INK4 locus (ANRIL) was found to be upregulated whereas the lncRNA homeobox A11 antisense (HOXA11-AS) was downregulated in the plasma of patients with ISR compared with that from patients without ISR (P<0.001). Logistic regression analysis revealed that ANRIL [odds ratio (OR)=2.95; 95% confidence interval (CI)=1.68-8.08] was an independent risk factor for ISR, whilst HOXA11-AS (OR=0.58; 95% CI=0.48-0.71) was found to be an independent protective factor for ISR. Receiver operating characteristic (ROC) analysis demonstrated that high ANRIL expression [area under the ROC (auROC)=0.755; 95% CI=0.702-0.803] and low HOXA11-AS levels (auROC=0.712; 95% CI=0.657-0.763) predicted a high risk for ISR, and the combined score of ANRIL and HOXA11-AS (auROC=0.844; 95% CI=0.798-0.884) was more efficient at predicting ISR than either ANRIL or HOXA11-AS alone (P<0.001). In conclusion, increased ANRIL and decreased HOXA11-AS expressions were associated with ISR. However, combined ANRIL and HOXA11-AS plasma levels proved to be more effective at predicting ISR compared with either ANRIL or HOXA11-AS alone, suggesting that the multiplex detection of lncRNAs could be used to predict ISR in the future.