Electrochemiluminescence immunosensor for cytokeratin fragment antigen 21-1 detection using electrochemically mediated atom transfer radical polymerization

A split-type photoelectrochemical immunosensing platform based on atom-efficient cation exchange for physiological monitoring

Ultrasensitive and accurate physiological monitoring is of great significance for disease diagnosis and treatment. In this project, an efficient photoelectrochemical (PEC) split-type sensor on the basis of controlled release strategy was established with great success. Heterojunction formation between g-C₃N₄ and Zn-doped CdS improved the visible light absorption efficiency, reduced carrier complexation, improved the PEC signal, and increased the stability of the PEC platform. Compared to the traditional model of immunosensors, the process of antigen-antibody specific binding was done in a 96 microplate, and the sensor separated the immune reaction from the photoelectrochemical conversion process, eliminating mutual interference. Cu₂O nanocubes were used to label the second antibody (Ab₂), and acid etching using HNO₃ released a large amount of divalent copper ions, which exchanged cations with Cd²⁺ in the substrate material, causing a sharp drop in photocurrent and improving the sensitivity of the sensor. Under the optimized experimental conditions, the PEC sensor based on the controlled release strategy for CYFRA21-1 target detection had a wide concentration linear range of 5 × 10^-5 to 100 ng/mL with a low detection limit of 0.0167 pg/mL (S/N = 3). This intelligent response variation pattern could also offer the possibility of additional clinical applications for other target detection.

Emerging Biosensing Methods to Monitor Lung Cancer Biomarkers in Biological Samples: A Comprehensive Review

Lung cancer is the most commonly diagnosed of all cancers and one of the leading causes of cancer deaths among men and women worldwide, causing 1.5 million deaths every year. Despite developments in cancer treatment technologies and new pharmaceutical products, high mortality and morbidity remain major challenges for researchers. More than 75% of lung cancer patients are diagnosed in advanced stages, leading to poor prognosis. Lung cancer is a multistep process associated with genetic and epigenetic abnormalities. Rapid, accurate, precise, and reliable detection of lung cancer biomarkers in biological fluids is essential for risk assessment for a given individual and mortality reduction. Traditional diagnostic tools are not sensitive enough to detect and diagnose lung cancer in the early stages. Therefore, the development of novel bioanalytical methods for early-stage screening and diagnosis is extremely important. Recently, biosensors have gained tremendous attention as an alternative to conventional methods because of their robustness, high sensitivity, inexpensiveness, and easy handling and deployment in point-of-care testing. This review provides an overview of the conventional methods currently used for lung cancer screening, classification, diagnosis, and prognosis, providing updates on research and developments in biosensor technology for the detection of lung cancer biomarkers in biological samples. Finally, it comments on recent advances and potential future challenges in the field of biosensors in the context of lung cancer diagnosis and point-of-care applications.

High-bioactivity microfluidic immunosensing platform for electrochemiluminescence determination of CYFRA 21-1 with the introduction of Fe3O4@Cu@Cu2O

Relying on the electrochemiluminescence (ECL) and microfluidic technology, an immunosensor chip with high bioactivity was designed for sensitive determination of cytokeratin 19 fragment 21-1 (CYFRA 21-1). The mesoporous nanomaterial Fe₃O₄@Cu@Cu₂O as the co-reaction accelerator was used to catalyze the S₂O₈^2- to produce more SO₄^•- to achieve the amplification of the ECL signal. In fact, the generating of SO₄^•- could not only be done with the aid of the reversible cycles of Fe²⁺ and Fe³⁺ and Cu⁺ and Cu²⁺, but could be achieved also through the catalase-like function of Fe₃O₄. What is more, it has also been proved that Fe₃O₄@Cu@Cu₂O exhibited better catalytic performance than single Fe₃O₄, Cu₂O, and Cu@Cu₂O, which supported its application in this system. In addition, a portable microfluidic immunosensor chip for CYFRA 21-1-sensitive determination was assembled, which showed high selectivity, sensitivity, and strong universality in clinical cancer screening and diagnosis. It should be noted that HWRGWVC (HWR) was introduced as the antibody fixator to improve the incubation and binding efficiency of the antibody, which increased the ECL intensity and improved the sensitivity of the immunosensor. This strategy provided a new idea for cancer identification and diagnosis in clinical medicine.

The Impact of Catalpol on Proliferation, Apoptosis, Migration, and Oxidative Stress of Lung Cancer Cells Based on Nrf2/ARE Signaling

The effects of catalpol on lung cancer cell proliferation, apoptosis, migration, and oxidative stress via the Nrf2/ARE signaling pathway are investigated in this work. Catalpol-12 g/mL group, catalpol-24 g/mL group, catalpol-48 g/mL group, catalpol - 48 g/mL + vector group, catalpol - 48 g/mL + Nrf2 group, si-NC group, and si-Nrf2 group were used to split lung cancer cells A549 into control groups. Proliferation was detected using the CCK-8 assay; apoptosis was detected using flow cytometry; migration was detected using the transwell chamber; ROS was distinguished using the DCFHDA method; MDA, SOD, and GSH were detected using the microvolume method; and Cleaved Caspase-3, Cleaved Caspase-9, Nrf2, HO-1, MMP-9, and MMP-2 were detected using the Western blot method. Catalpol 12 g/mL and 24 g/mL-48 g/mL treatment decreased the proliferation activity, migration number, and Nrf2, HO-1, MMP-9, and MMP-2 protein levels of lung cancer cells when compared to the control group. SOD and GSH levels of lung cancer cells were decreased, and MDA and ROS levels were increased. Cleaved caspase-3, cleaved caspase-9 protein expression levels, and apoptosis were boosted (P < 0.05). The proliferation activity, migration number, and protein levels of Nrf2, HO-1, MMP-9, and MMP-2 in the catalpol - 48 g/mL + Nrf2 group were raised compared to the catalpol - 48 g/mL + vector group, whereas there was an apparent drop in the Cleaved Caspase-3, Cleaved Caspase-9, and apoptosis rate. Similarly, SOD and GSH contents increased, whereas MDA and ROS decreased (P < 0.05). The proliferation activity, migration number, and Nrf2, HO-1, MMP-9, and MMP-2 protein levels of lung cancer cells in the si-Nrf2 group were all decreased when compared to the si-NC and control groups. Cleaved Caspase-3 and Cleaved Caspase-9 protein expression, on the other hand, increased as MDA and ROS levels were raised while SOD and GSH levels dropped (P < 0.05). It reveals that catalpol inhibits the Nrf2/ARE signaling pathway, which causes antiproliferation, migration, apoptosis, and oxidative stress in cancer cells of lungs. The rate of apoptosis was also lowered.

Sensitive electrochemiluminescence analysis of lung cancer marker miRNA-21 based on RAFT signal amplification

An electrochemiluminescence approach based on surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) was developed for miRNA-21 detection for the first time. The SI-RAFT polymerization generates polymer chains with functional groups that are used to recruit luminol, enabling strong ECL signal output with low concentrations of miRNA-21, and greatly improving the detection sensitivity.

A Label-Free Electrochemical Immunosensor for CEA Detection on a Novel Signal Amplification Platform of Cu2S/Pd/CuO Nanocomposites

Carcinoembryonic antigen (CEA) is regarded as one of the crucial tumor markers for colorectal cancer. In this study, we developed the snowflake Cu₂S/Pd/CuO nanocomposite to construct an original label-free electrochemical immunosensor for the ultrasensitive detection of CEA levels. The nanocomposite of cuprous sulfide (Cu₂S) with Pd nanoparticles (Pd NPs) was synthesized through an in situ formation of Pd NPs on the Cu₂S. Cuprous sulfide (Cu₂S) and CuO can not only be used as a carrier to increase the reaction area but also catalyze the substrate to generate current signal. Palladium nanoparticles (Pd NPs) have excellent catalytic properties and good biocompatibility, as well as the ability of excellent electron transfer. The immunosensor was designed using 5 mmol/L H₂O₂ as the active substrate by optimizing the conditions with a detection range from 100 fg/ml to 100 ng/ml and a minimum detection limit of 33.11 fg/ml. The human serum was detected by electrochemical immunoassay, and the results were consistent with those of the commercial electrochemical immunosensor. Therefore, the electrochemical immunosensor can be used for the detection of human serum samples and have potential value for clinical application.

Liquid Biopsy-Based Biosensors for MRD Detection and Treatment Monitoring in Non-Small Cell Lung Cancer (NSCLC)

Globally, non-small cell lung cancer (NSCLC) is the leading cause of cancer deaths. Despite advancements in chemotherapy and targeted therapies, the 5-year survival rate has remained at 16% for the past forty years. Minimal residual disease (MRD) is described as the existence of either isolated tumour cells or circulating tumour cells in biological liquid of patients after removal of the primary tumour without any clinical signs of cancer. Recently, liquid biopsy has been promising as a non-invasive method of disease monitoring and treatment guidelines as an MRD marker. Liquid biopsy could be used to detect and assess earlier stages of NSCLC, post-treatment MRD, resistance to targeted therapies, immune checkpoint inhibitors (ICIs) and tumour mutational burden. MRD surveillance has been proposed as a potential marker for lung cancer relapse. Principally, biosensors provide the quantitative analysis of various materials by converting biological functions into quantifiable signals. Biosensors are usually operated to detect antibodies, enzymes, DNA, RNA, extracellular vesicles (EVs) and whole cells. Here, we present a category of biosensors based on the signal transduction method for identifying biosensor-based biomarkers in liquid biopsy specimens to monitor lung cancer treatment.