Aptamer-based microchip electrophoresis assays for amplification detection of carcinoembryonic antigen

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.

Lab-on-a-chip systems for cancer biomarker diagnosis

Lab-on-a-chip (LOC) or micro total analysis system is one of the microfluidic technologies defined as the adaptation, miniaturization, integration, and automation of analytical laboratory procedures into a single instrument or "chip". In this article, we review developments over the past five years in the application of LOC biosensors for the detection of different types of cancer. Microfluidics encompasses chemistry and biotechnology skills and has revolutionized healthcare diagnosis. Superior to traditional cell culture or animal models, microfluidic technology has made it possible to reconstruct functional units of organs on chips to study human diseases such as cancer. LOCs have found numerous biomedical applications over the past five years, including integrated bioassays, cell analysis, metabolomics, drug discovery and delivery systems, tissue and organ physiology and disease modeling, and personalized medicine. This review provides an overview of the latest developments in microfluidic-based cancer research, with pros, cons, and prospects.

Current Advances in the Development of Diagnostic Tests based on Aptamers in Parasitology: A Systematic Review

Aptamers are single-stranded DNA or RNA sequences of 20–80 nucleotides that interact with different targets such as: proteins, ions, viruses, or toxins, through non-covalent interactions and their unique three-dimensional conformation. They are obtained in vitro by the systematic evolution of ligands by exponential enrichment (SELEX). Because of their ability of target recognition with high specificity and affinity, aptamers are usually compared to antibodies. However, they present many advantages that make them promising molecules for the development of new methods for the diagnosis and treatment of human diseases. In medical parasitology, aptamers also represent an attractive alternative for the implementation of new parasite detection methods, easy to apply in endemic regions. The aim of this study was to describe the current advances in the development of diagnostic tests based on aptamers in parasitology. For this, articles were selected following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with specific inclusion and exclusion criteria. The 26 resulting articles deal with the use of aptamers for the detection of six important protozoa that affect human health. This systematic review clearly demonstrates the specificity, sensitivity and selectivity of aptamers and aptasensors, that certainly will soon become standard methods in medical parasitology.

Lab-on-a-Chip Systems for Aptamer-Based Biosensing

Aptamers are oligonucleotides or peptides that are selected from a pool of random sequences that exhibit high affinity toward a specific biomolecular species of interest. Therefore, they are ideal for use as recognition elements and ligands for binding to the target. In recent years, aptamers have gained a great deal of attention in the field of biosensing as the next-generation target receptors that could potentially replace the functions of antibodies. Consequently, it is increasingly becoming popular to integrate aptamers into a variety of sensing platforms to enhance specificity and selectivity in analyte detection. Simultaneously, as the fields of lab-on-a-chip (LOC) technology, point-of-care (POC) diagnostics, and personal medicine become topics of great interest, integration of such aptamer-based sensors with LOC devices are showing promising results as evidenced by the recent growth of literature in this area. The focus of this review article is to highlight the recent progress in aptamer-based biosensor development with emphasis on the integration between aptamers and the various forms of LOC devices including microfluidic chips and paper-based microfluidics. As aptamers are extremely versatile in terms of their utilization in different detection principles, a broad range of techniques are covered including electrochemical, optical, colorimetric, and gravimetric sensing as well as surface acoustics waves and transistor-based detection.

Capillary electrophoresis-based immunoassay and aptamer assay: A review

Over the last two decades, the group of techniques called affinity probe CE has been widely used for the detection and the determination of several types of biomolecules with high sensitivity. These techniques combine the low sample consumption and high separation power of CE with the selectivity of the probe to the target molecule. The assays can be defined according to the type of probe used: CE immunoassays, with an antibody as the probe, or aptamer-based CE, with an aptamer as the probe. Immunoassays are generally divided into homogeneous and heterogeneous groups, and homogeneous variant can be further performed in competitive or noncompetitive formats. Interacting partners are free in solution at homogeneous assay, as opposed to heterogeneous analyses, where one of them is immobilized onto a solid support. Highly sensitive fluorescence, chemiluminescence or electrochemical detections were typically used in this type of study. The use of the aptamers as probes has several advantages over antibodies such as shorter generation time, higher thermal stability, lower price, and lower variability. The aptamer-based CE technique was in practice utilized for the determination of proteins in biological fluids and environmentally or clinically important small molecules. Both techniques were also transferred to microchip. This review is focused on theoretical principles of these techniques and a summary of their applications in research.

Aptamer-based biosensor for detecting carcinoembryonic antigen

Carcinoembryonic antigen (CEA), as one of the common tumor markers, is a human glycoprotein involved in cell adhesion and is expressed during human fetal development. Since the birth of human, CEA expression is largely inhibited, with only low levels in the plasma of healthy adults. Generally, CEA will overexpressed in many cancers, including gastric, breast, ovarian, lung, and pancreatic cancers, especially colorectal cancer. As one of the important tumor markers, the detection of CEA has great significance in differential diagnosis, condition monitoring and therapeutic evaluation of diseases. Conventional CEA testing typically uses immunoassay methods. However, immunoassay methods require complex and expensive instruments and professional personnel to operate. Moreover, radioactive element may cause certain damage to the human body, which limits their wide application. In the past few years, biosensors, especially aptamer-based biosensors, have attracted extensive attention due to their high sensitivity, good selectivity, high accuracy, fast response and low cost. This review briefly classifies and describes the advance in optical and electrochemical aptamer biosensors for CEA detection, also explains and compares their advantages and disadvantages.

Potential use of aptamers for diagnosis and treatment of pancreatic cancer

Pancreatic cancer (PC) is highly malignant with a low 5-year survival rate. PC currently does not have good early diagnostic markers and responses poorly to chemotherapeutic drugs. The search for better biomarkers and developing more effective chemotherapy are important ways to improve the healthcare of PC patients. Aptamers are single-stranded nucleic acids with high binding affinity and specificity to target molecules. Many aptamers against different forms of cancer including PC have been selected for both diagnostic and therapeutic use. Aptamers can work as ligands to distinguish tumour cells from normal cells. Using cells as selection targets, the obtained aptamers have been used to discover new cancer biomarkers after identification of the binding target. Aptamers have been shown to have antagonists effect on cancer cell proliferation, apoptosis, and metastasis. In addition, aptamers have been used as carriers to deliver therapeutic agents to selectively kill PC cells. This review summarises the potential use of aptamers in the diagnosis and treatment of PC.

Novel approaches for biomolecule immobilization in microscale systems

This manuscript reviews novel approaches applied for biomolecule immobilization in microscale systems.

Nucleic acid aptamers in diagnosis of colorectal cancer

Nucleic acid aptamers are promising recognition ligands for diagnostic applications. They are short DNA or RNA molecules isolated from large random libraries through the Systematic Evolution of Ligands by EXponential enrichment (SELEX) procedure. These molecules, with a particular three-dimensional shape, bind to a wide range of targets from small molecules to whole cells with high affinity and specificity. The unique properties of nucleic acid aptamers including high binding affinity and specificity, thermostability, ease of chemical production, ease of chemical modification, target adaptability, simple storage, resistance to denaturation, low immunogenicity, and low cost make them potential diagnostic tools for clinical use. Colorectal cancer is one of the most common types of cancer in humans and the third leading cause of cancer deaths in the world. Due to low response rate to current therapies in advanced stages of the disease, early detection of CRC can be useful in disease management. This review highlights recent advances in the development of nucleic acid aptamer-based methods for diagnosis, prognosis, and theranosis of colorectal cancer.

A decade of microchip electrophoresis for clinical diagnostics - A review of 2008-2017

A core element in clinical diagnostics is the data interpretation obtained through the analysis of patient samples. To obtain relevant and reliable information, a methodological approach of sample preparation, separation, and detection is required. Traditionally, these steps are performed independently and stepwise. Microchip capillary electrophoresis (MCE) can provide rapid and high-resolution separation with the capability to integrate a streamlined and complete diagnostic workflow suitable for the point-of-care setting. Whilst standard clinical diagnostics methods normally require hours to days to retrieve specific patient data, MCE can reduce the time to minutes, hastening the delivery of treatment options for the patients. This review covers the advances in MCE for disease detection from 2008 to 2017. Miniaturised diagnostic approaches that required an electrophoretic separation step prior to the detection of the biological samples are reviewed. In the two main sections, the discussion is focused on the technical set-up used to suit MCE for disease detection and on the strategies that have been applied to study various diseases. Throughout these discussions MCE is compared to other techniques to create context of the potential and challenges of MCE. A comprehensive table categorised based on the studied disease using MCE is provided. We also comment on future challenges that remain to be addressed.

Recent Microdevice-Based Aptamer Sensors

Since the systematic evolution of ligands by exponential enrichment (SELEX) method was developed, aptamers have made significant contributions as bio-recognition sensors. Microdevice systems allow for low reagent consumption, high-throughput of samples, and disposability. Due to these advantages, there has been an increasing demand to develop microfluidic-based aptasensors for analytical technique applications. This review introduces the principal concepts of aptasensors and then presents some advanced applications of microdevice-based aptasensors on several platforms. Highly sensitive detection techniques, such as electrochemical and optical detection, have been integrated into lab-on-a-chip devices and researchers have moved towards the goal of establishing point-of-care diagnoses for target analyses.

A sensitive detection method of carcinoembryonic antigen based on dsDNA-templated copper nanoparticles

A label-free fluorescence assay has been developed for the detection of carcinoembryonic antigen based on dsDNA-templated copper nanoparticles.