A review on magnetic beads-based SELEX technologies: Applications from small to large target molecules.

This review summarizes the stepwise strategy and key points for magnetic beads (MBs)-based aptamer selection which is suitable for isolating aptamers against small and large molecules via systematic evolution of ligands by exponential enrichment (SELEX). Particularities, if any, are discussed according to the target size. Examples targeting small molecules (<1000 Da) such as xenobiotics, toxins, pesticides, herbicides, illegal additives, hormones, and large targets such as proteins (biomarkers, pathogens) are discussed and presented in tabular formats.

Lectin-Mimicking Aptamer as a Generic Glycan Receptor for Sensitive Detection of Glycoproteins Associated with Cancer.

The shortage of specific glycan recognition reagents has proven a significant hurdle in the development of assays to detect altered glycoforms associated with cancer. Here, a carbohydrate-binding aptamer originally selected against the glycan moiety of prostate-specific antigen (PSA) is used as a lectin-mimicking reagent. As a first proof-of-principle, this aptamer has been applied to develop a sandwich-type electrochemical biosensor for the detection of the serum amyloid P (SAP) component, a glycosylated protein whose increased sialylation has been associated with pancreatic cancer.

Capacitive spectroscopy as transduction mechanism for wearable biosensors: opportunities and challenges.

Wearable sensors would revolutionize healthcare and personalized medicine by providing individuals with continuous and real-time data about their bodies and environments. Their integration into everyday life has the potential to enhance well-being, improve healthcare outcomes, and offer new opportunities for research. Capacitive sensors technology has great potential to enrich wearable devices, extending their use to more accurate physiological indicators.

Comparing nanobody and aptamer-based capacitive sensing for detection of interleukin-6 (IL-6) at physiologically relevant levels.

A major societal challenge is the development of the necessary tools for early diagnosis of diseases such as cancer and sepsis. Consequently, there is a concerted push to develop low-cost and non-invasive methods of analysis with high sensitivity and selectivity. A notable trend is the development of highly sensitive methods that are not only amenable for point-of-care (POC) testing, but also for wearable devices allowing continuous monitoring of biomarkers.

First bioelectronic immunoplatform for quantitative secretomic analysis of total and metastasis-driven glycosylated haptoglobin.

The glycosylation status of proteins is increasingly used as biomarker to improve the reliability in the diagnosis and prognosis of diseases as relevant as cancer. This feeds the need for tools that allow its simple and reliable analysis and are compatible with applicability in the clinic. With this objective in mind, this work reports the first bioelectronic immunoplatforms described to date for the determination of glycosylated haptoglobin (Hp) and the simultaneous determination of total and glycosylated Hp.

A competitive assay for the detection of a 16-mer peptide from α1 chain of human collagen XI.

Characterization of extracellular matrix (ECM) is becoming more and more important to decipher cancer progression. Constant remodeling results in ECM components degradation or unusual ECM accumulation that releases short fragments to the body fluids. These fragments might be potential cancer biomarkers but to detect them specific receptors are needed.

Aptamers targeting a tumor-associated extracellular matrix component: The human mature collagen XIα1.

The extracellular matrix (ECM) plays an essential role in tumor progression and invasion through its continuous remodeling. The growth of most carcinomas is associated with an excessive collagen deposition that provides the proper environment for tumor development and chemoresistance. The α1 chain of a minor human collagen, type XI, is overexpressed in some tumor stroma, but not found in normal stroma.

Dual electrochemical genosensor for early diagnosis of prostate cancer through lncRNAs detection.

The prostate specific antigen (PSA) test is the gold standard for the screening of prostate cancer (PCa), despite its limited clinical specificity. Long noncoding RNAs are released from the tumor tissue to the urine and show great potential for improving specificity in PCa diagnosis. This work reports on a sandwich-type hybridization assay to detect both the urinary biomarker prostate cancer antigen 3 (PCA3) and an endogenous control, the PSA mRNA.

Aptamers targeting protein-specific glycosylation in tumor biomarkers: general selection, characterization and structural modeling.

Detecting specific protein glycoforms is attracting particular attention due to its potential to improve the performance of current cancer biomarkers. Although natural receptors such as lectins and antibodies have served as powerful tools for the detection of protein-bound glycans, the development of effective receptors able to integrate in the recognition both the glycan and peptide moieties is still challenging. Here we report a method for selecting aptamers toward the glycosylation site of a protein.

Bioanalytical methods for circulating extracellular matrix-related proteins: new opportunities in cancer diagnosis.

The role of the extracellular matrix (ECM) remodeling in tumorigenesis and metastasis is becoming increasingly clear. Cancer development requires that tumor cells recruit a tumor microenvironment permissive for further tumor growth. This is a dynamic process that takes place by a cross-talk between tumor cells and ECM.

Impedimetric aptamer-based glycan PSA score for discrimination of prostate cancer from other prostate diseases.

Prostate specific antigen (PSA) is the common biomarker for prostate cancer (PCa). However, its lack of specificity to differentiate PCa from benign prostate disorders stimulates the search for alternative cancer biomarkers to improve the clinical management of the patients. Different studies have described changes in the core-fucosylation level of PSA between PCa patients and healthy controls.

New Uses for the Personal Glucose Meter: Detection of Nucleic Acid Biomarkers for Prostate Cancer Screening.

A personal glucose meter (PGM)-based method for quantitative detection of a urinary nucleic acid biomarker in prostate cancer screening, the so-called PCA3, is reported herein. A sandwich-type genoassay is conducted on magnetic beads to collect the target from the sample by specific hybridization, making the assay appropriate for PCA3 detection in biological fluids. The success of the method hinges on the use of alkaline phosphatase (ALP) to link the amount of nucleic acid biomarker to the generation of glucose.

Truncated aptamers as selective receptors in a gluten sensor supporting direct measurement in a deep eutectic solvent.

Enzyme-linked immunosorbent assays are currently the most popular methods to quantify gluten in foods. Unfortunately, the antibodies used as specific receptors in such methods are not compatible with the usual solvents for the extraction of gluten proteins. In consequence, commercial tests require a high dilution of the sample after the extraction, increasing the limit of quantification and decreasing convenience.

Electrochemical aptasensors for cancer diagnosis in biological fluids - A review.

The tunability of SELEX procedure is an essential feature to supply bioaffinity receptors (aptamers) almost on demand for analytical and therapeutic purposes. This longstanding ambition is, however, not straightforward. Non-invasive cancer diagnosis, so called liquid biopsy, requires collection of body fluids with minimal or no sample pretreatment.

On the Electrochemical Detection of Alpha-Fetoprotein Using Aptamers: DNA Isothermal Amplification Strategies to Improve the Performance of Weak Aptamers.

Affinity characterization is essential to develop reliable aptamers for tumor biomarker detection. For alpha-fetoprotein (AFP), a biomarker of hepatocellular carcinoma (HCC), two DNA aptamers were described with very different affinity. In this work, we estimate the dissociation constant of both of them by means of a direct assay on magnetic beads modified with AFP and electrochemical detection on carbon screen-printed electrodes (SPCE).

The Translational Potential of Electrochemical DNA-Based Liquid Biopsy.

Latest technological advancement has tremendously expanded the knowledge on the composition of body fluids and the cancer-associated changes, which has fueled the replacement of invasive biopsies with liquid biopsies by using appropriate specific receptors. DNA emerges as a versatile analytical reagent in electrochemical devices for hybridization-based or aptamer-based recognition of all kind of biomarkers. In this mini review, we briefly introduce the current affordable targets (tumor-derived nucleic acids, circulating tumor cells and exosomes) in body fluids, and then we provide an overview of selected electrochemical methods already applied in clinical samples by dividing them into three large categories according to sample type: red (blood), yellow (urine), and white (saliva and sweat) diagnostics.

A convenient renewable surface plasmon resonance chip for relative quantification of genetically modified soybean in food and feed.

The cultivation of genetically modified organisms (GMO) continues to expand worldwide. Still, many consumers express concerns about the use of GMO in food or feed, and many countries have legislated on labelling systems to indicate the presence of GMO in commercial products. To deal with the increased number of GMO events and to address related regulations, alternative detection methods for GMO inspection are required.

FeO@Au nanoparticles-based magnetoplatform for the HMGA maize endogenous gene electrochemical genosensing.

This work addresses a technological advance applied to the construction of a magnetogenoassay with electrochemical transduction for the maize taxon-specific (HMGA gene) detection using gold-coated magnetic nanoparticles as nanosized platform. Superparamagnetic core-shell FeO@Au nanoparticles (10.4 ± 1.

Unravelling the lipocalin 2 interaction with aptamers: May rolling circle amplification improve their functional affinity?

Cancer diagnosis based on serum biomarkers requires receptors of extreme sensitivity and selectivity. Tunability of aptamer selection makes them ideal for that challenge. However, aptamer characterization is a time-consuming task, not always thoroughly addressed, leading to suboptimal aptamer performance.

Long noncoding RNAs: from genomic junk to rising stars in the early detection of cancer.

Despite having been underappreciated in favor of their protein-coding counterparts for a long time, long noncoding RNAs (lncRNAs) have emerged as functional molecules, which defy the central dogma of molecular biology, with clear implications in cancer. Altered expression levels of some of these large transcripts in human body fluids have been related to different cancer conditions that turns them into potential noninvasive cancer biomarkers. In this review, a brief discussion about the importance and current challenges in the determination of lncRNAs associated to cancer is provided.

Focusing aptamer selection on the glycan structure of prostate-specific antigen: Toward more specific detection of prostate cancer.

The development of chemical sensors capable of detecting the specific glycosylation patterns of proteins offers a powerful mean for the early detection of cancer. Unfortunately, this strategy is scarcely explored because receptors recognizing the glycans linked to proteins are challenging to discover. In this work, we describe a simple method for directing the selection of aptamers toward the glycan structure of the glycoproteins, with prostate-specific antigen (PSA) as a model target.

Selection of Anti-gluten DNA Aptamers in a Deep Eutectic Solvent.

Herein, we show the feasibility of using deep eutectic solvents as a faster way of selecting aptamers targeting poorly water-soluble species. This unexplored concept is illustrated for gluten proteins. In this way, aptamer-based gluten detection can be performed directly in the extraction media with improved detectability.

Trapping -Quinone Methide Intermediates with Ferrocene: Synthesis and Preliminary Biological Evaluation of New Phenol-Ferrocene Conjugates.

The reaction of -hydroxybenzyl alcohols with ferrocene in the presence of a catalytic amount of InCl₃ provided ferrocenyl phenol derivatives, an interesting class of organometallic compounds with potential applications in medicinal chemistry. This transformation exhibited a reasonable substrate scope delivering the desired products in synthetically useful yields. Evidence of involvement of a -quinone methide intermediate in this coupling process was also provided.

Electrochemical genoassays on gold-coated magnetic nanoparticles to quantify genetically modified organisms (GMOs) in food and feed as GMO percentage.

The integration of nanomaterials in the field of (bio)sensors has allowed developing strategies with improved analytical performance. In this work, ultrasmall core-shell FeO@Au magnetic nanoparticles (MNPs) were used as the platform for the immobilization of event-specific Roundup Ready (RR) soybean and taxon-specific DNA sequences. Firstly, monodisperse FeO MNPs were synthesized by thermal decomposition and subsequently coated with a gold shell through reduction of Au(III) precursor on the surface of the MNPs in the presence of an organic capping agent.