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Abstract: 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. We envision deep implications for applications not only in food safety control but also in biomedicine. [ABSTRACT FROM AUTHOR]

Abstract 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. Using this strategy, we identified one aptamer (PSA-1) that binds the glycan moiety of PSA with reasonable affinity (a dissociation constant of 177 ± 65 nM). Interestingly, an electrochemical sensor with a sandwich format employing the identified aptamer as a signaling receptor, provides a tool of discriminating human PSA from the unglycosylated protein, with a limit of detection of 0.66 ng/mL. The sensor responds to different levels of PSA in serum, correlating well with chemiluminescence ELISA used in hospitals even with higher potential to discriminate clinically meaningful prostate cancer. Although validation on a larger cohort is needed, this is the first demonstration of an aptamer-based sensor to detect PSA by focusing in its glycan moiety Highlights • A SELEX approach to direct aptamers toward de glycan structure of glycoproteins. • Aptamers recognizing the glycan moiety of prostate-specific antigen. • An aptamer-based electrochemical sandwich biosensor to detect PSA in serum. • A promising approach to aid prostate cancer diagnosis, distinguishing it from benign prostate hyperplasia. [ABSTRACT FROM AUTHOR]

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. In those raw matrices, aptamers must recognize minute amounts of biomarkers that are not unique entities but large sets of variants evolving with the disease stage. The susceptibility of aptasensors to assay conditions has driven the selection of aptamers to natural environments to ensure their optimum performance in clinical samples. We present herein a compilation of the SELEX procedures in natural milieus. By revising the electrochemical aptasensors applied to clinical samples for cancer diagnosis and tracing back to the original SELEX we analyze whether aptamers raised using these SELEX strategies are being incorporated to the diagnostic devices and how aptasensors are finding their way to a market dominated by antibody-based assays. Image 1 • Electrochemical aptasensors tested in clinical samples for cancer biomarkers. • Critical revision of aptasensors to detect CTCs, exosomes and proteins. • Relevance of natural environment during SELEX on aptamer performance. • Prospects of in-vitro diagnostic devices based on electrochemical aptasensors. [ABSTRACT FROM AUTHOR]

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. To test the clinical utility of this collagen as a cancer biomarker, specific receptors are needed. Available antibodies do not show enough selectivity or are directed toward the propeptide region that is cleaved when the protein is released to the ECM. Here we show the selection of an aptamer for the specific C-telopeptide region using a 16-mer peptide as the target for the SELEX. The aptamer selected with a K d of ∼25 nM was able to capture the collagen XI from cell lysates. It was also used for target detection in a mixed antibody-aptamer sandwich assay showing it can be useful for diagnostic purposes in biological fluids. [Display omitted] • Extracellular matrix components are an understudied source of cancer biomarkers. • Detection of collagen XI, overexpressed in some cancers, needs suitable probes. • A 16mer peptide was the target for the first aptamer for α chain of human collagen XI. • Mass spectrometry verifies collagen XI as the target of D1 aptamer from cell lysates. • Antibody-aptamer sandwich assay detects colXIα1 in cell lysates. [ABSTRACT FROM AUTHOR]