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Results for “SELEX Aptamer Technique”

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PubMed2026

Aptamer-Based Platforms for Human Aging Biomarkers: Multiplexed Proteomics, Biosensors and Translational Perspectives.

Aptamer-based multiplexed proteomic platforms, especially the SOMAmer-based SomaScan assay, are widely used for large-scale discovery of circulating biomarkers relevant to human aging. This review summarizes 42 original research articles published from 2020 through 2026 in which aptamers or aptamer-derived biosensors were used to characterize aging-related biomarkers in human samples or clinically relevant human-disease contexts. The eligible literature falls into several thematic areas: whole-plasma and organ-specific proteomic aging clocks; inflammaging and senescence-associated secretory phenotype (SASP) markers; cardiovascular, metabolic, renal, hepatic, musculoskeletal and neurodegenerative biomarker panels; and aptasensor platforms for detection of individual analytes. Only a small number of studies have compared aptamer- and antibody-based platforms in the same specimens; we tabulate these and show that median between-platform agreement is low to moderate, which constrains the pooling of findings across technologies. We also make explicit an interpretive point that is usually left implicit: because proteomic clocks are trained against chronological age, their correlation with chronological age measures fit to the training target rather than biological validity, and the informative quantity is the residual age gap. In the reviewed literature, SomaScan-based studies are concentrated in cardiovascular, neurodegenerative, frailty, and proteomic aging-clock research, whereas de novo SELEX campaigns targeting aging-specific epitopes and longitudinal human validation of wearable aptasensors were not identified. The main barriers to translation are cross-platform discordance, limited replication across ancestries, under-reported pre-analytical variability, cost, and the research-use-only status of most assays.

Humans↗

PubMed2006

Anti-Francisella tularensis DNA aptamers detect tularemia antigen from different subspecies by Aptamer-Linked Immobilized Sorbent Assay.

Aptamers are powerful candidates for molecular detection of targets due to their unique recognition properties. These affinity probes can be used to recognize and bind to their targets in the various types of assays that are currently used to detect and capture molecules of interest. They are short single-stranded (ss) oligonucleotides composed of DNA or RNA sequences that are selected in vitro based on their affinity and specificity for the target. Using combinatorial oligonucleotide libraries, we have selected ssDNA aptamers that bind to Francisella tularensis subspecies (subsp) japonica bacterial antigen. F. tularensis is an intracellular, nonmotile, nonsporulating, Gram-negative bacterial pathogen that causes tularemia in man and animals. Just as antibodies have been used to detect specific targets in varying formats, it is possible that nucleic acid-binding species or aptamers could be used to specifically detect biomolecules. Aptamers offer advantages over antibody-based affinity molecules in production, regeneration and stability due to their unique chemical properties. We have successfully isolated a set of 25 unique DNA sequences that specifically bind to F. tularensis subspecies japonica. When tested in a sandwich Aptamer-Linked Immobilized Sorbent Assay (ALISA) and dot blot analysis, the aptamer cocktail exhibited specificity in its ability to bind only to tularemia bacterial antigen from subspecies japonica, holarctica (also known as palaearctica) and tularensis but not to Bartonella henselae. Moreover, there is no binding observed either to pure chicken albumin or chicken lysozyme. Thus, it appears that this novel antitularemia aptamer cocktail may find application as a detection reagent for a potential biological warfare agent like F. tularensis.

Antigens, Bacterial↗

PubMed2005

DNA and RNA aptamers as modulators of protein function.

The SELEX technique (systematic evolution of ligands by exponential enrichment) is a combinatorial library approach in which DNA or RNA molecules are selected by their ability to bind their protein targets with high affinity and specificity. The isolated molecules are referred to as aptamers (from aptus = Latin "to fit"). First, RNA and DNA aptamers were identified that bind to proteins naturally interacting with nucleic acids, or to small organic molecules such as ATP. In the following years, the use of the SELEX technique was extended to isolate oligonucleotide ligands for a wide range of proteins of importance for therapy, and diagnostics. Since these RNA and DNA molecules bind their targets with similar affinities as antibodies, and are able to distinguish between isotypes of an enzyme, aptamers have been also called synthetic antibodies. Recently, the use of in vitro selection methods to isolate protein inhibitors has been extended to complex targets, such as receptors that are only functional in their membrane-bound form, cells, and trypanosomes. RNA aptamers have been expressed in living cells where they inhibit a protein implicated in intracellular signal transduction. The utility of aptamers for in vivo experiments, and diagnostic and therapeutic purposes, is considerably enhanced by introducing chemical modifications into the oligonucleotides to provide resistance against enzymatic degradation in body fluids. Recently, such inhibitors have been evolved for a great variety of targets, including receptors, growth factors, and adhesion molecules implicated in disease. Furthermore, some results were already obtained in animal models and clinical trials.

Animals↗

PubMed2006

[Current reviews in aptamers].

Aptamers are oligo-nucleotides which are selected by SELEX (systematic evolution of ligands by exponential enrichment) in vitro, it can bind protein or other small molecules with high specificity and affinity. Researches on aptamers have achieved much progress in biosensor, drug development and nano technology. This article has reviewed the researches and applications of aptamers in the past two years.

Animals↗

PubMed2005

Screening of DNA aptamers against multiple proteins in tissue.

We report the development of a novel screening method for DNA aptamers against multiple proteins in the target tissue. Although a purified single protein is generally used in screening of aptamers at present, such a simultaneous selection would be very advantageous in efficiency and selectivity. We first carried out the screening in situ and it was suggested that aptamers against particular target proteins were enriched. We also developed another novel screening method named Aptamer Blotting based on protein separation by PAGE and its visualization with fluorescein labeled aptamers and it was demonstrated that this method allowed the simultaneous selection of specific aptamers against multiple proteins.

Animals↗

PubMed2006

DNA and RNA aptamers: from tools for basic research towards therapeutic applications.

The systematic evolution of ligands by exponential enrichment (SELEX) is a combinatorial oligonucleotide library-based in vitro selection approach in which DNA or RNA molecules are selected by their ability to bind their targets with high affinity and specificity, comparable to those of antibodies. Nucleic acids with high affinity for their targets have been selected against a wide variety of compounds, from small molecules, such as ATP, to membrane proteins and even whole organisms. Recently, the use of the SELEX technique was extended to isolate oligonucleotide ligands, also known as aptamers, for a wide range of proteins of importance for therapy and diagnostics, such as growth factors and cell surface antigens. The number of aptamers generated as inhibitors of various target proteins has increased following automatization of the SELEX process. Their diagnostic and therapeutic efficacy can be enhanced by introducing chemical modifications into the oligonucleotides to provide resistance against enzymatic degradation in body fluids. Several aptamers are currently being tested in preclinical and clinical trials, and aptamers are in the process of becoming a new class of therapeutic agents. Recently, the anti-VEGF aptamer pegaptanib received FDA approval for treatment of human ocular vascular disease.

Aptamers, Nucleotide↗

PubMed2006

In vitro selection of DNA aptamer against abrin toxin and aptamer-based abrin direct detection.

Abrin toxin as the target protein, belongs to class II ribosome-inactivating proteins family, has high toxicity to eukaryotic cells. Here, we firstly report the DNA aptamers, isolated by in vitro selection, recognize abrin toxin with high affinity and specificity, and have the advantage of no cross-reaction with structure-similar protein ricin toxin over antibodies. Then, a highly selective and sensitive aptamer-based abrin assay was established using a molecular light switching reagent [Ru(phen)(2)(dppz)](2+) with a limit of detection of 1 nM and a wide linear range from 1 to 400 nM with the correlation coefficient of 0.993. This assay can be successfully directly performed not only in physiological buffer but also in more complicated biological matrix, such as diluted serum.

Abrin↗

PubMed2006

[Aptamers: selection and scope of applications].

Aptamers are short oligonucleotides selected from large combinatorial pools of sequences for their capacity to bind to many different targets ranging from small molecules (amino acids, antibiotics...) to proteins or nucleic acid structures. Aptamers present the same high specificity and affinity for their targets as antibodies. In addition to efficient binding, aptamers have been shown in many cases to display an inhibitory activity against their targets. Many aptamers are now being developed against biomedical relevant targets, and one aptamer that inhibits the human VEGF165 already received approval for the treatment of age-related macular degeneration. Here we discuss the principles and the practical way of selecting aptamers (SELEX technology) as well as the structural basis for their performance as ligands. A wide scope of applications is described - aptamers have been used as tools for studying nucleic acids/proteins interactions, detecting, purifying or imaging target molecules, regulating gene expression - and includes recent developments of aptamers for therapy and diagnosis.

Combinatorial Chemistry Techniques↗

PubMed2004

In vitro selection of high-affinity DNA ligands for human IgE using capillary electrophoresis.

Aptamers with high affinity for IgE were selected using capillary electrophoresis to demonstrate the compatibility of this technique with SELEX. The high selectivity and efficiency of CE gave rise to a very high rate of enrichment, allowing high-affinity, high-selectivity aptamers to be obtained in only four rounds of selection. Decreasing the number of rounds shortens the selection procedure from the 4-6 weeks typical of SELEX to several days. The use of "bulk" dissociation constant measurements was introduced as a method for assessing the DNA pool after each round of selection. The average dissociation constant of the sequences in the DNA pool for IgE after four rounds of selection was 29 nM. The distribution of the dissociation constants for the sequences in the pool was very narrow with a standard deviation of only 6 nM. All of the sequences assessed exhibited high specificity for human IgE when compared with human IgG or mouse IgE.

Animals↗

PubMed2006

Nonantibody-based recognition: alternative molecules for detection of pathogens.

Immunoassays have been well established for many years as the cornerstone of detection technologies. These assays are sensitive, selective and, in general, highly resistant to interference from complex sample matrices when compared with nucleic acid-based tests. However, both antibody- and nucleic acid-based detection systems require a priori knowledge of the target and development of specific reagents; multiplexed assays can become increasingly problematic when attempting to detect a plethora of different targets, the identities of which are unknown. In an effort to circumvent many of the limitations inherent in these conventional assays, other recognition reagents are being explored as alternatives, or indeed as adjuncts, to antibodies for pathogen and toxin detection. This article will review a number of different recognition systems ranging in complexity from small molecules, such as nucleic-acid aptamers, carbohydrates and peptides, to systems as highly complicated as whole cells and organisms. All of these alternative systems have tremendous potential to achieve superior sensitivity, selectivity, and stability, but are also subject to their own limitations, which are also discussed. In short, while in its infancy, this field holds great promise for the development of rapid, fieldable assays that are highly complementary to existing antibody- and nucleic acid-based technologies.

Bacteria↗

PubMed2007

Nucleic acid-based aptamers as promising therapeutics in neoplastic diseases.

Isolated through combinatorial libraries by an iterative in vitro selection process, small single-stranded nucleic acid compounds, named aptamers, have been developed as high-affinity ligands for a variety of targets, ranging from small chemical compounds to large proteins. In the last years, an increasing number of aptamers has been generated that represent potential antagonists of the disease-associated target proteins. These molecules have been shown to discriminate between even closely related targets, thus representing a valid alternative to antibodies or other biomimetic receptors for the development of biosensors and other bioanalytical methods. Moreover, they can be easily stabilized by chemical modifications for in vivo applications and numerous examples have shown that stabilized aptamers against extracellular targets such as growth factors, receptors, hormones, or coagulation factors are very effective inhibitors of the corresponding protein function, thus resulting as useful reagents for target validation in a variety of diseases, including cancer. Indeed, many signaling proteins involved in diverse functions such as cell growth and differentiation can act as oncogenes and cause cellular transformation, thus making these high affinity ligands promising tools for cancer diagnosis or therapy.

Animals↗

PubMed2005

Capillary electrophoresis-SELEX selection of aptamers with affinity for HIV-1 reverse transcriptase.

Capillary electrophoresis-SELEX (CE-SELEX) was used to select ssDNA aptamers with affinity for HIV reverse transcriptase (HIVRT). A library of ssDNA was incubated with HIVRT. Sequences bound to HIVRT were isolated using CE, PCR amplified, and purified, yielding an enriched ssDNA pool suitable for further rounds of selection. Aptamers with dissociation constants as low as 180 pM were isolated after four rounds of selection. This is the first report of aptamers isolated by CE-SELEX with higher affinity than those obtained for the same target using conventional selection techniques. No sequence motifs were identified in the 27 clones sequenced, suggesting that there are many sequences that can bind HIVRT with low picomolar dissociation constants.

Aptamers, Nucleotide↗

PubMed2005

Nucleic acid-based fluorescence sensors for detecting proteins.

We report here development of a rapid, homogeneous, aptamer-based fluorescence assay ("molecular beacons") for detecting proteins. The assay involves protein-induced coassociation of two aptamers recognizing two distinct epitopes of the protein. The aptamers contain short fluorophore-labeled complementary "signaling" oligonucleotides attached to the aptamer by non-DNA linker. Coassociation of the two aptamers with the protein results in bringing the two "signaling" oligonucleotides into proximity, producing a large change of fluorescence resonance energy transfer between the fluorophores. We used thrombin as a model system to provide proof-of-principle evidence validating this molecular beacon design. Thrombin beacon was capable of detecting the protein with high selectivity (also in complex biological mixtures), picomolar sensitivity, and high signal-to-background ratio. This is a homogeneous assay requiring no sample manipulation. Since the design of molecular beacons described here is not limited to any specific protein, it will be possible to develop these beacons to detect a variety of target proteins of biomedical importance.

Biosensing Techniques↗

PubMed2006

Methods developed for SELEX.

SELEX (systematic evolution of ligands by exponential enrichment) is a process that involves the progressive purification from a combinatorial library of nucleic acid ligands with a high affinity for a particular target by repeated rounds of partitioning and amplification. With the development of aptamer technology over the last decade, various modified SELEX processes have arisen that allow various aptamers to be developed against a wide variety of molecules, irrespective of the target size. In the present review, the separation methods used in such SELEX processes are reviewed.

Aptamers, Nucleotide↗

PubMed2006

CUG-BP1/CELF1 requires UGU-rich sequences for high-affinity binding.

CUG-BP1 [CUG-binding protein 1 also called CELF (CUG-BP1 and ETR3 like factors) 1] is a human RNA-binding protein that has been implicated in the control of splicing and mRNA translation. The Xenopus homologue [EDEN-BP (embryo deadenylation element-binding protein)] is required for rapid deadenylation of certain maternal mRNAs just after fertilization. A variety of sequence elements have been described as target sites for these two proteins but their binding specificity is still controversial. Using a SELEX (systematic evolution of ligand by exponential enrichment) procedure and recombinant CUG-BP1 we selected two families of aptamers. Surface plasmon resonance and electrophoretic mobility-shift assays showed that these two families differed in their ability to bind CUG-BP1. Furthermore, the selected high-affinity aptamers form two complexes with CUG-BP1 in electrophoretic mobility assays whereas those that bind with low affinity only form one complex. The validity of the distinction between the two families of aptamers was confirmed by a functional in vivo deadenylation assay. Only those aptamers that bound CUG-BP1 with high affinity conferred deadenylation on a reporter mRNA. These high-affinity RNAs are characterized by a richness in UGU motifs. Using these binding site characteristics we identified the Xenopus maternal mRNA encoding the MAPK (mitogen-activated protein kinase) phosphatase (XCl100alpha) as a substrate for EDEN-BP. In conclusion, high-affinity CUG-BP1 binding sites are sequence elements at least 30 nucleotides in length that are enriched in combinations of U and G nucleotides and contain at least 4 UGU trinucleotide motifs. Such sequence elements are functionally competent to target an RNA for deadenylation in vivo.

3' Untranslated Regions↗

PubMed2006

[Aptamers in clinical diagnostics].

Aptamers are single-stranded DNA or RNA oligonucleotides selected in vitro from combinatorial libraries in a process called SELEX (Systematic Evolution of Ligands by EXponential Enrichment). Aptamers play a role of artificial nucleic acid ligands that can recognize and bind to various organic or inorganic target molecules with high specificity and affinity. They can discriminate even between closely related targets and can be easily chemically modified for radioactive, fluorescent and enzymatic labeling or biostability improvement. Aptamers can thus be considered as universal receptors that rival antibodies in diagnostics as a tool of molecular recognition. To date aptamers have been successively used instead of monoclonal antibodies in flow cytometry, immunochemical sandwich assays and in vivo imaging as well to detect wide range of small or large biomolecules.

Aptamers, Nucleotide↗

PubMed2006

Nucleic acid-functionalized Pt nanoparticles: Catalytic labels for the amplified electrochemical detection of biomolecules.

Nucleic acid-functionalized Pt nanoparticles (Pt-NPs) act as catalytic labels for the amplified electrochemical detection of DNA hybridization and aptamer/protein recognition. Hybridization of the nucleic acid-modified Pt-NPs with a sensing nucleic acid/analyte DNA complex associated with an electrode enables the amperometric, amplified, detection of the DNA by the Pt NP electrocatalyzed reduction of H2O2 (sensitivity limit, 1 x 10(-11) M). Similarly, the association of aptamer-functionalized Pt- NPs to a thrombin aptamer/thrombin complex associated with an electrode allowed the amplified, electrocatalytic detection of thrombin with a sensitivity limit corresponding to 1 x 10(-9) M.

Aptamers, Nucleotide↗

PubMed2006

RNA aptamers selectively modulate protein recruitment to the cytoplasmic domain of beta-secretase BACE1 in vitro.

The beta-amyloid peptide (Abeta) is a major component of the Alzheimer's disease (AD)-associated senile plaques and is generated by sequential cleavage of the beta-amyloid precursor protein (APP) by beta-secretase and gamma-secretase. Since BACE1 initiates Abeta generation it represents a valuable target to interfere with Abeta production and treatment of AD. While the enzymatic activity of BACE1 resides in the extracellular domain, the protein also contains a short cytoplasmic tail (B1-CT). This domain serves as a binding site for at least two proteins, the copper chaperone for superoxide dismutase-1 (CCS), and the Golgi-localized, gamma-ear-containing, ADP ribosylation factor-binding (GGA1) protein, and contains a single phosphorylation site. However, the precise role of the B1-CT for the overall biological function of this protein is largely unknown. Functional studies focusing on the activity of this domain would strongly benefit from the availability of domain-specific inhibitors. Here we describe the isolation and characterization of RNA aptamers that selectively target the B1-CT. We show that these RNAs bind to authentic BACE1 and provide evidence that the binding site is restricted to the membrane-proximal half of the C terminus. Aptamer-binding specifically interferes with the recruitment of CCS, but still permits GGA1 association and casein kinase-dependent phosphorylation, consistent with selective binding site targeting within this short peptide. Because phosphorylation and GGA1 binding to B1-CT regulate BACE1 transport, these RNA inhibitors could be applied to investigate B1-CT activity without affecting the subcellular localization of BACE1.

ADP-Ribosylation Factors↗