Search Results (1,923)

Pseudomonas aeruginosa is an important waterborne pathogen that is harmful to food safety and human health. Therefore, the detection of Pseudomonas aeruginosa has become an essential item in food sampling. This article constructs a fluorescent aptamer sensor based on Tb-MOFs, using Tb-MOFs as the fluorescence signal source, colloidal gold (AuNPs) as the signal conversion switch, and aptamers as the target recognition element, to establish a quantitative detection method for Pseudomonas aeruginosa. The constructed sensor exhibits a good linear relationship within the concentration range of Pseudomonas aeruginosa from 1 to 10⁶ CFU/mL, with a detection limit of 0.63 CFU/mL. Moreover, the sensor was also applied to the detection of Pseudomonas aeruginosa in actual samples of bottled drinking water and orange juice. The fluorescent aptasensor based on Tb-MOFs provides a rapid and sensitive new sensing method for the detection of Pseudomonas aeruginosa in food. Full article

Therapeutics based on RNA are commonly produced via biocatalytic approaches using RNA polymerases. The most frequently applied enzyme is the RNA polymerase of Enterobacteria phage T7. However, this enzyme has unfavorable properties, like the formation of double-stranded RNA (dsRNA). This undesired by-product can activate the innate immune system via pattern recognition receptors and cause inflammation. Removal of the contaminant is time-consuming and expensive. In this work, we applied a genome mining approach to identify unidentified single-subunit RNA polymerases with minimal dsRNA generation. A large meta database was screened, and 74 sequences were selected. Two RNA polymerases generating barely detectable amounts of dsRNA were identified from the initial sequence portfolio. Their promoters were detected via a fluorescent RNA aptamer screening, and slightly acidic transcription conditions were established. Further activity characterization showed a significant reduction of dsRNA to 0.001% and 0.02%. Due to these beneficial attributes, these RNA polymerases generate mRNA with enhanced stability, which most likely lowers the immune response towards the desired mRNA. This could be especially useful for producing long RNAs, such as self-amplifying RNA, as these typically require improved stability and low dsRNA content. Full article

Background/Objectives: Leishmaniasis is a disease affecting millions of people caused by parasites of the genus Leishmania. The GP63 protein of Leishmania infantum (LiGP63) is one of its major surface antigens and a main virulence factor, playing a role in the adhesion of extracellular promastigote stages to macrophages and in the survival of intracellular amastigotes. Methods: Here, DNA aptamers have been developed against LiGP63 through the systematic evolution of ligands by exponential enrichment. Results: Twenty individual aptamer sequences were characterized using confocal fluorescence microscopy and flow cytometry analysis, and 14 of them had targeting to more than 70% of L. infantum promastigotes with different subcellular localization patterns. Subsequent dot blot analyses narrowed down the selection to five candidates for further characterization through an aptamer-linked immobilized sorbent assay where it was possible to detect endogenous LiGP63 in L. infantum promastigote lysates. The five selected aptamers recognized the recombinant LiGP63 protein with binding affinities ranging from 0.3 to 2.1 µM. Promastigotes preincubated with LiGP63Apt-4, -27 and -28 exhibited a significantly reduced adhesion to and infection of RAW 264.7 macrophages. Moreover, when LiGP63Apt-4 and -28 were conjugated to liposomes, these two aptamers significantly enhanced the targeting to L. infantum promastigotes compared to plain liposomes. Conclusions: Given their improved stability and cost-effectiveness over antibodies, the aptamers evolved here represent promising candidates for new therapeutic and diagnostic approaches and for future nanoparticle-based drug delivery strategies in leishmaniasis. Full article

Background: This study aimed to develop a superior aptamer-based therapeutic for targeted glioblastoma intervention by conducting a comparative analysis of two DNA aptamers: the original U2 sequence, selected against glioblastoma cells exhibiting high EGFRvIII expression, and its modified, shortened, and stabilized variant, Gol1. Methods: The effects of the investigated aptamers on primary human glioblastoma cells with graded receptor expression levels and on a rat 101/8 glioblastoma tissue model were rigorously studied. Results: The results demonstrated the significant superiority of the stabilized Gol1 aptamer, which exhibited exceptional binding affinity for the EGFRvIII receptor. Pronounced antiproliferative and antimigratory effects against EGFRvIII-positive human tumor cells, ultimately inducing complete cell death. Transcriptomic analysis revealed a sophisticated dual mechanism of action for Gol1: the specific activation of neuronal differentiation genes concurrent with the suppression of key alternative splicing factors. Crucially, in vivo confirmation showed highly selective accumulation of the FAM-labeled Gol1 aptamer exclusively within tumor tissue, with a maximum concentration gradient observed in the invasive border zone and a complete absence of accumulation in intact brain parenchyma. Conclusions: These comprehensive findings confirm that the Gol1 aptamer constitutes a highly promising and versatile platform for developing novel targeted theranostic strategies against glioblastoma, offering a precise approach for both diagnostic imaging and therapeutic intervention. Full article

Breast cancer continues to be a major challenge in global health, in part due to significant inequalities in access to costly diagnostic and therapeutic technologies based on antibodies. Their manufacturing requires complex and expensive bioproduction systems, resulting in limited availability of these tools—essential for early detection and targeted treatment—in many regions, particularly in Latin America. This gap has highlighted the need for cost-effective and scalable theranostic alternatives, increasing interest in aptamers. Obtained through SELEX technology, aptamers are synthetic DNA or RNA oligomers that fold into functional structures. Among their advantages are high affinity for their target, low immunogenicity, and chemical synthesis, which assures reproducible production. Aptamers have expanded the landscape of diagnostic platforms through the development of sensitive aptasensors, liquid biopsy strategies, and imaging systems based on nanomedicines. They also contribute to targeted therapy by recognizing cancer biomarkers selectively and enabling controlled drug delivery. This review presents a critical summary of advances in aptamer-based theranostics for breast cancer, addressing molecular mechanisms, structural folding, selective ligand binding, and nanomaterial interfacing. We also discuss applications in extracellular vesicle capture, cancer stem cell detection, and therapeutic conjugates, emphasizing their advantages and limitations relative to approaches based on antibodies. Overall, current advances show aptamers as emerging tools capable of democratizing precision oncology, particularly in regions where access to advanced technologies remains limited. Full article

Aptamers are synthetic nucleic acid ligands that have been proposed as alternatives to antibodies for targeting molecules and cells. In hematology, most reviews have organized aptamer literature around diseases or technological platforms. This framing has obscured how unevenly different blood cell types have been covered. In this review, we present developed aptamers organized by blood cell lineages. Specifically, we examine aptamers for B cells, T cells, natural killer cells, and red blood cells. This organization revealed a strong concentration on a small set of canonical surface markers and on malignant cell models. A parallel gap appeared in aptamers that distinguish differentiation stages or functional cell states. Within this framework, we evaluated reported applications, design strategies, and experimental use cases alongside persistent limitations in target selection and biological resolution. Our analysis highlighted both practical constraints and conceptual blind spots in current blood-cell-targeting aptamer research. Together, these observations defined a set of clear opportunities for expanding aptamer development toward more state-resolved, biologically informative, and clinically relevant targeting strategies. Full article

Fumonisin B1 (FB1) is a secondary metabolite produced by Fusarium species, exhibiting strong toxicity and classified as a Group 2B carcinogen by the International Agency for Research on Cancer. It poses a significant threat to both human and animal health. Therefore, developing a simple and reliable method for FB1 detection and analysis is imperative. In this study, a biosensor based on nucleic acid aptamers was developed, utilizing plasma-modified graphene oxide (mGO) as a fluorescence quencher for FB1 detection. This system leverages the interaction between mGO and FAM-APT (a nucleic acid aptamer labeled with 5-carboxyfluorescein, FAM), achieving fluorescence quenching through fluorescence resonance energy transfer (FRET) under excitation at 490 nm and emission at 520 nm. In the presence of FB1, FAM-APT specifically binds to FB1 and dissociates from the mGO surface, resulting in fluorescence recovery. Quantitative detection of FB1 was achieved by measuring the differential fluorescence intensity. The biosensor demonstrated excellent linearity over a concentration range of 10 to 5 × 10⁶ ng/L, with a detection limit (LOD) as low as 0.16 μg/L. Additionally, the sensor exhibited high specificity for FB1 among six common mycotoxins. In practical sample analysis, recovery rates ranged from 95.8% to 104.7% in corn samples and from 89.3% to 94.5% in rice samples. This aptamer-based biosensor features a simple structure, high sensitivity, and a wide detection range, providing important technical support for advancing mycotoxin research. Full article

The rapid and accurate detection of pathogenic bacteria and viruses is essential for controlling infectious disease outbreaks and ensuring food safety. Conventional detection methods such as microbial culture, immunoassays, and polymerase chain reaction (PCR), although effective, often suffer from drawbacks including time-consuming procedures, complex operations, and limited multiplexing capabilities. In recent years, electrochemical aptasensors have emerged as a promising alternative for rapid detection of pathogenic bacteria, viruses, and by-products (toxins) due to their high sensitivity, excellent specificity, low cost, and potential for miniaturization. Aptamers can be applied as biorecognition elements of the biosensor, remarkably offering advantages such as high binding affinity, thermal stability, and ease of chemical synthesis. Meanwhile, nanomaterials which provide large surface area, superior conductivity, and modifiable surfaces are widely employed in signal amplification and sensor platform construction. This review discusses the cutting-edge innovations in electrochemical aptasensors in recent years that utilize various types of nanomaterials to accurately identify and quantify diverse types of pathogens and toxins. This review focuses on nanomaterials such as metal nanostructures, carbon nanomaterials, metal, metal oxides, and carbon nanocomposites that can synergistically enhance detection sensitivity, specificity, and operational stability. This review also highlights the promising practical application of the proposed electrochemical aptasensors in clinical diagnostics, environmental monitoring, and food safety. Full article

Aptamers are powerful tools for detecting and analyzing biomolecules that consist of proteins or nucleic acids. However, their application to aptamers against viroids—highly structured self-replicating RNAs—has not yet been explored. In this study, a magnetic bead- and high-throughput sequencing-based SELEX (MB-HTS-SELEX) protocol for selecting potential aptamers against potato spindle tuber viroid (PSTVd) is presented. Full-length biotinylated-PSTVd RNA was transcribed in vitro, immobilized on streptavidin-coated magnetic beads, and incubated with a library of ~3.32 × 10¹⁴ molecules of random single-stranded oligo-DNAs (oligo-ssDNAs) of 20, 30, or 40 nucleotides (L20, L30, or L40, respectively) flanked by primer binding sites for downstream PCR amplification. Simultaneous biotin labeling of the anti-aptamer strand of the resulting double-stranded DNA (dsDNA) amplicons facilitated strand separation using streptavidin-coated magnetic beads. After 10 selection rounds, high-throughput sequencing, followed by bioinformatics analysis of the generated sequences, allowed for the detection of several enriched sequences, representing putative PSTVd-binding aptamers. Subsequent pull-down assays showed that the most abundant oligo-ssDNA in L30 was docked on PSTVd molecules. This combination method may ameliorate the selection of high-affinity aptamers against PSTVd, reduce the number of selection cycles, time, and other costs of aptamer production, thereby promoting future massive and cost-effective viroid detection and characterization. Full article

Background: CD25, the α-chain of the interleukin-2 (IL-2) receptor, is highly expressed on malignant cells and tumor-infiltrating regulatory T-cells (Tregs) in hematologic malignancies, making it an attractive therapeutic target for tumor elimination and immunomodulation. Methods: We developed a CD25-specific aptamer–drug conjugate (CD25-ApDC) by linking a CD25 aptamer to monomethyl auristatin E via a cathepsin B-cleavable Val-Cit linker. Results: The aptamer exhibited high affinity for CD25 (Kd = 16.4 ± 0.29 nM), rapid receptor-mediated uptake (half-time = 9.6 min), and selective inhibition of IL-2 signaling in CD25^high cells, with no activity in CD25^low cells. In vitro, CD25-ApDC induced selective cytotoxicity, confirmed by apoptosis and G2/M arrest in CD25-positive cancer cells while having no effect on CD25-negative cells. Co-culture studies confirmed selective depletion of CD25^high Treg-like cells, suggesting potential to relieve immune suppression within the tumor microenvironment. In vivo, CD25-ApDC achieved complete tumor remission in xenograft and disseminated models with optimized dosing, showing efficacy and tolerability comparable to Brentuximab vedotin. Increasing drug-to-aptamer ratios further enhanced outcomes, supporting flexible dosing strategies. Conclusions: These findings highlight CD25-ApDC as a promising therapeutic modality for hematologic malignancies, offering advantages in specificity, tissue penetration, and manufacturability over conventional antibody-based therapies. Full article

Electrochemical biosensors have emerged as indispensable detection tools with rapid advancements in recent years, offering high sensitivity, specificity, and cost-effectiveness for quantifying diverse analytes, including amino acids, proteins, pathogens, cells, antigens, and organic/inorganic compounds, thereby advancing analytical detection technologies across multiple fields. Aptamers, synthetic in vitro-evolved ligands with exceptional binding affinity and stability, serve as superior biorecognition elements for electrochemical sensing interfaces. Compared with other bioreceptors such as antibodies, they are generally easier and faster to produce, more uniform between batches, and easier to modify chemically; they also maintain greater stability than protein antibodies or enzymes across varying pH, temperature, and ionic conditions, enabling targeted recognition and measurable signal transduction. This review systematically summarizes recent advances in electrochemical aptasensors across three core domains: biomedical diagnostics (covering tumor markers, infectious disease pathogens, cardiovascular and metabolic biomarkers), food safety monitoring (targeting antibiotics, mycotoxins, foodborne pathogens, and pesticide residues), and environmental hazard detection (including heavy metals, toxic compounds, and biotoxins). Key technological innovations such as nanomaterial modification, signal amplification strategies, and novel sensor architectures are highlighted. Additionally, it critically discusses prominent challenges, including complex matrix interference, limited aptamer repertoires, poor reproducibility, and lack of standardization, along with future prospects. This work aims to provide a comprehensive reference for the rational design, optimization, and clinical/field application of next-generation electrochemical aptasensing technologies. Full article

This work presents the development of an automated and portable monitoring system for the point-of-need detection of tebuconazole and lambda-cyhalothrin. The system features nanoparticle/aptamer-modified electrochemical sensors that are integrated into a microfluidic chip based on polydimethylsiloxane (PDMS). More specifically, rapid and selective detection of both pesticides is achieved using target-specific aptamers immobilized on two-dimensional platinum nanoparticle films that serve as expanded nano-gapped electrodes to enhance sensor sensitivity. The effect of the device substrate (i.e., silicon versus flexible substrates) and measurement setup on biosensing performance has also been investigated. The final monitoring system is characterized by high sensitivity and selectivity in the cases of both target analytes and substrates. Τhe system features a limit of detection of 9.85 pM for tebuconazole, which is one of the lowest reported values in the literature; for lambda-cyhalothrin, it is worth noting that the results reported herein represent one of the few studies on an electrochemical aptamer-based sensor for this analyte, featuring a limit of detection of 48.5 pM. The system is also capable of selectively detecting both targets for complex cross-reactive sample matrices consisting of commercially available pesticides. Moreover, its use could be expanded to detect additional pollutants by functionalizing the biosensor surface with appropriate aptamers. Full article

Sulfamethazine (SMZ) is widely used in livestock production, and its residues can enter water and soil environments, posing potential risks to human health and ecosystems. This study focuses on environmental samples and constructs an AuNP-based colorimetric aptasensor using the SMZ1S aptamer for the rapid visual detection of SMZ. Under optimized conditions, the aptasensor showed a wide linear range from 0.05 to 0.4 µg/mL and a limit of detection of 0.039 µg/mL. Molecular dynamics simulations have demonstrated that the aptamer’s binding to SMZ is stable, providing a theoretical basis for the high selectivity of the aptasensor. Spike-and-recovery experiments yielded recoveries of 87.3–105.5%, 88.6–102.8%, and 87.5–103.4% for SMZ in lake water, tap water, and soil samples, respectively, with relative standard deviations of 5.9–8.3%, 8.0–10.6%, and 4.8–9.6%, showing good agreement with high-performance liquid chromatography (HPLC) results (R² ≥ 0.981). Overall, the proposed aptasensor provides a simple and effective approach for rapid detection of SMZ in environmental samples. Full article

In on-site rapid detection, the electrochemical method boasts high sensitivity and rapid response capabilities, while the colorimetric method can provide intuitive visual readings suitable for on-site screening. Therefore, this study developed an innovative dual-mode electrochemical/colorimetric aptasensor for the accurate detection of malathion (MAL) in vegetables. The sensor combines magnetic Fe₃O₄@ZIF-8-DNA composites and CuZr-MOF-cDNA probes, enabling simultaneous detection of the target through electrochemical reactions and colorimetric changes. The introduction of CuZr-MOF not only enhances the sensor’s conductivity but also significantly amplifies the electrochemical signal through its catalytic properties. The magnetic Fe₃O₄@ZIF-8-DNA composite facilitates solid–liquid separation under an external magnetic field. When the target MAL is present, the aptamer binds to the target, causing the CuZr-MOF-cDNA probes to release from the composite, altering the number of free probes in the supernatant and generating varying intensities of colorimetric signals. Meanwhile, the MAL captured in the precipitate by the aptamer is quantitatively detected through electrochemical methods. Experimental results demonstrate that as the target concentration increases, the colorimetric signal intensifies while the electrochemical signal weakens, showing a good linear relationship between the two. The aptasensor’s limit of detection (LOD) for colorimetric and electrochemical modes was 1.57 × 10⁻¹¹ M and 4.76 × 10⁻¹¹ M, respectively, with recoveries ranging from 87.71% to 107.68% and relative standard deviations between 3.23% and 10.75%. This method exhibits high sensitivity, excellent selectivity, and strong reliability, providing a novel technique for the accurate quantification of MAL in vegetables, particularly suited for on-site rapid detection. Full article

Pesticides are applied to promote performances in the agricultural field, sustaining crop productivity by counteracting the damages induced by pests and weeds. Under conditions of uncontrolled application, their negative influences exerted on soil, water and biodiversity mean contamination of food and impact on human health. The reactive oxygen species generation induced by pesticides impair the antioxidant protective ability. For humans, pesticides can have cytotoxic, carcinogenic, and mutagenic potential. They can be classified relying on the chemical structure or on the targeted organism. Optical sensors are based on UV-Vis absorption, fluorescence, chemiluminescence, surface plasmon resonance or Raman scattering. Based on their coloring features, nanomaterials are used in optical sensing platforms. They impart high specific surface area, small sizes, facility of surface modification by biorecognition elements (enzyme, antibody, aptamer, molecularly-imprinted polymer) and promote sensitivity and selectivity in biosensing platforms. The present paper highlights the performances of the optical sensing platforms in pesticide assay. Relevant novel applications are discussed critically, following the attempts to improve analytical features of chemical and biochemical sensors. Critical comparison of the techniques is performed in the last section. Advances in nanofabrication like the inclusion of novel nanomaterials and optimizing data interpretation by integration of algorithms can further enhance performances. Full article