Search Results (491)

Penicillin G (PEN) is a widely used antibiotic for treating microbial infections. However, its extensive use in veterinary medicine can lead to accumulation in animal-derived products, particularly milk and meat. This highlights the urgent need for rapid and sensitive antibiotic detection methods. In this study, we employed DNA aptamers for the detection of PEN and for the analysis of aptamer specificity using a combined approach based on quartz crystal microbalance with dissipation monitoring (QCM-D) and localized surface plasmon resonance (LSPR). QCM-D measures changes in resonant frequency, Δf, and dissipation, ΔD, while LSPR monitors wavelength shifts in the extinction spectra corresponding to changes at the surface of gold nanoparticles (AuNPs). Thiolated aptamers were chemisorbed onto the surface of AuNPs with a diameter of 80 nm. In the presence of PEN, a redshift in the extinction spectra and a decrease in resonant frequency were observed, accompanied by an increase in dissipation due to surface viscosity effects. Significant changes in both acoustic and LSPR signals were observed at PEN concentrations as low as 1 nM. The limits of detection (LOD) for PEN, determined by QCM-D (3.0 nM, or 1.05 ng/mL)) and LSPR (3.1 nM, or 1.09 ng/mL), were similar and both were lower than the maximum residue limit (MRL) for PEN established by the EU (4 ng/mL). Full article

As the direct energy source in organisms, accurate and simple detection of adenosine triphosphate (ATP) is of great significance. Herein, a colorimetric aptasensor for ATP determination was designed by integrating the CRISPR/Cas12a system with an aptamer, and with Prussian blue nanocube and gold nanoparticle co-functionalized MoS₂ (MoS₂-PBNCs-AuNPs) nanozymes. As expected, the introduced CRISPR/Cas12a system and aptamer could efficiently amplify the detection signal and improve the specific recognition ability, respectively. Meanwhile, the catalytic activity of the MoS₂-PBNCs-AuNPs nanozymes can be regulated with the concentration of ATP. The high-affinity binding of ATP to the aptamer competitively inhibited aptamer-crRNA hybridization, causing fewer Cas12 proteins to be activated. As a result, the uncleaved single-stranded DNA (ssDNA) adsorbed onto the surface of nanozymes to effectively enhance their catalytic oxidation capability toward 3,3′,5,5′-tetramethylbenzidine (TMB). According to this phenomenon, this CRISPR-enhanced colorimetric aptasensor can detect down to 0.14 μM ATP with high selectivity, reproducibility, and stability. In addition, acceptable recoveries and low relative standard deviations of the aptasensor for ATP determination suggest that it is promising for application in early detection of clinical-related diseases. Full article

Personalized, point-of-care testing of human tears is essential for ocular disease diagnosis, yet it is hampered by picomolar biomarker levels and microliter sample volumes. In this work, we developed an integrated, portable electrochemiluminescence (ECL)-based device for rapid and quantitative detection of tumor necrosis factor alpha (TNF-α), a pivotal inflammatory marker in ocular surface disease, with particular relevance to dry eye syndrome (DES). The device integrates a miniaturized electrochemical cell for ECL reactions and a compact silica photomultiplier for signal measurement. A vertical silica mesochannel (VSM)-coated ITO electrode is also integrated and further functionalized with TNF-α-specific aptamers. The VSM enables the enrichment of ECL luminophores, thus enabling further amplification of ECL signals and enhancing sensitivity. A wide linear range from 0.1 to 200 pg/mL was achieved using 10-fold dilution of 3 μL tear samples. Overall, this study provides a portable, highly sensitive platform for personalized analysis of TNF-α in tear fluid, enabling rapid point-of-care assessment of DES. Full article

Nucleic acid aptamers are single-stranded DNA or RNA molecules that can bind to a target with high specificity and affinity, as screened by the Systematic Evolution of Ligands by Exponential Enrichment (SELEX). In recent years, SELEX technologies have been significantly advanced for the screening of aptamers for a variety of target molecules, cells, and even bacteria and viruses. By integrating recent advances of emerging technologies with SELEX, novel screening technologies for nucleic acid aptamers have emerged with improved screening efficiency, reduced production costs and enhanced aptamer performance for a wide range of applications in medical diagnostics, drug delivery, and environmental monitoring. Aptasensors utilize aptamers to detect a wide range of analytes, allowing for the accurate identification and determination of small molecules, proteins, and even whole cells with remarkable specificity and sensitivity. Further optimization of the aptasensor can be achieved by aptamer truncation, which not only maintains the high specificity and affinity of the aptamer binding with the target analytes, but also reduces the manufacturing cost. Predictive models also demonstrate the powerful capability of determination of the minimal functional sequences by simulation of aptamer–target interaction processes, thus effectively shortening the aptamer screening procedure and reducing the production costs. This paper summarizes the research progress of protein-targeted aptamer screening in recent years, introduces several typical aptasensors at present, discusses the optimization methods of aptasensors by combining efficient SELEX with advanced predictive algorithms or post-SELEX processes, as well as the challenges and opportunities faced by aptasensors. Full article

Recent advances in computational tools, particularly machine learning (ML), deep learning (DL), and structure-based modeling, are transforming aptamer research by accelerating discovery and enhancing biosensor development. This review synthesizes progress in predictive algorithms that model aptamer–target interactions, guide in silico sequence optimization, and streamline design workflows for both laboratory and point-of-care diagnostic platforms. We examine how these approaches improve key aspects of aptasensor development, such as aptamer selection, sensing surface immobilization, signal transduction, and molecular architecture, which contribute to greater sensitivity, specificity, and real-time diagnostic capabilities. Particular attention is given to illuminating the technological and experimental advances in structure-switching aptamers, dual-aptamer systems, and applications in electrochemical, optical, and lateral flow platforms. We also discuss current challenges such as the standardization of datasets and interpretability of ML models and highlight future directions that will support the translation of aptamer-based biosensors into scalable, point-of-care and clinically deployable diagnostic solutions. Full article

The alarming rise in foodborne illnesses, particularly those associated with microbial contamination in meat products, presents a serious challenge to global food safety. Among these microbial threats, Pseudomonas aeruginosa (P. aeruginosa) poses a critical threat due to its biofilm-forming capability and prevalence in contaminated beef, highlighting its effective real-time detection. Herein, we report the fabrication of a novel electrochemical aptasensor based on multimetal perovskite (FeCoCuNiO) doped with urea-derived graphitic carbon nitride (g-C₃N₄), synthesized via a sol–gel combustion method. The FeCoCuNiO-g-C₃N₄ nanocomposite was then coated onto a graphitic pencil electrode and functionalized with a DNA-based aptamer specific towards P. aeruginosa. The resulting aptasensor exhibited a low detection limit of 3.03 CFU mL⁻¹ with high selectivity and sensitivity, and was successfully applied to real-time detection of P. aeruginosa in food samples. To the best of our knowledge, this work presents the first FeCoCuNiO-g-C₃N₄-based aptasensor for bacterial detection, offering a promising platform for food safety assurance and public health protection. Full article

The presence of hazardous substances in food poses a serious threat to our health. It is important to develop fast, convenient, and inexpensive assays for on-site sensitive analysis of various hazards in food. With the emergence and popularization of aptamers and biosensors, aptasensors have gradually become one of the most important detection techniques for substances such as nucleic acids and small molecules. This paper reviews the recent research progress in the field of aptasensor based on different technologies (such as electrochemistry, fluorescence, colorimetry, among others) for the rapid detection of hazards (such as foodborne pathogens, mycotoxins, pesticides, among others) in food. In addition, the current challenges of different aptasensors are described for the readers, and the future direction of aptasensors is envisioned by comparing the different technologies in order to develop a more suitable aptasensor. This review will not only promote the advancement of aptasensors but also their practical application in daily life to safeguard human health and food safety. Full article

Despite the substantial human health risks posed by ochratoxin A (OTA), a potent mycotoxin, simple, low-cost methods for its sensitive and selective detection in foods are lacking. To address this gap, we herein developed a label-free OTA aptasensor based on deoxyribonucleic acid (DNA)-scaffolded silver nanoclusters (AgNCs) with an intense red fluorescence. As the DNA template fragment used for AgNC fabrication was derived from the complementary sequence of the OTA aptamer (Apt-OTA), Apt-OTA complexed the AgNCs in the absence of OTA, quenching their fluorescence. OTA inhibited this quenching by strongly binding Apt-OTA and thus precluding its binding to the AgNCs. The OTA aptasensor exhibited a high selectivity and low detection limit (0.38 ng/mL), eliminating the need for expensive reagents, complicated pre-treatments, and advanced equipment, and was successfully used to quantify mycotoxins in food under real-life conditions, thus holding promise for mycotoxin control. Full article

The combination of rGO-FETs (reduced Graphene Oxide Field-Effect Transistors) and DNA-oligonucleotide aptamers to sense analytes has been shown to be a promising technological approach, achieving high sensitivity and selectivity. With human adenovirus type 5 (HAdV-5) particles as the target, we here demonstrate the application of the aptamer/FET combination for detection of this medically and biotechnologically relevant viral vector. A focused anti-HAdV-5 aptamer library was evolved in a nine-round SELEX process, allowing for the specific fluorescent labeling of HAdV-5 and related subtypes. Moreover, this library was already sufficient to serve as the binding entity on a gFET sensor for sensitive quantification of the virus particles. Adenoviruses have been widely used as gene delivery vectors for gene therapy and genetic vaccination. The use of adenoviral vectors within the vaccination campaign against COVID-19 emphasized the need for robust biotechnological production processes, which additionally require sensitive product formation monitoring. We believe that these type of gFET-based aptasensors can serve as the technological monitoring basis in virus production processes in the near future. Full article

Aptasensors are biosensors that rely on an aptamer’s ability to selectively bind targets. To produce a signal indicative of successful binding, aptamers are frequently modified with reporter agents. However, modification of aptamers with specific reporter agents affects subsequent aptamer-target binding, resulting in time-consuming screening assays to identify suitable aptamers capable of binding, once modified. To address this, this study proposes a SELEX approach that amplifies an enriched aptamer pool using a 5′-biotin-C6-phosphoramidite modification and using that for subsequent selection of suitable sequences capable of binding when modified. For this study, fractions from an existing enriched aptamer pool from a previous SELEX for hCG aptamers were separately amplified utilising biotinylated and non-biotinylated (unmodified) primers and sequenced via nanopore next-generation sequencing. While several enriched sequences were represented within the pools, bioinformatic analysis of the pools indicated subtle clustering of sequences between pools. However, the disparity in the number of sequences between both pools may indicate a possible amplification or sequencing-based bias caused by the biotinylation. This approach has merit to support aptamer SELEX strategies but may require further validation. Full article

Biodetection, the basis of many biotechnologies, has rapidly developed in recent years. Among various biodetection methods, the photoelectrochemical (PEC) sensor is an emerging analytical method and has been applied in biodetection widely because of its high sensitivity, low cost, expandability into multichannel sensor arrays, and many other superior properties. Unlike conventional electrochemical aptasensors, the PEC aptasensor uses light as the excitation and an electrical photocurrent as the readout, which separates the stimulus from the measurement and reduces the excitation-related background. By modulating the light and demodulating the current, the PEC aptasensor improves the signal-to-noise ratio and lowers the limit of detection in complex matrices. Compared with optical aptasensors, the PEC aptasensor relies on simple light sources and electrodes rather than bulky imaging optics, enabling easier miniaturization and light-addressed multiplexed arrays. Therefore, aptamer-based PEC aptasensors have become a new hotspot in the field of biodetection. In this review, the development history of PEC aptasensors was presented. Then, this paper focuses on the photoactive nanomaterials, aptamers as sensing films, and sensing strategies of PEC aptasensors. The applications of PEC aptasensors in biodetection were also discussed. Finally, current challenges are discussed and opportunities in the future are prospected. Full article

The prevalence of food allergies has been steadily increasing in recent years. β-lactoglobulin (β-LG), the main allergenic protein of milk and dairy allergies, is more commonly observed in infants and children. In this study, a β-LG-specific aptamer was selected using the combinatorial chemistry process known as systematic evolution of ligands by exponential enrichment (SELEX), and a quartz crystal microbalance with dissipation monitoring (QCM-D)-based aptasensor was developed using a novel surface functionalization technique, which mimics an artificial cell membrane on the QCM-D sensor surface, creating a physiologically relevant environment for the binding of the target to the sensor. Through SELEX combined with next-generation sequencing (NGS), the aptamer Apt 356 was identified. Its binding to β-LG was confirmed via dot blot analysis. The selected Apt 356 was then used for the development of a QCM-D-based sensor. To fabricate the sensor, the quartz surface was functionalized with a supported lipid bilayer (SLB). The β-LG-specific aptamer was immobilized onto this SLB. The results demonstrated that the QCM-D system allows real-time observation and evaluation of the binding of β-LG. While there have been some studies on aptasensors for the β-LG protein, to the best of our knowledge, this is the first QCM-D-based aptasensor developed specifically for β-LG protein detection. Full article

This review aims to point out the main achievements in the cutting-edge field of aptamer nanotechnology and its applications in the most frequent neuro-oncological and neurodegenerative diseases. The article discusses the properties, advantages and drawbacks of aptamers (AP), and their design and selection by various SELEX methods, as well as the synergical advantages as theranostics of the aptamer-functionalized nanoparticles (Ap-NP). The Ap-nanoconjugates properties are compared to those of Ap and unconjugated NP. Moreover, the article comparatively analyzes the aptamer-based approaches vs. antibody-drug conjugates vs. exosome-based delivery systems vs. unconjugated NP, as targeted therapies in neurodegenerative diseases and gliomas. The review presents major challenges in Ap-NP conjugates’ clinical progress (concerning the in vivo enzymatic stability, blood–brain barrier (BBB) permeability, selective intracellular uptake in the brain parenchyma and target tissues, rapid renal clearance, off-target toxicity, immunogenicity, reproductible manufacturing) and the investigated developmental strategies to solve them. Furthermore, relevant examples and comparative insights regarding preclinically tested Ap and Ap-NP conjugates are presented for targeted delivery systems loaded with chemotherapeutical drugs or genes, Ap-siRNA chimeras and immunotherapeutical aptamers, which are evaluated in glioblastomas (GBM), amyloidogenic diseases and multiple sclerosis (MS); radiotherapy enhancers in GBM; aptasensors for diagnostic and bioimaging-guided therapy in GBM, MS and amyloidopathies. The review finally points out future research directions in order to accelerate the clinical translation and the real-world impact as theranostics of the most preclinically advanced Ap-NP conjugates in major neuro-oncological and neurodegenerative disorders. Full article

Inflammatory bowel disease (IBD) is a relapsing–remitting condition resulting in chronic inflammation of the gastrointestinal tract. Present methods are either inadequate or not viable for continuous tracking of disease progression in individuals. In this study, we present the development towards an implantable biosensor for detecting interleukin-6 (IL-6), an important cytokine implicated in IBD. The optimised sensor design includes a gold surface functionalised with a known IL-6-specific aptamer, integrating a recognition sequence and an electrochemical redox probe. The IL-6 aptasensor demonstrated a sensitivity of up to 40% and selectivity up to 10% to the IL-6 target in vitro. Sensors were found to degrade over 7 days when exposed to recombinant IL-6, with the degradation rate rapidly increasing when exposed to intestinal mucosa. A feasibility in vivo experiment with a newly designed implantable gut sensor array confirmed rapid degradation over a 5-h implantation period. We achieved up to a 93% reduction in sensor degradation rates, with a polyvinyl alcohol–methyl acrylate hydrogel coating that aimed to reduce nonspecific interactions in complex analytes compared to uncoated sensors. Degradation was linked to desorption of the monolayer leading to breakage of gold thiol bonds. While there are key challenges to be resolved before a stable implantable IBD sensor is realised, this work highlights the potential of aptamer-based biosensors as effective tools for long-term diagnostic monitoring in IBD. Full article