Aptamer Targeting Research Articles

Real-time Visualization of "Small Molecules-ssDNA" Complexes for Aptamer Screening based on Online Competition CE-SELEX

Capillary electrophoresis-based systematic evolution of ligands by exponential enrichment (CE-SELEX) is one of the most efficient techniques for aptamers screening. However, CE-SELEX is generally considered challenging for small molecule targets due to a slight charge-to-mass ratio (z/m) difference that fails to create a clear separation between small molecule-ssDNA complexes and ssDNA libraries, thus heavily restricting the screening target scopes. Herein, a novel online competition CE-SELEX (ocCE-SELEX) strategy was introduced for real-time visualization of "small molecules-ssDNA" complexes to screen aptamers for small molecule targets in free solution. To achieve this vision, the "pair-wise" interaction-based "Catcher-ssDNA-Target" ternary system was flexibly designed via online CE mode. First, we introduced a conceptual protein of an ssDNA catcher (Catcher) that is capable of capturing all sequences in ssDNA library completely through an online controllable procedure by adjusting the injection time of different zones, resulting in the disappearance of original peaks of the ssDNA library in electropherogram. Then, the "pair-wise" interaction would restore the peaks through an online competition process, in which the Catcher with a faster migration rate would traverse the equilibrium zone of small molecule/ssDNA mixture and capture free ssDNA, as well as compete with small molecules to capture weakly bound ssDNA sequences. Due to the different z/m changes, the ssDNA captured by Catcher continues to migrate rapidly and the retained ssDNA in small molecule-ssDNA complex approximately maintains its original migration rate. Consequently, the peaks of Catcher-captured ssDNA and small molecule-ssDNA complex achieved complete separation and real-time visualization, allowing the complex to be collected readily. Furthermore, the implementation of ocCE-SELEX strategy was verified with two small molecules (vitamin B12 and ofloxacin) and six polypeptides. The study expands the application of CE-SELEX in small molecules in terms of real-time visualization and accurate collection of small molecules-ssDNA complexes, opening a new path for aptamer screening for small molecule targets in their natural state.

Polyvalent Aptamer Nanodrug Conjugates Enable Efficient Tumor Cuproptosis Therapy Through Copper Overload and Glutathione Depletion.

Cuproptosis, a recently identified form of copper-dependent cell death, shows promising tumor suppressive effects with minimal drug resistance. However, its therapeutic efficacy is hampered by its dependence on copper ions and the glutathione (GSH)-rich microenvironment in tumors. Here, we have developed polyvalent aptamer nanodrug conjugates (termed CuPEs@PApt) with a nucleosome-like structure to improve tumor cuproptosis therapy by exploiting mitochondrial copper overload and GSH depletion. Polyvalent aptamer (PApt), comprising polyvalent epithelial cell adhesion molecule aptamers for tumor targeting and repetitive PolyT sequences for copper chelation, facilitates efficient loading and targeted delivery of copper peroxide-Elesclomol nanodots (CuPEs). Upon internalization by tumor cells, Elesclomol released from CuPEs@PApt accumulates copper ions in mitochondria to initiate cuproptosis, while lysosomal degradation of CuP nanodots generates exogenous Cu2+ and H2O2, triggering a Fenton-like reaction for GSH depletion to enhance cuproptosis. In vitro and in vivo experiments confirm the efficacy of this strategy in inducing tumor cell cuproptosis and immunogenic cell death, the latter contributing to the activation of the antitumor immune response for synergistic tumor growth inhibition.

Adaptation of a Model Spike Aptamer for Isothermal Amplification-Based Sensing.

Isothermal amplification (IA) techniques like rolling circle amplification (RCA) and loop-mediated isothermal amplification (LAMP) have gained significant attention in recent years due to their ability to rapidly amplify DNA or RNA targets at a constant temperature without the need for complex thermal cycling equipment. Such technologies, combined with colorimetric systems rendering visual confirmation of the amplification event, are ideal for the development of point-of-need detection methods suitable for field settings where access to specialized laboratory equipment is limited. The utility of these technologies, thus far limited to DNA and RNA targets, could be broadened to a wide range of targets by using aptamers. Composed of DNA or RNA themselves, aptamers can bind to substances, including proteins, metabolites, and inorganic substances. Their nucleic acid nature can potentially allow them to serve as a bridge, extending the reach of DNA/RNA-centric technologies to the broader molecular world. Indeed, the change in aptamer conformation occurring during ligand interaction can be used to elaborate ligand-responding RCA or LAMP templates. By using an existing aptamer targeting SARS-CoV-2 Spike protein as a model, we explored the possibility of establishing ligand-responsive IA systems. Our study used aptamers with simple sequence modifications as templates in LAMP assays and hyperbranched RCA (HRCA) by exploiting the dynamic nature of the model aptamer to trigger these IA systems. Importantly, our work uniquely demonstrates that this aptamer's dynamic response to ligand binding can regulate both RCA and LAMP processes. This novel approach of using aptamer conformational changes to trigger LAMP paves the way for new aptamer-based detection assays. Our system detects 50 nM of Spike protein, with LAMP occurring within 30 min in the presence of Spike. The colorimetric readout showed clear results, allowing for the detection of Spike protein presence.

Proteomic Signatures of Right Ventricular Outcomes in Pulmonary Arterial Hypertension.

Pulmonary arterial hypertension (PAH) is a disease of progressive right ventricular (RV) failure with high morbidity and mortality. Our goal is to investigate proteomic features and pathways associated with RV-focused outcomes including mortality, RV dilation, and NT-proBNP (N-terminal pro-B-type natriuretic peptide) in PAH. Participants in a single-institution cohort with 3 years of follow-up underwent proteomic profiling of their plasma using 7288 aptamers (targeting 6467 unique human proteins). Partial least squares discriminant analysis was performed to assess global protein variation associated with mortality, RV dilation, and NT-proBNP levels. Differentially abundant proteins and enriched pathways associated with outcomes were identified following baseline adjustments. RV vulnerability models estimated associations for individuals with similar afterload following adjustment for pulmonary vascular resistance. A total of 117 participants with PAH were included. Partial least squares discriminant analysis of the proteome showed clear separation between survivors and nonsurvivors, participants with dilated versus nondilated RVs, and across NT-proBNP levels. Proteins and pathways involving the ECM (extracellular matrix) were upregulated in participants who died during follow-up, those with severe RV dilation, and those with higher levels of NT-proBNP. Pulmonary vascular resistance adjustment reinforced the importance of ECM proteins in the association with RV vulnerability, independent of afterload. These findings were confirmed in independent PAH cohorts with available plasma proteomics and RV tissue gene and protein expression. Distinct plasma proteomic profiles are associated with mortality, RV dilation, and NT-proBNP in PAH. Proteins and pathways governing tissue remodeling are strongly associated with poor outcomes, may mediate RV vulnerability to right heart failure, and represent promising candidates as biomarkers and potential therapeutic targets.

A disposable paper-based electrochemical biosensor for detection of aflatoxin B1 based on a structure-switching aptamer

Aflatoxin B1 (AFB1) is a highly toxic mycotoxin that readily contaminates major food crops. This study presents a novel ratiometric electrochemical paper-based aptasensor for AFB1 detection that utilizes a structure-switching aptamer. The sensor detects AFB1 by folding the DNA aptamer, reducing the electron transfer efficiency between the methylene blue (MB) molecules attached to the DNA and the electrode surface. An inner reference element modified with ferrocene (Fc) is co-assembled on the electrode surface of the paper-based biosensor to enhance the accuracy of AFB1 detection. In the presence of target AFB1, a folded target–aptamer complex is formed, distancing the MB molecules from the electrode and generating a low current signal in a differential pulse voltammetry mode. The ratio of oxidation currents for MB and Fc serves as the metric for monitoring AFB1 levels. The detection range spans from 20.0 to 1000.0 ng mL−1, with a limit of detection of 7.6 ng mL−1. The paper-based aptasensor exhibits excellent specificity and stability. Additionally, its high reliability and applicability are validated by the strong correlation observed between the sensor results and the results obtained using UPLC−MS/MS analysis of real samples. This study offers a low-cost, readily available approach for portable detection of foodborne hazards.

Development of Targeted Drug Delivery System for the Treatment of SARS-CoV-2 Using Aptamer-Conjugated Gold Nanoparticles

Background: The SARS-CoV-2 pandemic has highlighted niclosamide (NIC) as a promising treatment for COVID-19. However, its clinical application is limited due to its poor water solubility, resulting in low bioavailability. Methods: To address this issue, we developed a AuNP-HA-NIC system, which combines gold nanoparticles with hyaluronic acid to enhance drug delivery. Our comprehensive characterization of the system revealed that hyaluronic acid with specific molecular weights, particularly those exposed to electron-beam irradiation between 2 and 20 kGy, produced the most stable nanoparticles for efficient drug loading and delivery. Results: Additionally, the AuNP-HA-NIC system exhibits a significant sensitivity to pH changes, which is a critical feature for targeted drug release. Under acidic conditions mimicking the stomach and small intestine, minimal drug release was observed, indicating the effective prevention of premature drug release in the gastrointestinal tract. Furthermore, the integration of a targeting aptamer established specific binding abilities towards the SARS-CoV-2 spike protein, distinguishing it from other coronaviruses. Conclusions: As research progresses, and with further in vivo testing and optimization, the AuNP-HA-NIC–aptamer system holds great promise as a game-changer in the field of antiviral therapeutics, particularly in the battle against COVID-19.

Functional Aptamers In Vitro Evolution for Intranuclear Blockage of RNA-Protein Interaction.

Over the last 30 years, despite considerable research and endeavors aimed at harnessing aptamers as pharmaceutical molecules, the progress in developing aptamer-based drugs has been falling short of expectations. Sequential steps of affinity molecule acquisition and functional screening are typically required for discovering affinity-based macromolecule therapeutics, which can be time-consuming and limiting in candidate selection. Additionally, aptamers often necessitate tedious postselection modifications to overcome pharmacokinetic limitations, which usually impede the binding affinity. Herein, we propose a novel in vitro screening platform termed Functional Aptamers in vitro Evolution (FAIVE), which integrates affinity molecule acquisition with functional screening and introduces chemical diversity during the process. This platform aims to rapidly generate functional aptamers capable of binding to target proteins and regulating their functions. Illustrated by targeting intranuclear RNA-protein interactions involving HIV-1 Tat protein and TAR RNA, FAIVE demonstrates a selection of functional aptamers with significant intracellular blocking effects. The study also explores lipid nanoparticle delivery systems to enhance intracellular delivery efficiency, expanding aptamer targeting potential to broader intracellular and intranuclear domains. This study emphasizes the potential of FAIVE to expedite the development of aptamer-based drugs and facilitate the creation of more versatile and effective therapeutics.

Unlocking precision in aptamer engineering: a case study of the thrombin binding aptamer illustrates why modification size, quantity, and position matter.

The thrombin binding aptamer (TBA) is a prototypical platform used to understand the impact of chemically-modified nucleotides on aptamer stability and target affinity. To provide structural insight into the experimentally-observed effects of modification size, location, and number on aptamer performance, long time-scale molecular dynamics (MD) simulations were performed on multiple binding orientations of TBA-thrombin complexes that contain a large, flexible tryptophan thymine derivative (T-W) or a truncated analogue (T-K). Depending on modification position, T-W alters aptamer-target binding orientations, fine-tunes aptamer-target interactions, strengthens networks of nucleic acid-protein contacts, and/or induces target conformational changes to enhance binding. The proximity and 5'-to-3' directionality of nucleic acid structural motifs also play integral roles in the behavior of the modifications. Modification size can differentially influence target binding by promoting more than one aptamer-target binding pose. Multiple modifications can synergistically strengthen aptamer-target binding by generating novel nucleic acid-protein structural motifs that are unobtainable for single modifications. By studying a diverse set of modified aptamers, our work uncovers design principles that must be considered in the future development of aptamers containing chemically-modified nucleotides for applications in medicine and biotechnology, highlighting the value of computational studies in nucleic acids research.

EpCAM-targeted betulinic acid analogue nanotherapy improves therapeutic efficacy and induces anti-tumorigenic immune response in colorectal cancer tumor microenvironment

BackgroundBetulinic acid (BA) has been well investigated for its antiproliferative and mitochondrial pathway-mediated apoptosis-inducing effects on various cancers. However, its poor solubility and off-target activity have limited its utility in clinical trials. Additionally, the immune modulatory role of betulinic acid analogue in the tumor microenvironment (TME) is largely unknown. Here, we designed a potential nanotherapy for colorectal cancer (CRC) with a lead betulinic acid analogue, named as 2c, carrying a 1,2,3-triazole-moiety attached to BA through a linker, found more effective than BA for inhibiting CRC cell lines, and was chosen here for this investigation. Epithelial cell adhesion molecule (EpCAM) is highly overexpressed on the CRC cell membrane. A single-stranded short oligonucleotide sequence, aptamer (Apt), that folds into a 3D-defined architecture can be used as a targeting ligand for its specific binding to a target protein. EpCAM targeting aptamer was designed for site-specific homing of aptamer-conjugated-2c-loaded nanoparticles (Apt-2cNP) at the CRC tumor site to enhance therapeutic potential and reduce off-target toxicity in normal cells. We investigated the in vitro and in vivo therapeutic efficacy and anti-tumorigenic immune response of aptamer conjugated nanotherapy in CRC-TME.MethodsAfter the characterization of nanoengineered aptamer conjugated betulinic acid nanotherapy, we evaluated therapeutic efficacy, tumor targeting efficiency, and anti-tumorigenic immune response using cell-based assays and mouse and rat models.ResultsWe found that Apt-2cNP improved drug bioavailability, enhanced its biological half-life, improved antiproliferative activity, and minimized off-target cytotoxicity. Importantly, in an in vivo TME, Apt-2cNP showed promising signs of anti-tumorigenic immune response (increased mDC/pDC ratio, enhanced M1 macrophage population, and CD8 T-cells). Furthermore, in vivo upregulation of pro-apoptotic while downregulation of anti-apoptotic genes and significant healing efficacy on cancer tissue histopathology suggest that Apt-2cNP had predominantly greater therapeutic potential than the non-aptamer-conjugated nanoparticles and free drug. Moreover, we observed greater tumor accumulation of the radiolabeled Apt-2cNP by live imaging in the CRC rat model.ConclusionsEnhanced therapeutic efficacy and robust anti-tumorigenic immune response of Apt-2cNP in the CRC-TME are promising indicators of its potential as a prospective therapeutic agent for managing CRC. However, further studies are warranted.Graphical abstract

A novel mesenchymal stem cell-targeting dual-miRNA delivery system based on aptamer-functionalized tetrahedral framework nucleic acids: Application to endogenous regeneration of articular cartilage

Articular cartilage injury (ACI) remains one of the key challenges in regenerative medicine, as current treatment strategies do not result in ideal regeneration of hyaline-like cartilage. Enhancing endogenous repair via microRNAs (miRNAs) shows promise as a regenerative therapy. miRNA-140 and miRNA-455 are two key and promising candidates for regulating the chondrogenic differentiation of mesenchymal stem cells (MSCs). In this study, we innovatively synthesized a multifunctional tetrahedral framework in which a nucleic acid (tFNA)-based targeting miRNA codelivery system, named A-T-M, was used. With tFNAs as vehicles, miR-140 and miR-455 were connected to and modified on tFNAs, while Apt19S (a DNA aptamer targeting MSCs) was directly integrated into the nanocomplex. The relevant results showed that A-T-M efficiently delivered miR-140 and miR-455 into MSCs and subsequently regulated MSC chondrogenic differentiation through corresponding mechanisms. Interestingly, a synergistic effect between miR-140 and miR-455 was revealed. Furthermore, A-T-M successfully enhanced the endogenous repair capacity of articular cartilage in vivo and effectively inhibited hypertrophic chondrocyte formation. A-T-M provides a new perspective and strategy for the regeneration of articular cartilage, showing strong clinical application value in the future treatment of ACI.

Triangle-toothed gear occlude-guided universal nanotechnology constructs 3D symmetric DNA polyhedra with high assembly efficiency for precision cancer therapy

Chemotherapy is commonly used to treat malignant tumors. However, conventional chemotherapeutic drugs often cannot distinguish between tumor and healthy cells, resulting in adverse effects and reduced therapeutic efficacy. Therefore, zigzag-shaped gear-occlude-guided cymbal-closing (ZGC) DNA nanotechnology was developed based on the mirror-symmetry principle to efficiently construct symmetric DNA polyhedra. This nanotechnology employed simple mixing steps for efficient sequence design and assembly. A targeting aptamer was installed at a user-defined position using an octahedron as a model structure. Chemotherapeutic drug-loaded polyhedral objects were subsequently delivered into tumor cells. Furthermore, anticancer drug-loaded DNA octahedra were intravenously injected into a HeLa tumor-bearing mouse model. Assembly efficiency was almost 100 %, with no residual building blocks identified. Moreover, this nanotechnology required a few DNA oligonucleotides, even for complex polyhedrons. Symmetric DNA polyhedrons retained their structural integrity for 24 h in complex biological environments, guaranteeing prolonged circulation without drug leakage in the bloodstream and promoting efficient accumulation in tumor tissues. In addition, DNA octahedra were cleared relatively slowly from tumor tissues. Similarly, tumor growth was significantly inhibited in vivo, and a therapeutic outcome comparable to that of conventional gene-chemo combination therapy was observed. Moreover, no systemic toxicity was detected. These findings indicate the potential application of ZGC DNA nanotechnology in precision medicine.

Aptamer-functionalized triptolide with release controllability as a promising targeted therapy against triple-negative breast cancer

Targeted delivery and precise release of toxins is a prospective strategy for the treatment of triple-negative breast cancer (TNBC), yet the flexibility to incorporate both properties simultaneously remains tremendously challenging in the X-drug conjugate fields. As critical components in conjugates, linkers could flourish in achieving optimal functionalities. Here, we pioneered a pH-hypersensitive tumor-targeting aptamer AS1411-triptolide conjugate (AS-TP) to achieve smart release of the toxin and targeted therapy against TNBC. The multifunctional acetal ester linker in the AS-TP site-specifically blocked triptolide toxicity, quantitatively sustained aptamer targeting, and ensured the circulating stability. Furthermore, the aptamer modification endowed triptolide with favorable water solubility and bioavailability and facilitated endocytosis of conjugated triptolide by TNBC cells in a nucleolin-dependent manner. The integrated superiorities of AS-TP promoted the preferential intra-tumor triptolide accumulation in xenografted TNBC mice and triggered the in-situ triptolide release in the weakly acidic tumor microenvironment, manifesting striking anti-TNBC efficacy and virtually eliminated toxic effects beyond clinical drugs. This study illustrated the therapeutic potential of AS-TP against TNBC and proposed a promising concept for the development of nucleic acid-based targeted anticancer drugs.

Rapid Nuclease-Assisted Selection of High-Affinity Small-Molecule Aptamers.

Aptamers are nucleic acid bioreceptors that have been widely utilized for a variety of biosensing applications, including in vivo detection methods that would not be possible with antibody-based systems. However, it remains challenging to generate high-quality aptamers for small molecule targets, particularly for use under physiological conditions. We present a highly effective aptamer selection technology for small-molecule targets that utilizes the nuclease EcoRI to remove nonspecific or weakly binding sequences in solution phase, rapidly enriching high-affinity target binders within just a few rounds of selection. As proof-of-concept, we used our nuclease-assisted SELEX (NA-SELEX) method to isolate aptamers for a synthetic cannabinoid, AB-FUBINACA. Within five rounds, we identified two highly specific aptamers that exhibit nanomolar affinity at physiological temperature. We also demonstrate the robustness and reproducibility of NA-SELEX by performing the same selection experiment with fresh reagents and libraries, obtaining the same two aptamers as well as two other high-quality aptamer candidates. Finally, we compare NA-SELEX against a conventional library-immobilized SELEX screen for AB-FUBINACA using the same screening conditions, identifying aptamers with 25-100-fold weaker affinity after 11 rounds of selection. NA-SELEX therefore could be an effective selection method for the isolation of high-quality aptamers for small-molecule targets.

Selection and characterisation of DNA aptamer targeting immunogenic peptide sequence of high molecular weight glutenin (HMW-GS) of gluten

Selection and characterisation of DNA aptamer targeting immunogenic peptide sequence of high molecular weight glutenin (HMW-GS) of gluten

Structure-based investigation of a DNA aptamer targeting PTK7 reveals an intricate 3D fold guiding functional optimization

DNA aptamers have emerged as novel molecular tools in disease theranostics owing to their high binding affinity and specificity for protein targets, which rely on their ability to fold into distinctive three-dimensional (3D) structures. However, delicate atomic interactions that shape the 3D structures are often ignored when designing and modeling aptamers, leading to inefficient functional optimization. Challenges persist in determining high-resolution aptamer-protein complex structures. Moreover, the experimentally determined 3D structures of DNA molecules with exquisite functions remain scarce. These factors impede our comprehension and optimization of some important DNA aptamers. Here, we performed a streamlined solution NMR-based structural investigation on the 41-nt sgc8c, a prominent DNA aptamer used to target membrane protein tyrosine kinase 7, for cancer theranostics. We show that sgc8c prefolds into an intricate three-way junction (3WJ) structure stabilized by long-range tertiary interactions and extensive base-base stackings. Delineated by NMR chemical shift perturbations, site-directed mutagenesis, and 3D structural information, we identified essential nucleotides constituting the key functional elements of sgc8c that are centralized at the core of 3WJ. Leveraging the well-established structure-function relationship, we efficiently engineered two sgc8c variants by modifying the apical loop and introducing L-DNA base pairs to simultaneously enhance thermostability, biostability, and binding affinity for both protein and cell targets, a feat not previously attained despite extensive efforts. This work showcases a simplified NMR-based approach to comprehend and optimize sgc8c without acquiring the complex structure, and offers principles for the sophisticated structure-function organization of DNA molecules.

A Comprehensive Review Of Potentiometric Biosensors

Potentiometry based on ion-selective electrodes (ISEs) has undergone a renaissance with improvements in the detection limits and selectivities of ISEs, the introduction of new materials, new sensing concepts (from conventional potentiometry to dynamic electrochemistry approaches), and deeper theoretical understanding and modelling of the potentiometric responses of ISEs. The most recent innovations support improvements in software for ion sensing and biosensing. Additionally, adaptable sensing techniques have been created for a wide range of various target molecules, including enzymes, antibodies, aptamers, and peptides, in response to the introduction of new receptors by using ISEs as powerful transducers. Current potentiometric biosensor trends are examined in this paper. Their applications in the biosensing of metal ions, small molecules, DNA, proteins, microorganisms, and poisons have been discussed. This review provides a forecast for potentiometric biosensing based on the integration of potentiometric ISEs with innovative materials and cutting-edge techniques.

DNA programmed Mg-Al layered double hydroxide-based bi-adjuvant nanovaccines

Implementation of adjuvants is a requirement for inducing antigen-specific immune responses against infectious diseases. The conventional aluminum adjuvants used in clinical trials suffer from insufficient cellular immune response. Herein, we develop a bi-adjuvant nanovaccine containing receptor-binding domain (RBD) as antigen and DNA programmed Mg/Al layered double hydroxide (Mg/Al-LDH) as adjuvants, and thus achieve co-activation of potent humoral and cellular immune responses. The Mg/Al-LDH consisting of positively charged layers is firstly employed as scaffold to adsorb antigen via electrostatic interaction, and then CpG and dendritic cell (DC)-targeting aptamers co-encoded ultra-long DNA chains are easily decorated on the Mg/Al-LDH via interfacial assembly. The nanoscale formulations and interfacial targeting aptamers of nanovaccine facilitate their endocytosis by DC cells; the Mg/Al-LDH structure is acid-responsive and ensures the Al ions-inducing antigen cross-presentation for durable generation of antibody (Th2 immune response); and the agonist CpG in DNA chains can bind to the Toll-like receptor 9 (TLR 9) to activate cellular immunity (Th1 immune response). The bi-adjuvant nanovaccine fully combines the advantages of nanosheet alum-like adjuvant and precisely customization of DNA, and thus balances the Th1/Th2 immune response for compensating the deficiency of traditional alum adjuvant, providing a design guidance for creating next-generation of safe and efficient adjuvants in immunology.

Nuclease-assisted selection of slow-off rate aptamers.

Conventional directed evolution methods offer the ability to select bioreceptors with high binding affinity for a specific target in terms of thermodynamic properties. However, there is a lack of analogous approaches for kinetic selection, which could yield affinity reagents that exhibit slow off-rates and thus remain tightly bound to targets for extended periods. Here, we describe an in vitro directed evolution methodology that uses the nuclease flap endonuclease 1 to achieve the efficient discovery of aptamers that have slow dissociation rates. Our nuclease-assisted selection strategy can yield specific aptamers for both small molecules and proteins with off-rates that are an order of magnitude slower relative to those obtained with conventional selection methods while still retaining excellent overall target affinity in terms of thermodynamics. This new methodology provides a generalizable approach for generating slow off-rate aptamers for diverse targets, which could, in turn, prove valuable for applications including molecular devices, bioimaging, and therapy.

Selection of structure-induced aptamer targeting small molecule based on capillary sieving electrophoresis.

In this study, a structure-induced aptamer targeting small molecules was selected using capillary sieving electrophoresis (CSE). CSE was conducted using a capillary filled with a background solution containing hydroxypropyl cellulose as a sieving matrix to separate the aptamer candidates by changing their structures via complexation. Before aptamer selection, the original random-sequence DNA library was used to create structure-not-preorganized DNA sub-library containing straight-chain-like structures using CSE. Next, a structure-induced aptamer targeting L-tyrosinamide was selected from the prepared sub-library. Six aptamer candidates were selected, one of which showed a binding ability comparable to that of the reported L-tyrosinamide aptamer and selectivity toward the analogs. These results indicated that the proposed method can be applied to select structure-induced aptamers that target small molecules.

Advances in Aptamer-Based Conjugate Recognition Techniques for the Detection of Small Molecules in Food.

Small molecules are significant risk factors for causing food safety issues, posing serious threats to human health. Sensitive screening for hazards is beneficial for enhancing public security. However, traditional detection methods are unable to meet the requirements for the field screening of small molecules. Therefore, it is necessary to develop applicable methods with high levels of sensitivity and specificity to identify the small molecules. Aptamers are short-chain nucleic acids that can specifically bind to small molecules. By utilizing aptamers to enhance the performance of recognition technology, it is possible to achieve high selectivity and sensitivity levels when detecting small molecules. There have been several varieties of aptamer target recognition techniques developed to improve the ability to detect small molecules in recent years. This review focuses on the principles of detection platforms, classifies the conjugating methods between small molecules and aptamers, summarizes advancements in aptamer-based conjugate recognition techniques for the detection of small molecules in food, and seeks to provide emerging powerful tools in the field of point-of-care diagnostics.