Repurposing of thermally stable nucleic-acid aptamers for targeting tetrodotoxin (TTX)

Aptamer-Encapsulated Cellular Nanoparticles for Neurotoxin Neutralization

Aptamers are single-stranded oligonucleotides that fold into defined architectures for specific target binding. In this study, aptamers are selected that specifically bind to small-molecule neurotoxins and encapsulate them into cell membrane-coated nanoparticles (referred to as 'cellular nanoparticles' or 'CNPs') for effective neutralization of neurotoxins. Specifically, six different aptamers are selected that bind to saxitoxin (STX) or tetrodotoxin (TTX) and encapsulate them into metal-organic framework cores, which are then coated with neuronal cell membrane. The resulting CNPs exhibit high colloidal stability, minimal aptamer leakage, and effective protection of aptamer payloads against enzyme degradation. This detoxification platform combines membrane-enabled broad-spectrum neutralization with aptamer-based specific toxin binding, offering dual-modal neutralization mechanisms for efficient neurotoxin neutralization. The in vitro neutralization efficacy is demonstrated using a neuron osmotic swelling assay, a Na+ flux fluorescence assay, and a cytotoxicity assay. The in vivo neutralization efficacy is further validated using mouse models of STX and TTX intoxication in both therapeutic and preventative regimens. Overall, integrating aptamers with CNPs combines the strengths of both technologies, resulting in a robust solution for broad-spectrum toxin-neutralization applications.

Tetrodotoxin: The State-of-the-Art Progress in Characterization, Detection, Biosynthesis, and Transport Enrichment

Tetrodotoxin (TTX) is a neurotoxin that binds to sodium channels and blocks sodium conduction. Importantly, TTX has been increasingly detected in edible aquatic organisms. Because of this and the lack of specific antidotes, TTX poisoning is now a major threat to public health. However, it is of note that ultra-low dose TTX is an excellent analgesic with great medicinal value. These contradictory effects highlight the need for further research to elucidate the impacts and functional mechanisms of TTX. This review summarizes the latest research progress in relation to TTX sources, analogs, mechanisms of action, detection methods, poisoning symptoms, therapeutic options, biosynthesis pathways, and mechanisms of transport and accumulation in pufferfish. This review also provides a theoretical basis for reducing the poisoning risks associated with TTX and for establishing an effective system for its use and management to ensure the safety of fisheries and human health.

Tetrodotoxin and the state-of-the-art progress of its associated analytical methods

Tetrodotoxin (TTX), which is found in various marine organisms, including pufferfish, shellfish, shrimp, crab, marine gastropods, and gobies, is an effective marine toxin and the cause of many seafood poisoning incidents. Owing to its toxicity and threat to public health, the development of simple, rapid, and efficient analytical methods to detect TTX in various food matrices has garnered increasing interest worldwide. Herein, we reviewed the structure and properties, origin and sources, toxicity and poisoning, and relevant legislative measures of TTX. Additionally, we have mainly reviewed the state-of-the-art progress of analytical methods for TTX detection in the past five years, such as bioassays, immunoassays, instrumental analysis, and biosensors, and summarized their advantages and limitations. Furthermore, this review provides an in-depth discussion of the most advanced biosensors, including cell-based biosensors, immunosensors, and aptasensors. Overall, this study provides useful insights into the future development and wide application of biosensors for TTX detection.

Recent research progress in tetrodotoxin detection and quantitative analysis methods

Tetrodotoxin (TTX) is a highly potent and widely distributed ion-channel marine neurotoxin; it has no specific antidote and poses a great risk to human health. Therefore, detecting and quantifying TTX to effectively implement prevention strategies is important for food safety. The development of novel and highly sensitive, highly specific, rapid, and simple techniques for trace TTX detection has attracted widespread attention. This review summarizes the latest advances in the detection and quantitative analysis of TTX, covering detection methods based on biological and cellular sensors, immunoassays and immunosensors, aptamers, and liquid chromatography-mass spectrometry. It further discusses the advantages and applications of various detection technologies developed for TTX and focuses on the frontier areas and development directions of TTX detection, providing relevant information for further investigations.

Aptamer-modified paper-based analytical devices for the detection of food hazards: Emerging applications and future perspective

Food analysis plays a critical role in assessing human health risks and monitoring food quality and safety. Currently, there is a pressing need for a reliable, portable, and quick recognition element for point-of-care testing (POCT) to better serve the demands of on-site food analysis. Aptamer-modified paper-based analytical devices (Apt-PADs) have excellent characteristics of high portability, high sensitivity, high specificity, and on-site detection, which have been widely used and concerned in the field of food safety. The article reviews the basic components and working principles of Apt-PADs, and introduces their representative applications detecting food hazards. Finally, the advantages, challenges, and future directions of Apt-PADs-based sensing performance are discussed, to provide new directions and insights for researchers to select appropriate Apt-PADs according to specific applications.

Therapeutic Applications of Aptamers

Affinity reagents, or target-binding molecules, are quite versatile and are major workhorses in molecular biology and medicine. Antibodies are the most famous and frequently used type and they have been used for a wide range of applications, including laboratory techniques, diagnostics, and therapeutics. However, antibodies are not the only available affinity reagents and they do have significant drawbacks, including laborious and costly production. Aptamers are one potential alternative that have a variety of unique advantages. They are single stranded DNA or RNA molecules that can be selected for binding to many targets including proteins, carbohydrates, and small molecules-for which antibodies typically have low affinity. There are also a variety of cost-effective methods for producing and modifying nucleic acids in vitro without cells, whereas antibodies typically require cells or even whole animals. While there are also significant drawbacks to using aptamers in therapeutic applications, including low in vivo stability, aptamers have had success in clinical trials for treating a variety of diseases and two aptamer-based drugs have gained FDA approval. Aptamer development is still ongoing, which could lead to additional applications of aptamer therapeutics, including antitoxins, and combinatorial approaches with nanoparticles and other nucleic acid therapeutics that could improve efficacy.

Recent Advances in Aptasensing Strategies for Monitoring Phycotoxins: Promising for Food Safety

Phycotoxins or marine toxins cause massive harm to humans, livestock, and pets. Current strategies based on ordinary methods are long time-wise and require expert operators, and are not reliable for on-site and real-time use. Therefore, it is urgent to exploit new detection methods for marine toxins with high sensitivity and specificity, low detection limits, convenience, and high efficiency. Conversely, biosensors can distinguish poisons with less response time and higher selectivity than the common strategies. Aptamer-based biosensors (aptasensors) are potent for environmental monitoring, especially for on-site and real-time determination of marine toxins and freshwater microorganisms, and with a degree of superiority over other biosensors, making them worth considering. This article reviews the designed aptasensors based on the different strategies for detecting the various phycotoxins.

De novo design of DNA aptamers that target okadaic acid (OA) by docking-then-assembling of single nucleotides

Okadaic acid (OA) is a diarrhetic shellfish poison widespread in ocean, so its detection is of great significance to seafood safety. Because of good sensitivity and low cost, biosensors using nucleic-acid aptamers as the recognition molecules are emerging as an important detection tool. However, the traditional SELEX screening method for acquiring OA high-affinity aptamers is time- and resource-intensive. Alternatively, here we developed a de novo design method based on the 3D structure of a target molecule, such as OA. Without experimental screening, this method designs OA aptamers by a computational approach of docking-then-assembling (DTA) of single nucleotides (A, C, G and T) as: (1) determining the high-affinity nucleotide binding sites of the target molecule via saturated molecular docking; (2) assembling the bound nucleotides into binding units to the target molecule; (3) constructing full-length aptamers by introducing stabilizing units to connect these binding units. In this way, five OA aptamers were designed, and microscale thermophoresis (MST) experiments verified that their K_d values are in the range of 100-600 nM; and one of them (named 9CGAT_4_a) could specifically bind to OA with low affinities for the other three marine biotoxins. Therefore, this study provides high-affinity and specific aptamers for the development of OA biosensors, and presents a promising de novo design method applicable to other target molecules.