Aptamers are single-stranded oligonucleotide ligands selected from a random pool of oligonucleotide sequences by systematic evolution of ligands by exponential enrichment. With the advantages of binding to targets with high specificity and affinity, aptamers have been used in the diagnosis widely, such as biochemistry detection, discovery of new tumor markers, molecular imaging, pathogenic and microorganism detection, showing a good application prospect.
Aptamers, Nucleotide ; Diagnosis ; Disease ; Humans ; Sensitivity and Specificity

Targeting of complex system such as human cells rather than biochemically pure molecules will be a useful approach to massively identify ligands specific for the markers associated with human disease such as cancer and simultaneously discover the specific molecular markers. In this study, we developed in vitro selection method to identify nuclease-resistant nucleic acid ligands called RNA aptamers that are specific for human cancer cells. This method is based on the combination of the cell-based selection and subtractive systematic evolution of ligands by exponential enrichment (SELEX) method. These aptamers will be useful for cancer-specific ligands for proteomic research to identify cancer-specific molecular markers as well as tumor diagnosis and therapy.
Aptamers, Nucleotide ; Diagnosis ; Humans ; Ligands* ; Proteomics ; SELEX Aptamer Technique

The computer information technology that has penetrated into every aspect of our lives, can not only assist the screening of drugs, but also simulate the effect of drugs. At present, computer-aided technologies have been used to screen aptamers, which play an important role in improving the screening efficiency and screening high affinity binding aptamers. This review summarized the screening methods of aptamers through computer-aided sequence evaluation, structural analysis and molecular docking.
Aptamers, Nucleotide ; Computers ; Molecular Docking Simulation ; SELEX Aptamer Technique/methods*

Molecular imaging technology, an advanced research area of imaging, can provide real-time, non-invasive image information of the target site in molecular level. The key of the molecular imaging technology is molecular probe. Aptamers are short oligonucleotides with high affinity and specificity to the target molecules. The targeting ability, stability and safety of aptamers are superior to traditional antibodies so that aptamers show prosperous usages in targeting drug delivery and disease diagnostics. Therefore, aptamers are considered to be an extremely ideal probes, which can guide quantum dots, magnetic nanoparticles and ultrasound contrast agents on the targets and realize optical, magnetic resonance, ultrasonic multimodal and multifunctional imaging. All of the advantages can further promote the application of molecular imaging in disease treatment and diagnosis. In this paper, we review recent developments in the application of aptamers as molecular probes in major branches of molecular imaging.
Animals ; Aptamers, Nucleotide ; Contrast Media ; Humans ; Molecular Imaging ; methods ; trends ; Molecular Probes ; SELEX Aptamer Technique

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 ; Aptamers, Nucleotide ; isolation & purification ; Biosensing Techniques ; methods ; Drug Design ; Humans ; Nanotechnology ; methods ; SELEX Aptamer Technique

Aptamers are a group of artificial oligonucleotides identified by exponential enrichment system evolution technology (Selective expansion of ligands by exponential enrichment, SELEX). Aptamers have been widely used in basic research, clinical diagnostics, and nano-technology. In this article we will introduce the technology of aptamer and summarize its applications in medical microbiology.
Aptamers, Nucleotide ; biosynthesis ; genetics ; Microbiological Techniques ; methods ; Microbiology ; SELEX Aptamer Technique ; methods ; trends

Molecular imaging has greatly advanced basic biology and translational medicine through visualization and quantification of single/multiple molecular events temporally and spatially in a cellular context and in living organisms. Aptamers, short single-stranded nucleic acids selected in vitro to bind a broad range of target molecules avidly and specifically, are ideal molecular recognition elements for probe development in molecular imaging. This review summarizes the current state of aptamer-based biosensor development (probe design and imaging modalities) and their application in imaging small molecules, nucleic acids and proteins mostly in a cellular context with some animal studies. The article is concluded with a brief discussion on the perspective of aptamer-based molecular imaging.
Animals ; Aptamers, Nucleotide ; genetics ; metabolism ; Base Sequence ; Biosensing Techniques ; Humans ; Molecular Imaging ; methods

Nucleic acid aptamers, broad-spectrum target-specific single-stranded oligonucleotides, serve as molecules in targeted therapy, targeted delivery and disease diagnosis for the treatment of tumor or microbial infection and clinical detection. Due to the existence of components in the use of traditional Chinese medicine(TCM), the target is difficult to concentrate and the specificity of treatment is poor. The effective components of TCM are toxic components, so a highly sensitive detection method is urgently needed to reduce the toxicity problem at the same time. The combined application of TCM and modern medical treatment strategy are difficult and cannot improve the therapeutic effect. Aptamers, advantageous in biosensors, aptamer-nanoparticles for targeted drug delivery, and aptamer-siRNA chimeras, are expected to connect Chinese medicinals with nanotechnology, diagnostic technology and combined therapies. We summarized the preparation, screening, and modification techniques of nucleic acid aptamers and the biomedical applications and advantages in therapy, targeting, and diagnosis, aiming at providing a reference for the in-depth research and development in TCM.
Aptamers, Nucleotide ; Drug Delivery Systems ; Medicine, Chinese Traditional ; Nucleic Acids ; RNA, Small Interfering

RNA therapeutics inhibit the expression of specific proteins/RNAs by targeting complementary sequences of corresponding genes or encode proteins for the synthesis desired genes to treat genetic diseases. RNA-based therapeutics are categorized as oligonucleotide drugs (antisense oligonucleotides, small interfering RNA, RNA aptamers), and mRNA drugs. The antisense oligonucleotides and small interfering RNA for treatment of genetic diseases have been approved by the FDA in the United States, while RNA aptamers and mRNA drugs are still in clinical trials. Chemical modifications can be applied to RNA drugs, such as pseudouridine modification of mRNA, to reduce immunogenicity and improve the efficacy. The secure and effective delivery systems such as lipid-based nanoparticles, extracellular vesicles, and virus-like particles are under development to address stability, specificity, and safety issues of RNA drugs. This article provides an overview of the specific molecular mechanisms of eleven RNA drugs currently used for treating genetic diseases, and discusses the research progress of chemical modifications and delivery systems of RNA drugs.
Aptamers, Nucleotide ; RNA, Small Interfering/therapeutic use* ; RNA, Messenger ; Oligonucleotides, Antisense/therapeutic use*

RNA-binding protein exerts important biological function by specifically recognizing RNA motif. SELEX (Systematic evolution of ligands by exponential enrichment), an in vitro selection method, can obtain consensus motif with high-affinity and specificity for many target molecules from DNA or RNA libraries. Here, we combined SELEX with next-generation sequencing to study the protein-RNA interaction in vitro. A pool of RNAs with 20 bp random sequences were transcribed by T7 promoter, and target protein was inserted into plasmid containing SBP-tag, which can be captured by streptavidin beads. Through only one cycle, the specific RNA motif can be obtained, which dramatically improved the selection efficiency. Using this method, we found that human hnRNP A1 RRMs domain (UP1 domain) bound RNA motifs containing AGG and AG sequences. The EMSA experiment indicated that hnRNP A1 RRMs could bind the obtained RNA motif. Taken together, this method provides a rapid and effective method to study the RNA binding specificity of proteins.
Aptamers, Nucleotide ; Gene Library ; Heterogeneous Nuclear Ribonucleoprotein A1 ; genetics ; High-Throughput Nucleotide Sequencing ; Humans ; RNA ; SELEX Aptamer Technique