What is the nucleic acid aptamer?


Aptamer is a DNA (deoxyribonucleic acid), RNA (ribonucleic acid) sequence, XNA (nucleic acid analog) or peptide. The oligonucleotide fragments obtained from the nucleic acid molecule library are usually obtained by in vitro screening technology-Systematic evolution of ligands by exponential enrichment (SELEX).

Nucleic acid aptamer application
Aptamers can bind to a variety of target substances with high specificity and selectivity, so they are widely used in the field of biosensors. When the aptamer specifically binds to the target substance, the configuration of the aptamer itself will change accordingly. Researchers applied nucleic acid aptamers to probes and developed many electrochemical sensors based on the configurational changes of nucleic acid aptamers, also known as E-AB (Electrochemical aptamer-based) sensors, which combined with electrochemical detection methods. It has the characteristics of portability, simple operation and low cost, so the E-AB sensor improves the application of nucleic acid aptamers in the field of sensors.
In addition, it can be used for colorimetric detection of trace lead ions in solution with a detection limit of 500nM.

Nucleic acid aptamer advantage
The traditional antigen-antibody reaction has good sensitivity and specificity. ELISA plays a pivotal role in the detection of various biomolecules. Many kits on the market are developed based on this principle. However, as probe molecules, proteins are easily denatured by environmental factors such as pH and temperature, and are expensive to synthesize. Aptamers are composed of DNA or RNA (mainly DNA) and are smaller than proteins. After screening and enrichment by SELEX , can have sensitivity comparable to antigen-antibody reaction, while being easier to synthesize and better stability. In the near future, aptamers are expected to replace the enzyme-linked immune reaction and become a powerful weapon for the detection of various chemical molecules.

Introduction to Nucleic Acid Aptamers
Deoxyribonucleic acid (DNA) is a molecule that encodes the genetic instructions used in the development and functioning of all known organisms and many viruses. DNA is a nucleic acid, and nucleic acids, together with proteins and carbohydrates, constitute the three macromolecules necessary for all known life forms. Most DNA molecules consist of two biopolymer strands coiled around each other to form a double helix. Each nucleotide consists of a rheological nucleobase—either guanine (G), adenine (A), thymine (T), and cytosine (C)—sugars also known as deoxyribose and phosphate-based monosaccharides . The chains of nucleotides are linked to each other by covalent bonds of the sugar nucleotide phosphates, resulting in an alternan phosphate backbone. According to the base pairing rules (A and T, C and G), hydrogen-bonded nitrogenous bases are two independent polynucleotide strands of double-stranded DNA.
DNA is suitable for biological information storage. The DNA backbone is crack-resistant, two strands of double-stranded structure that store the same biological information. The two strands of biological information replication are separate. A large portion of human (over 98%) noncoding DNA means that these portions do not serve as protein sequence patterns.
The two strands of DNA run in opposite directions and are therefore anti-parallel. Attached to each sugar is one of four types of bases (informal bases). It is the backbone of the biological information encoded by the sequence of these four bases. According to the genetic code, RNA strands switch designated amino acids in the protein sequence. These RNA strands are initially created using a DNA strand as a template in a process called transcription.

DNA inside cells is organized into long structures called chromosomes. Chromosomes provide each cell with its own complete chromosomes during cell division during these repeated DNA replications. Most of the eukaryotic (animal, plant, fungal, and protist) libraries contain DNA in the nucleus and DNA organelles, such as mitochondria and chloroplasts. In contrast, prokaryotes (bacteria and archaea) store DNA only in the cytoplasm. In chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide interactions between DNA and other proteins, helping to control which parts of DNA are transcribed.
Scientists use DNA molecular tools to explore physical laws and theories, such as the ergodic theorem and elasticity theory. The unique material properties of DNA make it an attractive molecular material for scientists and engineers interested in micro- and nano-fabrication. Significant advances in this field are DNA origami and DNA hybrid materials.