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Nucleic Acid Adapter Screening Service

TekBiotech is committed to providing customers with high-affinity and high-specificity nucleic acid aptamer screening technology services, and providing strong support for customers' subsequent aptamer function verification (including affinity verification, competitive ELISA verification, in vitro targeted cell functional verification (for example: nucleic acid aptamer in vitro recognition and inhibition function verification, in vitro flow blocking function, etc.), in vivo functional verification (for example: aptamer in vivo targeted inhibition function verification, signal pathway blocking function verification, etc.)) and the development of targeted specific molecular drugs and other downstream R&D work. TekBiotech has many years of project experience and experience in nucleic acid aptamer screening (SELEX technology). After years of development, TekBiotech has established a complete nucleic acid aptamer screening system, which can provide customers with high-quality nucleic acid aptamer (including RNA aptamer and DNA aptamer) screening services for targets including but not limited to proteins, peptides, amino acids, small molecule compounds, etc.

█ Nucleic Acid Aptamer Development Technology Service (SELEX Screening Technology Service)

Nucleic acid aptamer screening refers to the principle of systematic evolution of ligands by exponential enrichment (SELEX), which binds the screening target to the surface of the screening solid phase particles, and obtains the target oligonucleotide fragment (DNA fragment or RNA fragment) from the nucleic acid aptamer library through incubation, washing and amplification with the nucleic acid aptamer library.

The nucleic acid aptamer library established by TekBiotech has a capacity of 10^14, which is sufficient to screen nucleic acid aptamers for various targets and meet the downstream experimental needs of customers. The affinity of candidate aptamer sequences can reach nM-pM level.

TekBiotech can provide a variety of antigen screening (including but not limited to proteins, peptides, amino acids, small molecules, etc.), and a variety of aptamer screening methods (for example: liquid phase SELEX, cell SELEX, etc.), and the commonly used screening method is magnetic bead screening. For special samples, the screening method will be different. For example, small drug molecules need to screen aptamers, which often require small molecule modification technology. The scientists of TekBiotech will evaluate the customer's project needs and design the best solution for antigen modification and aptamer screening. The nucleic acid aptamer screening process is shown in Figure 1:

Nucleic acid aptamer screening service-tekbiotech1.png

Figure 1 Nucleic acid aptamer screening process (typical procedure of SELEX method)

TekBiotech can also provide a variety of downstream verification experiments including but not limited to nucleic acid aptamer affinity verification (including BLI affinity verification and SPR affinity verification), competitive ELISA verification, flow blocking verification, etc. Customers only need to provide screening targets and project requirements. The scientists of TekBiotech provide reasonable customized solutions based on the customer's project needs to solve the customer's scientific research problems.

█ Types of Nucleic Acid Aptamer Development Technology Services (SELEX Screening Technology Services)

TekBiotech has accumulated a lot of project experience in nucleic acid aptamer screening for conventional proteins, peptides, cells and small molecules of modifiable organic compounds. According to customer needs, we will summarize and summarize the following types of nucleic acid aptamer screening, as shown in Table 1:

Protein Nucleic Acid Aptamer Screening Service	Small Molecule Nucleic Acid Aptamer Screening Service
Metal Ion Nucleic Acid Aptamer Screening Service	Cell Nucleic Acid Aptamer Screening Service

█ Content and cycle of Nucleic Acid Aptamer Screening Service

Steps

Service Content

Cycle

Step1: Nucleic acid aptamer screening

1) The customer provides screening target information, and TekBiotech performs project evaluation and modification

(conventional modification: biotin modification);

2) Library enrichment and screening: 6-10 rounds of screening, SA magnetic bead negative screening; NGS sequencing;

3) Delivery: 10-50 aptamer sequences, including frequency of occurrence; experimental report;

8-12 Weeks

Step 2: Aptamer synthesis and

affinity determination

1) Synthesize biotin-labeled aptamers (design and synthesize according to specific circumstances);

2) Rapid affinity determination of aptamers and targets (affinity ranking);

3) Delivery: synthesis report, affinity determination experimental report, raw data;

3-4 Weeks

█ Advantages of Nucleic Acid Aptamer Screening Service


A variety of screening targets are available: proteins, peptides, amino acids, small molecules	Large library capacity, high project success rate	Mature SELEX technology platform: the affinity of the nucleic acid aptamers obtained by screening can reach nM-pM level	Rich supporting downstream verification experiments: affinity verification (including BLI and SPR affinity verification), competitive ELISA verification, flow blocking verification, etc.

Experimental records are traceable: Chinese and English experimental reports, original experimental records	One-to-one personalized solution customization to meet the scientific research project needs of various customers	6-10 rounds of pressure screening, can obtain high-affinity and high-specificity nucleic acid aptamers	Multiple screening methods: magnetic beads-SELEX, cell-SELEX, capture- SELEX, etc.

Nucleic Acid Adapter Screening Service Frequently Asked Questions

What are aptamers? How do they differ from antibodies?

Aptamers are a class of short-chain nucleic acid molecules that can specifically bind to specific target molecules (such as proteins, small molecules, viruses, etc.), usually composed of single-stranded DNA or RNA. Unlike traditional antibodies, aptamers are obtained by in vitro selection and screening rather than by immune response. They have similar specificity and affinity to antibodies, but compared to antibodies, aptamers have some unique advantages. For example, aptamers can be quickly prepared by chemical synthesis, are not restricted by animal ethics issues, and are obtained at lower costs and simpler operations. In addition, aptamers can also maintain stability under extreme conditions, such as high temperature or extreme pH conditions, while antibodies are prone to denaturation. Therefore, aptamers have broad application prospects in biomarker detection, drug development, targeted therapy, etc.
What are the common methods for aptamer screening?

Aptamers are usually screened using in vitro screening technology, the most common of which is "systematic evolution of ligand enzyme-linked immunosorbent assay" (SELEX). SELEX is a method of in vitro selection to screen aptamers that bind to specific targets. The basic steps include: first synthesizing a random sequence containing a diverse library (usually a nucleic acid library with 10^13 to 10^15 different sequences); then exposing the library to the target molecule, and retaining those sequences that can bind to the target after binding, washing and elution steps; then, amplifying these retained aptamers by PCR and performing the next round of screening. A significant advantage of SELEX is that it can improve the affinity and specificity between aptamers and targets through continuous iterative screening. In addition to the traditional SELEX method, there are some improved SELEX technologies, such as nanopore SELEX, liquid phase SELEX, microarray SELEX, etc., which can improve screening efficiency and specificity to meet different application requirements.
How to evaluate the affinity of aptamers during nucleic acid aptamer screening?

In the process of nucleic acid aptamer screening, evaluating the affinity between aptamers and targets is a key step. The affinity of aptamers is usually evaluated by measuring their binding kinetics. Common techniques include surface plasmon resonance (SPR), isothermal titration calorimetry (ITC), and fluorescence resonance energy transfer (FRET). These techniques can provide detailed information about antigen-aptamer binding, such as association rate (ka), dissociation rate (kd), and dissociation constant (Kd). Among them, SPR technology is widely used in affinity determination because it can monitor the interaction between aptamers and targets in real time, without labeling reactants, and can be screened in high throughput under different conditions. In addition, by combining technologies such as ELISA and affinity electrophoresis, researchers can also detect changes in the affinity of aptamers and targets in real time during the screening process, thereby optimizing the screening strategy and screening out aptamers with higher affinity.
How to deal with high variability in the diversity library during nucleic acid aptamer screening?

The screening of nucleic acid aptamers usually starts with a random sequence library containing extremely high variability, which makes the affinity and specificity of each aptamer sequence vary greatly. In screening techniques such as SELEX (systematically evolved ligand enzyme-linked immunosorbent assay), the diversity of the library often determines the effectiveness and success rate of the screening. To cope with this diversity, the screening process gradually "enriches" the aptamers that bind most tightly to the target through multiple rounds of selection. Each round of selection will eliminate those sequences with low affinity and ineffective binding to the target, leaving the strongest binders. As the number of screening rounds increases, the affinity and specificity of the aptamer will gradually increase. In addition, the interaction between the aptamer and the target can be enhanced by optimizing the screening conditions (such as increasing the elution intensity, changing the temperature and pH value). Through multiple rounds of enrichment and refined screening steps, nucleic acid aptamers with very high specificity and affinity can be screened from a highly diverse library.
How to evaluate the specificity of the selected nucleic acid aptamers?

In the process of nucleic acid aptamer screening, evaluating the specificity of the aptamer is a key step to ensure its effectiveness in practical applications. Usually, the specificity of the aptamer to the target is verified by multiple methods. For example, affinity chromatography, competitive binding experiments, or ELISA techniques can be used to detect whether the aptamer only binds to the target molecule and does not cross-react with non-target molecules. In the specificity assessment, competitive binding experiments are particularly important. By competing with known antigen binders, it is confirmed whether the nucleic acid aptamer selectively binds to the target rather than other similar molecules. In addition, high-throughput screening technologies (such as microarrays, flow cytometry, etc.) can also be used to detect the reaction of aptamers with multiple targets in a larger range, thereby further confirming the selectivity of the aptamer. For aptamers with high specificity, they can usually only bind to specific targets, and the binding constant (Kd) is small, and they do not non-specifically bind to other molecules. Therefore, comprehensive specificity detection and verification is an important part of the screening process that cannot be ignored.

What are aptamers? How do they differ from antibodies?

Aptamers are a class of short-chain nucleic acid molecules that can specifically bind to specific target molecules (such as proteins, small molecules, viruses, etc.), usually composed of single-stranded DNA or RNA. Unlike traditional antibodies, aptamers are obtained by in vitro selection and screening rather than by immune response. They have similar specificity and affinity to antibodies, but compared to antibodies, aptamers have some unique advantages. For example, aptamers can be quickly prepared by chemical synthesis, are not restricted by animal ethics issues, and are obtained at lower costs and simpler operations. In addition, aptamers can also maintain stability under extreme conditions, such as high temperature or extreme pH conditions, while antibodies are prone to denaturation. Therefore, aptamers have broad application prospects in biomarker detection, drug development, targeted therapy, etc.
What are the common methods for aptamer screening?

Aptamers are usually screened using in vitro screening technology, the most common of which is "systematic evolution of ligand enzyme-linked immunosorbent assay" (SELEX). SELEX is a method of in vitro selection to screen aptamers that bind to specific targets. The basic steps include: first synthesizing a random sequence containing a diverse library (usually a nucleic acid library with 10^13 to 10^15 different sequences); then exposing the library to the target molecule, and retaining those sequences that can bind to the target after binding, washing and elution steps; then, amplifying these retained aptamers by PCR and performing the next round of screening. A significant advantage of SELEX is that it can improve the affinity and specificity between aptamers and targets through continuous iterative screening. In addition to the traditional SELEX method, there are some improved SELEX technologies, such as nanopore SELEX, liquid phase SELEX, microarray SELEX, etc., which can improve screening efficiency and specificity to meet different application requirements.
How to evaluate the affinity of aptamers during nucleic acid aptamer screening?

In the process of nucleic acid aptamer screening, evaluating the affinity between aptamers and targets is a key step. The affinity of aptamers is usually evaluated by measuring their binding kinetics. Common techniques include surface plasmon resonance (SPR), isothermal titration calorimetry (ITC), and fluorescence resonance energy transfer (FRET). These techniques can provide detailed information about antigen-aptamer binding, such as association rate (ka), dissociation rate (kd), and dissociation constant (Kd). Among them, SPR technology is widely used in affinity determination because it can monitor the interaction between aptamers and targets in real time, without labeling reactants, and can be screened in high throughput under different conditions. In addition, by combining technologies such as ELISA and affinity electrophoresis, researchers can also detect changes in the affinity of aptamers and targets in real time during the screening process, thereby optimizing the screening strategy and screening out aptamers with higher affinity.
How to deal with high variability in the diversity library during nucleic acid aptamer screening?

The screening of nucleic acid aptamers usually starts with a random sequence library containing extremely high variability, which makes the affinity and specificity of each aptamer sequence vary greatly. In screening techniques such as SELEX (systematically evolved ligand enzyme-linked immunosorbent assay), the diversity of the library often determines the effectiveness and success rate of the screening. To cope with this diversity, the screening process gradually "enriches" the aptamers that bind most tightly to the target through multiple rounds of selection. Each round of selection will eliminate those sequences with low affinity and ineffective binding to the target, leaving the strongest binders. As the number of screening rounds increases, the affinity and specificity of the aptamer will gradually increase. In addition, the interaction between the aptamer and the target can be enhanced by optimizing the screening conditions (such as increasing the elution intensity, changing the temperature and pH value). Through multiple rounds of enrichment and refined screening steps, nucleic acid aptamers with very high specificity and affinity can be screened from a highly diverse library.
How to evaluate the specificity of the selected nucleic acid aptamers?

In the process of nucleic acid aptamer screening, evaluating the specificity of the aptamer is a key step to ensure its effectiveness in practical applications. Usually, the specificity of the aptamer to the target is verified by multiple methods. For example, affinity chromatography, competitive binding experiments, or ELISA techniques can be used to detect whether the aptamer only binds to the target molecule and does not cross-react with non-target molecules. In the specificity assessment, competitive binding experiments are particularly important. By competing with known antigen binders, it is confirmed whether the nucleic acid aptamer selectively binds to the target rather than other similar molecules. In addition, high-throughput screening technologies (such as microarrays, flow cytometry, etc.) can also be used to detect the reaction of aptamers with multiple targets in a larger range, thereby further confirming the selectivity of the aptamer. For aptamers with high specificity, they can usually only bind to specific targets, and the binding constant (Kd) is small, and they do not non-specifically bind to other molecules. Therefore, comprehensive specificity detection and verification is an important part of the screening process that cannot be ignored.

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