d-/l-Isothymidine incorporation in the core sequence of aptamer BC15 enhanced its binding affinity to the hnRNP A1 protein

Diverse applications and development of aptamer detection technology

Aptamers have received extensive attention in recent years because of their advantages of high specificity, high sensitivity and low immunogenicity. Aptamers can perform almost all functions of antibodies through the combination of spatial structure and target, which are called "chemical antibodies". At present, aptamers have been widely used in cell imaging, new drug development, disease treatment, microbial detection and other fields. Due to the diversity of modifications, aptamers can be combined with different detection technologies to construct aptasensors. This review focuses on the diversity of aptamers in the field of detection and the development of aptamer-based detection technology and proposes new challenges for aptamers in this field.

Selective Anti-melanoma Effect of Phosphothioated Aptamer Encapsulated by Neutral Cytidinyl/Cationic Lipids

BC15-31 is a DNA aptamer that targets heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1), which plays a crucial role in the process of pre-RNA maturation and is also essential for the rapid proliferation of tumor cells. In this research, we modified BC15-31 with a phosphorothioate (PS) backbone, LNA, and 2-O-MOE to enhance its stability and target affinity. In addition, a neutral cytidinyl lipid (DNCA) and a cationic lipid (CLD) were mixed to encapsulate modified aptamers with the aim of improving their cell permeability with low toxicity. Under the DNCA/CLD package, aptamers are mainly distributed in the nucleus. A modified sequence WW-24 showed an excellent selective anti-melanoma (A375 cells, ∼25 nM, 80%) activity, targeted to both hnRNP A1 and hnRNP A2/B1 found by the BLI experiment, and induced more early and late apoptosis in vitro, which also showed stronger antitumor effect and longer accumulation time in vivo. These results provide a new strategy for further clinical applications.

A surface plasmon resonance biosensor in conjunction with a DNA aptamer-antibody bioreceptor pair for heterogeneous nuclear ribonucleoprotein A1 concentrations in colorectal cancer plasma solutions

A new DNA aptamer and antibody pair was incorporated into surface plasmon resonance (SPR) sensing platform to detect heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) in plasma at clinically relevant native concentrations for the diagnosis of colorectal cancer (CRC). SPR detection of hnRNP A1 was realized via formation of the surface sandwich complex of aptamer/hnRNP A1/anti-hnRNP A; the specific adsorption of hnRNP A1 onto a gold chip surface modified with a DNA aptamer followed by the adsorption of anti-hnRNP A1. Changes in the refractive unit (RU) with respect to the hnRNP A1 concentration in buffer solutions were monitored at a fixed anti-hnRNP A1 concentration of 90 nM, resulting in a dynamic range of 0.1-10 nM of hnRNP A1. The surface sandwich SPR biosensor was further applied to the direct analysis of undiluted human normal and pooled CRC patient plasma solutions. Our plasma analysis results were compared to those obtained with a commercial enzyme-linked immunosorbent assay kit.

A Bottom-Up Approach for Developing Aptasensors for Abused Drugs: Biosensors in Forensics

Aptamer-based point-of-care (POC) diagnostics platforms may be of substantial benefit in forensic analysis as they provide rapid, sensitive, user-friendly, and selective analysis tools for detection. Aptasensors have not yet been adapted commercially. However, the significance of the applications of aptasensors in the literature exceeded their potential. Herein, in this review, a bottom-up approach is followed to describe the aptasensor development and application procedure, starting from the synthesis of the corresponding aptamer sequence for the selected analyte to creating a smart surface for the sensitive detection of the molecule of interest. Optical and electrochemical biosensing platforms, which are designed with aptamers as recognition molecules, detecting abused drugs are critically reviewed, and existing and possible applications of different designs are discussed. Several potential disciplines in which aptamer-based biosensing technology can be of greatest value, including forensic drug analysis and biological evidence, are then highlighted to encourage researchers to focus on developing aptasensors in these specific areas.