Electrochemical DNA Biosensors with Dual-Signal Amplification Strategy for Highly Sensitive HPV 16 Detection.

Cervical cancer is an important topic in the study of global health issues, ranking fourth among women's cancer cases in the world. It is one of the nine major cancers that China is focusing on preventing and treating, and it is the only cancer that can be prevented through vaccination. Systematic and effective screening for human papilloma (HPV) infection, which is closely linked to the development of cervical cancer, can reduce cervical cancer incidence and mortality. In this paper, an electrochemical sensor was designed to detect HPV 16 using dual-signal amplification. An APTES-modified glassy carbon electrode was used for improved stability. Gold nanoparticles and a chain amplification reaction were combined for signal amplification. The limit of detection (LOD) of this electrochemical sensor was 1.731 × 10-16 mol/L, and the linear response of the target detector range was from 1.0 × 10-13 mol/L to 1.0 × 10-5 mol/L (R2 = 0.99232). The test of serum sample recovery showed that it has good anti-interference, and the performance of all aspects was improved to different degrees compared with the previous research from the team. The designed sensor is centered around the principles of low cost, high sensitivity and stability, which provides new ideas for the future development of cervical cancer prevention and electrochemical biosensors.

Enzyme-Assisted Amplification and Copper Nanocluster Fluorescence Signal-Based Method for miRNA-122 Detection.

At present, a large number of studies have demonstrated that miRNAs can be used as biological indicators for the diagnosis and treatment of diseases such as tumours and cancer, so it is important to develop a new miRNA detection platform. In this work, miRNA-122 is used as the basis for targeting detection agents. We have designed an unlabelled DNA1 that undergoes partial hybridisation and has a 20 T base long strand. The fluorescent signal in this experiment is derived from copper nanoclusters (CuNCs) generated on the circular T-long strand of DNA1. At the same time, DNA1 is able to react with miRNA-122 and achieve hydrolysis of the part bound to miRNA-122 via the action of nucleic acid exonuclease III (Exo III), leaving a part of the DNA, called DNA3, while releasing miRNA-122 to participate in the next reaction, thus achieving circular amplification. DNA3 is able to react with DNA2, which is bound to streptavidin magnetic beads (SIBs) and separated from the reaction solution via the application of a magnetic field. Overall, this is a fluorescence signal reduction experiment, and the strength of the fluorescence signal from the copper nanoclusters can determine whether the target miRNA-122 is present or not. The degree of fluorescence reduction indicates how much DNA1, and thus the amount of target miRNA-122, has been hydrolysed. By evaluating the variations in the fluorescence signal under optimised conditions, we discovered that this method has good sensitivity, with a detection limit as low as 0.46 nM, better than many other previous works on fluorescence signal-based biosensors for miRNA detection. This technique offers high discrimination and selectivity and can serve as a persuasive reference for early diagnosis.

Gold Nanoparticle-Based Enzyme-Assisted Cyclic Amplification for the Highly-Sensitive Detection of miRNA-21.

Because microRNAs (miRNAs) are biological indicators for the diagnosis, treatment, and monitoring of tumors, cancers, and other diseases, it is significant to develop a rapid, sensitive, and reliable miRNA detection platform. In this study, based on miRNA-21 detection, DNA-a with a 3' end overhang and Texas Red fluorophore-labeled 5' end was designed, which reacts with miRNA-21 and hybridizes with exonuclease III (Exo III), where the part connected to miRNA-21 is hydrolyzed, leaving a-DNA. At the same time, miRNA-21 is released to participate in the following reaction, to achieve cyclic amplification. a-DNA reacts with DNA-b conjugated to gold nanoparticles to achieve fluorescence quenching, with the quenching value denoted as F; additionally, after adding DNA-d and linked streptavidin immunomagnetic beads (SIBs), fluorescence recovery was achieved using DNA-c, with the recovered fluorescence recorded as F0. By comparing the difference in the fluorescence (F0 - F) between the two experiments, the amount of DNA-a hydrolyzed to produce a-DNA was established to determine the target miRNA-21 content. Under optimized conditions, by comparing the changes in the fluorescence signal, the developed strategy shows good sensitivity and repeatability, with a detection limit of 18 pM, good discriminative ability and selectivity, and promise for the early diagnosis of breast and intestinal cancers.

APTES-Modified Remote Self-Assembled DNA-Based Electrochemical Biosensor for Human Papillomavirus DNA Detection.

High-risk human papillomavirus (HPV) infection is an important cause of cervical cancer formation; therefore, being able to detect high-risk HPV (e.g., HPV-16) is important for the early treatment and prevention of cervical cancer. In this study, a combination of a 3-aminopropyltriethoxysilane (APTES) modified gold electrode and a super sandwich structure was creatively developed, resulting in the development of a biosensor that is both sensitive and stable for the detection of HPV-16. The electrochemical biosensor possesses a lower detection limit compared with previous studies with an LOD of 5.475 × 10-16 mol/L and it possesses a wide linear range from 1.0 × 10-13 mol/L to 1.0 × 10-6 mol/L (R2 = 0.9923) for the target DNA. The experimental data show that the sensor has good stability, and there is no significant decrease in the current response value after 7 days in the low-temperature environment. In addition, the sensor proved to be a powerful clinical tool for disease diagnosis because it showed good interference resistance in complex human serum samples.