An amplification strategy for detecting HER2 with a quasi-targeted proteomics approach coupled with aptamer-triggered hybridization chain reaction

A novel electrochemical biosensor based on AMNFs@ZIF-67 nano composite material for ultrasensitive detection of HER2

Antimonene (AMNFs) is a new kind of sp²-bonded honeycomb lattice two-dimensional material with strong rod-rail coupling, stability and hydrophilicity. Compared with graphene, antimonene has better sensitivity in DNA molecular sensing. We developed a suitable biosensor-Cd²⁺-aptamer@AMNFs@ZIF-67 nanocomposite for HER2 biomarker detection. Two-dimensional antimonene can be grown on the surface of ZIF-67 to enhance stability and biocompatibility. The aptamer chain can also be adsorbed on the surface of antimonene, and the complexes of the aptamer and the marker can be detached analytically after targeting the biomarker. The detection limit (LOD) was 4.853 fg/mL within 60 min, the detection range was 0-1000 pg/mL, and the LOD was lower than the existing HER2 aptamer biosensors. The results show that the biosensor has certain applicability and potential, and is expected to be a powerful tool for breast cancer diagnosis in the future.

An ultrasensitive dual-signal ratio electrochemical aptamer biosensor for the detection of HER2

Electrochemical ratiometric biosensors have received attention from researchers because of their self-calibration capability, which can improve the accuracy of detection. In the present study, a ratiometric dual signal electrochemical aptamer biosensor based on ZIF-67 @polydopamine (PDA) nanocomposite and Cu/UiO-66 @ 3, 3', 5, 5'-tetramethylbenzidine (TMB) nanocomposite was fabricated for the detection of breast cancer biomarker- human epidermal growth factor receptor 2 (HER2). PDA was chosen as the electroactive material with electrochemical redox activity and ZIF-67 with a high specific surface area, forming the ZIF-67 @PDA+Apt as the nanoprobe for capturing HER2 in this paper. Cu/UiO-66 is a bimetallic compound with high stability, specific surface area, and strong adsorption onto aptamer chains, and the Cu/UiO-66 @TMB+Apt nanocomposite was used as a probe for signal labeling. In the presence of HER2, the capture of HER2 by the ZIF-67 @PDA+Apt probe results in a weakening of the conductivity of the electrode, however, by attenuating the electrochemical signal from the PDA, altering the probe-Cu/UiO-66 @TMB+Apt signaling will result in the enhancement of the TMB electrochemical signal. With a sensitive detection of HER2 biomarkers in as little as 30 min with the detection range of 0.75-40 pg/mL and a limit of detection as low as 44.8 fg/mL. Dual signal ratio biosensors have a low limit of detection, short detection time, which can accurately detect targets in complex biological samples, which has important theoretical importance.

Aptamer-Based Probes for Cancer Diagnostics and Treatment

Aptamers are single-stranded DNA or RNA oligomers that have the ability to generate unique and diverse tertiary structures that bind to cognate molecules with high specificity. In recent years, aptamer researches have witnessed a huge surge, owing to its unique properties, such as high specificity and binding affinity, low immunogenicity and toxicity, and simplicity of synthesis with negligible batch-to-batch variation. Aptamers may bind to targets, such as various cancer biomarkers, making them applicable for a wide range of cancer diagnosis and treatment. In cancer diagnostic applications, aptamers are used as molecular probes instead of antibodies. They have the potential to detect various cancer-associated biomarkers. For cancer therapeutic purposes, aptamers can serve as therapeutic or delivery agents. The chemical stabilization and modification strategies for aptamers may expand their serum half-life and shelf life. However, aptamer-based probes for cancer diagnosis and therapy still face several challenges for successful clinical translation. A deeper understanding of nucleic acid chemistry, tissue distribution, and pharmacokinetics is required in the development of aptamer-based probes. This review summarizes their application in cancer diagnostics and treatments based on different localization of target biomarkers, as well as current challenges and future prospects.

Optimizing the hybridization chain reaction-fluorescence in situ hybridization (HCR-FISH) protocol for detection of microbes in sediments

Fluorescence in situ hybridization (FISH) is a canonical tool commonly used in environmental microbiology research to visualize targeted cells. However, the problems of low signal intensity and false-positive signals impede its widespread application. Alternatively, the signal intensity can be amplified by incorporating Hybridization Chain Reaction (HCR) with FISH, while the specificity can be improved through protocol modification and proper counterstaining. Here we optimized the HCR-FISH protocol for studying microbes in environmental samples, particularly marine sediments. Firstly, five sets of HCR initiator/amplifier pairs were tested on the laboratory-cultured bacterium Escherichia coli and the archaeon Methanococcoides methylutens, and two sets displayed high hybridization efficiency and specificity. Secondly, we tried to find the best combination of sample pretreatment methods and HCR-FISH protocol for environmental sample analysis with the aim of producing less false positive signals. Various detachment methods, extraction methods and formulas of hybridization buffer were tested using sediment samples. Thirdly, an image processing method was developed to enhance the DAPI signal of microbial cells against that of abiotic particles, providing a reliable reference for FISH imaging. In summary, our optimized HCR-FISH protocol showed promise to serve as an addendum to traditional FISH for research on environmental microbes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42995-021-00098-8.