Polythiophene derivative on quartz resonators for miRNA capture and assay

Simultaneous Detection of Exosomal microRNAs Isolated from Cancer Cells Using Surface Acoustic Wave Sensor Array with High Sensitivity and Reproducibility

We present a surface acoustic wave (SAW) sensor array for microRNA (miRNA) detection that utilizes photocatalytic silver staining on titanium dioxide (TiO2) nanoparticles as a signal enhancement technique for high sensitivity with an internal reference sensor for high reproducibility. A sandwich hybridization was performed on working sensors of the SAW sensor array that could simultaneously capture and detect three miRNAs (miRNA-21, miRNA-106b, and miRNA-155) known to be upregulated in cancer. Sensor responses due to signal amplification varied depending on the concentration of synthetic miRNAs. It was confirmed that normalization (a ratio of working sensor response to reference sensor response) screened out background interferences by manipulating data and minimized non-uniformity in the photocatalytic silver staining step by suppressing disturbances to both working sensor signal and reference sensor signal. Finally, we were able to successfully detect target miRNAs in cancer cell-derived exosomal miRNAs with performance comparable to the detection of synthetic miRNAs.

Sensitive detection of microRNA using QCM biosensors: sandwich hybridization and signal amplification by TiO2 nanoparticles

MicroRNA-21 (miR-21) is known to act as an important biomarker for cancer, in that its up-regulation is closely related to several types of malignant tumor. Sensitive and accurate detection of miR-21 using a biosensor is highly challenging. In this study, sensitive and selective detection technology for miR-21 molecules using a quartz crystal microbalance (QCM) biosensor was developed. Sandwich hybridization between miR-21 and specially designed probes and a subsequent TiO2 photocatalytic silver enhancement reaction were the driving forces for sensitive detection with high selectivity for miR-21. Using this strategic approach under optimal conditions, the novel QCM biosensor can detect miR-21 with a LOD of 0.87 pM over the entire linear range from 0.1 pM to 10 μM, with a correlation coefficient of 0.988. In addition, the developed QCM biosensor was very effective in the quantification of miR-21 in serum samples, so the proposed miRNA detection method offers great potential for the diagnosis of early disease, such as cancer and vascular diseases, and could be an excellent alternative for biological research and clinical diagnosis.

PNA-Based MicroRNA Detection Methodologies

MicroRNAs (miRNAs or miRs) are small noncoding RNAs involved in the fine regulation of post-transcriptional processes in the cell. The physiological levels of these short (20-22-mer) oligonucleotides are important for the homeostasis of the organism, and therefore dysregulation can lead to the onset of cancer and other pathologies. Their importance as biomarkers is constantly growing and, in this context, detection methods based on the hybridization to peptide nucleic acids (PNAs) are gaining their place in the spotlight. After a brief overview of their biogenesis, this review will discuss the significance of targeting miR, providing a wide range of PNA-based approaches to detect them at biologically significant concentrations, based on electrochemical, fluorescence and colorimetric assays.

Nanofiber-integrated miniaturized systems: an intelligent platform for cancer diagnosis

Cancer diagnostic tools enabling screening, diagnosis, and effective disease management are essential elements to increase the survival rate of diagnosed patients. Low abundance of cancer markers present in large amounts of interferences remains the major issue. Moreover, current diagnostic technologies are restricted to high-resourced settings only. Integrating nanofibers into miniaturized analytical systems holds a significant promise to address these challenges as demonstrated by recent publications. A large surface area, three-dimensional porous network, and diverse range of functional chemistries make nanofibers an excellent candidate as immobilization support and/or transduction elements, enabling high capture yield and ultrasensitive detection in miniaturized devices. Functional nanofibers have thus been used to isolate and detect various cancer-related biomarkers with a high degree of success in both on-chip and off-chip platforms. In fact, the chemical and functional adaptability of nanofibers has been exploited to address the technical challenges unique to each of the cancer markers in body fluids, where circulating tumor cells are prominently investigated among others (proteins, nucleic acids, and exosomes). So far, none of the work has exploited the nanofibers for cancer-derived exosomes, opening an avenue for further research effort. The trend and future prospects signal possibilities to strengthen the implementation of nanofiber-miniaturized system hybrid for a next generation of cancer diagnostic platforms both in clinical and point-of-care testing.

Target-assisted FRET signal amplification for ultrasensitive detection of microRNA

The recycling of target miRNA and high quenching efficiency of nanogold greatly improved the sensitivity for miRNA detection.

Ultrasensitive detection of nucleic acids based on dually enhanced fluorescence polarization

Increase of the molecular volume and quenching effect induced by AuNP conjugation can both enhance the fluorescence polarization of Alexa488.

Peptide Nucleic Acid-Based Biosensors for Cancer Diagnosis

The monitoring of DNA and RNA biomarkers freely circulating in the blood constitutes the basis of innovative cancer detection methods based on liquid biopsy. Such methods are expected to provide new opportunities for a better understanding of cancer disease at the molecular level, thus contributing to improved patient outcomes. Advanced biosensors can advance possibilities for cancer-related nucleic acid biomarkers detection. In this context, peptide nucleic acids (PNAs) play an important role in the fabrication of highly sensitive biosensors. This review provides an overview of recently described PNA-based biosensors for cancer biomarker detection. One of the most striking features of the described detection approaches is represented by the possibility to detect target nucleic acids at the ultra-low concentration with the capability to identify single-base mutations.

Signal enhancement in ligand–receptor interactions using dynamic polymers at quartz crystal microbalance sensors

The signal enhancement properties of QCM sensors based on dynamic, biotinylated poly(acrylic acid) brushes has been studied in interaction studies with an anti-biotin F_ab fragment.