Bioelectrochemistry of nucleic acids for early cancer diagnostics – analysis of DNA methylation and detection of microRNAs

Dysregulation of gene expression mechanisms has been observed in many tumors, making their analysis of utmost importance. These mechanisms include DNA methylation, an epigenetic mechanism in which 5-carbon of cytosine becomes methylated, leading to gene silencing, and action of short RNA molecules called microRNAs, which regulate protein synthesis at post-transcriptional level by binding to mRNAs. In this review, we describe major roles of both mechanisms in carcinogenesis, offer an overview of currently used methods for their analysis, and summarize most recent advances in electrochemical-based assays and strategies. Advantages of electrochemistry, including favorable cost, time of experiment, or simple instrumentation, are highlighted, along with current challenges that need to be addressed prior to successful application into clinical routine.

A terahertz-vibration to terahertz-radiation converter based on gold nanoobjects: a feasibility study

Background: The need for practical and adaptable terahertz sources is apparent in the areas of application such as early cancer diagnostics, nondestructive inspection of pharmaceutical tablets, visualization of concealed objects. We outline the operation principle and suggest the design of a simple appliance for generating terahertz radiation by a system of nanoobjects – gold nanobars (GNBs) or nanorings (GNRs) – irradiated by microwaves. Results: Our estimations confirm a feasibility of the idea that GNBs and GNRs irradiated by microwaves could become terahertz emitters with photon energies within the full width at half maximum of the longitudinal acoustic phononic DOS of gold (ca. 16–19 meV, i.e., 3.9–4.6 THz). A scheme of the terahertz radiation source is suggested based on the domestic microwave oven irradiating a substrate with multiple deposited GNBs or GNRs. Conclusion: The size of a nanoobject for optimal conversion is estimated to be approx. 3 nm (thickness) by approx. 100 nm (length of GNB, or along the GNR). This detailed prediction is open to experimental verification. An impact is expected onto further studies of interplay between atomic vibrations and electromagnetic waves in nanoobjects.