Cell-free DNA (cfDNA) refers to short fragments of acellular nucleic acids detectable in almost all body fluids, including blood, and is involved in various physiological and pathological phenomena such as immunity, coagulation, aging, and cancer. In cancer patients, a fraction of hematogenous cfDNA originates from tumors, termed circulating tumor DNA (ctDNA), and may carry the same mutations and genetic alterations as those of a primary tumor. Thus, ctDNA potentially provides an opportunity for noninvasive assessment of cancer. Recent advances in ctDNA analysis methods will potentially lead to the development of a liquid biopsy tool for the diagnosis, prognosis, therapy response monitoring, and tracking the rise of new mutant sub-clones in cancer patients. Over the past few decades, cancer-specific mutations in ctDNA have been detected using a variety of untargeted methods such as digital karyotyping, personalized analysis of rearranged ends (PARE), whole-genome sequencing of ctDNA, and targeted approaches such as conventional and digital PCR-based methods and deep sequencing-based technologies. More recently, several chip-based electrochemical sensors have been developed for the analysis of ctDNA in patient samples. This paper aims to comprehensively review the diagnostic, prognostic, and predictive potential of ctDNA as a minimally invasive liquid biopsy for cancer patients. We also present an overview of current advances in the analytical sensitivity and accuracy of ctDNA analysis methods as well as biological and technical challenges, which need to be resolved for the integration of ctDNA analysis into routine clinical practice.

Rapid, sensitive, and selective bacterial detection is a hot topic, because the progress in this research area has had a broad range of applications. Novel and innovative strategies for detection and identification of bacterial nucleic acids are important for practical applications. Microfluidics is an emerging technology that only requires small amounts of liquid samples. Microfluidic devices allow for rapid advances in microbiology, enabling access to methods of amplifying nucleic acid molecules and overcoming difficulties faced by conventional. In this review, we summarize the recent progress in microfluidics-based polymerase chain reaction devices for the detection of nucleic acid biomarkers. The paper also discusses the recent development of isothermal nucleic acid amplification and droplet-based microfluidics devices. We discuss recent microfluidic techniques for sample preparation prior to the amplification process.

Liquid marbles can serve as a biochemical reactor for the polymerase chain reaction, eliminating the conventional single use plastic reaction vial.

Over the last three decades, the protocols and procedures of the DNA amplification technique, polymerase chain reaction (PCR), have been optimized and well developed. However, there have been no significant innovations in processes for sample dispersion for PCR that have reduced the amount of single-use or unrecyclable plastic waste produced. To address the issue of plastic waste, this paper reports the synthesis and successful use of a core-shell bead microreactor using photopolymerization of a composite liquid marble as a dispersion process. This platform uses the core-shell bead as a simple and effective sample dispersion medium that significantly reduces plastic waste generated compared to conventional PCR processes. Other improvements over conventional PCR processes of the novel dispersion platform include increasing the throughput capability, enhancing the performance and portability of the thermal cycler, and allowing for the contamination-free storage of samples after thermal cycling.

We report the electrocatalytic activity of a new class of superparamagnetic nanoparticles, graphene‐oxide‐loaded iron oxide (GO/IO hybrid material), towards the reduction of ruthenium hexaammine(III) chloride (Ru(NH3)6]3+, RuHex). Leveraging the electrocatalytic activity of the GO/IO hybrid material and the signal enhancement capacity of [Ru(NH3)6]3+/[Fe(CN)6]3− in an electrocatalytic cycle, an ultrasensitive and specific electrochemical sensor was developed for the detection of cancer‐related microRNA (miRNA). Using the direct affinity interaction between RNA and graphene oxide, magnetically isolated and purified target miRNA were directly adsorbed onto a screen‐printed electrode modified with the GO/IO hybrid material. The detection was enabled by chronocoulometric (CC) readout of charge‐compensating [Ru(NH3)6]3+ followed by an enhancement in CC charge display through the Ru(NH3)6]3+/[Fe(CN)6]3− system. We demonstrate an excellent limit of detection of 1.0 fM by accurately detecting miR‐21 in synthetic samples and showcase its clinical utility in ovarian cancer cell lines with high sensitivity (ten cells) and good reproducibility (% RSD=<5 %, for n=3).