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Early detection of cancers and their precise subtyping are essential to patient stratification and effective cancer management. Data-driven identification of expression biomarkers coupled with microfluidics-based detection shows promise to revolutionize cancer diagnosis and prognosis. MicroRNAs play key roles in cancers and afford detection in tissue and liquid biopsies. In this review, we focus on the microfluidics-based detection of miRNA biomarkers in AI-based models for early-stage cancer subtyping and prognosis. We describe various subclasses of miRNA biomarkers that could be useful in machine-based predictive modeling of cancer staging and progression. Strategies for optimizing the feature space of miRNA biomarkers are necessary to obtain a robust signature panel. This is followed by a discussion of the issues in model construction and validation towards producing Software-as-Medical-Devices (SaMDs). Microfluidic devices could facilitate the multiplexed detection of miRNA biomarker panels, and an overview of the different strategies for designing such microfluidic systems is presented here, with an outline of the detection principles used and the corresponding performance measures. Microfluidics-based profiling of miRNAs coupled with SaMD represent high-performance point-of-care solutions that would aid clinical decision-making and pave the way for accessible precision personalized medicine. [ABSTRACT FROM AUTHOR]

Miniaturization of electrochemical components has become less common in the last decade, with the focus predominantly being the design and development of state-of-the-art microelectrodes for achieving small volume analysis of samples. However, such microelectrodes involve cumbersome processing procedures to convert the base material for the required application. A potential paradigm shift in such miniaturization could be achieved by using cheaper alternatives such as plastics to build electrochemical components, such as micropipette tips made of polypropylene, which are commercially available at ease. Hence, this work presents the design of an electrochemical working electrode based upon a micropipette tip, involving minimal processing procedures. Furthermore, such a working electrode was realized by sputtering silver onto a bare micropipette tip using a radio-frequency sputtering technique, to obtain electrical contacts on the tip, followed by hydrothermal growth of ZnO, which acted as the active electrode material. The ZnO nanostructures grown on the micropipette tip were characterized for their morphology and surface properties using a scanning electron microscope (SEM), laser microscope, Raman spectrometer, and X-ray photoelectron spectrometer (XPS). The developed micropipette tip-based electrode was then used as the working electrode in a three-electrode system, wherein its electrochemical stability and properties were analyzed using cyclic voltammetry (CV). Furthermore, the above system was used to detect glucose concentrations of 10–200 µM, to evaluate its sensing properties using amperometry. The developed working electrode exhibited a sensitivity of 69.02 µA/µM cm−2 and limit of detection of 67.5 µM, indicating the potential for using such modified micropipette tips as low-cost miniaturized sensors to detect various bio-analytes in sample solutions. [ABSTRACT FROM AUTHOR]

Formalin has been used as the preservative of fishes in the concentration range of 15–25 mgL−1. However, there have been a high frequency of violations in the optimum use of formalin levels. The consumption of fishes treated with excessive formalin levels leads to nasopharynx, leukaemia and sinonasal cancer and there is a huge demand for the development of formalin sensor. Conventional formalin sensors such as chromogenic and mass balance sensors fall short in real-time analysis due to the lack of specificity and sensitivity in the interference medium. In this context, it has been emphasized to develop a non-enzymatic electrochemical biosensor with microwave synthesized CdS nanoparticles as a nanointerface owing to its surface limited kinetics. NaCl of 1 mM was considered as an electrolyte solution in the present study. Dynamic sensing characteristics with varying formalin levels of 5–50 mgL−1 was studied in three different concentration ranges as 5–15 mgL−1 (concentration of formalin < NaCl; conversion of formalin to formic acid), 20–30 mgL−1 (concentration of formalin ∼ NaCl; equilibrium between the oxidative and reductive product), 35–50 mgL−1 (concentration of formalin > NaCl; complete oxidation of formic acid to CO 2). Hence, with the exhibition of such a dynamic sensitivity based on electrolyte, the developed biosensor acts as an electrochemical comparator showcasing a switch-like behaviour in detecting formalin levels. The threshold concentration of formalin required for the comparator effect was found to be 14.845 mgL−1. The developed biosensor, most essentially, exhibited a versatility in quantifying formalin levels in real-time fish samples. Image 1 • Electrochemical detection of formalin using CdS nanoparticles as nanointerface. • Dynamic sensitivity based on electrolyte concentration showcasing a switch-like behaviour. • A novel electrochemical comparator effect is reported. • Heterogeneous rate constant and surface coverage are consistent with comparator effect. • Threshold concentration of formalin to exhibit comparator effect is 14.845 mgL−1. [ABSTRACT FROM AUTHOR]