Detection of miRNA in cell cultures by using microchip electrophoresis with a fluorescence-labeled riboprobe

Improving tumor microenvironment assessment in chip systems through next-generation technology integration

The tumor microenvironment (TME) comprises a diverse array of cells, both cancerous and non-cancerous, including stromal cells and immune cells. Complex interactions among these cells play a central role in driving cancer progression, impacting critical aspects such as tumor initiation, growth, invasion, response to therapy, and the development of drug resistance. While targeting the TME has emerged as a promising therapeutic strategy, there is a critical need for innovative approaches that accurately replicate its complex cellular and non-cellular interactions; the goal being to develop targeted, personalized therapies that can effectively elicit anti-cancer responses in patients. Microfluidic systems present notable advantages over conventional in vitro 2D co-culture models and in vivo animal models, as they more accurately mimic crucial features of the TME and enable precise, controlled examination of the dynamic interactions among multiple human cell types at any time point. Combining these models with next-generation technologies, such as bioprinting, single cell sequencing and real-time biosensing, is a crucial next step in the advancement of microfluidic models. This review aims to emphasize the importance of this integrated approach to further our understanding of the TME by showcasing current microfluidic model systems that integrate next-generation technologies to dissect cellular intra-tumoral interactions across different tumor types. Carefully unraveling the complexity of the TME by leveraging next generation technologies will be pivotal for developing targeted therapies that can effectively enhance robust anti-tumoral responses in patients and address the limitations of current treatment modalities.

Multiplexed miRNA Quantitation Using Injectionless Microfluidic Thermal Gel Electrophoresis

MicroRNAs (miRNAs) are a class of biomolecules that have high clinical and pharmaceutical significance because of their ability to regulate protein expression. Better methods are needed to quantify target miRNAs, but their similar sequence lengths and low concentrations in biomedical samples impede analysis. This report aimed to develop a simple, rapid method to directly quantify multiple miRNAs using microfluidic thermal gel electrophoresis (TGE). Fluorescent probes were designed complementarily in sequence to four target miRNAs that also contained variable DNA overhangs to alter their electrophoretic mobilities. Samples and probes were directly added into thermal gel and loaded throughout a microchannel. Applying voltage resulted in an inline preconcentration and separation of the miRNAs that did not require a sample injection nor user intervention to switch between modes. Baseline resolution was achieved between four double-stranded miRNA-probe hybrids and four excess single-stranded probes. Analytical performance was then improved by designing an innovative microfluidic device with a tapered channel geometry. This device exhibited superior detection limits and separation resolution compared to standard channel devices without increasing the complexity of microfabrication or device operation. A proof-of-concept demonstration was then performed, showing that target miRNAs could be detected from cell extracts. These results demonstrate that TGE provides a simple, inexpensive means of conducting multiplexed miRNA measurements, with the potential for automation to facilitate future clinical and pharmaceutical analyses.

The Application of Nucleic Acid Probe-Based Fluorescent Sensing and Imaging in Cancer Diagnosis and Therapy

It is well known that cancer incidence and death rates have been growing, but the development of cancer theranostics and therapeutics has been a challenging work. Recently, nucleic acid probe-based fluorescent sensing and imaging have achieved remarkable improvements in a variety of cancer management techniques, credited to their high sensitivity, good tolerance to interference, fast detection, and high versatility. Herein, nucleic acid probe-based fluorescent sensing and imaging are labeled with advanced fluorophores, which are essential for fast and sensitive detection of aberrant nucleic acids and other cancer-relevant molecules, consequently performing cancer early diagnosis and targeted treatment. In this review, we introduce the characteristics of nucleic acid probes, summarize the development of nucleic acid probe-based fluorescent sensing and imaging, and prominently elaborate their applications in cancer diagnosis and treatment. In discussion, some challenges and perspectives are elaborated in the field of nucleic acid probe-based fluorescent sensing and imaging.

Multiplex MicroRNA Detection on a Surface-Functionalized Power-Free Microfluidic Chip

Circulating microRNAs (miRNAs) have emerged as promising cancer biomarkers because their concentration profiles in body fluids are associated with the type and clinical stage of cancer. For multiplex miRNA detection, a novel surface-functionalized power-free microfluidic chip (SF-PF microchip) has been developed. The inner surface of the SF-PF microchip microchannels was functionalized via electron beam-induced graft polymerization and immobilization of capture probe DNAs. Simultaneous and specific duplex miRNA detection was achieved on the line-type SF-PF microchip with detection limits of 19.1 and 47.6 nmol L^-1 for hsa-miR-16 and hsa-miR-500a-3p, respectively. Moreover, simultaneous and specific triplex miRNA detection was achieved on the stripe-type SF-PF microchip. The sample volume required for this microchip was 0.5 μL, and the time required for detection was 17 min. These results indicate that up to six types of miRNAs could be detected without compromising the advantages of the previous SF-PF microchips for cancer point-of-care testing.

Capillary electrophoresis methods for microRNAs assays: a review

MicroRNAs (miRNAs) are short noncoding RNAs that conduct important roles in many cellular processes such as development, proliferation, differentiation, and apoptosis. In particular, circulating miRNAs have been proposed as biomarkers for cancer, diabetes, cardiovascular disease, and other illnesses. Therefore, determination of miRNA expression levels in various biofluids is important for the investigation of biological processes in health and disease and for discovering their potential as new biomarkers and drug targets. Capillary electrophoresis (CE) is emerging as a useful analytical tool for analyzing miRNA because of its simple sample preparation steps and efficient resolution of a diverse size range of compounds. In particular, CE with laser-induced fluorescence detection is a promising and relatively rapidly developing tool with the potential to provide high sensitivity and specificity in the analysis of miRNAs. This paper covers a short overview of the recent developments and applications of CE systems in miRNA studies in biological and biomedical areas.