Search Results (6)

In large-scale radiological events, there is a need to triage affected individuals based on their biological absorbed dose. Biodosimetry measures biological responses in relation to the received dose. Radiation-responsive protein biomarkers in peripheral blood lymphocytes, especially intracellular proteins, have been validated for biodosimetry with immunochemical-based measurement methods. However, these antibody-based assays can suffer from stability and batch-to-batch variations. Aptamers are single-stranded oligonucleotide alternatives to antibodies that are stable and much smaller in size, making them ideal probes for intracellular targets. However, few aptamers have been developed against intracellular targets, and these efforts are especially hampered due to the time-consuming nature of the conventional aptamer selection method. An efficient method for isolating aptamers against intracellular radiation-responsive proteins is not available yet. Herein, we used a microfluidic aptamer isolation method to develop an aptamer against the intracellular radiation biomarker BAX in blood lymphocytes. The isolated aptamer has a dissociation constant of 6.95 nM against human BAX protein and a bright detail similarity score of 1.9 when colocalizing with anti-BAX aptamer intracellularly. The in situ labeling of the intracellular BAX protein also shows the aptamer can be used to differentiate 2.5 Gy or 3 Gy of radiation in ex vivo human and in vivo mouse peripheral blood samples exposed to X-rays. In conclusion, this proof-of-concept study indicates that the microfluidic-enabled aptamer isolation method could be used for the development of a panel of targeted intracellular proteins for radiation biodosimetry applications. Full article

Exosomes carry diverse tumor-associated molecular information that can reflect real-time tumor progression, making them a promising tool for liquid biopsy. However, traditional methods for exosome isolation and detection often rely on large, expensive equipment and are time-consuming, limiting their practical applicability in clinical settings. Microfluidic technology offers a versatile platform for exosome analysis, with advantages such as seamless integration, portability and reduced sample volumes. Aptamers, which are single-stranded oligonucleotides with high affinity and specificity for target molecules, have been frequently employed in the development of aptamer-based microfluidics for the isolation, signal amplification, and quantitative detection of exosomes. This review summarizes recent advances in aptamer-based microfluidic strategies for exosome analysis, including (1) strategies for on-chip exosome capture mediated by aptamers combined with nanomaterials or nanointerfaces; (2) aptamer-based on-chip signal amplification techniques, such as enzyme-free hybridization chain reaction (HCR), rolling circle amplification (RCA), and DNA machine-assisted amplification; and (3) various aptamer-assisted detection methods, such as fluorescence, electrochemistry, surface-enhanced Raman scattering (SERS), and magnetism. The limitations and advantages of these methods are also summarized. Finally, future challenges and directions for the clinical analysis of exosomes based on aptamer-based microfluidics are discussed. Full article

Rapid detection of okadaic acid (OA) in shellfish is crucial for practical application in food safety analysis. In order to establish a rapid, delicate detection scheme, an OA aptamer was utilized to quickly capture OA from the sample solution with polystyrene microspheres as solid phase carriers, and an inner-microchannel dam structure was designed to intercept the aptamer-functionalized microspheres to achieve the separation of OA for detection. Horseradish peroxidase (HRP) is utilized to catalyze the luminescence reaction of luminol-H₂O₂ solution. Through the direct competition for the aptamer between OA and OA-HRP, the rapid detection of OA can be achieved. The dynamic range of this detection method is 41.3–4.02 ng/mL, and the limit of detection (LOD) and lowest limit of quantitation (LOQ) are 12.4 pg/mL and 41.3 pg/mL, respectively. This miniaturized device enables rapid, ultrasensitive detection of OA, and demonstrates the merits of its field portability and low reagent consumption. The device can be deployed for on-site detection and analysis of marine biotoxins thereof. Full article

Exosomes (30–100 nm in diameter) are a group of cell-derived membrane vesicles, packaged as valuable cargo with lipid, proteins, and genetic materials from their parent cells. With the increasing interest in exosomes for diagnostic and therapeutic applications, the rapid isolation of pure exosome populations has become a hot topic. In this paper, we propose modified microchannels with aptamer in a microfluidics system for rapid and efficient isolation of exosomes by targeting exosome-carrying CD63 and PTK 7. The capture efficiency in surface-modified channels reaches around 10⁷–10⁸ particles/mL in 20 min, and purified exosomes with reliable size can be achieved. Full article

In this paper, we developed an isolation system for A549 human lung carcinoma cells as an effective factor for the early diagnosis of lung cancer. A microfluidic immunomagnetic method was used, in which the combination of immunomagnetic separation and a microfluidic system allowed for increased isolation efficiency with uncomplicated manipulation. In the microfluidic immunomagnetic strategy, A549 cells were combined with aptamer-conjugated carboxylated magnetic beads and then collected in a specified region by applying a magnetic field. The results were recorded using a fluorescence microscope, and the captured targets were then quantified. The isolation efficiency of A549 cells is up to 77.8%. This paper developed a simple working procedure, which is less time consuming, high-throughput, and trustworthy for the isolation of A549 cells. This procedure can be a useful reference method for the development of an effective diagnosis and treatment method for lung cancer in the future. Full article

Aptamers are single-stranded oligonucleotides of DNA or RNA that bind to target molecules with high affinity and specificity. Typically, aptamers are generated by an iterative selection process, called systematic evolution of ligands by exponential enrichment (SELEX). Recent advancements in SELEX technology have extended aptamer selection from comparatively simple mixtures of purified proteins to whole living cells, and now cell-based SELEX (or cell-SELEX) can isolate aptamers that bind to specific target cells. Combined with nanotechnology, microchips, microfluidic devices, RNAi and other advanced technologies, cell-SELEX represents an integrated platform providing ultrasensitive and highly specific tools for clinical medicine. In this review, we describe the recent progress made in the application of cell-SELEX for diagnosis, therapy and biomarker discovery. Full article