Microfluidics and Nanofluidics最新文献

In this study, we propose and develop an autonomous picoliter droplet array-generating device using a centrifugal microfluidic system. Droplet arrays play a crucial role in the advancement of chemical analyses, such as digital quantification and digital PCR. In digital quantification, it is important to standardize the size of the droplets and ensure the ease of analysis of the detection reactions within each droplet. Hence, we developed a device that can form droplets of a predetermined size within pre-arranged cup structures simply by flowing liquid and successfully controlled the flow for generating picoliter droplet arrays. The flow control was conducted simply by rotation, and it was not necessary to customize the centrifuge. By optimizing the cup arrangement and these spaces, the device realized that approximately140 pL of highly uniform droplets with an area concentration as high as 32 pieces per square millimeter. Moreover, by implementing an evaporation-prevention function, it was confirmed that the droplets could be retained for more than 30 min. Owing to its simplicity, it is expected to make a significant contribution to the widespread adoption of digital quantification and advancement of analysis.

The present investigation considers roughness elements which are generally very small relative to the principal flow length scale, and about the same order of magnitude as the molecular mean free path of helium. Significantly different rarefaction flow behavior is produced using three roughness arrangements, which have different character and structure in regard to distributions of larger ridges, as well as sizes, shapes, and distributions of smaller roughness elements. Measured distributions of slip velocity and associated tangential momentum accommodation coefficients are provided as they vary with Knudsen number Kn, disk rotation speed ω, and mean roughness height Ra. Results are given for helium and air as working fluids, three different surface roughness types, different disk rotational speeds ω, different volumetric flow rates, and different flow passage heights h. Knudsen number values range from 5.21 × 10^–3 to 2.15 × 10^–2 for helium, and from 1.82 × 10^–3 to 7.53 × 10^–3 for air. The device employed to produce these data is a viscous disk pump (VDP). With smallest mean roughness height, all of the elements on the surface are about the same size, which is about the same as the molecular mean free path of helium, and a larger percentage of molecules are subject to specular reflection resulting in substantial slip velocity magnitudes. With largest mean roughness height, a diversity of roughness element sizes, shapes, and heights is present, and a larger percentage of molecules are subject to diffuse reflection resulting in relatively small slip velocity magnitudes.

Microfluidic devices have emerged as transformative tools in the field of targeted drug delivery, offering unprecedented precision, efficiency, and control. Patented innovations in microfluidics focus on creating tailored delivery systems capable of overcoming biological barriers, optimizing therapeutic dosing, and minimizing systemic side effects. By integrating advanced materials, microfabrication techniques, and dynamic fluid control, these devices enable localized and sustained release of therapeutics. Applications span oncology, neurology, and chronic disease management, addressing challenges such as drug stability, biodistribution, and cellular targeting. This paper explores patented microfluidic technologies, emphasizing their design principles, functional mechanisms, and their role in revolutionizing drug delivery. Furthermore, we discuss the future prospects and commercialization potential of these devices as key enablers of personalized medicine.

Colorimetric microfluidic paper-based analytical devices (µPADs) offer a promising platform for point-of-care diagnostics due to their simplicity, portability, and low cost. However, their limited dynamic range, typically restricted by a single reagent concentration, often necessitates sample dilution, increasing analysis time and complexity. This work presents a novel strategy to expand the dynamic range of µPADs by integrating varying reagent concentrations within a single device. This approach was demonstrated for the detection of cysteine (Cys), a biomolecule with a wide concentration range in biological and food samples. Indirect Cys quantification was performed by reacting it with Ag(I) prior to the determination of the remaining Ag(I) using K₂CrO₄. Despite the inherent interference from halides in this assay, an integrated online halide removal layer was incorporated into the sensor. Moreover, the interference from other amino acids was not found, indicating high selectivity. A wide linear range of six orders of magnitude (0.0001-10 mg mL^− 1) with a limit of detection of 0.03 µg mL^− 1 was achieved using the multi-concentration approach. The developed µPADs were successfully applied to the analysis of Cys in food samples, achieving high accuracy with recoveries ranging from 87.0 to 107.8%. This innovative approach holds significant potential for enhancing the analytical capabilities of µPADs for various point-of-care applications.

The opportunistic fungus Candida albicans has become the major cause of hospital-acquired infections due to its ability to develop biofilms that resistance to treatments. his study monitored the real-time growth and inhibition of C. albicans hyphal and biofilm formation using optoelectrochemical approaches, focusing on Secreted Aspartyl Protease 5 (SAP5), a key virulence factor. The natural phenolic compound 4-Hydroxyphenylacetic acid (4-HPA) was computationally screened and demonstrated strong binding affinity to SAP5. In vitro studies indicated a minimum biofilm inhibitory concentration (MBIC) of 4 mg/mL and a minimum biofilm eradication concentration (MBEC) of 16 mg/mL. The 4-HPA exhibited considerable potential as an anti-hyphal and anti-biofilm agent, achieving efficacy > 90% in the Biofilm Infection Simulator System (BISS) platform. Likewise, in microfluidic platform, electrochemical analysis revealed 85–90% biofilm inhibition & reduction on MBIC & MBEC doses, respectively. The correlation of microscopic images with electrochemical data revealed complementarity, introducing a novel approach for monitoring microbial biofilms. This study introduces a novel approach to monitoring and treating biofilms, offering promising insights for anti-biofilm drug development.

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The biocompatibility of materials and processes used in the fabrication of three-dimensional (3D) culture devices is crucial for the success of some relevant studies. In this context, 3D printing emerges as a promising technology to be used. This study evaluated three resins as candidates for the production of 3D culture devices: PriZma 3D Bio Splint (resin 1), 3D Prime Premium Cristal (resin 2), and Quanton Spin Skin Opaca (resin 3). Cubic samples of 2 mm and 3 mm were fabricated using a DLP 3D printer, followed by post-processing and sterilization. Biocompatibility was assessed using immortalized BSC-40 cells cultured in 96-well plates using MTT colorimetric assay to estimate cellular viability. A material is considered biocompatible if cell viability is above 70%. Resins 1 and 3 demonstrated high biocompatibility, with cell viability exceeding 80% and no significant differences between sample sizes. In contrast, the cell viability of resin 2 ranged from 60 to 66%. Based on these results, simplified devices for 3D cultures were produced with resin 1, due to its characteristics, particularly its transparency, which facilitates culture protocols and microscopic observations. After 4 days of culture, cells exhibited a three-dimensional morphology with long cellular projections and high viability when evaluated by fluorescence microscopy. We conclude that resins 1 is suitable for device fabrication, while resin 2 and 3 are not recommended because of the low biocompatibility and the opacity. respectively. The chosen materials show great potential for the production of devices for short term 3D cell cultures, an expanding and highly relevant area of scientific research.

The accurate and rapid detection of H1N1 viral specific protein is crucial for effective disease control and management. Traditional diagnostic methods based on ELISA immunoassay often require complex manual operations, long incubation times, and lack the integration needed for automated, high-throughput analysis. There is an urgent demand for a portable, sensitive, integrated, and fully automated diagnostic platform to address these challenges in medical diagnostics. We developed an automated diagnostic system that integrates nanozyme-based detection within a centrifugal microfluidic device for rapid H1N1 viral specific protein detection. The system utilizes nanozymes for signal amplification, leveraging nanozymes to reduce assay times. A high-resolution image sensor and image processing algorithm enable precise interrogation of test results, demonstrating significant improvements in sensitivity. The compact centrifugal microfluidic device automates the sequential delivery of samples, reagents, and nanozyme probes, seamlessly implements mixing, incubation, and liquid transfer. The system achieves a 50-fold sensitivity improvement over the conventional method based on colloidal gold lateral flow strips, with a test time of only 15 min. This work develops a fully automated, integrated diagnostic platform by combining nanozyme-enhanced immunoassay with automatic centrifugal microfluidics. The platform eliminates manual intervention, achieving high sensitivity and rapid detection of infectious disease viral specific protein. Its compact and integrated design makes it a versatile tool for point-of-care diagnostics.

A dripping-regime segmented-flow microfluidic reactor for the continuous production of gold nanoparticles (Au NPs) was designed based on computational fluid dynamics calculations. A flow-focusing junction was applied. Diethyl carbonate (DEC) was used as a green material for the continuous phase. The dispersed aqueous phase consisted of HAuCl₄, NaBH₄, and PVA. Experimental dispersed phase droplet diameter as a function of Capillary number (Ca) corroborated with the CFD calculations. The effect of Ca (0.0013,0.0025 and 0.0050) and pH (1,3 and 11) on HAuCl₄ conversion and Au NPs particle size distribution (PSD) was investigated. Based on nanoparticle tracking analysis (NTA), average particle diameters as small as 1.73 nm with a sharp distribution (standard deviation of 0.27 nm) could be achieved. The apparent pseudo-first-order reduction reaction rate constant was found proportional to the average vorticity within the droplets. Particle growth was not dominated by coalescence processes. No leaching of Au³⁺ by DEC was detected.

In healthcare and industry, infections caused by biofilms and unwanted buildup in the environment are big problems, making it important to have affordable and easy-to-use monitoring tools. The study aims to create an affordable and eco-friendly electrochemical microfluidic device that can easily check biofilm growth without needing invasive methods, making it simpler and cheaper than traditional biosensors. The fabrication of the microfluidic device involved a resource-efficient approach, utilizing 3-D printed molds made from acrylonitrile butadiene styrene material, followed by polydimethylsiloxane casting to form the channels. Screen-printed electrodes (SPEs) were integrated into the device, and acetone washing was used for channel formation. The device performed testing with one bacterial strain (Staphylococcus aureus), one fungal strain (Candida albicans), and two real samples (clinical blood and wastewater) employing impedance methods. Additionally, the study simulated real-world conditions by utilizing clinical and wastewater samples to monitor biofilm growth. Biofilm development in the microfluidic device exhibited a sigmoidal growth pattern, with impedance increases of ~ 74.4% for S. aureus, 73.78% for C. albicans, and 82.7% and 87.34% for clinical and wastewater samples, respectively. High-resolution SEM imaging confirmed the presence of biofilms on the surface of the SPEs. The dynamic range of the device was found to be 1291.57–1811.25 ohms, with a limit of detection of 0.208 CFU/mL and a sensitivity of 10.83 µA/CFU/mL. The device's sustainable fabrication process and reliable performance make it a practical option for researchers with limited resources, offering a valuable alternative to traditional biofilm study methods.

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