Microfluidic Method Research Articles

Microfluidics-mediated Liposomal Nanoparticles for Cancer Therapy: Recent Developments on Advanced Devices and Technologies.

Liposomes, spherical particles with phospholipid double layers, have been extensively studied over the years as a means of drug administration. Conventional manufacturing techniques like thin-film hydration and extrusion have limitations in controlling liposome size and distribution. Microfluidics enables superior tuning of parameters during the self-assembly of liposomes, producing uniform populations. This review summarizes microfluidic methods for engineering liposomes, including hydrodynamic flow focusing, jetting, micro mixing, and double emulsions. The precise control over size and lamellarity afforded by microfluidics has advantages for cancer therapy. Liposomes created through microfluidics and designed to encapsulate chemotherapy drugs have exhibited several advantageous properties in cancer treatment. They showcase enhanced permeability and retention effects, allowing them to accumulate specifically in tumor tissues passively. This passive targeting of tumors results in improved drug delivery and efficacy while reducing systemic toxicity. Promising results have been observed in pancreatic, lung, breast, and ovarian cancer models, making them a potential breakthrough in cancer therapy. Surface-modified liposomes, like antibodies or carbohydrates, also achieve active targeting. Overall, microfluidic fabrication improves reproducibility and scalability compared to traditional methods while maintaining drug loading and biological efficacy. Microfluidics-engineered liposomal formulations hold significant potential to overcome challenges in nanomedicine-based cancer treatment.

Rapid screening of positive blood cultures for extended-spectrum β-lactamases and metallo-β-lactamases using a drug susceptibility testing microfluidic method

ObjectivesAn increasing number of drug-resistant bacteria have been identified recently. In particular, drug-resistant bacteria have been linked to unfavorable prognoses in patients with bacteremia, highlighting the need for rapid testing. Our previous studies have focused on the utility of a drug susceptibility testing microfluidic (DSTM) method using microfluidic channels. A system with this DSTM method for screening for β-lactamases can rapidly detect extended-spectrum β-lactamases (ESBLs) and metallo-β-lactamases (MBLs). In this study, we have evaluated the clinical utility of pre-treatment for screening positive blood cultures using the DSTM method. MethodsA total of 178 positive blood cultures and five simulated samples of MBL-producing bacteria were prepared at Kochi University Hospital, Japan. The pretreatment consisted of a two-step centrifugation. The obtained sediments were screened with the DSTM method for the production of β-lactamase based on morphological changes in the bacteria after 3 h of incubation. ResultsThe pretreatment functioned properly for all samples. Of the 25 ESBL samples, 21 were positive for ESBLs. Four false-negative samples, all obtained from the same patient, contained CTX-M-2 enzyme-producing Proteus mirabilis and showed insusceptibility to an ESBL inhibitor. The simulated samples prepared for MBL screening were positive for MBLs. ConclusionsWhen combined with a method for rapidly identifying bacterial species, DSTM may enable patients with bloodstream infections to start receiving appropriate treatment within 4 h after positive blood cultures are screened.

Precise capture of circulating endometrial cells in endometriosis.

Endometriosis (EM) is a complex benign gynecological disease, but it has malignant biological behavior and can invade any part of the body. Clinical manifestations include pelvic pain, dysmenorrhea, infertility, pelvic nodules, and masses. Our previous study successfully detected circulating endometrial cells (CECs) in the peripheral blood of patients with EM. The purpose of this study is to overcome the limitation of cell size in the previous microfluidic chip method, to further accurately capture CECs, understand the characteristics of these cells, and explore the relationship between CECs and the clinical course characteristics of patients with EM. Human peripheral venous blood used to detect CECs and circulating vascular endothelial cells (CVECs) was taken from EM patients ( n = 34) hospitalized in the Peking University People's Hospital. We used the subtraction enrichment and immunostaining fluorescence in situ hybridization (SE-iFISH) method to exclude the interference of red blood cells, white blood cells, and CVECs, so as to accurately capture the CECs in the peripheral blood of patients with EM. Then we clarified the size and ploidy number of chromosome 8 of CECs, and a second grouping of patients was performed based on clinical characteristics to determine the relationship between CECs and clinical course characteristics. The peripheral blood of 34 EM patients and 12 non-EM patients was evaluated by SE-iFISH. Overall, 34 eligible EM patients were enrolled. The results showed that the detection rates of CECs were 58.8% in EM patients and 16.7% in the control group. However, after classification according to clinical characteristics, more CECs could be detected in the peripheral blood of patients with rapidly progressive EM, with a detection rate of 94.4% (17/18). In total, 63.5% (40/63) of these cells were small cells with diameters below 5 μm, and 44.4% (28/63) were aneuploid cells. No significant association was found between the number of CECs and EM stage. The number and characteristics of CECs are related to the clinical course characteristics of patients with EM, such as pain and changes in lesion size, and may be used as biomarkers for personalized treatment and management of EM in the future.

Enhancing solubility of polymer-loaded febuxostat through ultrasound-assisted microfluidic antisolvent nanoprecipitation: Optimization using Box-Behnken design

Febuxostat (FEB) nanoparticles with the use of poloxamer 407 were prepared using ultrasound assisted microfluidic nanoprecipitation method to enhance febuxostat's solubility and bioavailability. The optimization for this purpose was conducted using the Box Behnken design (BBD) approach. Four factors and three level BBD was used to study the interactive and individual effect of ultrasonic frequency (X1), amplitude (X2), Ultrasound assisted microfluidic reactor (USMR) temperature (X3), and micromixer confluence angle (X4) on selected two responses. Particle size (Y1) and encapsulation efficiency (% EE) (Y2) were the desired responses. The formulated FEB nanoparticles were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). The minimum nanoparticle size, 7.156 nm with 0.22 polydispersity index (PDI) was attained for FEB-loaded polymer nano-sized particles. To investigate the drug release rate (% DR), fast-dissolving tablets of raw FEB and optimized FEB formulation were prepared. A 1.25-fold improvement in FEB solubility rate was experimentally achieved compared to raw FEB. No chemical interaction between the drug and polymer was observed using FTIR. Optimized FEB formulation showed a 92.94 % release rate of the drug in 90 min with 91.70 % EE.

Microfluidic Synthesis and Properties of Thermoresponsive Hydrogel Core–Shell Particles

An approach is demonstrated for the generation of swellable core–shell particles in the sub-millimeter range using a one-step microfluidic method. Particles are made of an agarose gel core and a shell consisting of hydrogel based on crosslinked poly-(N-isopropylacrylamide) (PNIPAM). Solidification of the core was achieved by cooling below the sol–gel temperature, while the shell was cured by photoinitiated co-polymerization. The shell of the particles is reversibly thermoresponsive; it contracts upon heating, releasing water, and becomes hydrophobic. The transition temperature as well as the stability of the particles are mainly affected by the shell monomer composition, while they are less affected by the type of the core material. Such composite particles remain swellable after drying.

Label-free separation of peripheral blood mononuclear cells from whole blood by gradient acoustic focusing

Efficient techniques for separating target cells from undiluted blood are necessary for various diagnostic and research applications. This paper presents acoustic focusing in dense media containing iodixanol to purify peripheral blood mononuclear cells (PBMCs) from whole blood in a label-free and flow-through format. If the blood is laminated or mixed with iodixanol solutions while passing through the resonant microchannel, all the components (fluids and cells) rearrange according to their acoustic impedances. Red blood cells (RBCs) have higher effective acoustic impedance than PBMCs. Therefore, they relocate to the pressure node despite the dense medium, while PBMCs stay near the channel walls due to their negative contrast factor relative to their surrounding medium. By modifying the medium and thus tuning the contrast factor of the cells, we enriched PBMCs relative to RBCs by a factor of 3600 to 11,000 and with a separation efficiency of 85%. That level of RBC depletion is higher than most other microfluidic methods and similar to that of density gradient centrifugation. The current acoustophoretic chip runs up to 20 µl/min undiluted whole blood and can be integrated with downstream analysis.

Multi-Functional Nano-Doped Hollow Fiber from Microfluidics for Sensors and Micromotors.

Nano-doped hollow fiber is currently receiving extensive attention due to its multifunctionality and booming development. However, the microfluidic fabrication of nano-doped hollow fiber in a simple, smooth, stable, continuous, well-controlled manner without system blockage remains challenging. In this study, we employ a microfluidic method to fabricate nano-doped hollow fiber, which not only makes the preparation process continuous, controllable, and efficient, but also improves the dispersion uniformity of nanoparticles. Hydrogel hollow fiber doped with carbon nanotubes is fabricated and exhibits superior electrical conductivity (15.8 S m-1), strong flexibility (342.9%), and versatility as wearable sensors for monitoring human motions and collecting physiological electrical signals. Furthermore, we incorporate iron tetroxide nanoparticles into fibers to create magnetic-driven micromotors, which provide trajectory-controlled motion and the ability to move through narrow channels due to their small size. In addition, manganese dioxide nanoparticles are embedded into the fiber walls to create self-propelled micromotors. When placed in a hydrogen peroxide environment, the micromotors can reach a top speed of 615 μm s-1 and navigate hard-to-reach areas. Our nano-doped hollow fiber offers a broad range of applications in wearable electronics and self-propelled machines and creates promising opportunities for sensors and actuators.

Pore scale investigation of chelating agents flooding for enhanced oil recovery

Recently, laboratory tests have shown a positive response to chelating agent brines in sandstone and carbonate reservoirs as a new enhanced oil recovery technique. There is little research on direct and visual evidence of underlying mechanisms behind the chelating agent effects. In this study, a microfluidic method was established using glass micromodel to investigate the micro-mechanisms of displacement under ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) chelating agent at the pore-scale level. Furthermore, for the study of fluid/fluid interactions, EDTA brine and DTPA brine were brought into contact with two different crude oils to examine the possible compositional changes. For this purpose, sample tests, Fourier Transform Infrared Spectroscopy (FTIR), microscopic image analysis, and dynamic interfacial tension (IFT) measurements were conducted. The FTIR data showed EDTA brine and DTPA brine induced changes in the oil sample composition compared to seawater, which can be related to the formation of water-in-oil micro-dispersions. Microscopic image analysis on samples confirmed the formation of these micro-dispersions. The visual study by the micromodel demonstrated the micro-dispersion formation in the tertiary injection of EDTA and DTPA brine. Based on the observation made, the pore-scale mechanisms of chelating agent flooding involve the chelating agent brine penetrating the crude oil, resulting in micro-dispersion formation. These micro-dispersions tend to alter wettability to a more water-wet state, facilitate oil detachment from the surface, redistribution of oil saturation, and thus leading to improved oil recovery. The observed IFT reduction aids the penetration of EDTA and DTPA brine into the crude oil to form micro-dispersions.

Assessment of pDNA isoforms using microfluidic electrophoresis.

The recent rise in nucleic acid-based vaccines and therapies has resulted in an increased demand for plasmid DNA (pDNA). As a result, there is added pressure to streamline the manufacturing of these vectors, particularly their design and construction, which is currently considered a bottleneck. A significant challenge in optimizing pDNA production is the lack of high-throughput and rapid analytical methods to support the numerous samples produced during the iterative plasmid construction step and for batch-to-batch purity monitoring. pDNA is generally present as one of three isoforms: supercoiled, linear, or open circular. Depending on the ultimate use, the desired isoform may be supercoiled in the initial stages for cell transfection or linear in the case of mRNA synthesis. Here, we present a high-throughput microfluidic electrophoresis method capable of detecting the three pDNA isoforms and determining the size and concentration of the predominant supercoiled and linear isoforms from 2 to 7kb. The limit of detection of the method is 0.1ng/µL for the supercoiled and linear isoforms and 0.5ng/µL for the open circular isoform, with a maximum loading capacity of 10-15ng/µL. The turnaround time is 1min/sample, and the volume requirement is 10µL, making the method suitable for process optimization and batch-to-batch analysis. The results presented in this study will enhance the understanding of electrophoretic transport in microscale systems dependent on molecular conformations and potentially aid technological advances in diverse areas relevant to microfluidic devices.

A Microchip For Exosome Isolation That Can Be Impregnated With Imatinib Simultaneously: An In Vitro Analysis

Background and Aims — Exosomes, which are tiny double-layered membranes originating from eukaryotic cells, have been recognized as a valuable natural vehicle for delivering substances because of their optimal size, compatibility with living organisms, strong structure, ability to carry a large amount of cargo, and capacity to be modified on their surface. Methods — Various strategies have been employed to isolate exosomes due to the challenges associated with maintaining their high purity. The current investigation utilized a soft lithography technique to fabricate channels for exosome separation, incorporating immunoaffinity capabilities. Both biochemical and biophysical assays were conducted to assess the quality of isolated exosomes from various sources (serum, cell supernatant, and urine) and compared with a commercially available kit. Results — The current investigation employed a microfluidic method to capture CD63-conjugated magnetic beads, resulting in a very effective separation of exosomes. Based on the data, there were no notable variations in miRNAs that were statistically significant. This demonstrates that the engineered chip successfully achieved the separation of the exosome while preserving the integrity of its nucleic acid components. Conclusion — The results shown that the current methodology effectively isolated exosomes with a high yield rate, purity, and minimal time requirement. The imatinib laden exosomes demonstrated anticancer efficacy against the KYO-1 cell line in all of their forms.

Abstract 7173: Animal pharmacokinetics of an anti-Her2+ immunoliposome of docetaxel

Abstract Despite the success of docetaxel in combination with trastuzumab in HER2+ breast cancer, docetaxel still has serious limitations, including poor water solubility and the canonical systemic toxicity of taxanes. These side effects of taxanes need to be overcome to improve patient management. In this context, we have developed a nanoparticle drug delivery system. We have developed an immunoliposome loaded with docetaxel and grafted with trastuzumab using a microfluidic method by mixing an aqueous phase (KH2PO4 buffer) and an organic phase composed of phosphatidylcholine, cholesterol and PEGmal in a molar ratio of 50:31:1, to which docetaxel is added at a rate of 1.8% of the total lipid. We perform a thiolation reaction to graft the trastuzumab onto the polyethylene glycol chain. Resulting immunoliposomes were characterized by a mean diameter of 140 nm, a docetaxel encapsulation rate of 73% and a trastuzumab uptake rate of 400 units of trastuzumab by nanoparticle. C57BL/6 mice were administered with docetaxel 1.9 mg/kg and trastuzumab 160 ng/kg or a mixture of free drugs or as liposomes at the same dose by intraperitoneal injection. Blood was collected 1h, 2h, 3h, 6h, 8h and 24h after injection and plasma was analyzed by HPLC-UV with Paclitaxel as internal standard. For each treatment group, pharmacokinetic parameters and exposure metrics were calculated using PKanalix®: half-life T1/2, elimination rate constant Kel and area under the curve AUC at the end points (AUCtlast) and infinity (AUCinfinity). Statistical tests were performed with Sigmastats®. The results showed a marked change in pharmacokinetics with increased plasma exposure with liposomal docetaxel. Preliminary results show a longer half-life for liposomal docetaxel (40.76 h VS. 4.33 h, i.e., a 9.4-fold increase). The concentration of docetaxel appeared to decrease more rapidly between T1h and T6h with free docetaxel (Kel 0.16h-1) than with liposomal docetaxel (Kel 0.017h-1). The concentration of docetaxel reached a plateau over time, up to 24 hours (52.72± 9.45 ng/ml) in mice treated with immunoliposomes whereas Docetaxel was undetectable at T24h when treated with free drugs. There was a statistical difference in PK at T6h between liposomal docetaxel and free docetaxel, 69.86 ± 15.25 ng/ml and 53.67 ± 4.92 ng/ml, respectively (p < 0.001, non-paired t-test). Liposomal docetaxel showed higher AUC0-t (x3.75) and AUC0-∞ values (x5.9) compared to non-liposomal docetaxel. In conclusion, these preliminary results suggest that we have developed a promising immunoliposome for the systemic delivery of docetaxel in HER2+ breast cancer with sustained exposure. Citation Format: Mathilde Dacos, Erwan Diroff, Sarah Giacometti, Joseph Ciccolini, Raphaelle Fanciullino. Animal pharmacokinetics of an anti-Her2+ immunoliposome of docetaxel [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7173.

Chemotactic Interactions of Scenedesmus sp. and Azospirillum brasilense Investigated by Microfluidic Methods

The use of algae for industrial, biotechnological, and agricultural purposes is spreading globally. Scenedesmus species can play an essential role in the food industry and agriculture due to their favorable nutrient content and plant-stimulating properties. Previous research and the development of Scenedesmus-based foliar fertilizers raised several questions about the effectiveness of large-scale algal cultivation and the potential effects of algae on associative rhizobacteria. In the microbiological practice applied in agriculture, bacteria from the genus Azospirillum are one of the most studied plant growth-promoting, associative, nitrogen-fixing bacteria. Co-cultivation with Azospirillum species may be a new way of optimizing Scenedesmus culturing, but the functioning of the co-culture system still needs to be fully understood. It is known that Azospirillum brasilense can produce indole-3-acetic acid, which could stimulate algae growth as a plant hormone. However, the effect of microalgae on Azospirillum bacteria is unclear. In this study, we investigated the behavior of Azospirillum brasilense bacteria in the vicinity of Scenedesmus sp. or its supernatant using a microfluidic device consisting of physically separated but chemically coupled microchambers. Following the spatial distribution of bacteria within the device, we detected a positive chemotactic response toward the microalgae culture. To identify the metabolites responsible for this behavior, we tested the chemoeffector potential of citric acid and oxaloacetic acid, which, according to our HPLC analysis, were present in the algae supernatant in 0.074 mg/ml and 0.116 mg/ml concentrations, respectively. We found that oxaloacetic acid acts as a chemoattractant for Azospirillum brasilense.

High-throughput measurement of elastic moduli of microfibers by rope coiling

There are many fields where it is of interest to measure the elastic moduli of tiny fragile fibers, such as filamentous bacteria, actin filaments, DNA, carbon nanotubes, and functional microfibers. The elastic modulus is typically deduced from a sophisticated tensile test under a microscope, but the throughput is low and limited by the time-consuming and skill-intensive sample loading/unloading. Here, we demonstrate a simple microfluidic method enabling the high-throughput measurement of the elastic moduli of microfibers by rope coiling using a localized compression, where sample loading/unloading are not needed between consecutive measurements. The rope coiling phenomenon occurs spontaneously when a microfiber flows from a small channel into a wide channel. The elastic modulus is determined by measuring either the buckling length or the coiling radius. The throughput of this method, currently 3,300 fibers per hour, is a thousand times higher than that of a tensile tester. We demonstrate the feasibility of the method by testing a nonuniform fiber with axially varying elastic modulus. We also demonstrate its capability for in situ inline measurement in a microfluidic production line. We envisage that high-throughput measurements may facilitate potential applications such as screening or sorting by mechanical properties and real-time control during production of microfibers.

Microfluidic device featuring micro-constrained channels for multi-parametric assessment of cellular biomechanics and high-precision mechanical phenotyping of gastric cells

BackgroundCellular biomechanics plays a significant role in the regulation of cellular physiological and pathological processes. In recent years, multiple methods have been developed to evaluate cellular biomechanics, such as atomic force microscopy (AFM), micropipette aspiration, and magnetic tweezers. However, most of these methods only focus on a single parameter and cannot automate the process at a high-efficiency level. A novel microfluidic method is necessary to achieve the simultaneous multi-parametric measurement of cellular biomechanics and high-precision cellular mechanical phenotyping at high throughput. ResultsTo tackle the issue concerning the low-throughput and cellular single-parameter evaluation, we designed and fabricated a microfluidic chip featuring multiple micro-constrained channels structure, providing a simultaneous multi-parametric assessment of cellular biomechanics, including elastic modulus, recovery capability, and deformability. We compared the biomechanical properties of normal human gastric mucosal epithelial cells (GES-1) and human gastric cancer cells (AGS and MKN-45) by the chip. Results demonstrated that the elastic modulus of GES-1, AGS, and MKN-45 cells decreased sequentially, which was the opposite of their invasiveness and metastasis potential, suggesting the inverse correlation between cellular elastic modulus and malignancy. Meanwhile, the recovery capability and deformability of GES-1, AGS, and MKN-45 cells increased sequentially, demonstrating the positive correlation between cellular deformability and malignancy. Furthermore, multiple parameters were used to distinguish gastric cancer cells from normal gastric cells via machine learning. An accuracy of over 94.8% for identifying gastric cancer cells was achieved. SignificanceThis study provides a deep insight into the biophysical mechanism of gastric cancer metastasis at the single-cell level and possesses great potential to function as a valuable tool for single-cell analysis, thereby facilitating high-precision and high-throughput discrimination of cellular phenotypes that are not easily discernible through single-marker analysis.

CTC-Race: Single-Cell Motility Assay of Circulating Tumor Cells from Metastatic Lung Cancer Patients.

Distinctive subpopulations of circulating tumor cells (CTCs) with increased motility are considered to possess enhanced tumor-initiating potential and contribute to metastasis. Single-cell analysis of the migratory CTCs may increase our understanding of the metastatic process, yet most studies are limited by technical challenges associated with the isolation and characterization of these cells due to their extreme scarcity and heterogeneity. We report a microfluidic method based on CTCs' chemotactic motility, termed as CTC-Race assay, that can analyze migrating CTCs from metastatic non-small-cell lung cancer (NSCLC) patients with advanced tumor stages and enable concurrent biophysical and biochemical characterization of them with single-cell resolution. Analyses of motile CTCs in the CTC-Race assay, in synergy with other single cell characterization techniques, could provide insights into cancer metastasis.

Quantum dots (QDs) attached magnetic beads (MBs) for on-chip efficient capture and detection of bacteria in ready-to-eat (RTE) foods

In this study, we established a versatile and simple magnetic-assisted microfluidic method for fast bacterial detection. Quantum dots (QDs) were loaded onto magnetic beads (MBs) to construct performance enhanced on-chip capture of bacteria. Escherichia coli (E. coli), as a model bacterium was studied. CdSe QDs were deposited onto the surface of Fe3O4 MBs through layer-by-layer self-assembly to enhance the loading of antibodies (Abs). MBs functionalized with anti-E. coli antibody molecules in a micropillar-based microfluidic chip were utilized to capture E. coli, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used for characterization of captured bacteria. This method was found capable of specifically isolating E. coli within the range of 1.0 to 1.0 × 109 CFU/mL, having a detection limit (LOD) of 10 CFU/mL. The average similarity score among mass spectra for the bacterial capture obtained in independent experiments is calculated as 0.97 ± 0.01 (n = 3), which shows this work's excellent reproducibility for bacterial capture. Bacterial growth on ready-to-eat (RTE) foods during its time of storage was successfully monitored. The present protocol has promising potential for microbial control and pathogen detection in the food industry.

Rapid diagnosis of acute myocardial infarction through integrated microfluidic chips for detection of characteristic targets

Myoglobin (Myo), creatine kinase-MB (CKMB), and cardiac troponin I (cTnI) are crucial biomarkers for diagnosing acute myocardial infarction (AMI) The accurate and rapid detection of these three targets can greatly improve the prognosis of AMI patients. Herein, this study developed a microfluidic immunofluorescence method that can detect all three targets in 10–15 min. Ultrasonic atomization and spray technology are used to modify the surface of the injection-molded microfluidic chip (MFC), which effectively solves the problem of biological cross-linking and antibody immobilization on the MFC surface. In addition, it improves the hydrophilicity of the chip surface, thus enhancing fluid self-driving effect. The linear response towards Myo, CKMB and cTnI range from 5 ng/mL to 500 ng/mL, 1 ng/mL to 70 ng/mL, and 0.05 ng/mL to 30 ng/mL, respectively. The intra-batch precision is ≤ 10%, and the inter-batch precision is ≤ 15%. Furthermore, this method shows good consistency compared with the BECKMAN ACCESS2 chemiluminescent immunoanalyzer. The present work provides an AMI diagnostic method with high sensitivity, good repeatability, high accuracy and simple operation, which can satisfy the needs of clinical diagnosis, and shows promising application prospects.

Ultrasimple size encoded microfluidic chip for rapid simultaneous multiplex detection of DNA sequences

Simultaneous multiplexed analysis can provide comprehensive information for disease diagnosis. However, the current multiplex methods rely on sophisticated barcode technology, which hinders its wider application. In this study, an ultrasimple size encoding method is proposed for multiplex detection using a wedge-shaped microfluidic chip. Driving by negative pressure, microparticles are naturally arranged in distinct stripes based on their sizes within the chip. This size encoding method demonstrates a high level of precision, allowing for accuracy in distinguishing 3–5 sizes of microparticles with a remarkable accuracy rate of up to 99%, even the microparticles with a size difference as small as 0.5 μm. The entire size encoding process is completed in less than 5 min, making it ultrasimple, reliable, and easy to operate. To evaluate the function of this size encoding microfluidic chip, three commonly co-infectious viruses’ nucleic acid sequences (including complementary DNA sequences of HIV and HCV, and DNA sequence of HBV) are employed for multiplex detection. Results indicate that all three DNA sequences can be sensitively detected without any cross-interference. This size-encoding microfluidic chip-based multiplex detection method is simple, rapid, and high-resolution, its successful application in serum samples renders it highly promising for potential clinical promotion.

Numerical studies of manipulation and separation of microparticles in ODEP-based microfluidic chips.

A novel optical-induced dielectrophoresis (ODEP) method employing a pressure-driven flow for the continuous separation of microparticles is presented in this study. By applying alternate current electric field on conductive indium tin oxide substrate and projecting the light geometry into the photoconductive layer, an inhomogeneous electric field is locally induced. The particles experience the dielectrophoretic force when passing through the lighting area, where the strongest electrical field gradient exists. By optimizing the structure of the lighting pattern, a stronger nonuniform electric field gradient is generated which predicts the separation of 1 and 3µm polystyrene particles. Moreover, the effects of key parameters, including the light pattern geometry, applied voltage, and flow rate, were investigated in this study, leading to the successful sorting of 700nm and 1µm particles. To further examine the separation sensitivity and practicability of the proposed ODEP microfluidic method, the isolation of two different types of circulating tumor cells from T-cells and red blood cells are demonstrated, providing a novel method for the manipulation and separation of microparticles and nanoparticles.

Establishment of a Microfluidic Chip Based Rapid Detection Method for <i>Wasmannia auropunctata</i>

Invasive alien ants are one of the most aggressive, competitive, and widespread invasive alien species around the world. <i>Wasmannia auropunctata, </i>native to the neotropical zoogeographic area, has been inadvertently introduced all over the world. The first disclosed record of field establishment of <i>W. auropunctata</i> in Chinese mainland was reported in 2022. In this paper, we aim to establish a rapid detection method targeting the <i>W. auropunctata </i>polymorphic microsatellite locus Waur-275, based on the microfluidic chip technology, to contribute to an active response to the crisis caused by this invasive pest. Eight primer sets were generated using the PrimerExplorer v5 online service, and the fifth primer set selected had the lowest Ct in the volume ratio of 8 (FIP/BIP:F3/B3). Method validity with six <i>W. auropunctata </i>samples confirmed the efficiency of this assay. High specificity was demonstrated by the positive result for <i>W. auropunctata</i> out of 6 related insect samples tested. Sensitivity analysis showed that this microfluidic chip method could achieve the detection limit of 1.00×10<sup>1</sup> copies/μL. A rapid screening method is essential for the whole process of interception and control of <i>W. auropunctata </i>in China. It can also help determine the origin of invasion, clarify the path of introduction to ensure biosecurity, and also uncover other possible undetected establishments in the wild.