Combined CD25, CD64, and CD69 Biomarker in 3D-Printed Multizone Millifluidic Device for Sepsis Detection in Clinical Samples.

Sepsis is a serious medical condition that arises from a runaway response to an infection, which triggers the immune system to release chemicals into the bloodstream. This immune response can result in widespread inflammation throughout the body, which may cause harm to vital organs and, in more severe cases, lead to organ failure and death. Timely and accurate diagnosis of sepsis remains a challenge in analytical diagnostics. In this work, we have developed and validated a sepsis detection device, utilizing 3D printing technology, which incorporates multiple affinity separation zones. Our device requires minimal operator intervention and utilizes CD64, CD69, and CD25 as the biomarker targets for detecting sepsis in liquid biopsies. We assessed the effectiveness of our 3D-printed multizone cell separation device by testing it on clinical samples obtained from both septic patients (n = 35) and healthy volunteers (n = 8) and validated its performance accordingly. Unlike previous devices using poly(dimethyl siloxane), the 3D-printed device had reduced nonspecific binding for anti-CD25 capture, allowing this biomarker to be assayed for the first time in cell separations. Our results showed a statistically significant difference in cell capture between septic and healthy samples (with p values of 0.0001 for CD64, CD69, and CD25), suggesting that 3D-printed multizone cell capture is a reliable method for distinguishing sepsis. A receiver operator characteristic (ROC) analysis was performed to determine the accuracy of the captured cell counts for each antigen in detecting sepsis. The ROC area under the curve (AUC) values for on-chip detection of CD64+, CD69+, and CD25+ leukocytes were 0.96, 0.92, and 0.88, respectively, indicating our diagnostic test matches clinical outcomes. When combined for sepsis diagnosis, the AUC value for CD64, CD69, and CD25 was 0.99, indicating an improved diagnostic performance due to the use of multiple biomarkers.

High-recovery sorting of cancer cells from whole blood via periodic-focusing inertial microchip.

Inertial microfluidic devices continue to show promise for label-free separation of cells from liquid biopsies and other biological samples. Serpentine-channel microfluidic devices capitalizing on inertial forces such as Dean flow have been demonstrated for cell separation, but are limited in performance due to the magnitude of the inertial lift and drag force gradients across the separation channel. We have developed a new flow design that uses periodic channel contractions to enhance the magnitude of the force gradient. Separation recover was 97% with the final sorter output consisting of 78% target cells. Separation efficiency was 87% for whole blood, which could be increased to 97% if the sample was diluted prior to sorting. The enrichment of cancer cells was over 1000-fold, and sorted cancer cells maintained a viability of 93.8% for 96 hours after sorting. In the analysis of blood plasma, breast cancer cells from a clinical patient were enriched 20×. The incorporation of periodic channel contractions in a Dean flow circuit resulted in an increase in Dean flow gradient according to simulation, resulting in sorting of small-diameter cancer cells in blood samples.

A comparison of transferrin-receptor and epithelial cellular adhesion molecule targeting for microfluidic separation of cancer cells.

Microfluidic, flow cytometry, and immunomagnetic methods for cancer cell isolation have heavily relied on the Epithelial Cellular Adhesion Molecule (EpCAM) for affinity separation. While EpCAM has been used extensively for circulating tumor cell isolation, it cannot be used to isolate non-epithelial cells. The human transferrin receptor (CD71) can also be used for cancer cell isolation and has the advantage that as an affinity target it can separate virtually any cancer cell type, regardless of disease origin. However, direct comparison of the capture ability of EpCAM and CD71 has not been reported previously. In this work, cell capture with both EpCAM and CD71 were studied using a novel higher-throughput herringbone cell separation microfluidic device. Five separation chip models were designed and the one with the highest capture efficiency (average 90 ± 10%) was chosen to compare antigen targets for cell capture. Multiple cancer cell lines including CCRF-CEM, PC-3 and MDA-MB-231 were tested for cell capture performance using both ligands (anti-CD71 and anti-EpCAM) in the optimized chip design. PC-3 and MDA-MB-231 cells were spiked into blood at concentrations ranging from 0.5%-10%. PC-3 cells were separated by anti-CD71 and anti-EpCAM with 32-37% and 31-50% capture purity respectively, while MDA-MB-231 were separated with 35-53% and 33-56% capture purity using anti-CD71 and anti-EpCAM for all concentrations. The enrichment factor for the lowest concentrations of cells in blood ranged from 66-74X. The resulting enrichment of cancer cells shows that anti-CD71 was found to be statistically similar to anti-EpCAM for epithelial cancer cells, while anti-CD71 can be further used for non-epithelial cells, where anti-EpCAM cannot be used.

Microfluidics for sepsis early diagnosis and prognosis: a review of recent methods.

Sepsis is a complex disorder of immune system response to infections that can be caused by a wide range of clinical contexts. Traditional methods for sepsis detection include molecular diagnosis, biomarkers either based on protein concentration or cell surface expression, and microbiological cultures. Development of point-of-care (POC) instruments, which can provide high accuracy and consume less time, is in unprecedented demand. Within the past few years, applications of microfluidic systems for sepsis detection have achieved excellent performance. In this review, we discuss the most recent microfluidic applications specifically in sepsis detection, and propose their advantages and disadvantages. We also present a comprehensive review of other traditional and current sepsis diagnosis methods to obtain a general understanding of the present conditions, which can hopefully direct the development of a new sepsis roadmap.

A fluorescence toolbox: A review of investigation of electrophoretic separations, process, and interfaces.

This review focuses on fluorescence spectroscopy techniques for the investigation of electrophoretic separations. Fluorescence has been used as a sensitive detector for capillary, gel, and microchip electrophoresis for decades. However, advanced fluorescence methods can be used to study transport, interfacial phenomena, intermolecular and affinity interactions, and other processes that occur during separation. This so-called spectroscopic toolkit can be implemented to understand fundamental behavior in electrophoresis and electrokinetic chromatography. Techniques such as fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, and fluorescence anisotropy are discussed in relation to electrophoretic separations. Newer methods such as super-resolution microscope are also introduced.

Affinity separation and subsequent terminal differentiation of acute myeloid leukemia cells using the human transferrin receptor (CD71) as a capture target.

The microfluidic detection of myeloblasts in blood via the human transferrin receptor (CD71) can serve as a diagnostic marker for acute myeloid leukemia (AML). Furthermore, CD71 expression is present in all proliferating cells and can capture target cells without prior knowledge of AML subtype. The use of anti-CD71 as the affinity ligand for AML detection in this work yields a capture efficiency and purity during peak CD71 expression of 92% and 62%, respectively. Additionally, target cells were isolated from lysed, preserved blood samples with a capture purity of 32% at a concentration of 10% myeloblasts in blood, half of the current diagnosis threshold determined by the World Health Organization. Cells isolated using this capture ligand were then subjected to post-separation differentiation therapy. HL60 cells were differentiated into non-proliferating, neutrophil-like cells. After 48 hours of incubation with 1.5% DMSO, there was a decrease in the CD71 antigen expression in differentiated cells. This separation approach can be used to screen blood samples for AML cells, and the effluent of the separation is available for post-separation analyses.

Nanoparticle modification of microfluidic cell separation for cancer cell detection and isolation.

Cancer is a major health problem in the United States with extremely high mortality. The detection and isolation of cancer cells are becoming increasingly important for cancer diagnosis. We describe a microfluidic device modified with silica nanoparticles to enhance the isolation of cancer cells using affinity separation. The isolation of seven different cancer cell lines spiked into liquid biopsies was demonstrated and compared with unmodified separation devices. Cancer cells were isolated using CD71 which has already been demonstrated to be a widespread "net" for capturing cancer cells of any phenotype as the affinity target. The capture efficiency of our nanoparticle (NP)-modified HB chip showed significant differences compared with the normal HB chip, exhibiting an average increase of 16%. The cell enrichment increased by a factor of 2 over unmodified chips. Patient-derived ALL cells, COG-LL-332, were spiked into blood with concentrations ranging from 1% to 20% of total leukocytes, and isolated with the purity of 41%-65%. The results of this study demonstrated that the increase of cell-chip interactions after nanoparticle modification improved capture efficiency and capture purity, and can be applied to a wide range of cell separations.

Modulation and study of photoblinking behavior in dye doped silver-silica core-shell nanoparticles for localization super-resolution microscopy.

Blinking of fluorescent nanoparticles is a compelling phenomenon with widely debated mechanisms. The ability to inhibit or control blinking is important for applications in the field of optical, semiconductor and fluorescent imaging. Self-blinking nanomaterials are also attractive labels for localization-based super-resolution microscopy. In this work, we have synthesized silver core silica nanoparticles (Ag@SiO2) doped with Rhodamine 110 and studied the parameters that affect blinking. We found that under nitrogen rich conditions the nanoparticles shifted towards higher duty cycles. Also, it was found that hydrated nanoparticles showed a less drastic response to nitrogen rich conditions as compared to dried nanoparticles, indicating that surrounding matrix played a role in the response of nanoparticles to molecular oxygen. Further, the blinking is not a multi-body phenomena, super-resolution localization combined with intensity histogram analysis confirmed that single particles are emitting.

Multiparameter Affinity Microchip for Early Sepsis Diagnosis Based on CD64 and CD69 Expression and Cell Capture.

Sepsis is a leading cause of death worldwide. In this work, a multiparameter affinity microchip was developed for faster sepsis diagnosis, which can reduce the mortality caused by late validation. The separation device captured cells expressing CD25, CD64, and CD69 into discrete antibody regions. The performance of multiparameter cell separation microchips was compared with flow cytometry analysis and validated with samples of septic patients ( n = 15) and healthy volunteers ( n = 10). The total analysis time was 2 h. Results showed that total on-chip cell counts for both CD64 and CD69 regions were linear with antigen expression levels. The difference between cell capture for septic and healthy samples was statistically significant (CD64: p = 0.0033; CD69: p = 0.0221, 95% confidence interval), indicating that sepsis is distinguishable based on microfluidic cell capture. For on-chip detection of CD64+ and CD69+ leukocytes, the AUC was 0.95 and 0.78, respectively. The combination of CD64 and CD69 for sepsis diagnosis had the AUC of 0.98, indicating the improved and excellent diagnostic performance of multiple parameters.

Fundamentals of affinity cell separations.

Cell separations using affinity methods continue to be an enabling science for a wide variety of applications. In this review, we discuss the fundamental aspects of affinity separation, including the competing forces for cell capture and elution, cell-surface interactions, and models for cell adhesion. Factors affecting separation performance such as bond affinity, contact area, and temperature are presented. We also discuss and demonstrate the effects of nonspecific binding on separation performance. Metrics for evaluating cell separations are presented, along with methods of comparing separation techniques for cell isolation using affinity capture.

Microfluidic Separation of Lymphoblasts for the Isolation of Acute Lymphoblastic Leukemia Using the Human Transferrin Receptor as a Capture Target.

Acute lymphocytic leukemia (ALL) is the most prevalent pediatric cancer, and the peripheral blood lymphoblast percentage is an important index for ALL diagnosis and prognosis. We describe a microfluidic device that isolates and enumerates peripheral blood lymphoblasts using affinity separations. The innovative use of a nonspecific ligand allows a widespread "net" for cancer cells, without a priori knowledge of the cancer type. Using lymphoblasts spiked into blood, we simulated leukemia cases with lymphoblast concentrations ranging from 1 to 30% of total leukocytes. Lymphoblasts were isolated using monoclonal antibodies for the Human Transferring Receptor (CD71). Anti-CD71 antibodies were found to be more effective for capturing lymphoblasts than commonly used, ALL-specific antibodies for CD7 and CD10. CCRF-CEM lymphoblasts were isolated in the chip with 82-97% purity, with lower concentrations tested (7%) still showing >80% purity for cell capture. Patient-derived ALL cell lines COG-LL-332 and COG-LL-317 were isolated in the chip with 80%-97% and 57% -92% of purity, respectively, with the initial spike concentrations as low as 1%. The ability to capture ALL lymphoblasts present in blood at low concentrations provides a novel approach for characterization of ALL cells, including patients with low leukemic burdens during and after therapy.

Detection of sepsis in patient blood samples using CD64 expression in a microfluidic cell separation device.

A microfluidic affinity separation device was developed for the detection of sepsis in critical care patients. An affinity capture method was developed to capture cells based on changes in CD64 expression in a single, simple microfluidic chip for sepsis detection. Both sepsis patient samples and a laboratory CD64+ expression model were used to validate the microfluidic assay. Flow cytometry analysis showed that the chip cell capture had a linear relationship with CD64 expression in laboratory models. The Sepsis Chip detected an increase in upregulated neutrophil-like cells when the upregulated cell population is as low as 10% of total cells spiked into commercially available aseptic blood samples. In a proof of concept study, blood samples obtained from sepsis patients within 24 hours of diagnosis were tested on the chip to further validate its performance. On-chip CD64+ cell capture from 10 patient samples (619 ± 340 cells per chip) was significantly different from control samples (32 ± 11 cells per chip) and healthy volunteer samples (228 ± 95 cells per chip). In addition, the on-chip cell capture has a linear relationship with CD64 expression indicating our approach can be used to measure CD64 expression based on total cell capture on Sepsis Chip. Our method has proven to be sensitive, accurate, rapid, and cost-effective. Therefore, this device is a promising detection platform for neutrophil activation and sepsis diagnosis.

Microfluidics and cancer analysis: cell separation, cell/tissue culture, cell mechanics, and integrated analysis systems.

Among the growing number of tools available for cancer studies, microfluidic systems have emerged as a promising analytical tool to elucidate cancer cell and tumor function. Microfluidic methods to culture cells have created approaches to provide a range of environments from single-cell analysis to complex three-dimensional devices. In this review we discuss recent advances in tumor cell culture, cancer cell analysis, and advanced studies enabled by microfluidic systems.

Microfluidic cell surface antigen expression analysis using a single antibody type.

Antigen expression plays a significant role in clinical studies, pathology, biology and chemistry. The type and degree of antigen expression can provide information for disease diagnosis/monitoring and is used for phenotype analysis of cells. In this work, an affinity capture method was developed to capture cells based on antigen expression differences in a single microfluidic chip. Microfluidic chips with two affinity regions-at different antibody concentrations-captured two cell types based on differences in the expression of a single antigen. Using herringbone-modified capture channels, a separation purity of 95% and a capture efficiency of 15% were achieved under continuous-flow conditions. We observed that the capture ratio of Ramos B lymphocytes and HuT 78 T lymphocytes matched the expression ratio of CD71 for the two cell lines (R(2) = 0.94). To further validate our analytical method, Ramos B lymphocytes were spiked into blood samples to demonstrate performance with a complex sample. Expression ratios matched conventional flow cytometry measurements over a 40-fold difference, and the sample enrichment was 9.5×. This method has proven to be a robust system to measure the differences in antigen expression, and can be used to distinguish cells without having a unique surface antigen if the expression level is sufficiently high in one cell type.

A complementary method to CD4 counting: measurement of CD4+/CD8+ T lymphocyte ratio in a tandem affinity microfluidic system.

We describe a tandem affinity microfluidic separation that measures the ratio of CD4+/CD8+ T lymphocytes from blood samples. It is performed by injecting 2 µL of lysed blood samples at 1800-2700 cells µL(-1) into a microfluidic device containing two serially linked affinity regions, followed with a stop flow incubation that captures CD4+/CD8+ T lymphocytes on the corresponding affinity regions. Fluorophore conjugated antibodies are then injected at a controlled shear stress of 1.7 dyn cm(-2) to label target cells while eluting non-specific cells; and at last the CD4/CD8 ratio is calculated after the cell enumeration. The ratio of CD4+/CD8+ T lymphocytes achieved by our tandem affinity microfluidic system was in close agreement with that performed using conventional flow cytometry (R (2) = 0.97) over a wide range (0.4-2.5) that covered the reference values from immune deficient patients to healthy people. This approach may represent an inexpensive and powerful tool in diagnosis of immunodeficiency disorders including HIV or mycobacterium tuberculosis.

On-chip gradient generation in 256 microfluidic cell cultures: simulation and experimental validation.

A microfluidic diffusion diluter was used to create a stable concentration gradient for dose response studies. The microfluidic diffusion diluter used in this study consisted of 128 culture chambers on each side of the main fluidic channel. A calibration method was used to find unknown concentrations with 12% error. Flow rate dependent studies showed that changing the flow rates generated different gradient patterns. Mathematical simulations using COMSOL Multi-physics were performed to validate the experimental data. The experimental data obtained for the flow rate studies agreed with the simulation results. Cells could be loaded into culture chambers using vacuum actuation and cultured for long times under low shear stress. Decreasing the size of the culture chambers resulted in faster gradient formation (20 min). Mass transport into the side channels of the microfluidic diffusion diluter used in this study is an important factor in creating the gradient using diffusional mixing as a function of the distance. To demonstrate the device's utility, an H2O2 gradient was generated while culturing Ramos cells. Cell viability was assayed in the 256 culture chambers, each at a discrete H2O2 concentration. As expected, the cell viability for the high concentration side channels increased (by injecting H2O2) whereas the cell viability in the low concentration side channels decreased along the chip due to diffusional mixing as a function of distance. COMSOL simulations were used to identify the effective concentration of H2O2 for cell viability in each side chamber at 45 min. The gradient effects were confirmed using traditional H2O2 culture experiments. Viability of cells in the microfluidic device under gradient conditions showed a linear relationship with the viability of the traditional culture experiment. Development of the microfluidic device used in this study could be used to study hundreds of concentrations of a compound in a single experiment.

Probing hypoxia-induced staurosporine resistance in prostate cancer cells with a microfluidic culture system.

A microfluidic system for cell culture and drug response studies was developed to elucidate the effects of hypoxia on drug susceptibility. Drug response studies were performed in prostate cancer cells and Ramos B cells under normoxic and hypoxic conditions. A vacuum actuated microfluidic culture device was used for cell culture and PC3 cells were cultured in the chip up to 16 hours. Cells were treated with several concentrations of staurosporine and apoptosis was assayed using the fluorescent probes MitoTracker Deep Red and Annexin-V. For hypoxic samples, the chip was placed in a hypoxia chamber and pre-conditioned at <1% oxygen before inducing the cells with staurosporine. Cells exposed to 2 µM staurosporine were 32% ± 10% apoptotic under normoxic conditions but only 1.5% ± 12% apoptotic under hypoxic conditions. As little as 1 hour of hypoxic preconditioning increased drug resistance. Cell apoptosis correlated with drug dose, although in each case hypoxia reduced the apoptotic fraction significantly. Given the rapid nature of cell adaptation to hypoxia, this chip and analysis approach can be used to identify compounds that can induce cell death in hypoxic tumor cells rapidly.

Microfluidic antibody arrays for simultaneous cell separation and stimulus.

A microfluidic chip containing stamped antibody arrays was developed for simultaneous cell separation and drug testing. Poly(dimethyl siloxane) (PDMS) stamping was used to deposit antibodies in a microfluidic channel, forming discrete cell-capture regions on the surface. Cell mixtures were then introduced, resulting in the separation of cells when specific antibodies were used. Anti-CD19 antibody regions resulted in 94 % capture purity for CD19+ Ramos cells. An antibody that captures multiple cell types, for example anti-CD71, can also be used to capture several cell types simultaneously. Cells could also be loaded onto the arrays with spatial control using laminar streams. Both Ramos B cells and HuT 78 T cells were isolated in the chip and exposed to staurosporine in the same channel. Both cell lines had similar responses to the drug, with 2-10 % of cells remaining viable after 20 h of drug treatment, depending on cell type. The chip can also be used to analyze the efficacy of antibody therapy against cancer cells. Anti-CD95 was deposited on the surface and used for simultaneous cell capture and apoptosis induction via the extrinsic pathway. Cells captured on anti-CD95 surfaces had significant viability loss (15 % viability after 24 h) when compared with a control anti-CD71 antibody (81 % viability after 24 h). This chip can be used for a variety of cell separation and/or drug testing studies, enabling researchers to isolate cells and test them against different anti-cancer compounds and to follow cell response using fluorescence or other readout methods.

Cancer Cell Targeting Via Selective Transferrin Receptor Labeling Using Protein-Derived Carbon Dots.

Carbon dot (CD) nanoparticles offer tremendous advantages as fluorescent probes in bioimaging and biosensing; however, they lack specific affinity for biomolecules, limiting their practical applications in selective targeting. Nanoparticles with intrinsic affinity for a target have applications in imaging, cytometry, therapeutics, etc. Toward that end, we report the transferrin receptor (CD71) targeting CDs, synthesized for the first time. The formation of these particles is truly groundbreaking, as direct tuning of nanoparticle affinity was achieved by simple and careful precursor selection of a protein, which has the targeting characteristic of interest. We hypothesized that the retention of the original protein's peptides on the nanoparticle surface provides the CDs with some of the function of the precursor protein, enabling selective binding to the protein's receptor. This was confirmed with FTIR (Fourier transform infrared) data and subsequent affinity-based cell assays. These transferrin (Tf)-derived CDs have been shown to possess an affinity for CD71, a cancer biomarker that is ubiquitously expressed in nearly every cancer cell line due to its central role mediating the uptake of cellular iron. The CDs were tested using the human leukemia cell line HL60 and demonstrated the selective targeting of CD71 and specific triggering of transferrin-mediated endocytosis via clathrin-coated pits. The particle characterization results reflect a carbon-based nanoparticle with bright violet fluorescence and 7.9% quantum yield in aqueous solution. These unpresented CDs proved to retain the functional properties of the precursor protein. Indicating that this process can be repeated for other disease biomarkers for applications ranging from biosensing and diagnostic bioimaging to targeted therapeutics.

Anti-tumor withanolides as signal transducers and activators of transcription 3 (STAT3)-inhibition from Withania obtusifolia.

The Solanaceae family and the Withania genus specifically are rich sources of medicinal plants. Liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS/MS) revealed a predominance of withanolides from an organic extract of Withania obtusifolia. A constructed molecular network uncovered the presence of potentially novel withanolides. A series of withanolides were then isolated and structurally characterized from the extract including two new withanolides (withafolia A and withafolia B) and seven previously reported metabolites. Of the isolated compounds, cytotoxicity of withanolide J, physaperuvin G, and a commercial STAT3 inhibitor (S3I-201) were assessed against a human leukemia HL-60 cell line resulting in IC50 values of 26, 29, and 120 µM, respectively. In silico molecular docking simulations indicate that withanolide J and physaperuvin G can bind as an inhibitor in the active site of STAT3 with docking scores comparable to the selective STAT3 inhibitor, S3I-201.