Lipid-Oriented Live-Cell Distinction of B and T Lymphocytes.

The identification of each cell type is essential for understanding multicellular communities. Antibodies set as biomarkers have been the main toolbox for cell-type recognition, and chemical probes are emerging surrogates. Herein we report the first small-molecule probe, CDgB, to discriminate B lymphocytes from T lymphocytes, which was previously impossible without the help of antibodies. Through the study of the origin of cell specificity, we discovered an unexpected novel mechanism of membrane-oriented live-cell distinction. B cells maintain higher flexibility in their cell membrane than T cells and accumulate the lipid-like probe CDgB more preferably. Because B and T cells share common ancestors, we tracked the cell membrane changes of the progenitor cells and disclosed the dynamic reorganization of the membrane properties over the lymphocyte differentiation progress. This study casts an orthogonal strategy for the small-molecule cell identifier and enriches the toolbox for live-cell distinction from complex cell communities.

Altered red blood cell deformability-A novel hypothesis for retinal microangiopathy in diabetic retinopathy.

PURPOSE: Impaired red blood cell (RBC) deformability impedes tissue perfusion. This study aims to investigate RBC biomechanics in type 2 diabetes mellitus (DM) patients with different grades of diabetic retinopathy (DR) and to correlate RBC deformability with hematological and serum biochemical markers. METHODS: This cross-sectional study included 86 type 2 DM patients (31 with no DR, 31 with non-proliferative DR [NPDR] and 24 with proliferative DR [PDR]) and 32 control subjects. RBC deformability was measured by a microfluidic cross-slot channel (elongation index, EI). Venous blood samples were taken for assessment of hematological and serum biochemical markers. RESULTS: RBC deformability showed significant reduction in diabetic patients, being lowest in the PDR group, followed by NPDR and DM with no DR groups, and highest in control group (P = .018). RBC deformability was not affected by age or gender but showed significant associations with certain hematological and serum biochemical markers. In the regression analysis controlling for DM status, urea concentration and reticulocyte count were shown to be negatively associated with EI. CONCLUSION: Impaired RBC deformability measured by a microfluidic cross-slot channel in DM patients with different grades of DR underscores the contribution of RBC rheological properties to the pathogenesis and progression of DM related microangiopathy.

Biomimetic Precapillary Flow Patterns for Enhancing Blood Plasma Separation: A Preliminary Study.

In this study, a biomimetic microfluidic plasma separation device is discussed. The design of the device drew inspiration from in vivo observations of enhanced cell-free layer (CFL) formation downstream of vascular bifurcations. The working principle for the plasma separation was based on the plasma skimming effect in an arteriolar bifurcation, which is modulated by CFL formation. The enhancement of the CFL width was achieved by a local hematocrit reduction near the collection channel by creating an uneven hematocrit distribution at the bifurcation of the channel. The device demonstrated a high purity of separation (~99.9%) at physiological levels of hematocrit (~40%).

Blood-Brain Barrier-Targeting Nanoparticles: Biomaterial Properties and Biomedical Applications in Translational Neuroscience.

Overcoming the blood-brain barrier (BBB) remains a significant hurdle in effective drug delivery to the brain. While the BBB serves as a crucial protective barrier, it poses challenges in delivering therapeutic agents to their intended targets within the brain parenchyma. To enhance drug delivery for the treatment of neurological diseases, several delivery technologies to circumvent the BBB have been developed in the last few years. Among them, nanoparticles (NPs) are one of the most versatile and promising tools. Here, we summarize the characteristics of NPs that facilitate BBB penetration, including their size, shape, chemical composition, surface charge, and importantly, their conjugation with various biological or synthetic molecules such as glucose, transferrin, insulin, polyethylene glycol, peptides, and aptamers. Additionally, we discuss the coating of NPs with surfactants. A comprehensive overview of the common in vitro and in vivo models of the BBB for NP penetration studies is also provided. The discussion extends to discussing BBB impairment under pathological conditions and leveraging BBB alterations under pathological conditions to enhance drug delivery. Emphasizing the need for future studies to uncover the inherent therapeutic properties of NPs, the review advocates for their role beyond delivery systems and calls for efforts translating NPs to the clinic as therapeutics. Overall, NPs stand out as a highly promising therapeutic strategy for precise BBB targeting and drug delivery in neurological disorders.

Application of machine learning algorithms for accurate determination of bilirubin level on in vitro engineered tissue phantom images.

Neonatal Jaundice is a common occurrence in neonates. High excess bilirubin would lead to hyperbilirubinemia, leading to irreversible adverse damage such as kernicterus. Therefore, it is necessary and important to monitor neonates' bilirubin levels in real-time for immediate intervention. However, current screening protocols have their inherent limitations, necessitating more convenient measurements. In this proof-of-concept study, we evaluated the feasibility of using machine learning for the screening of hyperbilirubinemia in neonates from smartphone-acquired photographs. Different machine learning models were compared and evaluated to gain a better understanding of feature selection and model performance in bilirubin determination. An in vitro study was conducted with a bilirubin-containing tissue phantom to identify potential biological and environmental confounding factors. The findings of this study present a systematic characterization of the confounding effect of various factors through separate parametric tests. These tests uncover potential techniques in image pre-processing, highlighting important biological features (light scattering property and skin thickness) and external features (ISO, lighting conditions and white balance), which together contribute to robust model approaches for accurately determining bilirubin concentrations. By obtaining an accuracy of 0.848 in classification and 0.812 in regression, these findings indicate strong potential in aiding in the design of clinical studies using patient-derived images.

A hand-targeted auxiliary personal protective equipment for intervention of fomite transmission of viruses.

In COVID-19, fomite transmission has been shown to be a major route for the spreading of the SARS-CoV-2 virus due to its ability to remain on surfaces for extended durations. Although glove wearing can mitigate the risk of viral transmission especially on high touch points, it is not prevalent due to concerns on diversion of frontline medical resources, cross-contamination, social stigma, as well as discomfort and skin reactions derived from prolonged wearing. In this study, we developed FlexiPalm, a hand-targeted auxiliary personal protective equipment (PPE) against fomite transmission of viruses. FlexiPalm is a unique palmar-side hand protector designed to be skin-conforming and transparent, fabricated from medical-grade polyurethane transparent film material as a base substrate. It serves primarily as a barrier to microbial contamination like conventional gloves, but with augmented comfort and inconspicuousness to encourage a higher public adoption rate. Compared to conventional glove materials, FlexiPalm demonstrated enhanced mechanical durability and breathability, comparable hydrophobicity, and displayed a minimal adsorption of SARS-CoV-2 spike protein and virus-like particles (VLP). Importantly, FlexiPalm was found to bind significantly less viral protein and VLP than artificial human skin, confirming its ability to reduce viral contamination. A pilot study involving participants completing activities of daily living showed a high level of comfort and task completion, illustrating the usability and functionality of FlexiPalm. Moreover, we have demonstrated that surface modification of FlexiPalm with microtextures enables further reduction in viral adsorption, thereby enhancing its functionality. An effective implementation of FlexiPalm will bolster PPE sustainability and lead to a paradigm shift in the global management of COVID-19 and other infectious diseases in general.

Assessment of transient changes in oxygen diffusion of single red blood cells using a microfluidic analytical platform.

Red blood cells (RBCs) capability to deliver oxygen (O2) has been routinely measured by P50. Although this defines the ability of RBCs to carry O2 under equilibrium states, it cannot determine the efficacy of O2 delivery in dynamic blood flow. Here, we developed a microfluidic analytical platform (MAP) that isolates single RBCs for assessing transient changes in their O2 release rate. We found that in vivo (biological) and in vitro (blood storage) aging of RBC could lead to an increase in the O2 release rate, despite a decrease in P50. Rejuvenation of stored RBCs (Day 42), though increased the P50, failed to restore the O2 release rate to basal level (Day 0). The temporal dimension provided at the single-cell level by MAP could shed new insights into the dynamics of O2 delivery in both physiological and pathological conditions.

Vibration motor-integrated low-cost, miniaturized system for rapid quantification of red blood cell aggregation.

Human red blood cells (RBCs) aggregate under low shear conditions, which significantly modulates flow resistance and tissue perfusion. A higher aggregation tendency in blood thus serves as an important clinical indicator for the screening of cardiovascular disorders. Conventional ways of measuring RBC aggregation still require large sample volumes, cumbersome manual procedures, and expensive benchtop systems. These inconvenient and high-cost measurement methods hamper their clinical applicability. Here, we propose a low-cost, miniaturized system to overcome the limitations of these methods. Our system utilizes a coin vibration motor (CVM) to generate a localized vortex for disaggregating RBCs in a disposable fluidic chip. The design of the chip was optimized with fluid dynamics simulations to ensure sufficient shear flow in the localized vortex for RBC disaggregation. The time-dependent increase in light transmittance from an LED light source through the plasma gap while the RBCs re-aggregate is captured with a CMOS camera under stasis conditions to quantify the level of RBC aggregation. Our CVM-based aggregometer was validated against a commercial benchtop system for human blood samples under physiological and pathological conditions, and showed an excellent performance with a high intraclass correlation coefficient of 0.995. In addition, we were able to achieve a rapid measurement (<4 min) with the CVM-based aggregometer, requiring only a 6 µl blood sample. These illustrate the potential of our CVM-based aggregometer for low-cost point-of-care diagnostics without compromising the measurement sensitivity.

High-throughput malaria parasite separation using a viscoelastic fluid for ultrasensitive PCR detection.

A novel microfluidic device for high-throughput particle separation using a viscoelastic fluid, which enables the rapid detection of extremely rare malaria parasites by using PCR analysis, is proposed. Our device consists of two segments: the 1st stage for sheathless pre-alignment and the 2nd stage for separation based on size-dependent viscoelasticity-induced lateral migration. The use of a high-aspect ratio channel and a viscoelastic polymer solution with low viscosity enables high-throughput processing. The device performance was first optimized using synthetic particles. A mixture of 2 and 10 µm particles was focused at the center plane in the 1st stage. The smaller particles, serving as surrogates for malaria parasites, were subsequently separated in the 2nd stage with a recovery rate of ∼96% at 400 µl min(-1). Finally, separation of the malaria parasites from the white blood cells was performed. At 400 µl min(-1), almost all white blood cells were removed and the malaria parasites were separated with a ∼94% recovery rate and ∼99% purity. Although the initial concentration of the malaria parasites was too low to be detected by PCR analysis, WBC depletion and buffer removal increased the parasite concentration sufficiently such that PCR detection was possible.

Hybrid capillary-inserted microfluidic device for sheathless particle focusing and separation in viscoelastic flow.

A novel microfluidic device which consists of two stages for particle focusing and separation using a viscoelastic fluid has been developed. A circular capillary tube was used for three-dimensional particle pre-alignment before the separation process, which was inserted in a polydimethylsiloxane microchannel. Particles with diameters of 5 and 10 µm were focused at the centerline in the capillary tube, and the location of particles was initialized at the first bifurcation. Then, 5 and 10 µm particles were successfully separated in the expansion region based on size-dependent lateral migration, with ∼99% separation efficiency. The proposed device was further applied to separation of MCF-7 cells from leukocytes. Based on the cell size distribution, an approximate size cutoff for separation was determined to be 16 µm. At 200 µl/min, 94% of MCF-7 cells were separated with the purity of ∼97%. According to the trypan blue exclusion assay, high viability (∼90%) could be achieved for the separated MCF-7 cells. The use of a commercially available capillary tube enables the device to be highly versatile in dealing with particles in a wide size range by using capillary tubes with different inner diameters.