Breakthrough in purification of fossil pollen for dating of sediments by a new large-particle on-chip sorter

Particle sorting is a fundamental method in various fields of medical and biological research. However, existing sorting applications are not capable for high-throughput sorting of large-size (>100 micrometers) particles. Here, we present a novel on-chip sorting method using traveling vortices generated by on-demand microjet flows, which locally exceed laminar flow condition, allowing for high-throughput sorting (5 kilohertz) with a record-wide sorting area of 520 micrometers. Using an activation system based on fluorescence detection, the method successfully sorted 160-micrometer microbeads and purified fossil pollen (maximum dimension around 170 micrometers) from lake sediments. Radiocarbon dates of sorting-derived fossil pollen concentrates proved accurate, demonstrating the method’s ability to enhance building chronologies for paleoenvironmental records from sedimentary archives. The method is capable to cover urgent needs for high-throughput large-particle sorting in genomics, metabolomics, and regenerative medicine and opens up new opportunities for the use of pollen and other microfossils in geochronology, paleoecology, and paleoclimatology.

PGC1/PPAR drive cardiomyocyte maturation at single cell level via YAP1 and SF3B2

Cardiomyocytes undergo significant structural and functional changes after birth, and these fundamental processes are essential for the heart to pump blood to the growing body. However, due to the challenges of isolating single postnatal/adult myocytes, how individual newborn cardiomyocytes acquire multiple aspects of the mature phenotype remains poorly understood. Here we implement large-particle sorting and analyze single myocytes from neonatal to adult hearts. Early myocytes exhibit wide-ranging transcriptomic and size heterogeneity that is maintained until adulthood with a continuous transcriptomic shift. Gene regulatory network analysis followed by mosaic gene deletion reveals that peroxisome proliferator-activated receptor coactivator-1 signaling, which is active in vivo but inactive in pluripotent stem cell-derived cardiomyocytes, mediates the shift. This signaling simultaneously regulates key aspects of cardiomyocyte maturation through previously unrecognized proteins, including YAP1 and SF3B2. Our study provides a single-cell roadmap of heterogeneous transitions coupled to cellular features and identifies a multifaceted regulator controlling cardiomyocyte maturation.

Microfluidic Devices for Magnetic Separation of Biological Particles: A Review

Separation of microparticles and cells serves a critical step in many applications such as in biological analyses, food production, chemical processing, and medical diagnostics. Sorting on the microscale exhibits certain advantages in comparison with that on the macroscale as it requires minuscule sample or reagents volume and thus reduced analysis cycle time, smaller size of devices, and lower fabrication costs. Progresses have been made over time to improve the efficiency of these microscale particle manipulation techniques. Many different techniques have been used to attain accurate particle sorting and separation in a continuous manner on the microscale level, which can be categorized as either passive or active methods. Passive techniques achieve accurate manipulation of particles through their interaction with surrounding flow by carefully designed channel structures, without using external fields. As an alternative, active techniques utilize external fields (e.g., acoustic, electronic, optical, and magnetic field, etc.) to realize desired pattern of motion for particles with specific properties. Among numerous active methods for microfluidic particle sorting, the magnetic field has been widely used in biomedical and chemical applications to achieve mixing, focusing, and separating of reagents and bioparticles. This paper aims to provide a thorough review on the classic and most up-to-date magnetic sorting and separation techniques to manipulate microparticles including the discussions on the basic concept, working principle, experimental details, and device performance.

Numerical Study on the Influence of Microchannel’s Geometry on Sub-Micron Particles Separation Using Acoustophoresis

Application of acoustophoresis to cell and particle separation in microchannel filled with fluid medium has been drawing increasing attention in many disciplines in the past decades due to its high precision and minimum damage to the matters of interest. Previous studies on particle separation often rely on the size-dependent feature of the acoustic radiation force (ARF), while the acoustic streaming effect (ASE) is a hurdle as the particle size goes down. Sub-micron particles circulate according to the streaming vortices and become inseparable from the particles settled on the pressure node. Instead of suppressing the ASE, this study intends to utilize the combined effect of ARF and ASE on sub-micron particle sorting by altering the microchannel’s cross-sectional shapes. The roles of ARF and ASE on particles with 0.2um and 2um in radius in various cross-sectional shapes are studied numerically. The studied geometries include 1. rectangular, 2. trapezoidal, and 3. triangular. The results show that changing the cross-sectional shapes affects the acoustic field’s magnitude and distribution, the streaming patterns, the magnitude of streaming velocity, and the movement of sub-micron particles. In non-rectangular microchannel, sub-micron particles circulate towards and settle at the center of the streaming vortices. This phenomenon shows the potential to manipulate the streaming-dominant particles, thereby enhancing the acoustophoretic particle sorting performance.