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Geometry in materials is a key concept which can determine material behavior in ordering, frustration, and fragmentation. More specifically, the behavior of interacting degrees of freedom subject to arbitrary geometric constraints has the potential to be used for engineering materials with exotic phase behavior. While advances in lithography have allowed for an experimental exploration of geometry on ordering that has no precedent in nature, many of these methods are low throughput or the underlying dynamics remain difficult to observe directly. Here, we introduce an experimental system that enables the study of interacting many-body dynamics by exploiting the physics of multidroplet evaporation subject to two-dimensional spatial constraints. We find that a high-energy initial state of this system settles into frustrated, metastable states with relaxation on two timescales. We understand this process using a minimal dynamical model that simulates the overdamped dynamics of motile droplets by identifying the force exerted on a given droplet as being proportional to the two-dimensional vapor gradients established by its neighbors. Finally, we demonstrate the flexibility of this platform by presenting experimental realizations of droplet-lattice systems representing different spin degrees of freedom and lattice geometries. Our platform enables a rapid and low-cost means to directly visualize dynamics associated with complex many-body systems interacting via long-range interactions. More generally, this platform opens up the rich design space between geometry and interactions for rapid exploration with minimal resources. [ABSTRACT FROM AUTHOR]

We present periodic nanohole arrays fabricated in free-standing metal-coated nitride films as a platform for trapping and analyzing single organelles. When a microliter-scale droplet containing mitochondria is dispensed above the nanohole array, the combination of evaporation and capillary flow directs individual mitochondria to the nanoholes. Mammalian mitochondria arrays were rapidly formed on chip using this technique without any surface modification steps, microfluidic interconnects, or external power sources. The trapped mitochondria were depolarized on chip using an ionophore with results showing that the organelle viability and behavior were preserved during the on-chip assembly process. Fluorescence signal related to mitochondrial membrane potential was obtained from single mitochondria trapped in individual nanoholes revealing statistical differences between the behavior of polarized vs depolarized mammalian mitochondria. This technique provides a fast and stable route for droplet-based directed localization of organelles-on-a-chip with minimal limitations and complexity, as well as promotes integration with other optical or electrochemical detection techniques. [ABSTRACT FROM AUTHOR]

Nanopipettes are an attractive single-molecule tool for identification and characterisation of nucleic acids and proteins in solutions. They enable label-free analysis and reveal individual molecular properties, which are generally masked by ensemble averaging. Having control over the pore dimensions is vital to ensure that the dimensions of the molecules being probed match those of the pore for optimization of the signal to noise. Although nanopipettes are simple and easy to fabricate, challenges exist, especially when compared to more conventional solid-state analogues. For example, a sub-20 nm pore diameter can be difficult to fabricate and the batch-to-batch reproducibility is often poor. To improve on this limitation, atomic layer deposition (ALD) is used to deposit ultrathin layers of alumina (Al2O3) on the surface of the quartz nanopipettes enabling sub-nm tuning of the pore dimensions. Here, Al2O3 with a thickness of 8, 14 and 17 nm was deposited onto pipettes with a starting pore diameter of 75 ± 5 nm whilst a second batch had 5 and 8 nm Al2O3 deposited with a starting pore diameter of 25 ± 3 nm respectively. This highly conformal process coats both the inner and outer surfaces of pipettes and resulted in the fabrication of pore diameters as low as 7.5 nm. We show that Al2O3 modified pores do not interfere with the sensing ability of the nanopipettes and can be used for high signal-to-noise DNA detection. ALD provides a quick and efficient (batch processing) for fine-tuning nanopipettes for a broad range of applications including the detection of small biomolecules like RNA, aptamers and DNA–protein interactions at the single molecule level. [ABSTRACT FROM AUTHOR]

Wepresent metallic nanohole arrays fabricated on suspended membranesas an optofluidic substrate. Millimeter-sized suspended nanohole arrayswere fabricated using nanoimprint lithography. We demonstrate refractive-index-basedtuning of the optical spectra using a sucrose solution for the optimizationof SERS signal intensity, leading to a Raman enhancement factor of107. Furthermore, compared to dead-ended nanohole arrays,suspended nanohole arrays capable of flow-through detection increasedthe measured SERS signal intensity by 50 times. For directed transportof analytes, we present a novel methodology utilizing surface tensionto generate spontaneous flow through the nanoholes with flow ratesof 1 μL/min, obviating the need for external pumps or microfluidicinterconnects. Using this method for SERS, we obtained a 50 timeshigher signal as compared to diffusion-limited transport and coulddetect 100 pM 4-mercaptopyridine. The suspended nanohole substratespresented herein possess a uniform and reproducible geometry and showthe potential for improved analyte transport and SERS detection. [ABSTRACT FROM AUTHOR]

Metallic nanopore arrays have emerged as optofluidic platforms with multifarious sensing and analytical capabilities such as label-free surface plasmon resonance (SPR) sensing of molecular binding interactions and surface- enhanced Rasnan spectroscopy (SERS). However, directed delivery of analytes through open nanopores using traditional methods such as external electric fields or pressure gradients still remains difficult. We demonstrate that nanopore arrays have an intrinsic ability to promote flow through them via capillary flow and evaporation. This passive "nano-drain" mechanism is utilized to concentrate biomolecules on the surface of nanopores for improved detection sensitivity or create ordered nanoscale arrays of beads and liposomes. Without using any external pump or fluidic interconnects, we can concentrate and detect the presence of less than a femtomole of streptavidin in 10 μL of sample using fluorescence imaging. Liposome nanoarrays are also prepared in less than 5 mm and used to detect lipid-protein interactions. We also demonstrate label-free SPR detection of analytes using metallic nanopore arrays. This method provides a fast, simple, transportable, and small-volume platform for labeled as well as label-free plasmonic analysis while improving the detection time and sensitivity. [ABSTRACT FROM AUTHOR]

We have demonstrated metal-on-silicon thermocouples with a noticeably high Seebeck coefficient and an excellent temperature-sensing resolution. Fabrication of the thermocouples involved only simple photolithography and metal-liftoff procedures on a silicon substrate. The experimentally measured Seebeck coefficient of our thermocouple was 9.17 × 10−4 V/°K, which is 30 times larger than those reported for standard metal thin-film thermocouples and comparable to the values of alloy-based thin-film thermocouples that require sophisticated and costly fabrication processes. The temperature-voltage measurements between 20 to 80 °C were highly linear with a linearity coefficient of 1, and the experimentally demonstrated temperature-sensing resolution was 0.01 °K which could be further improved up to a theoretical limit of 0.00055 °K. Finally, we applied this approach to demonstrate a flexible metal-on-silicon thermocouple with enhanced thermal sensitivity. The outstanding performance of our thermocouple combined with an extremely thin profile, bending flexibility, and simple, highly-compatible fabrication will proliferate its use in diverse applications such as micro-/nanoscale biometrics, energy management, and nanoscale thermography. [ABSTRACT FROM AUTHOR]

The ongoing pandemic and increasing frequency of infectious disease outbreaks due to climate change, urbanization, and global human migration have put great focus on nucleic acid amplification‐based diagnostic technologies (NAAT). These methods can provide gold standard accuracy and sensitivity, and their widespread availability at the point‐of‐care is crucial for managing the spread of pathogens in human and animal populations, as well as for environmental surveillance. However, so far the reach of NAAT‐based platforms has mostly remained limited to centralized facilities in the hand of trained workers, causing great distress in times of need. In this review, the current state‐of‐the‐art research, as well as, commercial diagnostic products, is highlighted, their performances are discussed, and the role of academic‐industrial collaborations in developing the next generation of breakthrough technologies is emphasized. It is envisioned that with these collaborations, the next generation of autonomous, affordable, and mobile NAAT devices can be developed, for a broad range of targets, and for providing truly democratized access to NAAT diagnostics for the global population in the future. [ABSTRACT FROM AUTHOR]

Centralized manufacturing and global supply chains have emerged as an efficient strategy for large-scale production of goods throughout the 20th century. However, while this system of production is highly efficient, it is not resilient. The COVID-19 pandemic has seen numerous supply chains fail to adapt to sudden changes in supply and demand, including those for goods critical to the pandemic response such as personal protective equipment. Here, we consider the production of the non-woven polypropylene filtration media used in face filtering respirators (FFRs). The FFR supply chain's reliance on non-woven media sourced from large, centralized manufacturing facilities led to a supply chain failure. In this study, we present an alternative manufacturing strategy that allows us to move towards a more distributed manufacturing practice that is both scalable and robust. Specifically, we demonstrate that a fiber production technique known as centrifugal melt spinning can be implemented with modified, commercially-available cotton candy machines to produce nano- and microscale non-woven fibers. We evaluate several post processing strategies to transform the produced material into viable filtration media and then characterize these materials by measuring filtration efficiency and breathability, comparing them against equivalent materials used in commercially-available FFRs. Additionally, we demonstrate that waste plastic can be processed with this technique, enabling the development of distributed recycling strategies to address the growing plastic waste crisis. Since this method can be employed at small scales, it allows for the development of an adaptable and rapidly deployable distributed manufacturing network for non-woven materials that is financially accessible to more people than is currently possible. [ABSTRACT FROM AUTHOR]

Global shortages of N95 respirators have led to an urgent need of N95 decontamination and reuse methods that are scientifically validated and available world-wide. Although several large scale decontamination methods have been proposed (hydrogen peroxide vapor, UV-C); many of them are not applicable in remote and low-resource settings. Heat with humidity has been demonstrated as a promising decontamination approach, but care must be taken when implementing this method at a grassroots level. Here we present a simple, scalable method to provide controlled humidity and temperature for individual N95 respirators which is easily applicable in low-resource settings. N95 respirators were subjected to moist heat (>50% relative humidity, 65–80°C temperature) for over 30 minutes by placing them in a sealed container immersed in water that had been brought to a rolling boil and removed from heat, and then allowing the containers to sit for over 45 minutes. Filtration efficiency of 0.3–4.99 μm incense particles remained above 97% after 5 treatment cycles across all particle size sub-ranges. This method was then repeated at a higher ambient temperature and humidity in Mumbai, using standard utensils commonly found in South Asia. Similar temperature and humidity profiles were achieved with no degradation in filtration efficiencies after 6 cycles. Higher temperatures (>70°C) and longer treatment times (>40 minutes) were obtained by insulating the outer vessel. We also showed that the same method can be applied for the decontamination of surgical masks. This simple yet reliable method can be performed even without electricity access using any heat source to boil water, from open-flame stoves to solar heating, and provides a low-cost route for N95 decontamination globally applicable in resource-constrained settings. [ABSTRACT FROM AUTHOR]

Keywords: molecular diagnostics; nucleic acid amplification technologies; nucleic acids; point-of-cares EN molecular diagnostics nucleic acid amplification technologies nucleic acids point-of-cares 1 1 1 10/30/23 20231024 NES 231024 B Mobile Health Devices b Mobile-health platforms have the potential to provide real-time monitoring, diagnosis, and treatment options to individuals regardless of their location. Enabled by university-industry collaborations, in article 2300230, Hyuck Choo, Youngeun Kim, Shailabh Kumar, and co-workers envision a new generation of autonomous, affordable, and mobile health devices, for a broad range of targets, and providing truly democratized access to nucleic acid-based diagnostics for the global population in the future. Molecular diagnostics, nucleic acid amplification technologies, nucleic acids, point-of-cares. [Extracted from the article]

Cost-effective production of lignocellulosic biofuel requires efficient breakdown of cell walls present in plant biomass to retrieve the wall polysaccharides for fermentation. In-depth knowledge of plant cell wall composition is therefore essential for improving the fuel production process. The precise spatial three-dimensional (3D) organization of cellulose, hemicellulose, pectin and lignin within plant cell walls remains unclear to date since the microscopy techniques used so far have been limited to two-dimensional, topographic or low-resolution imaging, or required isolation or chemical extraction of the cell walls. In this paper we demonstrate that by cryo-immobilizing fresh tissue, then either cryo-sectioning or freeze-substituting and resin embedding, followed by cryo- or room temperature (RT) electron tomography, respectively, we can visualize previously unseen details of plant cell wall architecture in 3D, at macromolecular resolution (∼2 nm), and in near-native state. Qualitative and quantitative analyses showed that wall organization of cryo-immobilized samples were preserved remarkably better than conventionally prepared samples that suffer substantial extraction. Lignin-less primary cell walls were well preserved in both self-pressurized rapidly frozen (SPRF), cryo-sectioned samples as well as high-pressure frozen, freeze-substituted and resin embedded (HPF-FS-resin) samples. Lignin-rich secondary cell walls appeared featureless in HPF-FS-resin sections presumably due to poor stain penetration, but their macromolecular features could be visualized in unprecedented details in our cryo-sections. While cryo-tomography of vitreous tissue sections is currently proving to be instrumental in developing 3D models of lignin-rich secondary cell walls, here we confirm that the technically easier method of RT-tomography of HPF-FS-resin sections could be used immediately for routine study of low-lignin cell walls. As a proof of principle, we characterized the primary cell walls of a mutant (cob-6) and wild type Arabidopsis hypocotyl parenchyma cells by RT-tomography of HPF-FS-resin sections, and detected a small but significant difference in spatial organization of cellulose microfibrils in the mutant walls. [ABSTRACT FROM AUTHOR]

Matrix molecules convey biochemical and physical guiding signals to neurons in the central nervous system (CNS) and shape the trajectory of neuronal fibers that constitute neural networks. We have developed recombinant human IgMs that bind to epitopes on neural cells, with the aim of treating neurological diseases. Here we test the hypothesis that recombinant human IgMs (rHIgM) can guide neurite outgrowth of CNS neurons. Microcontact printing was employed to pattern rHIgM12 and rHIgM22, antibodies that were bioengineered to have variable regions capable of binding to neurons or oligodendrocytes, respectively. rHIgM12 promoted neuronal attachment and guided outgrowth of neurites from hippocampal neurons. Processes from spinal neurons followed grid patterns of rHIgM12 and formed a physical network. Comparison between rHIgM12 and rHIgM22 suggested the biochemistry that facilitates anchoring the neuronal surfaces is a prerequisite for the function of IgM, and spatial properties cooperate in guiding the assembly of neuronal networks [ABSTRACT FROM AUTHOR]