Spectrochemical Probing of MicroRNA Duplex Using Spontaneous Raman Spectroscopy for Biosensing Applications.

MicroRNAs are emerging as both diagnostic and therapeutic targets in different human pathologies. An accurate understanding of the structural dependency of microRNAs for their biological functions is essential for designing synthetic oligos with various base and linkage modifications that can transform into highly sensitive diagnostic devices and therapeutic molecules. In this proof-of-principle study, we have utilized label-free spontaneous Raman spectroscopy to understand the structural differences in sense and antisense microRNA-21 by hybridizing them with complementary RNA and DNA oligos. Overall, the results suggest that the changes in the Raman band at 785 cm-1 originating from the phosphodiester bond of the nucleic acid backbone, linking 5' phosphate of the nucleic acid with 3' OH of the other nucleotide, can serve as a marker to identify these structural variations. Our results support the application of Raman spectroscopy in discerning intramolecular (ssRNA and ssDNA) and intermolecular (RNA-RNA, RNA-DNA, and DNA-DNA hybrids) interactions of nucleic acids. This is potentially useful for developing biosensors to quantify microRNAs in clinical samples and to design therapeutic microRNAs with robust functionality.

A Glycemia Risk Index (GRI) of Hypoglycemia and Hyperglycemia for Continuous Glucose Monitoring Validated by Clinician Ratings.

BACKGROUND: A composite metric for the quality of glycemia from continuous glucose monitor (CGM) tracings could be useful for assisting with basic clinical interpretation of CGM data. METHODS: We assembled a data set of 14-day CGM tracings from 225 insulin-treated adults with diabetes. Using a balanced incomplete block design, 330 clinicians who were highly experienced with CGM analysis and interpretation ranked the CGM tracings from best to worst quality of glycemia. We used principal component analysis and multiple regressions to develop a model to predict the clinician ranking based on seven standard metrics in an Ambulatory Glucose Profile: very low-glucose and low-glucose hypoglycemia; very high-glucose and high-glucose hyperglycemia; time in range; mean glucose; and coefficient of variation. RESULTS: The analysis showed that clinician rankings depend on two components, one related to hypoglycemia that gives more weight to very low-glucose than to low-glucose and the other related to hyperglycemia that likewise gives greater weight to very high-glucose than to high-glucose. These two components should be calculated and displayed separately, but they can also be combined into a single Glycemia Risk Index (GRI) that corresponds closely to the clinician rankings of the overall quality of glycemia (r = 0.95). The GRI can be displayed graphically on a GRI Grid with the hypoglycemia component on the horizontal axis and the hyperglycemia component on the vertical axis. Diagonal lines divide the graph into five zones (quintiles) corresponding to the best (0th to 20th percentile) to worst (81st to 100th percentile) overall quality of glycemia. The GRI Grid enables users to track sequential changes within an individual over time and compare groups of individuals. CONCLUSION: The GRI is a single-number summary of the quality of glycemia. Its hypoglycemia and hyperglycemia components provide actionable scores and a graphical display (the GRI Grid) that can be used by clinicians and researchers to determine the glycemic effects of prescribed and investigational treatments.

The Need for Sharps Waste Disposal Guidelines for Commercial Airports.

Travelers frequently eat at an airport before their flight. Travelers with diabetes also frequently need to lance their fingertips to check a blood glucose concentration and/or inject themselves with insulin. These actions generate medical sharps waste. Bloody sharps can be a source of needlestick injuries for other travelers or waste handlers if the waste is not safely disposed of. There are currently no guidelines or standards for medical sharps waste disposal in commercial airports or similar public places. We advocate for the establishment of guidelines for medical sharps waste disposal in commercial airports. These guidelines should include four elements: (1) design of sharps disposal bins, (2) placement of sharp disposal bins, (3) publication of locations with sharps disposal bins, and (4) safety protocols for both sharps disposal and handling sharps waste. In this article, we present the background and reasons behind our recommendation for establishing guidelines for medical waste disposal in commercial airports.

The Availability of Sharps Disposal Bins: A Survey of Airports in California.

BACKGROUND: Sharps waste, especially medical sharps waste, can put those who come into contact with it at risk for injury and exposure to blood-borne pathogens. Options for self-injectors to dispose of their sharps while traveling vary greatly - from sharps containers in limited locations in some public restrooms to large kiosks centrally located to no containers at all. Currently, there is a lack of published data on sharps disposal bins in commercial airports. We surveyed commercial airports in California to assess the current state of sharps waste disposal. Many people with diabetes routinely use sharps every day for injecting medications or for self-monitoring glucose concentrations and these people, along with others who self-inject medications, must have a safe mechanism for sharps disposal when travelling by air. METHODS: A five-question survey was sent to 30 commercial airports in California. Responses were collected and then analyzed based on the following three metrics: (1) the percentage of airports that responded and indicated that they had any sharps disposal bins, (2) the percentage of airports that responded and indicated that they had sharps disposal bins in over half their restrooms, and (3) the average percentage of bathrooms that have available sharps disposal bins in airports that responded to our survey. RESULTS: Out of 30 commercial airports in California, we received survey responses from 13 airport representatives and direct email responses from 5 airport representatives. Out of 18 total responses, 11 airports (61.1%) reported that they had some form of available sharps disposal options. Out of the 13 survey responses, 6 airports (46.2%) reported that they had sharps disposal in over 50% of their restrooms. CONCLUSION: There is a lack of consistency in sharps waste disposal options among commercial airports in California. While many commercial airports in California offer sharps waste disposal options, not all commercial airports have sharps waste disposal options in all their public restrooms. There is room for improved availability of sharps disposal bins in California's commercial airports.

Label-free discrimination of tumorigenesis stages using in vitro prostate cancer bone metastasis model by Raman imaging.

Metastatic prostate cancer colonizes the bone to pave the way for bone metastasis, leading to skeletal complications associated with poor prognosis and morbidity. This study demonstrates the feasibility of Raman imaging to differentiate between cancer cells at different stages of tumorigenesis using a nanoclay-based three-dimensional (3D) bone mimetic in vitro model that mimics prostate cancer bone metastasis. A comprehensive study comparing the classification of as received prostate cancer cells in a two-dimensional (2D) model and cancer cells in a 3D bone mimetic environment was performed over various time intervals using principal component analysis (PCA). Our results showed distinctive spectral differences in Raman imaging between prostate cancer cells and the cells cultured in 3D bone mimetic scaffolds, particularly at 1002, 1261, 1444, and 1654 cm-1, which primarily contain proteins and lipids signals. Raman maps capture sub-cellular responses with the progression of tumor cells into metastasis. Raman feature extraction via cluster analysis allows for the identification of specific cellular constituents in the images. For the first time, this work demonstrates a promising potential of Raman imaging, PCA, and cluster analysis to discriminate between cancer cells at different stages of metastatic tumorigenesis.

Evaluation of immune evasion in SARS-CoV-2 Delta and Omicron variants.

Emerging SARS-CoV-2 variants with higher transmissibility and immune escape remain a persistent threat across the globe. This is evident from the recent outbreaks of the Delta (B.1.617.2) and Omicron variants. These variants have originated from different continents and spread across the globe. In this study, we explored the genomic and structural basis of these variants for their lineage defining mutations of the spike protein through computational analysis, protein modeling, and molecular dynamic (MD) simulations. We further experimentally validated the importance of these deletion mutants for their immune escape using a pseudovirus-based neutralization assay, and an antibody (4A8) that binds directly to the spike protein's NTD. Delta variant with the deletion and mutations in the NTD revealed a better rigidity and reduced flexibility as compared to the wild-type spike protein (Wuhan isolate). Furthermore, computational studies of 4A8 monoclonal antibody (mAb) revealed a reduced binding of Delta variant compared to the wild-type strain. Similarly, the MD simulation data and virus neutralization assays revealed that the Omicron also exhibits immune escape, as antigenic beta-sheets appear to be disrupted. The results of the present study demonstrate the higher possibility of immune escape and thereby achieved better fitness advantages by the Delta and Omicron variants, which warrants further demonstrations through experimental evidences. Our study, based on in-silico computational modelling, simulations, and pseudovirus-based neutralization assay, highlighted and identified the probable mechanism through which the Delta and Omicron variants are more pathogenically evolved with higher transmissibility as compared to the wild-type strain.

Cell-shape regulation of smooth muscle cell proliferation.

Vascular smooth muscle cells (SMCs) play an important role in vascular remodeling. Heterogeneity and phenotypic changes in SMCs are usually accompanied by a morphological difference, i.e., elongated/spindle-like versus spread-out or epithelioid/rhomboid cell shapes. However, it is not known whether the cell shape directly regulates SMC proliferation, and what the underlying mechanisms are. In this study, microgrooves and micropatterned matrix islands were used to engineer the cell shape and investigate the associated biophysical and biological mechanisms. Compared to spread-out SMCs on nonpatterned surfaces, SMCs on micropatterned surfaces demonstrated elongated morphology, significantly lower cell and nucleus shape indexes, less spreading, a lower proliferation rate, and a similar response (but to a lesser extent) to platelet-derived growth factor, transforming growth factor-beta, and mechanical stretching. DNA microarray profiling revealed a lower expression of neuron-derived orphan receptor-1 (NOR-1) in elongated SMCs. Knocking down NOR-1 suppressed DNA synthesis in SMCs, suggesting that NOR-1 is a mediator of cell elongation effects. Regulation of DNA synthesis in SMCs by the cell shape alone and a decrease in DNA synthesis in the case of small cell spreading area were achieved by micropatterning SMCs on matrix islands of different shapes and spreading areas. Changes in the cell shape also affected the nucleus shape, whereas variations in the cell spreading area modulated the nucleus volume, indicating a possible link between nucleus morphology (both shape and volume) and DNA synthesis. The findings of this investigation provide insight into cell shape effects on cell structure and proliferation, and have direct implications for vascular pathophysiology.

In vivo evaluation of a microneedle-based miniature syringe for intradermal drug delivery.

A microfabrication process for miniature syringes is described. The MEMS syringes consist of a silicon plate with an array of hollow out-of-plane needles and a flexible poly-dimethylsiloxane (PDMS) reservoir attached to the back of the plate. The PDMS reservoir can be filled with a drug solution or microparticle suspension which is delivered into the skin simply by the pressure of a finger pushing on the miniature syringe. The efficiency of such a syringe for delivering a suspension of microparticles into skin tissue and a radiolabelled protein (albumin) solution into live mice is reported. Such microneedle devices could be used for the intradermal delivery of vaccination agents or for the systemic delivery of highly effective drugs.

Cell-based biosensors: Recent trends, challenges and future perspectives.

Existing at the interface of biology and electronics, living cells have been in use as biorecognition elements (bioreceptors) in biosensors since the early 1970s. They are an interesting choice of bioreceptors as they allow flexibility in determining the sensing strategy, are cheaper than purified enzymes and antibodies and make the fabrication relatively simple and cost-effective. And with advances in the field of synthetic biology, microfluidics and lithography, many exciting developments have been made in the design of cell-based biosensors in the last about five years. 3D cell culture systems integrated with electrodes are now providing new insights into disease pathogenesis and physiology, while cardiomyocyte-integrated microelectrode array (MEA) technology is set to be standardized for the assessment of drug-induced cardiac toxicity. From cell microarrays for high-throughput applications to plasmonic devices for anti-microbial susceptibility testing and advent of microbial fuel cell biosensors, cell-based biosensors have evolved from being mere tools for detection of specific analytes to multi-parametric devices for real time monitoring and assessment. However, despite these advancements, challenges such as regeneration and storage life, heterogeneity in cell populations, high interference and high costs due to accessory instrumentation need to be addressed before the full potential of cell-based biosensors can be realized at a larger scale. This review summarizes results of the studies that have been conducted in the last five years toward the fabrication of cell-based biosensors for different applications with a comprehensive discussion on the challenges, future trends, and potential inputs needed for improving them.

Structural determination of Enzyme-Graphene Nanocomposite Sensor Material.

State-of-the-art ultra-sensitive blood glucose-monitoring biosensors, based on glucose oxidase (GOx) covalently linked to a single layer graphene (SLG), will be a valuable next generation diagnostic tool for personal glycemic level management. We report here our observations of sensor matrix structure obtained using a multi-physics approach towards analysis of small-angle neutron scattering (SANS) on graphene-based biosensor functionalized with GOx under different pH conditions for various hierarchical GOx assemblies within SLG. We developed a methodology to separately extract the average shape of GOx molecules within the hierarchical assemblies. The modeling is able to resolve differences in the average GOx dimer structure and shows that treatment under different pH conditions lead to differences within the GOx at the dimer contact region with SLG. The coupling of different analysis methods and modeling approaches we developed in this study provides a universal approach to obtain detailed structural quantifications, for establishing robust structure-property relationships. This is an essential step to obtain an insight into the structure and function of the GOx-SLG interface for optimizing sensor performance.

Elastic secondary flows of semidilute DNA solutions in abrupt 90 degrees microbends.

Secondary flows that are absent in Newtonian flows are found for semidilute lambda -DNA solutions in abrupt planar 90 degrees microbends at modest levels of elasticity. Flow visualization and microparticle image velocimetry experiments show that a vortex, which is present in the inner, upstream corner of the bend, grows with increasing Reynolds and Weissenberg number (9.9x10;{-7}

Intracellular MicroRNA Quantification in Intact Cells: A Novel Strategy based on Reduced Graphene Oxide Based Fluorescence Quenching.

Nanomaterials have been proposed as key components in biosensing, imaging, and drug-delivery since they offer distinctive advantages over conventional approaches. The unique chemical and physical properties of graphene make it possible to functionalize and develop protein transducers, therapeutic delivery vehicles, and microbial diagnostics. In this study we evaluate reduced graphene oxide (rGO) as a potential nanomaterial for quantification of microRNAs including their structural differentiation in vitro in solution and inside intact cells. Our results provide evidence for the potential use of graphene nanomaterials as a platform for developing devices that can be used for microRNA quantitation as biomarkers for clinical applications.

Microneedles and transdermal applications.

With the limitations of oral drug delivery and the pain and needle phobias associated with traditional injections, drug delivery research has focused on the transdermal delivery route. A formidable barrier to transdermal drug delivery is the stratum corneum, the superficial layer of the skin. In the last 10 years, microneedles were proposed as a mechanical tool to pierce through the stratum corneum, in order to create drug delivery channels without stimulating underlying pain nerves. Since then, the field of microneedles has rapidly evolved to spawn a plethora of potential transdermal applications. In this review, the authors provide an overview of the progress in microneedle research and design, and the advancements that have been made in employing this technology for transdermal applications.

Strategy for active mixing in microdevices.

We present a concept for and experimental demonstration of an active microfluidic mixer that uses microvalves to control periodic flow deviation. This active design allows the degree of mixing to be varied independently of flow rate. The mixer is compact and efficient, achieving mixing of different fluids through chaotic advection by stretching and folding the interface of the fluids.

An oral microjet vaccination system elicits antibody production in rabbits.

Noninvasive immunization technologies have the potential to revolutionize global health by providing easy-to-administer vaccines at low cost, enabling mass immunizations during pandemics. Existing technologies such as transdermal microneedles are costly, deliver drugs slowly, and cannot generate mucosal immunity, which is important for optimal immunity against pathogens. We present a needle-free microjet immunization device termed MucoJet, which is a three-dimensional microelectromechanical systems-based drug delivery technology. MucoJet is administered orally, placed adjacent to the buccal tissue within the oral cavity, and uses a self-contained gas-generating chemical reaction within its two-compartment plastic housing to produce a high-pressure liquid jet of vaccine. We show that the vaccine jet ejected from the MucoJet device is capable of penetrating the buccal mucosal layer in silico, in porcine buccal tissue ex vivo, and in rabbits in vivo. Rabbits treated with ovalbumin by MucoJet delivery have antibody titers of anti-ovalbumin immunoglobulins G and A in blood serum and buccal tissue, respectively, that are three orders of magnitude higher than rabbits receiving free ovalbumin delivered topically by a dropper in the buccal region. MucoJet has the potential to accelerate the development of noninvasive oral vaccines, given its ability to elicit antibody production that is detectable locally in the buccal tissue and systemically via the circulation.

Biomimetic technique for adhesion-based collection and separation of cells in a microfluidic channel.

A basic step in many biological assays is separating and isolating different types of cells from raw samples. To better meet these requirements in microfluidic devices for miniature biomedical analytical systems, an alternative method for separating cells has been devised by mimicking the physiological process of leukocyte recruitment to blood vessel walls: adhesive cell rolling and transient tethering. Reproducing these interactions for cells on surfaces of microstructured fluidic channels can serve to capture and concentrate cells and even to fractionate different cell types from a continuously flowing sample. To demonstrate this principle, two designs for microstructured fluidic channels were fabricated: an array of Square pillars and another with slender, Offset pillars. These structures were coated with E-selectin IgG chimera and the interactions of HL-60 and U-937 cells with these structures were characterized. With inflow of fluidic cell suspensions, the structures were able to efficiently capture and arrest cells directly from the rapid free stream flow. After capture, cells transit through the channel in three phases: cell rolling, cell tethering, and transient re-suspension in free stream flow before re-capture. Under these interactions, captured cells were enriched several hundred-fold from the original concentration. Additionally, among collected cells, the difference in flow-driven, adhesion-mediated cell transit in the Square design suggested that the two cell types could at least be partially fractionated.

Flow of DNA solutions in a microfluidic gradual contraction.

The flow of λ-DNA solutions in a gradual micro-contraction was investigated using direct measurement techniques. The effects on DNA transport in microscale flows are significant because the flow behavior is influenced by macromolecular conformations, both viscous and elastic forces dominate inertial forces at this length scale, and the fully extended length of the molecule approaches the characteristic channel length wc (L/wc ∼ 0.13). This study examines the flow of semi-dilute and entangled DNA solutions in a gradual planar micro-contraction for low Reynolds numbers (3.7 × 10(-6 )< Re < 3.1 × 10(-1)) and high Weissenberg numbers (0.4 < Wi < 446). The semi-dilute DNA solutions have modest elasticity number, El = Wi/Re = 55, and do not exhibit viscoelastic behavior. For the entangled DNA solutions, we access high elasticity numbers (7.9 × 10(3 )< El < 6.0 × 10(5)). Video microscopy and streak images of entangled DNA solution flow reveal highly elastic behavior evidenced by the presence of large, stable vortices symmetric about the centerline and upstream of the channel entrance. Micro-particle image velocimetry measurements are used to obtain high resolution, quantitative velocity measurements of the vortex growth in this micro-contraction flow. These direct measurements provide a deeper understanding of the underlying physics of macromolecular transport in microfluidic flow, which will enable the realization of enhanced designs of lab-on-a-chip systems.

Stimuli-responsive electrodes detect oxidative stress and liver injury.

A digital point-of-care biosensor for measuring reactive oxygen species is presented based on novel reactive oxygen species responsive polymer-based electrodes. The biosensor is able to detect a drug-induced liver injury by monitoring the oxidative stress in the blood.

Line-scanning particle image velocimetry: an optical approach for quantifying a wide range of blood flow speeds in live animals.

BACKGROUND: The ability to measure blood velocities is critical for studying vascular development, physiology, and pathology. A key challenge is to quantify a wide range of blood velocities in vessels deep within living specimens with concurrent diffraction-limited resolution imaging of vascular cells. Two-photon laser scanning microscopy (TPLSM) has shown tremendous promise in analyzing blood velocities hundreds of micrometers deep in animals with cellular resolution. However, current analysis of TPLSM-based data is limited to the lower range of blood velocities and is not adequate to study faster velocities in many normal or disease conditions. METHODOLOGY/PRINCIPAL FINDINGS: We developed line-scanning particle image velocimetry (LS-PIV), which used TPLSM data to quantify peak blood velocities up to 84 mm/s in live mice harboring brain arteriovenous malformation, a disease characterized by high flow. With this method, we were able to accurately detect the elevated blood velocities and exaggerated pulsatility along the abnormal vascular network in these animals. LS-PIV robustly analyzed noisy data from vessels as deep as 850 µm below the brain surface. In addition to analyzing in vivo data, we validated the accuracy of LS-PIV up to 800 mm/s using simulations with known velocity and noise parameters. CONCLUSIONS/SIGNIFICANCE: To our knowledge, these blood velocity measurements are the fastest recorded with TPLSM. Partnered with transgenic mice carrying cell-specific fluorescent reporters, LS-PIV will also enable the direct in vivo correlation of cellular, biochemical, and hemodynamic parameters in high flow vascular development and diseases such as atherogenesis, arteriogenesis, and vascular anomalies.