Use Of Probes Research Articles

Portable ultrasound devices for obstetric care in resource-constrained environments: mapping the landscape

Background The WHO’s recommendations on antenatal care underscore the need for ultrasound assessment during pregnancy. Given that maternal and perinatal mortality remains unacceptably high in underserved regions, these guidelines are imperative for achieving better outcomes. In recent years, portable ultrasound devices have become increasingly popular in resource-constrained environments due to their cost-effectiveness, useability, and adoptability in resource-constrained settings. This desk review presents the capabilities and costs of currently available portable ultrasound devices, and is meant to serve as a resource for clinicians and researchers in the imaging community. Methods A list of ideal technical features for portable ultrasound devices was developed in consultation with subject matter experts (SMEs). Features included image acquisition modes, cost, portability, compatibility, connectivity, data storage and security, and regulatory certification status. Information on each of the devices was collected from publicly available information, input from SMEs and/or discussions with company representatives. Results 14 devices were identified and included in this review. The output is meant to provide objective information on ideal technical features for available ultrasound systems to researchers and clinicians working in obstetric ultrasound in low-resource settings. No product endorsements are provided. Conclusions This desk review provides an overview of the landscape of low-cost portable ultrasound probes for use in obstetrics in resource-constrained environments, and provides a description of key capabilities and costs for each. Methods could be applied to mapping the landscape of portable ultrasound devices for other clinical applications, or may be extended to reviewing other types of healthcare technologies. Further studies are recommended to evaluate portable ultrasound devices for usability and durability in global field settings.

A Simple and Fast Optical Clearing Method for Whole-Mount Fluorescence In Situ Hybridization (FISH)Imaging.

We report a single-step optical clearing method that is compatible with RNA fluorescence in situ hybridization (FISH) imaging. We previously demonstrated microscopy imaging with immunohistochemistry and genetic reporters using a technique called lipid-preserving refractive index matching for prolonged imaging depth (LIMPID). Our protocol reliably produces high-resolution three-dimensional (3D) images with minimal aberrations using high magnification objectives, captures large field-of-view images of whole-mount tissues, and supports co-labeling with antibody and FISH probes. We also custom-designed FISH probes for quail embryos, demonstrating the ease of fabricating probes for use with less common animal models. Furthermore, we show high-quality 3D images using a conventional fluorescence microscope, without using more advanced depth sectioning instruments such as confocal or light-sheet microscopy. For broader adoption, we simplified and optimized 3D-LIMPID-FISH to minimize the barrier to entry, and we provide a detailed protocol to aid users with navigating the thick and thin of 3D microscopy.

Assembly and characterization of an optical fiber probe for use in a portable Raman spectrometer

This study describes the assembly and testing of an optical fiber Raman probe for use in a portable spectrometer using a 785 nm laser. The Raman probe was tested on edible vegetable oils (extra virgin olive, canola, sunflower, corn, and soybean), with the distal end of the probe immersed in each sample. The spectra of a dipyrone tablet and a mothball were also obtained. The silica peaks were subtracted by taking a spectrum with the probe tip immersed in water. The spectra of the samples exhibited characteristic peaks from vibrations of unsaturated fatty acids between 900 and 1800 cm−1, as well as characteristic peaks of silica from 600 to 1200 cm−1. The spectra of the samples after subtraction of the silica spectrum (probe in water) showed characteristic peaks without alterations in position or relative intensities compared without the probe. Exploratory analysis by principal component analysis was able to identify peaks of the constituent fatty acids in the oils and associate them with the oil type. A classification model based on partial least squares regression allowed for the classification of oil spectra with an accuracy of 77%. This study demonstrated the feasibility of coupling a probe to a portable Raman spectrometer with the goal of monitoring and controlling industrial processes.

Development and Optimization of Oligonucleotide Ligation Assay (OLA) Probes for Detection of HIV-1 Resistance to Dolutegravir.

The WHO currently recommends dolutegravir (DTG)-based ART for persons living with HIV infection in resource-limited-settings (RLS). To expand access to testing for HIV drug resistance (DR) to DTG in RLS, we developed probes for use in the oligonucleotide ligation assay (OLA)-Simple, a near-point of care HIV DR kit. Genotypic data from clinical trials and case reports were used to determine the mutations in HIV-1 integrase critical to identifying individuals with DTG-resistance at virologic failure of DTG-based ART. Probes to detect G118R, Q148H/K/R, N155H and R263K in HIV-1 subtypes A, B, C, D and CRF01_AE were designed using sequence alignments from the Los Alamos database and validated using 61 clinical samples of HIV-1 subtypes A, B, C, D, CRF01_AE genotyped by PacBio (n = 15) or Sanger (n = 46). Initial OLA probes failed to ligate for 16/244 (6.5%) codons (9 at G118R and 7 at Q148H/K/R). Probes revised to accommodate polymorphisms interfering with ligation at codons G118R and Q148R reduced indeterminates to 3.7% (5 at G118R and 4 at Q148H/K/R) and detected DTG-mutations with a sensitivity of 96.5% and 100% specificity. These OLA DTG resistance probes appear highly sensitive and specific across HIV-1 subtypes common in RLS with high burden of HIV infection.

Co-factor prosthesis facilitates biosynthesis of azido-pseudaminic acid probes for use as glycosyltransferase reporters.

Truncated thioester N,S-diacetylcysteamine (SNAc) was utilised as a co-factor mimic for PseH, an acetyl-coA dependent aminoglycoside N-acetyltransferase, in the biosynthesis of the bacterial sugar, pseudaminic acid. Additionally, an azido-SNAc analogue was used to smuggle N7-azide functionality into the pseudaminic acid backbone, facilitating its use as a reporter of pseudaminyltransferase activity.

A Feasibility Study in Virtual Assessment Procedures of a Sentence-Writing Probe for Use With Intermediate-Grade Students

This article reports on the development and initial feasibility of virtual assessment procedures for a sentence-writing probe for remote instructional purposes with intermediate-grade students. The study included a sample of 15 intermediate-grade children. The sentence-writing probe was administered through video conferencing software, an innovation of the times, across three sessions separated by 2 weeks. Scores derived from sentence probes included total number of words, a sentence accuracy score, and a word accuracy score, which were compared across time points. Results indicated no statistically significant differences across time points for the entire sample for all measures except the total number of words at Time 2. Measures obtained from the sentence-writing probe were significantly correlated with standardized measures of oral language. Findings from this study support the proof of concept that virtual assessment procedures can be used to assess sentence-level writing in intermediate-grade students. Future directions are provided regarding the utility of remote instruction for assessment purposes, the types of scores derived from measures, and future plans to scale up the assessment for use in research studies and as a curriculum-based evaluation tool.

Characterization of an OCT probe for use in the diagnosis of precancerous lesions of the cervix

The development of an auxiliary diagnostic tool (OCT probe) for application in the assessment of cervical cancer is being carried out and may have an impact on the diagnostic process and, consequently, on the reduction of the incidence of female mortality from cervical cancer, by allowing a more accurate assessment of the extent of the lesion and by enabling the expansion of this assessment within the endocervical canal. In addition to the scientific result, the use of available equipment will boost the quality of clinical care currently available for diagnosis. Combining technical development with a precise methodology and clinical application, the probe developed will have a scientific impact of socio-economic relevance for society. As it is an optical measurement, it is necessary to evaluate the optical characteristics of the developed probes and the choice of one of them was made taking into account the measurements carried out and the application of metrological concepts.

Which Small Molecule? Selecting Chemical Probes for Use in Cancer Research and Target Validation.

Validation of biological targets and pathways will be aided by a shared understanding of the criteria of potency, selectivity, and target engagement associated with small-molecule reagents ("chemical probes") that enable that work. Interdisciplinary collaboration between cancer biologists, medicinal chemists, and chemical biologists and the awareness of available resources will reduce misleading data generation and interpretation, strengthen data robustness, and improve productivity in academic and industrial research.

Fluorescent Materials Containing Polycyclic Aromatic Compounds: synthesis, Fluorimetric Detection of Nitroaromatic Compounds and Color Properties

Schiff bases with pyrene, anthracene or naphthalene groups can act as simple, sensitive, and selective sensors for the detection of trace explosives. We have prepared three new types of Schiff bases with fluorescent properties as fluorescent probes for use in the fluorescence detection of explosives. The detection properties of the synthesized compounds of photophysical and fluorescent explosives were investigated. Spectroscopic methods were used for the structural characterization of the compounds. Within the scope of the study, compounds (A, B and C) were used as fluorescent probes in the detection of some explosives and the data obtained were recorded. Instead of the quenching effect expected by the explosives on the emissions of the compounds, it was observed in some experiments that the emission intensity due to aggregation increased. In addition, the color measurements (CIE standards) and Color temperature (CCT) of the compounds were calculated.

Biosynthesis of uniform fluorescent-stable telluride quantum dots in Escherichia coli and its detection of Fe3+ in water

Quantum dots (QDs) containing zinc (Zn) and tellurium (Te) have low toxicity and excellent optoelectronic properties, which make them ideal fluorescent probes for use in environmental monitoring. However, their size/shape distribution synthesized by existing methods is not as good as that of other nanoparticles, thus limiting their application. Exploring whether this kind of QD can be biosynthesized and whether it can act as a nanoprobe are favorable attempts to expand the synthesis method and the application of QDs. Telluride QDs were biosynthesized in Escherichia coli cells. The nanoparticles were characterized by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray spectroscopy (EDX), and inductively coupled plasma-atomic emission spectrometry (ICP‒AES), indicating that they were Zn3STe2 QDs. The QDs were monodispersed, spherical and fluorescently stable, with a uniform particle size of 3.05 ± 0.48 nm. The biosynthesis conditions of the QDs, including substrate concentrations and their process time, were optimized respectively. It was verified that the cysE and cysK genes were involved in the biosynthesis of telluride QDs. The biosynthesis ability of the QDs was improved by knocking out the tehB gene and overexpressing the pckA gene. Escherichia coli BW25113 cells that synthesized Zn3STe2 QDs were used as environmentally friendly fluorescent bioprobes to specifically select and quantitatively detect Fe3+ in water with a low limit of detection (2.62 μM). The fluorescent cells were also photobleach resistant and had good fluorescence stability. This study expands on the synthesis method of telluride QDs and the application of fluorescent probes.

A lectin from Crenomytilus grayanus as a probe for the detection of widespread cancerous and metastatic cells.

A novel Gal-binding lectin from mussels (Crenomytilus grayanus, CGL) with six binding sites in its the dimeric structure has been previously shown to have antifungal, anticancer and antibacterial activities. In this study, a glycan array was used to confirm that CGL recognizes a range of non-reducing end α- or β-linked Gal glycans on normal cells but not sialic acid-capped glycans. This finding suggests that CGL has potential in the tumor detection due to the hyper-sialylation present in cell surface glycans from cancer cells. To evaluate the feasibility of this possibility, we labeled CGL with biotin and then mixed it with streptavidin-HRP to create a CGL-biotin-SP complex as a probe for use in enzyme-linked lectin assays (ELLA). CGL-biotin-SP successfully distinguished not only HeLa cells and de-sialylated HeLa cells that mimic normal cell surface glycans but also lung and breast cancer cells with different metastatic abilities. This work provides the insights into a new Gal-binding lectin by establishing its specificity and also demonstrates practical applications in cancer diagnosis greater than other reported lectins.

NanoB2 to monitor interactions of ligands with membrane proteins by combining nanobodies and NanoBRET

The therapeutic potential of ligands targeting disease-associated membrane proteins is predicted by ligand-receptor binding constants, which can be determined using NanoLuciferase (NanoLuc)-based bioluminescence resonance energy transfer (NanoBRET) methods. However, the broad applicability of these methods is hampered by the restricted availability of fluorescent probes. We describe the use of antibody fragments, like nanobodies, as universal building blocks for fluorescent probes for use in NanoBRET. Our nanobody-NanoBRET (NanoB2) workflow starts with the generation of NanoLuc-tagged receptors and fluorescent nanobodies, enabling homogeneous, real-time monitoring of nanobody-receptor binding. Moreover, NanoB2 facilitates the assessment of receptor binding of unlabeled ligands in competition binding experiments. The broad significance is illustrated by the successful application of NanoB2 to different drug targets (e.g., multiple G protein-coupled receptors [GPCRs] and a receptor tyrosine kinase [RTK]) at distinct therapeutically relevant binding sites (i.e., extracellular and intracellular).

Fabrication of P and N Co-Doped Carbon Dots for Fe3+ Detection in Serum and Lysosomal Tracking in Living Cells.

Doping with heteroatoms allows the retention of the general characteristics of carbon dots while allowing their physicochemical and photochemical properties to be effectively modulated. In this work, we report the preparation of ultrastable P and N co-doped carbon dots (PNCDs) that can be used for the highly selective detection of Fe3+ and the tracking of lysosomes in living cells. Fluorescent PNCDs were facilely prepared via a hydrothermal treatment of ethylenediamine and phytic acid, and they exhibited a high quantum yield of 22.0%. The strong coordination interaction between the phosphorus groups of PNCDs and Fe3+ rendered them efficient probes for use in selective Fe3+ detection, with a detection limit of 0.39 μM, and we demonstrated their practicability by accurately detecting the Fe3+ contents in bio-samples. At the same time, PNCDs exhibited high lysosomal location specificity in different cell lines due to surface lipophilic amino groups, and real-time tracking of the lysosome morphology in HeLa cells was achieved. The present work suggests that the fabrication of heteroatom-doped CDs might be an effective strategy to provide promising tools for cytology, such as organelle tracking.

The Cyanobacterial "Nutraceutical" Phycocyanobilin Inhibits Cysteine Protease Legumain.

The blue biliprotein phycocyanin, produced by photo-autotrophic cyanobacteria including spirulina (Arthrospira) and marketed as a natural food supplement or "nutraceutical," is reported to have anti-inflammatory, antioxidant, immunomodulatory, and anticancer activity. These diverse biological activities have been specifically attributed to the phycocyanin chromophore, phycocyanobilin (PCB). However, the mechanism of action of PCB and the molecular targets responsible for the beneficial properties of PCB are not well understood. We have developed a procedure to rapidly cleave the PCB pigment from phycocyanin by ethanolysis and then characterized it as an electrophilic natural product that interacts covalently with thiol nucleophiles but lacks any appreciable cytotoxicity or antibacterial activity against common pathogens and gut microbes. We then designed alkyne-bearing PCB probes for use in chemical proteomics target deconvolution studies. Target identification and validation revealed the cysteine protease legumain (also known as asparaginyl endopeptidase, AEP) to be a target of PCB. Inhibition of this target may account for PCB's diverse reported biological activities.

A Dual-Polarization Scattering Probe for Modulated Scatterer Technique Measurements

A scattering probe for use in the modulated scatterer technique (MST) measurements was proposed. The proposed probe has dual-polarization capability and a high modulation depth (MD) for both polarizations. The high MD values are made possible by loading shorted transmission lines (STLs) at the center of dipoles, such that the integration of the dipole currents vanishes, resulting in an electrically invisible state for broadside observations. For the actual implementation of the dual-polarization MST probes, the scattering geometry on an FR-4 substrate was considered and the effects of the substrates, particularly in the invisible states, were studied. The dual-polarization scattering probes (DPSPs) were implemented on FR-4 substrates using 4 PIN diode switches, low-frequency blocking capacitors, and biasing structures to provide bias voltages to the PIN diode switches. The biasing structures were implemented using inductors and resistive wires. The locations of the blocking capacitors were offset from the ends of the dipoles to compensate for the nonideal characteristics of the PIN diodes and other parts. The performance of the implemented DPSPs was measured and demonstrated to have high MDs for both polarizations over a wide bandwidth indicating that the proposed probe may increase the sensitivity of the MST system.

On the Fabrication and Characterization of Polymer-Based Waveguide Probes for Use in Future Optical Cochlear Implants.

Improved hearing restoration by cochlear implants (CI) is expected by optical cochlear implants (oCI) exciting optogenetically modified spiral ganglion neurons (SGNs) via an optical pulse generated outside the cochlea. The pulse is guided to the SGNs inside the cochlea via flexible polymer-based waveguide probes. The fabrication of these waveguide probes is realized by using 6" wafer-level micromachining processes, including lithography processes such as spin-coating cladding layers and a waveguide layer in between and etch processes for structuring the waveguide layer. Further adhesion layers and metal layers for laser diode (LD) bonding and light-outcoupling structures are also integrated in this waveguide process flow. Optical microscope and SEM images revealed that the majority of the waveguides are sufficiently smooth to guide light with low intensity loss. By coupling light into the waveguides and detecting the outcoupled light from the waveguide, we distinguished intensity losses caused by bending the waveguide and outcoupling. The probes were used in first modules called single-beam guides (SBGs) based on a waveguide probe, a ball lens and an LD. Finally, these SBGs were tested in animal models for proof-of-concept implantation experiments.

Nonblinking Core–Multishell InP/ZnSe/ZnS Quantum Dot Bioconjugates for Super-resolution Imaging

Colloidal quantum dots (QDs) are vital fluorescent probes with several optical features superior to those found in organic dyes for microscopy imaging. However, the emission blinking behavior of a single QD is an intrinsic drawback for stimulated emission depletion microscopy (STED) or structured illumination microscopy techniques. Herein, we present a rational strategy for the synthesis of a type of deterministic, environmentally friendly, small nonblinking core–multishell InP/ZnSe/ZnS QD using a hydrofluoric acid (HF) etching passivation. The strategy includes four steps: synthesis of the InP core, synthesis of oil-phase core–multishell InP/ZnSe/ZnS QDs using hydrogen fluoride and trioctylphosphine etching passivation, promotion of the water solubility of QDs modified by 3-mercaptopropionic acid (MPA), and enhanced biotargeting of core–multishell InP/ZnSe/ZnS QDs by surface coupling technology. The suppressed blinking mechanism was primarily attributed to surface wrapping shells and HF etching passivation of surface dangling bonds, which reduced surface nonradiative recombination. Nonblinking QDs exhibit high fluorescence efficiency (∼90%), good photostability (>20 min), a large Stokes shift (>135 nm), biocompatibility of the cell viability (>90%), and high targeting. Furthermore, super-resolution multifocal structured illumination microscopy imaging of subcellular structures labeled using these QDs confirmed a resolution improvement of greater than 2.6-fold compared to wide-field microscopy. The results indicate that the nonblinking QDs can function as excellent probes for use in the long-term super-resolution visualization of subcellular dynamics.

Micro-Sized pH Sensors Based on Scanning Electrochemical Probe Microscopy.

Monitoring pH changes at the micro/nano scale is essential to gain a fundamental understanding of surface processes. Detection of local pH changes at the electrode/electrolyte interface can be achieved through the use of micro-/nano-sized pH sensors. When combined with scanning electrochemical microscopy (SECM), these sensors can provide measurements with high spatial resolution. This article reviews the state-of-the-art design and fabrication of micro-/nano-sized pH sensors, as well as their applications based on SECM. Considerations for selecting sensing probes for use in biological studies, corrosion science, in energy applications, and for environmental research are examined. Different types of pH sensitive probes are summarized and compared. Finally, future trends and emerging applications of micro-/nano-sized pH sensors are discussed.

Development of an anisokinetic particle sampling probe for use in a gas turbine engine compressor

Sand and dust particle ingestion is an inevitability for aircraft operating in arid environments. For conventional takeoff and landing aircraft, significant dust can be ingested into the gas turbine powerplant. Helicopters and vertical takeoff and landing (VTOL) aircraft are at especially high risk due to their tendency to blow significant debris into the air during takeoff and landing operations. The present study highlights the development of an anisokinetic particle sampling probe for use in aircraft engines to obtain real-time measurement of ingested particles often present in these harsh environments. Offtake of particles during engine operation in dusty conditions will provide researchers with an improved understanding of particle breakage tendency and component erosion susceptibility. Three foundational studies were conducted to establish a baseline understanding of probe performance: an aerodynamic study, a particle tracking study, and a particle sampling study. These studies were performed using the Free Jet rig at the Advanced Propulsion and Power Laboratory at Virginia Tech. Particles as large as 1.3 mm were sampled at Mach numbers where M = (0.25, 0.70) and yaw angles ranging from 0° to 45° relative to freestream, conditions not previously investigated. Results indicate that the probe operates sub-isokinetically throughout the full range of test conditions and that probe aerodynamic capture efficiency is inversely proportional to both Mach number and yaw angle. However, this efficiency limitation does not notably influence the sampling probe’s ability to capture the test dust of interest. While the presence of the probe in the flow does result in an airflow velocity reduction of up to 55%, due to their relatively large Stokes numbers the particles of interest only experience a decrease of roughly 5%. These results indicate that this probe is capable of providing researchers with valuable particle size and shape information through effective particle sampling at particle sizes (100 μm ≤ dp ≤ 1,300 μm) and speeds (M ≥ 0.25) not previously investigated.

Mirau-based line-field confocal optical coherence tomography for three-dimensional high-resolution skin imaging.

SignificanceLine-field confocal optical coherence tomography (LC-OCT) is a recently introduced high-resolution imaging modality based on a combination of low-coherence optical interferometry and reflectance confocal optical microscopy with line illumination and line detection. Capable of producing three-dimensional (3D) images of the skin with cellular resolution, in vivo, LC-OCT has been mainly applied in dermatology and dermo-cosmetology. The LC-OCT devices capable of acquiring 3D images reported so far are based on a Linnik interferometer using two identical microscope objectives. In this configuration, LC-OCT cannot be designed to be a very compact and light device, and the image acquisition speed is limited.AimThe objective of this work was to develop a more compact and lighter LC-OCT device that is capable of acquiring images faster without significant degradation of the resolution and with optimized detection sensitivity.ApproachWe developed an LC-OCT device based on a Mirau interferometer using a single objective. Dynamic adjustment of the camera frequency during the depth scan is implemented, using a faster camera and a more powerful light source. The reflectivity of the beam-splitter in the Mirau interferometer was optimized to maximize the detection sensitivity. A galvanometer scanner was incorporated into the device for scanning the illumination line laterally. A stack of adjacent B-scans, constituting a 3D image, can thus be acquired.ResultsThe device is able to acquire and display B-scans at 17 fps. 3D images with a quasi-isotropic resolution of (1.3, 1.9, and in the , and directions, respectively) over a field of () can be obtained. 3D imaging of human skin at cellular resolution, in vivo, is reported.ConclusionsThe acquisition rate of the B-scans, at 17 fps, is unprecedented in LC-OCT. Compared with the conventional LC-OCT devices based on a Linnik interferometer, the reported Mirau-based LC-OCT device can acquire B-scans times faster. With potential advantages in terms of compactness and weight, a Mirau-based device could easily be integrated into a smaller and lighter handheld probe for use by dermatologists in their daily medical practice.