Conventional Probe Research Articles

Metabolic precision labeling enables selective probing of O-linked N-acetylgalactosamine glycosylation

Protein glycosylation events that happen early in the secretory pathway are often dysregulated during tumorigenesis. These events can be probed, in principle, by monosaccharides with bioorthogonal tags that would ideally be specific for distinct glycan subtypes. However, metabolic interconversion into other monosaccharides drastically reduces such specificity in the living cell. Here, we use a structure-based design process to develop the monosaccharide probe N-(S)-azidopropionylgalactosamine (GalNAzMe) that is specific for cancer-relevant Ser/Thr(O)-linked N-acetylgalactosamine (GalNAc) glycosylation. By virtue of a branched N-acylamide side chain, GalNAzMe is not interconverted by epimerization to the corresponding N-acetylglucosamine analog by the epimerase N-acetylgalactosamine-4-epimerase (GALE) like conventional GalNAc-based probes. GalNAzMe enters O-GalNAc glycosylation but does not enter other major cell surface glycan types including Asn(N)-linked glycans. We transfect cells with the engineered pyrophosphorylase mut-AGX1 to biosynthesize the nucleotide-sugar donor uridine diphosphate (UDP)-GalNAzMe from a sugar-1-phosphate precursor. Tagged with a bioorthogonal azide group, GalNAzMe serves as an O-glycan-specific reporter in superresolution microscopy, chemical glycoproteomics, a genome-wide CRISPR-knockout (CRISPR-KO) screen, and imaging of intestinal organoids. Additional ectopic expression of an engineered glycosyltransferase, "bump-and-hole" (BH)-GalNAc-T2, boosts labeling in a programmable fashion by increasing incorporation of GalNAzMe into the cell surface glycoproteome. Alleviating the need for GALE-KO cells in metabolic labeling experiments, GalNAzMe is a precision tool that allows a detailed view into the biology of a major type of cancer-relevant protein glycosylation.

New Screening Method For Cervical Cancer- Polar Probe

Objective: Although extensive screening methods had been developed, cervical cancer remains to be an essential health problem. Early detection and administration of appropriate therapy is still a lifesaving procedure, especially for cervical cancer. The most common screening method for cervical cancer is still the cervical cytology (Pap-test). We aim to find out the advantages and disadvantages of a recently developed method, which is called as Polar Probe.
 Methods: Two different approaches had been used (conventional Pap test and Polar Probe), and 1438 patients were included in the study. Of these, 819 had been screened with Polar Probe. All eligible patients were firstly screened using Polar Probe and then using the Pap test. Each patient with an abnormal Polar Probe result was referred to colposcopy room, where she was re-evaluated using colposcopy.
 Results: The rate of abnormal smear result was 1.04%, and the corresponding percentage was calculated as 0.62% in LSIL, 0.34% in ASCUS, and 0.069% in HSIL. A total of 819 patients underwent Polar Probe, and the results were abnormal in 261 patients and normal in 558 patients. Abnormality rate was 1% in Pap test and 31.9% in Polar Probe. Although the positive predictive value was 27% for Polar Probe test and 16% for Pap test, as the colposcopy was indicated only for the patients with abnormal results in Polar Probe. The need for colposcopy dramatically increased with the use of Polar Probe.
 Conclusion: Use of Polar Probe alone was not found to be cost effective. Combination with other methods of screening would decrease the cost of the process.

Nanoscale Charge Accumulation and Its Effect on Carrier Dynamics in Tri-cation Perovskite Structures.

Nanoscale investigations by scanning probe microscopy have provided major contributions to the rapid development of organic–inorganic halide perovskites (OIHP) as optoelectronic devices. Further improvement of device level properties requires a deeper understanding of the performance-limiting mechanisms such as ion migration, phase segregation, and their effects on charge extraction both at the nano- and macroscale. Here, we have studied the dynamic electrical response of Cs0.05(FA0.83MA0.17)0.95PbI3–xBrx perovskite structures by employing conventional and microsecond time-resolved open-loop Kelvin probe force microscopy (KPFM). Our results indicate strong negative charge carrier trapping upon illumination and very slow (>1 s) relaxation of charges at the grain boundaries. The fast electronic recombination and transport dynamics on the microsecond scale probed by time-resolved open-loop KPFM show diffusion of charge carriers toward grain boundaries and indicate locally higher recombination rates because of intrinsic compositional heterogeneity. The nanoscale electrostatic effects revealed are summarized in a collective model for mixed-halide CsFAMA. Results on multilayer solar cell structures draw direct relations between nanoscale ionic transport, charge accumulation, recombination properties, and the final device performance. Our findings extend the current understanding of complex charge carrier dynamics in stable multication OIHP structures.

Two-sensor droplet-capable conductivity probe for measurement in liquid dispersed flows

In churn to annular transition, the liquid could exist as a dispersed phase (droplets). But the conventional probe is not able to distinguish the dispersed liquid phase from the gas phase due to electrode design. To extend the measurement capability of the conductivity probe, the Two-Sensor Droplet-Capable Conductivity Probe (DCCP-2) is developed, which incorporates one more sensor to distinguish the dispersed liquid phase from the gas phase and the continuous liquid phase. This paper presents the design of DCCP-2, such as the circuit design, signal processing, and probe manufacturing process. Its capability in measuring liquid-dispersed flow is demonstrated by experiments in churn to annular transition conditions. Also, it still preserves the capability of measuring bubbly flow, which is demonstrated through benchmark experiments with the conventional probe. Therefore, the DCCP-2 serves as a reliable measurement instrument covering a wide range of two-phase flow regimes from bubbly flow to annular flow.

Nonspectroscopic Migratory Cell Monitoring Method Using Retroreflective Janus Microparticles.

This study aims to suggest a simple migratory cell monitoring method in the Transwell system by utilizing retroreflective Janus microparticles (RJPs) as an optical probe. The RJP could be internalized on cells without compromising the cell viability and can be registered as bright spots within the cell body by inducing retroreflection from nonspectroscopic light sources. Conventional optical probes (e.g., fluorophores, chromogens, and nanoparticles) have been extensively studied and applied across diverse platforms (e.g., Boyden chamber, wound closing, and microfluidic chips) for understanding in vitro kinetic cell behavior. However, the complexities of running such platforms and setting up analytical instruments are limiting. In this regard, we aimed to demonstrate a modified Transwell migration assay by introducing the retroreflection principle to the cell quantification procedures that ensure a simplified optical setup, assure easy signal acquisition, and are compatible with conventional platforms. To demonstrate retroreflection as a signaling principle, a half-metal-coated silica particle that can induce interior retroreflection was synthesized. Because the RJPs can concentrate incident light and reflect it back to the light source, retroreflection was distinctively recognizable and enabled sensitive visualization. To verify the applicability of the developed migration assay, cell quantification during the incremental progress of macrophage migration, and cell quantification under gradients of chemoattractant monocyte protein-1, was accomplished by obtaining phagocytosed RJP-mediated retroreflection signals. Considering that conventional assays are designed as endpoint measurements, we anticipate the proposed retroreflection-based cell quantification technique to be a promising solution, bypassing current limitations.

Hierarchical MnS@MoS2 architectures on tea bag filter paper for flexible, sensitive, and selective non-enzymatic hydrogen peroxide sensors

We report here the rational development of MnO2 nanorods coated tea bag filter paper (TBFP) as a self-standing, bendable, and disposable electrochemical probe for the sensitive and selective H2O2 detection and addresses their challenges in H2O2 sensing via the replacement of ‘O’ with ‘S’ in the form of MnS microcubes and its core@shell architecture with MoS2. The as-configured MnS@MoS2/TBFP overwhelms the constrains of conventional electrochemical probes including time and cost consumed electrode surface renewability and catalyst loading progression, and the practice of an insulating binder. The hierarchical open porous architectures of MoS2-shell favour the diffusion of H2O2 into the core-MnS microcubes, facilitating an analyte utilization efficacy at both the core and shell architectures. The impacts of core@shell morphological features, replacement of ‘O’ with ‘S’, surface defects, and lattice distribution of MnS@MoS2 toward non-enzymatic H2O2 sensing performances are elucidated using variant electrochemical techniques. With the synergism of uniformly implanted and exposed metallic active sites, efficient electron transfer rate, and high analyte utilization efficiency, MnS@MoS2/TBFP exposes the low detection limit (120 nM), excellent sensitivity (650 μA mM−1 cm−2), and wide linear range (500 nM-5 mM) on H2O2 detection. Furthermore, the scrutinized non-enzymatic H2O2 detection concerts of MnS/MoS2/TBFP are selective, decisive, repeatable, and stable, constructing the excellent recovery rates in human urine sample analyses. Thus, the collective benefits of free-standing, flexible, binder-less, re-functional, and cost-efficient MnS@MoS2/TBFP probe actualize the evolution of affordable and high performance H2O2 sensors.

An Optimized NMR Stripline for Sensitive Supercritical Fluid Chromatography-Nuclear Magnetic Resonance of Microliter Sample Volumes

To optimize sensitivity, there has been an increasing interest in the miniaturization of NMR detectors. In our lab, a stripline NMR detector has been developed, which provides high resolution and is scalable to a large range of sample volumes. These features make it an ideal detector for hyphenated techniques. In this manuscript, we demonstrate a stripline probe, which is designed for combining supercritical fluid chromatography (SFC) experiments with NMR. It features a novel stripline chip, designed to reduce the signal from the contact pads, which results in an improved lineshape. An external lock circuit provides stability over time to perform signal averaging or multidimensional experiments. As proof of concept, we demonstrate the SFC-NMR technique with this stripline probe using a mixture of cholesterol and cholestanol, which is relevant for studying cerebrotendinous xanthomatosis. Additionally, this probe makes it possible to record high-resolution spectra of samples with a high spin density. This means that it is possible to directly observe shifts due to the nuclear demagnetizing field in the “homomolecular” case, which is challenging using conventional probes due to broadening effects from radiation damping.

Next generation miRNA inhibition using short anti-seed PNAs encapsulated in PLGA nanoparticles

Selective inhibition of microRNAs (miRNAs) offers a new avenue for cancer therapeutics. While most of the current anti-miRNA (antimiR) reagents target full length miRNAs, here we investigate novel nanoparticle-delivered short PNA probes containing cationic domains targeting the seed region of the miRNA for effective antimiR therapy. For proof of concept, we tested PNAs targeting miRNA-155 and employed poly(lactic-co-glycolic acid) (PLGA)-based nanoparticle formulation for delivery. A comprehensive evaluation of PLGA nanoparticles (NPs) containing short PNA probes showed significantly superior loading, release profile, and uniform size distribution, compared to conventional non-cationic PNA probes. Confocal microscopy and flow cytometry analyses showed efficient transfection efficiency and uniform distribution of PLGA NPs containing short PNA probes in the cytoplasm. Functional analysis also confirmed efficient miRNA-155 inhibition including an effect on its downstream target proteins. Further, reduced tumor growth was observed after systemic delivery of PLGA nanoparticles containing short PNA probes in vivo in a xenograft mouse model following inhibition of miR-155. There was no evidence of acute or chronic toxicity associated with systemic delivery of PLGA NPs containing short PNA probes in the mice. Overall, in this paper we present a novel antimiR strategy based on PLGA nanoparticle delivered short PNA probes for potential cancer therapy.

Probing short and long‐range interactions in native collagen inside the bone matrix by BioSolids CryoProbe

Solid-state nuclear magnetic resonance is a promising technique to probe bone mineralization and interaction of collagen protein in the native state. However, many of the developments are hampered due to the low sensitivity of the technique. In this article, we report solid-state nuclear magnetic resonance (NMR) experiments using the newly developed BioSolids CryoProbe™ to access its applicability for elucidating the atomic-level structural details of collagen protein in native state inside the bone. We report here approximately a fourfold sensitivity enhancement in the natural abundance 13 C spectrum compared with the room temperature conventional solid-state NMR probe. With the advantage of sensitivity enhancement, we have been able to perform natural abundance 15 N cross-polarization magic angle spinning (CPMAS) and two-dimensional (2D) 1 H-13 C heteronuclear correlation (HETCOR) experiments of native collagen within a reasonable timeframe. Due to high sensitivity, 2D 1 H/13 C HETCOR experiments have helped in detecting several short and long-range interactions of native collagen assembly, thus significantly expanding the scope of the method to such challenging biomaterials.

A Miniature pH Probe Using Functional Microfiber Bragg Grating

Operando and precisely probing aqueous pH is fundamentally demanded, both in chemical and biological areas. Conventional pH probes, subjected to the larger size, are probably unfit for application in some extreme scenarios, such as a trace amount of samples. In this paper, we have further developed the pH sensor that leverages the microfiber Bragg grating with an ultra-compact size down to an order of magnitude of 10−14 m3. Using the electrostatic self-assembly layer-by-layer technique, the functional film consisting of sodium alginate, which harnesses a pH-dependent hygroscopicity, is immobilized on the fiber surface. Consequently, the alteration of aqueous pH could be quantitatively indicated by the wavelength shift of the grating resonance via the refractive index variation of the sensing film due to the water absorption or expulsion. The grating reflections involving fundamental mode and higher order mode exhibit the sensitivities of −72 pm/pH and −265 pm/pH, respectively. In addition, temperature compensation can be facilitated by the recording of the two reflections simultaneously. Furthermore, the modeling and simulation results predict the pivotal parameters of the configuration in sensitivity enhancement. The proposed proof-of-concept enriches the toolbox of pH sensor for catering to the need of detection in some extremely small spaces—for example, the living cells or the bio-tissues.

Improved Signal Detection Sensitivity for High Resolution Imaging in Scanning Acoustic Tomography

Abstract Scanning acoustic tomography (SAT) is widely used to detect defects such as voids and delamination in electronic devices. In this article, the authors explain how they improved the spatial resolution and detection sensitivity of SAT by switching from a conventional piezoelectric probe to a capacitive micromachined ultrasound transducer (CMUT) and by using pulse compression signal processing. They also present examples showing how the improvement makes it possible to detect very small defects in multilayer stacks and BGA packages whether in through-transmission or reflection imaging mode.

Triple Band Slotted Patch Antenna with a Notch for Wi-MAX Communications

A conventional probe fed square patch antenna with a triangular notch & a rectangular slot with perturbation is designed and simulated for triple band operation for applications in communication systems like Wi-MAX systems is presented. The antenna is designed on the glass epoxy FR4 substrate. With the fixed feed point location, the notch angle is varied from 1800 to 1400 resulting in single and dual resonance behavior of patch antenna. With the notch angle from 1800 to 1650, antenna resonates at a single frequency but on further reduction of notch angle from 1650 to 1400, dual resonance behavior is noticed with improved bandwidth. The optimum performance is obtained for a notch angle of 1500. The maximum radiation efficiency of ⁓ 40% is obtained. Further, a rectangular slot with perturbation at shorter edges give rise to additional resonant frequency. The other performance parameters of antenna are analyzed by varying notch angle and its position.

Aggregation Enhanced Responsiveness of Rationally Designed Probes to Hydrogen Sulfide for Targeted Cancer Imaging.

Activatable molecular probes hold great promise for targeted cancer imaging. However, the hydrophobic nature of most conventional probes makes them generate precipitated agglomerate in aqueous media, thereby annihilating their responsiveness to analytes and precluding their practical applications for bioimaging. This study reports the development of two small molecular probes with unprecedented aggregation enhanced responsiveness to H2S for in vivo imaging of H2S-rich cancers. The subtle modulation of the equilibrium between hydrophilicity and lipophilicity by N-methylpyridinium endows these designed probes with the capability of spontaneously self-assembling into nanoprobes under physiological conditions. Such probes in an aggregated state, rather than a molecular dissolved state, show NIR fluorescence light up and photoacoustic signals turn on upon H2S specific activation, allowing in vivo visualization and differentiation of cancers based on differences in H2S content. Thus, our study presents an effective design strategy which should pave the way to molecular design of optimized probes for precision cancer diagnostics.

Graphene/PbS quantum dot hybrid structure for application in near-infrared photodetectors

A graphene-PbS quantum dot (QD) composite for application in high-performance near-infrared (NIR) photodetectors (PDs) is proposed in this study. A single-layer graphene flake and oleic acid-capped PbS QD composite is fabricated through the conventional sonication process, in hexane solution. Field emission scanning electron microscopy images of the graphene-PbS QD composite dispersed on a glass substrate confirm that the composite contains both aggregated graphene flakes and single-layer graphene with wrinkles; Transmission electron microscopy images reveal close packing with uniform size. The increased absorbance and quenched photoluminescence intensity of the graphene-PbS QD composite supports enhanced photoinduced charge transfer between graphene and the PbS QDs. Moreover, the specific Raman mode of the PbS QDs, embedded in the spectrum, is enhanced by combination with graphene, which can be interpreted by SERS as relevant to the photoinduced charge transfer between the Pbs QDs and graphene. For device application, a PD structure comprised by graphene-PbS QDs is fabricated. The photocurrent of the PD is measured using a conventional probe station with a 980-nm NIR laser diode. In the fabricated PD comprising graphene-PbS QDs, five-times higher photocurrent, 22% faster rise time, and 47% faster decay time are observed, compared to that comprising PbS QDs alone. This establishes the potential of the graphene-PbS QD composite for application in ultrathin, flexible, high-performance NIR PDs.

A Bioresponsive Near-Infrared Fluorescent Probe for Facile and Persistent Live-Cell Tracking.

Molecular imaging significantly transforms the field of biomedical science and facilitates the visualization, characterization, and quantification of biologic processes. However, it is still challenging to monitor cell localization in vivo, which is essential to the study of tumor metastasis and in the development of cell-based therapies. While most conventional small-molecule fluorescent probes cannot afford durable cell labeling, transfection of cells with fluorescent proteins is limited by their fixed fluorescence, poor tissue penetration, and interference of autofluorescence background. Here, a bioresponsive near-infrared fluorescent probe is reported as facile and reliable tool for real-time cell tracking in vivo. The design of this probe relies on a new phenomenon observed upon fluorobenzene-conjugated fluorescent dyes, which can form complexes with cytosolic glutathione and actively translocates to lysosomes, exhibiting enhanced and stable cell labeling. Fluorobenzene-coupled hemicyanine, a near-infrared fluorophore manifests to efficiently staining tumor cells without affecting their invasive property and enables persistent monitoring of cell migration in metastatic tumor murine models at high resolution for one week. The method of fluorobenzene functionalization also provides a simple and universal "add-on" strategy to render ordinary fluorescent probes suitable for long-term live-cell tracking, for which currently there is a deficit of suitable molecular tools.

Mapping nanoscale dynamic properties of suspended and supported multi-layer graphene membranes via contact resonance and ultrasonic scanning probe microscopies

Graphene’s (GR) remarkable mechanical and electrical properties—such as its Young’s modulus, low mass per unit area, natural atomic flatness and electrical conductance—would make it an ideal material for micro and nanoelectromechanical systems (MEMS and NEMS). However, the difficulty of attaching GR to supports, coupled with naturally occurring internal defects in a few layer GR can significantly adversely affect the performance of such devices. Here, we have used a combined contact resonance atomic force microscopy (CR-AFM) and ultrasonic force microscopy (UFM) approach to characterise and map with nanoscale spatial resolution GR membrane properties inaccessible to most conventional scanning probe characterisation techniques. Using a multi-layer GR plate (membrane) suspended over a round hole, we show that this combined approach allows access to the mechanical properties, internal structure and attachment geometry of the membrane providing information about both the supported and suspended regions of the system. We show that UFM allows the precise geometrical position of the supported membrane-substrate contact to be located and provides an indication of the local variation of its quality in the contact areas. At the same time, we show that by mapping the position sensitive frequency and phase response of CR-AFM response, one can reliably quantify the membrane stiffness, and image the defects in the suspended area of the membrane. The phase and amplitude of experimental CR-AFM measurements show excellent agreement with an analytical model accounting for the resonance of the combined CR-AFM probe-membrane system. The combination of UFM and CR-AFM provide a beneficial combination for the investigation of few-layer NEMS systems based on two dimensional materials.

FluidFM as a tool to study adhesion forces of bacteria - Optimization of parameters and comparison to conventional bacterial probe Scanning Force Spectroscopy.

The FluidFM enables the immobilization of single cells on a hollow cantilever using relative underpressure. In this study, we systematically optimize versatile measurement parameters (setpoint, z-speed, z-length, pause time, and relative underpressure) to improve the quality of force-distance curves recorded with a FluidFM. Using single bacterial cells (here the gram negative seawater bacterium Paracoccus seriniphilus and the gram positive bacterium Lactococcus lactis), we show that Single Cell Force Spectroscopy experiments with the FluidFM lead to comparable results to a conventional Single Cell Force Spectroscopy approach using polydopamine for chemical fixation of a bacterial cell on a tipless cantilever. Even for the bacterium Lactococcus lactis, which is difficult to immobilze chemically (like seen in an earlier study), immobilization and the measurement of force-distance curves are possible by using the FluidFM technology.

Carbon resistive probe memory designed for ultra-high storage density

Probe-based storage memories are considered one of the most promising solutions to address the mass storage issues in the near future. However, data size arising from conventional probe memories is usually larger than probe size due to the thermal diffusion effect. To eliminate such thermal interference and make data dimension fully dominated by probe dimension, we proposed a concept of carbon-based resistive probe memory and developed a comprehensive computational model to predict its write, rewrite and readout performances governed by electro-thermal and mass concentration processes. The physical reality of such a theoretical model was demonstrated through the good agreement between the calculated and experimental measured threshold voltages for different layered thickness. The data bit of carbon-based resistive probe memory, considered as the sp2 filament inside sp3 background, is formed completely underneath the tip edge due to the localized electric field induced here. This makes the bit size fully determined by the probe tip dimension and allows for the achievement of ultra-high density using an ultra-small probe tip with low energy consumption. Such a conductive filament can be also rewritten back to its pristine sp3 state at relatively high temperature (~250 °C) and detected by sensing the device reading contrast (~1). The designed carbon-based resistive probe memory can retain its bit completeness even if we reduce the bit pitch to 28 nm for a probe size of 25 nm, exhibiting a superior immunity to thermal cross-talk effect. It, however, induces strong readout cross-talk, which is revealed from the resistance image of the multiple bit pattern. This adversely reduces the achievable recording density due to the required large bit pitch, which can be alleviated using either a very sharp tip apex or the optical readout scheme.

Vision-based surface roughness accuracy prediction in the CNC milling process (Al6061) using ANN

This paper proposed the methodology of identified the surface roughness accuracy rate in the CNC milling process by Artificial Neural Network. Al6061 preferred as job material for milling processes carried out in CNC milling machines. The various input parameters like speed, federate, and depth of cut used for the CNC milling process. The Artificial Neural Network modeling has consisted of different input parameters and a single output parameter. The surface roughness is fixed as an output parameter in an Artificial Neural Network. Based on the input parameter and the number of neurons, the surface roughness value was derived. The final accuracy rate of surface roughness was calculated by vision measurement value compared with the conventional stylus probe.

Hidden, entangled and resonating order

In condensed matter systems, the atoms, electrons or spins can sometimes arrange themselves in ways that result in unexpected properties but that cannot be detected by conventional experimental probes. Several historical and contemporary examples of such hidden orders are known and more are awaiting discovery, perhaps in the form of more complex composite, entangled or dynamical hidden orders.