A review on electronic bio-sensing approaches based on non-antibody recognition elements

In this review, recent advances in the development of electronic detection methodologies based on non-antibody recognition elements such as functional liposomes, aptamers and synthetic peptides are discussed. Particularly, we highlight the progress of field effect transistor (FET) sensing platforms where possible as the number of publications on FET-based platforms has increased rapidly. Biosensors involving antibody-antigen interactions have been widely applied in diagnostics and healthcare in virtue of their superior selectivity and sensitivity, which can be attributed to their high binding affinity and extraordinary specificity, respectively. However, antibodies typically suffer from fragile and complicated functional structures, large molecular size and sophisticated preparation approaches (resource-intensive and time-consuming), resulting in limitations such as short shelf-life, insufficient stability and poor reproducibility. Recently, bio-sensing approaches based on synthetic elements have been intensively explored. In contrast to existing reports, this review provides a comprehensive overview of recent advances in the development of biosensors utilizing synthetic recognition elements and a detailed comparison of their assay performances. Therefore, this review would serve as a good summary of the efforts for the development of electronic bio-sensing approaches involving synthetic recognition elements

Detection of matrilysin (MMP-7) activity using polypeptide functionalized reduced graphene oxide field-effect transistor sensor.

A novel approach for rapid and sensitive detection of matrilysin (MMP-7, a biomarker involved in the degradation of vari-ous macromolecules) based on polypeptide (JR2EC) functionalized reduced graphene oxide (rGO) field effect transistor (FET) is reported. MMP-7 specifically digests negatively charged JR2EC immobilized on rGO, thereby modulating the con-ductance of rGO-FET. The proposed assay enabled detection of MMP-7 at clinically relevant concentrations with a limit of detection (LOD) of 10 ng/mL (400 pM), attributed to the significant reduction of the net charge of JR2EC upon digestion by MMP-7. Quantitative detection of MMP-7 in human plasma was further demonstrated with a LOD of 40 ng/mL, illustrating the potential for the proposed methodology for tumor detection and carcinoma diagnostic (e.g. lung cancer and salivary gland cancer). Additionally, excellent specificity of the proposed assay was demonstrated using matrix metallopeptidase 1 (MMP-1), a protease of the same family. With appropriate selection and modification of polypeptides, the proposed assay could be extended for detections of other enzymes with polypeptide digestion capability

Effects of minocycline on cocaine sensitization and phosphorylation of GluR1 receptors in 5-lipoxygenase deficient mice

In wild-type (WT) mice, the antibiotic minocycline inhibits development of cocaine-induced locomotor sensitization. Some of the actions of minocycline may involve the 5-lipoxygenase (5-LOX) pathway. We used the model of 5-LOX-deficient mice to investigate whether 5-LOX participates in minocycline’s influence on the effects of cocaine. Locomotor sensitization was induced by 4 daily cocaine injections and the phosphorylation status of GluR1 glutamate receptors was assayed in brain samples. Minocycline failed to affect cocaine sensitization in 5-LOX-deficient mice. In these mice, neither cocaine nor minocycline 4-day treatment altered GluR1 phosphorylation. In WT mice in which minocycline inhibited development of cocaine sensitization, a 4-day cocaine treatment increased GluR1 phosphorylation at both Ser831 and Ser845 sites in the frontal cortex but not the striatum; further, this effect was prevented by minocycline. Under basal conditions and in response to a single cocaine injection the levels of GluR1, GluR2, and GluR3 AMPA receptor subunits did not differ between WT and 5-LOX-deficient mice, but the response of GluR1 phosphorylation to a single cocaine injection was greater under the 5-LOX deficiency. Hence, in WT mice GluR1 phosphorylation increased only in the frontal cortex and only at the Ser831 site. In 5-LOX-deficient mice, acute cocaine injection increased both Ser831 and Ser845 phosphorylation both in the frontal cortex and in the striatum. We suggest that in studying minocycline’s action on cocaine’s effects and/or addiction in humans, it would be important to consider the characterization of the subjects’ 5-LOX system

Highly <i>trans-</i>Stereoselective Synthesis of Bicyclic Isoxazolidines via Copper-Catalyzed Triple Cascade Catalysis

A triple cascade was developed using a simple copper catalyst to <i>trans</i>-selectively access bicyclic isoxazolidines in a one-pot synthesis. This strategy features the in situ generation of nitrones and subsequent trapping by [3 + 2] cycloaddition. In this method, copper serves three catalytic functions: as a Lewis acid for the ene reaction, as an organometallic for aerobic oxidation, and as a Lewis acid for an <i>endo</i>-selective [3 + 2] cycloaddition. The successful merging of aerobic oxidation and Lewis acid catalysis demonstrated efficient cascade synergy

Highly <i>trans-</i>Stereoselective Synthesis of Bicyclic Isoxazolidines via Copper-Catalyzed Triple Cascade Catalysis

A triple cascade was developed using a simple copper catalyst to <i>trans</i>-selectively access bicyclic isoxazolidines in a one-pot synthesis. This strategy features the in situ generation of nitrones and subsequent trapping by [3 + 2] cycloaddition. In this method, copper serves three catalytic functions: as a Lewis acid for the ene reaction, as an organometallic for aerobic oxidation, and as a Lewis acid for an <i>endo</i>-selective [3 + 2] cycloaddition. The successful merging of aerobic oxidation and Lewis acid catalysis demonstrated efficient cascade synergy

Highly <i>trans-</i>Stereoselective Synthesis of Bicyclic Isoxazolidines via Copper-Catalyzed Triple Cascade Catalysis

A triple cascade was developed using a simple copper catalyst to <i>trans</i>-selectively access bicyclic isoxazolidines in a one-pot synthesis. This strategy features the in situ generation of nitrones and subsequent trapping by [3 + 2] cycloaddition. In this method, copper serves three catalytic functions: as a Lewis acid for the ene reaction, as an organometallic for aerobic oxidation, and as a Lewis acid for an <i>endo</i>-selective [3 + 2] cycloaddition. The successful merging of aerobic oxidation and Lewis acid catalysis demonstrated efficient cascade synergy

Partial moss in different habitats.

Note: 1. Moss on the ground in caves; 2. The moss on the cave wall; 3. Middle moss in the shrub outside the cave; 4. Moss in Farmland Outside the Cave.</p

Effects of magnesium on DNA condensation in the presence of IHF.

<p>(A) Force-extension curves obtained by force jumping. Triangles and circles represent data obtained in the absence and presence of 2 mM MgCl₂, respectively. For 250 nM and 1250 nM IHF, data are not shown for force <0.6 pN because DNA extension was below the minimal extension (∼2 µm) that could be measured by our instrument. (B) DNA folding time course at various values of lower force and unfolding time course at the high force of ∼12 pN in 1250 nM IHF. (C–F) Atomic force microscopy analysis of DNA molecules incubated in 50 mM KCl and 2 mM MgCl₂ with 1250 nM IHF (C), 310 nM IHF (D), 78 nM IHF (E) and 31 nM IHF (F). IHF heterodimer to DNA base pair ratio is indicated in each image panel.</p

Influences of IHF on DNA force response in the absence of magnesium.

<p>(A) Top-panel: Schematic diagram of the transverse magnetic tweezers setup used in this paper. Bottom panel: force-extension curves of λ-DNA according to the Marko-Siggia formula for the protein-free DNA persistence length of 50 nm (black) and a reduced persistence length of 25 nm (red). (B–D) Effects of IHF on the force response of λ-DNA at varying concentrations of KCl and pH 7.4. Force-extension curves of DNA in the force-decreasing (filled triangles) and force-increasing (open triangles) scans at the indicated concentrations of IHF in 200 mM KCl (B), 100 mM KCl (C), and 50 mM KCl (D), respectively. (E) Force-extension curves measured in 50 mM KCl by force jumping. (F) DNA extension as a function of the IHF concentration at 0.1 pN at different KCl concentrations. Data at 0.1 pN were obtained from the force-extension curves at corresponding KCl concentrations in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049885#pone-0049885-g001" target="_blank">Figure 1B–C and 1E</a> by linear interpolation using two nearest neighbouring data points adjacent to 0.1 pN. (G) Decreasing KCl concentration from 200 mM to 50 mM drives a switch from smaller to higher degrees of DNA bending. Filled triangles represent force-extension curves of DNA incubated in 200 mM KCl at the indicated concentration of IHF. Open triangles represent force-extension curves of DNA after lowering the KCl concentration to 50 mM and removing IHF. (H) The DNA bending angle as a function of the spacing of IHF bound to DNA that causes 50% reduction in DNA extension at 0.1 pN.</p

S1 Appendix -

In order to reveal the community characteristics and trophic structure of oribatid mites in different moss habitats in karst caves, the oribatid mites in the moss habitats of ground (GD), understory (US), cave wall (CW), surface shrub (SB) and farmland (FL) outside the cave were collected in October 2021. Through the identification and data analysis of oribatid mites, 2352 oribatid mites were found, belonging to 45 families and 72 genera, most of which were Gymnonota. The family number, genus number, individual number, individual density, dominant genus composition, community diversity, community similarity, MGP (Analysis methods for ecological groups of oribatid mites) ecological group of oribatid mites and trophic structure of oribatid mites in different moss were analyzed. The results showed that: (1) The number of families, genera, individuals, and individual density of SB and FL are higher than those of the other three habitats; (2) Platyliodes, Oppiella, Tectocepheus, Scutovertex, Scheloribates and Trichogalumna are the dominant genera of the oribatid mites in the cave moss habitat, among them, Tectocepheus and Trichogaluna have the most obvious advantages; (3) The diversity index of shrub (SB) was higher than that of other four habitats; Similarity between ground and cave wall, shrub and farmland is high; (4) The MGP ecological group of oribatid mites in different habitats is dominated by O type (Overall type belongs to MGP analysis results, 20%≤M,G,P≤50%), and a total of 42 genera of oribatid mites preliminarily constitute the trophic structure of oribatid mites in the cave moss habitat. Based on the above results, it can be concluded that there are differences in the community structure of oribatid mites in different moss habitats in the study area, and the use of dominant genera of mites can preliminarily indicate the environmental conditions of different moss habitats. This study enriches the study of mites in karst cave mosses, and can provide theoretical significance for the protection of cave biodiversity in karst areas.</div