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A high-charge polymer molecule PEI-oBA is introduced to assisted low molecular weight neutral dextran detection based on nanopipette technology.

The polylactic acid composite films were successfully fabricated via the technique of solvent casting using cellulose acetate (20%, wt) as the reinforcing material and phenyl salicylate as the ultraviolet (UV) absorbent and antibacterial agent. Polylactic acid-cellulose acetate-phenyl salicylate composite films displayed complete absorption effect at the region of UV-C (280-100 nm) and UV-B (315-280 nm), and more than 95% UV absorption effect at the region of UV-A (400-315 nm). These results indicate that the UV shielding performance of the composite films could be significantly improve by addition of phenyl salicylate. Moreover, the addition of 20% phenyl salicylate could improve the steam resistance, mechanical properties and thermal stability of the films, and the composite films had also better antibacterial activity against Escherichia coli. The composite films could reduce the decay rate of fresh lilies and extend their storage time. The degradation characteristics of the films were explored in the natural environment and the laboratory level, which provided application prospect for the development of degradable food packaging materials with anti-ultraviolet and anti-bacteria effect.

Human C-reactive protein (CRP) is an established inflammatory biomarker and was proved to be potentially relevant to disease pathology and cancer progression. A large body of methodologies have been reported for CRP analysis, including electrochemical/optical biosensors, aptamer, or antibody-based detection. Although the detection limit is rather low until pg/uL, most of which are time-consuming and relatively expensive, and few of them provided CRP single-molecule information. This work demonstrated the nanopore-based approach for the characterization of CRP conformation under versatile conditions. With an optimized pore of 14 nm in diameter, we achieved the detection limit as low as 0.3 ng/μL, voltage polarity significantly influences the electro-osmotic force and CRP translocation behavior, and the pentameric conformation of CRP may dissociate into pro-inflammatory CRP isoforms and monomeric CRP at bias potential above 300 mV. CRP tends to translocate through nanopores faster along with the increase in pH values, due to more surface charge on both CRP and pore inner wall and stronger electro-osmotic force. The CRP could specifically bind with its aptamer of different concentrations to form complexes, and the complexes exhibited distinguishable nanopore translocation behavior compared with CRP alone. The variation of the molar ratio of aptamer significantly influences the orientation of CRP translocation. The plasma test under physiological conditions displayed the ability of the nanopore system on the CRP identification with a concentration of 3 ng/μL.

Lipopolysaccharides (LPS) are the major constituent on the cell envelope of all gram-negative bacteria. They are ubiquitous in water, air, and food, and are toxic inflammatory stimulators and optimal biomarkers for some urinary disorders and sepsis. A good many optical, electrical, thermal, and electrochemical sensors based on the intermolecular interplay of LPS with proteins, peptides, and aptamers are reported, they are generally complicated methods. We demonstrate the single-molecule nanopore approach for the identification of LPS from distinct bacteria as well as the discrimination of serotypes from the same bacterium. With a 4 nm nanopore, we achieve a LOD of 10 ng/mL and a linear response up to 10,000 ng/mL. Both the antibiotic PMB and DNA aptamer display good binding affinity to LPS, and the complexes exhibit distinct nanopore translocation behaviors compared with the individual LPS. The real sample tests in both human serum and tap water show good performance characteristics in the identification of LPS in complicated media with a nanopore platforms. Our work shows a highly-sensitive and easy-to-handle scheme for clinical and environmental biomarkers determination and provides a promising screening tool for early warning of contamination in food, water, and medical supplies.

Knowledge of the fate and transport of nanoscale zero-valent iron (nZVI) in saturated porous media is crucial to the development of in situ remediation technologies. This work systematically compared the retention and transport of carboxymethyl cellulose (CMC) modified nZVI (CMC-nZVI) and sulfidated nZVI (CMC-S-nZVI) particles in saturated columns packed with quartz sand of various grain sizes and different surface metal oxide coatings. Grain size reduction had an inhibitory effect on the transport of CMC-S-nZVI and CMC-nZVI due to increasing immobile zone deposition and straining in the columns. Metal oxide coatings had minor effect on the transport of CMC-S-nZVI and CMC-nZVI because the sand surface was coated by the free CMC in the suspensions, reducing the electrostatic attraction between the nZVI and surface metal oxides. CMC-S-nZVI displayed greater breakthrough (C/C

Since the outbreak of COVID-19 in the world, it has spread rapidly all over the world. Rapid and effective detection methods have been a focus of research. The SARS-CoV-2 N protein (NP) detection methods currently in use focus on specific recognition of antibodies, but the reagents are expensive and difficult to be produced. Here, aptamer-functionalized nanopipettes utilize the unique ion current rectification (ICR) of nanopipette to achieve rapid and highly sensitive detection of trace NP, and can significantly reduce the cost of NP detection. In the presence of NP, the surface charge at the tip of the nanopipette changes, which affects ion transport and changes the degree of rectification. Quantitative detection of NP is achieved through quantitative analysis. Relying on the high sensitivity of nanopipettes to charge fluctuations, this sensor platform achieves excellent sensing performance. The sensor platform exhibited a dynamic working range from 10

While it has been recognized that sulfidation can effectively improve the reactivity of microscale zero valent iron (mZVI), there is limited understanding of nitrobenzene (ArNO

Focused ultrasound (FUS) technology attracts increasing interests accrediting to its non-invasive and painless treatment of tumors. Magnetic resonance imaging (MRI) guidance has been introduced to monitor this procedure, thus allowing the ultrasound foci to be precisely controlled. However, manual positioning of the FUS transducers is challenging, especially for the intra-operative (intra-op) adjustment in the MRI room. Currently, there are very few devices capable to provide robotic transducer positioning for the treatment of abdominopelvic organ diseases under MRI. The high intensity focused ultrasound (HIFU) spot would have to be “steered” to ablate large (>O 3.5 cm) or multiple tumors (e.g., in liver). To this end, we proposed a hydraulic-driven tele-operated robot platform that enables 5-DoF manipulation of the FUS transducer. Even operated close to the MRI iso-center, the robot can guarantee zero electromagnetic (EM) artifact to the MR image. Our proof-of-concept robot prototype can offer a large workspace (100 mm × 100 mm × 35 mm) for FUS foci steering. Accurate manipulation (0.2 mm in translation, 0.4° in rotation) of the FUS transducer holder is achieved using rolling diaphragm-sealed hydraulic actuators. The robot control responsiveness (from 0.1 to 4 Hz) is also evaluated to show the potential to compensate for the spot tracking error induced by respiratory motion. We also demonstrate the use of wireless radiofrequency (RF) markers to continuously register the robot task space in the MRI coordinates.

Free-standing nanocrystalline graphite (NCG) membranes directly grew on SiNx substrates with the aid of the catalyst-free chemical vapor deposition method. A new type of NCG nanopore was formed in the NCG membrane via controlled dielectric breakdown in KCl electrolyte. The electrical properties, especially the ionic conductance of the NCG nanoporewere examined under different physical parameters (pore size, ion strength, and pH condition). Due to their impressive transport properties, we first realized DNA sensing using the NCG nanopores.

The formation of G-quadruplexes (G4) in human telomere and other important biological regions inhibits the replication and transcription of DNA, thereby influencing further cell proliferation. The investigation of G4 formation and unfolding is vital for understanding their modulation in biological processes and life science. Photo regulation is a facile and sensitive approach for monitoring the structures of biomacromolecules and material surface properties. The nanopore-based technique is also prevalent for label-free single-molecule characterization with high accuracy. This study provides a combination of solid-state nanopore technology with light-switch as a platform for the modulation of human telomere G4 formation and splitting under switchable light exposure. The introduction of molecular switch, namely azobenzene moiety at different positions of the DNA sequence influences the formation and stability of G4. Three azobenzenes immobilized on each of the G-quartet plane (hTelo-3azo-p) or four azobenzenes on the same plane (hTelo-4azo-4p) of the human telomere G4 sequence realized the reversible control of G4 folding/unfolding at the temporal scale upon photo regulation, and the formation and splitting of G4 with hTelo-4azo-4p is slower and not thorough compared to that with hTelo-3azo-p due to the coplanar steric hindrance. Moreover, the G4 formation recorded with the combined nanopore and photo-responsive approach was also characterized with fluorescence, and the variation in the fluorescence intensity of the NMM and G4 complex exhibited a different tendency under reverse light irradiation due to the distinct interactions of NMM with the azobenzene-modified G4. Our study demonstrated a controllable and sensitive way for the manipulation of G4 structures, which will be inspiring for the intervention of G4-related cell senescence, cancer diagnosis and drug exploration.

In biochemistry, it is crucial to explore the conformation, response to external environment and interaction rules of biomacromolecules and small molecules for understanding the correlation of the structures and properties among organic matters. However, it is a challenge for the traditional techniques to observe the conformation heterogeneity and interpret the interaction mechanism of the biomolecules in living cells. As the emerged the third generation single-molecule gene sequencing technology, nanopore is used to monitor the conformation change of the molecules in situ and therefore demonstrate good applications in single-molecule sensing and nucleic acid and protein sequencing. To further improve the detection resolution and precision, the combined photoelectric detection that can achieve higher accuracy via introducing optical-responsive molecules is adopted. In view of the extensive applications and development status of nanopore technique in single-molecule conformation resolution, this paper summarizes the research progress of the nanopore devices and the design and applications of some typical photo-responsive molecules in nanopore sensing, including azobenzenes and their derivatives (Azos), spiropyrane (SP) and diarylethene (DAE). Light regulation is a simple and effective approach for the monitoring of the molecular structures, and the further integration with nanopore devices exhibits great potential in single-molecule detection meanwhile sheds light on the design and applications of multi-responsive nano-devices.

Dissolved organic matter (DOM) plays a significant role in the transport and transformation of pollutants in the aquatic environment. However, the experimental characterization of DOM has been limited mainly to bulk properties, and the molecular-level interactions among various components of DOM remain to be fully characterized. Here, we use molecular dynamics (MD) simulations to probe the structural properties of model DOM systems at atomic detail. The 200 ns simulations, validated by available experimental data, reveal processes and mechanisms by which chemical species (cations, peptides, lipids, lignin, carbohydrates, and some low-molecular-weight aliphatic and aromatic compounds) aggregate to form complex DOM. The DOM aggregates are dynamic, consisting of a hydrophobic core and amphiphilic exterior. The lipid tails and other hydrophobic fragments form the core, with hydrophilic and amphiphilic groups exposed to water, making DOM accessible to both polar and nonpolar species. Thus, the lipid component acts as a nucleator, whereas cations (especially Ca2+) connect the molecular fragments on the surface by coordinating with the O-containing functional groups of DOM. The structural details revealed here provide new insights including surface accessible atoms, overall assemblage, and interactions among the molecules of DOM for understanding the kinetics and mechanisms through which DOM interacts with metal and other contaminants.

Telomere sequences can spontaneously form G-quadruplexes (G4) in the presence of some cations. In view of their relevance to genetic processes and potential as therapeutic-targets, hitherto, a wealth of conventional techniques have been reported for interrogation of G4 conformation diversity and corresponding folding kinetics, most of which are limited in precision and sensitivity. This work introduces a label-free solid-state nanopore (SSN) approach for the determination of inter-, intra- and tandem molecular G4 with distinct base permutation in various cation buffers with a tailored aperture and meanwhile captures the single-molecule G4 folding process. SSN translocation properties elucidated that both inter- and intramolecular G4 generated higher current blockage with longer duration than flexible homopolymer nucleotide, and intramolecular G4 are structurally more stable with higher event frequency and longer blockage time than intermolecular ones; base arrangement played weak role in translocation behaviors; the same sequences with one, two and three G4 skeletons displayed an increase in current blockage and a gradual extension in dwell time with the increase of molecule size recorded in the same nanopore. We observed the conformation change of single-molecule G4 which indicated the existence of folding/unfolding equilibration in nanopore, and real-time test suggested a gradual formation of G4 with time. Our results could provide a continued and improved understanding of the underlying relevance of structural stability and G4 folding process by utilizing SSN platform which exhibits strategic potential advances over the other methods with high spatial and temporal resolution.

Dielectric breakdown technique was utlised to fabricate 5-6 nm nanopores for vanillin detection in various food samples. A highly selective aptamer (Van_74) with high binding affinity towards vanillin was used as capture probe. Under optimal conditions, aptamer/vanillin complex translocation induced deeper events than the bare aptamer. As a result, the proposed nanopore aptasensor exhibits a linear range from 0.5 to 5 nM (R

In this paper, a novel detection technique for tumor marker carcinoembryonic antigen (CEA) has been developed by using a solid-state nanopore as a tool. The system utilizes the specific affinity between aptamer-modified magnetic Fe

Nonribosomal peptides (NRPs) are a type of secondary metabolites mostly originated from microorganisms such as bacteria and fungi. Their proteolytic stability, highly selective bioactivity, and microorganism-specificity have made them an attractive source of drugs for the pharmaceutical industry. Herein, with microcystins (MCs) as a NRP model, we, for the first time, proposed a sensitive method to study the interactions between NRPs and the protein nanopore. Due to the large molecular size (~3 nm diameter) of MCs and their net negative charges, MCs failed to translocate through the α-hemolysin (α-HL) protein channel. Our results demonstrated that the biomolecular interaction of MC-α-HL protein was significantly affected by the applied potential bias. The constant blockage amplitude in the voltage-dependent studies indicated that the current modulation events were dominantly contributed to the bumping interaction between MCs and the α-HL protein under the electrophoretic force. The mean residence time of the bumping events exhibited a two-stage decrease (from 1.90 ms to 1.02 ms, and from 1.02 ms to 0.69 ms) at the threshold voltages of −70 mV and −100 mV, respectively. Using our strategy (i.e., based on their electrophoretic driven interaction with the α-HL protein pore), discrimination of different MC molecules (MC-LR, MC-RR, MC-YR and linear analog) with varied branched residues could be accomplished. This work should provide an insight in developing a rapid and effective method for the identification of cyclic NRPs as valuable biomarkers for fungal infections.

Sulfidated zero-valent iron (S-ZVI) enhances the degradation of chlorinated hydrocarbon (CHC) in contaminated groundwater. Despite numerous studies of S-ZVI, a versatile strategy to improve its dechlorination kinetics, electron efficiency (ee), and dechlorination capacity is still needed. Here, we used heteroatom incorporation of N(C) and S by ball-milling of microscale ZVI with melamine and sulfur via nitridation and sulfidation to synthesize S-N(C)-mZVIbm particles that contain reactive Fe-NX(C) and FeS species. Sulfidation and nitridation synergistically increased the trichloroethene (TCE) dechlorination rate, with reaction constants kSA of 2.98 × 10-2 L·h-1·m-2 by S-N(C)-mZVIbm, compared to 1.77 × 10-3 and 8.15 × 10-5 L·h-1·m-2 by S-mZVIbm and N(C)-mZVIbm, respectively. Data show that sulfidation suppressed the reductive dissociation of N(C) from S-N(C)-mZVIbm, which stabilized the reactive Fe-NX(C) and reserved electrons for TCE dechlorination. In addition to lowering H2 production, S-N(C)-mZVIbm dechlorinated TCE to less reduced products (e.g., acetylene), contributing to the material's higher ee and dechlorination capacity. This synergistic effect on TCE degradation can be extended to other recalcitrant CHCs (e.g., chloroform) in both deionized and groundwater. This multiheteroatom incorporation approach to optimize ZVI for groundwater remediation provides a basis for further advances in reactive material synthesis.

HIV-1 Tat protein, an intercellular transporter with a determinant function of delivering "information-rich" molecules in viral multiplication, was tryptic-hydrolyzed and real-time single molecule-monitored in a transmembrane pore. The electrokinetic studies revealed the catalytic and inhibitory effects on enzymatic digestion associated with Ca2+ and Cu2+ ions, respectively, in response to binding interactions with trypsin. Our strategy permits accurate and distinguishable sensing of Ca2+ and Cu2+via an enzyme assay. In addition, considering the closer mimic of the real situation of HIV spread, measurements in the serum and on cells were also investigated. Transmembrane current measurements together with fluorescence microscopy imaging indicated the potential to perturb the Tat transport in the serum environment and on cells. Because the involved Tat proteolysis should prevent the occurrence of viral delivery, the presented method probably enables efficient hindrance to HIV-1 infection, in complementary to current traditional treatments.

Nanopore is used as a single-molecule detector for proteins, peptides and amino acids identification of biomedical importance. We, on the first try, extended its profiling application for peptidome encoded by the insect-resistance gene in rice. Taking brown planthopper (Bph) for example, we previously cloned and verified Bph32 gene, which encodes SCR ("Bph32") protein as direct executor against this injurious insect. However, the homology protein expressed in susceptible line doesn't have this antibiosis resistance. Hence, profiling the structural modulars (peptide domains) of Bph32 proteins may provide essential basis to understand rice in response to insects. Herein, we combined approaches of bioinformatics, biochemistry and nanopore analysis to profile the rice peptides with diverse properties. Bph32 proteins were theoretically modeled into 24 functional peptide domains using Swiss-Model workspace. Next, 22 water-soluble peptides were identified by biuret-chemistry amplified nanopore current modulations. Among those, 16 ones were distinguished at one amino acid resolution via reading the current modulation spectrum, consequently providing the peptidome fingerprints. In addition, the current modulations were evidenced as quadratic function of peptide's molecular masses. These findings suggest that nanopore may work as a new generation of mass detector for more omics analysis, especially in agricultural field where demands strongly.

BACKGROUND Single-shot diffusion-weighted imaging (ssDWI) has been shown useful for detecting active bowel inflammation in Crohn's disease (CD) without MRI contrast. However, ssDWI suffers from geometric distortion and low spatial resolution. PURPOSE To compare conventional ssDWI with higher-resolution ssDWI (HR-ssDWI) and multi-shot DWI based on multiplexed sensitivity encoding (MUSE-DWI) for evaluating bowel inflammation in CD, using contrast-enhanced MR imaging (CE-MRI) as the reference standard. STUDY TYPE Prospective. SUBJECTS Eighty nine patients with histological diagnosis of CD from previous endoscopy (55 male/34 female, age: 17-69 years). FIELD STRENGTH/SEQUENCES: ssDWI (2.7 mm × 2.7 mm), HR-ssDWI (1.8 mm × 1.8 mm), MUSE-DWI (1.8 mm × 1.8 mm) based on echo-planar imaging, T2-weighted imaging, and CE-MRI sequences, all at 1.5 T. ASSESSMENT Five raters independently evaluated the tissue texture conspicuity, geometry accuracy, minimization of artifacts, diagnostic confidence, and overall image quality using 5-point Likert scales. The diagnostic performance (sensitivity, specificity and accuracy) of each DWI sequences was assessed on per-bowel-segment basis. STATISTICAL TESTS Inter-rater agreement for qualitative evaluation of each parameter was measured by the intra-class correlation coefficient (ICC). Paired Wilcoxon signed-rank tests were performed to evaluate the statistical significance of differences in qualitative scoring between DWI sequences. A P value

The kinetics of mercuric ion (Hg2+) binding with heterogeneous naturally dissolved organic matter (DOM) has been hypothesized to result from competitive interactions among different organic ligands...