A voltammetric sensor for bisphenol A using gold nanochains and carbon nanotubes.

Gold nanochains (AuNCs) were prepared, and this novel material was combined with carboxylated multi-walled carbon nanotubes (cMWCNTs) to be a nanocomposite for the first time. The transmission electron microscopy (TEM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and UV-Vis spectra were used to characterize the successful preparation of AuNCs and AuNC-cMWCNT composite. Based on this hybrid material, a voltammetric sensor of bisphenol A (BPA) was established. The proposed sensor displayed excellent performance for the measurement of BPA by obvious decreased anodic peak potential and enlarged peak current. Using the optimized conditions, BPA was detected using linear sweep voltammetry, and the linear range showed as wide as 0.5 µM to 2000 µM with the detection limit estimated to be 12 nM (S/N = 3). The as-proposed sensor also exhibited satisfactory performance in determining BPA of actual plastic samples.

A miniaturized electrochemical device integrating a biconical microchannel and carbon fiber disk ultramicroelectrode.

A simple, cheap and practicable miniaturized electrochemical device based on a biconical microchannel was developed, for which only 1 µL sample solution was needed to implement a typical electrochemical experiment. The practicability of the designed device was validated by detecting uric acid as a model molecule in human serum.

Distribution of high-risk human papillomavirus genotypes in HPV-infected women in Beijing, China.

To investigate the distribution of high-risk human papillomavirus (HPV) genotypes in infected women from Beijing, China, samples were obtained during routine gynecologic examinations and DNA was extracted from the samples, and PCR was performed to distinguish the 13 high-risk HPV subtypes (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). Samples were obtained from 1160 women (20-75 years old), and 470 cases of high-risk HPV infection were diagnosed. HPV 52, HPV 16, HPV 58, HPV 51, and HPV 39 were the most common genotypes accounting for 22.8%, 22.3%, 20.0%, 14.3%, and 13.6% of cases, respectively. The highest infection rates were found in 20-30 year-old patients (35.1%). HPV 16 infection was the highest in the 31-40 year-old group, and HPV 52, HPV 58, and HPV 39 infections were highest in the 20-30 year-old group. Some patients were infected with multiple high-risk HPV subtypes. Of the 470 patients with positive HPV tests, 65.7% of women were infected with a single high-risk HPV subtype, 23.2%, of women were infected with two high-risk HPV subtypes, 7.7% were infected with three subtypes, and 3.4% of women were infected with more than three high-risk HPV subtypes. In this study, HPV 16 and HPV 52 were the most common subtypes found in patients with cervical lesions.

A novel electrochemical chiral sensor for 3,4-dihydroxyphenylalanine based on the combination of single-walled carbon nanotubes, sulfuric acid and square wave voltammetry.

We demonstrate, for the first time, an electrochemical sensor that provides antipodal signals upon application of square wave voltammetry (SWV), for enantioselective recognition of 3,4-dihydroxyphenylalanine based on chiral single-walled carbon nanotubes (SWCNTs) in the presence of sulphuric acid. Interestingly, the enantioselectivity was not observed using the common method of cyclic voltammetry (CV) but the SWV peak currents of enantiomers were found to be quite different and hence the enantiomers could be successfully recognized. Moreover, the antipodal signals provided by two SWV scan modes offer the possibility for results to be confirmed mutually, showing a great practical value and analytical application prospects.

Electrochemical sensing performance of two CuO nanomaterial-modified dual-working electrodes.

Two CuO nanostructures, namely, nanospheres (CuONSs) and nanochains (CuONCs) with different shapes but similar diameters, were synthesized and characterized. With these two nanomaterials as electrode modifiers, a systematic comparative study was conducted to examine their electrochemical sensing of catechol (CT) using a dual-working electrode system. The results suggest that for CuONS- and CuONC-modified glassy carbon electrodes, the electrode process for the CT redox is diffusion-controlled, and the modification amount and electrolyte pH have a similar effect on the response. However, the CuONCs showed a higher peak current and lower peak potential, as well as a lower detection limit for the electrochemical oxidation of CT. This is explained by the lower charge transfer impedance and higher electroactive surface area of the CuONCs. Notably, an unexpected peak appeared in the cyclic voltammograms when the pH was <4 for the CuONCs and <3 for the CuONSs. For this phenomenon, UV-Vis spectra, zeta potential, and size distribution experiments demonstrated changes in the two CuO nanostructures at lower pH, illustrating that CuONSs can tolerate a higher pH as compared to CuONCs. The multiple comparisons between the two nanomaterials presented here can provide references for the selection of electrochemical sensing materials.

CeRNA network identified hsa-miR-17-5p, hsa-miR-106a-5p and hsa-miR-2355-5p as potential diagnostic biomarkers for tuberculosis.

This study aims to analyze the regulatory non-coding RNAs in the pathological process of tuberculosis (TB), and identify novel diagnostic biomarkers. A longitudinal study was conducted in 5 newly diagnosed pulmonary tuberculosis patients, peripheral blood samples were collected before and after anti-TB treatment for 6 months, separately. After whole transcriptome sequencing, the differentially expressed RNAs (DE RNAs) were filtrated with |log2 (fold change) | > log2(1.5) and P value < .05 as screening criteria. Then functional annotation was actualized by gene ontology enrichment analysis, and enrichment pathway analysis was conducted by Kyoto Encyclopedia of Genes and Genomes database. And finally, the competitive endogenous RNA (ceRNA) regulatory network was established according to the interaction of ceRNA pairs and miRNA-mRNA pairs. Five young women were recruited and completed this study. Based on the differential expression analysis, a total of 1469 mRNAs, 996 long non-coding RNAs, 468 circular RNAs, and 86 miRNAs were filtrated as DE RNAs. Functional annotation demonstrated that those DE-mRNAs were strongly involved in the cellular process (n = 624), metabolic process (n = 513), single-organism process (n = 505), cell (n = 651), cell part (n = 650), organelle (n = 569), and binding (n = 629). Enrichment pathway analysis revealed that the differentially expressed genes were mainly enriched in HTLV-l infection, T cell receptor signaling pathway, glycosaminoglycan biosynthesis-heparan sulfate/heparin, and Hippo signaling pathway. CeRNA networks revealed that hsa-miR-17-5p, hsa-miR-106a-5p and hsa-miR-2355-5p might be regarded as potential diagnostic biomarkers for TB. Immunomodulation-related genes are differentially expressed in TB patients, and hsa-miR-106a-5p, hsa-miR-17-5p, hsa-miR-2355-5p might serve as potential diagnostic biomarkers.

Simultaneous determination of hydroquinone and catechol by a reduced graphene oxide-polydopamine-carboxylated multi-walled carbon nanotube nanocomposite.

A reduced graphene oxide-polydopamine-carboxylated multi-walled carbon nanotube (RGO-PDA-cMWCNT) nanocomposite was fabricated via a facile, one-pot procedure and was characterized by a variety of techniques. A novel electrochemical sensor based on RGO-PDA-cMWCNT was constructed to determine hydroquinone (HQ) and catechol (CT) simultaneously. This newly prepared nanocomposite shows excellent electrocatalytic efficacy in the electrode reaction of the two isomers. Specifically, the peak-to-peak potential difference between the two dihydroxybenzenes is 115 mV for oxidation, which is obviously larger than similar electrochemical sensors. The established method displays a wide linear range from 0.5 to 5000 µM with a detection limit (S/N = 3) of 0.066 µM for HQ and 0.073 µM for CT. In addition, this electrochemical approach has been tested to measure the two dihydroxybenzenes in real samples and satisfactory results were recorded.

The facile approaches to asymmetric modification of glassy biconical microchannel wall with silver, copper or gold.

The modification of inner surface has significant influence in the properties of the nano or microchannel based on various materials, especially for the ionic current rectification (ICR) that arises from the selective interaction between ions in solution and the inner surface. Herein, we demonstrate a simple strategy to asymmetrically modify the inner wall of a glassy biconical microchannel with silver, copper or gold by means of silver mirror reaction and polydopamine platform, respectively. And the bidirectional ionic current rectification phenomena were observed in all of the modified biconical microchannels. All of the modification methods are simple, facile and low-cost, and can be applied in the modification of other glassy pipettes.

The fabrication of carbon nanotubes array-based electrochemical chiral sensor by electrosynthesis.

How to align the single-walled carbon nanotubes (SWCNTs) onto the electrode vertically and to control their density and orientation are still a major challenge. Theoretically, properly selected chiral SWCNTs can discriminate enantiomers through their different dielectric response to the adsorption of chiral species, few reports can confirm this theoretic model. Herein, we presented a new strategy to fabricate SWCNTs array-based electrochemical chiral sensor. Carboxylated chiral SWCNTs were vertically attached to the oxidized glass carbon electrode with ethylenediamine as a linker by electrosynthesis. The electrode surface was characterized with atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). The practicability of the sensor was validated by chirally recognizing 3,4-dihydroxyphenylalanine as a model molecule. We found that both the highly ordered standing of SWCNTs and the application of square wave voltammetry (SWV) amplified the intrinsic chirality of chiral SWCNTs.

Investigation and application of photochemically induced direct UV detection of low or non-UV absorbing compounds by capillary electrophoresis.

Some low or non-UV absorbing compounds like amino acids might be accessible to direct UV detection by capillary electrophoresis (CE), due to the photochemical reaction in the detection window of the separation capillary under extremely strong alkaline conditions. However, with regards to the photochemical reaction procedure and the influencing factors in CE, no comprehensive studies have been done. Herein, two strategies were applied to investigate the photochemical reaction mechanism including the introduction of an additional UV lamp and the utilization of driving pressure. The former confirmed the occurrence of photolysis, while the latter solved the interference of electroosmotic flow (EOF). Furthermore, the online photochemical reaction and online preconcentration technique were combined to develop a rapid, simple and sensitive method for determination of seven essential amino acids (valine, leucine, phenylalanine, methionine, tryptophan, threonine and lysine). Eventually, the developed method was successfully applied to the analysis of real samples with good reproducibility and reliability. This novel and simple method, based on the photochemical reactions occurring in the detection window and coupling with online preconcentration techniques, shows a great potential for the rapid and sensitive detection of low or non-UV absorbing compounds.

A bidirection-adjustable ionic current rectification system based on a biconical micro-channel.

We developed a simple, cheap and bidirectional ionic current rectification system based on the integration of a biconical micro-channel, working electrode and reference electrode. This system may have potential and realistic future value for studying two-way ionic transport in the cell membrane.