Correlation of systemic immune-inflammatory response index with clinical data in patients with malignant ovarian tumor.

OBJECTIVE: To determine the correlation of the systemic immune-inflammatory response index (SIRI) with clinical data in patients with malignant ovarian tumor. METHODS: The clinical data of 118 patients with ovarian cancer (OC) treated in Ningbo Women's and Children's Hospital from February 2016 to January 2018 were retrospectively studied. Patients were divided into high and low SIRI expression groups according to the receiver operator curve (ROC) optimal cut-off (Cut-off) value, and the association of SIRI with the patient's clinical data was analyzed. Cox regression was adopted for the analysis of prognostic factors impacting the patients' 5-year survival. The associations of SIRI with tumor markers were also analyzed. A risk prediction model was constructed based on the Cox regression coefficient. RESULTS: The group of patients who died showed notably higher neutrophil (NEUT) and SIRI levels than the surviving group, and also showed a significantly lower lymphocyte (LYM) level than the surviving group (P < 0.001). The areas under the ROC curves (AUC) for CA125, NEUT, LYM, and SIRI for predicting death from OC were 0.779, 0.754, 0.776, and 0.848, respectively. In addition, the AUC of each index was ranked CA125 > SIRI > LYM > NEUT. The high-expression group had a higher proportion of patients with stage III-IV and lymph node metastasis (LNM) than the low-expression group (P < 0.05). SIRI showed a positive correlation with serum carbohydrate antigen 125 (CA125), CA153, and HE4 (all P < 0.05), but had no correlation with CA199, AFP, or CEA (all P > 0.05). According to multivariate Cox regression analysis, age, FIGO stage, SIRI, and therapeutic regimen were independent prognostic factors for the 5-year survival of OC patients (all P < 0.05). The risk score was significantly higher in the death group than that in the surviving group (P < 0.001), and the AUC of this risk score for predicting 5-year survival was 0.876. CONCLUSION: Patients with an increased SIRI level account for a large proportion of OC patients with a high FIGO stage and LNM. The 5-year survival rate of patients with a high SIRI level is unfavorable, suggesting the use of SIRI as an observation index for the prognosis of OC.

Directed evolution of a neutrophilic and mesophilic methanol dehydrogenase based on high-throughput and accurate measurement of formaldehyde.

Methanol is a promising one-carbon feedstock for biomanufacturing, which can be sustainably produced from carbon dioxide and natural gas. However, the efficiency of methanol bioconversion is limited by the poor catalytic properties of nicotinamide adenine dinucleotide (NAD+)-dependent methanol dehydrogenase (Mdh) that oxidizes methanol to formaldehyde. Herein, the neutrophilic and mesophilic NAD+-dependent Mdh from Bacillus stearothermophilus DSM 2334 (MdhBs) was subjected to directed evolution for enhancing the catalytic activity. The combination of formaldehyde biosensor and Nash assay allowed high-throughput and accurate measurement of formaldehyde and facilitated efficient selection of desired variants. MdhBs variants with up to 6.5-fold higher Kcat/KM value for methanol were screened from random mutation libraries. The T153 residue that is spatially proximal to the substrate binding pocket has significant influence on enzyme activity. The beneficial T153P mutation changes the interaction network of this residue and breaks the α-helix important for substrate binding into two short α-helices. Reconstructing the interaction network of T153 with surrounding residues may represent a promising strategy to further improve MdhBs, and this study provides an efficient strategy for directed evolution of Mdh.

Photoelectrochemical Immunosensor Based on a 1D Fe2O3/3D Cd-ZnIn2.2Sy Heterostructure as a Sensing Platform for Ultrasensitive Detection of Neuron-Specific Enolase.

Lung cancer is a high-mortality cancer related to the concentration of neuron-specific enolase (NSE). In this work, a sandwich-type photoelectrochemical (PEC) immunosensor was constructed for ultrasensitive detection of NSE, which is based on iron trioxide/indium zinc cadmium sulfide (Fe2O3/Cd-ZnIn2.2Sy) as a sensing platform and Ag-modified polyaniline (Ag@PANI) as a signal amplification label. The 1D Fe2O3 porous nanorods with a large specific surface area were synthesized by calcination of Fe-MIL-88A and etching of NaOH. To improve the photocurrent response, the 3D architecture Cd-ZnIn2.2Sy was combined with the 1D Fe2O3 porous nanorods to form a 1D Fe2O3/3D Cd-ZnIn2.2Sy heterostructure. Specifically, the Fe2O3/Cd-ZnIn2.2Sy heterostructure with a good energy level matching (the two can form a stepped energy level matching, which accelerates the transfer rate of electrons) can improve the separation efficiency of electron-hole pairs (e-/h+) under visible light irradiation, which enhances the photocurrent response. Ag@PANI has a strong electron transport capability and can be used as a secondary antibody marker for the signal amplification of the immunosensor. The sensor exhibits a good linear detection range of 100 fg/mL to 100 ng/mL with a low detection limit of 33.5 fg/mL. Moreover, the constructed sandwich-type PEC immunosensor shows good performance and possesses excellent specificity, selectivity, and stability over a period of 4 weeks for NSE detection. With these excellent properties, the immunosensor can be extended to analyze and diagnose other disease biomarkers.

Ultrasensitive Photochemical Immunosensor Based on Flowerlike SnO2/BiOI/Ag2S Composites for Detection of Procalcitonin.

Based on the necessity and urgency of detecting infectious disease marker procalcitonin (PCT), a novel unlabeled photoelectrochemical (PEC) immunosensor was prepared for the rapid and sensitive detection of PCT. Firstly, SnO2 porous nanoflowers with good photocatalytic performance were prepared by combining hydrothermal synthesis and calcining. BiOI nanoflowers were synthesized by facile ultrasonic mixed reaction. Ag2S quantum dots were deposited on SnO2/BiOI composites by in situ growth method. The SnO2/BiOI/Ag2S composites with excellent photoelectric properties were employed as substrate material, which could provide significantly enhanced and stable signal because of the energy level matching of SnO2, BiOI and Ag2S and the good light absorption performance. Accordingly, a PEC immunosensor based on SnO2/BiOI/Ag2S was constructed by using the layered modification method to achieve high sensitivity analysis of PCT. The linear dynamic range of the detection method was 0.50 pg·mL-1~100 ng·mL-1, and the detection limit was 0.14 pg·mL-1. In addition, the designed PEC immunosensor exhibited satisfactory sensitivity, selectivity, stability and repeatability, which opened up a new avenue for the analyzation of PCT and further provided guidance for antibiotic therapy.

Hollow performances quenching label of Au NPs@CoSnO3 nanoboxes-based sandwich photoelectrochemical immunosensor for sensitive CYFRA 21-1 detection.

In this work, a fire-new "signal-off" type photoelectrochemical (PEC) immunosensor based on bismuth sulfide/iodine doped bismuth oxychloride (Bi2S3/I:BiOCl) heterostructure as a platform and Au nanoparticles loaded hollow CoSnO3 nanoboxes (Au NPs@CoSnO3) as quenching label was designed, for sensitive detection of CYFRA 21-1. The I:BiOCl with flower-like structure could supply high specific surface area for loading nanometer materials. Then, Bi2S3 was formed in-situ by S2- adsorption on the surface of I:BiOCl by dangling bond of Bi3+, but did not change the flower-like structure of I:BiOCl. Then, n-type Bi2S3 and p-type I:BiOCl heterostructure showed good photoelectric behavior by providing an additional electric field to accelerate electron-hole separation. Furthermore, the production process of the heterostructure was simple, fast, low temperature, and without complex raw materials. The Au NPs@CoSnO3 with good photocatalytic activity could strongly compete with Bi2S3/I:BiOCl for electron donor of ascorbic acid (AA). Meanwhile, the CoSnO3 with hollow structure made the quenching effect more significant by the light-scattering effect that enhanced the light absorption capacity and shorten distance of carrier transport. Under optimal conditions, this proposed strategy displayed the low detection limit of 30 fg/mL, with a high linearity range from 100 fg/mL to 100 ng/mL for tumor markers CYFRA 21-1. Simultaneously, it also exhibited excellent specificity and acceptable stability, which might provide a new perspective for the fabrication of other PEC immunosensors with heterostructure simple synthesis and hollow materials.

Self-Powered Cathodic Photoelectrochemical Aptasensor Comprising a Photocathode and a Photoanode in Microfluidic Analysis Systems.

An intriguing self-powered cathodic photoelectrochemical (PEC) microfluidic aptasensor with enhanced cathodic photocurrent response is proposed for sensitive detection of prostate-specific antigen (PSA). The self-powered system is constructed by a cadmium sulfide-sensitized zinc oxide nanorod array (CdS/ZnO NA) as a photoanode with an iodide-doped bismuth oxychloride flower-array (I0.2:BiOCI0.8) as a photocathode, which can generate the electrical output under visible light irradiation with no external power supply. In addition, the p-type semiconductor I0.2:BiOCI0.8 with a special internal electric field between the iodide ion layer and the [Bi2O2]2+ layer could increase the cathodic photocurrent response by facilitating the separation of electron/hole pairs under visible light excitation. It is worth noting that dissolved oxygen as an electron acceptor can be reduced by the photogenerated electron to form a superoxide radical (•O2-) in the self-powered cathodic PEC system. The further enhanced cathodic photocurrent response can be achieved by eliminating •O2- that reacts with the luminol anion radical (L•-) to produce chemiluminescence emission, which serves as an inner excitation light source. What is more exciting is that the integration of the photoanode and the photocathode into a microfluidic chip could realize automatic sample injection and detection. On this basis, the proposed aptasensor presents excellent reproducibility and high sensitivity for detecting PSA and exhibits a good linearity range (50 fg·mL-1 to 50 ng·mL-1) with a low detection limit (25.8 fg·mL-1), which opens up a new horizon of potential for sensitively detecting other kinds of disease markers.

A microfluidic cathodic photoelectrochemical biosensor chip for the targeted detection of cytokeratin 19 fragments 21-1.

A microfluidic chip integrated with a microelectrode and a cathodic photoelectrochemical (PEC) biosensor for the ultrasensitive detection of non-small cell lung cancer cytokeratin fragments based on a signal amplification strategy was designed. The mechanism for signal amplification is developed based on the p-n junction of AgI/Bi2Ga4O9, with dissolved O2 as an electron acceptor to produce the superoxide anion radical (˙O2-) as the working microelectrode. By combining this with a novel superoxide-dismutase-loaded honeycomb manganese oxide nanostructure (SOD@hMnO2) as the co-catalyst signal amplification label, ˙O2- can be catalyzed by SOD via a disproportionation reaction to produce O2 and H2O2; then, hMnO2 is able to trigger the decomposition of H2O2 to generate O2 and H2O. Therefore, the increased O2 promotes the separation of electron-hole pairs via consuming more electrons, leading to an effective enhancement of the cathodic PEC behavior. Under optimum conditions, with the cytokeratin 19 fragments 21-1 (CYFRA 21-1) as the targeted detection objects, the microfluidic cathodic PEC biosensor chip exhibited excellent linearity from 0.1 pg mL-1 to 100 ng mL-1, with a detection limit of 0.026 pg mL-1 (S/N = 3). The exciting thing that this work offers is a new strategy for the detection of other important cancer biomarkers for disease diagnosis and prognosis.

Etching Triangular Silver Nanoparticles by Self-generated Hydrogen Peroxide to Initiate the Response of an Electrochemiluminescence Sensing Platform.

This work outlines a versatile and high-performance electrochemiluminescence (ECL) platform that uses complex luminescent molecules [Ru(II) complex] formed by carbohydrazide (CON4H6) and tris(4,4'-dicarboxylicacid-2,2'-bipyridyl)ruthenium(II) dichloride [Ru(dcbpy)32+] as emitters to facilitate the intramolecular ECL mechanism for reducing the response distance and interference, and they were kept immobilized on a porous bismuth vanadate nanoarray (BiVO4 NA) to improve the orderliness of electron transfer. In addition, the detection was made depending on the etching of triangular silver nanoparticles (T-Ag NPs) by self-generated hydrogen peroxide (H2O2) to initiate the recovery response of the originally quenched ECL due to ECL-RET between the Ru(II) complex (donor) and T-Ag NPs (receptor). Because of the antibacterial application of dopamine, its own redox ability could produce more H2O2 for etching receptor T-Ag NPs under near-infrared (NIR) stimulation. Notably, in this system, the specific binding of antigens and antibodies with the autogenesis process of H2O2 and the ECL detection procedure are independent. Therefore, the proposed system can avert the impact of complex biological samples effectively, and the ECL efficiency of the Ru(II) complex can be readily utilized. On this basis, a biosensor is explored for the primary diagnosis of squamous cell carcinoma by detecting the biomarker named after cytokeratin fragment 19 (CYFRA21-1), from which an excellent linearity from 0.1 pg/mL to 50 ng/mL is achieved with a detection limit of 0.058 pg/mL. All of these results confirmed that this strategy can be a promising candidate for fabricating an ECL-based biosensor.

A self-powered photoanode-supported photoelectrochemical immunosensor for CYFRA 21-1 detection based on In2O3/In2S3/CdIn2S4 heterojunction.

A self-powered photoanode-supported photoelectrochemical (PEC) immunosensor was designed based on In2O3/In2S3/CdIn2S4 as photoanode and PDA@CNTs as biocathode for the detection of CYFRA 21-1. In this proposal, In2O3/In2S3/CdIn2S4 heterojunction modified indium-tin oxide (ITO) electrode was served as a substitute for platinum (Pt) counter electrode to provide an evident and stable photocurrent signal. The matched band structure of In2O3, In2S3 and CdIn2S4 as well as the unique hollow porous structure of In2O3/In2S3/CdIn2S4 played a pivotal role in accelerating the separation and transfer of photocarrier. Meanwhile, PDA@CNTs with excellent conductivity further enhanced the photocurrent which was provided by photoanode In2O3/In2S3/CdIn2S4 heterojunction. Besides, PDA could effectively capture the antibody (Ab) through Michael addition. Separating photoanode from the sensing biocathode was conducive to improve the anti-interference capability of PEC sensor because the reductive species in biologic media will change PEC properties of the photoanode interface. Under optimal conditions, the PEC immunosensor have realized the detection of CYFRA 21-1 (0.5 pg/mL - 50 ng/mL) and the detection limitation with 0.16 pg/mL. In addition, the proposed self-powered PEC sensor with acceptable selectivity, reproducibility, and stability provide a new horizon for designing PEC immunosensing platform in bioassays.

A self-powered photoelectrochemical cathodic aptasensor for the detection of 17ß-estradiol based on FeOOH/In2S3 photoanode.

In this work, a novel self-powered photoelectrochemical (PEC) aptasensor integrated photoanode and photocathode for the accurate and selective detection of 17ß-estradiol (E2) was proposed for the first time. FeOOH/In2S3 heterojunction was built initially and used as a substitute for platinum (Pt) counter electrode. The matched band gap edge of FeOOH and In2S3 facilitated the transfer of photo-generate electrons to photoanode, while the holes left in the valence band of photocathode (CuInS2) can be attracted by the electrons flowed from the photoanode, which reduced the recombination of electron-hole pairs and promote the cathodic photocurrent. Under optimal conditions, the constructed cathodic aptasensor of E2 presented linear scope in 10 fg/mL-1 µg/mL with detection limit of 3.65 fg/mL. Besides, the cathodic aptasensor exhibited admiring selectivity, stability and reproducibility. This work verified that the cathodic photocurrent response can be regulated by the corresponding photoanode which provided a new design thought for PEC aptasensor on the basis of p-type semiconductor.

Facile fabrication of visible light photoelectrochemical immunosensor for SCCA detection based on BiOBr/Bi2S3 heterostructures via self-sacrificial synthesis method.

A novel visible light photoelectrochemical immunosensor based on BiOBr/Bi2S3 heterostructures was fabricated to detect squamous cell carcinoma antigen (SCCA). Bi2S3 nanoparticles formed on the BiOBr microflowers by the self-sacrificial synthesis method based on the facile reaction between BiOBr and S2- ions. The BiOBr/Bi2S3 composites exhibited excellent visible light photoelectrochemical activity, when ascorbic acid (AA) was employed as a perfect electron donor. The photocurrent intensity of BiOBr/Bi2S3 modified ITO electrode arrived at around 20 µA, which was approximately 30 times than that of pure BiOBr. Dopamine formed easily polydopamine film via self-polymerization on the surface of BiOBr/Bi2S3 composites to immobilize SCCA antibody. Under the optimal condition, this photoelectrochemical immunosensor realized the ultrasensitive determination of SCCA. With the logarithm of SCCA concentration in the range of 0.001-75 ng mL-1, the specific binding between SCCA and antibody led to the linearly decrease of photocurrent signal with a low detection limit of 0.3 pg mL-1 (S/N = 3). This facilely constructed photoelectrochemical immunosensor maybe have promising practical application in photocatalysis, analytical detection and biosensor, etc.

Label-free photoelectrochemical immunosensor for NT-proBNP detection based on La-CdS/3D ZnIn2S4/Au@ZnO sensitization structure.

A new, photoelectrochemical immunosensor was proposed on the basis of the La-CdS/3D ZnIn2S4/Au@ZnO sensitization structure for detection of aminoterminal pro-brain natriuretic peptides (NT-proBNP). The Au@ZnO-modified electrode was first assembled with 3D ZnIn2S4, and then further deposited with lanthanum doped cadmium sulfide (La-CdS) via successive ionic layer adsorption and reaction strategy. The Au@ZnO has excellent photoelectric activity and electrical conductivity. The ZnIn2S4 with 3D architectures not only exhibit high photocurrent intensity under visible-light irradiation but also have large surface for the La-CdS deposition. Meanwhile, the La-CdS doped structure could depress the charge recombination, which effectively promotes separation of the generated electron-hole (e-/h+) pairs and consequently enhances the photocurrent conversion efficiency. The polydopamine (PDA) was used not only as a cross-linker reagent for the immobilization of the anti-NT-proBNP but also as an electron donor for promoting the photo-generated e-/h+ separation of the semiconductors. Under optimal conditions, the well-designed photoelectrochemical immunoassay exhibited a low detection limit of 0.32 pg mL-1 and a wide linear range from 0.8 pg mL-1 to 45 ng mL-1 for target NT-proBNP detection. Meanwhile, it also presented good reproducibility, specificity, and stability and might open a new promising strategy for the detection of other important tumor markers.

The label-free immunosensor based on rhodium@palladium nanodendrites/sulfo group functionalized multi-walled carbon nanotubes for the sensitive analysis of carcino embryonic antigen.

In this work, bimetallic core-shell rhodium@palladium nanodendrites (Rh@Pd NDs) loaded on sulfo group functionalized multi-walled carbon nanotubes (MWCNTs-SO3H) were combined to form Rh@Pd NDs/MWCNTs-SO3H nanocomposites. And the composites were used to construct a simple and label-free electrochemical immunosensor for carcino embryonic antigen (CEA) detection using differential pulse voltammetry (DPV). Rh@Pd NDs with dendritic nanostructure not only provide abundant catalytically active sites, but also increase the loading of antibody, which could improve the analytical performance and result in high sensitivity. In addition, the MWCNTs-SO3H could further enhance electrochemical properties due to the excellent conductivity, good solubility and high surface area. Taking advantages of both Rh@Pd NDs and MWCNTs-SO3H, the proposed immunosensor showed a broad linear range from 25 fg mL-1 to 100 ng mL-1 for CEA detection and a low detection limit of 8.3 fg mL-1 (signal-to-noise ratio of 3) under optimal experimental conditions. Moreover, the expected immunosensor exhibited good reproducibility and high sensitivity, which could achieve excellent analysis of CEA in human serum with satisfactory results. Therefore, the Rh@Pd NDs/MWCNTs-SO3H nanocomposites may be considered as a sensing platform for fabrication of simple, ultrasensitive and label-free electrochemical immunosensor.

New product identification in the sterol metabolism by an industrial strain Mycobacterium neoaurum NRRL B-3805.

Mycobacterium neoaurum NRRL B-3805 metabolizes sterols to produce androst-4-en-3,17-dione (AD) as the main product, and androsta-1,4-dien-3,17-dione, 9α-hydroxy androst-4-en-3,17-dione and 22-hydroxy-23,24-bisnorchol-4-en-3-one have been identified as by-products. In this study, a new by-product was isolated from the metabolites of sterols and identified as methyl 3-oxo-23,24-bisnorchol-4-en-22-oate (BNC methyl ester), which was proposed to be produced via the esterification of BNC catalyzed by an O-methyltransferase using S-adenosyl-l-methionine as the methyl group donor. These results might open a new dimension for improvement of the efficiency of microbial AD production by eliminating this by-product via genetic manipulation of the strain.

Ultrasensitive electrochemical immunosensor for quantitative detection of HBeAg using Au@Pd/MoS2@MWCNTs nanocomposite as enzyme-mimetic labels.

A sensitive sandwich-type electrochemical immunosensor for the detection of hepatitis B e antigen (HBeAg) was successfully developed based on the gold@palladium nanoparticles (Au@Pd NPs) loaded by molybdenum disulfide functionalized multiwalled carbon nanotubes (Au@Pd/MoS2@MWCNTs). The resultant nanocomposites not only possessed high specific surface area and good biocompatibility, but also exhibited excellent electro-catalytical property. Au NPs functionalized porous graphene oxide (p-GO@Au) were used as sensing platforms and primary antibodies carriers, which can accelerate the electron transfer and improve the load capacity of primary antibodies (Ab1), improving the sensitivity of the immunosensor. Under optimal conditions, the designed immunosensor could detect target HBeAg concentration in the range from 0.1pg/mL to 500pg/mL, with a low detection limit of 26fg/mL (S/N = 3) for HBeAg. Additionally, the designed immunosensor showed excellent specificity, good reproducibility and acceptable stability. The satisfactory results in analysis of human serum samples indicated that it had potential application in clinical monitoring of tumor markers.

Ultrasensitive electrochemical immunosensor for quantitative detection of SCCA using Co3O4@CeO2-Au@Pt nanocomposite as enzyme-mimetic labels.

Recently early diagnosis of squamous cell carcinoma antigen (SCCA) as a tumor maker of various cancers has increasingly attracted a lot of attention with heightening of incidence rate of cancer. The SCCA with low concentration in human serum should be diluted before detecting. Thus, an immunoassay with high sensitivity is significant for early detecting SCCA. Therefore, a nonenzymatic sandwich-type electrochemical immunosensor herein was conducted to quantitative detection of squamous cell carcinoma antigen (SCCA). The amino functionalized cobaltosic oxide @ ceric dioxide nanocubes with core-shell morphology were prepared to combine sea-urchin like gold @ platinum nanoparticles (Co3O4@CeO2-Au@Pt), and used as labels to conjugate with secondary antibodies for signal amplification. Due to the synergetic effect, excellent electrochemical property and superior auxiliary catalytic activity of Co3O4@CeO2-Au@Pt, high electrocatalytic current responses toward the reduction of hydrogen peroxide (H2O2) were achieved. Besides, the electrodeposited gold nanoparticles (D-Au NPs) which were modified on glassy carbon electrodes (GCE) were used as antibodies carriers and sensing platforms. With the well cooperation of Co3O4@CeO2-Au@Pt and D-Au NPs, a broad linear range from 100fg/mL to 80ng/mL with a low detection limit of 33 fg/mL for detecting SCCA was achieved. In addition, the immunosensor displayed with good reproducibility, high selectivity and stability. The results are satisfactory when the proposed method has been applied to analyze human serum samples, indicating that the potential application is promising in clinical monitoring of tumor markers.

A novel sandwich-type electrochemical immunosensor for PSA detection based on PtCu bimetallic hybrid (2D/2D) rGO/g-C3N4.

In this work, a sensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of prostate-specific antigen (PSA) by amperometric i-t. The Au loaded on thionine functionalized graphene oxide (Au@Th/GO) was used as a platform to immobilize primary antibodies (Ab1) and accelerate the electron transfer on the electrode interface. PtCu bimetallic hybrid were loaded on 2D/2D reduced graphene oxide/graphitic carbon nitride (PtCu@rGO/g-C3N4) with large surface area and biocompatibility, which were employed as labels for combining secondary antibodies (Ab2) and amplifying signals to improve the sensitivity of the designed immunosensor which attributes to its good activity for the reduction of hydrogen peroxide (H2O2). Under optimal conditions, the designed immunosensor exhibited a linear concentration range from 50fg/mL to 40ng/mL, with a low detection limit of 16.6fg/mL (S/N=3) for PSA. Additionally, the designed immunosensor showed acceptable selectivity, reproducibility and stability. The satisfactory results in analyze human serum samples indicated potential application promising in clinical monitoring of tumor markers.

Ultrasensitive amperometric immunosensor for PSA detection based on Cu2O@CeO2-Au nanocomposites as integrated triple signal amplification strategy.

In this work, a novel label-free electrochemical immunosensor was developed for the quantitative detection of prostate specific antigen (PSA). To this end, the amino functionalized cuprous oxide @ ceric dioxide (Cu2O@CeO2-NH2) core-shell nanocomposites were prepared to bond gold nanoparticles (Au NPs) by constructing stable Au-N bond between Au NPs and -NH2. Because the synergetic effect presents in Cu2O@CeO2 core-shell loaded with Au NPs (Cu2O@CeO2-Au), it shows better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) than single Cu2O, Au NPs and Cu2O@CeO2. Featured by large specific surface area, good biocompatibility and good electrochemical properties which can greatly improve the electronic transmission rate, Cu2O@CeO2-Au was used as transducing materials to achieve efficiently capture antibodies and triple signal amplification of the proposed immunosensor. Under the optimal conditions, the proposed immunosensor exhibited a wide linear range from 0.1pg/mL to 100ng/mL with a low detection limit of 0.03pg/mL (S/N=3). Furthermore, the proposed label-free immunosensor has been used to determine PSA in human serum with satisfactory results. Meanwhile, it displayed good reproducibility, acceptable selectivity, and long-term stability, which had promising application in bioassay analysis.

Effect of smokeless tobacco products on human oral bacteria growth and viability.

To evaluate the toxicity of smokeless tobacco products (STPs) on oral bacteria, seven smokeless tobacco aqueous extracts (STAEs) from major brands of STPs and three tobacco-specific N-nitrosamines (TSNAs) were used in a growth and viability test against 38 oral bacterial species or subspecies. All seven STAEs showed concentration-dependent effects on the growth and viability of tested oral bacteria under anaerobic culture conditions, although there were strain-to-strain variations. In the presence of 1 mg/ml STAEs, the growth of 4 strains decreased over 0.32-2.14 log10 fold, while 14 strains demonstrated enhanced growth of 0.3-1.76 log10 fold, and the growth of 21 strains was not significantly affected. In the presence of 10 mg/ml STAEs, the growth of 17 strains was inhibited 0.3-2.11 log10 fold, 18 strains showed enhanced growth of 0.3-0.97 log10 fold, and 4 strains were not significantly affected. In the presence of 50 mg/ml STAEs, the growth of 32 strains was inhibited 0.3-2.96 log10 fold, 8 strains showed enhanced growth of 0.3-1.0 log10 fold, and 2 strains were not significantly affected. All seven STAEs could promote the growth of 4 bacterial strains, including Eubacterium nodatum, Peptostreptococcus micros, Streptococcus anginosus, and Streptococcus constellatus. Exposure to STAEs modulated the viability of some bacterial strains, with 21.1-66.5% decrease for 4 strains at 1 mg/ml, 20.3-85.7% decrease for 10 strains at 10 mg/ml, 20.0-93.3% decrease for 27 strains at 50 mg/ml, and no significant effect for 11 strains at up to 50 mg/ml. STAEs from snuffs inhibited more tested bacterial strains than those from snus indicating that the snuffs may be more toxic to the oral bacteria than snus. For TSNAs, cell growth and viability of 34 tested strains were not significantly affected at up to 100 µg/ml; while the growth of P. micros was enhanced 0.31-0.54 log10 fold; the growth of Veillonella parvula was repressed 0.33-0.36 log10 fold; and the cell viabilities of 2 strains decreased 56.6-69.9%. The results demonstrate that STAEs affected the growth of some types of oral bacteria, which may affect the healthy ecological balance of oral bacteria in humans. On the other hand, TSNAs did not significantly affect the growth of the oral bacteria.

Toxicological significance of azo dye metabolism by human intestinal microbiota.

Approximately 0.7 million tons of azo dyes are synthesized each year. Azo dyes are composed of one or more R1-N=N-R2 linkages. Studies have shown that both mammalian and microbial azoreductases cleave the azo bonds of the dyes to form compounds that are potentially genotoxic. The human gastrointestinal tract harbors a diverse microbiota comprised of at least several thousand species. Both water-soluble and water-insoluble azo dyes can be reduced by intestinal bacteria. Some of the metabolites produced by intestinal microbiota have been shown to be carcinogenic to humans although the parent azo dyes may not be classified as being carcinogenic. Azoreductase activity is commonly found in intestinal bacteria. Three types of azoreductases have been characterized in bacteria. They are flavin dependent NADH preferred azoreductase, flavin dependent NADPH preferred azoreductase, and flavin free NADPH preferred azoreductase. This review highlights how azo dyes are metabolized by intestinal bacteria, mechanisms of azo reduction, and the potential contribution in the carcinogenesis/mutagenesis of the reduction of the azo dyes by intestinal microbiota.