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1.
Psychol Health Med ; 29(7): 1265-1280, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38166576

ABSTRACT

This study aimed to examine the association between occupational burnout and psychological symptoms among Chinese medical staff, assuming social support to play a moderating role in the aforementioned relationship. The survey was conducted online from May 1 to June 28, 2022, and the questionnaires were distributed and retrieved through a web-based platform. The final sample was comprised of 1461 Chinese medical staff in this cross-sectional study. Several multiple linear regressions were performed to analyze the data. After controlling for potential confounding factors, all three dimensions of occupational burnout were associated with poorer psychological symptoms. Emotional exhaustion (ß = 0.33; 95% confidence interval [CI], 1.018, 1.479) had the strongest association with psychological symptoms, followed by depersonalization and diminished personal accomplishment. Moreover, medical staff with higher levels of friend support (ß = -0.11; 95% CI, -4.063, -0.573) and significant other support (ß = -0.10; 95% CI, -3.965, -0.168) were less likely to suffer from psychological symptoms when faced with occupational burnout. The results suggested that interventions aimed at lessening occupational burnout and boosting social support can be an effective way to promote the psychological health of medical staff.


Subject(s)
Burnout, Professional , Social Support , Humans , Burnout, Professional/psychology , Burnout, Professional/epidemiology , Male , Female , Adult , China/epidemiology , Cross-Sectional Studies , Middle Aged , Surveys and Questionnaires , Depersonalization/psychology , Medical Staff/psychology , East Asian People
2.
Food Chem ; 404(Pt A): 134183, 2023 Mar 15.
Article in English | MEDLINE | ID: mdl-36240563

ABSTRACT

Based on graphite-like carbon nitride (g-CN) nanocomposites coupled with aptamer, a regenerable electrochemiluminescence (ECL) biosensor is developed for the quantitative detection of aflatoxin B1 (AFB1). In the existence of AFB1, the structure of the aptamer changed into a loop, and the original ECL intensity was reduced owing to the enhancement of luminescence quenching between the ferrocene modified at the end of the aptamer and the luminescent substrate g-CN. Moreover, AFB1 with oxidation state could also react with high energy state g-CN, leading to further reduction of the electrochemiluminescence signal. At optimum conditions, ECL intensity was decreased in linearity with an AFB1 concentration range from 0.005 ng/mL to 10 ng/mL, and the minimum detectable concentration was down to 0.005 ng/mL, which realized trace detection demand with high sensitivity. It was selective for AFB1 and its performance had been verified on rice samples, which indicated a promising applying prospect of non-enzymatic electrochemiluminescence AFB1 detection.


Subject(s)
Biosensing Techniques , Graphite , Graphite/chemistry , Luminescence , Biosensing Techniques/methods , Aflatoxin B1/analysis , Limit of Detection , Luminescent Measurements/methods , Electrochemical Techniques
3.
J Am Chem Soc ; 144(51): 23396-23404, 2022 Dec 28.
Article in English | MEDLINE | ID: mdl-36520048

ABSTRACT

Covalent organic frameworks (COFs) with porphyrins as structural units are a new kind of porous organic polymers, which have a regular and ordered structure, abundant porosity, and good stability. In the past, the construction of porphyrin COFs was generally synthesized by routes such as a Schiff base reaction. Here, we report a new COF structure by linking the porphyrin with the triazine ring. Using a cyano group-terminated porphyrin as a structural unit precursor, a new triazine-porphyrin hyperconjugated COF (TA-Por-sp2-COF) was constructed through the cyano group's self-polymerization. The extension of porphyrin units in two directions that stemmed from the cyano group at para-positions accounts for the establishment of a highly ordered two-dimensional topological structure. Attributing to the collaboration of electron-donating and withdrawing blocks for photo-induced carrier separation and adequate porosity for mass diffusion, this hyperconjugated system showed high photocatalytic performance in organic reactions such as the aerobic coupling reaction of benzylamine and thioanisole selective oxidation.

4.
RSC Adv ; 12(37): 24311-24318, 2022 Aug 22.
Article in English | MEDLINE | ID: mdl-36128522

ABSTRACT

In the exploration of synthesizing graphitic carbon nitride (g-C3N4), the existence of secondary anime bridging units shows the incompleteness of related theories. Thus, taking the thermal synthesis of melamine as an example, this work finds a possible reaction path with Density Functional Theory (DFT) for forming melem during the thermal synthesis of g-C3N4. Combined with transition state theory (TST), it indicates that the formation of melem results from the condensation of melamine and isomerization of melam. Meanwhile, the weak signal near 2135 cm-1 in the Fourier Transform Infrared Spectra (FTIR) corresponds to the vibration of carbodi-imines (-N[double bond, length as m-dash]C[double bond, length as m-dash]N-), which further proves the proposed reaction path. Thus, this work can explain the formation of g-C3N4 and its monomer, which may contribute to the successful formation of ideal g-C3N4 in the future.

5.
Nanoscale ; 14(37): 13731-13739, 2022 Sep 29.
Article in English | MEDLINE | ID: mdl-36097975

ABSTRACT

Solar-driven interfacial evaporation is a promising technology for water recycling and purification. A sustainable solar evaporation material should have not only high photothermal conversion efficiency, but also an ecofriendly fabrication process as well as pollutant degradation and sterilization properties. We present in this work a solar evaporator based on graphitic carbon nitride (g-C3N4) and copper phthalocyanine (CUPC) composites with typical type-I heterojunctions. Superhydrophilic three-dimensional macroporous g-C3N4 was obtained by self-assembly of precursors in aqueous solution followed by thermal polycondensation. By adding various weight ratios (0.15%, 1.5% and 7.5%) of CUPC, the composites exhibited a strong absorption in the region of red and infrared light. The CUPC-CN 7.5% composite achieved a photothermal conversion efficiency of 98.5% in nanofluids with an interfacial solar evaporation efficiency of 93.6% for artificial sea water and 98.7% for deionized water, which are among the highest reported to date. Besides, the composite materials demonstrated superior water purification capabilities by decomposing dye molecules and E. coli bacteria in aqueous solution. Our work established a novel approach for the development of multifunctional interfacial evaporators based on macroporous organic semiconductor heterostructures.

6.
Front Genet ; 13: 872253, 2022.
Article in English | MEDLINE | ID: mdl-35547257

ABSTRACT

Background: The aim of this study was to identify a panel of candidate autoantibodies against tumor-associated antigens in the detection of osteosarcoma (OS) so as to provide a theoretical basis for constructing a non-invasive serological diagnosis method in early immunodiagnosis of OS. Methods: The serological proteome analysis (SERPA) approach was used to select candidate anti-TAA autoantibodies. Then, indirect enzyme-linked immunosorbent assay (ELISA) was used to verify the expression levels of eight candidate autoantibodies in the serum of 51 OS cases, 28 osteochondroma (OC), and 51 normal human sera (NHS). The rank-sum test was used to compare the content of eight autoantibodies in the sera of three groups. The diagnostic value of each indicator for OS was analyzed by an ROC curve. Differential autoantibodies between OS and NHS were screened. Then, a binary logistic regression model was used to establish a prediction logistical regression model. Results: Through ELISA, the expression levels of seven autoantibodies (ENO1, GAPDH, HSP27, HSP60, PDLIM1, STMN1, and TPI1) in OS patients were identified higher than those in healthy patients (p < 0.05). By establishing a binary logistic regression predictive model, the optimal panel including three anti-TAAs (ENO1, GAPDH, and TPI1) autoantibodies was screened out. The sensitivity, specificity, Youden index, accuracy, and AUC of diagnosis of OS were 70.59%, 86.27%, 0.5686, 78.43%, and 0.798, respectively. Conclusion: The results proved that through establishing a predictive model, an optimal panel of autoantibodies could help detect OS from OC or NHS at an early stage, which could be used as a promising and powerful tool in clinical practice.

7.
J Healthc Eng ; 2022: 8941922, 2022.
Article in English | MEDLINE | ID: mdl-35356611

ABSTRACT

Objective: To explore the current situation and influencing factors of traditional Chinese medicine (TCM) nursing clinic in Henan Province. A self-made questionnaire was made and entered into the questionnaire star. In August 2020, through "the snowball sampling method," the nursing branch of Henan Society of Traditional Chinese Medicine was used to calculate the sample size that would be further used for this study. Results: Of the 370 medical institutions in 17 district-level cities in our province, 47 have set up TCM nursing clinics, accounting for 12.70%. From the perspective of regional distribution, there are 14 TCM nursing clinics in Zhengzhou, 8 in Luoyang, 6 in Kaifeng, 4 in Shangqiu, 3 in Jiyuan, and 3 in Zhoukou. The number of TCM nursing clinics in Jiaozuo City, Xinxiang City, Anyang City, Hebi City, Puyang City, Zhumadian City, and Nanyang City is relatively small, and there are no TCM nursing clinics in Pingdingshan City, Sanmenxia City, and Xinyang City. Among the 47 medical institutions offering TCM nursing clinics, there are 38 TCM hospitals, 5 integrated traditional Chinese and Western medicine hospitals, 3 Western medicine hospitals, and 1 ethnic medicine hospital. Among them, 31 medical institutions are tertiary care hospitals and 16 are secondary care hospitals. First-class and undetermined medical institutions do not set up TCM nursing clinics. (1) Management mode: among the 47 medical institutions, 26 medical institutions have separate nursing units, which are managed by the nursing department head nurse, and 13 medical institutions are managed by the director head nurse of the department. (2) Performance management: of the 47 medical institutions that set up TCM nursing clinics, 18 adopted independent accounting, 21 adopted secondary distribution of departmental performance, and 7 adopted average awards and other methods. (3) The process of seeing a doctor: there are three kinds of medical procedures: 124 medical institutions are treated by TCM nursing outpatients by hanging the consultation number of doctors in various departments. 210 medical institutions are treated by traditional Chinese medicine nursing outpatient nurses by hanging the consultation number of traditional Chinese medicine nursing outpatient doctors. Thirty-five medical institutions are retreated by hanging the number of nurses in the nursing clinic of TCM. (4) Allocation of human resources: in the survey of the total number of nurses in TCM nursing clinics in 74 medical institutions, the largest number of nurses was 46 in one of the TCM nursing clinics. In terms of personnel qualification requirements, 43 medical institutions put forward requirements for nurses' qualifications. Among them, 39 medical institutions have requirements for nurses' professional titles, 38 medical institutions have requirements for nurses working years, and 22 medical institutions have more specific requirements for nurses. For example, nurses are required to be the backbone of TCM nursing that includes specialist nurses, nurses who graduated from TCM colleges, and nurses who have obtained hospital assessment and certification. In terms of working years, 87.96% of medical institutions require nursing service of more than 5 years. The average number of TCM nursing technical projects offered by 47 medical institutions is about 10, a maximum of 34 and a minimum of 1. The commonly carried out TCM nursing techniques include scraping, auricular point pressing, cupping, moxibustion, and ear tip bloodletting, and among all of them, scraping technology is most important and 40 medical institutions offer this technology, followed by auricular point pressing technique, cupping, and moxibustion. Conclusion: The construction of TCM nursing clinics in Henan Province has initially formed a scale, and all kinds of medical institutions at all levels should further strengthen the construction of TCM nursing clinics in all other provinces.


Subject(s)
Nurses , Physicians , Health Occupations , Humans , Medicine, Chinese Traditional , Surveys and Questionnaires
8.
ACS Appl Bio Mater ; 4(10): 7587-7594, 2021 10 18.
Article in English | MEDLINE | ID: mdl-35006694

ABSTRACT

In this work, the photocatalytic and photothermal effects of carbon-ring-doped graphitic carbon nitride materials against bacteria were systematically studied in a dispersed solution and on a membrane. C-doped graphitic carbon nitride materials C-CN 0.15, 1.5, and 7.5 were synthesized by mixing urea precursor with 0.15, 1.5, and 7.5 wt % glucose. With the increase in the doping level, the photothermal effect was clearly enhanced while the generation of reactive oxygen species (ROS) was slightly inhibited. With exposure to irradiation under a 100 mW cm-2 Xeon lamp with a cutoff filter (λ ≥ 420 nm), the ROS concentration of C-CN 1.5 increased 30% in the dispersed solution and its temperature increased about 10 °C in the dispersed solution and on the membrane compared to that of pristine carbon nitride. As a result, the bactericidal activity of C-CN 1.5 was improved by an order of magnitude in the dispersed solution and more than 2 orders of magnitude on the membrane immersed in a solution at 40 °C. To investigate the fundamental light absorption process on the membrane, an optical model using the finite-difference time-domain method was developed based on the topography of the membrane. The simulation results may explain that although C-CN produces more ROS in a solution; however, with a larger extinction coefficient, the power absorption is lower near the surface of the membrane. The ROS production is therefore inhibited and the bactericidal activity is dominated by the photothermal effect. Our experimental and simulation results provide a basis for designing high-performance photoactive disinfection materials and surfaces.


Subject(s)
Disinfection , Light , Bacteria , Disinfection/methods , Graphite , Nitrogen Compounds , Reactive Oxygen Species
9.
J Mater Chem B ; 8(5): 1008-1016, 2020 02 07.
Article in English | MEDLINE | ID: mdl-31930260

ABSTRACT

Hybrid metal compounds have been paid increasing attention for the development of electroanalysis materials due to the specific collaboration interaction and synergy effect of metal elements. Herein, a series of ultrathin Ni/Co bimetallic metal-organic-framework nanosheets (UMOFNs) with different metal ratios were investigated as high-performance electroanalysis materials for non-enzymatic glucose electrochemical sensing. The synergistic effect between Ni/Co endowed UMOFNs with not only the unique electrochemical behavior that prompts the sensing-related electrochemical oxidation at a low applied potential, but also the enhanced affinity to glucose; also, they facilitated the electron transfer involving the analyte. The UMOFN composite with an elaborately adjusted Co/Ni ratio exhibits an extremely outstanding glucose sensing performance, including high sensitivity (2086.7 µA mM-1 cm-2), wide linear range (0.1 µM-1.4 mM), low detection limit (0.047 µM), and excellent selectivity. It can also be used for the detection of glucose in actual human serum samples with an accuracy of 90.1%, demonstrating a good application prospect of the non-enzymatic electrochemical glucose detection.


Subject(s)
Biosensing Techniques , Electrochemical Techniques , Glucose/analysis , Metal-Organic Frameworks/chemistry , Nanoparticles/chemistry , Cobalt/chemistry , Density Functional Theory , Electrodes , Humans , Materials Testing , Metal-Organic Frameworks/chemical synthesis , Nickel/chemistry , Particle Size , Surface Properties
10.
ACS Appl Bio Mater ; 3(4): 2255-2262, 2020 Apr 20.
Article in English | MEDLINE | ID: mdl-35025277

ABSTRACT

With the rise of bacterial infections and antimicrobial resistance, it is important to develop environmentally friendly functional materials and surfaces with efficient bactericidal activity. In this work, nanostructured graphitic carbon nitride (g-C3N4) surfaces were fabricated by electrophoresis deposition of mesoporous g-C3N4 materials. Efficient bactericidal performance was achieved through the synergistic biophysical interaction of bacterial cells with the nanotopographies and visible light active photocatalytic properties. The nanotopographies of g-C3N4 surfaces demonstrated a "contact-killing" efficiency of >90% against Pseudomonas aeruginosa and >80% against Staphylococcus aureus cells. The number of surviving bacteria on the surfaces further decreased remarkably upon illumination using visible light generated by a light-emitting diode lamp with an irradiation intensity of 12.4 mW cm-2. In total, the number of viable bacteria was reduced by approximately 3 orders of magnitude for P. aeruginosa and 2 orders of magnitude for S. aureus. Our experimental findings provide potential prospects for developing highly efficient photocatalytic bactericidal surfaces.

11.
ACS Omega ; 3(6): 6456-6464, 2018 Jun 30.
Article in English | MEDLINE | ID: mdl-30023948

ABSTRACT

Hospital-acquired infections can cause serious complications and are a severe problem because of the increased emergence of antibiotic-resistant bacteria. Biophysical modification of the material surfaces to prevent or reduce bacteria adhesion is an attractive alternative to antibiotic treatment. Since stainless steel is a widely used material for implants and in hospital settings, in this work, we used stainless steel to investigate the effect of the material surface topographies on bacterial adhesion and early biofilm formation. Stainless steel samples with different surface roughnesses Rq in a range of 217.9-56.6 nm (Ra in a range of 172.5-45.2 nm) were fabricated via electropolishing and compared for adhesion of bacterial pathogens Pseudomonas aeruginosa and Staphylococcus aureus. It was found that the number of viable cells on the untreated rough surface was at least 10-fold lower than those on the electropolished surfaces after 4 h of incubation time for P. aeruginosa and 15-fold lower for S. aureus. Fluorescence images and scanning electron microscopy images revealed that the bacterial cells tend to adhere individually as single cells on untreated rough surfaces. In contrast, clusters of the bacterial cells (microcolonies) were observed on electropolished smooth surfaces. Our study demonstrates that nanoscale surface roughness can play an important role in restraining bacterial adhesion and formation of microcolonies.

12.
J Nanobiotechnology ; 16(1): 20, 2018 Feb 28.
Article in English | MEDLINE | ID: mdl-29490703

ABSTRACT

BACKGROUND: Due to the increased emergence of antimicrobial resistance, alternatives to minimize the usage of antibiotics become attractive solutions. Biophysical manipulation of material surface topography to prevent bacterial adhesion is one promising approach. To this end, it is essential to understand the relationship between surface topographical features and bactericidal properties in order to develop antibacterial surfaces. RESULTS: In this work a systematic study of topographical effects on bactericidal activity of nanostructured surfaces is presented. Nanostructured Ormostamp polymer surfaces are fabricated by nano-replication technology using nanoporous templates resulting in 80-nm diameter nanopillars. Six Ormostamp surfaces with nanopillar arrays of various nanopillar densities and heights are obtained by modifying the nanoporous template. The surface roughness ranges from 3.1 to 39.1 nm for the different pillar area parameters. A Gram-positive bacterium, Staphylococcus aureus, is used as the model bacterial strain. An average pillar density at ~ 40 pillars µm-2 with surface roughness of 39.1 nm possesses the highest bactericidal efficiency being close to 100% compared with 20% of the flat control samples. High density structures at ~ 70 pillars µm-2 and low density structures at < 20 pillars µm-2 with surface roughness smaller than 20 nm reduce the bactericidal efficiency to almost the level of the control samples. CONCLUSION: The results obtained here suggests that the topographical effects including pillar density and pillar height inhomogeneity may have significant impacts on adhering pattern and stretching degree of bacterial cell membrane. A biophysical model is prepared to interpret the morphological changes of bacteria on these nanostructures.


Subject(s)
Anti-Bacterial Agents/chemistry , Nanostructures/chemistry , Polymers/chemistry , Staphylococcus aureus/physiology , Bacterial Adhesion , Biocompatible Materials/chemistry , Humans , Microbial Viability , Nanostructures/ultrastructure , Porosity , Staphylococcal Infections/prevention & control , Staphylococcus aureus/cytology , Surface Properties
13.
Analyst ; 143(6): 1462-1467, 2018 Mar 12.
Article in English | MEDLINE | ID: mdl-29469161

ABSTRACT

This work presents a novel rapid and sensitive label-free electrochemical method for the detection of bacteria on surface nanostructures. A simple electrochemical deposition and calcination method is employed to prepare different gold nanostructures on FTO substrate. The sensor based on nanostructure gold exhibits excellent linear relation between E. coli DH5α bacteria and the changes of ΔRct, especially FTO-GEDC-D30, with a correction coefficient R2 = 0.998. Both the spectrophotometric (OD600 methods) and fluorescence-staining methods also verified the reliability of electrochemical impedance spectroscopy (EIS) methods for evaluating the antibacterial activity of the gold nanostructure.


Subject(s)
Biosensing Techniques , Electrochemical Techniques , Escherichia coli/isolation & purification , Gold , Nanostructures , Dielectric Spectroscopy , Electrodes , Reproducibility of Results
14.
Adv Mater ; 30(9)2018 Mar.
Article in English | MEDLINE | ID: mdl-29333629

ABSTRACT

Reinforcing the carrier separation is the key issue to maximize the photocatalytic hydrogen evolution (PHE) efficiency of graphitic carbon nitride (g-C3 N4 ). By a surface engineering of gradual doping of graphited carbon rings within g-C3 N4 , suitable energy band structures and built-in electric fields are established. Photoinduced electrons and holes are impelled into diverse directions, leading to a 21-fold improvement in the PHE rate.

15.
ACS Appl Mater Interfaces ; 9(11): 9496-9505, 2017 Mar 22.
Article in English | MEDLINE | ID: mdl-28244327

ABSTRACT

Permeable membranes are indispensable for in vitro epithelial barrier models. However, currently available polymer-based membranes are low in porosity and relatively thick, resulting in a limited permeability and unrealistic culture conditions. In this study, we developed an ultrathin, nanoporous alumina membrane as novel cell culture interface for vertebrate cells, with focus on the rainbow trout (Onchorynchus mykiss) intestinal cell line RTgutGC. The new type of membrane is framed in a silicon chip for physical support and has a thickness of only 1 µm, with a porosity of 15% and homogeneous nanopores (Ø = 73 ± 21 nm). Permeability rates for small molecules, namely lucifer yellow, dextran 40, and bovine serum albumin, exceeded those of standard polyethylene terephthalate (PET) membranes by up to 27 fold. With the final goal to establish a representative model of the fish intestine for environmental toxicology, we engineered a simple culture setup, capable of testing the cellular response toward chemical exposure. Herein, cells were cultured in a monolayer on the alumina membranes and formed a polarized epithelium with apical expression of the tight junction protein ZO-1 within 14 days. Impedance spectroscopy, a noninvasive and real time electrical measurement, was used to determine cellular resistance during epithelial layer formation and chemical exposure to evaluate barrier functionality. Resistance values during epithelial development revealed different stages of epithelial maturity and were comparable with the in vivo situation. During chemical exposure, cellular resistance changed immediately when barrier tightness or cell viability was affected. Thus, our study demonstrates nanoporous alumina membranes as promising novel interface for alternative in vitro approaches, capable of allowing cell culture in a physiologically realistic manner and enabling high quality microscopy and sensitive measurement of cellular resistance.


Subject(s)
Epithelial Cells , Aluminum Oxide , Animals , Cell Culture Techniques , Intestines , Oncorhynchus mykiss
16.
Talanta ; 159: 194-199, 2016 Oct 01.
Article in English | MEDLINE | ID: mdl-27474298

ABSTRACT

In this article, a fast and sensitive nonenzymatic glucose sensor is reported utilizing a glassy carbon electrode modified by synthesizing nanocomposites of nickel nanoparticle-attapulgite-reduced graphene oxide (Ni NPs/ATP/RGO). A facile one-step electrochemical co-deposition approach is adopted to synthesize Ni NPs-ATP-RGO nanocomposites via electrochemical reduction of mixed precursor solution containing graphene oxide (GO), attapulgite (ATP) and nickel cations (Ni(2+)) at the cathode potentials. This strategy results in simultaneous depositions of ATP, cathodic reduction of Ni(2+) into nickel nanoparticles under acidic conditions, and in situ reduction of GO. The as-prepared NiNPs/ATP/RGO-based glucose sensor exhibits outstanding performance for enzymeless glucose sensing with sensitivity (1414.4 µAmM(-1)cm(-2)), linear range (1-710µM) and detection limit (0.37µM). What is more, the sensor has excellent stability and selectivity against common interferences in real sample.


Subject(s)
Carbon/chemistry , Electrochemical Techniques/instrumentation , Electrochemical Techniques/methods , Electrodes , Glucose/analysis , Nickel/chemistry , Oxides/chemistry , Graphite/chemistry , Magnesium Compounds/chemistry , Nanoparticles/chemistry , Silicon Compounds/chemistry
17.
Analyst ; 141(15): 4713-8, 2016 Aug 07.
Article in English | MEDLINE | ID: mdl-27277544

ABSTRACT

A highly sensitive and selective tumor cell sensor based on partially oxidized graphene (POG) and folate acid (FA) composite was constructed. The POG was prepared through a modified Hummers method and characterized by means of Raman spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, atomic force microscopy and transmission electron microscopy. The as-prepared POG exhibited the advantages of high electrochemical activity and a good capacity of linking amine derivatives. Using a facile one step reaction, the FA-modified POG was endowed with a more sensitive response to folate-expressing tumor cells than those sensors constructed by the two-step reaction, as well as high selectivity, good reproducibility and long-term stability.


Subject(s)
Biosensing Techniques , Folate Receptor 2/chemistry , Folic Acid/chemistry , Graphite , Animals , CHO Cells , Cricetulus , HeLa Cells , Humans , Microscopy, Electron, Transmission , Oxidation-Reduction , Reproducibility of Results
18.
Nanoscale ; 8(5): 2620-5, 2016 Feb 07.
Article in English | MEDLINE | ID: mdl-26648134

ABSTRACT

We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all the Au nanostructures, regardless their shapes, exhibited similar excellent antibacterial properties. A comparison of live cells attached to nanotopographic surfaces showed that the number of live S. aureus cells was <1% of that from flat and rough reference surfaces. Our micro/nanofabrication process is a scalable approach based on cost-efficient self-organization and provides potential for further developing functional surfaces to study the behavior of microbes on nanoscale topographies.


Subject(s)
Anti-Bacterial Agents/chemistry , Gold/chemistry , Nanostructures/chemistry , Anti-Bacterial Agents/pharmacology , Electroplating , Methicillin-Resistant Staphylococcus aureus/drug effects , Methicillin-Resistant Staphylococcus aureus/growth & development , Nanostructures/toxicity , Staphylococcus aureus/drug effects , Staphylococcus aureus/growth & development , Surface Properties
19.
Soft Matter ; 11(20): 4081-90, 2015 May 28.
Article in English | MEDLINE | ID: mdl-25921409

ABSTRACT

We investigate ionic partition of negatively charged molecular probes into also negatively charged, covalently crosslinked alginate hydrogels. The aim is to delimit the domain of validity of the major nanoelectrostatic models, and in particular to assess the influence of hydrogel chain mobility on ionic partition. We find that the widely used Gibbs-Donnan model greatly overestimates exclusion of the co-ion probes used. For low molecular weight probes, a much better fit is obtained by taking into account the electrostatics in the nanometric gel pores by means of the Poisson-Boltzmann framework; the fit is improved slightly when taking into account alginate chain mobility. For high molecular weight probes, we find it essential to take into account local gel deformation due to electrostatic repulsion between the flexible gel strands and the probe. This is achieved by combining Poisson-Boltzmann simulations with heterogeneous pore size distribution given by the Ogston model, or more simply and precisely, by applying a semi-empirical scaling law involving the ratio between Debye length and pore size.


Subject(s)
Hydrogels/chemistry , Lab-On-A-Chip Devices , Nanotechnology/instrumentation , Alginates/chemistry , Glucuronic Acid/chemistry , Hexuronic Acids/chemistry , Potassium Chloride/chemistry , Static Electricity
20.
Nanoscale ; 4(18): 5718-23, 2012 Sep 21.
Article in English | MEDLINE | ID: mdl-22885910

ABSTRACT

Active control of ion transport plays important roles in chemical and biological analytical processes. Nanofluidic systems hold the promise for such control through electrostatic interaction between ions and channel surfaces. Most existing experiments rely on planar geometry where the nanochannels are generally very long and shallow with large aspect ratios. Based on this configuration the concepts of nanofluidic gating and rectification have been successfully demonstrated. However, device minimization and throughput scaling remain significant challenges. We report here an innovative and facile realization of hetero-structured Al(2)O(3)/SiO(2) (Si) nanopore array membranes by using pattern transfer of self-organized nanopore structures of anodic aluminum oxide (AAO). Thanks to the opposite surface charge states of Al(2)O(3) (positive) and SiO(2) (negative), the membrane exhibits clear rectification of ion current in electrolyte solutions with very low aspect ratios compared to previous approaches. Our hetero-structured nanopore arrays provide a valuable platform for high throughput applications such as molecular separation, chemical processors and energy conversion.

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