Nanowires of silver-polyaniline nanocomposite synthesized via in situ polymerization and its novel functionality as an antibacterial agent

Fabrication of a graphene@Ni foam-supported silver nanoplates-PANI 3D architecture electrode for enzyme-free glucose sensing

Reliable and cost-effective glucose sensors are in rising demand among diabetes patients. The combination of metals and conducting polymers creates a robust electrocatalyst for glucose oxidation, offering enzyme-free, high stability, and sensitivity with outstanding electrochemical results. Herein, graphene is grown on nickel foam by chemical vapor deposition to make a graphene@nickel foam scaffold (G@NF), on which silver nanoplates-polyaniline (Ag-PANI) 3D architecture is developed by sonication-assisted co-electrodeposition. The resulting binder-free 3D Ag-PANI/G@NF electrode was highly porous, as characterized by x-ray photoelectron spectroscopy, Field emission scanning electron microscope, x-ray diffractometer, FTIR, and Raman spectroscopy. The binder-free 3D Ag-PANI/G@NF electrode exhibits remarkable electrochemical efficiency with a superior electrochemical active surface area. The amperometric analysis provides excellent anti-interference performance, a low limit of deduction (0.1 nM), robust sensitivity (1.7 × 1013µA mM-1cm-2), and a good response time. Moreover, the Ag-PANI/G@NF enzyme-free sensor is utilized to observe glucose levels in human blood serums and exhibits excellent potential to become a reliable clinical glucose sensor.

Synthesis and characterization of antimicrobial colloidal polyanilines

The potential application of colloidal polyaniline (PANI) as an antimicrobial is limited by challenges related to solubility in common organic solvents, scalability, and antimicrobial potency. To address these limitations, we introduced a functionalized PANI (fPANI) with carboxyl groups through the polymerisation of aniline and 3-aminobenzoic acid in a 1:1 molar ratio. fPANI is more soluble than PANI which was determined using a qualitative study. We further enhanced the solubility and antimicrobial activity of fPANI by incorporating Ag nanoparticles onto the synthesized fPANI colloid via direct addition of 10 mM AgNO3. The improved solubility can be attributed to an approximately 3-fold reduction in size of particles. Mean particle sizes are measured at 1322 nm for fPANI colloid and 473 nm for fPANI-Ag colloid, showing a high dispersion and deagglomeration effect from Ag nanoparticles. Antimicrobial tests demonstrated that fPANI-Ag colloids exhibited superior potency against Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli, and Bacteriophage PhiX 174 when compared to fPANI alone. The minimum bactericidal concentration (MBC) and minimum virucidal concentration (MVC) values were halved for fPANI-Ag compared to fPANI colloid and attributed to the combination of Ag nanoparticles with the fPANI polymer. The antimicrobial fPANI-Ag colloid presented in this study shows promising results, and further exploration into scale-up can be pursued for potential biomedical applications.

Anticancer potential of poly(2-aminobenzoic acid)-blend-Aloe vera against the human breast cancer cell line MDA-MB-231

Breast cancer in women is amongst the most significant concerns from time immemorial in the field of oncology. This study proposes an anticancerous polymeric material based on an electroactive substituted polyaniline blend, poly(2-aminobenzoic acid)-blend-Aloe vera (PABA/AV) synthesized by the emulsion polymerization method. The structural, thermal, and morphological characteristics determined using FT-IR and UV-Visible Spectroscopy, XRD, TGA, DTA, and SEM-EDX validated the thermally stable, semi-crystalline, emeraldine salt structure. The material is semi-conducting, and the electrical conductivity measured is 1.86 × 10−3 S/cm. It shows bactericidal efficacy against Enterococcus faecalis at a minimum inhibitory and minimum bactericidal concentration of 50 μg/mL. The radical cations in the emeraldine polymer chain reduce the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and exhibit a significant % of DPPH scavenging (89.85%) at 20 μL. The polymer blend is active against the human breast cancer cell line MDA-MB-231 and causes 78.65% cytotoxicity at a concentration of 125 μg/mL. The synergistic effect of the ancient healing Aloe vera plant and the electroactive biocompatible poly(2-aminobenzoic acid) certainly opens up new developments in the field of cancer therapy.

Design, synthesis, and characterization of novel eco-friendly chitosan-AgIO3 bionanocomposite and study its antibacterial activity

This work reports a facile and green approach to preparing AgIO₃ nanoparticles decorated with chitosan (chitosan-AgIO₃). The bionanocomposite was fully characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM) images, energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD). The antibacterial effect of chitosan-AgIO₃ bionanocomposite was investigated for Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus saprophyticus, Escherichia coli, and Staphylococcus aureus as pathogen microorganisms via the plate count method, disk diffusion method, and optical density (OD) measurements. The antibacterial performance of the bionanocomposite was compared with two commercial drugs (penicillin and silver sulfadiazine) and in some cases, the synthesized bionanocomposite has a better effect in the eradication of bacteria. The bionanocomposite represented great antibacterial properties. Flow cytometry was performed to investigate the mechanism of bionanocomposite as an antibacterial agent. Reactive oxygen species (ROS) production was responsible for the bactericidal mechanisms. These results demonstrate that the chitosan-AgIO₃ bionanocomposite, as a kind of antibacterial material, got potential for application in a broad range of biomedical applications and water purification. The design and synthesis of green and biodegradable antibacterial materials with simple processes and by using readily available materials cause the final product to be economically affordable and could be scaled in different industries.

Simultaneous improvements in antibacterial and flame retardant properties of PET by use of bio-nanotechnology for fabrication of high performance PET bionanocomposites

Recently, attentions to the applications of biotechnology and nanotechnology in the polymer industries have been greater than before. Hybrid nanocomposites containing multi-type of nano structures are widely established, but application of biotechnology for in-situ embedment of nanoparticles in polymer matrix is rarely reported. In this study, poly (ethylene terephthalate) (PET) based ternary bionanocomposites containing modified chitosan (phosphorylated chitosan) and nanosilver particles were prepared by simple eco-friendly method. Chitosan was selected as a biopolymer with respect to the biological activity and compatibility with PET. Phosphorylation of chitosan was achieved in order to introduce the phosphorus moieties as a flame retardant agent in PET matrix by using chemical approach. Also a cost-effective and environmentally friendly method was used for the in-situ fabrication and decoration of silver nanoparticles on to phosphorylated chitosan in PET matrix. Effects of the hybrid system (phosphorylated chitosan and silver nanoparticles) on the morphology, thermal behavior and antibacterial properties of the PET samples were investigated by different methods. The microstructure and homogeneity of the samples were analyzed by studying of dispersion of nanoparticles in PET via scanning electron microscopy. The antibacterial properties of PET nanocomposites can be improved by insertion of silver nanoparticles into the bulk of polymer matrix. Obtained results indicated that the PET/phosphorylated chitosan/silver nanocomposites showed a significantly higher growth inhibition rate compared with the PET and PET/phosphorylated chitosan blend. Also the flame retardant properties of PET nanocomposites were drastically enhanced.

Zwitterionic peptide-functionalized highly dispersed carbon nanotubes for efficient wastewater treatment

Multi-walled carbon nanotubes (MWCNTs) have displayed great potential as catalyst carriers due to their nanoscale structure and large specific surface area. However, their hydrophobicity and poor dispersibility in water restrict their applications in aqueous environments. Herein, the dispersibility of MWCNTs was significantly enhanced with a chimeric protein MPKE which consisted of a zwitterionic peptide unit and a mussel adhesive protein unit. The MPKE could be easily attached to MWCNTs (MPKE-MWCNTs) by a simple stirring process due to the versatile adhesion ability of mussel adhesive unit. As expected, the MPKE-MWCNTs displayed outstanding dispersibility in water (>7 months), as well as in alkaline solutions (pH = 12) and organic solvents (DMSO and ethanol) due to the hydrophilicity of the zwitterionic peptide unit. Moreover, the MPKE-MWCNTs were used as silver nanoparticle carriers for the reduction of 4-nitrophenol in wastewater, with the normalized rate constant k_nor up to 32.9 s^-1 mmol^-1. Meanwhile, they also exhibited excellent biocompatibility and antibacterial activity, which were favorable for wastewater treatment. This work provides a facile strategy for MWCNT modification, functionalization and applications in aqueous environments.

Sexual pheromone detection using PANI·Ag nanohybrid and PANI/PSS nanocomposite nanosensors

In this study, polyaniline/poly(styrene sulfonate) (PANI/PSS) nanocomposite and polyaniline·silver (PANI·Ag) nanohybrid thin films were obtained in cantilever nanosensors surface. The developed films were characterized in relation to topography, roughness, thickness, height, and structural properties. The topography study revealed that both films have a globular morphology, thickness and height in nanoscale. The gas sensing performance was investigated for sexual pheromone from the neotropical brown stink bug, Euschistus heros (F.). The sensitivities of both nanosensors based on PANI/PSS nanocomposite and PANI·Ag nanohybrid films were similar. The PANI·Ag nanohybrid nanosensor had a limit of detection of less than 3.1 ppq and limit of quantification of 10.05 ppq. The nanosensor layers were analyzed by UV-vis and FTIR showing the incorporation of Ag nanoparticles in the nanohybrid. We found that pheromone compound was adsorbed in sensing layer resulting in a reduction in the resonance frequency. The detection mechanism help us understand the good results of LOD, LOQ, sensitivity, selectivity and repeatability. The presented device has great potential for detection of the sexual pheromone from E. heros.

A Sulfhydryl Azobenzene-Modified Polyaniline/Silver Electrode and Its Photoswitching Electrochemical Performance

In this work, a sulfhydryl-functionalized azobenzene derivative (Azo) was synthesized and polyaniline/silver was modified (PANI/Ag) to make a nanocomposite (PANI/Ag/Azo). A series of characterization techniques like¹HNMR, UV-vis absorption spectra, Raman spectra, FT-IR, XRD, SEM, TEM, and TGA was employed to study Azo, PANI/Ag, and PANI/Ag/Azo. Electrochemical properties were measured by cyclic voltammetry (CV) and galvanostatic charging/discharging (GCD). CV showed that UV and blue light had hardly any effect on PANI/Ag. However, with the prolonged exposure time of UV light, the maximum CV current density of PANI/Ag/Azo rose from 1.24 to 2.72 A g^-1. Then, after 20 min of blue light irradiation, the maximum current density gradually recovered (from 2.72 to 1.26 A g^-1). The GCD also obtained similar results. After formula calculation, the specific capacitance of PANI/Ag/Azo also presented a reversible trend under the alternating irradiation of UV light and blue light. All the results show that PANI/Ag/Azo has a good photoelectric response, and its electrochemical performance can be reversibly adjusted by light. This result provides a new design idea for developing electrode materials with real-time electrochemical properties.

Investigating the Possibility of Green Synthesis of Silver Nanoparticles Using Vaccinium arctostaphlyos Extract and Evaluating Its Antibacterial Properties

Objective

Vaccinium genus plants have medicinal value, of which Vaccinium arctostaphylos (Caucasian whortleberry or Qare-Qat in the local language) is the only available species in Iran. Public tendency to use herbal remedies and natural products such as synthesized nanoparticles is increasing due to the proof of the destructive side effects of chemical drugs. Nanosilver products have been effective against more than 650 microbe types. This study was aimed at assessing the possibility of green synthesis of silver nanoparticles using Vaccinium arctostaphylos aqueous extract and at evaluating its antibacterial properties, as well.

Materials and Methods

In order to synthesize silver nanoparticles, different volumes of Vaccinium arctostaphylos aqueous extract (3, 5, 10, 15, and 30 ml) were assessed with different silver nitrate solution concentrations (0.5, 1, 3, 5, and 10 mM) and different reaction time durations (1, 3, 5, 10, and 20 minutes) at room temperature using a rotary shaker with a speed of 150 rpm. Ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction analysis (XRD), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) were carried out. The antibacterial activity of the aqueous extract and the synthesized nanoparticles was evaluated, as well.

Results

Silver nanoparticle formation process was confirmed with XRD analysis, transmission electron microscopy (TEM), and FTIR spectroscopy. The UV-Vis spectroscopy of silver colloidal nanoparticles showed a surface plasmon resonance peak at 443 nm under optimal conditions (3 ml aqueous extract volume, 1 mM silver nitrate solution concentration, and 3 min reaction time under sunlight exposure). The reduction of silver ions to silver nanoparticles in solution was confirmed, as well. Based on X-ray diffraction analysis, the size of silver nanoparticles was in the range of 7-16 nm. TEM images showed an even distribution of silver nanoparticles, with a spherical shape. FTIR spectroscopy demonstrated the presence of different functional groups of oxygenated compounds such as carboxyl, hydroxyl, and nitrogenous groups. The antibacterial properties of the synthesized nanoparticles were confirmed.

Conclusion

The synthesized nanoparticles showed more antibacterial properties against gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) than gram-negative ones (Escherichia coli and Salmonella enteritidis).

Antimicrobial and biological effects of polyaniline/polyvinylpyrrolidone nanocomposites loaded with silver nanospheres/triangles

Two Ag–PANI/PVP nanocomposites were prepared using in situ integration of AgNPs during oxidative aniline polymerization, accelerated by the presence of PVP, which as well minimized the risk of particle agglomeration and macroscopic precipitation.

Recent Developments in Polymer Nanocomposite-Based Electrochemical Sensors for Detecting Environmental Pollutants

The human population is generally subjected to diverse pollutants and contaminants in the environment like those in the air, soil, foodstuffs, and drinking water. Therefore, the development of novel purification techniques and efficient detection devices for pollutants is an important challenge. To date, experts in the field have designed distinctive analytical procedures for the detection of pollutants including gas chromatography/mass spectrometry and atomic absorption spectroscopy. While the mentioned procedures enjoy high sensitivity, they suffer from being laborious, expensive, require advanced skills for operation, and are inconvenient to deploy as a result of their massive size. Therefore, in response to the above-mentioned limitations, electrochemical sensors are being developed that enjoy robustness, selectivity, sensitivity, and real-time measurements. Considerable advancements in nanomaterials-based electrochemical sensor platforms have helped to generate new technologies to ensure environmental and human safety. Recently, investigators have expanded considerable effort to utilize polymer nanocomposites for building the electrochemical sensors in view of their promising features such as very good electrocatalytic activities, higher electrical conductivity, and effective surface area in comparison to the traditional polymers. Herein, the first section of this review briefly discusses the most important methods for polymer nanocomposites synthesis, such as in situ polymerization, direct mixing of polymer and nanofillers (melt-mixing and solution-mixing), sol-gel, and electrochemical methods. It then summarizes the current utilization of polymer nanocomposites for the preparation of electrochemical sensors as a novel approach for monitoring and detecting environmental pollutants which include heavy metal ions, pesticides, phenolic compounds, nitroaromatic compounds, nitrite, and hydrazine in different mediums. Finally, the current challenges and future directions for the polymer nanocomposites-based electrochemical sensing of environmental pollutants are outlined.

Dye Separation and Antibacterial Activities of Polyaniline Thin Film-Coated Poly(phenyl sulfone) Membranes

We fabricated a nanofiltration membrane consisting of a polyaniline (PANI) film on a polyphenylsulfone (PPSU) substrate membrane. The PANI film acted as a potent separation enhancer and antimicrobial coating. The membrane was analyzed via scanning electron microscopy and atomic force microscopy to examine its morphology, topography, contact angle, and zeta potential. We aimed to investigate the impact of the PANI film on the surface properties of the membrane. Membrane performance was then evaluated in terms of water permeation and rejection of methylene blue (MB), an organic dye. Coating the PPSU membrane with a PANI film imparted significant advantages, including finely tuned nanometer-scale membrane pores and tailored surface properties, including increased hydrophilicity and zeta potential. The PANI film also significantly enhanced separation of the MB dye. The PANI-coated membrane rejected over 90% of MB with little compromise in membrane permeability. The PANI film also enhanced the antimicrobial activity of the membrane. The bacteriostasis (B R) values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Escherichia coli were 63.5% and 95.2%, respectively. The B R values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Staphylococcus aureus were 70.6% and 88.0%, respectively.

Fabrication of multifunctional TANI/Cu2O/Ag nanocomposite for environmental abatement

During past decade, the ternary nanocomposite is ubiquitous in nanotechnology. Herein, a simple fabrication of cuprous oxide (Cu2O) and silver (Ag) nanoparticles into Tetraaniline (TANI) matrix by in situ-polymerization approach to attain Tetramer-Metal Oxide-Metal (TANI/Cu2O/Ag, shortly TCA) ternary composite was reported firstly. The synthesized materials were further characterized by a series of instrumental techniques to understand its structure, morphology and thermal properties. This nanocomposite showed promising applications in wastewater treatment by the testing of photocatalytic activity over the pararosaniline hydrochloride (PRA) dye degradation under visible light radiations, removal of Cadmium ion (Cd2+) by adsorption, corrosion resistance and antibacterial activity against both gram positive and gram negative bacterial strains. The obtained results of TCA compared with the pure TANI and binary nanocomposite (TANI/Cu2O) declared that the TCA composite is excellent material to solve the environmental issues due to lesser bandgap energy, visible light respond, high absorptivity, and long-life excitation.

Synthesis of Ag@PANI nanocomposites by complexation method and their application as label-free chemo-probe for detection of mercury ions

A novel optical probe consistinsg of Ag@PANI (silver-polyaniline) nanocomposites was developed for detection of mercury ions (Hg2+). The poly-dispersed Ag@PANI nanocomposites were synthesized by complexation reaction method. We studied structural and functional properties of polymer nanocomposites thoroughly. Ag@PANI nanocomposites consist of fibrous morphology with a mean particle size of 31.39 nm. Ag@PANI nanocomposites consist of face-centered cubic crystal structure with an average crystallite size of 19.41 nm. Raman spectroscopy was used in sensitive and selective detection of Hg2+ ions in dynamic range of 0.01–0.1 ppm with limit of detection of 0.019 ppm. Ag@PANI nanocomposite sensor for Hg (II) ions has shown some sublime results in pH range 3–5. Ag@PANI-based sensing probe can be beneficial for Hg2+ ions detection in highly sensitive biological, chemical and environmental analysis. Our sensing probe has shown good reproducibility, and all recorded observations revealed that sensing probe consisting of Ag@PANI nanocomposites is well suited for detection of Hg2+ ions.

Facile simultaneous synthesis of tetraaniline nanostructures/silver nanoparticles as heterogeneous catalyst for the efficient catalytic reduction of 4-nitrophenol to 4-aminophenol

Nanocomposites of tetraaniline (TAN) nanostructures/silver nanoparticles (Ag NPs) were synthesized by an interfacial polymerization method using N-phenyl-1, 4-phenylenediamine (NPPD), AgNO3 and ammonium persulphate (APS) as monomer, oxidizing agent in immiscible solvent toluene-water respectively. The structure and morphology of the as-prepared TAN and Ag NPs were investigated by UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and thermogravimetry (TG). The results of FTIR spectroscopy confirmed the formation of TAN and Ag NPs and those of XRD showed the presence of the face centred cubic (fcc) phase of Ag NPs. The FESEM and TEM images gave direct evidence that Ag NPs stabilized with the TAN nanostructures. TGA indicated the enhanced thermal stability of the nanocomposites (NCs). The catalytic activity of TAN/Ag NCs was investigated for the model reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of excess sodium borohydride.

Interfacially Interactive Ternary Silver-Supported Polyaniline/Multiwalled Carbon Nanotube Nanocomposites for Catalytic and Antibacterial Activity

Herein, a protocol strategy has been designed for the preparation of ternary silver nanoparticles-supported polyaniline multiwalled carbon nanotube (Ag NPs-PANI/MWCNT) nanocomposites with a chemical interaction for catalytic and antibacterial activity. The morphological study confirmed that Ag NPs were immobilized on the surface of PANI, and afterward, Ag NPs-PANI were mixed with the MWCNTs. The X-ray diffraction technique revealed the face-centered cubic structure of Ag NPs, and the X-ray photoelectron spectroscopy study revealed the chemical constituent and signature of π-π* and C-N interactions in the nanocomposites. The ternary Ag NPs-PANI/MWCNTs nanocomposites have the apparent rate of reaction (K _app) as 5.4 × 10^-3 s^-1, higher than binary nanocomposites for catalytic reduction of 4-nitrophenol to 4-aminophenol at room temperature. Antibacterial activity of Ag NPs-PANI/MWCNT nanocomposites is higher against pathogenic bacteria. Thereafter, because of multifold applications of ternary nanocomposites, they have a broad scope in the field of environmental and healthcare sectors.

Direct grafting of tetraaniline via perfluorophenylazide photochemistry to create antifouling, low bio-adhesion surfaces

Conjugated polyaniline has shown anticorrosive, hydrophilic, antibacterial, pH-responsive, and pseudocapacitive properties making it of interest in many fields. However, in situ grafting of polyaniline without harsh chemical treatments is challenging. In this study, we report a simple, fast, and non-destructive surface modification method for grafting tetraaniline (TANI), the smallest conjugated repeat unit of polyaniline, onto several materials via perfluorophenylazide photochemistry. The new materials are characterized by nuclear magnetic resonance (NMR) and electrospray ionization (ESI) mass spectroscopy. TANI is shown to be covalently bonded to important carbon materials including graphite, carbon nanotubes (CNTs), and reduced graphene oxide (rGO), as confirmed by transmission electron microscopy (TEM). Furthermore, large area modifications on polyethylene terephthalate (PET) films through dip-coating or spray-coating demonstrate the potential applicability in biomedical applications where high transparency, patternability, and low bio-adhesion are needed. Another important application is preventing biofouling in membranes for water purification. Here we report the first oligoaniline grafted water filtration membranes by modifying commercially available polyethersulfone (PES) ultrafiltration (UF) membranes. The modified membranes are hydrophilic as demonstrated by captive bubble experiments and exhibit extraordinarily low bovine serum albumin (BSA) and Escherichia coli adhesions. Superior membrane performance in terms of flux, BSA rejection and flux recovery after biofouling are demonstrated using a cross-flow system and dead-end cells, showing excellent fouling resistance produced by the in situ modification.

Preparation of polyaniline hollow microspheres/zinc composite and its application in lithium battery

Polyaniline (PANI) hollow microspheres were synthesized by a self-assembly method in aqueous solution of poly (2-acrylamido-2-methylpropane sulfonic acid) (PAMPS), and then microspheric zinc (Zn) was introduced into PANI to prepare PANI hollow microspheres/Zn composite. The structure and morphology of as-synthesized samples were investigated by Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and scanning electron microscopy, respectively. The charge/discharge property, cyclic voltammetry, and alternating current (AC) impedance spectroscopy of as-prepared samples were also examined in detail. The results showed that the electrical conductivity of PANI/Zn composite reached 21.2 ± 0.16 S/cm at 20 wt% of Zn, which was 11.4 S/cm higher than that of PANI. The first discharge capacity of PANI/Zn lithium battery reached 570.8 mAh/g at a current density of 0.2 mA/cm2. After 15 cycles, it remained at 159 mAh/g, which was 107 mAh/g higher than that of PANI lithium battery. Furthermore, the results of AC impedance test showed that the addition of Zn powders significantly reduced the internal resistance of battery. Compared with PANI, PANI/Zn composite showed greater capacity, higher conductivity, and charge/discharge efficiency, which was more suitable for the cathode material of high performance lithium battery.

Copper-polyaniline nanocomposite: Role of physicochemical properties on the antimicrobial activity and genotoxicity evaluation

Copper nanoparticles (Cu NPs) have proven to own excellent antimicrobial efficacy, but the problems of easy oxidation and aggregation limit their practical application. Here, nanocomposite based on polyaniline (PANI) and Cu NPs solved this problem and brought additional physicochemical properties that are markedly advantageous for antimicrobial applications. Current work exploits this potential, to examine its time- and concentration-dependent antimicrobial activity, employing E. coli, S. aureus, and C. albicans as a model microbial species. Regarding the presence of polaronic charge carriers in the fibrous polyaniline network, effects of Cu NPs' size and their partially oxidized surfaces (the data were confirmed by HRTEM, FESEM, XRD, Raman and XPS analysis), as well as rapid copper ions release, Cu-PANI nanocomposite showed efficient bactericidal and fungicidal activities at the concentrations ≤1 ppm, within the incubation time of 2 h. Beside the quantitative analysis, the high levels of cellular disruption for all tested microbes were evidenced by atomic force microscopy. Moreover, the minimum inhibitory and bactericidal concentrations of the Cu-PANI nanocomposite were lower than those reported for other nanocomposites. Using such low concentrations is recognized as a good way to avoid its toxicity toward the environment. For this purpose, Cu-PANI nanocomposite is tested for its genotoxicity and influence on the oxidative status of the human cells in vitro.

Role of Computed Tomography Volumetry in Estimating Liver Weights in Surgical Patients with Hepatic Steatosis

OBJECTIVES

Our objective was to assess the accuracy of computed tomography volumetry in estimating liver volume in steatotic patients.

MATERIALS AND METHODS

We divided 641 liver donors (mean age 27 years, 71% male) into 4 groups according to the extent of steatosis on predonation biopsy: with < 5% comprising group 1, 5% to 9% comprising group 2, 10% to 19% comprising group 3, and ≥ 20% comprising group 4. Graft mass estimation error (%) was calculated as follows: [(computed tomography-measured volume minus graft weight)/graft weight] × 100. We obtained estimation errors, intraclass correlation coefficients, and Pearson correlation coefficients across the groups.

RESULTS

Baseline alanine aminotransferase and gammaglutamyltranspeptidase values were signi ficantly correlated with extent of steatosis. Mean graft weight and computed tomography-measured volume were 725.9 g and 741.2 mL. Mean estimation errors were comparable (1.5% for group 1, 2.7% for group 2, 3.0% for group 3, and 3.9% for group 4; P = .77). In multivariate linear regression, estimation error was inversely correlated with high-density lipoprotein cholesterol (P = .008). Overall, there was an excellent agreement between measured volume and actual weight, with intraclass correlation coefficients over 0.85 and Pearson correlation coefficients over 0.70 in all groups (P < .001).

CONCLUSIONS

Preoperative computed tomography volumetry is an accurate tool for estimating volume regardless of the extent of steatosis.

High-Strength Konjac Glucomannan/Silver Nanowires Composite Films with Antibacterial Properties

Robust, high-strength and environmentally friendly antibacterial composite films were prepared by simply blending konjac glucomannan (KGM) and silver nanowires (Ag NWs) in an aqueous system. The samples were then characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetric analysis, mechanical property tests, Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS) and antimicrobial tests. The results showed that there was a high ratio of Ag NWs uniformly distributed in the composite films, which was vital for mechanical reinforcement and stable antibacterial properties. The enhanced thermal stability and mechanical intensity increased, while the elongation at break was reduced with an increase in the amount of Ag NWs found in the composite films. When the percentage of Ag NWs in the composite films reached 5%, the tensile strength was 148.21 MPa, Young's modulus was 13.79 GPa and the ultimate strain was 25.28%. Antibacterial tests showed that the KGM films had no antibacterial effect. After the addition of Ag NWs, the composite films had an obvious inhibitory effect on bacteria, with the uniform dispersion of Ag NWs promoting the antibacterial effect to a certain degree. These results indicated that these composite films would have a potential application in the fields of environmentally friendly packaging or medicine.

Antimicrobial Treatment of Polymeric Medical Devices by Silver Nanomaterials and Related Technology

Antimicrobial biocompatible polymers form a group of highly desirable materials in medicinal technology that exhibit interesting thermal and mechanical properties, and high chemical resistance. There are numerous types of polymers with antimicrobial activity or antimicrobial properties conferred through their proper modification. In this review, we focus on the second type of polymers, especially those whose antimicrobial activity is conferred by nanotechnology. Nanotechnology processing is a developing area that exploits the antibacterial effects of broad-scale compounds, both organic and inorganic, to form value-added medical devices. This work gives an overview of nanostructured antimicrobial agents, especially silver ones, used together with biocompatible polymers as effective antimicrobial composites in healthcare. The bactericidal properties of non-conventional antimicrobial agents are compared with those of conventional ones and the advantages and disadvantages are discussed.

A novel methodology for fabrication of Ag–polypyrrole core–shell nanosphere using microemulsion system and evaluation of its antibacterial application

A novel methodology based on microemulsion system was used to prepare Ag–PPy core–shell nanocomposite for antibacterial application

Influence of Dispersed Nanoparticles on the Kinetics of Formation and Molecular Mass of Polyaniline

Using a combination of the open circuit potential and pH profiles of aniline (An) polymerization and their mathematical treatment, we develop a new convenient semiquantitative approach to determine the influence of the dispersed nanoparticles (e.g., TiO₂ nanoparticles) on the kinetic features of this process and molecular mass of the formed polyaniline (PANI). It is revealed that the reciprocal values of the polymerization stages, namely, the duration of the induction period, of homogeneous and heterogeneous pernigraniline (PN) accumulation, and of PN reduction with An, are linear functions of the weight fraction of the nanoparticles. We found that when nanoparticles are added the weight-averaged molecular weight of PANI initially increases from 56 000 to 79 000 and the polydispersity index drops from 3.9 to 1.7. However, at high TiO₂ concentrations, the former dramatically decreases, whereas the latter increases. We use the relative proton concentration as a function of time and the different extents of acceleration of the consecutive stages of An polymerization to explain the changes in the molecular weight distribution of PANI with different contents of TiO₂ nanoparticles in the polymerization medium.

Electrochemical pore filling strategy for controlled growth of magnetic and metallic nanowire arrays with large area uniformity

While a variety of template-based strategies have been developed in the fabrication of nanowires (NWs), a uniform pore filling across the template still poses a major challenge. Here, we present a large area controlled pore filling strategy in the reproducible fabrication of various magnetic and metallic NW arrays, embedded inside anodic aluminum oxide templates. Using a diffusive pulsed electrodeposition (DPED) technique, this versatile strategy relies on the optimized filling of branched nanopores at the bottom of templates with Cu. Serving the Cu filled nanopores as appropriate nucleation sites, the DPED is followed by a uniform and homogeneous deposition of magnetic (Ni and Fe) and metallic (Cu and Zn) NWs at a current density of 50 mA cm^-2 for an optimal thickness of alumina barrier layer (∼18 nm). Our strategy provides large area uniformity (exceeding 400 μm²) in the fabrication of 16 μm long free-standing NW arrays. Using hysteresis loop measurements and scanning electron microscopy images, the electrodeposition efficiency (EE) and pore filling percentage (F _p) are evaluated, leading to maximum EE and F _p values of 91% and 95% for Ni and Zn, respectively. Moreover, the resulting NW arrays are found to be highly crystalline. Accordingly, the DPED technique is capable of cheaply and efficiently controlling NW growth over a large area, providing a tool for various nanoscale applications including biomedical devices, electronics, photonics, magnetic storage medium and nanomagnet computing.