Synthesis and characterization of novel comb-type amphiphilic graft copolymers containing polypropylene and polyethylene glycol

Amphiphilic comb-type graft copolymers containing polypropylene (PP) and polyethylene glycol (PEG) have been prepared. Polypropylene-g-polyethylene glycol comb-type thermoplastic amphiphilic copolymers were synthesized by the reaction between chlorinated polypropylene and polyethylene glycol in the presence of a base via a “grafting to” technique. A series of graft copolymers containing PEGs with molecular weights of 600 and 2,000 Da in the range of 4–34 mol% PEG were obtained. The amphiphilic graft copolymers with PEG segments in range between 20 and 30 mol% PEG displayed good film properties with elongation at break 275–440%. The hydrophilicity of the amphiphilic copolymers increases with the increasing PEG content in the copolymer while the mechanical properties decrease. Therefore, PP-g-PEG2000 with PEG contents in the range of 20–30 mol% PEG should be useful for medical and industrial applications where good film properties are needed.     

A Preliminary Assessment of Silver Nanoparticle Inhibition of Monkeypox Virus Plaque Formation

The use of nanotechnology and nanomaterials in medical research is growing. Silver-containing nanoparticles have previously demonstrated antimicrobial efficacy against bacteria and viral particles. This preliminary study utilized an in vitro approach to evaluate the ability of silver-based nanoparticles to inhibit infectivity of the biological select agent, monkeypox virus (MPV). Nanoparticles (10–80 nm, with or without polysaccharide coating), or silver nitrate (AgNO₃) at concentrations of 100, 50, 25, and 12.5 μg/mL were evaluated for efficacy using a plaque reduction assay. Both Ag-PS-25 (polysaccharide-coated, 25 nm) and Ag-NP-55 (non-coated, 55 nm) exhibited a significant (P ≤ 0.05) dose-dependent effect of test compound concentration on the mean number of plaque-forming units (PFU). All concentrations of silver nitrate (except 100 μg/mL) and Ag-PS-10 promoted significant (P ≤ 0.05) decreases in the number of observed PFU compared to untreated controls. Some nanoparticle treatments led to increased MPV PFU ranging from 1.04- to 1.8-fold above controls. No cytotoxicity (Vero cell monolayer sloughing) was caused by any test compound, except 100 μg/mL AgNO₃. These results demonstrate that silver-based nanoparticles of approximately 10 nm inhibit MPV infection in vitro, supporting their potential use as an anti-viral therapeutic.     

One-Pot Silver Nanoring Synthesis

Silver colloidal nanorings have been synthesized by reducing silver ions with NaBH₄ in trisodium citrate buffers. pH increase, by addition of NaOH, was used to speed up reduction reaction. The UV–vis absorption spectra of resulting silver nanorings showed two peaks accounting for transverse and longitudinal surface plasmon resonance, at ≈400 nm, and between 600 and 700 nm, respectively. The shapes of these silver nanoparticles (nanorings) depended on AgNO₃/NaBH₄ ratio, pH and reaction temperature. Particles were analysed by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. A reaction pathway is proposed to explain silver nanoring formation.     

Incorporation of Metallic Nanoparticles into Cosmetic Preparations and Assessment of Their Physicochemical and Utility Properties

A method was developed for introducing metallic nanoparticles (nanoAg and nanoAu) into cosmetic compositions (shampoos and soaps). Embedding of silver or gold nanoparticles into the composition imparts antimicrobial activity. Physicochemical properties of the prepared formulations were characterized. To confirm the presence of metallic nanoparticles, a UV–vis study was conducted. The size of embedded nanoparticles was determined using dynamic light scattering. The micrometric structure of the obtained products was characterized using scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM‐EDS) microscopy. A technique was developed for the assessment of nanoparticle release from cosmetic products as well as for the analysis of the penetration of nanoparticles through a model dermal membrane. The evaluation of accumulation of nanoparticles in model human body fluids was a crucial step in this study. The antimicrobial properties of final cosmetic formulations were studied using Aspergillus niger. The results confirmed that stable cosmetic formulations with embedded metallic nanoparticles were obtained. It was determined that nanoparticles are able to penetrate through a model dermal membrane. However, after 20 min of washing, the migration of nanoparticles was not confirmed. The obtained products exhibited biocidal activity against A. niger.     

A novel method for preparing silver/poly(siloxane‐b‐methyl methacrylate) nanocomposites with multiple properties in the DMF‐toluene mixture solvent

A novel method for preparing silver/poly(siloxane‐b‐methyl methacrylate) (Ag/(PDMS‐b‐PMMA)) hybrid nanocomposites was proposed by using the siloxane‐containing block copolymers as stabilizer. The reduction of silver nitrate (AgNO₃) was performed in the mixture solvent of dimethyl formamide (DMF) and toluene, which was used to dissolve double‐hydrophobic copolymer, as well as served as the powerful reductant. The presence of the PMMA block in the copolymer indeed exerted as capping ligands for nanoparticles. The resultant nanocomposites exhibited super hydrophobicity with water contact angle of 123.3^° and the thermogravimetry analysis (TGA) revealed that the resultant nanocomposites with more PDMS were more heat‐resisting. Besides, the antimicrobial efficiency of the most desirable nanocomposite (Ag/PDMS₆₅‐b‐PMMA₃₀ loaded with 7.3% silver nanoparticle) could reach up to 99.4% when contacting with escherichia coli within 120 min. As a whole, the resultant nanocomposites by the integration of excellent properties of silver nanoparticles as well as siloxane‐block copolymers can be a promising for the development of materials with hydrophobic, heat‐resisting and outstanding antibacterial properties from the chemical product engineering viewpoint. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4780–4793, 2013     

Diblock copolymers with an amorphous, high glass transition temperature, organometallic block: synthesis, characterisation and self-assembly of polystyrene-b-poly(ferrocenylisopropylmethylsilane) in the bulk state

Living anionic ring-opening polymerisation of isopropylmethylsila[1]ferrocenophane yields poly(ferrocenylisopropylmethylsilane) (PFiPMS) with controlled molecular weights and narrow polydispersities up to M_n = ca. 20,000 Da. Polystyrene-b-poly(ferrocenylisopropylmethylsilane) (PS-b-PFiPMS) diblock copolymers have been prepared via sequential living anionic polymerisation. These materials are examples of diblock copolymers with an amorphous, organometallic block with a glass transition temperature (T_g) above room temperature (60 °C). High molecular weight diblock copolymers (M_n = 42,000–51,000 Da) were targeted with low polydispersities (PDI = 1.1). As both blocks are amorphous, these materials self-assemble into predictable morphologies in the bulk state with well-ordered nanodomains.     

Spectroscopic analysis and catalytic application of biopolymer capped silver nanoparticle,an effective antimicrobial agent

Microbial reduction of silver ion (conc. 1 mM AgNO₃) was performed by Alkaliphilus oremlandii strain ohILAs in an alkaline pH 10. The synthesized silver nanoparticle was stabilized by poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) biopolymer which was also synthesized by the microbial culture of Alkaliphilus oremlandii strain ohILAs at pH8. The particle size and shape of the silver nanoparticles was studied by dynamic light scattering and under a transmission electron microscope and it was found that the particle size of polymer stabilized colloidal silver was comparatively lower (22–43nm) than that for the unstabilized one (63–93 nm). The stabilization of nanoparticles in polymer dispersed medium after around 60 days was confirmed from analysis of UV‐visible spectroscopy and scanning electron microscopy. The crystalline peaks as recorded with X‐ray's diffraction were observed at 2θ values of 38° and 43°, indicating the fcc crystalline structure of the silver nanoparticle. The antimicrobial activity of silver nanoparticles on gram‐negative bacteria strain (Escherichia coli XL1B) and gram‐positive strain (Lysinibacillus fusiformis) showed better performance by the solution of polymer stabilized nanoparticle than that for the non polymer stabilized one. The reduction of nitro group in p‐nitrophenol to p‐aminophenol was observed from the analysis of UV‐Visible spectroscopy in which, the shifting of absorption peak at 400 to 295 nm and the simultaneous regeneration of light brown color (λ_max 410 nm) of silver nanoparticles confirmed the catalytic activity of silver nanomaterials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41495.     

A comparative study of the effect of addition of CeO x and Li2O on γ-Al2O3 supported copper, silver and gold catalysts in the preferential oxidation of CO

In the study described in this paper we deposited gold, silver and copper on γ-Al₂O₃ as nanoparticles (<4 nm) and investigated the behavior of these nanoparticles in the preferential oxidation of CO in presence of H₂. In addition, the effect of addition of CeO _x and/or Li₂O was investigated. All the three metals show preferential oxidation of CO at low temperatures. The oxides added to Au/γ-Al₂O₃, Ag/γ-Al₂O₃ and Cu/γ-Al₂O₃ improve the catalytic performance of the gold, silver and copper. Interesting and synergistic effects were observed when both the CeO _x and Li₂O were added. Possible mechanisms are proposed.     

Biomimetic Synthesis of Gelatin Polypeptide-Assisted Noble-Metal Nanoparticles and Their Interaction Study

Herein, the generation of gold, silver, and silver–gold (Ag–Au) bimetallic nanoparticles was carried out in collagen (gelatin) solution. It first showed that the major ingredient in gelatin polypeptide, glutamic acid, acted as reducing agent to biomimetically synthesize noble metal nanoparticles at 80°C. The size of nanoparticles can be controlled not only by the mass ratio of gelatin to gold ion but also by pH of gelatin solution. Interaction between noble-metal nanoparticles and polypeptide has been investigated by TEM, UV–visible, fluorescence spectroscopy, and HNMR. This study testified that the degradation of gelatin protein could not alter the morphology of nanoparticles, but it made nanoparticles aggregated clusters array (opposing three-dimensional α-helix folding structure) into isolated nanoparticles stabilized by gelatin residues. This is a promising merit of gelatin to apply in the synthesis of nanoparticles. Therefore, gelatin protein is an excellent template for biomimetic synthesis of noble metal/bimetallic nanoparticle growth to form nanometer-sized device.     

Synthesis of Nanocomposites of Metal Nanoparticles Utilizing Miscible Polymers

Summary Gold nanoparticles modified with poly(2–methyl–2–oxazoline) have been prepared via chemical reduction of HAuCl₄ by NaBH₄. The gold nanoparticles were homogeneously dispersed in poly(vinyl chloride) as a polymer matrix by the miscibility between the protecting polymer of the nanoparticle and the polymer matrix. Differential scanning calorimetry and UV–vis absorption measurement clearly showed that the miscibility played an important role for incorporation of the metal nanoparticles in the polymer matrix.     

Preparation,morphology and sonication time dependence of silver nanoparticles in amphiphilic block copolymers of PEO with polystyrene or PMMA

Composite materials comprising arrays of silver nanoparticles in amphiphilic copolymers have been prepared by sonochemically enhanced borohydride reduction of precursor silver nitrate (AgNO₃). The precursor was incorporated into the cores of polymeric micelles formed from block copolymers of polystyrene (PS) or poly(methyl methacrylate) (PMMA) with poly(ethylene oxide) (PEO). The copolymers were synthesised with varying hydrophobic block lengths from a PEO macroinitiator by atom transfer radical polymerization (ATRP). UV/visible spectroscopy was used to confirm the formation of elemental silver and the effect of sonication time on the appearance of the silver nanoparticles was determined. The growth was faster than when gold nanoparticles are formed in comparable block copolymers. Nanoparticles formed in copolymers with PMMA blocks were more stable to agglomeration than when polystyrene was used. Electron microscopy revealed the morphology of the nanocomposites which confirmed that both block copolymers are vehicles for the formation of well-defined films containing nanoparticulate silver. However, AgNP formation shows some significant differences from previous reports of gold NP containing materials formed under similar conditions.     

Effect of Hydrophobicity of PEO–PPO–PEO Block Copolymers on Micellization and Solubilization of a Model Drug Nimesulide

The present work explored the molecular implications governing the solubilization of a model drug nimesulide (NIM) in micelles of ethylene oxide-propylene oxide (EO–PO) triblock copolymers. The aggregation behavior and solubilization studies on four copolymers each with the same mol mass of central PPO block equal to 2,250 and varying % PEO was examined by means of UV–VIS. Moreover, high-sensitivity differential scanning calorimetry, and Fourier transform infrared spectrometry measurements were used to evaluate the critical micellization temperature. The solubilization at different temperatures (30, 37, 45 °C), pH (2 to 10) and in the presence of added sodium chloride (0–2 M) was monitored and the partition coefficient (P) and the free energy of solubilization (ΔG _s^o) were calculated. The site of solubilization of NIM in micelles was also probed. The NIM solubility decreased with increases in the PEO molecular weight; the drug resides in the micelle core.     

Amperometric hydrogen peroxide biosensor based on a modified gold electrode with silver nanowires

A novel amperometric biosensor for the detection of hydrogen peroxide (H₂O₂) was prepared by immobilizing horseradish peroxidase (HRP) on highly dense silver nanowire (Ag-NW) film. The modified electrode was characterized using UV–Vis spectroscopy, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The electrochemical performances of the electrode were studied by cyclic voltammetry and chronoamperometry. The HRPs immobilized on the surface of Ag-NWs exhibited an excellent electrocatalytic response toward reduction of H₂O₂. The resulting Ag-NW modified sensor showed a sensitivity of ~2.55 μA μM⁻¹ (correlation coefficient r = 0.9969) with a linear range of 4.8 nM–0.31 μM. Its detection limit was 1.2 nM with a signal-to-noise ratio of 3. The Michaelis–Menten constant K_M^app and the maximum current density I _max of the modified electrode were 0.0071 mM and 8.475 μA, respectively. The preparation process of the proposed biosensor was convenient, and the resulting biosensor showed high sensitivity, low detection limit and good stability.     

Optical application of poly(HEMA-<Emphasis Type="Italic">co</Emphasis>-MMA) containing silver nanoparticles and N,N-dimethylacrylamide

High functional ophthalmic lens materials, poly(HEMA-co-MMA)s, were prepared by the copolymerization of HEMA, MMA, NVP, EDGMA, and N,N-dimethylacrylamide in the presence of silver nanoparticles. Silver nanoparticles have antimicrobial properties and a hydrophilic monomer N,N-dimethylacrylamide has excellent biocompatibility and oxygen transmissibility. The water content was in the range of 36.63–44.45%, indicating the characteristics of general water-content contact lenses, and the refractive index was measured to be in the range of 1.423–1.435. Meanwhile, the oxygen transmissibility ranged from 10.63×10⁻¹¹ to 18.85×10⁻¹¹ (cm²/sec)(mlO₂/ml×mmHg) increasing with increasing the addition ratio of N,N-dimethylacrylamide. The polymeric materials satisfied the basic characteristics required for ophthalmic contact lenses. The polymers can be used to fabricate antimicrobial hydrogel contact lenses with high oxygen transmissibility.     

Preparation of silver nanoparticle functionalized polyamide fibers with antimicrobial activity and electrical conductivity

In this work, silver nanoparticle functionalized polyamide 6 (PA6) fibers were prepared using the electroless plating method. The surface of PA6 fibers was modified by exploiting dopamine/CuSO₄/H₂O₂ system prior to electroless plating to enhance the bonding force between the fiber and the silver nanoparticles. It was found that both the formation rate and the chemical stability of polydopamine (PDA) coatings on the PA6 fiber surface were improved by the introduction of CuSO₄/H₂O₂. The results confirmed the successful deposition of silver nanoparticles on PA6 fiber surface and the average particle diameter of 223 nm. Compared with uncoated fibers, the silver plated PA6 fibers exhibited excellent antimicrobial activity to both Escherichia coli and Staphylococcus aureus (with an antimicrobial efficiency of 99.9% and 100%, respectively). The electrical resistance of the silver coated PA6 fibers reached 0.98 Ω over a length of 1 cm, indicating a good electrical conductivity. In particular, coating durability of the formed silver layer was investigated by subjecting the fibers to various mechanical deformations, and the results showed that the formed silver layer was maintained well after 50 times of cyclic stretching at a constant displacement of 10 mm. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47584.     

Magnetic Properties of FePt Nanoparticles Prepared by a Micellar Method

FePt nanoparticles with average size of 9 nm were synthesized using a diblock polymer micellar method combined with plasma treatment. To prevent from oxidation under ambient conditions, immediately after plasma treatment, the FePt nanoparticle arrays were in situ transferred into the film-growth chamber where they were covered by an SiO₂ overlayer. A nearly complete transformation of L1₀ FePt was achieved for samples annealed at temperatures above 700 °C. The well control on the FePt stoichiometry and avoidance from surface oxidation largely enhanced the coercivity, and a value as high as 10 kOe was obtained in this study. An evaluation of magnetic interactions was made using the so-called isothermal remanence (IRM) and dc-demagnetization (DCD) remanence curves and Kelly–Henkel plots (ΔM measurement). The ΔM measurement reveals that the resultant FePt nanoparticles exhibit a rather weak interparticle dipolar coupling, and the absence of interparticle exchange interaction suggests no significant particle agglomeration occurred during the post-annealing. Additionally, a slight parallel magnetic anisotropy was also observed. The results indicate the micellar method has a high potential in preparing FePt nanoparticle arrays used for ultrahigh density recording media.     

Homopolymer of 4-chloro-3-methyl Phenyl Methacrylate and its Copolymers with Butyl Methacrylate: Synthesis, Characterization, Reactivity Ratios and Antimicrobial Activity

The methacrylate monomer 4-chloro-3‐methyl phenyl methacrylate (CMPM) was synthesized by reacting 4-chloro-3‐methyl phenol with methacryloyl chloride. The homopolymer and various copolymers of CMPM with n-butyl methacrylate were synthesized by free-radical polymerization in toluene at 70°C using 2,2′-azobis(isobutyronitrile) as the initiator. The CMPM monomer was characterized by Fourier transform IR and ¹H-NMR studies. The copolymers were characterized by IR spectroscopy. The molecular weights (M _n and M _w) and the polydispersity index were obtained from gel permeation chromatography. The solubility and intrinsic viscosity of the homopolymer and the copolymers are also discussed here. The copolymer composition obtained from UV spectra led to the determination of reactivity ratios employing Fineman-Ross and Kelen-Tudos linearization methods. Thermogravimetric analyses of the homopolymer and the copolymers were carried out under a nitrogen atmosphere. The homopolymer and the copolymers prepared were tested for their antimicrobial activity against bacteria, fungi and yeasts.     

Silver/Polyaniline Nanocomposite for the Electrocatalytic Hydrazine Oxidation

Silver/polyaniline (Ag-PANi) nanocomposites were prepared via in situ reduction of silver in aniline by mild photolysis performed with short wavelength (365 nm) radiation from UV lamp for 12 h. Reduction of the silver in aqueous aniline leads to the formation of silver nanoparticles which in turn catalyze oxidation of aniline into polyaniline. A slightly broadened X-ray diffraction (XRD) pattern suggests small particle which was size consistent with cubic silver nanoparticles. The UV–Vis absorption revealed that the bands at about 400–420 nm due to benzonoid ring of the polyaniline are overlapped and blue-shifted due to the presence of silver nanoparticles in powdered state. Scanning electron microscopy (SEM) of the silver/polyaniline (Ag-PANi) nanocomposite showed a size distribution with nanofibers and granular morphology of silver nanoparticles. Our findings are not only the promising approach for electro-catalytic hydrazine oxidation but also utilized in the other bio-sensing applications.     

Fabrication of silver nanoparticles via self-regulated reduction by 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate

Silver nanoparticles exhibiting antimicrobial properties via self-regulated reduction were successfully prepared by using hydroxylated ionic liquids in an aqueous phase without additives. A new water-phase synthesis of silver nanoparticles using 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([HEMIm][BF₄]) and 1-(2′-hydroxyethyl)-2-methyl-3-dodecylimidazolium chloride ([C₁₂HEMIm][Cl]) was described. 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate serves as both a reductant and a stabilizer in this fabrication. Furthermore, we presented the antimicrobial properties of the resulting silver nanoparticles through the minimal inhibitory concentrations (MIC) test.     

Microorganism adhesion inhibited by silver doped Yttria-stabilized zirconia ceramics

The aim of this study was to incorporate silver nanoparticles into yttria-stabilized zirconia (YSZ) ceramic for eliminating microorganism adhesion on dental restoration graft. Y₂O₃ (3% mol) partially stabilized ZrO₂ powder with particle size around 80 nm was employed to fabricate tetragonal phase dominated YSZ ceramic block. Silver nanoparticles were efficiently loaded at pH 9.5 by NaBH₄ reducing of AgNO₃. The biocompatibility of silver incorporated YSZ was evaluated by MTT assay. Antimicrobial activities were quantitatively determined by optical density measurement and qualitatively analysed by scanning electro microscope. Inductively coupled plasma-mass spectrometry (ICP-MS) revealed that YSZ block containing 0.0047 wt% nanosilver, which is safe to mammalian cell, can inhibit the growth of Escherichia coli, Streptococcus mitis and Candida albicans. The pristine YSZ disc had no effect on bacterial growth. This study suggests that silver nanoparticles incorporated into YSZ blocks possess a broad spectrum antimicrobial effect and may help prevent biofilm formation on their surfaces to improve implant survival rate.