Antibiotic protected silver nanoparticles for microbicidal cotton

Surface coating of metal nanoparticles is one of the major aspects to be optimized in the design of antimicrobial nanoparticles. The novelty of this work is that antimicrobial derivatives have been used as stabilizers to protect silver nanoparticles (Ag NPs). Microbicidal activity studies of fabricated cotton textiles coated with these Ag@Antibio were performed. Protective ligand layers of Ag NPs resulted to be a deterministic factor in their antimicrobial activity. The best bactericidal activity was obtained for Fabric TAM (coated with Ag NPs with triarylmethane derivates in surface, Ag@TAMSH), with a bacterial decrease of 3 log units for the S. aureus strain. Intrinsic antibiotic activity and partial positive charge of the TAMSH probably enhanced their antimicrobial effects. Fabric Eu (coated with Ag NPs with eugenol derivates in surface, Ag@EugenolSH) and Fabric FQPEG (coated with Ag NPs embedded in PEG-fluoroquinolone derivatives in surface, Ag@FQPEG) displayed antibacterial activity for both Staphylococcus aureus and Pseudomonas aeruginosa strains. These coated antimicrobial cotton fabrics can be applied in different medical textiles.     

Biogenic synthesis from <Emphasis Type="Italic">Prunus</Emphasis> × <Emphasis Type="Italic">yedoensis</Emphasis> leaf extract,characterization, and photocatalytic and antibacterial activity of TiO<Subscript>2</Subscript> nanoparticles

Green synthesis of TiO₂ nanoparticles (NPs) from Prunus × yedoensis leaf extract (PYLE), and their application for removal of phosphate and their antibacterial activity, were studied for the first time. NPs were obtained using a green chemistry approach from 0.1 M TiO₂ and PYLE at ratio of 1:1 (v/w). Initial confirmation of production of TiO₂ NPs was provided by a color change from white to light yellow, then calcination was performed at 500 °C for 1 h. The TiO₂ NPs were characterized using various analytical techniques such as ultraviolet–visible (UV–Vis) spectroscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The results indicated that the optimal amount of TiO₂ NPs for removal of phosphate was 10 mg/l (10 ppm) with duration of 25 min. Furthermore, the antibacterial activity of TiO₂ NPs was also investigated using two different bacteria (Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli) in aqueous medium. The results revealed highly efficient sunlight-driven photocatalytic and antibacterial activity of TiO₂ NPs.     

Facile synthesis of Pd-decorated ZnO nanoparticles for acetone sensors with enhanced performance

ZnO and Pd nanoparticles (NPs) with average diameter of 38 and 10 nm were prepared in advance through a chemical solution method. Pd-functionalized ZnO nanoparticles (Pd@ZnO) were simply synthesized by adding ethanol solution of Pd NPs into ZnO powder, and annealing in argon atmosphere at 500 °C for 1 h after grinding for 30 min. The morphology and structure of the materials were systemically analyzed using Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. A weak peak in the XRD pattern of Pd@ZnO belonging to the (111) plane of elemental Pd indicated successfully loading of Pd. EDS and TEM results further confirmed successfully coating of Pd NPs onto the surface of ZnO. Sensors using ZnO NPs decorated with Pd (1 wt%) on the surface of exhibited highly elevated sensitivity of 76 in comparing with the response of 36 when based on pure ZnO NPs. In addition, such modification also resulted in a decrease in the operating temperature from 370 to 340 °C for 100 ppm acetone vapor. The sensing mechanism of the sensor based on Pd@ZnO NPs is discussed. Addition of Pd NPs can play an important role in improving the performance of gas sensors, including high sensitivity, good selectivity, and short response/recovery times.     

Internally dispersed synthesis of uniform silver nanoparticles via in situ reduction of [Ag(NH3)2]+ along natural microfibrillar substructures of cotton fiber

Silver nanoparticles (Ag NPs) are known to have efficient antimicrobial properties, but the direct application of Ag NPs onto the surface of textiles has shown to be ineffective and raise environmental concerns because Ag NPs leach out during washing. In this study, non-leaching and stable Ag-cotton nanocomposite fiber was produced by the in situ formation of Ag NPs inside the cotton fiber. The reported method is to introduce a nanofluidic system in alkali-swollen cotton fiber. Sequential flows of [Ag(NH₃)₂]⁺ and reductant aqueous fluids into the opened microfibrillar channels yielded a self-assembly of Ag ions on the deprotonated cellulose and subsequent nucleation and particle growth on the microfibrils. Transmission electron and field emission scanning electron microscopy images showed Ag NPs evenly dispersed throughout the entire cross-section of the fiber and their fixation onto the isolated secondary cell wall, respectively. Despite the rapid reduction reaction and the absence of a stabilizing agent, the successful formation of monodispersed Ag NPs (12 ± 3 nm) was attributed to the self-controlled function of the highly organized microfibrillar substructures, which regulated the transport and mixing of reactants. Incorporation of Ag NPs into the internal structure of the cotton fiber did not significantly influence the cotton crystalline structure.     

Low degree of substitution cellulosic textile coatings with improved physiological parameters

To further improve the physiological properties of textiles, solutions of low degree of substitution cellulose derivatives, i.e. carbamates and acetates, containing finely dispersed sub-micron scaled NaCl particles (d₁₆ = 269 nm, d₅₀ = 275 nm, d₈₄ = 283 nm) serving as templates were coated on textiles. By wet milling of NaCl particles in a 12.5 wt% solution of polyvinylpyrrolidone in dimethylacetamide (DMAc) as dispersing agent, a stable, processable dispersion was obtained, which could be diluted with LiCl/DMAc without any flocculation. For the preparation of the coating solution, the NaCl/DMAc dispersions were diluted with LiCl/DMAc and added to the DMAc-swollen cellulose derivatives. After application onto the textiles, the NaCl particle-containing coating had to be coagulated directly after application in a solvent bath, otherwise slow replacement of hygroscopic DMAc by water lead to the dissolution and recrystallisation of NaCl on the surface of the coating, thereby changing particle distribution and diameter. The solvent for the coagulation bath was chosen in a way that it allows for a high coagulation speed for the cellulose derivative matrix while possessing a low solubility product for NaCl (e.g., 2-propanol) in order to prevent any loss of the NaCl particles. Due to the highly porous structure created, increased water retention values and increased water vapour permeabilities were observed under preservation of the number of accessible hydroxyl groups of the cellulose derivatives. Both the templated and non-templated coatings could be processed on various textile substrates (e.g., on PET and PP). An important feature of these new materials, i.e. the possibility to apply an antibacterial finish, is discussed within the context of a potential use in the medical sector.     

Combined static electromagnetic radiation and plant extract contribute to the biosynthesis of instable nanosilver responsible for the growth of microstructures

The instant biosynthesis of silver nanoparticles under static electromagnetic induction, its antibacterial activity and its post exposure monitoring were reported here. A mix of silver nitrate solution and Ruta chalepensis leaf extract was irradiated by a static electromagnetic field (SMF) of 200 mT. The characteristics and stability of the biosynthesized silver nanoparticles (Ag NPs) were determined. Compared to the non-irradiated exposure, the morphology and state of the obtained material change once the exposition to SMF is turned off. Shifting from 453 to 473 nm, the percentage of the needles shaped silver nanoparticles increased and continue to win and dominate the biomixture toward the spherical silver nanoparticles. TEM microscopy showed a wide range of silver materials designed in different nanoscale morphology and beyond where they undergo major changes affecting mainly the size, shape and form (dispersity) of nanosilver.     

The Antimicrobial Effects and Metabolomic Footprinting of Carboxyl-Capped Bismuth Nanoparticles Against Helicobacter pylori

Organic salts of bismuth are currently used as antimicrobial agents against Helicobacter pylori. This study evaluated the antibacterial effect of elemental bismuth nanoparticles (Bi NPs) using a serial agar dilution method for the first time against different clinical isolates and a standard strain of H. pylori. The Bi NPs were biologically prepared and purified by a recently described method and subjected to further characterization by infrared spectroscopy and anti-H. pylori evaluation. Infrared spectroscopy results showed the presence of carboxyl functional groups on the surface of biogenic Bi NPs. These biogenic nanoparticles showed good antibacterial activity against all tested H. pylori strains. The resulting MICs varied between 60 and 100 μg/ml for clinical isolates of H. pylori and H. pylori (ATCC 26695). The antibacterial effect of bismuth ions was also tested against all test strains. The antimicrobial effect of Bi ions was lower than antimicrobial effect of bismuth in the form of elemental NPs. The effect of Bi NPs on metabolomic footprinting of H. pylori was further evaluated by ¹H NMR spectroscopy. Exposure of H. pylori to an inhibitory concentration of Bi NPs (100 μg/ml) led to release of some metabolites such as acetate, formic acid, glutamate, valine, glycine, and uracil from bacteria into their supernatant. These findings confirm that these nanoparticles interfere with Krebs cycle, nucleotide, and amino acid metabolism and shows anti-H. pylori activity.     

Green synthesis of silver nanoparticles using different volumes of <Emphasis Type="Italic">Trichodesma indicum</Emphasis> leaf extract and their antibacterial and photocatalytic activities

Silver nanoparticles (Ag NPs) were prepared by a green synthesis process, using Trichodesma indicum (T. indicum) leaf extract at different (5, 10 and 15 mL) concentrations. The formation of Ag NPs was confirmed by UV–Vis spectrophotometry with surface plasmon resonance at 443 nm. After this confirmation, the influence of leaf extract concentrations on the structural and surface morphological properties was studied. Along with their physical properties, antibacterial activity against pathogenic (B. cereus and E. coli) bacteria and photocatalytic de-colorization of methylene blue (MB) were examined. The XRD studies revealed that all the nanoparticles exhibited preferential orientation along the (111) plane of silver. The crystallite size decreases as the extract concentration is increased. From SEM images, it was found that the particles are spherical in shape and the size of the particles decreased drastically when the leaf extracts concentration is greater than 10 mL. The images strongly support the result observed from the SEM studies. FT-IR analysis showed that the plant compounds are involved in the reduction of Ag⁺ ions to Ag⁰. Ag NPs synthesized in 15 mL of leaf extract greatly resist the growth of both species and decomposed 82% of MB within 210 min. This ability of Ag NPs can be due to the small spherical-shaped particles and larger Ag⁺ ion release.     

Pericellular matrix plays an active role in retention and cellular uptake of large-sized nanoparticles

As the outmost coating of cells, the pericellular matrix (PCM) involved in various cellular functions has been exploited previously to be able to accumulate 120 nm Au nanoparticles (NPs), adjust their diffusion coefficient similar to that of membrane receptors, and enhance their uptake efficiency. In this study, the interactions between PCM and NPs with different sizes and materials were systematically investigated. We found that PCM can selectively enhance the retention and cellular uptake of NPs with diameters from 50 to 180 nm, but has no enhancement effect for 20 nm NPs. Identical behaviors of PCM was observed for both Au NPs and polystyrene NPs, indicating that this unique phenomenon is more related to the dimensions of the NPs. The study of single-particle tracking of 50–180 nm NPs on the surface of thick PCM cells revealed that PCM actively adjusts the diffusion coefficient of NPs to ～0.1 μm²/s regardless of their sizes. By blocking the receptor-mediated endocytosis (RME) pathway with four different inhibitors, this active role of PCM can be effectively suppressed, further confirming that the trapping and retention of NPs by PCM is an inherent biological function. These findings provided new insights for better understanding of the RME pathway and may have promising NP-based applications for controlled drug delivery and therapy in biomedicine.

Green Synthesis of Silver Nanoparticles Using <Emphasis Type="Italic">Commiphora caudata</Emphasis> Leaves Extract and the Study of Bactericidal Efficiency

The present study reports the synthesis of silver nanoparticles (Ag NPs) from silver nitrate solution using leaf extracts of Commiphora caudata. The formation of Ag NPs in the colloidal solution is confirmed by UV–Vis spectroscopy analysis. The identification of biomolecules is analyzed through fourier transform infrared spectroscopy. X-ray diffraction pattern shows that an average particle size of the synthesized nanoparticles are in the range of 40–24 nm. Field emission scanning electron microscopy and transmission electron microscopy confirm the formation Ag NPs in spherical shape. The photoluminescence study of the synthesized Ag NPs interprets the influence of C caudata leaf concentrations on emission behavior. Zeta potential measurement is carried out to determine the stability of synthesized Ag NPs. GC–MS analysis revealed that the C. caudata contained 11 compounds, such as Stigmasterol (24.14 %), Hexacosanoic acid, methyl ester (15.13 %) and 2-bromophenyl morpholine-4-carboxylate (11.71 %). The antibacterial activity of Ag NPs shows that these bio capped Ag NPs have higher inhibitory action for Escherichia coli, Klebsiella pheumoniea, Micrococcus flavus, Pseudomonas aeruginosa, Bacillus subtilis, Bacillus pumilus, Staphylococcus aureus.     

Antibacterial effect of silver nanoparticles deposited on corona‐treated polyester and polyamide fabrics

The possibility of using a corona treatment (electrical discharge at atmospheric pressure) for fiber surface activation, which can facilitate the loading of silver nanoparticles (NPs) from colloids onto the polyester (PES) and polyamide (PA) fabrics and thus improve their antibacterial properties, was studied. Bactericidal efficiency and its laundering durability on silver‐loaded fabrics for Gram‐positive bacterium Staphylococcus aureus and Gram‐negative bacterium Escherichia coli were evaluated. The fiber morphology after corona treatment and subsequent loading of silver NPs was followed by SEM. Corona‐treated fabrics loaded with silver NPs exhibited better antibacterial properties in comparison with untreated fabrics. In order to obtain acceptable laundering durability, it is necessary to use highly concentrated silver colloids. Copyright © 2008 John Wiley & Sons, Ltd.     

Green Synthesis of Silver Nanoparticles Using Arachis hypogaea (Ground Nut) Root Extract for Antibacterial and Clinical Applications

The present study focused on the green synthesis of silver nanoparticles (AgNPs) using Arachis hypogaea (ground nut) root extract for the antibacterial and clinical application. The presence of major phytochemical compounds are found to be 2H-Pyaran,2,5-diethenyltetrahydro, Didodecyl phthalate, Decanoic acid, Tetradecanoic acid, Bis(2-ethylhexyl) phthalate, Dodecanoic acid, Phosphonic acid, 2-(4-Methoxyphenyl)-5-(4-methoxynaphthyl) thiophene and Methyl 2-(N-Benzylimino)-4-chloro-3,3-dimethylbutanoate by GC–MS. Nanoparticles synthesis is confirmed by UV–Vis analysis by observing the maximum absorption spectrum at 450 nm. XRD and SEM–EDX results reveals the synthesized nanoparticles are cubic crystalline with agglomerated particles of silver oxide with biomolecules present around it. TEM images clearly shows that the biosynthesized nanoparticles are mostly spherical and irregular shaped with an average particles size of 30 nm. Highest susceptibility pattern of silver nanoparticle against Enterococcus sp. (35 ± 0.4 mm) which followed by Pseudomonas sp. (33 mm) and Staphylococcus aureus (29 mm). Green synthesized nanoparticles are coated over the commercially available clinical band aid cloth by dip coating method. Silver nanoparticle incorporated band aid cloth showed good antibacterial activity against the harmful bacteria which usually cause infection and interfere during wound healing. Our findings revealed that green nanoparticle has a good antibacterial action against harmful bacteria and showed good response for efficient clinical application.     

Efficient Immobilization of Porcine Pancreatic α-Amylase on Amino-Functionalized Magnetite Nanoparticles: Characterization and Stability Evaluation of the Immobilized Enzyme

The potential of the modified magnetic nanoparticles for covalent immobilization of porcine pancreatic α-amylase has been investigated. The synthesis and immobilization processes were simple and fast. The co-precipitation method was used for synthesis of magnetic iron oxide (Fe₃O₄) nanoparticles (NPs) which were subsequently coated with silica through sol–gel reaction. The amino-functionalized NPs were prepared by treating silica-coated NPs with 3-aminopropyltriethoxysilane followed by covalent immobilization of α-amylase by glutaraldehyde. The optimum enzyme concentration and incubation time for immobilization reaction were 150 mg and 4 h, respectively. Upon this immobilization, the α-amylase retained more than 50 % of its initial specific activity. The optimum pH for maximal catalytic activity of the immobilized enzyme was 6.5 at 45 °C. The kinetic studies on the immobilized enzyme and its free counterpart revealed an acceptable change of K_m and V_max. The Km values were found as 4 and 2.5 mM for free and immobilized enzymes, respectively. The V_max values for the free and immobilized enzymes were calculated as 1.75 and 1.03 μmol mg^?1 min^?1, in order, when starch was used as the substrate. A quick separation of immobilized amylase from reaction mixture was achieved when a magnetically active support was applied. In comparison to the free enzyme, the immobilized enzyme was thermally stable and was reusable for 9 cycles while retaining 68 % of its initial activity.     

Preparation of Surface-Imprinted Polymer Magnetic Nanoparticles with Miniemulsion Polymerization for Recognition of Salicylic Acid

Molecular surface-imprinted polymers nanoparticles encapsulating magnetite modified with oleic acid, for recognition of salicylic acid was prepared by three-step miniemulsion polymerization. The important factors including polymerization process, solvents, miniemulsifying approaches, and co-stabilizer have been investigated to obtain magnetic molecular imprinting polymers (MMIPs) nanoparticles (NPs) with high saturation magnetization (Ms), regular morphology, and good monodispersion. The results showed that the amount of magnetite encapsulated in MMIPs NPs was 43.4 wt% and Ms was 33.584 emu/g. Thus, MMIPs NPs could be separated easily within 2 minutes by an external magnetic field. The transmission electron microscope (TEM) showed MMIPs NPs were of regular sphere with core-shell structure, where magnetite NPs were uniformly encapsulated in homogeneous polymer shells. The average diameter of MMIPs NPs was 98 nm with RSD of 6.6%. Good recognition and high loading of target molecule were achieved by MMIPs NPs in batch rebinding tests.     

Recent Advances on Antimicrobial and Anti-Inflammatory Cotton Fabrics Containing Nanostructures

Hydrophilic cotton textiles, used in hospitals and sportswear, are prone to the growth of microorganisms (bacteria, fungi) resulting in hygiene and health risks. Thus, healthcare concerns have motivated the interest for the development of multifunctional antimicrobial cotton fabrics. Moreover, cotton textiles are also used in medical applications such as wound dressings. Their functionalization with anti-inflammatory agents is desirable in order to accelerate cicatrisation in the treatment of chronic wounds. This review summarizes recent advances (from January 2016 to January 2021) on the modification and coating of cotton fabrics with nanostructures (mainly metal and metal oxide nanoparticles, functionalized silica nanoparticles) to provide them antimicrobial (antibacterial and antifungal) and anti-inflammatory properties.     

Ag nanoparticles for determination of bisphenol A by resonance light-scattering technique

Resonance light-scattering (RLS) technique was developed for studying the interaction of silver nanoparticles (Ag NPs) with bisphenol A. A simple and environmentally friendly method was developed to synthesize Ag NPs using cinnamon extract. Synthesized nanoparticles were characterized using various measurement techniques. The synthesized Ag NPs were nearly spherical, with the sizes ranging from 30 to 60 nm. Spectral analysis indicated that the cinnamon extract acted as the reducing and capping agents on the surface of Ag NPs. RLS technique was used as the detection method. Light-scattering properties of the synthesized nanoparticles in the presence or absence of bisphenol A was selected as the detection signal. Under the optimal conditions, the linear dynamic range and RSD were found to be 0.01–10.0 mg L^?1 and 2.78% (n?=?3), respectively. A limit of detection of 0.005 mg L^?1 was obtained for the determination of bisphenol A. The obtained results showed successful application of the method for the analysis of bisphenol A in real samples.     

Gold Nanoparticle-Based Fluorescence Resonance Energy Transfer Aptasensor for Ochratoxin A Detection

In this paper, a sensitive and specific fluorescence resonance energy transfer (FRET) aptasensor for the detection of Ochratoxin A (OTA) was developed based on a dye-tagged ssDNA hybridized with aptamer-conjugated Au nanoparticles (Au NPs). The binding between the aptamer-Au NPs conjugate and the dye-labeled ssDNA leads to the fluorescence quenching of FAM due to its close proximity. The addition of OTA results in fluorescence recovery, attributed to the formation of a quadruplex-OTA complex, which detaches from the surface of Au NPs. Under optimal conditions, the relative fluorescence intensity (ΔI) is proportional to the concentration of the OTA in the range of 5 × 10^?12 to 5 × 10^?9 g/mL, with a detection limit of 2 × 10^?12 g/mL. The proposed method was successfully applied to measure the concentration of OTA in naturally contaminated maize samples and validated using a commercially available enzyme-linked immunosorbent assay (ELISA) method. This work demonstrates that the combination of an aptamer that has a high binding affinity for the analyte with highly sensitive Au NPs that undergo FRET is a promising approach for the detection of small molecule toxins.     

Colorimetric detection of lead (II) based on silver nanoparticles capped with iminodiacetic acid

We report on a colorimetric probe for the determination of Pb(II). It is based on the use of silver nanoparticles that have been functionalizd with iminodiacetic acid (IDA-Ag NPs). The absorption spectrum and solution color of IDA-Ag NPs undergo dramatic changes on exposure to Pb(II) with a new absorption peak appearing at 650 nm and a concomitant color change from yellow to green. This is assumed to result from the aggregation of IDA-Ag NPs induced by Pb(II). Under optimum conditions, there is a linear relationship between the ratio of the absorbances at 650 and 396 nm, respectively, and the concentration of Pb(II) in the 0.4 to 8.0 μM concentration range, with a detection limit of 13 nM. The method was applied to the determination of Pb(II) in tap water and urea samples, and recoveries ranged from 93.7 % to 98.6 %.

Effects of pluronic silica nanoparticles on the photophysical and photodynamic therapy behavior of triphenyl-p-phenoxy benzoic acid metalloporphyrins

5, 10, 15, Triphenyl-20-p-phenoxy benzoic acid porphyrins (P) containing Zn (ZnP), Ga (GaP), and Si (SiP) were synthesized and conjugated to pluronic-silica (PluS) nanoparticles (NPs) where the fluorescence and singlet oxygen generating behavior of the porphyrins were investigated. The highest singlet oxygen quantum yield (Φ_Δ) was obtained for ZnP. When the porphyrins were conjugated to the PluS NPs, the Φ_Δ was quenched and fluorescence was enhanced. The pore size of the NPs upon conjugation decreased from 18.9 nm for PluS NPs to 2.4 nm (for ZnP as an example) as determined by applying the Brunauer–Emmett–Teller method. The porphyrin complexes and their conjugates were tested for their photodynamic therapy (PDT) activity on MCF-7 breast cancer cells. It was found that ZnP and its conjugate showed the highest PDT activity. The p > 0.05 indicated that ZnP is significantly different than GaP and SiP.     

Antibacterial activity of glutathione-coated silver nanoparticles against Gram positive and Gram negative bacteria

In the present paper, we study the mechanism of antibacterial activity of glutathione (GSH) coated silver nanoparticles (Ag NPs) on model Gram negative and Gram positive bacterial strains. Interference in bacterial cell replication is observed for both cellular strains when exposed to GSH stabilized colloidal silver in solution, and microbicidal activity was studied when GSH coated Ag NPs are (i) dispersed in colloidal suspensions or (ii) grafted on thiol-functionalized glass surfaces. The obtained results confirm that the effect of dispersed GSH capped Ag NPs (GSH Ag NPs) on Escherichia coli is more intense because it can be associated with the penetration of the colloid into the cytoplasm, with the subsequent local interaction of silver with cell components causing damages to the cells. Conversely, for Staphylococcus aureus, since the thick peptidoglycan layer of the cell wall prevents the penetration of the NPs inside the cytoplasm, the antimicrobial effect is limited and seems related to the interaction with the bacterial surfaces. Experiments on GSH Ag NPs grafted on glass allowed us to elucidate more precisely the antibacterial mechanism, showing that the action is reduced because of GSH coating and the limitation of the translational freedom of NPs.