Effect of sunlight on the preparation and properties of cellulose/silver nanoparticle composite films by in situ method using Ocimum sanctum leaf extract as a reducing agent

Cellulose/silver nanoparticle composite films with in situ-generated silver nanoparticles (AgNPs) were prepared using Ocimum sanctum leaf extract as a reducing agent in the absence and presence of sunlight and were characterized by SEM, FTIR, XRD, and antibacterial tests. Sunlight hastened up the preparation of these composite films. The average size of the in situ-generated AgNPs was reduced by the sunlight. The antibacterial activity and other properties of the composites were enhanced by the sunlight. The cellulose/AgNP composite films with improved properties by sunlight can be considered for medical purpose as antibacterial dressing materials.     

Modification of natural fibers from Thespesia lampas plant by in situ generation of silver nanoparticles in single-step hydrothermal method

Ligno-cellulosic fibers have a great market and propose higher value addition and options to develop various products but they do not have inherent antimicrobial properties. In this study, a simple hydrothermal method was applied to build up antimicrobial properties to natural fibers by in situ-generating silver nanoparticles (AgNPs) in them. Herein, the ligno-cellulosic Thespesia lampas natural fibers were selected to develop antimicrobial activity using silver nitrate (AgNO₃) solution by hydrothermal method. The modified fibers were characterized by SEM, FTIR, XRD, TGA, and antibacterial activity tests. The modified fibers had spherical AgNPs with an average size of 95?nm. The thermal stability of the modified fibers was higher than that of the unmodified fibers. The modified fibers exhibited good antibacterial activity against both the Gram negative and Gram positive bacteria. These modified fibers can be considered as fillers in polymer matrices to make antibacterial composites.     

Preparation and properties of silver nanocomposite fabrics with in situ-generated silver nano particles using red sanders powder extract as reducing agent

Nanocomposite cotton fabrics with in situ-generated silver nanoparticles (AgNPs) were prepared by using Pterocarpus santalinus (Red sanders) extract in water as a reducing agent. The formation of AgNPs was analyzed by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy. The SEM analysis of nanocomposites showed the presence of spherical AgNPs with a size range of 71–90?nm. FTIR spectra showed the involvement of hydroxyl and methylene groups of cellulose matrix in reducing the silver salt into AgNPs in the presence of red sanders powder extract as reducing agent for the in situ generation of AgNPs. These nanocomposite fabrics exhibited good antibacterial activity against Gram positive and Gram negative bacteria.     

Antibacterial cotton fabrics with in situ generated silver and copper bimetallic nanoparticles using red sanders powder extract as reducing agent

Using aqueous extraction of red sanders powder as a reducing agent, silver and copper bimetallic nanoparticles were in situ generated in cotton fabrics. Silver and copper nanoparticles were also generated separately for comparison. The resulted nanocomposite cotton fabrics (NCFs) were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and antibacterial tests. SEM analysis indicated the generation of more number of nanoparticles when bimetallic source solutions were used. Further, the size range of the generated bimetallic nanoparticles was found to be lower than when individual metal nanoparticles were generated in NCFs. XRD analysis confirmed the in situ generation of silver and copper nanoparticles when equimolar bimetallic salt source solutions were utilized. The NCFs with bimetallic nanoparticles exhibited higher antibacterial activity against both Gram-negative and Gram-positive bacteria and hence can be considered for applications as antibacterial bed and dressing materials.     

In situ generation of silver nanoparticles in cellulose matrix using Azadirachta indica leaf extract as a reducing agent

In the present work, silver nanoparticles (AgNPs) were in situ generated in cellulose matrix using leaf extract of Azadirachta indica as a reducing agent. The cellulose/AgNP composite films prepared were characterized by FTIR, X-ray diffraction (XRD), scanning electron microscope, and antibacterial tests. The infrared spectra indicated the association of organic materials with silver nanoparticles to serve as capping agents. Scanning electron micrographs showed that synthesized silver nanoparticles were nearly uniform and spherical in shape with diameter in the range of 61–110?nm. XRD confirmed the formation of AgNPs and Ag–O nanoparticles. The nanocomposite films showed good antibacterial activity against Escherichia coli bacteria.     

Development and analysis of cellulose nanocomposite films with in situ generated silver nanoparticles using tamarind nut powder as a reducing agent

Cellulose/Tamarind nut powder (TNP)/Silver nanoparticles (AgNPs) nanocomposites were prepared by in situ generation of AgNPs using regeneration method, followed by solution casting method. In this, TNP was used as a reducing agent. These nanocomposites were characterized using FT-IR spectroscopy, XRD and SEM and studied their mechanical properties and antibacterial activity for medical and packing applications. The FT-IR spectral studies revealed the involvement of functional groups – Polyphenols, Flavonoids and –OH in the process of reducing the metal salts into metal nanoparticles. These nanocomposites showed good antibacterial activity against five bacteria. Improved mechanical properties with good antibacterial activities make these composites suitable for medical, food and packaging applications.     

Synthesis of Silver Nanoparticles from Extracts of Wild Ginger (Zingiber zerumbet) with Antibacterial Activity against Selective Multidrug Resistant Oral Bacteria

Antibiotic resistance rate is rising worldwide. Silver nanoparticles (AgNPs) are potent for fighting antimicrobial resistance (AMR), independently or synergistically. The purpose of this study was to prepare AgNPs using wild ginger extracts and to evaluate the antibacterial efficacy of these AgNPs against multidrug-resistant (MDR) Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis. AgNPs were synthesized using wild ginger extracts at room temperature through different parameters for optimization, i.e., pH and variable molar concentration. Synthesis of AgNPs was confirmed by UV/visible spectroscopy and further characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy analysis (EDXA), and Fourier-transform infrared spectroscopy (FTIR). Disc and agar well diffusion techniques were utilized to determine the in vitro antibacterial activity of plant extracts and AgNPs. The surface plasmon resonance peaks in absorption spectra for silver suspension showed the absorption maxima in the range of 400–420 nm. Functional biomolecules such as N–H, C–H, O–H, C–O, and C–O–C were present in Zingiber zerumbet (Z. zerumbet) (aqueous and organic extracts) responsible for the AgNP formation characterized by FTIR. The crystalline structure of ZZAE-AgCl-NPs and ZZEE-AgCl-NPs was displayed in the XRD analysis. SEM analysis revealed the surface morphology. The EDXA analysis also confirmed the element of silver. It was revealed that AgNPs were seemingly spherical in morphology. The biosynthesized AgNPs exhibited complete antibacterial activity against the tested MDR bacterial strains. This study indicates that AgNPs of wild ginger extracts exhibit potent antibacterial activity against MDR bacterial strains.     

Nanocomposite polyester fabrics with in situ generated silver nanoparticles using tamarind leaf extract reducing agent

Using tamarind leaf extract as a reducing agent and various concentrated aq?AgNO₃ solutions as source, the silver nanoparticles (AgNPs) were in situ generated in polyester fabrics. The nanocomposite polyester fabrics were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and antibacterial tests. The size of the generated AgNPs varied between 50 and 120?nm. The X-ray analysis indicated the generation of both AgNPs and AgO nanoparticles in the nanocomposite fabrics. The nanocomposite polyester fabrics exhibited excellent antibacterial activity against both the Gram negative and Gram positive bacteria and hence can be considered for making antibacterial textiles.     

Synthesis of Rumex hastatus-based silver nanoparticles induced the inhibition of human pathogenic bacterial strains

The development of antibiotic resistance in pathogenic bacterial strains has drawn attention to the quest for new natural antibacterial drugs. Therefore, in the present study, extracts of Rumex hastatus leaves were obtained in methanol and water, and R. hastatus-based silver nanoparticles (AgNPs) were synthesized. Structural and functional properties of synthesized silver nanoparticles were determined by UV–vis spectroscopy, XRD, FTIR and SEM. The synthesized AgNPs and crude extracts were tested to check their antibacterial potential against human pathogenic bacterial strains of Staphylococcus aureus, Staphylococcus haemoliticus, Bacillus cereus, Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa in well diffusion and broth dilution methods. The present investigation has revealed for the first time that the broth dilution method was found more reproducible than that of the well diffusion method even at lower concentrations of AgNPs and crude extracts. UV– Vis spectroscopic analysis of AgNPs revealed a peak at 367 nm_. XRD pattern showed a face-centered cubical to the spherical structure of AgNP crystals. FTIR analysis revealed that flavonoids and terpenoids are responsible for the reduction of AgNO₃ to Ag⁺. SEM analysis determined the spherical structure and 51 nm average diameter of nanoparticles. The antibacterial activity of R. hastatus-based (AgNPs) was found to be significantly higher than aqueous plant extract and silver nitrate alone. Bacterial growth was inhibited by R. hastatus-based AgNPs in a dose-dependent manner. To our knowledge, silver nanoparticles (AgNPs) of R. hastatus were synthesized and characterized for the first time in this study and, based on the findings of current research work R. hastatus extract-based silver nanoparticles are suggested to be used as an antibacterial drug instead of synthetic drugs for the treatment of various human diseases/infections caused by the tested bacterial strains.     

Tensile,thermal, and antibacterial characterization of composites of cellulose/modified Pennisetum purpureum natural fibers with in situ generated copper nanoparticles

Eco-friendly all cellulose composites were developed using cellulose as matrix and nanocomposite (in situ generated copper nanoparticles modified Napier Grass Fibers (NGFs)) as fillers for the antibacterial applications. The content of the nanocomposite filler was increased from 1?wt.% to 5?wt.% in the cellulose matrix. All these composites were characterized by Scanning Electron Microscopy (SEM), Tensile, Thermo Gravimetric Analysis (TGA), and antibacterial tests. SEM-EDX analysis revealed the in situ generation of copper nanoparticles on the surface of the films. Further, all cellulose composites showed good thermal stability. A minimum of 30% increase in char residue was observed in all cellulose nanocomposites compared to matrix. Antibacterial analysis indicated an excellent clear zone formation against both Gram Negative (Escherichia coli) and Gram Positive (Staphylococcus) bacteria. Hence, all these cellulose nanocomposite films can be considered as antibacterial packaging and dressing materials in medical field.     

Antibacterial and antioxidant properties of phyto-synthesized silver nanoparticles using Lavandula stoechas extract

Due to environmentally friendly and cost- effective issues, biological methods for silver nanoparticles (AgNPs) synthesis are advantageous over chemical and physical ones. In this study, AgNPs synthesized using Lavandula stoechas extract as a reductant and its antioxidant capacity, antibacterial property and cytotoxicity effect were investigated. The phyto-synthesized AgNPs were characterized using various analyses such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) as well as Fourier transform infrared (FT-IR). The prepared nanoparticles were spherical on shape with the size about 20–50 nm. Antibacterial studies through agar disk diffusion method confirmed the antibacterial potential of phyto-synthesized AgNPs toward two clinical Staphylococus aureus and Pseudomonas aeruginosa bacteria, although MTT assay demonstrated that S. aureus (MIC = 125 μg/ml) was more susceptible to AgNPs than P. aeruginosa (MIC = 250 μg/ml). Moreover, the cytotoxicity assay of phyto-synthezied AgNPs showed a low cytotoxic effect on RAW264 cell line at 62.5 μg/ml as an effective concentration. Also the considerable antioxidant capacity of the AgNPs confirmed through DPPH assay. Great antibacterial and antioxidant properties along with biocompatibility make the suggested phyto-synthesized AgNPs a great candidate for different biomedical applications including wound healing.     

Preparation and properties of low-cost cotton nanocomposite fabrics with in situ-generated copper nanoparticles by simple hydrothermal method

In this work, copper nanoparticles were in situ generated in cotton fabrics by simple hydrothermal method. These low-cost nanocomposite fabrics were characterized by scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, thermogravimetric analysis, and antibacterial tests. The presence of spherical nanoparticles was visualized by SEM analysis. FTIR spectra did not show any differences between the peak positions of cotton fabrics and their nanocomposites. The crystallinity of cotton nanocomposites was enhanced by the copper nanoparticles. The cotton nanocomposite fabrics exhibited good antibacterial activity against Escherichia coli bacteria and hence can be considered for medical applications such as wound dressing, surgical aprons, hospital bed materials, etc.     

Green Synthesis of Silver Nanoparticles by Extracellular Extracts from Aspergillus japonicus PJ01

The present study focuses on the biological synthesis, characterization, and antibacterial activities of silver nanoparticles (AgNPs) using extracellular extracts of Aspergillus japonicus PJ01.The optimal conditions of the synthesis process were: 10 mL of extracellular extracts, 1 mL of AgNO₃ (0.8 mol/L), 4 mL of NaOH solution (1.5 mol/L), 30 °C, and a reaction time of 1 min. The characterizations of AgNPs were tested by UV-visible spectrophotometry, zeta potential, scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric (TG) analyses. Fourier transform infrared spectroscopy (FTIR) analysis showed that Ag⁺ was reduced by the extracellular extracts, which consisted chiefly of soluble proteins and reducing sugars. In this work, AgNO₃ concentration played an important role in the physicochemical properties and antibacterial properties of AgNPs. Under the AgNO₃ concentration of 0.2 and 0.8 mol/L, the diameters of AgNPs were 3.8 ± 1.1 and 9.1 ± 2.9 nm, respectively. In addition, smaller-sized AgNPs showed higher antimicrobial properties, and the minimum inhibitory concentration (MIC) values against both E. coli and S. aureus were 0.32 mg/mL.     

Daphne mucronata-mediated phytosynthesis of silver nanoparticles and their novel biological applications,compatibility and toxicity studies

This contribution reports the biosynthesis of silver nanoparticles (AgNPs) using aqueous leaf extracts of D. mucronata and their diverse applications. Synthesized AgNPs were characterized using diverse techniques, i.e. UV, XRD, EDS, SEM, TEM, FTIR and TGA/DTA. These techniques confirmed the authenticity of the synthesized nanoparticles. The bimodulated AgNPs revealed the highest radical scavenging potential, i.e. 86.4% relative to plant extract at 600?μg/ml. Escherichia coli was found to be the most susceptible strain to AgNPs. Growth of vancomycin-resistant Staphylococcus aureus was also inhibited. Hemolytic activity revealed negligible hemolysis, indicating the biocompatible nature of biomodulated AgNPs. Furthermore, no mutagenic properties were shown by the biogenic AgNPs. Synthesized nanoparticles possessed promising insecticidal potential and had no phytotoxic activity. No haemagglutination was observed for biogenic AgNPs.     

Synthesis of carrageenan coated silver nanoparticles by an easy green method and their characterization and antimicrobial activities

The aim of the present work was to synthesize carrageenan coated silver nanoparticles (CA–AgNPs) using carrageenan as reducing and stabilizing agent. For this purpose, 10 mL of 0.35% (w/v) carrageenan solution was mixed with 10 mL AgNO₃ solution at different concentrations (1, 5 and 10 mM), and the resulting mixture was stirred at 100 °C at high speed for 2 h. The formation of CA–AgNPs was proven with the surface plasmon peaks observed at approximately 420 nm. The sizes and zeta potentials of CA–AgNPs were determined by Zeta-Sizer. Negative zeta potentials of CA–AgNPs indicated that the obtained AgNPs were stable. With scanning electron microscope (SEM) and transmission electron microscope analysis, it was seen that CA–AgNPs have spherical structure. According to the energy dispersion spectrometer analysis based on SEM images, it was observed that the samples were elementally composed of carbon, oxygen, sulfur, potassium and silver. The chemical structures of CA–AgNPs were determined by Fourier transform infrared spectroscopy, and it was proved that the carbonyl and OH groups of carrageenan were involved in formation and stabilizing of AgNPs, respectively. According to thermal gravimetric analysis, it has been observed that CA–AgNPs were thermally more stable than pure carrageenan. Antibacterial activity of CA–AgNPs against gram-positive and gram-negative bacteria was investigated with agar well diffusion and liquid test. It has been observed that CA–AgNPs synthesized with 1 mM AgNO₃ did not have an antibacterial activity on Escherichia coli and Staphylococcus aureus. Inhibition zones of varying diameters were observed in the 5 mM and 10 mM S-AgNPs groups. The synthesized CA–AgNPs (5 and 10 mM) have the capacity to be used in wound dressing materials or topical agents applied to burns and wounds due to their antibacterial effects and stability.

     

Aerva lanata flower extract mediated green synthesis of silver nanoparticles: Their characterization,in vitro antioxidants and antimicrobial investigations

The production of nanoparticles (NPs) using biological methods may lead to the enhancement of clean, non-hazardous, and environmentally acceptable procedures. With this context, in the present study silver nanoparticles (AgNPs) were synthesized using the flower extract of Aerva lanata (A. lanata). The following techniques, including UV–visible spectroscopy, XRD, Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR), are used to study the crystalline nature, size, shape, and elemental composition of the biosynthesized AgNPs, and antimicrobial applications of the NPs also studied. In UV–visible spectroscopy results a strong absorbance peak at 425 nm confirmed the AgNPs. The SEM results confirmed the spherical shape of the NPs and their average size of 45.05 nm. X-ray diffractometry XRD spectra confirmed the crystalline nature of the AgNPs. Against the DPPH (2,2-diphenyl-1-picrylhydrazyl), nitric oxide and superoxide radicals, Alf-AgNPs and ascorbic acid had significant scavenging effects at higher concentration of 250 μg/mL, exhibited 65.76 ± 0.41% and 86.42 ± 0.69%, 78.39 ± 0.49% and 72.72 ± 0.14% and 70.79 ± 0.87% and 72.79 ± 0.33% inhibition, respectively. As produced AgNPs had strong antibacterial and moderate antifungal activities against pathogenic test bacterial strains viz. Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli), and Klebsiella pneumonia (K. pneumonia) with the maximum zone of inhibition 15 ± 1.07 mm, 12 ± 0.96 mm, 14 ± 1.05 mm, and 15 ± 2.54 mm, respectively at maximum (75 μg/mL) concentration of AgNPs, and the zone of inhibition of fungal strains Aspergillus fumigatus (A. fumigatus) (9 ± 0.67 mm) and Candida albicans (C. albicans) (7 ± 0.75 mm) at 75 μg/mL. It was eventually concluded that the biosynthesized Alf-AgNPs showed promising antioxidant and antimicrobial agents with very low concentrations.     

Preparation,characterization, and antibacterial activity of composite material: Cotton fabric/hydrogel/silver nanoparticles

A new composite cotton fabric with hydrogel containing silver nanoparticles (AgNPs) has been synthesized by two steps, and simultaneous in situ synthesis of AgNPs under visible light irradiation has been performed. The influence of silver nitrate concentration upon the hydrogel and AgNP properties was studied by colorimetric analysis, scanning electron microscopy, and transmission electron microscopy. The antibacterial activities of the composite materials have been investigated against Acinetobacter johnsonii and Escherichia coli in agar medium and meat-peptone broth. The results showed high inhibition activity toward both test cultures which were better expressed against A. johnsonii.     

In situ intercalative polymerization of conducting polypyrrole/montmorillonite nanocomposites

Conducting polypyrrole (PPy)‐montmorillonite (MMT) clay nanocomposites have been synthesized by the in situ intercalative polymerization method. The PPy‐MMT nanocomposites are characterized by field‐emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), ultraviolet–visible (UV–vis) spectroscopy, thermogravimetric analysis (TGA), and Fourier‐transform infrared (FTIR) spectroscopy. XRD patterns show that after polymerization by the in situ intercalative method with ammonium persulfate and 1 M HCl, an increase in the basal spacing from 1.2 to 1.9 nm was observed, signifying that PPy is synthesized between the interlayer spaces of MMT. TEM and SEM micrographs suggest that the coexistence of intercalated MMT layers with the PPy macromolecules. FTIR reveals that there might be possible interfacial interactions present between the MMT clay and PPy matrix. The study also shows that the introduction of MMT clay results in thermal stability improvement of the PPy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2279–2285, 2008     

Green Synthesis of Silver Nanoparticles Using the Plant Extract of Acer oblongifolium and Study of Its Antibacterial and Antiproliferative Activity via Mathematical Approaches

In this study, the antibacterial and antifungal properties of silver nanoparticles synthesized with the aqueous plant extract of Acer oblongifolium leaves were defined using a simplistic, environmentally friendly, reliable, and cost-effective method. The aqueous plant extract of Acer oblongifolium, which served as a capping and reducing agent, was used to biosynthesize silver nanoparticles. UV visible spectroscopy, X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and scanning electron microscopy were used to analyze the biosynthesized Acer oblongifolium silver nanoparticles (AgNPs). Gram-positive bacteria (Bacillus paramycoides and Bacillus cereus) and Gram-negative bacteria (E. coli) were used to test the AgNPs’ antibacterial activity. The presence of different functional groups was determined by FTIR. The AgNPs were rod-like in shape. The nanoparticles were more toxic against Escherichia coli than both Bacillus cereus and Bacillus paramycoides. The AgNPs had IC₅₀ values of 6.22 and 9.43 and mg/mL on HeLa and MCF-7, respectively, proving their comparatively strong potency against MCF-7. This confirmed that silver nanoparticles had strong antibacterial activity and antiproliferative ability against MCF-7 and HeLa cell lines. The mathematical modeling revealed that the pure nanoparticle had a high heat-absorbing capacity compared to the mixed nanoparticle. This research demonstrated that the biosynthesized Acer oblongifolium AgNPs could be used as an antioxidant, antibacterial, and anticancer agent in the future.     

Study of Antibacterial and Anticancer Properties of bioAgNPs Synthesized Using Streptomyces sp. PBD-311B and the Application of bioAgNP-CNC/Alg as an Antibacterial Hydrogel Film against P. aeruginosa USM-AR2 and MRSA

Here, we report the extracellular biosynthesis of silver nanoparticles (AgNPs) and determination of their antibacterial and anticancer properties. We also explore the efficacy of bioAgNPs incorporated in cellulose nanocrystals (CNCs) and alginate (Alg) for the formation of an antibacterial hydrogel film. Streptomyces sp. PBD-311B was used for the biosynthesis of AgNPs. The synthesized bioAgNPs were characterized using UV-Vis spectroscopy, TEM, XRD, and FTIR analysis. Then, the bioAgNPs’ antibacterial and anticancer properties were determined using TEMA and cytotoxicity analysis. To form the antibacterial hydrogel film, bioAgNPs were mixed with a CNC and Alg solution and further characterized using FTIR analysis and a disc diffusion test. The average size of the synthesized bioAgNPs is around 69 ± 2 nm with a spherical shape. XRD analysis confirmed the formation of silver nanocrystals. FTIR analysis showed the presence of protein capping at the bioAgNP surface and could be attributed to the extracellular protein binding to bioAgNPs. The MIC value of bioAgNPs against P. aeruginosa USM-AR2 and MRSA was 6.25 mg/mL and 3.13 mg/mL, respectively. In addition, the bioAgNPs displayed cytotoxicity effects against cancer cells (DBTRG-0.5MG and MCF-7) and showed minimal effects against normal cells (SVG-p12 and MCF-10A), conferring selective toxicity. Interestingly, the bioAgNPs still exhibited inhibition activity when incorporated into CNC/Alg, which implies that the hydrogel film has antibacterial properties. It was also found that bioAgNP-CNC/Alg displayed a minimal or slow release of bioAgNPs owing to the intermolecular interaction and the hydrogel’s properties. Overall, bioAgNP-CNC/Alg is a promising antibacterial hydrogel film that showed inhibition against the pathogenic bacteria P. aeruginosa and MRSA and its application can be further evaluated for the inhibition of cancer cells. It showed benefits for surgical resection of a tumor to avoid post-operative wound infection and tumor recurrence at the surgical site.