Environmental synthesis of silver nanoparticles using hydroxypropyl starch and their characterization

Antidiabetic assessment; in vivo study of gold and core-shell silver-gold nanoparticles on streptozotocin-induced diabetic rats

Recently, we have published a pioneering work on green biosynthesis and complete characterization of gold and core shell silver-gold nanoparticles (AuNPs and Ag@AuNPs). Herein, the so obtained nanoparticles are assessed for their antidiabetic activity in streptozotocin-induced diabetic rats. Thus, sixty-four male albino rats were divided into eight groups: control untreated; diabetic rats; diabetic rats received standard drug; diabetic rats received carrier only; diabetic rats received 0.5ml AuNPs; diabetic rats received 1ml AuNPs; diabetic rats received 0.5ml Ag@AuNPs and diabetic rats received 1ml Ag@AuNPs for twenty-one days. Results revealed that diabetic rats treated with AuNPs or Ag@AuNPs restored normal glucose level. In particular, Ag@AuNPs was found to significantly induce a reduction in blood glucose and restore both the high serum insulin level and glucokinase activity compared to the control normal rats. The results obtained disclose the effectual role of Ag@AuNPs in reducing the lipid profile, an anti-inflammatory effect in diabetic rats assessed using inflammatory markers IL-α and C-reactive protein (CRP). Histopathological examination of diabetic rats signifies distortion in the arrangement of cells around the central vein, inflammatory cells, pyknotic and apoptotic nuclei. Kidney of diabetic rat appears with vacuolation and pyknotic nuclei of some tubules. On the other hand, the liver of diabetic rat treated with Ag@AuNPs displayed normal hepatic cells with only few necrosis of hepatocytes. Ag@AuNPs restored the increased number of caspase-3 stained cells in the liver and kidney tissue in diabetic rats. In conclusion, Ag@AuNPs was observed to improve diabetic condition by limiting prolonged inflammation, suppressing oxidative stress and elevating the antioxidant defense system in diabetic rats which subsequently evoke the potential impact of AuNPs as a cost effective therapeutic cure in diabetic treatments and its complications.

Antibacterial activity of silver nanoparticles synthesized In-situ by solution spraying onto cellulose

Spray technique was used for the adsorption of in-situ silver nanoparticles (AgNPs) onto and inside the surface of nano- and micro- fibrillar cellulose (NFC and MFC) as well as filter paper. The abundance of hydroxyl and carboxyl groups located in NFC and MFC are used to stabilize Ag ions (Ag(+)) which were then in-situ reduced to (AgNPs) by chemical or UV reduction. The surface characteristic features, elemental analysis, particle size as well as size distribution of the obtained MFC, NFC and filter paper loaded with AgNPs were characterized via field emission scanning electron microscopy connected to energy dispersive X-ray spectroscopy (FESEM- EDX) and transmission electron microscopy (TEM). The associated chemical changes after growth of AgNPs onto the cellulose substrates were assessed by fourier transform infra-red (FT-IR) while the thermal stability of such systems were investigated by thermogravimetrical analyses (TGA). The antibacterial properties of AgNPs loaded NFC, MFC and filter paper as well was investigated against Escherichia Coli. The resulted data indicate that the particle size was found to be 11 and 26nm for AgNPs nucleated on NFC and MFC-based papers respectively. The antibacterial activity of AgNPs loaded MFC exhibited higher antibacterial activity than that of AgNPs loaded NFC. Overall, the present research demonstrates facile and fast method for in-situ antibacterial AgNPs loading on cellulose substrates.

Reversible encapsulation of silver nanoparticles into the helix of amylose (water soluble starch)

Natural biodegradable polymeric starch capped Ag-nanoparticles (AgNPs) were prepared by using extract of Dioscorea deltoidea in the presence of starch.

Novel antibacterial electrospun materials based on polyelectrolyte complexes of a quaternized chitosan derivative

Novel antibacterial materials based on polyelectrolyte complexes of quaternized chitosan (TMCh) and poly(2-acrylamido-2-methylpropanesulfonic acid) or poly(acrylic acid) (PAA) were prepared by electrospinning. AgNPs were loaded in TMCh/PAA fibers.

Facile Precursor for Synthesis of Silver Nanoparticles Using Alkali Treated Maize Starch

Silver nanoparticles were prepared by using alkali treated maize starch which plays a dual role as reducer for AgNO3 and stabilizer for the produced AgNPs. The redox reaction which takes a place between AgNO3 and alkali treated starch was followed up and controlled in order to obtain spherical shaped silver nanoparticles with mean size 4-6 nm. The redox potentials confirmed the principle role of alkali treatment in increasing the reducibility of starch macromolecules. The measurements of reducing sugars at the end of reaction using dinitrosalicylic acid reagent (DNS) were carried out in order to control the chemical reduction reaction. The UV/Vis spectra show that an absorption peak, occurring due to surface plasmon resonance (SPR), exists at 410 nm, which is characteristic to yellow color of silver nanoparticles solution. The samples have been characterized by transmission electron microscopy (TEM), which reveal the nanonature of the particles.

One Step Photopolymerization of N, N-Methylene Diacrylamide and Photocuring of Carboxymethyl Starch-Silver Nanoparticles onto Cotton Fabrics for Durable Antibacterial Finishing

The PI/UV system ((4-trimethyl ammonium methyl) benzophenone chloride/UV) was used to synthesize carboxymethyl starch- (CMS-) stabilized silver nanoparticles (AgNPs). AgNPs so prepared had round shape morphology with size of 1–7 nm. The prepared AgNPs were utilized to impart antibacterial finishing for cotton fabrics. The PI/UV system was further utilized to fix AgNPs onto cotton fabrics by photocrosslinking of AgNPs-CMS composite onto cotton fabrics to impart durable antibacterial properties. Effect of irradiation time and incorporating N, N-methylene diacrylamide (MDA) in different concentrations on antibacterial performance before and after repeated washing cycles was studied. S. aureus and E. coli were used to evaluate the antibacterial performance of finished fabrics. The antibacterial performance was directly proportional to the irradiation time and concentration of MDA but inversely proportional to the number of washing cycles. The inhibition zone of S. aureus and E. coli is the same although they are different in the cell wall structure and mode of action due to the nanosize structure formed.

Electrospun chitosan nanofibers with controlled levels of silver nanoparticles. Preparation, characterization and antibacterial activity

The ideal wound dressing would have properties that allow for absorption of exudates, and inhibition of microorganism for wound protection. In this study, we utilized an electrospinning (ELSP) technique to design a novel wound dressing. Chitosan (CTS) nanofibers containing various ratios of silver nanoparticles (AgNPs) were obtained. AgNPs were generated directly in the CTS solution by using a chemical reduction method. The formation and presence of AgNPs in the CTS/AgNPs composite was confirmed by x-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV) and thermogravimetric analysis (TGA). The electrospun CTS/AgNPs nanofibers were characterized morphologically by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These nanofibers were subsequently tested to evaluate their antibacterial activity against gram-negative Pseudomonas aeruginosa (P. aeruginosa) and gram-positive Methicillin-resistant Staphylococcus aureus (MRSA). Results of this antibacterial testing suggest that CTS/AgNPs nanofibers may be effective in topical antibacterial treatment in wound care.

A novel photosynthesis of carboxymethyl starch-stabilized silver nanoparticles

The water soluble photoinitiator (PI) 4-(trimethyl ammonium methyl) benzophenone chloride is used for the first time in the synthesis of silver nanoparticles (AgNPs). A new green synthesis method involves using PI/UV system, carboxymethyl starch (CMS), silver nitrate, and water. A mechanism of the reduction of silver ions to AgNPs by PI/UV system as well as by the newly born aldehydic groups was proposed. The synthesis process was assessed by UV-vis spectra and TEM of AgNPs colloidal solution. The highest absorbance was obtained using CMS, PI and AgNO3 concentrations of 10 g/L, 1 g/L, and 1 g/L, respectively; 40 °C; 60 min; pH 7; and a material : liquor ratio 1 : 20. AgNPs so-obtained were stable in aqueous solution over a period of three weeks at room temperature (~25 °C) and have round shape morphology. The sizes of synthesized AgNPs were in the range of 1-21 nm and the highest counts % of these particles were for particles of 6-10 and 1-3 nm, respectively.

Preparation, characterization and cytotoxicity of schizophyllan/silver nanoparticle composite

Silver nanoparticles (Ag-NPs) have been successfully prepared with a simple and "green" chemical reduction method. Triple helical schizophyllan (SPG) was used for the first time as reducing and stabilizing agents. The effect of temperature, silver nitrate/schizophyllan concentrations, pH of the reactions medium and the reaction time were investigated. The obtained schizophyllan/Ag-NP was characterized by UV-vis spectroscopy, TEM, DLS, X-ray diffraction, TGA, and ATR-FTIR. The results revealed that, Ag-NPs attached to SPG through a strong non-covalent interaction, leading to good dispersion of Ag-NPs with a diameter of 6 nm within the biopolymer matrix. By increasing the pH of the reaction medium, the triple helical structure of SPG was partially broken. The SPG/AgNP nanocomposite was non-toxic for mouse fibroblast line (NIH-3T3) and human keratinocyte cell line (HaCaT).

Synthesis, characterization and catalytic activity of silver nanoparticles using Tribulus terrestris leaf extract

Biomediated silver nanoparticles were synthesized with the aid of an eco-friendly biomaterial, namely, aqueous Tribulus terrestris extract. Silver nanoparticles were synthesized using a rapid, single step, and completely green biosynthetic method employing aqueous T. terrestris leaf extracts as both the reducing and capping agent. Silver ions were rapidly reduced by aqueous T. terrestris leaf extracts, leading to the formation of highly crystalline silver nanoparticles. An attempt has been made and formation of the silver nanoparticles was verified by surface plasmon spectra using an UV-vis (Ultra violet), spectrophotometer. Morphology and crystalline structure of the prepared silver nanoparticles were characterized by TEM (Transmission Electron Microscope) and XRD (X-ray Diffraction), techniques, respectively. FT-IR (Fourier Transform Infrared), analysis suggests that the obtained silver nanoparticles might be stabilized through the interactions of carboxylic groups, carbonyl groups and the flavonoids present in the T. terrestris extract.

Photosynthesis of Carboxymethyl Starch-Stabilized Silver Nanoparticles and Utilization to Impart Antibacterial Finishing for Wool and Acrylic Fabrics

The water soluble photoinitiator (PI) 4-(trimethyl ammonium methyl) benzophenone chloride/UV system is used in the synthesis of silver nanoparticles (AgNPs). Green synthesis method involved using PI/UV system, carboxymethyl starch (CMS), silver nitrate, and water. AgNPs obtained had a spherical shape morphology and a size of 1–7 nm. To impart antibacterial properties, wool and acrylic fabrics were treated with AgNPs obtained. The PI/UV system was further utilized to fix AgNPs onto wool and acrylic fabrics by photocrosslinking to impart durable antibacterial properties. The effect of irradiation time on the antibacterial performance before and after repeated washing cycles was studied. S. aureus (as G +ve) and E. coli (as G −ve) were used to estimate the antibacterial performance of the finished fabrics. The antibacterial performance was directly proportional to the irradiation time but inversely proportional to the number of washing cycles. However, after the 15th washing cycle, samples still have bacteriostatic effect; that is, although they show zero inhibition zone, they cannot be attacked by the bacterial growth and do not inhibit the bacterial growth. AgNPs finished wool fabrics showed more antibacterial activity than those of AgNPs finished acrylic fabrics.

Green Synthesis of Hydroxyethyl Cellulose-Stabilized Silver Nanoparticles

Green synthesis aims to minimize the use of unsafe reactants and maximize the efficiency of synthesis process. These could be achieved by using environmentally compassionate polymers and nontoxic chemicals. Hydroxyethyl cellulose (HEC), an ecofriendly polymer, was used as both reducing and stabilizing agents in the synthesis of stable silver nanoparticles, while silver nitrate was used as a precursor and water as a solvent. The formation of silver nanoparticles was assessed by monitoring UV-vis spectra of the silver colloidal solution. The size of the nanoparticles was measured using transmission electron microscope (TEM). Reaction kinetics was followed by measuring the absorbance of silver colloidal solution at different time intervals. Optimum reaction conditions revealed that the highest absorbance was obtained using HEC : AgNO3 of 1.5 : 0.17 (g/100 cm3) at 70°C for 120 min at pH 12. The Ag0 nanoparticles colloidal solution so obtained (1000 ppm) were found stable in aqueous solution over a period of six months at room temperature (°C). The sizes of these nanoparticles were found in the range of 11–60 nm after six months of storing. FTIR spectra confirmed the interaction of both the aldehyde and OH groups in the synthesis and stabilization of silver nanoparticles.

Nanostructural Features of Silver Nanoparticles Powder Synthesized through Concurrent Formation of the Nanosized Particles of Both Starch and Silver

Green innovative strategy was developed to accomplish silver nanoparticles formation of starch-silver nanoparticles (St-AgNPs) in the powder form. Thus, St-AgNPs were synthesized through concurrent formation of the nanosized particles of both starch and silver. The alkali dissolved starch acts as reducing agent for silver ions and as stabilizing agent for the formed AgNPs. The chemical reduction process occurred in water bath under high-speed homogenizer. After completion of the reaction, the colloidal solution of AgNPs coated with alkali dissolved starch was cooled and precipitated using ethanol. The powder precipitate was collected by centrifugation, then washed, and dried; St-AgNPs powder was characterized using state-of-the-art facilities including UV-vis spectroscopy, Transmission Electron Microscopy (TEM), particle size analyzer (PS), Polydispersity index (PdI), Zeta potential (ZP), XRD, FT-IR, EDX, and TGA. TEM and XRD indicate that the average size of pure AgNPs does not exceed 20 nm with spherical shape and high concentration of AgNPs (30000 ppm). The results obtained from TGA indicates that the higher thermal stability of starch coated AgNPS than that of starch nanoparticles alone. In addition to the data obtained from EDX which reveals the presence of AgNPs and the data obtained from particle size analyzer and zeta potential determination indicate that the good uniformity and the highly stability of St-AgNPs).

Green synthesis of silver nanoparticles through reduction with Solanum xanthocarpum L. berry extract: characterization, antimicrobial and urease inhibitory activities against Helicobacter pylori

A green synthesis route for the production of silver nanoparticles using methanol extract from Solanum xanthocarpum berry (SXE) is reported in the present investigation. Silver nanoparticles (AgNps), having a surface plasmon resonance (SPR) band centered at 406 nm, were synthesized by reacting SXE (as capping as well as reducing agent) with AgNO(3) during a 25 min process at 45 °C. The synthesized AgNps were characterized using UV-Visible spectrophotometry, powdered X-ray diffraction, and transmission electron microscopy (TEM). The results showed that the time of reaction, temperature and volume ratio of SXE to AgNO(3) could accelerate the reduction rate of Ag(+) and affect the AgNps size and shape. The nanoparticles were found to be about 10 nm in size, mono-dispersed in nature, and spherical in shape. In vitro anti-Helicobacter pylori activity of synthesized AgNps was tested against 34 clinical isolates and two reference strains of Helicobacter pylori by the agar dilution method and compared with AgNO(3) and four standard drugs, namely amoxicillin (AMX), clarithromycin (CLA), metronidazole (MNZ) and tetracycline (TET), being used in anti-H. pylori therapy. Typical AgNps sample (S1) effectively inhibited the growth of H. pylori, indicating a stronger anti-H. pylori activity than that of AgNO(3) or MNZ, being almost equally potent to TET and less potent than AMX and CLA. AgNps under study were found to be equally efficient against the antibiotic-resistant and antibiotic-susceptible strains of H. pylori. Besides, in the H. pylori urease inhibitory assay, S1 also exhibited a significant inhibition. Lineweaver-Burk plots revealed that the mechanism of inhibition was noncompetitive.

Green synthesis of silver nanoparticles by a novel method: comparative study of their properties

This study presents a novel green method using starch for the synthesis of silver nanoparticles (AgNPs). In this method, the fungal supernatant was added to a mixture of starch and silver nitrate solutions. The characteristics of AgNPs synthesized by three independent processes-a modified polysaccharide method, a microbial method, and our novel method-were compared. Dynamic light scattering (DLS) analysis revealed that the average sizes of AgNPs synthesized by the microbial method, the modified polysaccharide method, and our novel method were 84, 20, and 15 nm, respectively. The most stable AgNPs were generated by our novel method. The X-ray diffraction (XRD) spectrum of the products from the novel method showed that these AgNPs have high crystallinity. Fourier-transform infrared spectroscopy (FTIR) spectra demonstrated that the functional groups present in the products prepared by the novel method are a combination of the functional groups present in the AgNPs synthesized by the other two methods.