Starch-stabilized Silver Nanoparticles Research Articles

Selective colorimetric detection of Cr(VI) using starch-stabilized silver nanoparticles and application for chromium speciation

The selective quantitation of Cr(VI) was developed through colorimetric detection using starch-stabilized silver nanoparticles (starch-AgNPs). The detection of Cr(VI) was based on oxidative degradation of starch-AgNPs as the reduction of UV-Vis signal and the distinctive color change from yellow to colorless of starch-AgNPs were observed. To achieve the highest sensitivity by this method, pH 3, and only 1 min were required for the determination of Cr(VI). For analytical performances, two linear ranges of 0–6 µM and 10–80 µM with limit of detection of 0.93 µM (48 µg/L) and 11.57 µM (0.60 mg/L) were obtained, respectively. The developed colorimetric method was combined with inductively coupled plasma optical emission spectroscopy (ICP-OES) for the speciation analysis of chromium. The concentration of Cr(III) was calculated by subtraction of Cr(VI) from the total chromium concentration determined by ICP-OES. A satisfactory accuracy and precision based on the AOAC guidelines also proved that this simple and rapid sensor was successfully applied for speciation of chromium in real water samples.

Structural characterization and stability study of green synthesized starch stabilized silver nanoparticles loaded with isoorientin

Isoorientin (Iso) is a natural flavonoid, the effect of metal nanoparticles loaded with it was unknown. In this study, silver nanoparticles (AgNPs) were synthesized by corn starch and sodium citrate with the green synthesis method, and the structural characterization and stability of AgNPs loaded with Iso (AgNPs-Iso) were examined by UV–vis spectroscopy and zetasizer. Results showed that AgNPs (65 ± 0.87 nm, spheres) successfully loaded with Iso (117 ± 2.13 nm, loading efficiency: 76.60%). There are no significant changes of the stability of AgNPs and AgNPs-Iso in pH 5–9 and 0–0.30 M of NaCl solution. AgNPs-Iso was more stable than AgNPs in the simulated gastrointestinal digestion in vitro. Furthermore, AgNPs-Iso showed the lower erythrocytes hemolysis ratio and cytotoxicity, and exhibited a notably inhibitive effect on α-glucosidase and pancreatic lipase. Therefore, this study could provide the basic support for the further development of highly stable and lowly cytotoxic AgNPs-Iso on Type II diabetes and obesity.

Detection of creatinine using silver nanoparticles on a poly(pyrrole) thin film-based surface plasmon resonance sensor

Surface plasmon resonance (SPR) technique is a great tool to investigate the binding of analyte to functionalized surfaces and the immobilization of biomolecules. Creatinine is one of the biomarkers for monitoring renal functions and making a diagnosis of kidney disease. Elevated creatinine levels in the human body signifies impaired kidney disease. In this work, we developed a new strategy for creatinine detection using starch stabilized silver nanoparticles (starch-AgNPs) on poly(pyrrole) (PPy) thin film using the SPR technique. The assay exhibited the obvious change from yellow to orange color of AgNPs solution in the presence of creatinine, showing good sensitivity due to the localized plasmon effect of AgNPs. Based on this effect, the change of SPR reflectivity in the Kretschmann configuration was enhanced by the adsorption of AgNPs in the presence of creatinine on the PPy film. The SPR reflectivity upon the injection of the mixed solution on the PPy thin film increased with increasing creatinine concentration in the linear range from 10 to 1000 μM. As a comparison, performances of the creatinine sensor with three SPR sensor systems, i.e. only PPy film, PPy film with AgNPs, and PPy film with aggregated AgNPs, were studied. The SPR sensor with aggregated AgNPs was improved approximately four times compared with the substrate without aggregated AgNPs, and the limit of the detection was 0.19 μM. The proposed method is potentially useful for clinical applications.

Application of Starch-Stabilized Silver Nanoparticles as a Colorimetric Sensor for Mercury(II) in 0.005 mol/L Nitric Acid

A sensitive and selective Hg2+optical sensor has been developed based on the redox interaction of Hg2+with starch-coated silver nanoparticles (AgNPs) in the presence of 0.005 mol L−1HNO3. The relative intensity of the localized surface plasmon absorption band of AgNPs at 406 nm is linearly dependent on the concentration of Hg2+with positive slope for the concentration range 0–12.5 μg L−1and negative slope for the concentration range 25–500 μg L−1. Experiments performed demonstrated that metal ions (Na+, K+, Mg2+, Ca2+, Pb2+, Cu2+, Zn2+, Cd2+, Fe3+, Co2+, and Ni2+) do not interfere under the same conditions, due to the absence of oxidative activity of these ions, which guarantees the high selectivity of the proposed optical sensor towards Hg2+. The limits of detection and quantification were found to be 0.9 µg L−1and 2.7 µg L−1, respectively, and relative standard deviations varied in the range 9–12% for Hg content from 0.9 to 12.5 μg L−1and 5–9% for Hg levels from 25 to 500 μg L−1. The method was validated by analysis of CRM Estuarine Water BCR505. A possible mechanism of interaction between AgNPs and Hg2+for both concentration ranges was proposed on the basis of UV-Vis, TEM, and SAED analyses.

Preparation, characterization and electrochemistry of Layer-by-Layer films of silver nanoparticles and silsesquioxane polymer

This paper describes the synthesis of starch-stabilized silver nanoparticles (AgNPs-St) for the development of electrochemical sensors. Layer-by-Layer (LbL) films were evaluated with the AgNPs-St, as polyanion, alternating with 3-n-propylpyridinium silsesquioxane chloride (SiPy+Cl−), as polycation, obtaining the (SiPy+Cl-/AgNPs-St)n where n is the bilayers number. UV–vis characterization of (SiPy+Cl−/AgNPs-St)n LbL films showed a linear increase of the absorbance of surface plasmon resonance band at 400nm with bilayers number. Atomic force microscopy revealed an increase in thickness of the (SiPy+Cl−/AgNPs-St)n LbL films from n=2 to n=10. These LbL films were employed for the electroanalytical determination of triiodide using the differential pulse voltammetry (DPV). The DPV parameters were optimized by 23 factorial design. Two linear ranges were found with detection limits of 5.56×10−6 and 1.51×10−5molL−1 and quantification limits 1.85×10−5 and 5.04×10−5molL−1.

Efficient Synthesis of (S)-(+)-Clopidogrel Bisulfate-Capped Silver Nanoparticles

In this work primarily one-pot synthetic development in the preparation of clopidogrel bisulfate with a polymorphic crystalline form II in 90% yield was developed. This premade antiplatelet drug has been used to protect starch-stabilized silver nanoparticles (AgNPs).

Rifampicin-loaded Silver-starch Nanocomposite for the Treatment of Multi-resistant Tuberculosis

Extraction, purification and synthesis of acetylated cassava starch was undertaken. The degree of modification for the acetylated (modified) starch was calculated to be 0.03. Physicochemical indices interrogated were all significantly (P<0.05) affected by the acetylation. Microstructural studies revealed starches that were predominantly polygonal in shape. The FTIR results confirmed introduction of an acetyl group with a new band at 1728 cm-1. The results further show that, the modification did not degrade the granule morphology, but x-ray pattern showed increased crystallinity in the acetylated derivative. Thermogravimetric analysis and differential scanning calorimetry revealed 2 phase decomposition of both starches and improved gelation capacity with new peaks respectively. Rifampicin (RIF) loaded starch-stabilized silver nanoparticles yielded good mean particle size (248 nm), polydispersity index (0.276) and zeta potential (18.68 mV). There was a significant (P<0.01) sustained release of RIF from the nano formulations up to 14.0 h. Antimicrobial susceptibility tests show that, the nano formulation exhibited good antimicrobial activity. It is therefore concluded that, acetylated cassava starch could be a good stabilizer and vehicle for drug delivery.

Separation of silver ions and starch modified silver nanoparticles using high performance liquid chromatography with ultraviolet and inductively coupled mass spectrometric detection

The production of commercially available products marketed to contain silver nanoparticles is rapidly increasing. Species-specific toxicity is a phenomenon associated with many elements, including silver, making it imperative to develop a method to identify and quantify the various forms of silver (namely, silver ions vs. silver nanoparticles) possibly present in these products. In this study a method was developed using high performance liquid chromatography (HPLC) with ultraviolet (UV–VIS) and inductively coupled mass spectrometric (ICP-MS) detection to separate starch stabilized silver nanoparticles (AgNPs) and silver ions (Ag+) by cation exchange chromatography with 0.5M nitric acid mobile phase. The silver nanoparticles and ions were baseline resolved with an ICP-MS response linear over four orders of magnitude, 0.04mgkg−1 detection limit, and 90% chromatographic recovery for silver solutions containing ions and starch stabilized silver nanoparticles smaller than 100nm.

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.

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.

Synthesis of Starch-Stabilized Silver Nanoparticles and Their Antimicrobial Activity

In this study, silver nanoparticles were prepared using silver nitrate as the metal precursor, starch as protecting agent, and sodium borohydride (NaBH4) as a reducing agent by the chemical reduction method. The formation of the silver nanoparticles was monitored using ultraviolet-visible absorption spectroscopy, cyclic voltammetry, and particle size analyzer and characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD). Synthesis of nanoparticles were carried out by varying different parameters, such as reaction temperature, concentration of reducing agent, concentration of silver ion in feed solution, type and concentration of the stabilizing agent, and stirrer speed expressed in terms of particle size and size distribution. Dispersion destabilization of colloidal nanoparticles was detected by Turbiscan. It was observed that size of the starch stabilized silver nanoparticles were lower than 10 nm. The microbial activity of synthesized silver nanoparticles was examined by modified Kirby-Bauer disk diffusion method. Silver nanoparticles were tested for their antibacterial activity against Gram negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, and Gram positive bacteria such as Staphylococcus aureus and Staphylococcus epidermidis. High bacterial activity was observed at very low concentrations of silver (below 1.39 μg/ml). The antifungal activity of silver nanoparticles has been assayed against Candida albicans.

Exploring a new rapid colorimetric detection method of Cu2+ with high sensitivity and selectivity

Abstract In this study, we propose a new rapid colorimetric detection method of Cu 2+ with high sensitivity and selectivity utilizing starch-stabilized silver nanoparticles (AgNPs), which are synthesized by a green chemistry way. AgNPs gradually become smaller in the presence of Cu 2+ due to redox reaction between Ag and Cu 2+ , which results in color change and UV–vis absorption decrease of the nanoparticle dispersion. Therefore, Cu 2+ could be recognized by visualizing the color change of AgNPs dispersed by naked eyes, and quantitatively measured by UV–vis spectra. There is a linear relationship between the absorbance ratio ( A 0 / A , at 400 nm) and the concentration of Cu 2+ ranging from 0.1 μM to 10 μM. The linear coefficient is 0.9968. The lowest detectable concentration is 0.5 μM by naked eyes. Furthermore, the selectivity of this detection system for Cu 2+ is excellent comparing with other metal ions, such as Hg 2+ , Co 2+ , Ba 2+ , Zn 2+ , Na + , Fe 3+ , Sr 2+ , Pb 2+ , Cd 2+ , Ni 2+ , Ca 2+ , Mg 2+ , Mn 2+ and K + . The high sensitivity and selectivity of the Cu 2+ detection system are ascribed to the unique redox reaction between Ag and Cu 2+ .

Preparation of starch-stabilized silver nanoparticles from amylose–sodium palmitate inclusion complexes

Starch-stabilized silver nanoparticles (AgNP) were prepared from amylose–sodium palmitate helical inclusion complexes by first converting sodium palmitate within the amylose helix to silver palmitate by an ion-exchange reaction with silver nitrate, and then reducing the complexed silver palmitate salt with NaBH4. This process yielded stable aqueous solutions that could be dried and then re-dispersed in water for end-use applications. Reaction products were characterized by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), UV–VIS spectroscopy, X-ray diffraction, TEM, SEM and light microscopy. Addition of acid to reduce the pH of aqueous starch-AgNP solutions produced an increase in viscosity, and nearly quantitative precipitation of starch-AgNP was observed at low pH. Smaller AgNP and higher conversions of silver nitrate to water-soluble starch-AgNP were obtained in this process, as compared with a process carried out under similar conditions using a commercial soluble starch as a stabilizer.

An investigation on the antibacterial, cytotoxic, and antibiofilm efficacy of starch-stabilized silver nanoparticles

The increased emergence of drug resistant microbes creates a major challenge to the scientific community for successful development of effective therapeutics. The antimicrobial activities of silver ions are well known, but limited information is available on the effects of green silver-nanoparticles (AgNPs) on human pathogens. In this article, we evaluated the antibacterial activity of starch-stabilized AgNPs against a panel of human pathogens commonly associated with air, water and food borne infections. The shape and size distribution of AgNPs were characterized by transmission electron microscopy. We showed that AgNPs were more effective against Gram-positive and Gram-negative pathogens as compared with acid-fast bacteria. AgNPs were not cytotoxic to macrophages at the bactericidal concentration and can augment intracellular killing potential of macrophages. Furthermore, we showed that AgNPs disrupt biofilm formation and exhibit better antibacterial activity compared to human cationic antimicrobial peptide LL-37. In summary, our data suggest AgNPs as a promising template for the design of novel antibacterial agents. From the Clinical EditorIn this fundamental study, the significance of starch-stabilized AgNP-s is studied as antimicrobial agents on a variety of human pathogens. AgNP-s are expected to become universally utilized agents in our efforts to prevent and fight infections.

Synthesis and characterization of fluorophore attached silver nanoparticles

Silver nanoparticles stabilized by soluble starch were synthesized and characterized. In vivo studies in rats showed no toxicity and revealed their distribution in various tissues and permeability across BBB. This starch stabilized silver nanoparticles have good biological characteristics to act as a potential promising vector for gene/drug delivery.

Green Synthesis of Starch-Stabilized Silver Nanoparticles and their Antibacterial Properties

Stable silver nanoparticles were synthesized from AgNO3through a simple green route using biodegradable and renewable starch as stabilizing agent. Nanoparticles have been studied for their formation, structure, morphology and size using UV–vis spectroscopy, X-ray diffraction (XRD) and HRTEM analysis. XRD showed that the nanoparticles were of face centered cubic structure. UV–Vis and HRTEM revealed that the spherical particles having radius 5-20 nm are mostly stabilized by starch. Further, antibacterial properties of these starch-stabilized nanoparticles show promising results for S.aureus in growth inhibition ring test.

Synthesis of starch-stabilized silver nanoparticles and their application as a surface plasmon resonance-based sensor of hydrogen peroxide

Stable and uniform starch-stabilized silver nanoparticles with average diameter 14.4 ± 3.3 nm are synthesized via green synthetic procedure, using ultrasound mediated reduction of silver nitrate by d-glucose. UV–vis spectroscopy, high-resolution transmission electron microscopy, X-ray diffraction, thermogravimetric/differential thermal analysis and differential scanning calorimetry are used to completely characterize the starch-stabilized silver nanoparticles. These nanoparticles exhibit a catalytic activity in the reduction of hydrogen peroxide (H 2O 2). The degradation of silver nanoparticles, induced by the catalytic decomposition of hydrogen peroxide, causes a considerable change in the absorbance strength of localized surface plasmon resonance band depending on the H 2O 2 concentration. The characterization and calibration of improvised plasmon resonance-based optical sensor is carried out. A good sensitivity and a linear response over the wide concentration range of 10 −1–10 −6 mol/L H 2O 2 is established. The quantification limit of this sensor is found to be 0.9 μM H 2O 2, which is lower than certain enzyme-based biosensors. Therefore, this optical sensor for hydrogen peroxide can be potentially applied in determination of other reactive oxygen species as well.

Preparation of starch stabilized silver nanoparticles with spatial self-phase modulation properties by laser ablation technique

Silver nanoparticles inside the starch solution have been successfully fabricated by laser ablation of a silver plate immersed in starch solution. The ablation has been done using a Q-switched Nd:YAG laser at 10 Hz repetition rate. The starch solution allows for the formation of silver nanoparticles with uniform particle diameters and well dispersed. The ablation was performed at different time durations to study the influence of the laser ablation time on efficiency of particle formation and sizes. The Spatial Self-phase modulation phenomena which can determine the nonlinear optical property of the samples were also investigated for starch solutions containing silver nanoparticles.

γ-Ray synthesis of starch-stabilized silver nanoparticles with antibacterial activities

Silver nanoparticles (Ag NPs) are fabricated through γ-irradiation reduction of silver ions in aqueous starch solutions. The UV–vis analyses show smaller sizes of Ag NPs produced, with higher yields, as the irradiation doses and/or Ag + concentrations are increased. Higher concentrations of starch enhance the yields of Ag NPs, with no significant effects on their size. The most economical Ag NPs are produced at 5 kGy γ-irradiation of a 2×10 −3 M solution of AgNO 3 containing 0.5% starch. They show a relatively narrow size distribution, indicated by TEM and its corresponding size distribution histogram. The XRD pattern confirms the face-centered cubic (fcc) Ag NPs embedded in starch molecules. Interactions between these nanoparticle surfaces and starch oxygen atoms are indicated by FT–IR. Antibacterial activities of Ag NPs against Escherichia coli appear dependent on the γ-ray doses applied.

Layer-by-Layer Assembly of Nacre-like Nanostructured Composites with Antimicrobial Properties

In a recent report, we have presented the layer-by-layer (LBL) assembly of a biomimetic nanostructured composite from Na(+)-montmorillonite clay nanosheets and poly(diallylmethylammonium chloride) (Tang, Z.; Kotov, N.; Magonov, S.; Ozturk, B. Nat. Mater. 2003, 2, 413). The structure, deformation mechanism, and mechanical properties of the material are very similar to those of natural nacre and lamellar bones. This fact prompts further investigation of these composites as potential bone implants. LBL assembly affords preparation of multifunctional composites, and here we demonstrate that not only mechanical strength, but also antibacterial activity, can be introduced in these implantable materials by alternating clay layers with starch-stabilized silver nanoparticles. The resulting composite showed excellent structural stability with no detectable levels of silver lost over a 1 month period. Evaluation of the antibacterial properties showed almost complete growth inhibition of E. coli over an 18 h period. The amount of silver eluted from the LBL composite over a 1 month period was determined to be only 0.5-3.0 microg/L. This concentration of silver did not prevent the growth of the mammalian tissue cultures. The LBL composite has shown biocompatibility with the human osteoblast cell line.