scholarly journals Synthesis Of PEG Coated Ascorbic Acid Functionalized Silver Nanoparticles and Determining its Antioxidant Activity

Silver nanoparticles are extensively being studied for various applications in different fields. Functionalized silver nanoparticles are now being used as drug carriers. Ascorbic acid (Vitamin C) is a well-known antioxidant which has been reported to have various beneficial properties to humans. Here we have synthesized silver nanoparticles functionalized with ascorbic acid. The functionalized nanoparticles were further coated with PEG. The nanoparticle synthesis was characterized using UV-Visible spectral analysis, XRD, FTIR and Scanning electron microscope. The average size of the nanoparticle was found to be 24 nm. The synthesized nanoparticle was found to possess antioxidative effects.

Author(s):  
Shyla Marjorie Haqq ◽  
Amit Chattree

  This review is based on the synthesis of silver nanoparticles (AgNPs) using a green approach which is biofabricated from various medicinal plants. AgNPs were prepared from the various parts of the plants such as the flowers, stems, leaves, and fruits. Various physiochemical characterizations were performed using the ultraviolet (UV)-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, transmission electron microscopy, and energy dispersive spectroscopy. AgNPs were also used to inhibit the growth of bacterial pathogens and were found to be effective against both the Gram-positive and Gram-negative bacteria. For the silver to have antimicrobial properties, it must be present in the ionized form. All the forms of silver-containing compounds with the observed antimicrobial properties are in one way or another source of silver ions. Although the antimicrobial properties of silver have been known, it is thought that the silver atoms bind to the thiol groups in enzymes and subsequently leads to the deactivation of enzymes. For the silver to have antimicrobial properties, it must be present in the ionized form. The study suggested that the action of the AgNPs on the microbial cells resulted into cell lysis and DNA damage. AgNPs have proved their candidature as a potential antibacterial against the multidrug-resistant microbes. The biological agents for synthesizing AgNPs cover compounds produced naturally in microbes and plants. Reaction parameters under which the AgNPs were being synthesized hold prominent impact on their size, shape, and application. Silver nanoparticle synthesis and their application are summarized and critically discussed in this review.


Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1486
Author(s):  
Ganesh Shimoga ◽  
Eun-Jae Shin ◽  
Sang-Youn Kim

Two xerogels made of 4-pyridyl cholesterol (PC) and silver-nanocomposites (SNCs) thereof have been studied for their efficient reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of aqueous sodium borohydride. Since in-situ silver doping will be effective in ethanol and acetone solvents with a PC gelator, two silver-loaded PC xerogels were prepared and successive SNCs were achieved by using an environmentally benign trisodium citrate dehydrate reducing agent. The formed PC xerogels and their SNCs were comprehensively investigated using different physico-chemical techniques, such as field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), powdered X-ray diffraction (XRD) and UV-Visible spectroscopy (UV-Vis). The FE-SEM results confirm that the shape of xerogel-covered silver nanoparticles (SNPs) are roughly spherical, with an average size in the range of 30–80 nm. Thermal degradation studies were analyzed via the sensitive graphical Broido’s method using a TGA technique. Both SNC-PC (SNC-PC-X1 and SNC-PC-X2) xerogels showed remarkable catalytic performances, with recyclable conversion efficiency of around 82% after the fourth consecutive run. The apparent rate constant (kapp) of SNC-PC-X1 and SNC-PC-X2 were found to be 6.120 × 10-3 sec-1 and 3.758 × 10-3 sec-1, respectively, at an ambient temperature.


2021 ◽  
Author(s):  
S Shanthi ◽  
V. Uma Maheshwari Nallal ◽  
Krishnan Anand ◽  
Balasubramani Ravindran ◽  
Soon Woong Chang ◽  
...  

Abstract Bio-inspired nanoparticle synthesis has attracted substantial interest among the scientific society owing to its eco-friendly and non-toxic nature. In the present study, Silver nanoparticles (AgNPs) were synthesized using high altitude squamulose lichen – Cladonia subradiata and characterized using different techniques. The antioxidant and anticandida activity of AgNPs were evaluated using multiple in-vitro assays. In-silico molecular docking analysis and in-vitro cytotoxic assay was performed to determine the anti-cancer potential of synthesized AgNPs. The results of the spectroscopic studies revealed the successful synthesis of AgNPs and the presence of different functional groups suggesting the involvement of phytocompounds in the reduction and capping of AgNPs. The average size of the AgNPs was 20 nm and predominantly spherical in shape. AgNPs demonstrated excellent DPPH free radicals scavenging activity with an IC50 value of 7.51 ± 0.4 µg/mL. C.albicans was identified as the most susceptible strain from the anticandida studies. Usnic acid and Pulvinic acid exhibited low binding energies and showed excellent inhibition interaction with EGFR lung cancer protein. The in-vitro cytotoxic results were impressive with an IC50 value of 28.75 µg/mL for A549 lung cancer cells treated with AgNPs. Thus, the study demonstrates the effective and non-toxic synthesis of AgNPs using a less explored lichen extract as a promising anticandida and anticancer agent in the field of nano-medicine.


2020 ◽  
Vol 21 (1) ◽  
pp. 30
Author(s):  
Dewi Mustika Rahim ◽  
Netti Herawati ◽  
Hasri Hasri

ABSTRAK Telah dilakukan penelitian tentang sintesis nanopartikel perak menggunakan bioreduktor ekstrak daun teh hijau (Camellia Sinensis) dengan iradiasi microwave. yang untuk mengetahui pengaruh waktu sintesis dan pengaruh pH stabilizer terhadap sintesis nanopartikel perak ekstrak daun teh hijau dengan iradiasi microwave serta karakterisasinya. Larutan AgNO3 3 mM direduksi menggunakan ekstrak daun teh hijau dan di iradiasi microwave pada variasi waktu sintesis 1-5 menit. Penentuan waktu sintesis optimal menggunakan spektrofotometer UV-Vis diukur setiap 1 menit. Nanopartikel dengan waktu sistesis 4 menit, pH stabilizer menggunakan asam sitrat dan NaOH dengan pH 6-9. Karakterisasi nanopartikel menggunakan instrumen SEM-EDS (Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy) dan PSA (Particle Size Analyzer). Hasil penelitian menunjukkan bahwa waktu sintesis optimal adalah 4 menit. Morfologi nanopatikel perak yang dikarakterisasi menggunakan SEM (Scanning Electron Microscopy) yang dihasilkan cenderung beragregasi. Adanya kecenderungan nanopartikel untuk beragregasi menyebabkan ukuran atau diameter nanopartikel tidak seragam. Ukuran dan distribusi ukuran nanopartikel perak dikarakterisasi menggunakan PSA(Particle Size Analyzer) dihasilkan pada pH 6 antara 31,01 – 402,44 nm dengan rata-rata ukuran sebesar 91 nm, pH 7 antara 35,03 – 740,899 nm dengan rata-rata ukuran sebesar 106,3 nm, pH 8 antara 39,58 – 193,48 nm dengan rata-rata ukuran 71,7, dan pH 9 antara 35,03 – 171,25 nm dengan rata-rata ukuran sebesar 64,4 nm. Disimpulkan bahwa hasil sintesis nanopartikel perak terkecil diperoleh pada pH 9 dan waktu sintesis 4 menit. Kata kunci: Ekstrak Daun Teh Hijau, Nanopartikel Perak, Iradiasi Microwave ABSTRACT Research has been carried out on the synthesis of silver nanoparticles using a bioreductor of green tea leaf extract (Camellia Sinensis) by irradiation microwave.This research aimed to determine the effect of synthesis time and pH stabilizer on the synthesis of silver nanoparticles of green tea leaf extract by microwave irradiation and it’s characterization. The 3 mM AgNO3 solution was reduced using green tea leaf extract and microwave irradiated in a variation of the synthesis time 1-5 minutes. The determining optimum of sythesis time was done by analysis of UV-Vis spectrum for every minutes. Nanoparticles with a synthesis time of 4 minutes, the stabilizer of silver nanoparticles used citric acid and NaOH with a pH of 6-9. Characterization of nanoparticles using SEM-EDS instrument (Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy) and PSA (Particle Size Analyzer). The results showed that the optimal synthesis time was 4 minutes. The morphology of silver nanopaticles characterized using SEM produced tends to aggregate. The tendency of nanoparticles to aggregate causes size or diameter of nanoparticles was random. The size and distribution of size silver nanoparticles characterized using PSA were produced at pH 6 between 31.01 - 402.44 nm with an average size of 91 nm, pH 7 between 35.03 - 740,899 nm with an average size amounting to 106.3 nm, pH 8 between 39.58 - 193.48 nm with an average size of 71.7, and pH 9 between 35.03 - 171.25 nm with an average size of 64.4 nm. It was concluded that the synthesis of the smallest silver nanoparticles was obtained at pH 9 and synthesis time of 4 minutes. Keywords: Green Tea Leaf Extract, Silver Nanoparticles, Microwave Irradiation


Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1295
Author(s):  
Shahid Ali ◽  
Muhammad Rahim ◽  
Perveen Fazil ◽  
Malik Shoaib Ahmad ◽  
Azeem Ullah ◽  
...  

The silver nanoparticles were synthesized, functionalized with afzelechin and characterized using UV-Visible spectroscopy. A difference of 20 nm was observed in surface plasmon resonance of bare and functionalized silver nanoparticles which indicates afzelechin conjugation with silver nanoparticles. The atomic force microscopy (AFM) technique was used for the determination of the size and morphology of synthesized silver nanoparticles. The afzelechin conjugated silver nanoparticles were spherical and their sizes ranged from 3 to 10 nm with an average size of 8 nm while the bare silver nanoparticles were also spherical and their sizes ranged from 3 to 10 nm with an average size of 6 nm. The average sizes were also calculated by fitting their UV-Visible absorption spectra. Fitting is based on the Mie and Mie Gans models, which deduced that afzelechin conjugated silver nanoparticles were 96.5% spherical and 3.5% spheroidal with an average size of 5 nm while bare silver nanoparticles were 100% spherical with an average size of 4 nm. Both the fitting model as well as the AFM results showed a difference of 3 nm between the sizes of afzelechin conjugated silver nanoparticles while 2 nm differences was observed for bare silver nanoparticles. The band gap energy of afzelechin conjugated silver nanoparticles and bare silver nanoparticles were calculated via Tauc’s equation and were found to be 5.1 eV and 5.4 eV, respectively. A difference of 0.3 eV was observed in band gap energies of afzelechin conjugated silver nanoparticles and bare silver nanoparticles.


2014 ◽  
Vol 13 (01) ◽  
pp. 1450004 ◽  
Author(s):  
Dharamvir Singh Ahlawat ◽  
Rekha Kumari ◽  
Rachna ◽  
Indu Yadav

Silver nanoparticles (SNPs) have been successfully prepared using sol–gel method by annealing the sample at 550°C for 30 min. The SNPs were not confirmed by X-ray diffraction (XRD) analysis when the annealing temperature was considered at 450°C. They were also not confirmed without calcination of the sample. The physical mechanism of silver clusters formation in the densified silica matrix with respect to thermal treatment has been understood. The presence of silver metal in the silica matrix was confirmed by XRD analysis and TEM image of the samples. The average size of nanoparticles dispersed in silica matrix was determined as 10.2 nm by the XRD technique. The synthesized nanocomposites were also characterized by UV-Visible spectroscopy with a peak in the absorption spectra at around 375 nm. The distribution of particle size has been reported here in the range from 8 nm to 25 nm by TEM observations of the sample prepared at 550°C. The spherically smaller size (≈10 nm) SNPs have reported the surface plasmons resonance (SPR) peak less than or near to 400 nm due to blue-shifting and effect of local refractive index. Without annealing the silica samples the absorption spectra does not show any peak around 375 nm. The FTIR spectroscopy of the three types of samples prepared at different temperatures (room temperature, 450°C and 550°C) has also been reported. This spectra have provided the identification of different chemical groups in the prepared samples. It has been predicted that the size of SNPs by XRD, UV-Visible and TEM results have agreed well with each other. It may be concluded that formation of SNPs is a function of annealing temperature.


2020 ◽  
Vol 71 (10) ◽  
pp. 50-57
Author(s):  
Kamran Mehdi ◽  
Wajid Rehman ◽  
Obaid-Ur-rahman Abid ◽  
Srosh Fazil ◽  
Muhammad Sajid ◽  
...  

The aim of the present study is to search out nontoxic silver nanoparticles synthesized from the leaf extract of two plants Ajuga parviflora Benth and Digera muricata for antimicrobial activity. The plants used in this investigation are rich in alkaloids, flavonoids, steroids, terpenoids, protein, amino acids, carbohydrate, quninones, phenols and tannins. The formation of nanoparticles were confirmed by UV/Visible spectroscopy, peaks at 423nm for Ajuga parviflora Benth and 408nm for Digera muricata. The morphology of the silver nanoparticles was established through state of the art spectroscopic tools. SEM analysis reveals average size of AgNPs 18 nm for Digera muricata and 22 nm for Ajuga parviflora Benth respectively while transmission electron microscopy confirms that AgNPs are spherical in shape. The synthesized nanoparticles were subjected to Escherichia coli, Staphylococcus aureus, Salmonella typhimurium and Pseudomonas aeruginosa. The results suggest that the silver nanoparticles have promising activity against all the bacterial strains and can be used an effective bactericides.


2015 ◽  
Vol 1086 ◽  
pp. 11-30 ◽  
Author(s):  
Chellasamy Panneerselvam ◽  
Kadarkarai Murugan ◽  
Duraisamy Amerasan

Metallic nanoparticles have received great attention from chemists, physicists, biologists and engineers who wish to use them for the development of a new generation of nanodevices. In the present Communication, a completely “green” chemistry method for producing silver nanoparticles is introduced. The process is simple, environmentally benign, and quite efficient. Green nanoparticle synthesis has been achieved using environmentally acceptable plant extract and ecofriendly reducing and capping agents. In particular, silver nanoparticles are proved to have potential antibacterial, antifungal and antiplasmodial and antimicrobial properties. The present study was aimed to identify the antiplasmodial activity of green synthesised silver nanoparticles (AgNPs) using aqueous extract of plantEuphorbia hirtaagainstP.falciparum. Nanoparticles are being used in many commercial applications. It was found that aqueous silver ions can be reduced by aqueous extract of plant to generate extremely stable silver nanoparticles in water. The bio-reduced silver nanoparticles were appropriately characterized by UV–vis spectrum, Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The formation of the AgNPs synthesized from the XRD spectrum compared with the standard confirmed spectrum of silver particles formed in the present experiments were in the form of nanocrystals, as evidenced by the peaks at 2θ values of =28.01°, 32.41°, 46.44°, 55.05° and 57.75°. The scanning electron micrograph (SEM) showed structures of spherical, cubic shape, and the size range was found to be 30–60 nm. The EDX spectra showed the purity of the material and the complete chemical composition of the synthesized AgNPs. The parasitic inhibition was dose-dependent. The synthesized AgNPs showed considerable antiplasmodial activity than the crude methanol and aqueous leaf extract ofE.hirta. The maximum efficacy was


2021 ◽  
Author(s):  
Esma Nur Gecer

Abstract Salvia aethiopis L. was heated in distilled water for 2 hours. After filtration, water extract was treated with silver nitrate for 2 hours at 60°C to yield the silver nanoparticles (Sa-AgNPs). The structure of silver nanoparticles was elucidated by spectroscopic methods such as Ultraviolet-visible (UV-Vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Scanning electron microscope (SEM). The maximum absorption in UV-Vis spectrum was observed at 508 nm. XRD pattern at (2θ) 38.1°, 44.3°, 64.4°, and 77.4° degrees can be assigned to the (111), (200), (220) and (311) Bragg’s reflections of the face-centered cubic crystalline structure. The average size of Sa-AgNPs was found as 74.09 nm by SEM analysis. The characteristic hydroxyl vibration signal appeared at 3222 cm− 1. Antioxidant activity of extract and Sa-AgNPs were carried out using DPPH•, ABTS•+ FRAP assay. The Sa-AgNPs revealed the considerable ABTS•+ scavenging effect with the value of 4.93 (IC50, µg/mL) compared to BHT (IC50, µg/mL, 8.34). However, Sa-AgNPs displayed the lower DPPH• activity (IC50, µg/mL, 24.37) than that of the standard BHT (IC50, µg/mL, 9.67). The reducing power activity of Sa-AgNPs was found as 4.52 (µmol TE/mg extract) while the standard BHT value was 488 (µmol TE/mg extract).


2020 ◽  
Vol 10 (1) ◽  
pp. 1981-1992

The biosynthesis of metallic nanoparticles with plant extract is a promising alternative method to traditional chemical methods. Artemisia annua L is a well-known Chinese herb for its potent therapeutic anti-malarial activity and antitumor effects. Artemisinin, a sesquiterpene lactone derived from Artemisia annua L. Although artemisinin's anticancer effect has been extensively reported, the precise mechanisms underlying its cytotoxicity remain under intensive study. In the present work rapid and simple method for green synthesis of silver nanoparticles with the leaf extract of the therapeutic plant Artemisia annua L.was carried-out. The biologically synthesized silver nanoparticles were analyzed using spectroscopic methods like UV–visible spectroscopy. Fourier transforms infrared spectroscopy (FT-IR), Zeta potential, and particle size. The green Aa-AgNPs are characterized by spectral analysis by Nanodrop-UV-visible spectroscopy. The surface Plasmon resonance peak of silver nanoparticles in colloidal solution showed maximum absorption 441nm. FT-IR spectroscopy results indicate the O-H phenolic group's participation, C=C aromatic stretching, N-H secondary amide stretching, and C-H methylene group stretching. Dynamic light scattering measurements of Aa-AgNPs revealed that the particle size is between 5-20 nm. The zeta potential of the green synthesized Aa-AgNPs was found to be -26.1 mV. The high negative potential indicates long-term stability. The antioxidant activity of Aa-AgNPs was evaluated by DPPH assay. The results revealed that they have very good antioxidant activity, which can be useful as a potential free radical scavenger. The biosynthesized Aa-AgNPs of Artemisia annua exhibited good antimicrobial activity. The Aa-AgNPs showed excellent catalytic activity in the reduction of lemon yellow and orange-red food dyes. The Aa-AgNPs can also act as an effective seed germination agent. Hence it is concluded that the green Aa-AgNPs can be useful for various biomedical and industrial applications.


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