Wyniki wyszukiwania - BazTech

1

Optimising biosynthesis of antimicrobial copper nanoparticles using aqueous Aegle marmelos leaf extract-based medium

Tarangini Korumilli, Sherlin Shilo Nesa, Jakkala Shanuja, Borah Pallbhika, Wacławek Stanisław, Sabarinath Sankarannair, Rao Korukonda Jagajjanani, Padil Vinod V. T.

Ecological Chemistry and Engineering. S

|

2024

|

Vol. 31, nr 1

7--17

EN

Copper oxide nanostructures have garnered significant attention in nanotechnology for their diverse applications. This study presents a green synthesis approach using an aqueous Aegle marmelos leaf extract-based medium to produce copper oxide (Cu4O3) nanoparticles. Optimisation was achieved through a simplified Taguchi L9 orthogonal array, investigating critical parameters such as temperature, surfactants (AOT and Tween 80), and additives (ascorbic acid and chitosan). Under optimised conditions (AOT: 0.0012 mM, ascorbic acid: 10 mM, chitosan: 1 %, temperature: 80 °C), near-spherical nanoparticles of ~200 nm were obtained. Comprehensive characterisation through UV-Vis, DLS, electron microscopy, XRD, and FTIR spectroscopy confirmed the nanoparticles’ properties, while antibacterial assays showed promising results against Escherichia coli bacteria.

2

Synthesis of silver nanoparticles by aqueous extract of Zingiber officinale and their antibacterial activities against selected species

Hussain Zawar, Jahangeer Muhammad, ur Rahman Shafiq, Ihsan Tamanna, Sarwar Abid, Ullah Najeeb, Aziz Tariq, Alharbi Metab, Alshammari Abdulrahman, Alasmari Abdullah F.

Polish Journal of Chemical Technology

|

2023

|

Vol. 25, nr 3

23--30

EN

Silver nanoparticles have special plasmonic and antibacterial characteristics that make them efficient in a variety of commercial medical applications. According to recent research, chemically synthesized silver nanoparticles are harmful even in low concentrations. It was crucial to identify appropriate synthesis methods that may have low costs and be nontoxic to the environment. Zingiber officinale (ginger) extracts used to prepare silver nanoparticles were inexpensive and environmentally friendly, and the best physicochemical characteristics were analyzed. Silver nanoparticles were characterized by using UV-visible spectroscopy, Scanning electron microscopy (SEM), and X-ray diffraction (XRD). The surface Plasmon resonance peak at 425 nm was observed using UV-Visible spectroscopy. Scanning electron microscopy observed that the nanoparticles were spherical and ranged in size from 5 to 35 nm. The XRD pattern values of 2θ: 38.2° , 46.3° , and 64.58° are used to determine the planes (111), (200), and (220). The silver nanoparticle’s existence was verified by the face-centered cubic (FCC). Silver nanoparticles were found to have antibacterial efficacy against gram-positive Staphylococcus and gram-negative bacteria such as Pseudomonas aeruginosa, Klebsiella Aerogenes, Salmonella, Staphylococcus and Escherichia coli. The antibacterial activity of silver nanoparticles was observed using the agar well diffusion (AWD) method at three different concentrations (100 μg/ ml, 75 μg/ml, and 50 μg/ml). The zone of inhibition measured against the bacterial strains pseudomonas Aeruginosa, Klebsiella aerogenes, Escherichia coli, Salmonella and Staphylococcus which were (18.4±1.25 mm, 16.9±0.74 mm, 14.8±1.25 mm), (16.8±0.96 mm, 14.6±0.76 mm, 14.0±1.15 mm), (19.7±0.76 mm, 18.2±0.66 mm, 15.4±1.15 mm), (16.6±0.67 mm, 14.2±0.23 mm, 12.8±0.78 mm) and (12±0.68 mm, 10±0.20 mm, 08±0.15 mm). These nanoparticles’ potent antibacterial properties may enable them to be employed as nanomedicines for a variety of gramnegative bacterial illness treatments.

3

Eco-friendly high-rate formation of silver nanoparticles in agave inulin and its bactericidal effect against Escherichia coli

Sánchez-Vieyra María Teresa, Ojeda-Martínez Miguel, Oceguera-Contreras Eden, Rodríguez-Preciado Sergio Yair, Díaz-Zaragoza Mariana, Martínez-Zérega Brenda Esmeralda, González-Solís José Luis, Oseguera-Galindo David Omar

Materials Science Poland

|

2023

|

Vol. 41, No. 3

62--73

EN

A high rate of silver nanoparticle formation, effective against the Escherichia coli (E. coli) bacterium, was obtained for the first time by means of a simple, eco-friendly, and low-cost green method in a solution of agave inulin. The study was carried out using the traditional method, in which the effects of the concentration of agave inulin, AgNO3, temperature, and pH on the synthesis were analyzed by UV-Vis spectroscopy and transmission electron microscopy (TEM). Most of the nanoparticles produced were spherical with a size less than 10 nm. In a sample with 20 mg/mL of agave inulin, 1 mM of AgNO3, T = 23°C, and pH = 12, the highest percentage of Ag+ ions available in the solution were reduced for the formation of nanoparticles in less than 40 min, whereas a sample prepared with 60 mg/mL of agave inulin, 10 mM of AgNO3, T = 23°C, pH = 12, and a storage time of 40 min showed a significant bactericidal effect on the E. coli strain. Agave inulin is a good biological compound for the formation of small, spherical silver nanoparticles. A pH of 12 favors a higher production speed of the silver nanoparticles and better use of the available Ag+ ions. In addition to this, the concentration of AgNO3 is a determining factor for increased formation of the nanoparticles necessary to bactericidal effect.

4

Facile green synthesis of Cinnamomum tamala extract capped silver nanoparticles and its biological applications

Narath Sajina, Shankar S. Sharath, Sivan Saranya Kothaplamoottil, George Bini, Thomas T. Dennis, Sabarinath Sankarannair, Jayaprakash Sajithkumar K., Wacławek Stanisław, Padil Vinod V. T.

Ecological Chemistry and Engineering. S

|

2023

|

Vol. 30, nr 1

7--21

EN

The plant mediated biogenic synthesis of nanoparticles is of magnificent concern due to its eco-benign and single pot nature. Here, Cinnamomum tamala (C. tamala) aqueous leaf extract was utilised for the silver nanoparticles’ (Ag NPs) synthesis. The phytoconstituents in the leaf extract were analysed by standard methods. These metabolites, especially carbohydrate polymers reduce Ag ions to Ag NPs accompanied by a reddish-brown coloration of the reaction mixture. The visual observation of intense brown colour is the first indication of the formation of Ag NPs. Various spectro-analytical techniques further characterise the Ag NPs. The green synthesised spherical Ag NPs were crystalline with an average size of 38 nm. The Ag NPs were scrutinised for antioxidant, antimicrobial and cytotoxic activity and obtained good results. The free radical scavenging was studied by 2, 2-Diphenyl-l-picrylhydrazyl (DPPH) assay. The antibacterial activity of Ag NPs was assessed against human pathogens, and it shown to have good antibacterial potency against a wide spectrum of bacteria. The cytotoxic activity against HEK-293T (human embryonic kidney) cell line was evaluated by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay. These potent biological activities enable C. tamala capped Ag NPs to be suitable candidates for the future applications in various fields, predominantly clinical and biomedical.

5

Biosynthetic of Titanium Dioxide Nanoparticles Using Zizyphus Spina-Christi Leaves Extract: Properties

Alobaidi Tuqa B., Alwared Abeer I.

Journal of Ecological Engineering

|

2022

|

Vol. 23, nr 1

315--324

EN

The present project utilizes a straightforward, inexpensive, and environmentally friendly approach to produce Titanium dioxide nanoparticles utilizing Zizyphus Spina-Christi leaves (Z-TiO2). Ultra-Spectrophotometry (UV-Vis) was used to characterize the synthesized nanoparticles, which showed the production of nanoparticles at 320 nm absorbance. To investigate functional groups, Fourier Transform Infrared Spectroscopy (FTIR) has been used. The presence of Titanium Dioxide was verified using Energy Distribution X-ray Spectroscopy (EDS). Surface area is calculated using the Brunauer Emmett Teller (BET) formula. Images from Field Emission Electron Microscopy (FE-SEM) verified the nanoparticles' spherical shape and relatively homogenous size distribution. These findings demonstrated that the production of Z-TiO2 nanoparticles was successful.

6

Bioeffects of silver nanoparticles (AgNPs) synthesized by producer of biosurfactant Bacillus subtilis strain : in vitro cytotoxicity, antioxidant properties and metabolic activities of mammalian cells

Chojniak-Gronek Joanna Małgorzata, Jałowiecki Łukasz, Płaza Grażyna Anna

Archives of Environmental Protection

|

2022

|

Vol. 48, no. 4

45--52

EN

The present study is focused on the evaluation of bioeffects of silver nanoparticles (AgNPs) synthesized by Bacillus subtilis strain I’-1a, the producer of iturin A lipopeptide biosurfactant. The following properties of biologically synthesized silver nanoparticles (bio-AgNPs) were evaluated: in vitro cytotoxicity, antioxidant properties, and metabolic activities of mammalian cells. As a control, chemically synthesized silver nanoparticles (chem-AgNPs) were used. In vitro, antioxidant activity of bio-AgNPs showed a significant effect on the scavenging of free radicals. Bio-AgNPs can be potent natural antioxidants and can be essential for health preservation against oxidative stress-related degenerative diseases, such as cancer. The cell viability of human skin fibroblasts NHDF was remarkably inhibited in the presence of both AgNPs. However, bio-AgNPs were more active than chem-AgNPs. In our experiment, microarrays PM-M1–PM-M4 were used to evaluate the growth of NHDF fibroblast cells in the presence of bio-AgNPs and chem-AgNPs. The NHDF fibroblast cells were more active in the presence of bio-AgNPs than in chem-AgNPs. Probably, the presence of biosurfactant produced by Bacillus subtilis I’-1a significantly increased the stability of biogenic AgNPs and enhanced their biological activities and specific interaction with human DNA. Furthermore, the evaluated biological activities were enhanced for the biosurfactant-based AgNPs.

7

Synteza nanocząstek srebra przy użyciu ekstraktów roślinnych

Knurek Jakub, Buchaj Aleksandra, Garbacz Monika

Inżynieria i Ochrona Środowiska

|

2019

|

T. 22, nr 1

63--74

EN

The field of nanotechnology is the most dynamic region of research in material sciences and the synthesis of nanoparticles is picking up significantly throughout the world. This trend is related to the possibilities of using them in many disciplines, including microbiology, biotechnology and laboratory diagnostics. Due to the high interest in nanoparticles synthesis, the methods of formation and stabilization of nanometric particles have become the subject of many studies in recent years. Medicinally active plants have proven to be the best reservoirs of diverse phytochemicals for the synthesis of biogenic silver nanoparticles. The resulting structures are characterized by optimal properties, and the method used is more ecological than chemical reduction. Accordingly, this review presents different methods of preparation silver nanoparticles and application of these nanoparticles in different fields.

PL

Nanotechnologia jest jedną z najbardziej dynamicznych dyscyplin badań w dziedzinie inżynierii materiałowej, a liczba syntez nanocząstek metali znacząco rośnie na całym świecie. Ten trend związany jest z możliwościami wykorzystania ich w wielu dyscyplinach nauki, m.in. mikrobiologii, biotechnologii i diagnostyce laboratoryjnej. Ze względu na duże zainteresowanie nanocząstkami metody tworzenia i stabilizacji nanometrycznych cząstek stały się w ostatnich latach przedmiotem wielu badań. Udowodniono, że ekstrakty roślinne, zawierające zespół związków fitochemicznych, mogą być wykorzystywane do syntezy biogennych nanocząstek srebra. Powstałe struktury charakteryzują się stosownymi właściwościami, a metoda „zielonej” syntezy jest bardziej ekologiczna od innych technik. W związku z tym w artykule przedstawiono różne metody biosyntezy nanocząstek srebra oraz ich interdyscyplinarne zastosowania.

8

Green synthesis, characterization and biological activities of silver nanoparticles using the bark extract of ailanthus altissima

Arshad M., Khan A., Farooqi Z. H., Usman M., Waseem M. A., Shah S. A., Khan M.

Materials Science Poland

|

2018

|

Vol. 36, No. 1

21--26

EN

Due to their potential application in various fields of science and technology, the eco-friendly bio-synthesis of silver (Ag) nanoparticles (NPs) is a growing area for researchers. In this study, we report the green synthesis of Ag nanoparticles and their characterization by using various techniques. For the preparation of Ag particles, aqueous plant extract of ailanthus altissima was used as a reducing medium for Ag+ ions of silver nitrate to Ag0. UV-Vis spectrophotometry was used to trace the formation of Ag particles by noting their surface plasmon resonance peaks (400 nm to 440 nm). Fourier transform infrared spectroscopy (FT-IR) was employed to reveal the chemical composition of Ag nanoparticles which were capped by plant extract. Scanning electron microscopy (SEM) was used to get the lattice image, morphology and average size of Ag particles. The average size distribution of Ag NPs dispersed in aqueous media was also measured using dynamic light scattering (DLS). It was found that DLS results are in good agreement with those obtained from SEM. The synthesized particles were then subjected to the antibacterial and antifungal activities by studying them against various species, such as bacillus cereus, staphylococcus aureus, pseudomonas aeruginosa, E. coli and A. parasiticus, A. niger and A. flavus fungi. It was noted from the growth curves of both bacteria and fungi that in the presence of silver nanoparticles they show more in-zone growth as compared to the plant extract.

9

Microwave assisted biosynthesis of rice shaped ZnO nanoparticles using Amorphophallus konjac tuber extract and its application in dye sensitized solar cells

Kumar P. N., Sakthivel K., Balasubramanian V.

Materials Science Poland

|

2017

|

Vol. 35, No. 1

111--119

EN

Rice shaped ZnO nanoparticles have been synthesized for the first time by a biological process using Amorphophallus konjac tuber extract and used as a photoanode in a dye sensitized solar cell. The glucomannan present in aqueous tuber extract acted as a reducing agent in the synthesis process, further it also acted as a template which modified and controlled the shape of the nanoparticles. The synthesized nanoparticles were dried by microwave irradiation followed by annealing at 400 °C. The FESEM and TEM images confirmed that the synthesized ZnO nanoparticles had rice shaped morphology. Furthermore, the X-ray diffraction studies revealed that the prepared ZnO nanoparticles exhibited wurtzite phase with average particle size of 17.9 nm. The UV-Vis spectroscopy studies confirmed the value of band gap energy of biosynthesized ZnO nanoparticles as 3.11 eV. The photoelectrodes for dye sensitized solar cells were prepared with the biosynthesized ZnO nanoparticles using doctor blade method. The photoelectrode was sensitized using the fruit extract of Terminalia catappa, flower extracts of Callistemon citrinus and leaf extracts of Euphorbia pulcherrima. The dye sensitized solar cells were fabricated using the sensitized photoelectrode and their open circuit voltages and short circuit current densities were found to be in the range of 0.45 V to 0.55 V and 5.6 mA/cm2 to 6.8 mA/cm2, respectively. Thus, the photovoltaic performances of all the natural dye sensitized ZnO solar cells show better conversion efficiencies due to the morphology and preparation technique.

10

Chitosan-based nanocomposites modified with reduced graphene oxide prepared via green synthesis

Kosowska K., Domalik-Pyzik P., Jagiełło J., Lipińska L., Chłopek J.

Engineering of Biomaterials

|

2017

|

Vol. 20, no. 143 spec. iss.

59

11

Green synthesis of silver nanoparticles using tannins

Raja P B, Rahim A A, Qureshi A K, Awang K

Materials Science Poland

|

2014

|

Vol. 32, No. 3

408--413

EN

Colloidal silver nanoparticles were prepared by rapid green synthesis using different tannin sources as reducing agent viz. chestnut (CN), mangrove (MG) and quebracho (QB). The aqueous silver ions when exposed to CN, MG and QB tannins were reduced which resulted in formation of silver nanoparticles. The resultant silver nanoparticles were characterized using UV-Visible, X-ray diffraction (XRD), scanning electron microscopy (SEM/EDX), and transmission electron microscopy (TEM) techniques. Furthermore, the possible mechanism of nanoparticles synthesis was also derived using FT-IR analysis. Spectroscopy analysis revealed that the synthesized nanoparticles were within 30 to 75 nm in size, while XRD results showed that nanoparticles formed were crystalline with face centered cubic geometry.

12

Green synthesis and characterization of cuprous oxide nanoparticles in presence of a bio-surfactant

Behera M, Giri G

Materials Science Poland

|

2014

|

Vol. 32, No. 4

702--708

EN

Herein, we report a facile green synthesis of Cu2O nanoparticles (NPs) using copper sulfate as precursor salt and hydrazine hydrate as reducing agent in presence of bio-surfactant (i.e. leaves extract of arka – a perennial shrub) at 60 to 70 °C in an aqueous medium. A broad band centered at 460 nm in absorption spectrum reveals the formation of surfactant stabilized Cu2O NPs. X-ray diffraction pattern of the surfactant stabilized NPs suggests the formation of only Cu2O phase in assistance of a bio-surfactant with the crystallite size of ∼8 nm. A negative zeta potential of −12 mV at 8.0 pH in surfactant stabilized Cu2O NPs hints non-bonding electron transfer from O-atom of saponin to the surface of NP. Red-shift in the vibrational band (Cu–O stretching) of Cu2O from 637 cm−1to 640 cm−1 in presence of bio-surfactant suggests an interfacial interaction between NPs and O-atoms of –OH groups of saponin present in the plant (i.e. Calotropis gigantea) extract. From X-ray photoelectron spectroscopy spectra, a decrease in binding energy of both 2p3/2and 2p1/2 bands in Cu2O with saponin molecules as compared to bulk Cu atom reveals a charge transfer interaction between NP and saponin surfactant molecules. Transmission electron microscopy images show crystalline nature of Cu2O NPs with an fcc lattice.

13

PEG mediated eco-friendly one pot sunthesis of benzylamine coumarin derivatives using multicomponent reactant

Viradiya D. J., Kotadiya V. C, Khunt M. D., Baria B. H., Bhoya U. C.

International Letters of Chemistry, Physics and Astronomy

|

2014

|

Vol. 11, iss. 2

177-184

EN

A green resourceful, eco-friendly and facile protocol was developed for the synthesis of benzylamine coumarin derivatives by the reaction of 4-hydroxy coumarin, secondary amine and aromatic aldehyde in the presence of PEG400 as a solvent as well as catalyst at room temperature. A wide range of functional groups were tolerated in the developed protocol. The structures of all the synthesized compounds were confirmed by 1H NMR, IR, MASS and Elemental Analysis. The target molecules were obtained in good to excellent yield applying this method.

14

Bio synthesis and characterization of silver nanoparticles using Lagenaria siceraria leaf extract and their antibacterial activity

Anandh B., Muthuvel A., Emayavaramban M.

International Letters of Chemistry, Physics and Astronomy

|

2014

|

Vol. 19, iss. 1

35--45

EN

The present investigation demonstrates the formation of silver nanoparticles by the reduction of the aqueous silver metal ions during exposure to the Lagenaria siceraria leaf extract. The synthesized AgNPs have characterized by UV-visible spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) techniques. AgNPs formation has screened by UV-visible spectroscopy through colour conversion due to surface plasma resonance band at 427 nm. X-ray diffraction (XRD) confirmed that the resulting AgNPs are highly crystalline and the structure is face centered cubic (fcc). FT-IR spectrum indicates the presence of different functional groups present in the biomolecules capping the nanoparticles. Further, inhibitory activity of AgNPs and leaf extract were tested against human pathogens like gram-pastive (Staphylococcus aureus, Bacillus subtilis), gram-negative (Escherichia coli and Pseudomonas aeruginosa). The results indicated that the AgNPs showed moderate inhibitory actions against human pathogens than Lagenaria siceraria leaf extract, demonstrating its antimicrobial value against pathogenic diseases.

15

Pro-ecological methods for synthesis of nickel nanoparticles for composite applications

Marzec A., Pędzich Z.

Composites Theory and Practice

|

2014

|

R. 14, nr 2

76--80

EN

Composites containing nickel nanoparticles dispersed in a ceramic polycrystalline matrix are widely utilized materials for different applications. They are utilized in ceramic matrix/metallic additive composites due to their profitable influence on both the mechanical (grain size growth control, stress relaxation on crack tip by plastic deformation) and functional properties. A zirconia/nano-Ni composite is an important material for solid oxide fuel cell electrodes possessing unique electrochemical properties. Another composite composed of alumina and nano-Ni is a widely investigated structural material showing excellent mechanical properties. The paper presents an innovative pro-ecological method for synthesizing nickel nanoparticles to be used in ceramic matrix/metal particle composites, which could be used as an alternative to traditional methods. The proposed biochemical syntheses minimise or even completely eliminate the amount of produced waste and could be implemented as sustainable processes accepting the basic principles of “green chemistry”. The suggested method enables precise size control of the created nanoparticles and at the same time offers numerous advantages in comparison to conventional methods.

PL

Nanocząstki niklu znajdują zastosowanie w wielu dziedzinach. Wykorzystuje się je m.in. w kompozytach ceramiczno-metalicznych, gdzie wpływają pozytywnie nie tylko na mechaniczne właściwości kompozytu (kontrola rozrostu ziaren, relaksacja naprężeń przy wierzchołku pęknięcia na skutek kontaktu z fazą plastyczną), ale również na jego właściwości funkcjonalne. Kompozyty zawierające nanocząstki niklu rozproszone w osnowie polikrystalicznego tlenku cyrkonu są wykorzystywane m.in. do budowy elektrod w ogniwach paliwowych z zestalonym elektrolitem tlenkowym (SOFC). Innym przykładem kompozytu zawierającego nanocząstki niklu jest materiał wykazujący znakomite właściwości mechaniczne zbudowany z nanocząstek niklu i Al2O3. W artykule przedstawiono proekologiczną, innowacyjną metodę syntezy nanocząstek niklu do zastosowania w kompozytach ceramiczno-metalicznych jako alternatywę dla metod tradycyjnych. Zaproponowana metoda pozwala nie tylko na precyzyjną kontrolę wielkości powstających nanocząstek, ale również ich równomierne rozłożenie w matrycy ceramicznej, realizując przy tym zasady „zielonej chemii”.

16

Metal nanoparticles and plants

Masarovičová E., Kráľová K.

Ecological Chemistry and Engineering. S

|

2013

|

Vol. 20, nr 1

9-22

EN

Metal nanoparticles (MNPs) belong mostly to the engineered type of nanoparticles and have not only unique physical and chemical properties but also different biological actions. In recent years, noble MNPs and their nano-sized agglomerates (collectively referred to as nanoparticles or particles in the subsequent sections) have been the subjects of much focused research due to their unique electronic, optical, mechanical, magnetic and chemical properties that can be significantly different from those of bulk materials. To enhance their use, it is important to understand the generation, transport, deposition, and interaction of such particles. Synthesis of MNPs is based on chemical or physical synthetic procedures and by use of biological material ("green synthesis" as an environmentally benign process) including bacteria, algae and vascular plants (mainly metallophytes). In biological methods for preparation of metal nanoparticles mainly leaf reductants occurring in leaf extracts are used. MNPs can be formed also directly in living plants by reduction of the metal ions absorbed as a soluble salt, indicating that plants are a suitable vehicle for production of MNPs. These methods used for preparation of MNPs are aimed to control their size and shape. Moreover, physicochemical properties of MNPs determine their interaction with living organisms. In general, inside the cells nanoparticles might directly provoke either alterations of membranes and other cell structures or activity of protective mechanisms. Indirect effects of MNPs depend on their physical and chemical properties and may include physical restraints, solubilization of toxic nanoparticle compounds or production of reactive oxygen species. Toxic impacts of MNPs on plants is connected with chemical toxicity based on their chemical composition (eg release of toxic metal ions) and with stress or stimuli caused by the surface, size and shape of these nanoparticles. Positive effects of MNPs were observed on the following plant features: seed germination, growth of plant seedlings, stimulation of oxygen evolution rate in chloroplasts, protection of chloroplasts from aging for long-time illumination, increase of the electron transfer and photophosphorylation, biomass accumulation, activity of Rubisco, increase of quantum yield of photosystem II, root elongation, increase of chlorophyll as well as nucleic acid level and increase in the shoot/root ratio. However, it should be stressed that MNPs impact on human and environmental health remains still unclear.

PL

Ze względu na unikalne właściwości fizyczne i chemiczne, ale także różne działanie biologiczne nanocząstek metali (MNPS) są obiektem zainteresowania nowo powstałej inżynierii tych materiałów. W ostatnich latach MNPS metali szlachetnych (zbiorowo określane w dalszej części tekstu jako nanocząstki lub cząstki) były poddawane wielu badaniom ze względu na ich unikalne właściwości elektroniczne, optyczne, mechaniczne, magnetyczne i chemiczne, które mogą być znacząco różne od właściwości materiałów litych. Synteza MNPS polega na procesach chemicznych lub fizycznych oraz na wykorzystaniu materiału biologicznego ("zielona synteza" - proces przyjazny środowisku), w tym bakterii, glonów i roślin naczyniowych (głównie metalofitów). W biologicznych metodach wytwarzania nanocząstek metali używane są głównie substancje redukujące, występujące w ekstraktach z liści. MNPS również mogą być utworzone bezpośrednio w żywych roślinach przez redukcję jonów metali absorbowanych w postaci rozpuszczalnych soli, co wskazuje, że rośliny są odpowiednim środkiem produkcji MNPS. Metody te pozwalają na kontrolę rozmiarów i kształtu cząstek. Jest to ważne, ponieważ właściwości fizykochemiczne MNPS określają ich oddziaływanie z żywymi organizmami. Zwykle w komórkach nanocząstki mogą bezpośrednio wywoływać zmiany w błonach komórkowych albo w innych strukturach oraz mogą wpływać na aktywność komórek lub na ich mechanizmy ochronne. Pośrednio skutki działania MNPS zależą od ich właściwości fizycznych i chemicznych. Skutki te mogą obejmować ograniczenia fizyczne, rozpuszczanie toksycznych MNPS lub wytwarzanie reaktywnych form tlenu. Toksyczny wpływ MNPS na rośliny jest związany z toksycznością chemiczną, uzależnioną od składu chemicznego (np. uwalnianie toksycznych jonów metali) oraz ze stymulacją lub napięciami wywołanymi przez kontakt z powierzchnią. Istotne są także rozmiary i kształt nanocząstek. Pozytywne wpływy MNPS obserwowano na: kiełkowanie nasion, wzrost siewek roślin, stymulację tempa przemiany tlenu w chloroplastach, ochronę przed starzeniem chloroplastów wywołanym przez długotrwałe oświetlanie, zwiększenie transferu elektronów i fotofosforylacji, gromadzenie biomasy, aktywność RuBisCO, wzrost wydajności kwantowej fotosystemu II, wzrost korzeni, wzrost chlorofilu, jak również poziomu kwasów nukleinowych i stosunku długości pędów i korzeni. Jednak należy podkreślić, że wpływ MNPS na zdrowie ludzi i na środowisko jest nadal niejasny.

17

Occurrence, characterization and action of metal nanoparticles

Masarovičová E., Kráľová K.

Proceedings of ECOpole

|

2012

|

Vol. 6, No. 2

445--449

EN

Metal nanoparticles (MNPs) are attracting attention for many technological applications as catalysts, in optical materials, medical treatments, sensors, and in energy storage and transmission. The function and use of these materials depend on their composition and structure. A practical route for synthesis of MNPs is by chemical procedure and by use of biological material (“green synthesis” as a dependable, environmentally benign process) including bacteria, algae and vascular plants (mainly metallophytes). Currently, there are various chemical and physical synthetic methods used for preparation of metal nanoparticles and several experimental techniques aimed at controlling the size and shape of MNPs. Toxic effects of MNPs on plants could be connected with chemical toxicity based on their chemical composition (eg release of toxic metal ions) and with stress or stimuli caused by the surface, size and shape of the particle. The physicochemical properties of nanoparticles determine their interaction with living organisms. In general, plant cells possess cell walls that constitute a primary site for interaction and a barrier for the entrance of nanoparticles. Inside cells, nanoparticles might directly provoke either alterations of membranes and other cell structures or activity of protective mechanisms. Indirect effects of MNP depend on their chemical and physical properties and may include physical restraints, solubilization of toxic nanoparticle compounds, or production of reactive oxygen species. However, it should be stressed that impact of MNPs on human and environmental health remains still unclear. Thus, evaluation scheme for national nanotechnology policies (that would be used to review the whole national nanotechnology plan) was recommended. The three following criteria for policy evaluation were suggested: appropriateness, efficiency and effectiveness.

PL

Nanocząstki metali (MNPS) przyciągają uwagę ze względu na ich wykorzystanie w wielu zastosowaniach jako katalizatory, materiały optyczne, czujniki, w zabiegach medycznych, w przechowywaniu i transmisji energii. Funkcja i zastosowanie tych materiałów zależą od ich składu i struktury. Praktycznymi drogami syntezy MNPS są metody chemiczne i wykorzystanie materiałów biologicznych („zielona synteza” niezawodna, przyjazna środowisku), w tym bakterii, glonów i roślin naczyniowych (głównie metalofitów). Obecnie stosowane są różne fizyczne i chemiczne metody wytwarzania nanocząstek metali i kilka technik eksperymentalnych, mających na celu kontrolę wielkości i kształtu MNPS. Toksyczny wpływ MNPS na rośliny może być związany z toksycznością chemiczną ze względu na ich skład chemiczny (np. uwalnianie jonów metali) oraz stresem lub stymulacją spowodowanymi przez powierzchnię, wielkość i kształt cząstek. Interakcje z organizmami żywymi są określane przez fizykochemiczne właściwości nanocząstek. Ogólnie rzecz biorąc, ściany komórkowe roślin stanowią podstawowy element interakcji i barierę wejścia nanocząstek. Wewnątrz komórek nanocząstki mogą bezpośrednio wywoływać zarówno zmiany błon komórkowych, jak i innych struktur lub spowodować aktywizację mechanizmów ochronnych. Pośrednie skutki MNP zależą od ich właściwości chemicznych i fizycznych, mogących prowadzić do tworzenia pewnych ograniczeń fizycznych, rozpuszczania związków toksycznych czy wytwarzania reaktywnych form tlenu. Jednak należy podkreślić, że wpływ MNPS na zdrowie ludzi i stan środowiska jest nadal niejasny. Z tego względu konieczne jest stworzenie schematu systemu oceny polityki w dziedzinie nanotechnologii (które zostaną wykorzystane do przeglądu całości krajowego planu nanotechnologicznego). Zaproponowano trzy następujące kryteria oceny polityki: adekwatność, efektywność i skuteczność.