Comparative eco-toxicity of nanoscale TiO2, SiO2, and ZnO water suspensions.
TL;DR: The potential eco-toxicity of nanosized titanium dioxide, silicon dioxide, and zinc oxide water suspensions was investigated using Gram-positive Bacillus subtilis and Gram-negative Escherichia coli as test organisms, with antibacterial activity increasing with particle concentration.
About: This article is published in Water Research.The article was published on 2006-11-01. It has received 1406 citations till now.
Citations
More filters
TL;DR: This review covered ZnO-NPs antibacterial activity including testing methods, impact of UV illumination,ZnO particle properties (size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration.
Abstract: Antibacterial activity of zinc oxide nanoparticles (ZnO-NPs) has received significant interest worldwide particularly by the implementation of nanotechnology to synthesize particles in the nanometer region. Many microorganisms exist in the range from hundreds of nanometers to tens of micrometers. ZnO-NPs exhibit attractive antibacterial properties due to increased specific surface area as the reduced particle size leading to enhanced particle surface reactivity. ZnO is a bio-safe material that possesses photo-oxidizing and photocatalysis impacts on chemical and biological species. This review covered ZnO-NPs antibacterial activity including testing methods, impact of UV illumination, ZnO particle properties (size, concentration, morphology, and defects), particle surface modification, and minimum inhibitory concentration. Particular emphasize was given to bactericidal and bacteriostatic mechanisms with focus on generation of reactive oxygen species (ROS) including hydrogen peroxide (H2O2), OH− (hydroxyl radicals), and O2 −2 (peroxide). ROS has been a major factor for several mechanisms including cell wall damage due to ZnO-localized interaction, enhanced membrane permeability, internalization of NPs due to loss of proton motive force and uptake of toxic dissolved zinc ions. These have led to mitochondria weakness, intracellular outflow, and release in gene expression of oxidative stress which caused eventual cell growth inhibition and cell death. In some cases, enhanced antibacterial activity can be attributed to surface defects on ZnO abrasive surface texture. One functional application of the ZnO antibacterial bioactivity was discussed in food packaging industry where ZnO-NPs are used as an antibacterial agent toward foodborne diseases. Proper incorporation of ZnO-NPs into packaging materials can cause interaction with foodborne pathogens, thereby releasing NPs onto food surface where they come in contact with bad bacteria and cause the bacterial death and/or inhibition.
2,627 citations
Cites background from "Comparative eco-toxicity of nanosca..."
...Distinctive mechanisms that have been put forward in the literature are listed as following: direct contact of ZnO-NPs with cell walls, resulting in destructing bacterial cell integrity [7, 40, 56], liberation of antimicrobial ions mainly Zn ions [57–59], and ROS formation [9, 60–62]....
[...]
...However, ZnO exhibits considerable activity against bacteria under different test conditions [8, 56, 73] and fungi [61]....
[...]
TL;DR: A review of the use of the TiO 2 photocatalyst for remediation and decontamination of wastewater, report the recent work done, important achievements and problems is presented in this paper, however, a lot more is needed from engineering design and modelling for successful application of the laboratory scale techniques to large scale operation.
Abstract: Even though heterogeneous photocatalysis appeared in many forms, photodegradation of organic pollutants has recently been the most widely investigated. By far, titania has played a much larger role in this scenario compared to other semiconductor photocatalysts due to its cost effectiveness, inert nature and photostability. Extensive literature analysis has shown many possibilities of improving the efficiency of photodecomposition over titania by combining the photoprocess with either physical or chemical operations. The resulting combined processes revealed a flexible line of action for wastewater treatment technologies. The choice of treatment method usually depends upon the composition of the wastewater. However, a lot more is needed from engineering design and modelling for successful application of the laboratory scale techniques to large-scale operation. The present review paper seeks to offer an overview of the dramatic trend in the use of the TiO 2 photocatalyst for remediation and decontamination of wastewater, report the recent work done, important achievements and problems.
2,573 citations
TL;DR: This review critiques existing nanomaterial research in freshwater, marine, and soil environments and illustrates the paucity of existing research and demonstrates the need for additional research.
Abstract: The recent advances in nanotechnology and the corresponding increase in the use of nanomaterials in products in every sector of society have resulted in uncertainties regarding environmental impacts. The objectives of this review are to introduce the key aspects pertaining to nanomaterials in the environment and to discuss what is known concerning their fate, behavior, disposition, and toxicity, with a particular focus on those that make up manufactured nanomaterials. This review critiques existing nanomaterial research in freshwater, marine, and soil environments. It illustrates the paucity of existing research and demonstrates the need for additional research. Environmental scientists are encouraged to base this research on existing studies on colloidal behavior and toxicology. The need for standard reference and testing materials as well as methodology for suspension preparation and testing is also discussed.
2,566 citations
TL;DR: The major strategies for designing surfaces that prevent fouling due to proteins, bacteria, and marine organisms are reviewed and ongoing research in this area should result in the development of even better antifouling materials in the future.
Abstract: The major strategies for designing surfaces that prevent fouling due to proteins, bacteria, and marine organisms are reviewed. Biofouling is of great concern in numerous applications ranging from biosensors to biomedical implants and devices, and from food packaging to industrial and marine equipment. The two major approaches to combat surface fouling are based on either preventing biofoulants from attaching or degrading them. One of the key strategies for imparting adhesion resistance involves the functionalization of surfaces with poly(ethylene glycol) (PEG) or oligo(ethylene glycol). Several alternatives to PEG-based coatings have also been designed over the past decade. While protein-resistant coatings may also resist bacterial attachment and subsequent biofilm formation, in order to overcome the fouling-mediated risk of bacterial infection it is highly desirable to design coatings that are bactericidal. Traditional techniques involve the design of coatings that release biocidal agents, including antibiotics, quaternary ammonium salts (QAS), and silver, into the surrounding aqueous environment. However, the emergence of antibiotic- and silver-resistant pathogenic strains has necessitated the development of alternative strategies. Therefore, other techniques based on the use of polycations, enzymes, nanomaterials, and photoactive agents are being investigated. With regard to marine antifouling coatings, restrictions on the use of biocide-releasing coatings have made the generation of nontoxic antifouling surfaces more important. While considerable progress has been made in the design of antifouling coatings, ongoing research in this area should result in the development of even better antifouling materials in the future.
2,278 citations
TL;DR: The antimicrobial mechanisms of several nanoparticles are reviewed, their merits, limitations and applicability for water disinfection and biofouling control are discussed, and research needs to utilize novel nanomaterials for water treatment applications are highlighted.
2,108 citations
Cites background from "Comparative eco-toxicity of nanosca..."
...ZnO nanoparticles exhibit strong antibacterial activities on a broad spectrum of bacteria (Sawai, 2003; Adams et al., 2006; Jones et al., 2008; Huang et al., 2008a)....
[...]
...However, bacterial death also occurred in the dark indicating that other unknown mechanisms may be involved (Adams et al., 2006)....
[...]
References
More filters
Book•
21 May 1993TL;DR: Preface.
Abstract: Preface. Preparation of Media. Media Formulations, Preparation, and Uses. Appendices. Index.
2,774 citations
"Comparative eco-toxicity of nanosca..." refers background in this paper
...MD is a variation of Davis medium in which the potassium phosphate concentration was reduced by 90% ( Atlas, 1993 )....
[...]
...MD is a variation of Davis medium in which the potassium phosphate concentration was reduced by 90% (Atlas, 1993)....
[...]
TL;DR: It is concluded that TiO2 photocatalysis promoted peroxidation of the polyunsaturated phospholipid component of the lipid membrane initially and induced major disorder in the E. coli cell membrane.
Abstract: When titanium dioxide (TiO(2)) is irradiated with near-UV light, this semiconductor exhibits strong bactericidal activity. In this paper, we present the first evidence that the lipid peroxidation reaction is the underlying mechanism of death of Escherichia coli K-12 cells that are irradiated in the presence of the TiO(2) photocatalyst. Using production of malondialdehyde (MDA) as an index to assess cell membrane damage by lipid peroxidation, we observed that there was an exponential increase in the production of MDA, whose concentration reached 1.1 to 2.4 nmol. mg (dry weight) of cells(-1) after 30 min of illumination, and that the kinetics of this process paralleled cell death. Under these conditions, concomitant losses of 77 to 93% of the cell respiratory activity were also detected, as measured by both oxygen uptake and reduction of 2,3,5-triphenyltetrazolium chloride from succinate as the electron donor. The occurrence of lipid peroxidation and the simultaneous losses of both membrane-dependent respiratory activity and cell viability depended strictly on the presence of both light and TiO(2). We concluded that TiO(2) photocatalysis promoted peroxidation of the polyunsaturated phospholipid component of the lipid membrane initially and induced major disorder in the E. coli cell membrane. Subsequently, essential functions that rely on intact cell membrane architecture, such as respiratory activity, were lost, and cell death was inevitable.
1,348 citations
"Comparative eco-toxicity of nanosca..." refers background in this paper
...The greater inhibition in the presence of light supports the notion that the antibacterial activity of TiO2 was related to photocatalytic ROS production ( Maness et al., 1999 )....
[...]
...A concentration of TiO2 ranging from 100 to 1000 ppm has been reported to completely disinfect water containing 105–106 E. coli cells per ml in 30 min under illuminated conditions (Wei et al., 1994; Maness et al., 1999)....
[...]
...The greater inhibition in the presence of light supports the notion that the antibacterial activity of TiO2 was related to photocatalytic ROS production (Maness et al., 1999)....
[...]
...conditions (Wei et al., 1994; Maness et al., 1999 )....
[...]
TL;DR: The results suggest that intratracheal instillation of ultrafine TiO(2) particles may cause an inflammatory response.
966 citations
"Comparative eco-toxicity of nanosca..." refers result in this paper
...Similar results have been reported from mammalian cytotoxicity studies, where TiO2 exerted oxidative stress in the dark under non-photocatalytic conditions ( Gurr et al., 2005 )....
[...]
...Similar results have been reported from mammalian cytotoxicity studies, where TiO2 exerted oxidative stress in the dark under non-photocatalytic conditions (Gurr et al., 2005)....
[...]
TL;DR: Generation of oxidants by crystalline silica particles and by silica-activated cells results in cell and lung injury, activation of cell signaling pathways to include MAPK/ERK kinase (MEK), and extracellular signal-regulated kinases (ERK) phosphorylation, increased expression of inflammatory cytokines, and activation of specific transcription factors.
841 citations
"Comparative eco-toxicity of nanosca..." refers background in this paper
...It is documented that these three compounds are photosensitive and produce reactive oxygen species (ROS) in the presence of light (Yeber et al., 2000; Fubini and Hubbard, 2003; Kubo et al., 2005)....
[...]
...It is documented that these three compounds are photosensitive and produce reactive oxygen species (ROS) in the presence of light (Yeber et al., 2000; Fubini and Hubbard, 2003; Kubo et al., 2005)....
[...]
TL;DR: The antibacterial activity of TiO(2) nanocomposites was investigated qualitatively and quantitatively and the antimicrobial efficiency and inhibition mechanisms are illustrated and discussed.
Abstract: A sol-gel chemistry approach was used to fabricate nanoparticles of TiO(2) in its anatase form. The particle size is shown to be sensitive to the use of HClO(4) or HNO(3) as acid catalyst. The gold-capped TiO(2) nanocomposites were processed by the reduction of gold on the surface of the TiO(2) nanoparticles via a chemical reduction or a photoreduction method. Different percentages of vanadium-doped TiO(2) nanoparticles, which extended the TiO(2) absorption wavelength from the ultraviolet to the visible region, were successfully prepared. The synthesized nanocomposites have a size of about 12-18 nm and an anatase phase as characterized by XRD, TEM, AFM, and UV-vis spectroscopy. The TiO(2) nanocomposite coatings have been applied on glass slide substrates. The antibacterial activity of TiO(2) nanocomposites was investigated qualitatively and quantitatively. Two types of bacteria, Escherichia coli (DH 5alpha) and Bacillus megaterium (QM B1551), were used during the experiments. Good inhibition results were observed and demonstrated visually. The quantitative examination of bacterial activity for E. coli was estimated by the survival ratio as calculated from the number of viable cells, which form colonies on the nutrient agar plates. The antimicrobial efficiency and inhibition mechanisms are illustrated and discussed.
737 citations
"Comparative eco-toxicity of nanosca..." refers background in this paper
...However, other studies have found Gram-positive bacteria to be more sensitive than Gram-negative bacteria to the antibacterial effects of TiO2 (Fu et al., 2005)....
[...]