Suspensions Of ZnO Nanoparticles Research Articles

The Optimal Parameter for Coating ZnO Nanoparticle on Orthodontic Molar Tube by Electrophoretic Deposition Method (An Invitro Study)

The fixed orthodontic appliance may enhance devious pathogens and increase biofilm accumulation around the orthodontic molar tube (OMT) surface, which may cause demineralization of the tooth surface. However, the stainless-steel OMT coated with ZnO nanoparticles may enhance antimicrobial efficacy and reduce biofilm accretion. The study aimed to identify the optimal parameter for coating orthodontic molar tubes with antimicrobial ZnO nanoparticles by the electrophoretic deposition (EPD)cell. 36 orthodontic molar tubes were included in this study. The coating process was carried out using an EPD cell. Various concentrations (7.5, 10, 20, 33) g/L of ZnO nanoparticles suspension were conducted in this study, in addition to multiple times and voltages. After the coating process, the samples were left to dry for 24 hours at room temperature. To confirm the coating and adhesion a qualitative tape test and the Scanning Electron microscope were used to study the morphological, topographical, and surface characteristics and the size of nanoparticles on the surface of the coated OMT. The innovative ZnO nanoparticles exhibit promising antibacterial properties against oral pathogens, leading to a decrease in plaque buildup, which may decrease tooth cavities and gingival irritation through orthodontic treatment. There was an increase in nanoparticle surface adhesion on the orthodontic molar tube surface at 2 mins deposition time while reduced surface adhesion as increased deposing time. The coating process was verified at a currency voltage of 30V, reducing nanoparticle agglomeration. A concentration of 10g/L of ZnO suspension shows the most stable and homogenous suspension.

Tuning the efficiency of Random Laser Generation in a Suspension of ZnO Nanoparticles by Means of its Directional Freezing

Tuning the efficiency of Random Laser Generation in a Suspension of ZnO Nanoparticles by Means of its Directional Freezing

Antimicrobial effect of hydro-alcoholic extract of apple with and without zinc oxide nanoparticles on Streptococcus Mutans.

This study aimed to evaluate the antimicrobial effect of hydro-alcoholic extract of apple (Malus domestica Borkh. Vs.golab, with and without ZnO nanoparticles) on Streptococcus Mutans bacterium compared to 0.2% Chlorhexidine, Persica and suspension of ZnO nanoparticles. Study samples were examined in the groups of apple hydro-alcoholic extract with and without addition of ZnO nanoparticles, a positive control group (Chlorhexidine 0.2%, Persica and suspension of ZnO nanoparticles), and a negative control group (distilled water). In this experiment, a concentration of 500 PPM of ZnO nanoparticles with a diameter of 0.4 nm was used. Agar diffusion method was used to determine the Minimum Inhibitory Concentration (MIC) of apple hydro-alcoholic extract with and without adding ZnO nanoparticles. The concentrations used were 200, 100, 50 and 25 mg/ml. ANOVA statistical test was used to compare the average in the study groups. According to our results, hydro-alcoholic extract of apples alone had no effect on the target bacteria in any of the concentrations. In the group of apple hydro-alcoholic extract with ZnO nanoparticles, the mean inhibition zone was 13 mm at a concentration of 25 mg/ml. 0.2% Chlorhexidine, Persica and suspension of ZnO nanoparticles was observed with the mean inhibition zone of 20 mm, 16 mm and 15 mm, respectively. Hydro-alcoholic extract of apple with addition of ZnO nanoparticles in concentration of 25mg/ml, had growth inhibitory effect on Streptococcus Mutans, but it was not remarkably efficient in comparison with Chlorhexidine.

Learning in colloids: Synapse-like ZnO + DMSO colloid

Colloids subjected to electrical stimuli exhibit a reconfiguration that might be used to store information and potentially compute. In a colloidal suspension of ZnO nanoparticles in DMSO, we investigated the learning, memorization, time and stimulation’s voltage dependence of conductive network formation. The relationships between the critical resistance and stimulation time have been reconstructed. The critical voltage (i.e., the stimulation voltage required to drop the resistance) was found to decrease as stimulation time increased. We characterized a dispersion of conductive ZnO nanoparticles in the DMSO polymeric matrix using FESEM and UV–visible absorption spectrum.

Eco-friendly approach for ZnO nanoparticles synthesis and evaluation of its possible antimicrobial, larvicidal and photocatalytic applications

The synthesis of nanoparticles (NPs) from plants is a viable eco-friendly approach with applications in different sectors. Thus, we aim to synthesize and characterize zinc oxide NPs (ZnO NPs) from Ficus racemosa L. leaf extract and to evaluate their larvicidal potential against Aedes albopictus larvae, their efficacy against human clinical pathogenic bacteria (Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli). Furthermore, we evaluated its use in photocatalytic rhodamine B (RhB) dye degradation and its possible acute toxicity to a non-target organism (Artemia salina). The biosynthesized ZnO NPs were characterized using UV–Vis, XRD, SEM-EDX, TEM, and FT-IR. UV–vis absorption spectrum indicates that the green synthesized ZnO NPs absorb at the wavelength centered at 365 nm, corresponding to the band gap of 3.2 eV. We reported that A. albopictus mosquito larvae were highly susceptible to ZnO NPs, especially when exposed to 250 μg ZnO NPs/mL. The reduction of acetylcholinesterase (AChE) activity and the carboxylesterases phosphatases evaluated was concentration-dependent, constituting a possible mechanism of larvicidal action of NPs. Biosynthesized ZnO NPs also significantly inhibited the growth of the bacterial species evaluated, suggesting good bactericidal activity. Furthermore, the ZnO NPs efficiently degraded RhB dye in an aqueous solution under UV light irradiation, proving promising in dye remediation in wastewater. Finally, ZnO NPs suspension exhibited lower acute toxicity of A. salina after 48 h of exposure. Therefore, our study pioneeringly demonstrates that biosynthesis of ZnO NPs from F. racemosa leaf extract can be a great approach to developing versatile and environmental products.

H2 production from the radiolysis of aqueous suspensions of ZnO nanoparticles by 5.5 MeV He2+ ions

The effects of ion beam irradiation on aqueous suspensions of metal oxides has received relatively little attention compared to γ-ray irradiation despite being a highly prevalent process in spent nuclear fuel storage and reprocessing. This is partly due to the difficulties associated with homogeneously irradiating condensed-phase matter using α-particles. Here, we report experimental yields of H2 from the 5.5 MeV He2+ ion irradiation of aqueous suspensions of ZnO nanoparticles. The obtained results are compared to our previously measured results for the γ-radiolysis of the same system. The amount of H2 increases linearly with adsorbed dose for all studied concentrations. The measured yields are of the same order of magnitude as those observed for pure water, but decrease with increasing water content. Overall, the yields follow a similar trend to those observed for γ-ray radiolysis.

Microliter-stirred sample setup for X-ray spectroscopy analysis of nanomaterials in suspension

Analysis of samples in the liquid environment using X-ray spectroscopy techniques is a very attractive approach as it provides specimen characterization in its native conditions thanks to the penetrating properties of X-rays. However, very often due to challenging synthesis procedures and the high cost of specimens it is difficult to obtain a sample in quantities for optimal measurement. Additionally, nanoparticles (NPs) aqueous suspensions are often not stable and undergo agglomeration and sedimentation processes that can be avoided either by sonication or sample stirring. Relatively small sample volumes and intrinsic agglomeration processes make X-ray spectroscopy measurements challenging especially when long periods are needed for the collection of high-quality data. To address both issues, we developed dedicated sample system that allows measurements down to few tens of μL of the liquid sample with capability of continuous stirring of the suspension. The X-ray spectroscopy measurements of ZnO nanoparticles suspension in water showed a stable signal for hours of acquisition time. On the other hand, in the absence of stirring, agglomeration and subsequent sedimentation processes were visible already within few minutes with maximum sedimentation rate of 2.5% of concentration loss in the beam field per minute.

Comparison of oxidative treatments of polypropylene films and fibers to promote zinc oxide nanoparticle adhesion

Ozone, heating-in-air, and chromic acid treatments of polypropylene (PP) films and fibers were evaluated for their ability to promote ZnO nanoparticle (NP) adhesion. X-ray photoelectron spectroscopy (XPS) demonstrated that the oxygen content of the surface of PP films increased due to all treatments, with high binding energy O1s components emerging consistent with carbonyl, carboxylic acid, ester and hydroperoxide groups. The latter two were dominant for chromic acid treatment. The XPS measurements were complemented by attenuated total reflectance FTIR spectroscopy studies. Pull-off measurements from PP films, using a ZnO particle attached to the cantilever of an atomic force microscope, indicated that ozone and chromic acid treatments were equally effective at increasing adhesive forces. However, scanning electron microscopy studies of PP fibers treated with either ozone or chromic acid, and subsequent immersion in an ethanolic ZnO NP suspension, showed that ozone treatment was more effective than chromic acid treatment at promoting adhesion. This likely results from the poorer ability of ester and hydroperoxide groups, compared to carboxylic acid ones, to bind to hydroxylated ZnO NPs. It was further shown that excessive ozone treatment leads to brittleness of the fibers, as evidenced by cracking when the fibers are stirred. These results indicate that moderate ozone treatment of PP films and fibers may be a convenient method to attach metal oxide particles to PP surfaces.

Intermolecular Interactions Studies of ZnO-Tryptophan Suspension

The physicochemical properties (PCPs) have been studied to demonstrate the intermolecular interactions of ZnO nanoparticles (NPs) suspension. Tryptophan (Tryp) was dissolved in water and used as dilute solution to study the dispersion of ZnO NPs in different concentrations (25 to 150 uM) with 25 step. Density p, apparent molar volume V®, refractive index (RI) nD and speed of light c have been reported. Man Singh equations were used to calculate the viscosity tj, surface tension y and friccohesity a, activation energy Ay*2 was calculated using Arrhenius equation on the basis of pendant drop number (PDN) and viscous flow time (VFT) which counted by Borosil ManSingh Survismeter (BMS) instrument for solutions at room temperature. The physicochemical properties revealed the effect of ZnO NPs concentration on intermolecular interactions in dispersion systems. The results depicted the strong role of Tryptophan on ZnO NPs dispersion process in the term of solute-solvent and solute-solute interactions and free chemical reaction suspension.

Electrochemical Evaluation of Folic Acid by Low Concentration of Methylene Blue Coated on a Green‐Synthesized ZnO Nanoparticles Suspension Solution

AbstractHere, we have reported an effective and simple electrochemical technique to determine folic acid (FA) in a colloidal suspension solution containing FeIII ion, methylene blue (MB) surface‐coated ZnO nanoparticles (MB@ZnONPs) and sodium dodecyl sulfate (SDS) (FeIII/MB@ZnONPs/SDS). MB, and ZnONPs were used as redox indicator and signal amplification element respectively. Low‐concentration of MB (2.5 μM) strongly is maintained at ZnONPs surface. SDS was used to improve the dispersion stability of the suspension. ZnONPs were synthesized through biological pathway using cordia myxa leaves extract. To investigate physicochemical properties of ZnONPs and MB@ZnONPs, fourier‐transform infrared spectra, nitrogen desorption/adsorption isotherms, field emission scanning electron microscopy and energy dispersive X‐ray spectroscopy were used. Cyclic voltammetry and differential pulse voltammetry showed the positive effect of FeIII ion, on the redox behavior of the suspension solution, probably due to inhibiting effect of this cation on the agglomeration of MB@ZnONPs/SDS suspension. Addition of FA to suspension solution, caused a sharp decrease in the peak current. Therefore, the colloidal suspension solution employed as an analytical probe for FA determination. The response of the probe showed a linear dependence on the logarithm of FA concentration in the range of 1.42 nm to 3.30 μM (I/μA=‐0.26 Log [FA]+0.03, R2=0.99). The calculated limit of detection was 0.98 nM.

Chronic sublethal effects of ZnO nanoparticles on Tigriopus fulvus (Copepoda, Harpacticoida).

This study investigated for the first time the effects of ZnO nanoparticle (NP) chronic exposure (28days) on Tigriopus fulvus. Acute toxicity (48h) of three Zn chemical forms was assessed as well including the following: (a) ZnO nanoparticles (NPs), (b) Zn2+ from ZnO NP suspension after centrifugation (supernatant) and (c) ZnSO4 H2O. Physical-chemical and electronic microscopies were used to characterize spiked exposure media. Results showed that the dissolution of ZnO NPs was significant, with a complete dissolution at lowest test concentrations, but nano- and micro-aggregates were always present. Acute test evidenced a significant higher toxicity of Zn2+ and ZnSO4 compared to ZnO NPs. The chronic exposure to ZnO NPs caused negative effects on the reproductive traits, i.e. brood duration, brood size and brood number at much lower concentrations (≥ 100μg/L). The appearance of ovigerous females was delayed at higher concentrations of ZnO NPs, while the time required for offspring release and the percentage of non-viable eggs per female were significantly increased. ZnO NP subchronic exposure evidenced its ability to reduce T. fulvus individual reproductive fitness, suggesting that ZnO NPs use and release must be carefully monitored. Graphical abstract Graphical Abstract.

Low- and high-order nonlinear optical studies of ZnO nanocrystals, nanoparticles, and nanorods

Variable shapes and sizes of the zinc oxide nanostructures attract the attention due to the peculiarities of their nonlinear optical properties. We report the second-, third-, and high-order nonlinear optical studies of ZnO nanostructures using 800 nm, 40 fs pulses. We analyze the second harmonic generation as a function of the energy of the 800 nm laser pulses irradiating ZnO nanostructures. The studied samples possess the quadratic dependence of the second harmonic yield at the variable intensity of laser radiation. The Z-scan studies of ZnO nanoparticles suspension using 400 nm probe pulses allow determining their nonlinear refractive index (4 × 10−11 cm2 W−1) and nonlinear absorption coefficient (8 × 10−7 cm W−1). We also analyze the optical limiting properties of ZnO nanoparticles suspension. The propagation of femtosecond pulses through the plasmas containing ZnO nanoparticles allowed generation of high harmonics up to the 29th order.

Antimicrobial potential of ZnO, TiO2 and SiO2 nanoparticles in protecting building materials from biodegradation

ZnO, TiO2 and SiO2 nanomaterials were prepared by chemical syntheses and tested for the antimicrobial activity. The phase composition and micromorphology of powder samples were evaluated with the use of XRD and TEM methods. The nanomaterial aqua suspensions with concentrations in the range from 0.01 to 0.25% were prepared and their bactericidal properties were evaluated by interaction with eight types of microorganisms most commonly affecting building materials: Bacillus subtilis, Aspergillus niger, Aspergillus terreus, Aureobasidium pullulans, Cladosporium cladosporioides, Penicillium ochrochloron, Trichoderma viride, Paecilomyces variotii. It is established that ZnO nanoparticles (particle size 2–7 nm) at a suspension concentration varying from 0.01 to 0.25% are the most efficient. In the interaction of microorgamisms with ZnO nanoparticle suspensions, the concentration of microorganisms decreases by 2–3 orders of magnitude depending on their type. The TiO2 and SiO2 nanoparticles demonstrated their low bactericidal activity in the day sun light. The results are promising for the application of ZnO nanomaterials in the creation of building materials and protective coatings that are resistant to biodeterioration.

ZNO Nanoparticles as a Model for Removal of Pharmaceutical Compounds (Vitamin B12)in the Presence of UVA Light

The photocatalytic degradation of an aqueous solution of Vitamin B12 drug has studied under different conditions in the presence of ZnO nanoparticles suspension. The effect of various parameters such as mass of ZnO, Vitamin B12 drug concentration and study Removal of a real sample (mixture of pharmaceuticals compounds) by using ZnO. Results showed that, the photo catalytic degradation process was high at the beginningT andT thenT decreasedT withT time.T TheT explainedT theT photoT catalyticT degradationT efficiency,T whichT wasT increasedT byT increasingT catalystT loadingT fromT 0.05T toT 0.2T g.T TheT degradationT efficiencyT decreasedT withT theT increaseT inT catalystT loading.T ResultsT alsoT showedT thatT theT rateT ofT photoT catalyticT degradationT wasT increasedT withT decreasingT VitaminT B12T drugT concentration.

Simulation Study of Nanoparticle–Polymer Organic Suspension Stability

AbstractThis study uses a Monte Carlo simulation method to evaluate the agglomeration behaviors of different ZnO nanoparticle and polymethacrylate hybrid suspensions in an organic solvent. Interaction energies are primarily from the steric layer on the particle surfaces. The effects of nanoparticle size, steric layer thickness, particle content, and total solids loading are evaluated based on the average agglomerate size and agglomeration rate. Smaller particle, thicker steric layer, lower particle content, and higher solids loading are desirable factors to stabilize a suspension. Agglomerate size and agglomeration rate increase continuously with increasing particle content in the hybrids from 1 to 50 vol%. A drastic transition from an unstable suspension to a stable suspension occurs when the total solids loading of the suspension increases to greater than 10 vol%. This work provides important guidance for co‐dispersing nanoparticles and dissolved polymer chains in organic solvents.

Increased antibacterial activity of ZnO nanoparticles: Influence of size and surface modification.

In the current study, the size and surface of ZnO nanoparticle (ZnO NP) suspensions and powders were finely controlled to evaluate their influence on the ZnO antibacterial activity against Staphylococcus aureus and Escherichia coli. The ZnO NP were prepared by the sol-gel method with different reaction times for NP size control and followed by the addition of (3-glycidyloxypropyl) trimethoxysilane (GPTMS) as a surface modifier. The ZnO NP were characterized by different techniques and the antibacterial activity was assessed through the minimum inhibitory concentration assay (MIC), minimum bactericidal concentration assay (MBC) and scanning electron microscopy (SEM). The ZnO NP exhibited significant antibacterial activity against Staphylococcus aureus. The NP size highly influenced the antibacterial activity, which increased with decreasing particle size. The small ZnO NP presented bactericidal activity whereas the largest showed bacteriostatic activity. The use of GPTMS, in general, led to increase of MIC and MBC. The formation of holes in the cell wall of Staphylococcus aureus was evidenced by SEM after contact between the bacteria and ZnO NP. The cytotoxicity assay showed that ZnO NP did not cause a loss of cell viability in the human keratinocyte cell line (HaCat) at the maximum concentration assessed. Thus, this study indicated that 5 nm ZnO NP modified by GPTMS has great potential for use as an inorganic antibacterial material.

Amino acids adsorption in differently aged and concentrated aqueous suspensions of ZnO and TiO2 nanoparticles

Amino acids may be effectively used for preventing aggregation of engineered nanoparticles (NPs) in aqueous suspensions. This paper is primarily focused on the influence of exposure duration and particles content on adsorption coefficient (Ads) for ZnO and TiO2 nanoparticles with an average size of 40-60 nm exposed to 2M aqueous solutions of glycine and L-glutamic acid. The value of Ads was estimated from surfactant concentration related to the intensity of infrared peak spectroscopy at 1300-1400 cm−1. It has been shown that in more concentrated suspensions (0.08-0.12 g/mL) Ads has ±5% fluctuation in measurement error’ interval, whereas in less concentrated systems (0.02-0.04 g/mL) 3…20 h exposure of NPs may result in slight desorption of surfactant as shown for ZnO NPs or total desorption of surfactant as shown for TiO2 NPs in glycine solutions. Six times decrease of 0.02 g/mL NPs concentration leads to Ads augmentation by 3-4 and 1.5-6 times, respectively, on ZnO and TiO2 nanoparticles. From a methodological view point, it has been concluded that in order to provide effective comparative study of NPs adsorption properties it is not reasonable to concentrate the NPs suspension more than 0.04 g/mL and it is better to expose them during 3 h in order to avoid surfactant desorption.

Antibacterial activity of ZnO nanoparticles: dependence on particle size, dispersion media and storage time

Zinc oxide nanoparticles have a high potential as novel antimicrobial products. In this study ZnO nanoparticles of various sizes: 20-100 nm (ZnO-1) and 50-300 nm (ZnO-2) have been examined. This paper presents the results of an integrated study of the influence of physicochemical properties such as particle size and concentration of the freshly prepared and 24-hour suspensions of ZnO nanoparticles (0. 001…1000 mg/L) in distilled water and in normal saline upon their toxicity against bacteria E. coli. Ionic solutions of ZnCl2 were used for comparison study. Fresh aqueous solutions of nanoparticles displayed the highest antibacterial effect (E. coli survival under 5 − 25%). Storage for 24 hours reduced the toxicity of all the samples. In normal saline solutions the toxicity of the studied nanoparticles decreased at concentrations below 10 g/L. In all cases ZnO-2 suspensions displayed lower toxicity levels, especially after ageing for 24 hours. Stability analysis showed that the highest antibacterial effect was produced by less stable solutions containing the largest aggregates. Thus, it has been shown that antibacterial effects of zinc oxide nanoparticles are affected by the size of particles and their aggregates in colloidal solutions, chemical composition of the media and the suspensions storage time. The obtained results can be used for creating new types of antibacterial products including phytoprotectors based on nano-sized zinc oxide particles as well as for development of methods to assess and predict toxicity of zinc-containing suspensions.

DEVELOPMENT OF TEXTILE FOR ANTI ULTRAVIOLET ROOF THROUGH APPLICATION OF ZnO NANOPARTICLE USING THE MODIFIED PADDING METHOD

Development of textile as a roof with durability against ultraviolet/UV radiation can be achieved through the application of ZnO nanoparticles as UV absorber. Immobilization of ZnO nanoparticles onto cotton roof fabric using modified pad-dry-cure method and evaluation of its durability under ultraviolet irradiation was carried out in this research. Research methods including preparation of ZnO nanoparticles suspension and padding process using pad-dry-cure machine with modification of padding-drying multiplied process cycle up to 2 cycles. Evaluation and testing have been done upon durability of nanoparticles attachment on fabric and tensile strength of fabric after UV irradiation. Homogenous ZnO nanoparticle distribution on fabric surface has been obtained by using PVA concentration of 10%. Rain shower test shows that the fabric treated with modified method has higher water rejection performance than that of fabric treated with conventional method, as well as has good durability of attachment. After 5 hrs of UV irradiation, reduction of tensile strength in fabric treated with modified method were found only 1.2% and 1.5% for warp and weft directions respectively, lower than that of fabric treated with conventional method with 1.4% and 1.7% of respective reduction in warp and weft directions

Comparison on the effects of water-borne and dietary-borne accumulated ZnO nanoparticles on Daphnia magna

Nanoparticles (NPs) can exert toxicity to aquatic animals through water and dietary exposure. However, little is known about the contribution of the two exposure pathways to the total toxicity of NPs to aquatic animals. In the present study, we fed Daphnia magna with ZnO NPs-accumulated-algae or directly exposed them to ZnO NPs suspension at the same Zn concentration. The body Zn concentrations were the same in both treatments, but the surface elastic modulus in the water-borne group was lower than that in the dietary-borne group, indicating more severe surface damage in the water-borne treatment. Total egg numbers of the first brood in both Zn treatments were significantly lower than the control, but they were not significantly different between the two treatments. However, the first brood in the water-borne treatment was distinctly delayed than that in the dietary-borne group. The dietary-borne treatment suppressed the expression of Hem and SOD genes. The water-borne treatment significantly suppressed the expression of Pro, SOD, VTG, but increased the GST expression. In particular, the expression of Pro, a gene functions in modulation of cell multiplication, was lower in the water-borne treatment, which might be related to the suppression of body growth in D. magna. The expression of SOD in the water-borne treatment decreased by about four times in comparison with the dietary-borne treatment, and the SOD enzyme activity of the water-borne treatment was significantly lower than that of the dietary-borne treatment. These results indicate that the two exposure routes have different targets and responding toxic mechanisms.