UVB Blocking Research Articles

Preparation of uniform lignin/titanium dioxide nanoparticles by confined assembly: A multifunctional nanofiller for a waterborne polyurethane wood coating

We report a facile synthesis for lignin/titanium dioxide (TiO2) nanoparticles (LT NPs) at room temperature by confining assembly of lignin macromolecules. The LT NPs had a uniform nanosize distribution (average diameter ∼ 68 nm) and were directly employed as multifunctional nanofillers to reinforce a waterborne polyurethane wood coating (WBC). X-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy revealed the mechanism by which formed TiO2 confined lignin assembly. The LT NPs considerably increased the tensile strength of a WBC film from 16.3 MPa to 28.1 MPa. The WBC–LT NPs exhibited excellent ultraviolet (UV) A and UVB blocking performances of 87 % and 98 %, respectively, while maintaining 94 % transmittance in the visible region. Incorporating LT NPs into the WBC enhanced the coating performance (the hardness, adhesion, and abrasion resistance) on wood substrates. A quantitative color and texture analysis revealed that the LT NPs increased the decorativeness of actual wooden products. After nearly 1800 h of UV irradiation, wood coated with the WBC–LT NPs exhibited good color stability, where the original color remained unchanged or even became brighter. In this study, value-added valorization of lignin is enabled by using organic–inorganic nanofillers and insights are gained into developing multifunctional WBCs.

Zn2SnO4 ternary metal oxide for ultraviolet radiation filter application: a comparative study with TiO2 and ZnO

ABSTRACT Ultraviolet (UV) radiation causes serious health risks. Inorganic metal oxides, such as titanium dioxide (TiO2) and zinc oxide (ZnO), have long been recognized for their effectiveness as UV radiation filters/blockers in sunscreen formulations. TiO2 and ZnO as UV-blocking materials have some limitations and issues such as producing harmful radicals and toxicity, respectively. As a result, there is a growing need to develop efficient and safe UV-blocking materials to overcome these limitations associated with the conventional TiO2 and ZnO materials. Zinc stannate (Zn2SnO4), as a ternary metal oxide, is expected to be a promising candidate due to its optical properties and potential for UV-blocking capability. This study presents a comprehensive investigation into the development and characterization of Zn2SnO4 as a potential alternative UV filter to TiO2 and ZnO. The fundamental characteristics, including structural, optical, and photocatalytic characteristics, as well as cell viability, were investigated for two Zn2SnO4 morphologies: cubic aggregate Zn2SnO4 nanoparticles (ZTO CANP) and Zn2SnO4 nanoparticles (ZTO NP), which were compared with the performance of TiO2 nanoparticles (TiO2 NP) and ZnO nanoparticles (ZnO NP). Interestingly, in addition to their promising UVB and partial UVA blocking properties, ZTO CANP and ZTO NP were found to be relativity photocatalytically inactive materials, which means they produce less free radical species as in the case of TiO2 NP, and they cannot be considered as toxic materials as in the case of ZnO NP. To the best of our knowledge, this is the first direct comparison study examining the performance of Zn2SnO4 ternary metal oxide for its potential use as a UV filter. Further research and optimization need to be conducted on these materials, particularly on ZTO CANP as a promising alternative UV filter.

Involvement of silver and palladium with red peanuts skin extract for cotton functionalization

A systematic study is currently demonstrated approach for approving the superior role of silver and palladium metallic particles in acting the role of mordant with acquiring the dyed cotton fabrics excellence in color fastness with additional functions of antimicrobial potentiality and UV-protection action. Whereas, samples were dyed with extract of red peanuts skin as natural textile colorant (RPN dye). The represented data revealed that, in absence of mordant, the samples treated with metal precursors prior to dyeing were exhibited with the excellent color strength, color fastness, antimicrobial action and UV-protection action. Color fastness (washing, rubbing and light fastness) was estimated to be in the range of very good–excellent. Sample pretreated with silver salt and dyed in the absence of mordant was graded with excellent UV-protection action (UPF 31.5, UVB T% 2.6% and UVB blocking percent 97.4%). Antimicrobial potency against E. coli, S. aureus and Candida albicans through inhibition zone and the reduction percent was approved to be in the range of excellence (93.01–99.51%) for the samples dyed in absence of mordant and pretreated with either silver or palladium precursors.

Efficient ultraviolet blocking film on the lignin-rich lignocellulosic nanofibril from bamboo

The ultraviolet (UV) blocking performance of current bio-based devices is always limited by delignification and exploited chemical treatment. Lignocellulosic nanofibril (LCNF) is a promising green alternative that could efficiently impede UV radiation. Herein, we proposed a robust LCNF film that achieved 99.8 ± 0.19 % UVB blocking, 96.1 ± 0.23 % UVA blocking, and was highly transparent without complex chemical modification. Compared to conventional lignin composites, this LCNF method involves 29.5 ± 2.31 % lignin content directly extracted from bamboo as a broad-spectrum sun blocker. This bamboo-based LCNF film revealed an excellent tensile strength of 94.9 ± 3.6 MPa and outstanding stability, adapting to the natural environment's variability. The residual hemicellulose could also embed the link between lignin and cellulose, confirming high lignin content in the network. The connection between lignin and hemicelluloses in the cellulose network was explored and described for the fibrillation of lignocellulosic nanofibrils. This research highlights the promising development of LCNFs for UV protection and bio-based solar absorption materials.

Chitosan-based multifunctional films reinforced with cerium oxide nanoparticles for food packaging applications

The current study discusses the use of nanoceria as a multifunctional filler in food packaging biopolymer films for the first time. Nanoceria was synthesized using co-precipitation method. Chitosan-based food packaging films incorporated with 1 wt% and 2 wt% nanoceria were prepared and characterized. The FTIR absorption spectra confirms the presence of hydrogen bonding between nanoceria and chitosan structure. The nanocomposite films displayed strong UV-A and UV-B blocking properties besides being mechanically strong, thermally stable and possessing high moisture barrier properties. Further, due to the switching of oxidation states by cerium between Ce3+ and Ce4+, nanoceria shows high photocatalytic activity. This results in strong antimicrobial activity against E. coli and L. monocytogenes, especially under visible light. Further, the nanocomposite films displayed ∼1.25 times and ∼2.3 times higher ABTS and DPPH free radical scavenging potential, respectively, compared to pristine chitosan films, which indicate their high antioxidant potential. Moreover, the films depicted good biocompatibility towards L929 cells indicating their safety for food contact applications. With all these properties, the nanoceria-added chitosan films display strong potential for use in active food packaging, especially for high fat food products such as nuts and meats.

Cellulose/Grape-Seed-Extract Composite Films with High Transparency and Ultraviolet Shielding Performance Fabricated from Old Cotton Textiles

Plastics displaying many merits have been indispensable in daily life and they still maintain the strong momentum of development. Nevertheless, petroleum-based plastics possess a stable polymer structure and most of them are incinerated or accumulated in the environment, leading to devastating impacts on our ecology system. Thus, exploiting renewable and biodegradable materials to substitute or replace these traditional petroleum-derived plastics is an urgent and important task. In this work, renewable and biodegradable all-biomass cellulose/grape-seed-extract (GSEs) composite films with high transparency and anti-ultraviolet performance were fabricated successfully from pretreated old cotton textiles (P-OCTs) using a relatively simple, green, yet cost-effective, approach. It is proved that the obtained cellulose/GSEs composite films exhibit good ultraviolet shielding performance without sacrificing their transparency, and their UV-A and UV-B blocking values can reach as high as nearly 100%, indicating the good UV-blocking performance of GSEs. Meanwhile, the cellulose/GSEs film show higher thermal stability and water vapor transmission rate (WVTR) than most common plastics. Moreover, the mechanical property of the cellulose/GSEs film can be adjusted by the addition of a plasticizer. Briefly, the transparent all-biomass cellulose/grape-seed-extracts composite films with high anti-ultraviolet capacity were manufactured successfully and they can be used as potential materials in the packaging field.

Biodegradable, Flexible and Ultraviolet Blocking Nanocellulose Composite Film Incorporated with Lignin Nanoparticles

The exploration of functional films using sustainable cellulose-based materials to replace plastics has been of much interest. In this work, two kinds of lignin nanoparticles (LNPs) were mixed with cellulose nanofibrils (CNFs) for the fabrication of composite films with biodegradable, flexible and ultraviolet blocking performances. LNPs isolated from p-toluenesulfonic acid hydrolysis was easily recondensed and deposited on the surface of composite film, resulting in a more uneven surface; however, the composite film consisting of CNFs and LNPs isolated from maleic acid hydrolysis exhibited a homogeneous surface. Compared to pure CNF film, the composite CNF/LNP films exhibited higher physical properties (tensile strength of 164 MPa and Young's modulus of 8.0 GPa), a higher maximal weight loss temperature of 310 °C, and a perfect UVB blocking performance of 95.2%. Meanwhile, the composite film had a lower environmental impact as it could be rapidly biodegraded in soil and manmade seawater. Overall, our results open new avenues for the utilization of lignin nanoparticles in biopolymer composites to produce functional and biodegradable film as a promising alternative to petrochemical plastics.

Analysis of Components and Properties of Extractives from Alnus cremastogyne Pods from Different Provenances.

Chemical components with anti-oxidant, anti-inflammatory, and anti-cancer properties extracted from Alnus bark and leaves have been extensively studied. However, less attention has been paid to extractives from Alnus pods, which are mostly treated as waste. Here, extractives of Alnus cremastogyne pods from 12 provenances in Sichuan Province were studied for high value-added utilization of Alnus waste. The extractives were analyzed by Gas Chromatography-Mass Spectrometer (GC-MS), Ultraviolet-visible spectroscopy (UV-Vis spectra), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity. A total of 58, 49, and 51 chemical components were found when the organic solvents of ethanol, petroleum ether, and ethyl acetate were used to collect extractives, respectively. These chemical components including Phytol, CIS-5,8,11,14,17-eicosapentaenoic acid, Germacrene D, Lupeol, and β-sitosterol, etc., have wide applications in the fields of pharmacy and cosmetics. Moreover, it was also found that extractives in ethanol and ethyl acetate had impressive UV resistance, especially for UV-C and UV-B blocking. The results showed that the maximum block ratio towards UV-C and UV-B could reach 99%. In addition, the ethanol extract showed good anti-oxidant activity with a maximum free radical scavenging rate of 96.19%. This comprehensive and systematic study on extractives from Alnus cremastogyne pods promotes the development of high-value utilization of Alnus components.

Flexible graphene oxide/polyacrylonitrile composite films with efficient ultraviolet shielding and high transparency for the protection of paper-based artifacts

Abstract Paper-based artifacts, such as ink and wash paintings, paper cuts, etc., when exposed in environment for a long time, are prone to embrittling, yellowing and ageing because of ultraviolet light and weather elements. In a museum, special measurements are adopted to avoid these damages, but for common households, a functional coating is a good solution. However, this is not an easy task as the coating must be removable and cannot damage the articles. Graphene oxide (GO) has the potential as ultraviolet shielding material for the protection of paper-based artifacts, but the application of monolithic GO coatings on paper-based artifacts is difficult. In this work, feasible GO/polyacrylonitrile composite films were prepared and their protection properties for rice paper were explored experimentally. When GO loading reached 2 %, the UV-A and UV-B blocking percentages of the film were 57.47 % and 70.86 %, respectively, with a visible light transmittance of 77.09 %. These films also performed good moisture resistance. With a good flexibility, they could be easily transferred onto and peeled off the rice paper surface without damaging the paper texture and patterns on it. These films basically meet the demand of paper-based artifacts protection.

Transparent cellulose-based bio-hybrid films with enhanced anti-ultraviolet, antioxidant and antibacterial performance

Developing the biodegradable and eco-friendly materials to substitute for the traditional petroleum-derived plastics is significant, and cellulose is the most promising candidate to replace petroleum-derived plastics. However, the high-cost dissolving pulps are still the major raw materials in industry. Moreover, the traditional cellulose materials lack functions, limiting their application and service life. Herein, multi-functional cellulose/tea polyphenols (TPs) bio-hybrid films were fabricated successfully via employing low-cost waste cotton textiles as cellulose source. It was found that the cellulose/TPs films displayed high anti-ultraviolet capacity and irradiation stability without sacrificing their transparency, and UV-A and UV-B blocking values can reach 85.08 % and 99.97 %. Besides, cellulose/TPs films show up to 63 % of radical scavenging activity and possess obvious antibacterial capacity, due to the copious phenolic hydroxyls within TPs. Hence, the cellulose/TPs bio-hybrid films with enhanced anti-ultraviolet, antioxidant and antibacterial performance were manufactured successfully, which demonstrated great potentials in packaging fields.

Evaluation of Ultrasonically ZnO Loading Effect on Photocatalytic Self-Cleaning, UV Protection and Antibacterial Activity of Plasma/Citric Acid-Activated Cotton Fabric.

Zinc oxide (ZnO) nanoparticles were loaded over non-thermal plasma (P1) and citric acid (P2)-functionalized cotton fabrics using a room temperature sonification process. The cotton samples were pretreated with dielectric barrier discharge (DBD) plasma and citric acid to introduce some reactive moieties on the fabric to enhance the adhesion power of ZnO nanoparticles with an average particle size of 41 nm. The nanoparticles were dispersed homogeneously on the surface of the P1 sample, which enhanced the antibacterial, UV protection and photocatalytic self-cleaning characteristics of ZnO-loaded fabric. The self-cleaning efficiency of P1 and P2 samples was measured to be about 77% and 63%, respectively. The inhibition zones of 5.5 mm and 5.4 mm were produced by sample P1 against E. coli and S. aureus bacteria, respectively, which were slightly higher than the inhibition zones produced by sample P2. The inhibition zone of the samples roughly decreased by 17% after performing 10 wash cycles. The unloaded cotton fabric had a UPF value of 70.02 units and blocking percentage of 70.92% and 76.54% for UVA and UVB radiations, respectively. The UVA-blocking capacity of samples P1 and P2 was 95.27% and 91.22, respectively. Similarly, the UVB blocking capacity was 94.11% and 92.65%, respectively. The pre-coating plasma treatment was found to be helpful in improving the UV-blocking ability of ZnO-loaded cotton fabric.

Optimized preparation of spruce kraft lignin/ZnO composites and their performance analysis in polyurethane films

Spruce kraft lignin (SKL) has received considerable attention in recent years for its application in the field of polymer materials. However, its structural complexity and polydispersity pose significant challenges for commercial applications. In this study, molecular structure models of acetone soluble kraft lignin (ASKL) and acetone insoluble kraft lignin (AIKL) were proposed based on quantitative calculations of the connection mode of functional groups and structural units. The lignin was modified by quaternization and synthesized in situ as lignin/ZnO composites. Based on the detailed characterization of the micromorphology and structure of the composites, waterborne polyurethane (WPU) films were optimally prepared using 0.6 wt% of the composites. The results showed that the composite films prepared from ASKL have the best UV-blocking performance and mechanical properties. The highest UVA and UVB blocking rates were 98% and 100%, respectively, and the highest tensile strength and elongation at break were 31.2 MPa and 732%, respectively. The differences in the structure and functional groups of the different types of SKL were accurately identified. ASKL is advantageous for the development of UV-blocking films because of its low molecular weight and the presence of abundant phenolic hydroxyl groups, which facilitate the formation of hydrogen bonds, improve the compatibility, and ensure uniform dispersibility. The results of this study are of practical importance in the field of nano-functional materials for the high-value application of industrial lignin.

Antioxidant and UV-Blocking Properties of a Carboxymethyl Cellulose-Lignin Composite Film Produced from Oil Palm Empty Fruit Bunch.

Oil palm empty fruit bunch (EFB) pulp with the highest cellulose content of 83.42% was obtained from an optimized process of acid pretreatment (0.5% v/v H2SO4), alkaline extraction (15% w/w NaOH), and hydrogen peroxide bleaching (10% w/v H2O2), respectively. The EFB cellulose was carboxymethylated, and the obtained carboxymethyl cellulose (CMC) was readily water-soluble (81.32%). The EFB CMC was blended with glycerol and cast into a composite film. Lignin that precipitated from the EFB black liquor was also incorporated into the film at different concentrations, and its effect on the UV-blocking properties of the film was determined. Interestingly, the EFB CMC film without lignin addition completely blocked UV-B transmittance. The incorporation of lignin at all concentrations significantly enhanced the UV-A blocking and other physical properties of the film, including the surface roughness, thickness, and thermal stability, although the tensile strength and water vapor permeability were not significantly affected. Complete UV-A and UV-B blocking were observed when lignin was added at 0.2% (w/v), and the film also exhibited the highest antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals with an half-maximal inhibitory concentration (IC50) value of 3.87 mg mL–1.

Composition, sun protective and antimicrobial activity of lipophilic bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) extract fractions

Berries of the genus Vaccinium found in bogs and forest of Northern Europe are a valuable source of biologically active substances containing sterols, unsaturated fatty acids, flavanoids, anthocyanins. The presence of these compounds provides various health benefits of berry use – treatment of urinary tract inflammation, controls levels of sugar in the blood, improves cardiovascular health and reduces negative effects of oxidative stress caused by free radicals. The studied bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea L.) lipids were fractionated using normal-phase chromatography and they were found to contain fatty acids (oleic, linoleic acid), sterols (β-sitosterol), isoprenoids (ursolic and oleanolic acid) and different long-chain aliphatic compounds. The prepared extract fractions were tested for their sun protective factor and antimicrobial activity. Fractions containing high concentrations of phenolic acids (cinnamic acid, benzoic acid) were shown to have potential UV-B blocking activity, whereas the fractions with high sterol content effectively inhibited the growth of tested bacteria. These findings are empirical for the creation of natural nutraceutical and cosmeceutical functional ingredients.

Natural lignocellulosic nanofibril film with excellent ultraviolet blocking performance and robust environment resistance

Due to the current state of ozone layer depletion and potential risk of skin cancer, researches on sustainable cellulose-based films with ultraviolet (UV) blocking capabilities has attracted widespread attention. However, pure cellulose-based film required UV absorbent to be incorporated because of its poor UV blocking ability. In this work, natural lignocellulosic nanofibril (LCNF) film was fabricated by vacuum filtration and pressing process without any complex chemical modification or adding UV absorbers. The residual lignin retained in LCNF was found to act as natural macro-molecular UV absorber. LCNF film with lignin content of 4.89–15.68% exhibited excellent thermal stability, and their UVA and UVB blocking were in the range of 81.4–99.5% and 96.7–100%, respectively. Moreover, LCNF film exhibited stable UV shielding performance under high temperature, UV irradiation, acidic or alkaline conditions, providing LCNF film with a long-term use capacity. Overall, LCNF film is more environmentally friendly and harmless, which shows high potentials in anti-counterfeiting materials, UV protection, and windshields for vehicles.

Highly transparent graphene oxide/cellulose composite film bearing ultraviolet shielding property

This work investigates the ultraviolet (UV) shielding property of composite films synthesized with graphene oxide (GO) nanosheets and regenerated cellulose. Regenerated cellulose was prepared from ZnCl2/CaCl2/GO solution. The GO sheets presented a homogenous dispersion in the film matrix. The incorporation of GO endows the cellulose films with improved UV shielding capacity. When GO loading reaches 2%, the UVA and UVB blocking percentages are 66.7% and 54.2%, respectively. Moreover, the composite films had excellent visible light transmittance. The resulting films possess promising applications as protective and packing materials.

Solar UV irradiation effects on photosynthetic performance, biochemical markers, and gene expression in highbush blueberry (Vaccinium corymbosum L.) cultivars

Solar UV irradiation allows life on Earth, but becomes harmful at high levels due to UV-B and UV-A irradiation, generating negative effects for all organisms, including plants. We determined the effects of solar UV irradiation on photosynthetic performance, biochemical markers, and gene expression in five-year-old plants of two highbush blueberry (Vaccinium corymbosum L.) cultivars, Legacy and Bluegold. Plants growing under field conditions were subjected to three solar UV irradiation filter treatments: UV-transmitting filter (+UV-A/B), UV-B blocking filter (-UV-B), and UV-A/B blocking filter (-UV-A/B) during two seasons. Net photosynthesis did not change among solar radiation filter treatments in either cultivar. Bluegold showed a significant reduction in stomatal conductance (gs) during both seasons under +UV-A/B compared to -UV-A/B (control treatment); while effective quantum yield (ΦPSII) and electron transport rate (ETR) did not change in Legacy, Bluegold showed a reduction in ΦPSII and ETR during the 2014 season. The highest significant increase (P ≤ 0.05) in total phenol concentration was observed in Bluegold (40%) under +UV-A/B in the 2013 season compared to Legacy. A similar tendency in flavonoids and anthocyanin was observed but in both seasons. In conclusion, an interaction genotype-environment was observed, where Legacy and Bluegold cultivars were differentially affected by solar UV irradiation and seasons in field conditions. Although Bluegold maintains CO2 assimilation, activating antioxidant defense, gene expression (MYBPA1, CHS, and F3’H) and metabolites (flavonoid and anthocyanins) to counteract +UV-A/B treatment, this cultivar was no able to reduce oxidative stress and to recover photochemical efficiency of PSII compared to Legacy. Our findings contribute to the understanding of blueberry responses to solar UV irradiation at physiological, molecular, and metabolite levels under field conditions.

Effects of solar UV-B radiation exclusion on physiology, growth and yields of taro (Colocasia esculenta (L.)) at different altitudes in tropical environments of Southern Ethiopia

Plants are sessile by nature, they have to be able to cope with exposure to many biotic and abiotic stress factors, including solar UV-B radiation. The degree of stresses varies with geographic locations. The impact of solar UV radiation on growth, physiology and yield of taro (Colocasia esculenta (L.)) at different altitudes under tropical environments was evaluated in Southern Ethiopia at 1500 m, 1800 m and 2200 m a.s.l. The experiment was conducted under open field conditions, and was compared to the yield of taro under UV-B blocking plastic film at every location. Four taro cultivars (‘Black’, ‘Boloso-1’, ‘Purple’ and ‘White’) were used as planting materials. Each treatment was planted using RCB design with three replications. The result indicates that leaf number, shoot number, leaf area and leaf area index under UV-B exclusion were found to be higher at higher elevation than either lower or middle elevation for ‘Boloso-1’ and ‘Black’ cultivars. Exclusion of UV-B spectrum from solar radiation improved the number of leaves and the leaf area index, for two cultivars: ‘Black’ and ‘Boloso-1’. Blocking UV-B radiation also significantly enhanced stomata conductance, photosynthesis rate stomata opening area, stomata number and dry matter in ‘Boloso-1’, compared to other cultivars. However, physiologically ‘Purple’ cultivar did not respond to solar UV-B irradiation. Among all the cultivars, ‘Boloso-1’ was found to be a good candidate for maximum corm size, marketable and maximum total yield production in all test locations irrespective of solar UV-B irradiation. In conclusion, vegetative growth of taro cultivars responded better to altitudinal variation than variability of UV-B irradiation. Whereas, physiological parameters like stomata number, stomata opening area, stomata conductance and photosynthesis of different taro cultivars responded stronger to the level of UV-B irradiation than the altitude.

In-Vitro cytotoxicity, antibacterial, and UV protection properties of the biosynthesized Zinc oxide nanoparticles for medical textile applications

Nowadays, medical textiles have become the most essential and developing part in human healthcare sector. This work was undertaken with a view to harness the bio-active macromolecules secreted by fungi e.g. proteins and enzymes in bio-synthesis of ZnO nanoparticles for multifunctional textiles such as antibacterial activity and UV protection with considering the cytotoxicity limitation. Herein, the isolated fungus, Aspergillus terreus, was allowed to produce proteins which has affinity to cape ZnO-NPs. Various factors affecting the behavior of the secreted proteins on the formed nanoparticles were investigated. Thorough characterizations of the protein capped ZnO-NPs were performed by the using of UV–Visible spectroscopy, transmission electron microscope (TEM) Fourier Transform-Infra Red (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis and Dynamic light scattering analysis (DLS). Prior treatment of cotton fabrics with ZnO-NPs, the cytotoxicity of the protein capped ZnO-NPs was examined. After that, the antibacterial activity of the ZnO-NPs before and after treating of cotton fabrics, besides, the UV-protection (UPF) properties were investigated. Results obviously demonstrated the ability of the bio-secreted protein to cape and reduce ZnO to spherical ZnO-NPs with particle size lied around 10–45 nm, as indicated form UV–vis., spectra TEM, Zeta sizer, FTIR and XRD. Regarding to the results of cytotoxicity, the treatment of the cotton fabrics with ZnO-NPs were performed at safe dose (20 ppm). At this dose, ZnO-NPs loaded samples exhibited reasonable antibacterial activity against both Gram positive and Gram negative bacteria; besides, good UV-protection with reasonable increase in UVA and UVB blocking values. Indeed, nanotechnology based microbiological active molecules opens up new opportunities for us to explore novel applications in terms of green technology.

Ultraviolet Protection Properties of Commercial Sunscreens and Sunscreens Containing Zno Nanorods

Zinc oxide nanorods were used as the main ultraviolet agent in the development of sunscreens. Four commercial sunscreens containing organic and inorganic UV agents were studied for their UV performances and SPF determinations. From FESEM and TEM micrographs of ZnO powder, the dominant structure was rod structure with width range 61-70 nm. Sunscreens containing different concentrations of ZnO nanorods were characterized using UV-Vis spectrophotometer and X-ray diffraction (XRD). The absorbance spectra for commercial sunscreens showed a good protection in range of UVB (280-320nm), while sunscreens containing 20-40% (weight percentage) of ZnO nanorods showed a greater UV absorbance in UVA and UVB (280-400 nm). The strong UVA absorbance of ZnO nanorod can offer extra UV protection for commercial sunscreens. The average crystallite sizes of the sunscreen samples calculated from the XRD spectra were in the range 45.27 to 47.36 nm. In vitro sun protection factor (SPF) method was carried out to determine the SPF value of sunscreen specimens. SPF values of sunscreens containing ZnO nanorods were 29.50 to 43.48, whereby these SPF values indicated more than 93% of UVB blocking capability. The SPF values found of commercial sunscreens were slightly different from the SPF values in the product labels. In conclusion, incorporation of ZnO nanorods into sunscreen can greatly enhanced the UV blocking performance of sunscreens.