Paper-Based Nanoplatforms for Multifunctional Applications

Chemical Communications, 2013

In this report, hierarchical ZnO nano and microstructures were directly grown for the first time in bacterial cellulose substrate and in other two different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures. Zinc oxide (ZnO) is an optoelectronic material with a plethora of applications in electronic and optoelectronic devices. ZnO is a distinguished material with some special properties owing to its wide direct bandgap (3.37 eV) and large excitation binding energy (60 meV) 1,2 , besides its excellent chemical and mechanical stability. ZnO nanostructures can be found in nanodevices, such as field-effect transistors 3 , lasers 4 , chemical and biological sensors 5 and dye-sensitized solar cells (DSSC) 6 . The interest in growing nanostructures on paper or paper-like substrates is mainly because of their low cost, environmentally friendly properties, biodegradability, recyclability, mechanical flexibility and compatibility with most printing processes 4 . These features are important for novel technologies such as smart cards, flexible displays 7 , solar cells 8 , especially organic photovoltaic solar cells 9,10 , electronic paper 11 , batteries 12 , capacitors and supercapacitors 13 . Bacterial cellulose (BC) has been utilized for developing bio-sensors 14 and organic light-emitting diodes (OLEDs) 15 . Bacterial cellulose can be produced from cultures of Gram-negative bacteria Gluconacetobacter xylinus, which produce highly hydrated membranes (up to 99% water), free of lignin and hemicellulose, as well as other biogenic products . Membranes produced in this way usually have a higher molecular weight and high crystallinity compared to the cellulose from plants. Bacterial cellulose membranes are characterized by a 3D structure consisting of an ultrafine network of cellulose nanofibers ("nanocellulose") . One of the pioneering contributions on the use of paper in electronic devices was reported by Fortunato and cols 20 who developed a transistor based on paper substrates with high performance 20 . Although papers based on cellulose are dielectric materials, in some cases, e. g. composites, it is possible to achieve electrical conducting characteristics.

… and Technology of …, 2010

Zinc oxide (ZnO) nanorods were grown on a paper support prepared from soft wood pulp. The photocatalytic activity of a sheet of paper with ZnO nanorods embedded in its porous matrix has been studied. ZnO nanorods were firmly attached to cellulose fibers and the photocatalytic paper samples were reused several times with nominal decrease in efficiency. Photodegradation of up to 93% was observed for methylene blue in the presence of paper filled with ZnO nanorods upon irradiation with visible light at 963 Wm -2 for 120 min. Under similar conditions, photodegradation of approximately 35% was observed for methyl orange. Antibacterial tests revealed that the photocatalytic paper inhibits the growth of Escherichia coli under room lighting conditions.

Green Chemistry, 2006

Coating of ZnO nanoparticles on paper surface has potential technological applications. With this motivation, a simple approach of ultrasound assisted coating of paper with ZnO nanoparticles (y20 nm) without the aid of binder is reported for the first time in this work. The ultrasound assisted coating approach concurs with ''green'' chemistry as it is simple and environmentally friendly. Scanning electron microscope is used to characterize the surface morphology showing ZnO nanoparticles bound to cellulose fibers. Further characterization of coated surface is performed by attenuated total reflectance-Fourier transform infrared, X-ray diffraction, and time-of-flight secondary ion mass spectrometry in positive ion detection mode along with its imaging capability. The effect of ultrasound irradiation time on ZnO nanoparticles loading is estimated by thermogravimetric analysis. A plausible coating mechanism is proposed. The ZnO nanoparticles coated paper is found to possess antibacterial activity against Escherichia coli 11634.

P apers are mainly used for printing and writing, and thereby, for storage and preservation of data and information. Other applications of paper include packaging, cleaning, decoration, filtration, and chromatography. Environmental effects, like attack by moisture, and microbial effects, like attack by bacteria and fungi, sometimes prevent storage of documents for long periods. Accidental spillage of water or coloring material may also lead to spoilage of the documents. Hence, development of water and stain-repellent paper, as well as antimicrobial paper, is in demand today. Semiconductors, such as zinc oxide (ZnO) and titanium dioxide (TiO 2 ), have photocatalytic characteristics, whereas their nanoparticles also have some water repellency and antimicrobial properties.

Cellulose Chemistry and Technology, 2021

We employed a microwave-assisted two-pot in-situ deposition technique to incorporate zinc oxide particulates in the structure of filter paper to produce antimicrobial paper. The process involved successive immersion of filter paper samples in ZnSO4 (precursor solution) and NaOH (precipitating agent) to form Zn(OH)2, which transformed into ZnO during microwave treatment. Successful deposition of ZnO particles on the filter paper was confirmed via X-ray diffraction and the corresponding morphologies were observed using field emission scanning electron microscopy. The ZnO-deposited papers were tested for antimicrobial activity and were found to be more effective against Staphylococcus aureus (gram-positive) than Escherichia coli (gram-negative). Bacterial populations were reduced by up to 92 ± 2% and 57 ± 4% for S. aureus and E. coli, respectively. Also, it was found that the samples prepared using higher concentrations of ZnSO4 and NaOH exhibited better antimicrobial properties.

Journal of Materials Processing Technology, 2010

Zinc oxide (ZnO) is a potential pigment material for paper coating to impart brightness and better printing properties. Nano-ZnO, due to its extremely small size, gives paper coating pigment a high covering power apart from antifungal and UVprotecting properties. In this work, zinc oxidesoluble starch nanocomposites (nano-ZnO) was prepared by a simple and novel wet chemical method using zinc nitrate and sodium hydroxide as precursors and soluble starch as stabilizing agent. Primary particle size distribution was extracted from small angle X-ray scattering (SAXS) measurements by the hard sphere model and calculated to have an average size of 4.1 nm. This nano-ZnO was coated on the surface of base paper (59 GSM) in a laboratory paper coater and their properties were studied. The brightness, whiteness, paper smoothness, print density, print uniformity, picking velocity and oil absorbency of

Journal of Materials Chemistry B, 2014

Small, carboxymethyl-starch-stabilised zinc oxide nanoparticles with a defined shape, size and morphology were prepared in situ in water at relatively low reaction temperatures using soluble carboxymethyl starch (CMS) as a combined crystallising, stabilising and solubilising agent and triethanolamine as the reducing agent. Aqueous colloidal solutions of these CMS-stabilised ZnO nanoparticles were used to deposit a coating of ZnO nanoparticles on cellulose paper by a wet-chemistry, polyelectrolyte, layer-by-layer approach using water as the only solvent. Such cellulose paper samples, coated with these CMSstabilised ZnO nanoparticles, show higher brightness and whiteness than that of blank reference paper and are more stable to UV-radiation than the paper reference as well as demonstrating good antibacterial activity against MRSA and A. baumannii.

Chemosensors, 2021

The fabrication of low-cost, flexible, and recyclable electronic devices has been the focus of many research groups, particularly for integration in wearable technology and the Internet of Things (IoT). In this work, porous zinc oxide (ZnO) nanostructures are incorporated as a UV sensing material into the composition of a sustainable water-based screen-printable ink composed of carboxymethyl cellulose (CMC). The formulated ink is used to fabricate flexible and foldable UV sensors on ubiquitous office paper. The screen-printed CMC/ZnO UV sensors operate under low voltage (≤2 V) and reveal a stable response over several on/off cycles of UV light exposure. The devices reach a response current of 1.34 ± 0.15 mA and a rise and fall time of 8.2 ± 1.0 and 22.0 ± 2.3 s, respectively. The responsivity of the sensor is 432 ± 48 mA W−1, which is the highest value reported in the literature for ZnO-based UV sensors on paper substrates. The UV-responsive devices display impressive mechanical end...

Materials

One of the main problems faced by libraries, archives and collectors is the mold degradation of the paper-based documents, books, artworks etc. Microfungi (molds) emerge in regular storage conditions of such items (humidity, usually over 50%, and temperatures under 21 °C). If the removal of the visible mycelium is relatively easy, there is always the problem of the subsequent appearance of mold as the spores remain trapped in the cellulosic, fibrillary texture, which acts as a net. Moreover, due to improper hand hygiene bacteria contamination, old books could represent a source of biohazard, being colonized with human pathogens. An easy and accessible method of decontamination, which could offer long term protection is therefore needed. Here, we present a facile use of the ZnO nanopowders as antimicrobial agents, suitable for cellulose-based products, conferring an extended antibacterial and anti-microfungal effect. The proposed method does not adversely impact on the quality of the...

Materials, 2017

In the present work, tracing and Whatman papers were used as substrates to grow zinc oxide (ZnO) nanostructures. Cellulose-based substrates are cost-efficient, highly sensitive and environmentally friendly. ZnO nanostructures with hexagonal structure were synthesized by hydrothermal under microwave irradiation using an ultrafast approach, that is, a fixed synthesis time of 10 min. The effect of synthesis temperature on ZnO nanostructures was investigated from 70 to 130 • C. An Ultra Violet (UV)/Ozone treatment directly to the ZnO seed layer prior to microwave assisted synthesis revealed expressive differences regarding formation of the ZnO nanostructures. Structural characterization of the microwave synthesized materials was carried out by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The optical characterization has also been performed. The time resolved photocurrent of the devices in response to the UV turn on/off was investigated and it has been observed that the ZnO nanorod arrays grown on Whatman paper substrate present a responsivity 3 times superior than the ones grown on tracing paper. By using ZnO nanorods, the surface area-to-volume ratio will increase and will improve the sensor sensibility, making these types of materials good candidates for low cost and disposable UV sensors. The sensors were exposed to bending tests, proving their high stability, flexibility and adaptability to different surfaces.