Search

Today, diabetes mellitus is one of the most common diseases that affects the population on a worldwide scale. Patients suffering from this disease are required to control their blood-glucose levels several times a day through invasive methods such as piercing their fingers. Our NaGdF 4 : 5% Er 3+ , 3% Nd 3+ nanoparticles demonstrate a remarkable ability to detect D-glucose levels by analysing alterations in their red-to-green ratio, since this sensitivity arises from the interaction between the nanoparticles and the OH groups present in the D-glucose molecules, resulting in discernible changes in the emission of the green and red bands. These luminescent sensors were implemented and tested on paper substrates, offering a portable, low-cost and enzyme-free solution for D-glucose detection in aqueous solutions with a limit of detection of 22 mg/dL. With this, our study contributes to the development of non-invasive D-glucose sensors, holding promising implications for managing diabetes and improving overall patient well-being with possible future applications in D-glucose sensing through tear fluid., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Nanocellulose has received enormous scientific interest for its abundance, easy manufacturing, biodegradability, and low cost. Cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs) are ideal candidates to replace plastic coating in the textile and paper industry. Thanks to their capacity to form an interconnected network kept together by hydrogen bonds, nanocelluloses perform an unprecedented strengthening action towards cellulose- and other fiber-based materials. Furthermore, nanocellulose use implies greener application procedures, such as deposition from water. The surface chemistry of nanocellulose plays a pivotal role in influencing the performance of the coating: tailored surface functionalization can introduce several properties, such as gas or grease barrier, hydrophobicity, antibacterial and anti-UV behavior. This review summarizes recent achievements in the use of nanocellulose for paper and textile coating, evidencing critical aspects of coating performances related to deposition technique, nanocellulose morphology, and surface functionalization. Furthermore, beyond focusing on the aspects strictly related to large-scale coating applications for paper and textile industries, this review includes recent achievements in the use of nanocellulose coating for the safeguarding of Cultural Heritage, an extremely noble and interesting emerging application of nanocellulose, focusing on consolidation of historical paper and archaeological textile. Finally, nanocellulose use in electronic devices as an electrode modifier is highlighted., (© 2022 The Authors. ChemPlusChem published by Wiley-VCH GmbH.)

This study reports an economical and portable point-of-care (POC) monitoring device based on artificial multi-enzyme cascade systems for multiple detection purposes. The device was made up of a disposable three dimensional microfluidic paper-based analytical device (3D μPAD) with multiple detection zones and a smartphone readout. On-paper synthesis of a multifunctional mimetic composite, based on the CeO 2 nanoparticles embedded in the amino-functionalized Fe metal-organic frameworks (CeO 2 @NH 2 -MIL-88B(Fe)), for cascade reactions was the main achievement of this work. The 3D μPAD was applied for simultaneous quantification of glucose, fructose, sucrose and maltose, and the detection process consisted of the enzymatic reaction of each sugar by anchored enzymes on the metal-organic frameworks (MOF) and successive oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Utilizing the new artificial mimicking system improved the color development uniformity and resulted in a reliable detection tool, with excellent detection limits in the range of 20-280 μM. It was directly applied to analyze the sugars levels of human total blood, urine, semen, honey and juice samples with the relative errors of less than 7.7% compared with the HPLC method. The cost-effective and easy-to-use μPAD has a great potential to be used in either medical diagnostics or the food industry. Also, it can be considered as a competitive POC method for patients in disadvantaged communities or emergencies., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Luminescent quantum dot (QD) ink is currently a powerful tool for generating hidden information on paper substrates. Herein, we fabricated a nanohybrid ink of bacterial cellulose nanocrystal (BCNC) and UV-responsive ZnO QD via electrostatic self-assembly for improving solvent resistance and message encryption process. Under investigations on the printed areas, the nanohybrid can slightly infiltrate into the paper fibers and form a thin layer on the top of paper substrates, conferring an enhanced print permanence against wetting conditions while maintaining the daylight unobservability and its luminescent stability. The water resistance of the proposed nanohybrid ink enables developing a higher security level that the prints can be submerged in CuCl 2 aqueous solutions to quench the luminescent message. The concealed message can eventually be revealed under UV light again after submerging in EDTA solution. Our ZnO QD/BCNC nanohybrid with eco-friendly nature therefore exhibits great potential as security marking ink for counterfeit protection with sustainable uses., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A molecularly imprinted paper-based analytical device (MIP-μPAD) was developed for the sensing of bisphenol A (BPA). The platform was screen-printed onto a filter paper support, where the electrodes and the fluorescence μPADs were designed. Owing to its dual electrochemical and fluorescence responses, molecularly imprinted curcumin nanoparticles were used to sense BPA. The μPAD design was characterized by transmission electron microscopy, scanning electron microscopy, fluorescence spectroscopy, and electrochemical techniques. The sensor design comprised a wide linear range from 1 to 200 μg L -1 with limits of detection of 0.47 ± 0.2 and 0.62 ± 0.3 μg L -1 (LOD, S/N = 3) for electrochemical and fluorescence sensing, respectively. Furthermore, the system showed good analytical performance such as selectivity, stability, and reproducibility. The feasibility of the MIP-μPAD was demonstrated for the sensing of BPA in seawater, foods, and polycarbonate plastic packaged water with recovery values of 97.2 and 101.8%.

Cellulosic nanomaterials are in the focus of academia and industry to realize light-weight biobased materials with remarkable strength. While the effect is well known, the distribution of these nanomaterials are less explored, particularly for paper sheets. Here, we explore the 3D distribution of micro and nanosized cellulosic particles in paper sheets and correlate their extent of fibrillation to the distribution inside the sheets and subsequently to paper properties. To overcome challenges with contrast between the particles and the matrix, we attached probes on the cellulose nano/microparticles, either by covalent attachment of fluorescent dyes or by physical deposition of cobalt ferrite nanoparticles. The increased contrast enabled visualization of the micro and nanosized particles inside the paper matrix using multiphoton microscopy, X-ray microtomography and SEM-EDX. The results indicate that fibrillary fines enrich at pores and fiber-fiber junctions, thereby increasing the relative bonded area between fibers to enhance paper strength while CNF seems to additionally form an inner 3D network., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The major obstacle to developing nanozymes which are considered as promising alternatives to natural enzymes is their moderate performance, including poor affinity for substrates, low catalytic activity, and severe pH-dependence. To address these issues, herein, we synthesize ultrathin layered double hydroxide (LDH) nanosheets with a thickness of 1.4 nm and an average lateral size of 23 nm using a fast-precipitation method. Through the rational design of their compositions, it is found that NiMn LDHs exhibit the optimum peroxidase mimicking performance with excellent substrate affinity, high catalytic activity (a limit of detection (LOD) of 0.04 μM H 2 O 2 ) and robustness in a wide pH range (from 2.6 to 9.0), which is superior to that of natural horseradish peroxidase (HRP). The main active centers are identified as Mn sites because of their strong Lewis acidity and low redox potential. Furthermore, a series of disposable paper bioassays based on NiMn LDH nanozymes are designed and used for the highly sensitive detection of H 2 O 2 and ascorbic acid (AA).

The Phenylketonuria (PKU) is an inborn defect of phenylalanine (Phe) metabolism, in which Phe accumulated in the blood causing alterations at the central nervous system. Therefore, the detection of PKU is very important for the early diagnosis of PKU patients. However, existing tests for PKU are time-consuming and require high-resource laboratories. In this study, a novel paper-based biosensor based on phenylalnine ammonia lyase (PAL) hybrid nanoflowers was constructed that provides a semi-quantitative output of the concentration of Phe from urine samples. PAL@Ca 3 (PO 4 ) 2 hybrid nanoflowers (PAL@NF) were first prepared using PAL and Ca 2+ . Synthesis conditions of the PAL@NF on the formation of the PAL@NF were optimized. The PAL@NF exhibited 90% activity recovery under optimal condition. Compared with free PAL, the PAL@NF displayed good storage stability and increased tolerance to proteolysis. After five consecutive operating cycles, the PAL@NF still retained 73% of its initial activity, indicating excellent reusability. Furthermore, the paper-based biosensor was able to detect Phe concentration in urine samples, and exhibited good linearity to the Phe concentrations in the range from 60 to 2400 μM and the response time was only about 10 min. Therefore, the paper-based biosensor can be a promising candidate as a biosensor for the detection of PKU., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Fluorescent nanoparticles are widely exploited as probes in cell tracking, drug delivery systems and high-performance security devices nowadays. Herein, we report the synthesis of novel 7-acryloxycoumarin (7-AC) through modification reaction of 7-hydroxycoumarin with acryloyl chloride and its copolymerization with methyl methacrylate and glycidyl methacrylate to produce epoxy-functionalized fluorescent polymer nanoparticles through emulsion polymerization. Chemical modification of cellulose pulp papers with the as-prepared fluorescent latex nanoparticles was also assessed. Spherical nanoparticles with average particle size of 40-93 nm and their diffusion into cellulosic fibers with excellent wetting and coating were monitored. Fluorimetery analysis demonstrated that immobilization of 7-AC into the hydrophobic acrylic copolymer substrate enhanced its emission intensity significantly with respect to its molecularly solution due to the elimination of unwanted environmental effects and non-radiative processes such as probable internal conversions. The obtained products exhibited intensified fluorescence emission with potentiality of being used in anticounterfeiting inks and security documents., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Globally, rapid development of antibiotic resistance amongst pathogens has led to limited treatment options and high indirect costs to health management. There is a need to avoid misuse of available antibiotics and to develop rapid, affordable and accessible diagnostic technologies to detect drug resistance even in resource limited settings. This study reports the development of instrument-free point-of-care devices for detection of antibiotic resistance for rapid diagnosis of drug resistance in the penicillin, cephalosporin and carbapenem groups of antibiotics. The simple paper-based devices for flow through assay determine the presence of resistant bacteria in a sample by a visible colour change within 30 minutes. At the center of this technology is the unique sensing nanomaterial comprising of core-shell nanoparticles layered with specific antibiotics. The core is comprised of chitosan nanoparticles of size ∼15 nm coated with the starch-iodine indicator to form a shell increasing the size to ∼47 nm. The test strip is coated with the nanoparticles, air-dried and overlayed with the required antibiotic. In the presence of penicillin, cephalosporin and carbapenem resistant bacteria, the core-shell nanoparticles undergo a visible colour change from blue to white. The core-shell nanoparticles were deposited on paper to form a point-of-care device. Devices were developed to screen for three main classes of antibiotics namely penicillins, cephalosporins and carbapenems. The devices were validated using standard resistant and susceptible ATCC strains in three different sample types, pure colony, broth culture and saline suspensions. The change of colour from blue to white was considered a positive test. The time of detection was found to be 30 min, while the limit of detection was 10 5 cfu ml -1 . The device exhibited 100% sensitivity and specificity with known resistant and susceptible cultures not only from pure colonies but also from direct samples of spiked saline suspensions with graded confounding factors of albumin, glucose, and urea. The inter-device reproducibility and storage stability of the devices was established. The developed point-of-care devices have potential as screening devices for antimicrobial resistance.

As new infectious disease outbreaks become more likely, it is important to be able to develop and deploy appropriate testing in time. Paper-based immunoassays are rapid, cheap, and easy to produce at scale and relatively user friendly but often suffer from low selectivity and sensitivity. Understanding the molecular mechanisms of paper immunoassays may help improve and hasten development and therefore production and market availability. Here, we study how the behavior of nanoparticle-antibody immunoprobes in paper dipstick immunoassays is impacted by synthesis strategy and surface chemistry architecture. We conjugate gold nanoparticles to polyclonal anti-immunoglobulin G (IgG) and anti-zika NS1 antibodies by electrostatic adsorption and N -hydroxysuccinimide (NHS) and hydrazide (Hz) chemistries. The immunoprobes were used in paper immunoassays and the effective affinity for the antigen was quantified from the test line intensities, as well as the distribution of the immunoprobes throughout the strips. The results show that nanoparticle colloidal stability, both post synthesis and during antigen binding, is a key factor and affects immunoassay results and performance, often through reduction or loss of signal.

Lots of beetles, moths, and birds in the natural world present stunning unique structural colors as well as excellent hydrophobic performances. Herein, a novel bioinspired variable structural-color film with organic-solvent responsiveness and surface hydrophobicity was fabricated. Cellulose nanocrystals (CNCs) provided structural color with left-handed helicity. PEG-PPG-PEG triblock copolymers (PPPTCs) were blended with CNCs, giving rise to the organic-solvent-responsive structural color and wider red-shift window of the reflectance peak. The color of the film could be regulated repeatedly under the stimulus of cyclohexanone with an obvious red shift up to 107 nm, corresponding to a macroscopic color change from blue to yellow. Low-surface-energy compound hexadecyltrimethoxysilane (HDTMS) was covalently grafted on the surface in a one-step method to introduce hydrophobicity, successfully preventing the effect of water on the ordered nanostructure. Based on the bionics principle, the as-prepared CNC/PPPTC nanocomposite films with variable structural colors and hydrophobicity are beneficial to their prospective applications in display screens, rewritable hydrophobic structural-color-changing paper, biomimetic sensors, and so forth.

China, a big paper-making country, produced hundreds of millions of tons of waste paper which contain a lot of fiber every year. Cellulose nanocrystals were extracted from recycled waste paper which can be a high value utilization of secondary fiber. In this paper, cellulose nanocrystals were successfully extracted from waste paper fibers via two different systems, sulfuric acid hydrolysis (SCNCs) and one-step ammonium persulfate (APS) oxidation (OCNCs). This not only broadened the methods of extracting CNCs from waste paper, but also improved the dispersion and reactivity of CNCs. The CNCs products were investigated by FT-IR spectroscopy for functional group structure, X-ray diffraction for crystal structure, TG-DTG for thermal stability and scanning electron microscope, transmission electron microscope for morphology. The results showed that both OCNCs and SCNCs were a rod-like structure. The crystallinity of OCNCs and SCNCs increased to 72.45 and 77.56, but with a low yield of 22.42% and 41.22%, respectively. The result also suggested H 2 O 2 formed by decomposition of APS, selectively oxidized the hydroxyl on the C 6 in cellulose to carboxyl, introduced 0.57 mmol/g carboxyl. Successful preparation of CNCs extracted from waste paper can effectively utilize the fiber resources in waste paper, thus transforming into higher economic benefits., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Many lanthanide ions-based probes have been widely used for detecting anthrax spores biomarker-dipicolinic acid (DPA). However, little work has realized detection of bacillus anthrax spores in real environmental samples. In this work, a novel ratiometric fluorescent nanoprobe based on europium (Eu)-doped silicon nanoparticles (Eu@SiNPs) was fabricated for the first time by one-pot method without post-modification for determination of the DPA in bacillus subtilis spores (simulant bacillus anthrax spores). Based on Eu(III) in the Eu@SiNPs could be sensitized by DPA to emit intrinsic fluorescence and the fluorescence intensity of SiNPs in the Eu@SiNPs almost remained stable, a new ratiometric fluorescent method for determination of micro DPA in bacillus subtilis spores and bacillus subtilis spores in real environmental samples, such as Yellow river water, tap water and soil was established. Under the optimum conditions, the limit of detection (LOD) of the method toward bacillus subtilis spores was as low as 2.38×10 4 spore/mL. Simple, fast and visual DPA and bacillus subtilis spores determination was also achieved by the Eu@SiNPs-based test paper. Therefore, the newly established method was expected to be a powerful tool for efficiently determination of bacillus anthrax spores to avoid anthrax threats., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Petroleum-based plastics, such as PP, PE, PVC, etc., have become an important source of environmental pollution due to their hard degradation, posing a serious threat to the human health. Isolating nanocellulose from abundant biomass waste resources and further integrating the nanocellulose into hydrophobic transparent film (i.e., nanopaper), to replace the traditional nondegradable plastic film, is of great significance for solving the problem of environmental pollution and achieving sustainable development of society. This study respectively extracted nanocellulose from the branches of Amorpha fruticosa Linn., wheat straw, and poplar residues via combined mechanical treatments of grinding and high-pressure homogenization. Among them, the nanocellulose derived from the Amorpha fruticosa has a finer structure, with diameter of about 10 nm and an aspect ratio of more than 500. With the nanocellulose as building block, we constructed hydrophilic nanopaper with high light transmittance (up to 90%) and high mechanical strength (tensile strength up to 110 MPa). After further hybridization by incorporating nano-silica into the nanopaper, followed by hydrophobic treatment, we built hydrophobic nanopaper with transmittance over 82% and a water contact angle of about 102° that could potentially replace transparent plastic film and has wide applications in food packaging, agricultural film, electronic device, and other fields.

Salmon fish farmers face remarkable problems in fish rearing and handling due to the spread of disease by infectious pancreatic necrosis virus (IPNV). Therefore, we developed a straightforward and sensitive technique to detect IPNV-based on recombinant human apoferritin heavy chain (hAFN-H) protein nanoparticles. In this study, the 24 subunits of the hAFN-H were genetically modified to express 6×His-tag and protein-G at their C-terminal site using Escherichia coli . We thus achieved a two-step signal amplifying strategy that utilizes a recombinant hAFN-H nanoprobe having a protein-G-binding site that targets the F c region of monoclonal antibodies and a 6×His-tag that actively interacts with the functionalized Ni-NTA derivatives. In this study, we report a considerable advancement in magnetic bead-based detection systems that use Ni-NTA-Atto 550, reliably exhibiting detection limits of 1.02 TCID 50 /mL (50% tissue culture infective dose). Additionally, we propose a lateral flow chip-based detection method that uses the hAFN-H surface functionalized with 5 nm of the Ni-NTA-nanogold complex as a nanoprobe; the limit of detection towards IPNV was 0.88 TCID 50 /mL. The detection of IPNV by this recombinant hAFN-H nanoprobe was linear to virus titers in the range of 10 1 -10 3 TCID 50 /mL.

The rapid development of and the large market for medical diagnostics necessitate point-of-care testing (POCT) with superior sensitivity, miniaturization, multiple functionalities and high integration. Thus, flexible substrates with complex structures that provide multiple functions are in demand. Herein, we present multistructured pseudo-papers (MSPs) as a platform for building flexible microfluidics. Flexible and freestanding MSPs are generated by the self-assembly of colloidal silica crystals or core-shell copolymer elastic colloidal crystals on microcavity PDMS molds to form photonic crystals (PCs). Nitrocellulose (NC) multistructured pseudo-papers (NC MSPs) were obtained by etching SiO 2 PCs after NC precursor infiltration, while elastic copolymer (EC) multistructured pseudo-papers (EC MSPs) were directly peeled off the mold; both types of freestanding MSPs have ordered micropillars and nanocrystal structures and presented unique properties such as pumpless liquid transport and fluorescence and chemiluminescence (CL) enhancement. MSPs with designed patterns were fabricated by patterned PDMS molds, and complicated microfluidic chips were used to generate MSPs by utilizing these patterns as liquid channels. The MSPs were used for fabricating microfluidic sensors for human cardiac marker and cancer marker sensing; the features of these bioinspired MSPs indicate their potential for sensitive sensing, which will enable them to find broader applications in many fields.

The spherical cellulose nanocrystals (CNCs) with high purity were prepared, the processes included composite enzymolysis of pulp fibers and the purification of product. The impurities in the crude product CNCs were analyzed with FTIR, coomassie brilliant blue-G250 and ionic chromatography. The pure CNCs were characterized with SEM, XRD, DLS and TGA. The results indicated that the crude CNCs was flocculated and washed twice with a dilute acid solution (pH = 2) to get pure spherical CNCs, the purity was approximate 99.99%. The obtained pure spherical CNCs had a narrow particle size distribution with diameter 15-40 nm. FTIR and XRD analyses proved that the crystal phase of the spherical CNCs did not change, but the crystallinity decreased slightly compared with pulp fibers. The thermal degradation showed that the spherical CNCs had better thermal stability than one from other methods, and the temperature of maximum weight loss rate (T max ) was 329.2 °C., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

We report results of the studies relating to the fabrication of a label-free, flexible, light weight and disposable conducting paper based immunosensing platform comprising of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and nanostructured iron oxide (nFe 2 O 3 @PEDOT:PSS) nanocomposite for detection of carcinoembryonic antigen (CEA), a cancer biomarker. The effect of various solvents such as sorbitol, ethanol, propanol, n-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO) on the electrical conductivity of Whatman filter paper (WP) modified with nFe 2 O 3 @PEDOT:PSS/WP was investigated. The electrical conductivity of the PEDOT:PSS/WP electrode was found to be enhanced by two orders of magnitude (from 6.8× 10 -4 to 1.92 × 10 -2 Scm -1 ) after its treatment with DMSO. Further, nFe 2 O 3 doped PEDOT:PSS/WP electrode exhibited the electrical conductivity as 2.4 × 10 -2 Scm -1 . Besides this, the incorporation of iron oxide nanoparticles (nFe 2 O 3 ) into PEDOT:PSS/WP resulted in improved electrochemical performance and signal stability. This nFe 2 O 3 @PEDOT:PSS/WP based platform was used for immobilization of the anti-carcinoembronic antigen (anti-CEA) protein for quantitative estimation of cancer biomarker (CEA). The results of electrochemical response studies revealed that this conducting paper based immunoelectrode had a sensitivity of 10.2 μAng -1 mLcm -2 in the physiological range (4-25 ngmL -1 ) and shelf life of 34 days. Further, the proposed immunoelectrode was validated with conventional ELISA for the detection of CEA in serum samples of cancer patients., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Lateral flow biosensors are paper-based devices that allow the detection of different types of analytes with quickness, robustness and selectivity, without leaving behind paper sensors benefits as low-cost, recyclability and sustainability. Nanomaterials have been widely reported in lateral flow biosensors, offering new sensing strategies based on optical or electrical detection techniques. Looking for other advantageous nanomaterials, we propose for the first time the use of iridium oxide (IV) nanoparticles in lateral flow assays for the detection of human immunoglobulin as a model protein. These nanoparticles can be easily prepared and conjugated with biomarkers. Their dark blue color gives a high contrast against the white background of the strips being in this way excellent labels., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Paper-based sensors and assays have been highly attractive for numerous biological applications, including rapid diagnostics and assays for disease detection, food safety, and clinical care. In particular, the paper immunoassay has helped drive many applications in global health due to its low cost and simplicity of operation. This review is aimed at examining the fundamentals of the technology, as well as different implementations of paper-based assays and discuss novel strategies for improving their sensitivity, performance, or enabling new capabilities. These innovations can be categorized into using unique nanoparticle materials and structures for detection via different techniques, novel biological species for recognizing biomarkers, or innovative device design and/or architecture.

Filtration is a promising water treatment method to purify drinking water. To develop highly efficient drinking water filter paper, water-resistant cellulose foam paper with a high wet strength property was fabricated using diverse metal oxide (e.g., copper oxide (CuO), zinc oxide (ZnO), and silver oxide (Ag 2 O)) nanoparticles. These nanoparticles were synthesized using the hydrothermal reaction method. Their morphological structures were studied using a field emission scanning electron microscope (FESEM). The presence of coated nanoparticles on the cellulose foam filter was verified by energy dispersive X-ray spectroscopy (EDX) methods. The antibacterial performance of different types of modified cellulose foam filters was studied against E. coli, P. aeruginosa, B. subtilis, and B. cereus strains using the zone of inhibition test. The antibacterial profile of the cellulose foam filter impregnated with Ag 2 O nanoparticles, when tested against different types of bacteria, exhibited higher antibacterial activity than the cellulose foam filter impregnated with ZnO and CuO nanoparticles., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Point-of-care testing (POCT) devices represent a growing field that aims to develop low-cost, rapid, sensitive diagnostic testing platforms that are portable and self-contained. Surface-enhanced Raman spectroscopy (SERS) is an approach has shown high potential in POCT technology. However, the specificity or ability to uniquely detect a desired biomarker in complex biological samples is a key factor for translating SERS technologies to POCT. Herein, we fabricated cellulose SERS strips (CS) decorated with novel plasmonic nanoparticles, termed graphene-isolated-Au-nanocrystals (GIANs), for the portable detection of complex biological samples. This CS@GIANs SERS strip was used to detect free bilirubin (BR) in the blood of newborns, a biomarker of jaundice, without sample labeling or prepreparation. CS@GIANs showed superior affinity to hydrophobic BR molecules compared to typical SERS substrate, which reduced the steric hindrance effect from the nonspecific binding of BR with serum albumin in blood and improved sensitivity. Meanwhile, with the separation property of cellulose chromatography papers, CS@GIANs showed superior anti-interference to other biomolecules that had been previously adsorbed on the SERS strip. Moreover, the SERS signal from the graphitic shell of GIANs could be used as a stable internal calibration standard, which improved the reproducibility and accuracy of Raman analysis. Such a cellulose SERS strip holds high potential for enhancing current efforts in the development of rapid and low-cost point-of-care diagnostic testing.

In this Feature, the most recent developments as well as "pros and cons" in smartphone sensing, which have been developed using various functional nanoparticles in paper-based sensing systems, will be discussed. Additionally, smart phone sensing and POC combination as a potential tool that opens a gate for knowledge flow "from lab scale data to public use" will be evaluated.

In this work, a versatile point-of-care assay platform based on a microfluidic paper-based analytic device (μPAD) was developed for the simultaneous detection of multiple targets. The μPAD with a central zone and six test zones is fabricated by a simple and inexpensive wax printing method. A flower-like hybrid nanocomplex synthesized with specific dual enzymes and Cu3(PO4)2 inorganic nanocrystals is spotted in the test zones on the μPAD, followed by the introduction of assay targets. Using dual-enzyme inorganic hybrid nanoflowers in the μPAD as nanobiocatalysts, which preserve the activity and enhance the stability of the enzymes, based on the H2O2-mediated catalytic oxidizing chromogenic reaction produced by glucose/uric acid, the developed multiplex paper-based nanobiocatalytic system is demonstrated to enable simultaneous and sensitive detection of glucose and uric acid with a detection limit of 60 and 25 μM, respectively. More importantly, it has been successfully used for detecting glucose and uric acid levels in human whole blood samples. The developed multiplex paper-based nanobiocatalytic system features very easy fabrication and operation, low cost, and high sensitivity and has promising prospects for a clinical multianalyte point-of-care test.

Nowadays, environmentally friendly synthesis pathways for preserving the environment and minimizing waste are strongly required. Herein, we propose filter paper as a convenient scaffold for chemical reactions. To demonstrate this novel approach, Prussian Blue Nanoparticles (PBNPs) were synthesized on filter paper by utilizing few μL of its precursors without external inputs, i.e. pH, voltage, reducing agents, and without producing waste as well. The functional paper, named "Paper Blue", is successfully applied in the sensing field, exploiting the reduction of hydrogen peroxide at low applied potential. The eco-designed "Paper Blue" was combined with wax- and screen-printing to manufacture a reagentless electrochemical point-of-care device for diabetes self-monitoring, by using glucose oxidase as the biological recognition element. Blood glucose was linearly detected for a wide concentration range up to 25 mM (450 mg/dL), demonstrating its suitability for management of diabetes and glucose-related diseases. The Paper Blue-based biosensor demonstrated a correlation coefficient of 0.987 with commercial glucose strips (Bayer Contour XT). The achieved results demonstrated the effectiveness of this approach, which is also extendible to other (bio)systems to be applied in catalysis, remediation, and diagnostics., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Zika virus (ZIKV) is a reemerging flavivirus causing an ongoing pandemic and public health emergency worldwide. There are currently no effective vaccines or specific therapy for Zika infection. Rapid, low-cost diagnostics for mass screening and early detection are of paramount importance in timely management of the infection at the point-of-care (POC). The current Zika diagnostics are laboratory-based and cannot be implemented at the POC particularly in resource-limited settings. Here, we develop a nanoparticle-enhanced viral lysate electrical sensing assay for Zika virus detection on paper microchips with printed electrodes. The virus is isolated from biological samples using antibodies and labeled with platinum nanoparticles (PtNPs) to enhance the electrical signal. The captured ZIKV-PtNP complexes are lysed using a detergent to release the electrically charged molecules associated with the intact virus and the PtNPs on the captured viruses. The released charged molecules and PtNPs change the electrical conductivity of the solution, which can be measured on a cellulose paper microchip with screen-printed microelectrodes. The results confirmed a highly specific detection of ZIKV in the presence of other non-targeted viruses, including closely related flaviviruses such as dengue virus-1 and dengue virus-2 with a detection limit down to 101 virus particles per μl. The developed assay is simple, rapid, and cost-effective and has the potential for POC diagnosis of viral infections and treatment monitoring.

In this paper, a new and facile method for the electrochemical determination of l-tyrosine was designed. First, 3-mercaptopropyl trimethoxysilane-functionalized silica nanoparticles were added to a paper disc. Then, the banana peel tissue and the mediator potassium hexacyanoferrate were dropped onto the paper, respectively. The modified paper disc was placed on the top of the graphite screen printed electrode and electrochemical characterization of this biosensor was studied by cyclic voltammetry and electrochemical impedance spectroscopy methods. The effective parameters like pH, banana peel tissue percentage, and the amount of mediator loading were optimized. l-tyrosine measurements were done by differential pulse voltammetry with a little sample (3 μL) for analysis. The biosensor showed a linear response for l-tyrosine in the wide concentration range of 0.05-600 μM and a low detection limit about 0.02 μM because of the co-catalytic effect of enzyme and nanoparticles. The stability of the biosensor and its selectivity were evaluated. This biosensor was applied for the voltammetric determination of l-tyrosine in the blood plasma sample. The results of the practical application study were comparable with the standard method (HPLC). In conclusion, a simple, inexpensive, rapid, sensitive and selective technique was successfully applied to the l-tyrosine analysis of the little samples., (Copyright © 2018 Elsevier B.V. All rights reserved.)

High quantities of industrial wastewaters containing a wide range of organic and inorganic pollutants are being directly discharged into the environment, sometimes without proper treatment. Nanotechnology has a tremendous potential improving the existing treatments or even develop new treatment solutions. In this study, nano-TiO 2 or nano-Fe 2 O 3 was used for the photocatalytic treatment of kraft pulp mill effluent and mining effluent. The experiments with the organic effluent lead to reduction percentages of 93.3%, 68.4% and 89.8%, for colour, aromatic compounds and chemical oxygen demand, respectively, when treated with nano-TiO 2 /H 2 O 2 /UV and nano-Fe 2 O 3 /H 2 O 2 /UV, at pH 3.0. Significant removal of metals from the mining effluent was recorded but only for Zn, Al and Cd, the highest removal attained with 1.0 g L -1 of nano-TiO 2 /UV and nano-Fe 2 O 3 /UV. Regarding the toxicity of the organic effluent to Vibrio fischeri, it was reduced with the treatments combining the oxidant and the catalyst. However, for the inorganic effluent, the best reduction was achieved using 1.0 g L -1 of catalyst. In fact, the increase in dose of the catalyst, especially for nano-TiO 2 , enhanced toxicity reduction. Our results have shown that the use of these NMs seemed to be more effective in the organic effluent than in metal-rich effluent.

Flexible sweat biosensors are of considerable current interest for the development of wearable smart miniature devices. In this work, we report a novel type of flexible and electrochemical sweat platform fabricated by depositing Cu submicron buds on freestanding graphene paper (GP) carrying MoS 2 nanocrystals monolayer for bio-functional detection of glucose and lactate. Quantitative analysis of glucose and lactate was carried out by using amperometric i-t method. Linear ranges were obtained between 5 and 1775 μM for glucose and 0.01-18.4 mM for lactate, and their corresponding limits of detection were 500 nM and 0.1 μM, respectively. The platform demonstrates fast response, good selectivity, superb reproducibility and outstanding flexibility, which enable its use for monitoring glucose and lactate in human perspiration. The strategy of structurally integrating 3D transition metal, 0D transition metal sulfide and 2D graphene will provide new insight into the design of flexible electrodes for sweat glucose and lactate monitoring and a wider range of applications in biosensing, bioelectronics, and lab-on-a-chip devices., (Copyright © 2017. Published by Elsevier Inc.)

The present work describes the fabrication of an electrochemical paper-based analytical device (EPAD) integrated with Zn-Ag nanoblooms for detection of herpes in human, caused by Herpes virus 5(HHV-5) DNA, at the point of care. The cyclic voltammetry(CV) was used for electrochemical detection of the HHV-5 DNA in infected patient samples. The EPAD exihibited optimum current response within 5s at pH7.0 and 35°C with two dynamic linear/working ranges, 113-10 3 and 3×10 5 -10 6 copies/mL and detection limit of 97copies/mL. The device showed high selectivity, repeatability, and sensitivity. The device had many advantageous features such as portable, facile approach, economical and potential for commercialization. The proposed sensing scheme is highly feasible for future clinical detection of Herpes virus., (Copyright © 2017 Elsevier B.V. All rights reserved.)

An ultrasensitive paper based lateral flow assay is described for rapid and simultaneous fluorometric detection of several β-agonists including clenbuterol and its chemical analogues (mabuterol, brombuterol, cimaterol, cimbuterol, bromchlorbuterol and banbuterol). A nonspecific monoclonal antibody (mAb) against clenbuterol and its analogues was prepared and employed in a competitive immunoassay where mAb conjugated to fluorescent nanoparticles and free β-agonists compete for the binding sites. This enables rapid screening for the 7 β-agonists in a single run that takes about 8 min. Detection limits for the seven β-agonists are <50 pg g -1 of pork. Recoveries ranged from 69.5% to 102.4%, and relative standard deviations were ±15%. The assay was applied to the analysis of both using spiked and unspiked pork for β-agonists, and the results compare well to those obtained by HPLC-MS. Graphical abstractSchematic presentation of an ultra sensitive fluorescent nanoparticle based paper based assay for rapid detection of multi β-agonists in pork tissue., Competing Interests: Compliance with ethical standardsThe author(s) declare that they have no competing interests.

Herein, an environment friendly paper-based biobattery is demonstrated that yields a power of 12.5W/m 3 . Whatman filter papers were used not only as support for electrode fabrication but also as separator of the biobattery. To provide electrical conductivity to the paper-based cathode and anode, commercially available eyeliner containing carbon nanoparticles and Fe 3 O 4 was directly employed as conductive ink without any binder. With an instant start-up, the as-fabricated biocompatible electrodes could hold bacteria in an active form at the anode allowing chemical oxidation of organic fuel producing current. The facile process delineated here can be employed for the tailored electrode fabrication of various flexible energy harnessing devices., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A novel microfluidic paper-based analytic device (μPAD) biosensor is developed for sensitive and visualized detection of glucose. This biosensor is easily fabricated using the wax printing technique, with a hybrid nanocomplex composed of dual enzymes glucose oxidase (GOx) and horseradish peroxidase (HRP) and Cu 3 (PO 4 ) 2 inorganic nanocrystals incorporated in the detection zones. The hybrid nanocomplex is found to exhibit a flower-like structure, which allows co-immobilization of these two enzymes in a biocompatible environment. These nanoflowers not only preserve the activity and enhance the stability of the enzymes, but also facilitate the transport of the substrates between the two enzymes. The biosensor is demonstrated to enable rapid and sensitive quantification of glucose in the concentration range of 0.1-10 mM with a limit of detection (LOD) of 25 μM. It is also shown to be applicable to colorimetric quantitative detection of glucose in human serum and whole blood samples, implying its potential for clinical applications.

A new sensitive non-invasive gold nanoparticle-based sensor that enables to detect thiols in the human skin has been developed. The detection procedure implied the assessment of the color change of a paper sensor resulting from aggregation of gold nanoparticles caused by thiols. The ratio of the intensity of the photo image blue channel vs the red one (in units of RGB coloration) served as analytical response. The main thiol in the skin is glutathione, therefore, it was used as model biothiol and spiking substance. The range of linearity for glutathione was 8-75µM, the detection limit was 6.9µM. RSD≤7% is for inter-day determination of 10μM glutathione and RSD≤12% is the intra-day value. The recovery of 5µM and 10µM of glutathione was evaluated by applying solution, containing thiol-spikes, on skin. The results varied in the range 77-138%. A hundred-fold excess of serine, alanine, histidine, threonine, creatinine, urea, and ammonia; a ten-fold excess of glycine, proline, leucine, isoleucine, phenylalanine, asparagine; and a five-fold excess of valine, tryptophan, tyrosine, and uric acid, which can be extracted from the skin and is contained in the test matrix, have no significant effect on 10µM glutathione signal. Thiols level in the skin of volunteers (21-65 years old, men and women) detected with the use of a proposed non-invasive sensor was 11.6-47.5µM., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Quantum dots (QDs) and upconverting nanoparticles (UCNPs) are luminescent nanoparticles (NPs) commonly used in bioassays and biosensors as resonance energy transfer (RET) donors. The narrow and tunable emissions of both QDs and UCNPs make them versatile RET donors that can be paired with a wide range of acceptors. Ratiometric signal processing that compares donor and acceptor emission in RET-based transduction offers improved precision, as it accounts for fluctuations in the absolute photoluminescence (PL) intensities of the donor and acceptor that can result from experimental and instrumental variations. Immobilizing NPs on a solid support avoids problems such as those that can arise with their aggregation in solution, and allows for facile layer-by-layer assembly of the interfacial chemistry. Paper is an attractive solid support for the development of point-of-care diagnostic assays given its ubiquity, low-cost, and intrinsic fluid transport by capillary action. Integration of nanomaterials with paper-based analytical devices (PADs) provides avenues to augment the analytical performance of PADs, given the unique optoelectronic properties of nanomaterials. Herein, we describe methodology for the development of PADs using QDs and UCNPs as RET donors for optical transduction of nucleic acid hybridization. Immobilization of green-emitting QDs (gQDs) on imidazole functionalized cellulose paper is described for use as RET donors with Cy3 molecular dye as acceptors for the detection of SMN1 gene fragment. We also describe the covalent immobilization of blue-emitting UCNPs on aldehyde modified cellulose paper for use as RET donors with orange-emitting QDs (oQDs) as acceptors for the detection of HPRT1 gene fragment. The data described herein is acquired using an epifluorescence microscope, and can also be collected using technology such as a typical electronic camera.

This chapter describes two different methodologies used to improve the analytical performance of colorimetric paper-based biosensors. Microfluidic paper-based analytical devices (μPADs) have been produced by a stamping process and CO 2 laser ablation and modified, respectively, through an oxidation step and incorporation of silica nanoparticles on the paper structure. Both methods are employed in order to overcome the largest problem associated with colorimetric detection, the heterogeneity of the color distribution in the detection zones. The modification steps are necessary to improve the interaction between the paper surface and the selected enzymes. The enhanced performance has ensured reliability for quantitative analysis of clinically relevant compounds.

Polyaniline (PANI) with/without polystyrene (PS), was successfully manufactured in the occurrence of dispersed pulp fibers via the oxidative polymerization reaction of aniline monomer to produce conductive paper sheets containing PANI, PANI/PS composites. Additionally, sliver nitrate (Ag-NO3) was added by varied loadings to the oxidative polymerization of aniline monomer to provide sliver nanoparticles (Ag-NPs) emptied into the prepared paper sheets. The prepared paper sheets were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD) and infrared spectroscopy (IR), the mechanical properties of the prepared paper sheets were evaluated. Moreover, the electrical conductivity and biological studies such as cellulases assay, Microorganism & culture condition and detection of the released of Ag-NPs were evaluated. Furthermore, the prepared paper sheets were displayed good antibacterial properties contrary to gram positive and gram negative bacteria. Consequently, the prepared paper sheet may be used as novel materials for packaging applications., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Low cost paper based immunoassays are receiving interest due to their fast performance and small amounts of biomolecules needed for developing an immunoassay complex. In this work aggregation-induced emissive (AIE) nanoparticles, obtained from a diastereoisomeric mixture of 1,2-di-(4-hydroxyphenyl)-1,2-diphenylethene (TPEDH) in a one-step top-down method, are characterized through Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), and Zeta potential. By measuring the Zeta potential before and after labeling the nanoparticles with antibodies we demonstrate that the colloidal system is stable in a wide pH-range. The AIE-active nanoparticles are deposited on chitosan and glutaraldehyde modified paper pads overcoming the common aggregation-caused quenching (ACQ) effect. Analyte concentrations from 1000ng and below are applied in a model immunocomplex using Goat anti-Rabbit IgG and Rabbit IgG. In the range of 7.81ng-250ng, linear trends with a high R(2) are observed, which leads to a strong increase of the blue fluorescence from the TPEDH nanoparticles., (Copyright © 2016 Elsevier B.V. All rights reserved.)

For paper and paperboard packaging, recyclability plays an important role in conserving the resources and reducing the environmental impacts. Therefore, when it comes to the nano-enabled paper packaging material, the recyclability issue should be properly addressed. This study represents our first report on the fate of nanomaterials in paper recycling process. The packaging material of concern is a PLA (Polylactic Acid) coated paper incorporating zinc oxide nanoparticles in the coating layer. The material was characterised and assessed in a lab-scale paper recycling line. The recyclability test was based on a method adapted from ATICELCA MC501-13, which enabled to recover over 99% of the solids material. The mass balance result indicates that 86-91% zinc oxide nanoparticles ended up in the rejected material stream, mostly embedded within the polymer coating; whereas 7-16% nanoparticles ended up in the accepted material stream. Besides, the tensile strength of the recycled handsheets suggests that the nano-enabled coating had no negative impacts on the recovered fibre quality., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

An effective method of preparing composites containing inorganic (Ag) and organic (beeswax) particles was established in this study. Ag nanoparticles were first immobilized on the cellulose nanocrystals (CNC) during the reduction of AgNO3 in the presence of CNC, then mixed with beeswax by high speed stirring. Scanning transmission electron microscopy (STEM) images indicated that Ag and beeswax particles were uniformly dispersed and stable in the network structure formed by CNC. Upon coating on a paper surface, a layer of beeswax film was evident based on scanning electron microscopy (SEM) images. The dynamic contact angle and antibacterial activity tests indicated that the contact angle of coated paper reached 113.06° and the growth inhibition of Escherichia coli increased to 99.96%, respectively, at a coating amount of 21.53 g/m(2). When applied onto paper surface by coating, the CNC/Ag/beeswax composites can impact paper with antibacterial property and improved water resistance., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

We report the first use of a paper-based device coated with nanoceria as a simple, low-cost and rapid detection platform for the analysis of organophosphate (OP) pesticides using an enzyme inhibition assay with acetylcholinesterase (AChE) and choline oxidase (ChOX). In the presence of acetylcholine, AChE and ChOX catalyze the formation of H2O2, which is detected colorimetrically by a nanoceria-coated device resulting in the formation of a yellow color. After incubation with OP pesticides, the AChE activity was inhibited, producing less H2O2, and a reduction in the yellow intensity. The assay is able to analyze OP pesticides without the use of sophisticated instruments and gives detection limits of 18 ng mL(-1) and 5.3 ng mL(-1) for methyl-paraoxon and chlorpyrifos-oxon, respectively. The developed method was successfully applied to detect methyl-paraoxon in spiked vegetables (cabbage) and a dried seafood product (dried green mussel), obtaining ∼95% recovery values for both sample types. The spiked samples were also analyzed using LC-MS/MS as a comparison to the developed method and similar values were obtained, indicating that the developed method gives accurate results and is suitable for OP analysis in real samples.

Paper, a readily available renewable resource, comprises of interwoven cellulosic fibers, which can be functionalized to develop interesting low-cost adsorbent material for water purification. In this study, polyethyleneimine (PEI)-functionalized paper was used for the removal of hazardous pollutants such as Au and Ag nanoparticles, Cr(VI) anions, Ni(2+), Cd(2+), and Cu(2+) cations from spiked water samples. Compared to untreated paper, the PEI-coated paper showed significant improvement in adsorption capacities toward the pollutants investigated in this study. Kinetics, isotherm models, pH, and desorption studies were carried out to study the adsorption mechanism of pollutants on the adsorbent surface. Adsorption of pollutants was better described by pseudo-second order kinetics and Langmuir isotherm model. Maximum adsorption of anionic pollutants was achieved at pH 5 while that of cations was at pH>6. Overall, the PEI-functionalized paper showed interesting Langmuir adsorption capacities for heavy metal ions such as Cr(VI) (68 mg/g), Ni(2+) (208 mg/g), Cd(2+) (370 mg/g), and Cu(2+) (435 mg/g) ions at neutral pH. In addition, the modified paper was also used to remove Ag-citrate (79 mg/g), Ag-PVP (46 mg/g), Au-citrate (30 mg/g), Au-PVP (17 mg/g) nanoparticles from water. Desorption of NPs from the adsorbent was done by washing with 2 M HCl or thiourea solution, while heavy metal ions were desorbed using 1 M NaOH or HNO3 solution. The modified paper retained its extraction efficiencies upon desorption of pollutants., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Taking advantage of the self-assembly between the components, novel stable antibacterial nanoparticles were efficiently fabricated via a facile one-step co-polymerization of acrylic acid (AA) and N,N'-methylenebisacrylamide (MBA) on a mixed aqueous solution of poly(hexamethylene guanidine hydrochloride) (PHMG) and hydroxyethylcellulose (HEC). The z-average hydrodynamic diameters of the nanoparticles ranged from 220 nm to 450 nm. The inner layer of the nanoparticles is composed of water-insoluble interpolymer complexes of PHMG and PAA networks, while the outer layer is composed of PHMG and HEC. The nanoparticles are stabilized by electrostatic interactions, hydrogen bonding interactions, and the chemical bonds. The nanoparticle solution remained stable in a wide pH range of 2.0-12.0 and at salt concentrations below 0.25 mol/L. The nanoparticles were incorporated into handsheets using a dipping treatment. The resulted handsheets exhibited excellent antimicrobial activities even after multiple water washing treatments. The nanoparticles are promising in fabricating paper, water-based coatings and textiles with permanent antibacterial activity., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

In this study, we employed nanocrystalline cellulose (NCC) as an efficient dispersant to perpare alkyl ketene dimer (AKD) emulsion. The particle size and zeta potential of AKD/NCC emulsion were measured, which were approximately 5 μm and -50 mV, respectively. The surface-sized paper possessed multiple barriers properties. The air permeability of surface-sized paper was 0.29 μm/Pas and the sizing degree reached 42 s when the amount of sizing was 12.58 g/m(2) with a 96.83% decrease and a 40.00%, increase, respectively. Furthermore, the mechanical properties were optimal when the amount of sizing was about 8 g/m(2). AKD/NCC emulsion acted as a good reinforcing agent in surface-sized paper., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Spheres, tubes, and planar-shaped nanomaterials as Fe3O4 nanoparticles (MNPs), multiwalled carbon nanotubes (MWCNT), and graphene oxide (GO) were used for the first time to treat microfluidic paper-based analytical devices (μPADs) and create a biocompatible layer with high catalytic surface. Once glucose measurements are critical for diabetes or glycosuria detection and monitoring, the analytical performance of the proposed devices was studied by using bienzymatic colorimetric detection of this carbohydrate. The limit of detection values achieved for glucose with μPADs treated with MNPs, MWCNT, and GO were 43, 62, and 18 μM, respectively. The paper surface modification solves problems associated with the lack of homogeneity on color measurements that compromise the sensitivity and detectability levels in clinical diagnosis.

Photocopiers emit high levels of nanoparticles (PM0.1). To-date little is known of physicochemical composition of PM0.1 in real workplace settings. Here we perform a comprehensive physicochemical and morphological characterization of PM0.1 and raw materials (toners and paper) at eight commercial photocopy centers that use color and monochrome photocopiers over the course of a full week. We document high PM0.1 exposures with complex composition and several ENM in toners and PM0.1. Daily geometric mean PM0.1 concentrations ranged from 3700 to 34000 particles/cubic-centimeter (particles/cm(3)) (GSD 1.4-3.3), up to 12 times greater than background, with transient peaks >1.4 million particles/cm(3). PM0.1 contained 6-63% organic carbon, <1% elemental carbon, and 2-8% metals, including iron, zinc, titania, chromium, nickel and manganese, typically in the <0.01-1% range, and in agreement with toner composition. These findings document widespread ENM in toner formulations and high nanoparticle exposures are an industry-wide phenomenon. It further calls attention to the need to substantially redesign the interface of this technology with workers and consumers., (Copyright © 2015 Elsevier B.V. All rights reserved.)

This paper reports the continuous reductive amination of different molecules, including biomass-related compounds, over carbon-supported FeNi nanoparticles obtained on the basis of inexpensive and abundant metal precursors and cellulose. A biorefinery case study for the preparation of pyrrolidones via acid-catalyzed hydrolysis of glucose followed by reductive amination of the obtained levulinic acid is described., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Due to its amazing physicochemical properties and high environmental compatibility, cellulose nano-crystals (CNC) hold great promise for serving as a strategic platform for sustainable development. Now, there has been growing interest in the development of processes using waste or residual biomass as CNC source for addressing economic and environmental concerns. In the present work, a combined process involving phosphoric acid hydrolysis, enzymatic hydrolysis and sonication was proposed aiming to efficiently exact CNC from low-cost old corrugated container (OCC) pulp fiber. The effect of enzymatic hydrolysis on the yield and microstructure of resulting CNC was highlighted. Results showed that the enzymatic hydrolysis was effective in enhancing CNC yield after phosphoric acid hydrolysis. CNC was obtained with a yield of 23.98 wt% via the combined process with phosphoric acid concentration of 60 wt%, cellulase dosage of 2 mL (84 EGU) per 2g fiber and sonication intensity of 200 W. Moreover, the presence of enzymatic hydrolysis imparted the obtained CNC with improved dispersion, increased crystallinity and thermal stability., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Monodisperse aqueous upconverting nanoparticles (UCNPs) were covalently immobilized on aldehyde modified cellulose paper via reduction amination to develop a luminescence resonance energy transfer (LRET)-based nucleic acid hybridization assay. This first account of covalent immobilization of UCNPs on paper for a bioassay reports an optically responsive method that is sensitive, reproducible and robust. The immobilized UCNPs were decorated with oligonucleotide probes to capture HPRT1 housekeeping gene fragments, which in turn brought reporter conjugated quantum dots (QDs) in close proximity to the UCNPs for LRET. This sandwich assay could detect unlabeled oligonucleotide target, and had a limit of detection of 13 fmol and a dynamic range spanning nearly 3 orders of magnitude. The use of QDs, which are excellent LRET acceptors, demonstrated improved sensitivity, limit of detection, dynamic range and selectivity compared to similar assays that have used molecular fluorophores as acceptors. The selectivity of the assay was attributed to the decoration of the QDs with polyethylene glycol to eliminate non-specific adsorption. The kinetics of hybridization were determined to be diffusion limited and full signal development occurred within 3 min., (Copyright © 2015 Elsevier B.V. All rights reserved.)