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Bio-based additives received significant attention in pulp and paper properties improvement. For this, the most cited biochemical Cellulose Nano Fibrils (CNFs) and Cationic Starch (CS) were experimentally compared with the most declared synthetic chemical, Cationic Polyacrylamide (CPAM). SEM images showed better paper surface filling by the utilization of the chemicals. The three studied polymers, in solely or combination mechanism, improved mainly bagasse pulp and paper properties compared to the blank sample, except for pulp drainage, which decreased by CNFs to lower volumes presumably due to its intrinsic characteristics. Cationic polymers (CP) compared to CP/CNFs approaches increased pulp retention and drainage but decreased paper density and strengths. The best pulp retention and drainage achieved by CS followed by CPAM, while paper air persistency, density, and strength properties evaluated highest by CP/CNFs followed by CNFs. Generally, CS revealed a more significant improvement in pulp and paper properties than CPAM either with or without CNFs.

As a crucial biomarker for some diseases, the determination of cholesterol in human serum is of great significance for the diagnosis and prevention of these diseases. Hence, a portable cholesterol detection method is necessary for clinical and domestic applications. Here, a portable paper sensor was designed for cholesterol detection by modifying screen-printed electrode (SPE) with nanoporous gold (NPG). To achieve the reliable cholesterol detection, a synergistic strategy was proposed based on the oxidation of cholesterol by cholesterol oxidase (ChOx) and the reduction of oxidation product (H2O2) by NPG. Compared to existing electrochemical sensors, the resulting paper sensor exhibited a wider linear response in a range from 50 μM to 6 mM as well as a higher sensitivity of 32.68 μA mM−1 cm−2 with a lower detection limit of 8.36 μM. Moreover, the portable paper sensor presented strong anti-interference capability and stability in the detection of cholesterol in human serum, and the data detected by the portable paper sensor were consistent with that obtained by an automatic biochemical analyzer. These unique performances confirmed that the proposed paper sensor was a sensitive, reliable, and portable cholesterol detection method, making it a good choice for cholesterol detection.

Funding Information: The financial support of the Austrian Federal Ministry of Digital and Economic Affairs and the National Foundation for Research, Technology and Development , Austria, is gratefully acknowledged. We also thank the industrial partners Mondi, Canon Production Printing, Kelheim Fibres, and SIG Combibloc for their support. Publisher Copyright: © 2021 Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Hydrophobization of cellulosic materials and particularly paper products is a commonly used procedure to render papers more resistant to water and moisture. Here, we explore the hydrophobization of unsized paper sheets via the gas phase. We employed three different compounds, namely palmitoyl chloride (PCl), trifluoroacetic anhydride/acetic anhydride (TFAA/Ac2O)) and hexamethyldisilazane (HMDS) which were vaporized and allowed to react with the paper sheets via the gas phase. All routes yielded hydrophobic papers with static water contact angles far above 90° and indicated the formation of covalent bonds. The PCl and TFAA approach negatively impacted the mechanical and optical properties of the paper leading to a decrease in tensile strength and yellowing of the sheets. The HMDS modified papers did not exhibit any differences regarding relevant paper technological parameters (mechanical properties, optical properties, porosity) compared to the non-modified sheets. XPS studies revealed that the HMDS modified samples have a rather low silicon content, pointing at the formation of submonolayers of trimethylsilyl groups on the fiber surfaces in the paper network. This was further investigated by penetration dynamic analysis using ultrasonication, which revealed that the whole fiber network has been homogeneously modified with the silyl groups and not only the very outer surface as for the PCl and the TFAA modified papers. This procedure yields a possibility to study the influence of hydrophobicity on paper sheets and their network properties without changing structural and mechanical paper parameters.

There is growing demand for simple to operate, sensitive, on-site quantitative assays to investigate concentrations of drug molecules in pharmaceutical preparations for quality assurance. Here, we report on the development of two colorimetric analysis methods for the study the antibiotic doxycycline hyclate (DOX) and the nasal decongestant oxymetazoline hydrochloride (OXY), in solution as well as in their respective formulations. We compare a UV/vis spectrophotometry method with a color change recorded on a microfluidic paper-based analytical device (μPAD). Detection is based on the pharmaceutical compounds coupling with diazotized 4-aminoacetophenone (DAAP) under alkaline conditions to produce colored azo-dye products. These azo-compounds were monitored by absorbance at 425 nm for DOX and 521 nm for OXY, with linear calibration graphs in the concentration range of 0.5–35 mg L−1 (DOX) and 1.0–40 mg L−1 (OXY) and limits of detection of 0.24 mg L−1 (DOX) and 0.32 mg L−1 (OXY). For the μPAD method, color intensity was measured from photographs and a linear increase was observed at concentrations from above approximately 15 mg L−1 for both compounds and up to 35 mg L−1 for DOX and 40 mg L−1 for OXY. The developed methods were also applied to the formulated pharmaceuticals and no interference was found from the excipient. Thus, the paper-based device provides an inexpensive, simple alternative approach for use outside centralized laboratories with semi-quantitative capability.

There is a pressing need around the world to develop novel functional biodegradable materials to separate oil/water mixtures and emulsions completely. Recently, superhydrophilicity and underwater superoleophobicity materials have been attracted attention due to their high efficiency in oil/water separation. However, it is still a challenge to prepare materials that combine oil/water separation and water purification in an environment-friendly way. In this work, biodegradable starch-based nanospheres (SNPs) coated filter paper was prepared in a low-cost, simple, and environmentally friendly manner. The SNPs coating could not only help to change the wettability of the substrate material but also build the hierarchical micro and nano structures which are conducive to separation and purification process. After modification by coating SNPs, the filter paper exhibited excellent performance in a wide range of oil/water mixtures or emulsions separation and the wettability of the filter paper could be regulated by adjusting the pH value. The modified filter paper presented good recyclability after several separation process. Furthermore, the as-prepared filter paper could also remove water-soluble contaminants during the oil/water separation process, thus realizing to combine separation and purification process in one single step. This biodegradable starch-based separating material with good separation performance, stability and recyclability has significant application potential in practical separation and purification process.

In this work, we prepared novel cellulosic paper by incorporating tannin into the kraft pulp for potential application in active food packaging. The kraft pulp fibers were firstly periodate oxidized to obtain the dialdehyde cellulosic fibers, and then reacted with varied dosages of tannin to incorporate them into the fibers by covalent bondings between aldehyde groups on cellulose and active hydrogen on tannin. Handsheets were prepared using the tannin incorporated fibers through papermaking process and the properties were characterized. The percentage of tannin in the paper increased with the increase of the tannin dosage. FT-IR spectra confirmed the successful incorporation of tannin into the cellulosic fibers. It was found that paper after incorporation of tannin turned to be surface hydrophobic with contact angles higher than 90°, which may probably due to the covalent bonds between tannin and cellulose. The handsheets show high antioxidative and UV-shielding properties, which both increased with the increase of the tannin percentage in the paper. Water vapor transmission rate (WVTR) decreased after the incorporation of tannin, and this could facilitate its application in food packaging. The breaking length of tannin incorporated paper decreased insignificantly, less than 10% with the tannin percentage as high as 45%.

Starch and derivatives thereof have proven their usefulness in paper coating processes. Among these derivatives, cationic starch has been widely used in the paper industry as a flocculation, dispersion and ink fixing agent. In another context, nanoscale cellulosic materials have been shown to improve the strength, retention of fillers, the barrier properties of packaging paper products, and printing qualities. This review summarizes the recent studies on the general components used in paper coating, describes the conventional and alternative synthetic processes of cationic starches and nanocellulose, and deals with their current and potential applications in papermaking, focusing primarily on surface treatments. Moreover, environmental applications have been considered to expand the understanding and usefulness of these materials. Further research on modified polysaccharides is encouraged to replace, in a feasible way, petro-based components of coating formulations, and to provide paper surfaces with new properties.

Xenoestrogens exert antiandrogenic effects on the human androgen receptor. In the analytical field, such antagonists block the detection of testosterone and falsify results obtained by sum parameter assays. Currently, such agonistic versus antagonistic effects are not differentiated in complex mixtures. Oppositely acting hormonal effects present in products of everyday use can only be differentiated after tedious fractionation and isolation of the individual compounds along with subjection of each fraction/compound to the status quo bioassay testing. However, such long-lasting procedures are not suited for routine. Hence, we developed a fast bioanalytical tool that figures out agonists versus antagonists directly in complex mixtures. Exemplarily, 8 cosmetics and 15 thermal papers were analyzed. The determined antagonistic potentials of active compounds found were comparable to the ones of known antagonists (in reference shown for bisphenol A, 4-n-nonylphenol and four parabens). Relevant biological/chromatographic parameters such as cell viability, culture conditions, dose response curves, limits of biological detection/quantification and working range (shown for testosterone, dihydrotestosterone, nandrolone and trenbolone) were investigated to obtain the best sensitivity of the biological detection. The developed and validated method was newly termed reversed phase high-performance thin-layer chromatography planar yeast ant-/agonistic androgen screen (RP-HPTLC-pYAAS bioassay). Results were also compared with the RP-HPTLC-Aliivibrio fischeri bioassay (applied on RP plates for the first time). As proof-of-concept, the transfer to another bioassay (RP-HPTLC-pYES) was successfully demonstrated, analogously termed RP-HPTLC-pYAES bioassay detecting anti-/estrogens (exemplarily shown for evaluation of 4 pharmaceuticals used in breast cancer treatment). The new imaging concept provides (1) detection and differentiation of individual agonistic versus antagonistic effects in the bioprofiles, (2) bioanalytical quantification of their activity potential by scanning densitometry and (3) characterization of unknown bioactive compound zones by hyphenation to high-resolution mass spectrometry. Depending on the hormonal bioassay, 15 samples were analyzed in parallel within 5 h or 6 h (calculated as 20 or 24 min per sample). For the first time, piezoelectric spraying of the yeast cells was successfully demonstrated for the planar yeast–based bioassays.

A sonication of graphite in polysaccharide (pullulan, chitosan and alginate) is one of the viable methods for the preparation of few-layer graphene. However, the effect of these adsorbed polysaccharides on the electrical performance of the produced graphene so far is not yet clear. In order to investigate the present effect of pullulan, chitosan and alginate on the electrical characteristic of resulted graphene, we have produced few-layer graphene using bath sonication of graphite in pullulan, chitosan and alginate medium for the application as electrical conductive ink in strain-sensitive. Data from the TEM reveals the appearance of folded few-layer graphene flakes after sonication for 150 min while the XPS data shows that the chitosan-based graphene possesses the highest carbon-oxygen ratio of 7.2 as compared to that of the pullulan and alginate-based graphene. By subjecting the produced graphene as the ink for paper-based strain sensor, we have discovered that the chitosan-graphene has the best resistivity value (1.66 × 10-3 Ω⋅cm) and demonstrate the highest sensitivity towards strain (GF: 18.6). This result interestingly implies the potential of the reported chitosan-based conductive ink as a strain-sensitive material for future food packaging.

Polygalacturonase (PG) activity in plants can serve as an important index for plant disease. However, the conventional method to detect PG activity is a complex process and requires a skilled technician and expensive analytical equipment. In this study, a paper-based colorimetric sensor was developed based on the principle of the ruthenium red (RR) dye method for easy and simple measurement of PG activity. The proposed paper-based sensor has a three-layer structure for detection of PG activity in samples. The sensor sensitivity was enhanced by optimizing the pH of the sodium acetate buffer used in polygalacturonic acid (PGA)-RR complex formation and the reaction temperature for PG and the PGA-RR complex. Further, for quantitative analysis of PG activity, Delta RGB analysis was conducted to detect color changes in the sensing window of the sensor. Results presented that the linear measurement range of the paper sensor was 0.02-0.1 unit with the limit of detection of 0.02 unit, which showed a similar detection range, but a lower detection limit, compared to the spectrophotometry. Furthermore, PG activity based on culture condition was measured using samples from Sclerotium cepivorum to verify the potential application of the developed paper-based sensor in the field. The measured activity showed no statistically significant difference from the values obtained from the spectrophotometry at 95% confidence level. Therefore, the paper-based colorimetric sensor can be used to predict plant diseases in Allium crops during the stage of pathogen invasion, potentially contributing to the improvement of crop production.

In this paper, nanochitin was used as an alternative natural nanomaterial to combine with cellulose fibers for fabricating high-strength paper. Two typical chitin nanowhiskers having contrasting sign of surface charge were compared to evaluate the enhancement performance on paper in details. The results show that nanochitin with positive charges on the surface has a significant effect on the strength properties of the prepared paper, especially on wet strength. When the dosage of chitin nanowhiskers was 2%, the wet strength index was increased to 2.48 N·m/g, which is important for paper-based analytical devices with the common use in liquid analysis. Typical colorimetric glucose assays were successfully performed, suggesting the improved analytical performance on these prepared paper.

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 H2O2 formed by decomposition of APS, selectively oxidized the hydroxyl on the C6 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.

Paper-based microfluidic device was designed with wax-printing to combine potentiometric, fluorimetric and colorimetric detection zones. This newly developed trimodal paper chip has been used for on-site determination of ketamine hydrochloride (KET) as a date rape drug in beverages. The device employed polyaniline nano-dispersion as conducting polymer in ion sensing paper electrodes designed to fit USB plug connector. Carbon dots-gold nanoparticles and cobalt thiocyanate were used in fluorescence and color detection zones, respectively. Cellular phone's camera facilitated the on-site fluorimetric and color detection. The implemented trimodal detection system exhibited specificity for KET detection in the presence of several other beverage interferences i.e., biogenic amines. This innovative sensor brings together analytical figures of merit for effective KET detection in single aliquot of spiked beverages. The proposed paper-based chip also fulfils WHO criteria for point-of-care devices posing the proposed trimodal paper device as an active part for rapid, on-site drug diagnostics and to be applied further for other similar drugs.

Free proline, termed proline, is a biomarker used for diagnosing drought stress in plants. A previously developed proline–ninhydrin reaction-based paper sensor could quickly and easily detect proline, but it was limited by low sensitivity. In this study, we developed an enclosed multilayer paper-based microfluidic sensor with high sensitivity for the quantitative detection of proline in plants. The multilayer paper-based sensor was manufactured using simple wax printing and origami methods, and contained an internal mixing channel to allow good mixing of the proline with ninhydrin, increasing the proline–ninhydrin reactivity and providing accurate and sensitive proline detection. By preloading ninhydrin onto the sample loading area, uniform coloration of the sensing window was achieved, allowing quantitative analysis of various proline concentrations using a constant reaction time. Only the sensing window and sample loading area were exposed to limit sample evaporation and contamination from the external environment. The LOD of the fabricated sensor was 23 μM, which is approximately 29-fold lower than that of the previously proposed paper sensor (657 μM). Samples were extracted from A. thaliana plants subjected to drought stress for proline detection. The proline concentrations measured using the developed paper sensor and a spectrophotometric method were not statistically significant at a confidence level of 95%. Therefore, the developed sensor can be applied to measure proline concentrations precisely in the field with a low detection limit. The developed paper-based sensor can be used to detect the early stages of drought in plants and thus improve crop productivity.

The incompatibility of most organic solvents with acetylcholinesterase (AChE) inhibition assay normally limits pesticide extraction efficiency in sample pretreatment, which might cause false negatives in real world sample assessment. Herein, a novel method has been developed for an improved AChE inhibition assay via organic solvent extraction combined spontaneous in situ solvent evaporation on microfluidic paper-based analytical devices. Enzyme pre-immobilization procedure was spared and AChE was added to the system after sampling step until a complete in-situ solvent evaporation process was performed on chip. IC50 levels of the six investigated organophosphate and carbamate pesticides indicated a completely eliminated influence of solvents on AChE behavior with the new method. Most importantly, analytical performances were significantly improved in food sample measurements. Reduction in matrix effect was observed when acetonitrile was adopted for lettuce sample pretreatment instead of water. Studies on different pesticides suggested a remarkably decreased discrimination effect on recoveries from sample pretreatment with the new developed method. The recovery level for phoxim spiked head lettuce samples reached (107.5 ± 14.2) %, in comparison with that of (18.6 ± 1.4) % from water-based extraction. Spiked water and apple juice samples with carbaryl concentration of as low as 0.02 mg L−1 were also successfully recognized with the present method by visual detection. This is the first report on direct sampling of organic extracts for AChE inhibition assay on-chip and it might provide a new perspective for real world sample assessments involving bio-reagents.

Problems of stability were found for biomarkers of alcohol consumption: ethyl glucuronide (EtG), ethyl sulfate (EtS), phosphatidylethanols (PEths), and fatty acid ethyl esters (FAEEs) in whole blood. The purpose of this study was to establish a method for the determination of these four kinds of ethanol's non-oxidative metabolites in dried blood spots (DBS) by liquid chromatography tandem mass spectrometry (LC-MS/MS), and to evaluate their stability. In this method, 50 μL of human blood was spotted onto a filter paper for DBS analysis. Samples were extracted by methanol, reconstituted by 2-propanol, and injected into the LC-MS/MS system. Limits of detection were among 0.5–50 ng/mL, and deviations in accuracy and precision were all lower than 15% at three quality control levels. The stability of the four kinds of ethanol non-oxidative metabolites in DBS was investigated during a 90-day range under three temperatures, −20 °C, 4 °C, and 25 °C. EtG and EtS showed a high level of stability in DBS in the 90-day range, regardless of the temperature. FAEEs were unstable after three days. PEths showed stability within 15 days in postmortem DBS and 60 days in antemortem DBS, respectively, at all temperatures.

This work presents a novel development that exploits the concept of in-situ gas-separation together with a specific enzymatic colorimetric detection to produce a portable biosensor called “Blood Alcohol Micro-pad” for direct quantitation of ethanol in whole blood. The thin square device (25 mm × 25 mm × 1.8 mm) comprises two layers of patterned filter paper held together with a double-sided mounting tape with an 8-mm circular hole (the headspace). In operation, the reagent is deposited on one layer and covered with sticky tape. Then 8 μL of a blood sample is dispensed onto the opposite layer and covered with sticky tape. Diffusion of ethanol across the 1.6 mm narrow headspace permits selective detection of ethanol by the enzymatic reagents deposited on the opposite layer. This reagent zone contains alcohol oxidase, horseradish peroxidase and 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, as the chromogenic reagent. The color intensity, measured from the recorded digital image, resulting from the enzymatic assay of ethanol, correlates with the concentration of blood alcohol. The results obtained with spiked mice and sheep blood samples, using an external calibration in the range of 1–120 mg dL−1ethanol, gave recoveries of 93.2–104.4% (n = 12). The “Blood Alcohol Micro-pad” gave good precision with %RSD

Cytochrome P450 (CYP450), and in particular CYP3A4, is the most abundantly expressed CYP450 isozyme implicated in many drug-drug and medicinal plant-drug interactions. Therefore, incorporation of CYP3A4 enzyme screening at an early stage of drug discovery is preferable in order to avoid enzymatic interactions. Here we present for the first time a paper-based CYP3A4 immobilized sol-gel-derived a platform using resorufin benzyl ether as a fluorogenic enzyme substrate used to investigate enzyme activity. The fluorescence intensity of the product can be simply quantified by using a handheld digital microscope and an image analysis software. The limit of quantitation was 0.35 μM with good precision (RSDs 0.05), while offering simplicity and lower cost. Kinetic parameters of the immobilized CYP3A4 in sol-gel coated paper were calculated from the Lineweaver-Burk plot, including Michaelis constant (Km) and maximum velocity (Vmax), which were 2.71 ± 0.35 μM and 0.43 ± 0.05 μM/min, respectively. Moreover, a functional test of these devices was conducted by assessments of known CYP3A4 inhibitors (i.e. ketoconazole, itraconazole) and inducers (i.e. phenytoin, carbamazepine). To further demonstrate the broad range of uses, the devices were utilized to assay plant extracts i.e. Areca catechu seeds, Camellia sinensis leaves, Eclipta prostrata aerial part, providing results in good agreement with previous studies. Furthermore, the sol-gel immobilized enzyme stored at 4 °C can increase storage stability, offering the activity of 86.3 ± 0.4% after 3-weeks storage, equivalent to the activity of the free enzyme solution after 1-week storage. The developed paper-based devices offer versatility, portability and low-cost.

The production of cellulose nanofibers (CNF) usually consist of two different phases. First of all, lignocellulosic fibers need to be treated by means of either chemical, enzymatic or mechanical treatments. Then, in the second phase, the treated lignocellulosic fibers need to be submitted to mechanical fibrillation. This last treatment is usually critical in terms of energy consumption, as well as for providing the appropriate characteristics to the resulting CNF. In the present work, we have investigated the effect of fibrillating lignocellulosic nanofibers (LCNF) made from eucalyptus sawdust by means of high-pressure homogenization and grinding. The obtained results showed that, to achieve the same property level of LCNF, the grinder consumed 12.86 kWh/kg, while the homogenizer, 19.07 kWh/kg, bringing to the light the suitability of grinding for LCNF production. Overall, the present work shows the feasibility of using eucalyptus sawdust, which is a residue from the pulp and paper industry, as raw material for LCNF production, at the same time that brings to the light the relevance of the fibrillation equipment in terms of energy efficiency, approaching the production of LCNF to the industry.

A novel 3D paper-based microfluidic screen-printed electrode (SPE) composed of two layers was constructed by photolithography and screen-printing technology. Aldehyde functionalized hydrophilic zone of the counter and reference electrodes layer was prepared for glucose oxidase immobilization. Highly conductive Prussian blue deposited reduced graphene oxide-tetraethylene pentamine (rGO-TEPA/PB) modified paper working electrode layer can be used as an electrochemical sensitive membrane for quantitative detection of hydrogen peroxide (H2O2), which was the enzyme-catalyzed reaction product. Therefore, this 3D paper-based microfluidic electrochemical biosensor can be used for quantitative detection of glucose. Under optimum conditions, the proposed biosensor can be used for quantitative determination of glucose over a wide linear range of 0.1 mM∼25 mM with detection limit of 25 μM. Finally, the 3D paper-based microfluidic electrochemical biosensor was applied to determine glucose in human sweat and blood, and the obtained results were in good consistency with values measured by Roche's blood glucose meter. In addition, the proposed 3D paper-based electrochemical device showed good repeatability, stability, and anti-interference, which would be of great potential to monitor glucose in complex biological fluids.

Rising concern about the use of non-permitted colourants, in common food items such as dals and green vegetables sold in Indian markets, have led to a demand for low-cost point-of-use chemical analysis tools. Conventional food-analysis techniques involving tedious sample preparation protocols are not suited for in-field applications. Surface Enhanced Raman Spectroscopy (SERS) is an analytical technique that is well-suited for point-of-use chemical analysis with molecular level detection capability, which can also serve as a quality assurance tool for businesses. Effective and rapid signal collection from a large-area sample within a field-setting using disposable, low-cost SERS substrates is a key challenge in implementing such a solution. Herein, we demonstrate the use of inkjet-printed thin films comprising of robust nanostructured-silver as flexible, paper-based SERS (P-SERS) swabs for the direct detection of Metanil Yellow (MY) from toor dal (yellow split pigeon peas) samples and Malachite Green (MG) from green peas and green chillies. The macroscopic uniformity of these thin-films in combination with a portable Raman spectrometer equipped with orbital raster scanning (ORS™) technology for signal collection results in an unprecedented precision (RSD ∼ 1.6%) upon characterizing samples saturated with Rhodamine-6G (R6G), a standard Raman probe. As several food-cleansing products have appeared in the marketplace, the adulterant removal efficacy of some commercially available ‘washes’ as well as products such as ‘ozoniser’, which was determined by SERS characterization of swabs before and after use, is also reported.

A novel all-in-one paper-based sampling concept for mass spectrometric bottom-up protein analysis is here demonstrated in a chip format integrating instant immunocapture, protein reduction, - alkylation and tryptic digestion all in-device. Conventional laboratory grade filter paper was coated with the polymer 2-hydroxyethyl methacrylate-co-2-vinyl-4,4-dimethyl azlactone (pHEMA-VDM) with a subsequent covalent immobilization of the monoclonal antibody E27 targeting the biomarker human chorionic gonadotropin (hCG). In-device protein reduction and alkylation was optimized with regards to reagent concentration and reaction pH. The sampling concept showed a high degree of performance between 10 and 1000 ng/mL (R2 > 0.99) by a five-point calibration curve sampled with hCG spiked to human serum samples and freshly collected whole blood samples, respectively. LOD (experimentally obtained at 100 pg/mL (2.64 pM/0.9 IU/L)) was demonstrated to be up to ten times lower with more than six times faster sample preparation than what has previously been reported for on-paper analysis of hCG in human serum samples.

The current work describes the development of a "nanopaper-based analytical device (NAD)", through the embedding of curcumin in transparent bacterial cellulose (BC) nanopaper, as a colorimetric assay kit for monitoring of iron and deferoxamine (DFO) as iron-chelating drug in biological fluids such as serum blood, urine and saliva. The iron sensing strategy using the developed assay kit is based on the decrease of the absorbance/color intensity of curcumin-embedded in BC nanopaper (CEBC) in the presence of Fe(III), due to the formation of Fe(III)-curcumin complex. On the other hand, releasing of Fe(III) from Fe(III)-CEBC upon addition of DFO as an iron-chelating drug, due to the high affinity of this drug to Fe(III) in competition with curcumin, which leads to recovery of the decreased absorption/color intensity of Fe(III)-CEBC, is utilized for selective colorimetric monitoring of this drug. The absorption/color changes of the fabricated assay kit as output signal can be monitored by smartphone camera or by using a spectrophotometer. The results of our developed sensor agreed well with the results from a clinical reference method for determination of Fe(III) concentration in human serum blood samples, which revealed the clinical applicability of our developed assay kit. Taken together, regarding the advantageous features of the developed sensor as an easy-to-use, non-toxic, disposable, cost-effective and portable assay kit, along with those of smartphone-based sensing, it is anticipated that this sensing bioplatform, which we name lab-on-nanopaper, will find utility for sensitive, selective and easy diagnosis of iron-related diseases (iron deficiency and iron overload) and therapeutic drug monitoring (TDM) of iron-chelating drugs in clinical analysis as well.

Driven by a bright prospect for rapid, portable and cost-effective point-of-care testing, an assembled Pasteur pipette device to integrate nucleic acid extraction, amplification and detection was developed to detect B. cereus in a sample-to-answer format. Denaturation Bubble-mediated Strand Exchange Amplification (SEA) was chosen to perform isothermal amplification because it requires only a pair of primers and one Bst DNA polymerase. The established SEA can detect as low as 1.0 × 10−13 M genomic DNA of B. cereus, which was comparable with the previously reported method for B. cereus detection. The assembled Pasteur pipette allows sample-to-answer diagnostic in a simple, low-cost, portable, and disposable format. The inherent function of Pasteur pipette enables direct liquid handling without the need of extra pipettes, syringes or pumps. Visual readout was achieved by using a pH sensitive dye, further simplifying result judgment process. The detection limit for B. cereus is 1.0 × 104 CFU/mL in pure cultures, while the detection limit in artificially contaminated milk is 1.0 × 105 CFU/mL without enrichment and 1.0 × 100 CFU/mL following 12 h enrichment. Considering that typical cell counts in food samples associated to food poisoning are 1.0 × 105 to 1.0 × 108 CFU per gram/milliliter B. cereus, our Pasteur pipette is enough sensitive for answer-to-sample diagnosis of B. cereus even directly from foods without enrichment. The whole diagnostic procedure could be completed within 50 min, dramatically decreasing the detection time. In a word, the assembled Pasteur pipette device, combined with a homemade metal bath, possesses great potential for sample-to-answer application in resource-limited settings.

Field-amplified stacking (FAS) is a commonly used method for enhancing the sensitivity of charged species from low conductive media in capillary electrophoresis. FAS also showed significant sensitivity enhancement effect on a uniform paper fluidic channel by proper design of the electrolyte. In this paper, a novel method of introducing electric field gradient is proposed by geometry design of a 2D paper fluidic channel, and field amplification effect was successfully demonstrated with reduced requirement on the sample's conductivity. Sensitive colorimetric detection of microalbuminuria (MAU) from urine samples was demonstrated by mobile phone camera. Experimental results showed that, with active electric field motivation, up to 93.5% of the loaded protein probe could be effectively transferred and stacked into a narrow band on the newly designed paper fluidic channel. A limit of detection (LOD) of 6.5 mg‧L−1 HSA was achieved with a dynamic range of 10–300 mg‧L−1 (linear in the range of 10–100 mg‧L−1, R2 = 0.991). Combined with selective staining of albumin with bromophenol blue (BPB), the established method was applied to the detection of MAU from clinical urine samples, and consistent results with that of the clinical method were obtained. With this paper-based analytical device (PAD), MAU from highly conductive urine samples can be directly loaded and detected without any pretreatment. This method provides a way to develop highly sensitive point-of-care test (POCT) for rapid screening of some diseases.

The adulteration of herbal medicines by dexamethasone or prednisolone is regarded as a serious problem in many communities. Herein, a novel platform for the separation and quantification of both target steroids in herbal medicines based on electrochemical paper-based analytical devices (ePADs) has been created. The ePAD was composed of Whatman SG81 chromatography paper, 3D-printed devices and a commercial screen-printed electrode. Whatman SG81 silica-coated paper was used for the separation of dexamethasone and prednisolone based on the difference in their partition coefficients during the flow of the mobile phase. The optimal mobile phase was composed of 60% ethyl acetate in cyclohexane and required 7 min for separation. The separated steroids on the paper were then quantified by electrochemical detection using differential pulse voltammetry, in which the 3D-printed devices facilitated the measurement. Analytical detection ranges of 10–500 μg mL−1 were obtained for both dexamethasone and prednisolone (r2 = 0.988 and 0.994, respectively). The limits of detection for dexamethasone and prednisolone were 3.59 and 11.98 μg mL−1, respectively, whereas the limits of quantification were 6.00 and 20.02 μg mL−1, respectively. The amounts of both target steroids derived from real herbal medicine samples determined by the proposed method were comparable to those obtained with assays using standard high-performance liquid chromatography. In addition, a simple evaporation step can be used to increase the concentration of the samples before analysis. These ePADs are simple, low-cost, rapid, and very promising for on-site quantitative detection.

In situ identification and quantification of unsaturated fatty acid (FA) C=C positional isomers in human serum is herein performed by negative-ion paper spray (PS) mass spectrometry. Typically, by direct application of an alternating current (AC) voltage to the wet paper, the PS ionization could perform stably in the negative-ion mode without severe discharge. We suppose epoxidation reaction between unsaturated C=C bonds and reactive oxidative species might be initiated by a mild electrical discharge, which could be rapidly and controllably produced via a low amplitude AC voltage. Upon collision-induce dissociation (CID), the epoxide was fragmented to generate diagnostic ions indicating the C=C location. The intensity of the characteristic product ions could also be used for absolute quantification of the FA C=C positional isomers. The limits of detection (LODs) and limits of quantification (LOQs) were roughly in the range of 0.0178–0.0506 μM and 0.0218–0.3634 μM for standard FAs. Without the additional sample preparations or reactive chemical reagents, epoxidation of unsaturated FAs and ionization of the epoxide could be achieved in one-step by negative-ion mode PS, which enable a promising methodology for on-site clinical diagnosis.

The present study delineates the preparation, characterization, and application of (3-Aminopropyl)triethoxysilane (APTES)/Caprine liver-derived extracellular matrix (CLECM) coated paper matrix for cell delivery. Here, we exploited positively charged surface of the paper matrix (as imparted by APTES derivatization) to improve the biological responses of the cells. Our results demonstrated that the functionalized paper matrixes favored the adhesion, growth, and proliferation of multiple cell types including normal, transformed, cancerous, and stem cells as compared to the pristine paper matrix. Upon implantation into the mice model, the developed paper matrix supported infiltration of the host cells and vasculature without showing any evidence of significant systemic toxicity. Moreover, the cells cultured on the paper matrix, when delivered to the CAM and mouse models, showed an enhanced vascular network around the substrate, thereby confirming its potential to deliver the cells in vivo. Together, the study confirms that the reported paper-based platform is easy to fabricate, cheap, portable and could efficiently be applied to cell delivery applications for either tissue repair or the development of humanized animal model.

A simple paper-based analytical device (PAD) has been developed to rapidly detect formaldehyde (FA) in food samples. The analysis was based on sulfite assay where FA reacted with excess sulfite to generate sodium hydroxide (NaOH) that was quantified on PAD using acid-base titration. The PAD consisted of a central sample zone connected to ten reaction and detection zones. All detection zones were pre-deposited with polyethylene glycol (PEG) with phenolphthalein (Phph) as an indicator. Reaction zones contained different amounts of the titrant, potassium hydrogen phthalate (KHP). On flowing into reaction zones, the NaOH product reacts with KHP to reach the end point. In the presence of excess NaOH, unneutralized NaOH reached the detection zone and caused Phph color change from colorless to pink. In contrast, when NaOH was less than KHP, the detection zone remained colorless. Concentration of FA can be quantified from the number of pink detection zone(s) which were correlated with a known amount of pre-deposited KHP on the PAD. Total analytical process could be completed within 5 min. Areas of each zone and amounts of reagents added to the corresponding zones of the PAD were optimized to obtain reproducible and accurate results. PAD gave ranges of FA detection of 100–1000 mg L−1 with an interval of 100 mg L−1 and the limit of detection (LOD) was 100 mg L−1. PADs were stable for up to a month under dark and cold conditions. Analysis of FA in food samples using PAD agreed well with those from the classical sulfite assay.

Fluoro-functionalized paper was prepared and applied in solid phase extraction (SPE) for the analysis of trace-level perfluorinated compounds (PFCs). The proposed fluoro-functionalized paper-based solid-phase extraction (Fp-SPE) exhibits significant advantages for sample preparation, such as the biodegradability of paper-based adsorbent, simple manipulation and low cost. Owing to the fluorous affinity, the Fp-SPE technique with high sensitivity and high selectivity is more suitable for the selective enrichment of fluorine-containing molecules from the background of non-fluorinated organic compounds in a real water sample. Combined with high-performance liquid chromatography coupled with electrospray ionization-tandem mass spectrometry analysis (HPLC-MS/MS), the linear range of the PFCs, including perfluorobutyric acid (PFBA), perfluorooctanic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorodecanoic acid (PFDA), was 0.20–5.0 ng/L with the limits of detection (LOD) ranging from 0.04–0.05 ng/L and the limits of quantification (LOQ) ranging from 0.15-0.20 ng/L. The method was then applied to the analysis of tap water, river water and waste water samples. The results of the actual sample analysis are consistent with that by reverse phase SPE (RP-SPE).

In most cases, three-dimensional paper-based microfluidic analytical devices (3D-μPADs) were fabricated manually by stacking or folding methods. For the first time, digital light processing stereolithography (DLP-SLA) 3D printing technology was adopted to automatically make 3D-μPADs. In the fabrication process, a printing pause was set between two layers to allow paper to be placed in the resin tank. The resin on the fresh paper spontaneously bonded to the former cured paper layer during curing, thus realizing the automatic bonding and alignment between different layers of paper and avoiding the human participation and errors as in stacking and folding methods. There was a gap between two vertical aligned flow paths, therefore the liquid did not flow spontaneously from the upper layer to the lower layer. Most of the fluid flow in 3D-μPADs was spontaneous or manually activated, which was not conducive to complex assays that require different regents to be delivered sequentially. Herein, we used an electric field or airflow to trigger the fluid flow and demonstrated the flow controllability by a proof-of-concept colorimetric assay. The limits of detection of glucose and albumin were 0.8 mM and 3.5 μM, respectively, which were sufficient for clinical requirements. Given the characteristic of flow controllability, we believe that the proposed 3D-μPADs have great potential to make paper-based complex assays automated and programmable.

A new highly selective and sensitive dual-mode sensor 3TD based on the conjugate of oligothiophene and barbituric acid moiety was developed for colorimetric and turn-on fluorescent detection of CN─. The sensor 3TD exhibited high specificity towards CN─ by interrupting its own ICT producing thereupon a large blue-shift in UV–Vis spectrum and remarkable “turn-on” fluorescence emission. The detection limit was 2.26 × 10─7 M, which is quite lower than the permissible level of CN─ in drinking water according to the WHO. The fluorescent detection of CN─ was well demonstrated by filter paper strips and silica coated TLC plates. Moreover, the sensor was also used to detect CN─ in environmental water and agro-products with satisfactory results. Most importantly, in terms of these advantages of colorimetric and turn-on fluorescent dual-mode, immediate response, excellent selectivity, high sensitivity, low cytotoxicity, and good biocompatibility, the sensor 3TD was successfully applied into CN− imaging in living cells, demonstrating its excellent value in practical application.

Chloride (Cl-) is an inorganic anion present in a broad range of samples (e.g. biological, environmental, food, water, etc.), the determination of which is of widespread significance. In this work, we translate the well-established traditional argentometric method (Mohr's precipitation titration) into a small, simple, portable, and low-cost paper-based microfluidic diagnostic device, which provides rapid and quantitative analysis. The developed device enables the determination of chloride sample volumes as small as 5 μL. A distance-based detection method is implemented providing fully instrument-free quantitation. The beneficial effects of channel geometry (variable widths with constant heights) on analytical parameters were investigated. Trapezoidal channels (channel width changes linearly with height) were used to create a gradient of paper surface (titrant) available for the reaction, compared to the typical uniform rectangular channels (constant channel width). The trapezoid with increasing width offered higher sensitivity and lower detection limits (i.e. 0.05 mM vs 0.1 mM from the rectangular channel) for chloride determination across the concentration range of 0.05-25 mM. In addition, the effect of concentration of the deposited reagent on the obtained distance signals was investigated using varying concentrations of titrant (AgNO3), which allowed determination of chloride across a wider dynamic range (up to 200 mM). The utility of the paper devices was demonstrated by determination of chloride in a variety of matrices including body fluids (sweat, serum, and urine) and water samples (drinking, mineral, river water).

The facile detection of phosphopeptides is important for clinical screening and phosphoproteomic research. This work develops an instrument-free, cost-effective, convenient paper-based method for quantitative analysis of phosphorylated peptides. With a novel portable device, Phos-PAD, this method can achieve selective enrichment and colorimetric detection of phosphopeptides within 15 min TiO2 nanoparticle-based chemisorption and tetrabromophenol blue-based colorimetric assay were integrated into the single paper-based analytical device. The color change can indicate the presence of phosphopeptides and the mean pixel intensity of the red channel can be used for phosphopeptide quantification. With capability of quantifying phosphopeptides in serum samples, this Phos-PAD assisted phosphopeptide assay may attract significant attention to clinical analysis of endogenous serum phosphopeptides.

The adsorption of hydrocarbons present in gasoline residues on household materials was investigated via inverse gas chromatography (IGC). A series of hydrocarbons (n-heptane, n-octane, n-nonane, toluene, p-xylene, and 1,2,4-trimethylbenzene) and three household materials (carpet fibers, cotton fabric, and cardboard) were selected in this work. IGC measurements using columns packed with these household materials were conducted to obtain molar enthalpies of adsorption of the selected hydrocarbons over the temperature range of 40 to 70 °C. Adsorption isotherms and Henry’s law solubility coefficients (S) were also determined at 40 °C. Results from our IGC measurements revealed that molar enthalpies of adsorption, adsorption isotherms, and solubility coefficients were largely dependent upon the structures and size of hydrocarbons and the choice of solid substrates. Measured molar enthalpies of adsorption became more exothermic with increasing size of hydrocarbons, ranging from −23.4 to −40.9 kJ/mol for carpet fibers, −36.2 to −48.2 kJ/mol for cotton fabric, and −30.1 to −52.5 kJ/mol for cardboard. From the adsorption isotherms and the measured retention times as a function of the injection amount, the adsorption affinity of hydrocarbons to the carpet fibers was found to be weaker than the affinity between hydrocarbon molecules, producing relatively lower solubility coefficients for all hydrocarbons than those measured on cotton fabric and cardboard. However, the adsorption affinities of hydrocarbons to both cotton fabric and cardboard were much stronger with increased solubility coefficients presumably due to the diffusion and dispersion of hydrocarbons through solid substrates. In particular, solubility coefficients of three aromatics on cardboard were significantly larger than those measured on carpet fibers and cotton fabric. This might be responsible for previously reported enhanced persistence of gasoline residues spiked on cardboard.

This paper describes the development of two microfluidic paper-based analytical devices (μPADs), one well-based and the other based on a lateral flow assay (LFA) configuration, to detect glucose via a colorimetric assay using the solid metal-organic framework (MOF) Zr-PCN-222(Fe), to encapsulate glucose oxidase (GOx). The well-based platform consisted of laminate sheets and multiple layers of wax-printed chromatography paper. Solutions of KI and glucose placed into the well flowed through the device and reacted with the GOx@MOF species sandwiched between the paper layers realizing a yellow-brown color. The LFA platform consisted of chromatography paper between parafilm and polyvinyl acetate (PVA) layers. GOx@MOFs spotted on the paper subjected to solutions of KI and glucose yielded a brown color. The devices were then dried, scanned, and analyzed yielding a correlation between average inverse yellow intensity and glucose concentrations. The development of these devices employing MOFs as biomimetic catalysts should further expand the applications of microfluidic technologies for sensors a variety of analytes.

Metagenomics has emerged to isolate novel enzymes from the uncultured microbiota in the environment. In this study, the metagenomic data obtained from camel rumen was considered as the potential source of microbial xylanase enzymes with proper activity in extreme conditions. The metagenomic data were assembled and contigs were used for in-silico identification of candidate thermostable enzyme. A novel thermostable xylanase enzyme, named PersiXyn1, with 1146 bp full-length gene which encodes a 381 amino acid protein was identified. Using the DNA template extracted from camel rumen metagenomic samples, the candidate enzyme genes were cloned and expressed in proper E. coli strains. The phylogenetic analysis showed the evolutionary position of PersiXyn1 among the known thermostable xylanases. The results of the CD analysis and determining the secondary structure of the enzyme, confirmed the presence of a high percentage of β-sheets as an important characteristic of thermophilic xylanases. The PersiXyn1 was active at a broad range of pH (6–11) and temperature (25–90 °C). The optimum pH and temperature were 8 and 40 °C respectively, and the enzyme maintained 80% of its maximum activity in the pH 8 and temperature 40 °C for 1 h. The Scanning electron microscope (SEM) micrograph of enzyme treated pulp clearly showed that the effective use of enzymes in fiber separation may reduce the cost of carton paper production. The novelty of this enzyme lies in the fact that it is highly active and stable in a broad range of pH and temperature. This study highlights the potential importance of camel microbiome for discovering novel thermostable enzymes with applications in agriculture and industries.

In this research, collagen hydrolysates with different average molecular weights ( Mn ¯ ) from leather collagen were chosen as raw materials. Five environmental-friendly sizing agents (SA) were prepared by cross-linking collagen hydrolysates with glycol diglycidyl ether (GDE) and further grafting them with butyl acrylate (BA) and styrene (St). Then the compound sizing agents (SGDESA-x, x = 1, 2, 3 and 4) were obtained by simple physical mixing of GDESA and starch. The surface sizing performance of GDESA and compound sizing agents were studied. The research result shows that both physical, mechanical properties and water resistance of the corrugated paper coated by GDESA were significantly improved when Mn ¯ of collagen hydrolysate was about 10,000, and its emulsion exhibited robust stability in long standing time. Furthermore, when the SGDESA-2 was used as a sizing agent, the coated corrugated paper exhibited strong water resistance, good physical and mechanical properties even after refolded for 20 times.

This work demonstrates a sensitive and rapid method for the detection of antibiotic residues in food samples by employing the filtration behaviour of paper combined with aggregation and precipitation of chemical reagents. Using this concept, we successfully determined the presence of oxytetracycline and norfloxacin residues in pork using metal complexation on microfluidic paper-based analytical devices (μPADs). The base substrate (top layer of the device) was fabricated by printing letter channels of the words “oxytetracycline” and “norfloxacin” before functionalization with copper (II) sulfate pentahydrate in 0.5 M sodium hydroxide and iron (III) nitrate nanohydrate in 5 mM ammonia solution for the detection of oxytetracycline and norfloxacin separately. A transition metal hydroxide formed upon reaction that created solid precipitates on paper and allowed antibiotic residues to bind to the metal ions via coordination chemistry. The metal ion-antibiotic complex could form on the filter paper and generated a visible color change with the detection limit of 1 ppm for both oxytetracycline and norfloxacin in pork. This procedure of filtration and concentration in combination with a simple text-reporting approach allows the end users to achieve a low limit of detection as well as easy result interpretation in food safety monitoring. usc Refereed/Peer-reviewed

Herein, the applicability of electromembrane extraction (EME), as an efficient and paper-compatible separation technique, was envisaged over customized microfluidic paper-based analytical devices (μPADs). The utility of EME was assessed on 2D planar and 3D origami structures using different types of electrodes including stainless steel and paper-based electrodes. The overall separation procedure was integrated to colorimetric detection demonstrated for copper ions as the model analyte. According to the obtained results, EME based on 3D design of μPADs could effectively be performed under low applied voltage. Using 3D architecture, the analyte could be quantified within the range of 40.0-1500.0 μg L

In this paper, simultaneous enrichment and separation of ions and amphoteric components were successfully demonstrated by using electric field (E) and pH gradient (double gradient) in the ion depletion zone of anion concentration polarization interface established on a paper fluid channel. Experimental results were visualized with colored ions (bright blue and amaranth) and protein probes (phycocyanin and cytochrome C). With optimization, colored phycocyanin and bovine hemoglobin with similar pI as that of albumin and immunoglobulin respectively were well separated in 900 s with 10-fold enrichment effect. Based on the separation and enrichment function of this paper-based analytical device (PAD) and rapid selective staining of human serum albumin (HSA) with bromophenol blue, a rapid colorimetric detection of HSA was implemented with smartphone camera. A limit of detection (LOD) of 5.2 mg·L

Identification of Cronobacter represent a major challenge for laboratories testing powdered infant formula (PIF). In the present study, two biochemical galleries and three molecular methods have been applied to confirm 276 Cronobacter spp. and non-Cronobacter isolates from different sources. Using the latest database of API 20 E and ID 32 E biochemical miniaturized kits, 53% and 78% of the isolates were identified respectively. From the available results, total accuracy for Cronobacter detection was in 97% (API 20 E) and 99% (ID 32 E). The three molecular methods were based on rRNA based lateral flow, Real Time PCR combined with either a hybridization or hydrolysis probe. For all three methods total accuracy was more than 99%. A pilot trial using Next Generation Sequencing (NGS) correctly identified 58 out of 66 isolates (88%) in DNA mixtures. The results indicate that the commercially available approaches such as ID 32 E, rRNA based lateral flow and Real Time PCR are all suitable for Cronobacter identification at the genus level. The NGS method may become a suitable alternative in the future, provided that the sequence database is improved.

Solar-reflective thermal insulating coating (SRC) has received great attention because of its desired heat reflective properties and water repellency, which may impart high-value to cellulosic paper via industrially well-established surface coating process. However, the feasibility and possibility of surface application of SRC to cellulosic paper have not been explored. Herein, in the present work, SRC was designed/developed and subsequently used in the surface application to cellulosic paper. Effect of feeding level of titanium dioxide nanoparticles (nano-TiO2) on rheological behavior of the coating, as well as heat-reflective properties, water repellency and mechanical properties of the surface-coated paper was studied. Results showed that the as-obtained coating samples exhibited a notable shear-thinning behavior and displayed strong dependence of rheological behavior on nano-TiO2 amount. Furthermore, the increased nano-TiO2 amount appeared to induce the improved hemispherical emittance of coated paper. The coating weight was also found to exert a positive effect on the hemispherical emittance of coated paper. In addition, it was confirmed that the nano-TiO2 addition played an important role in improving the water repellency and mechanical properties of coated paper.

This study describes the development of paper-based devices for the determination of biothiols. The devices are inexpensive (composed of paper and silver halide particles), and the analytical protocol is easily executable with minimum technical expertise and without the need of specialized equipment; the user has to add a test sample, illuminate the device with a UV lamp, and read the color change of the sensing area using a simple imaging device (i.e., cell-phone camera) or a bare eye. The detection mechanism of the assay is based on the biothiols-mediated photoreduction of nanometer-sized silver chloride particles deposited on the surface of paper; photoreduced silver chloride particles have a grayish coloration that depends on the concentration of biothiols in the tested solution. This is the first time that the UV-mediated photoreduction of solid silver halides particles is used for analytical purposes. The performance of the devices has been tested on the detection of total biothiols content of artificial body fluids and protein–free human blood plasma samples, and the results were satisfactory in terms of sensitivity, selectivity, recoveries and reproducibility.

In this study, a slug-flow microextraction (SFME) coupled with paper spray mass spectrometry (PS-MS) method was developed for rapid and on-site analysis of trace amphetamine-type illicit drugs including amphetamine (AM), methamphetamine (MA) and 3,4-methylenedioxy-N-methylamphetamine (MDMA) in complex biological samples such as whole blood and raw urine. The method involved the application of SFME for rapid extraction of trace amphetamine-type illicit drugs from whole blood and raw urine samples, followed by PS for direct MS analysis under ambient and open-air conditions. The experimental parameters including extraction solvent, extraction cycle, high voltage, and spray solvent, etc., were all investigated, and the optimized conditions showed an enhanced sensitivity of 1–2 order of magnitudes compared with PS-MS. The method showed good linearity, with correlation coefficient values (r) of no less than 0.9979 for analysis of AM, MA, and MDMA in human whole blood and raw urine without additional sample pretreatments. The limits of detection and quantification were 0.01–0.05 ng/mL and 0.05–0.2 ng/mL, respectively. Satisfactory recoveries were also obtained, with 74.2–94.9% for whole blood and 80.2–103.6% for raw urine, respectively. All of our experimental results demonstrated that SFME-PS-MS showed great potential for rapid, on-site, in situ, and high-throughput screening of amphetamine-type illicit drugs in various biological samples.

Halophilic microorganisms have great potentials towards biotechnological applications. Halomonas hydrothermalis Y2 is a halotolerant and alkaliphilic strain that isolated from the Na+-rich pulp mill wastewater. The strain is dominant in the bacterial community of pulp mill wastewater and exhibits metabolic diversity in utilizing various substrates. Here we present the genome sequence of this strain, which comprises a circular chromosome 3,933,432 bp in size and a GC content of 60.2%. Diverse genes that encoding proteins for compatible solutes synthesis and transport were identified from the genome. With a complete pathway for ectoine synthesis, the strain could produce ectoine from monosodium glutamate and further partially secreted into the medium. In addition, around 20% ectoine was increased by deleting the ectoine hydroxylase (EctD). The genome sequence we report here will provide genetic information regarding adaptive mechanisms of strain Y2 to its harsh habitat, as well as facilitate exploration of metabolic strategies for diverse compatible solutes, e.g., ectoine production.

In this study, we have attempted to extract cellulose fiber from newspaper waste for circular economy project. Cellulose was successfully extracted from newspaper waste with high purity. It was further developed as a composite with Fe3O4 powder. 10–30 wt% of Fe3O4 was synthesized from conventional synthetic route and it was uniformly distributed into cellulose suspension. The composite was prepared by freeze-dry technique in order to remove water and create the porosity. X-ray diffraction and thermogravimetric analysis were employed to characterize the structural and thermal properties of composite. Scanning electron microscope with energy dispersion analysis can be confirmed that uniformity of cellulose and the existence of Fe3O4 powder. Frequency dependence of dielectric properties was used to imply the polarity enhancement of composite. Preliminary adsorption of composite as adsorbent material for Congo red was investigated.

Using waste paper as fuel for domestic heating is a beneficial recycling option for small island developing states where there are lacks of resources for energy and waste treatment. However, there are concerns about the impact of air pollutants emitted from the burning of the self-made paper briquettes as household air pollution is recognised as the greatest environmental risk for human. In this study, combustion tests were carried out for paper briquettes made in one Pacific island and three commercial fuels in Australia including wood briquettes, kindling firewood and coal briquettes in order to: 1) characterise the emissions of three criteria air pollutants including particulate matters, CO and NOx including their emission factors (EF) from the tested fuels; and 2) compare the EFs among the tested fuels and with others reported in the literature. The results showed that waste paper briquettes burned quickly and generated high temperature but the heat value is relatively low. Paper briquettes and coal briquettes produced higher CO concentration than the others while paper briquettes generated the highest NOx level. Only PM2.5 concentration emitted from paper briquettes was similar to kindling firewood and lower than wood briquettes. Burning of paper briquettes and wood briquettes produced particulate matter with large average count median diameter (72 and 68 nm) than coal briquette and kindling firewood (45 and 51 nm). The EFs for CO, NOx and PM2.5 of paper briquettes were within the range of EFs reported in this study as well as in the literature. Overall, the results suggested that using paper briquettes as fuel for domestic heating will not likely to generate higher level of three major air pollutants compared to other traditional fuels.

Driven by the environmental benefits that bio-bleaching could bring, the interest in xylanase has received enormous attention and hence, the search of xylanase with properties like no cellulase activity, function at elevated temperatures and pH continues. The present study reports the production of extracellular xylanase from Aspergillus nidulans using waste agro-residues as substrate. The optimum temperature (60 °C) and pH (9.0), classified the xylanase as thermo and alkali tolerant. The addition of salt of Mn2+ increased the xylanase activity to almost double; however, these ions were unable to protect the enzyme from thermal inactivation. The FTIR spectra of bamboo pulp treated with this xylanase, revealed reduction in lignin as evident from reduced peak intensity coupled with the reduction in kappa number. The SEM image of enzyme treated pulp, exhibited dissociation in fibers exposing the internal structure with slight roughness. Swelling was also observed there by increasing its thickness which eventually helped in improving its physical properties. The bleaching efficacy of indigenous xylanase as indicated in this study, has established its competence as a promising candidate for pre-treating the bamboo pulp.

The use of paper-based methods for clinical diagnostics is a rapidly expanding research topic attracting a great deal of interest. Some groups have attempted to realize an integrated nucleic acid test on a single microfluidic paper chip, including extraction, amplification, and readout functions. However, these studies were not able to overcome complex modification and fabrication requirements, long turn-around times, or the need for sophisticated equipment like pumps, thermal cyclers, or centrifuges. Here, we report an extremely simple paper-based test for the point-of-care diagnosis of rotavirus A, one of the most common pathogens that causes pediatric gastroenteritis. This paper-based test could perform nucleic acid extraction within 5 min, then took 25 min to amplify the target sequence, and the result was visible to the naked eye immediately afterward or quantitative by the UV–Vis absorbance. This low-cost method does not require extra equipment and is easy to use either in a lab or at the point-of-care. The detection limit for rotavirus A was found to be 1 × 103 copies/mL. In addition, 100% sensitivity and specificity were achieved when testing 48 clinical stool samples. In conclusion, the present paper-based test fulfills the main requirements for a point-of-care diagnostic tool, and has the potential to be applied to disease prevention, control, and precision diagnosis.