Search

The prevalence of diabetes has increased over the past years. Therefore, developing minimally invasive, user-friendly and cost-effective glucose biosensors is necessary especially in low-income and developing countries. Cellulose paper-based analytical devices have attracted the attention of many researchers due to affordability, not requiring trained personnel, and complex equipment. This paper describes a microfluidic paper-based analytical device for the detection of glucose in tear with the naked eye. The paper-based biosensor fabricated by laser CO2, and GOx/HRP enzymatic solution coupled with TMB was utilized as reagents. A sample volume of 10 µl was needed for the biosensor operation and the results were observable within 5 minutes. To evaluate the device performance, color intensity-based and distance-based results were analyzed by ImageJ and Tracker. Distance-based results showed a linear behavior in the range of 0.1–0.6 mM with an R2 = 0.967 and LOD of 0.2 mM. The results could be perceived by the naked eye without any need to further equipment or trained personnel in a relatively short time (3–5 minutes). Moreover, glucose concentration could be obtained non-invasively by tears collected by this µPAD.

The pulp and paper industry discharges massive amount of wastewater containing hazardous organochlorine compounds released during different processing stages. Therefore, some cost-effective and nonpolluting practices such as enzymatic treatments are required for the potential mitigation of effluents released in the environment. Various xylanolytic enzymes such as xylanases, laccases, cellulases and hemicellulases are used to hydrolyse raw materials in the paper manufacturing industry. These enzymes are used either individually or in combination, which has the efficient potential to be considered for bio-deinking and bio-bleaching components. They are highly dynamic, renewable, and high in specificity for enhancing paper quality. The xylanase act on the xylan and cellulases act on the cellulose fibers, and thus increase the bleaching efficacy of paper. Similarly, hemicellulase enzyme like endo-xylanases, arabinofuranosidase and β-d-xylosidases have been described as functional properties towards the biodegradation of biomass. In contrast, laccase enzymes act as multi-copper oxidoreductases, bleaching the paper by the oxidation and reduction process. Laccases possess low redox potential compared to other enzymes, which need some redox mediators to catalyze. The enzymatic process can be affected by various factors such as pH, temperature, metal ions, incubation periods, etc. These factors can either increase or decrease the efficiency of the enzymes. This review draws attention to the xylanolytic enzyme-based advanced technologies for pulp bleaching in the paper industry.

The outbreak of new viral strains promotes advances in universal diagnostic techniques for detecting infectious diseases with unknown viral sequence. Long double-stranded RNA (dsRNA), a hallmark of infections, serves as a virus marker for prompt detection of viruses with unknown genomes. Here, we report on-chip paper electrophoresis for ultrafast screening of infectious diseases. Negatively charged RNAs pass through the micro and nanoscale pores of cellulose in order of size under an external electric field applied to the paper microfluidic channel. Quantitative separation of long dsRNA mimicking poly I:C was analyzed from 1.67 to 33 ng·μL−1, which is close to the viral dsRNA concentration in infected cells. This paper-based capillary electrophoresis chip (paper CE chip) can provide a new diagnostic platform for ultrafast viral disease detection at the point-of-care (POC) level.

The salivary glands are closely associated with stress conditions and the neuroendocrine system. The concentrations of these salivary biomarkers fluctuate with a person’s disease status. Until now, salivary diagnostics have been promising; however, the analytical tools for detecting salivary biomarkers have remained burdensome due to the lack of user-friendly and cost-effective equipment. In this study, we used a microfluidic starch-coated paper-based chip to isolate ɑ-amylase from human saliva. The concentration of ɑ-amylase on the head and tail sections of the paper-based chip was compared in the presence or absence of starch. We found that ɑ-amylase was highly concentrated only in the head section of the starch-coated paper-based chip through Western blotting (WB) and enzyme-linked immunosorbent assay (ELISA). We expect our designed paper-based chip will aid in α-amylase detection technologies using saliva and small amounts of other biofluids including blood, tears, pancreatic juice, and urine.

Due to their unique properties, paper-based biosensors have attracted attention as inexpensive devices for on-site analysis. To achieve fast and sensitive detection of analytes, immobilization of enzymes with high apparent activities on paper is highly desirable; however, this is challenging. Herein, we report an improved approach to attach a malathion degrading enzyme, PoOPHM9, on paper via an interlocking network of Pluronic F127 (PF127)–poly(acrylic acid)–enzyme conjugates. The addition of PF127 improved retention of enzymatic activity as the apparent kinetic constant Vmax of the immobilized enzyme increased two-fold compared with the paper prepared without PF127. The PF127–poly(acrylic acid)–PoOPHM9 papers provided rapid colorimetric detection of malathion at 0.1–50 mM. The detection was completed within 5 min using a smartphone and image analysis software. As a proof-of-concept, malathion-contaminated water, plant, and apple samples were analyzed with the papers successfully. This material is promising for on-site rapid analysis of malathion-contaminated samples.

The pulp and paper industry is a major source of lignocellulose-containing streams. The components of lignocellulose material are lignin, hemicellulose, and cellulose that may be hydrolyzed into their smaller components and used as feedstocks for valorization efforts. Much of this material is contained in underutilized streams and waste products, such as black liquor, pulp and paper sludge, and wastewater. Bacterial fermentation strategies have suitable potential to upgrade lignocellulosic biomass contained in these streams to value-added chemicals. Bacterial conversion allows for a sustainable and economically feasible approach to valorizing these streams, which can bolster and expand applications of the pulp and paper industry. This review discusses the composition of pulp and paper streams, bacterial isolates from process streams that can be used for lignocellulose biotransformations, and technological approaches for improving valorization efforts. KEY POINTS: • Reviews the conversion of pulp and paper industry waste by bacterial isolates. • Metabolic pathways for the breakdown of lignocellulose components. • Methods for isolating bacteria, determining value-added products, and increasing product yields.

Magnetic Resonance Imaging linear-accelerator (MRI-linac) equipment has recently been introduced to multiple centres in Australia and New Zealand. MRI equipment creates hazards for staff, patients and others in the MR environment; these hazards must be well understood, and risks managed by a system of environmental controls, written procedures and a trained workforce. While MRI-linac hazards are similar to the diagnostic paradigm, the equipment, workforce and environment are sufficiently different that additional safety guidance is warranted. In 2019 the Australasian College of Physical Scientists and Engineers in Medicine (ACPSEM) formed the Magnetic Resonance Imaging Linear-Accelerator Working Group (MRILWG) to support the safe clinical introduction and optimal use of MR-guided radiation therapy treatment units. This Position Paper is intended to provide safety guidance and education for Medical Physicists and others planning for and working with MRI-linac technology. This document summarises MRI-linac hazards and describes particular effects which arise from the combination of strong magnetic fields with an external radiation treatment beam. This document also provides guidance on safety governance and training, and recommends a system of hazard management tailored to the MRI-linac environment, ancillary equipment, and workforce.

An industry compatible chemo-refining approach was tested for preparation of micro-nanofibrillated cellulose (MNFC) from bleached softwood pulp using sodium meta-periodate and sodium chlorite as oxidizers followed by refining in Valley beater. SEM and FTIR analyses confirmed micro-nano scale fibrillation and chemical functional group modification in laboratory prepared MNFC, respectively. The water retention value, carboxyl content and viscosity of MNFC were found comparable with imported NFC as reference (R-NFC). To evaluate MNFC as strength enhancer for paper properties, 5% MNFC addition to bleached mixed hardwood pulp showed 6% reduction in bulk with 36%, 24% and 97% increment in breaking length, burst index and double fold of the handsheets, respectively without affecting tear index and optical properties than the control. Surface properties were also improved. Pulp drainability (37°SR) after MNFC addition was found suitable for papermaking. These laboratory results confirmed the potential of MNFC as a suitable strength additive for paper quality improvement.

Consistency and clear guidelines on dosimetry are essential for accurate and precise dosimetry, to ensure the best patient outcomes and to allow direct dose comparison across different centres. Magnetic Resonance Imaging Linac (MRI-linac) systems have recently been introduced to Australasian clinics. This report provides recommendations on reference dosimetry measurements for MRI-linacs on behalf of the Australiasian College of Physical Scientists and Engineers in Medicine (ACPSEM) MRI-linac working group. There are two configurations considered for MRI-linacs, perpendicular and parallel, referring to the relative direction of the magnetic field and radiation beam, with different impacts on dose deposition in a medium. These recommendations focus on ion chambers which are most commonly used in the clinic for reference dosimetry. Water phantoms must be MR safe or conditional and practical limitations on phantom set-up must be considered. Solid phantoms are not advised for reference dosimetry. For reference dosimetry, IAEA TRS-398 recommendations cannot be followed completely due to physical differences between conventional linac and MRI-linac systems. Manufacturers’ advice on reference conditions should be followed. Beam quality specification of TPR20,10 is recommended. The configuration of the central axis of the ion chamber relative to the magnetic field and radiation beam impacts the chamber response and must be considered carefully. Recommended corrections to delivered dose are $${k}_{{Q}_{msr}{Q}_{0}}^{{f}_{msr}{f}_{ref}}$$ k Q msr Q 0 f msr f ref , a correction for beam quality and $${k}_{\overrightarrow{B},{Q}_{msr}}^{{f}_{msr}}$$ k B → , Q msr f msr , for the impact of the magnetic field on dosimeter response in the magnetic field. Literature based values for $${k}_{\overrightarrow{B},{Q}_{msr}}^{{f}_{msr}}$$ k B → , Q msr f msr are given. It is important to note that this is a developing field and these recommendations should be used together with a review of current literature.

By way of broadening the use of diverse sustainable bioethanol feedstocks, the potentials of Paper mulberry fruit juice (PMFJ), as a non-food, sugar-based substrate, were evaluated for fuel ethanol production. The suitability of PMFJ was proven, as maximum ethanol concentration (56.4 g/L) and yield (0.39 g/g) were achieved within half a day of the start of fermentation, corresponding to very high ethanol productivity of 4.7 g/L/hr. The established potentials were further optimally maximized through the response surface methodology (RSM). At the optimal temperature of 30 °C, yeast concentration of 0.55 g/L, and pH of 5, ethanol concentration, productivity, and yield obtained were 73.69 g/L, 4.61 g/L/hr, and 0.48 g/g, respectively. Under these ideal conditions, diverse metal salts were afterward screened for their effects on PMFJ fermentation. Based on a two-level fractional factorial design, nutrient addition had no positive impact on ethanol production. Thus, under the optimal process conditions, and without any external nutrient supplementation, bioethanol from PMFJ compared favorably with typical sugar-based energy crops, highlighting its resourcefulness as a high-value biomass resource for fuel ethanol production. Graphical Abstract

A laminated paper-based analytical device (LPAD) for histidine detection was fabricated from a chromatography filtration paper and laminate films. Histidine recognition was effected by histidyl-tRNA synthetase (HisRS), and its detection was signaled colorimetrically based on the molybdenum blue reaction. The analytical conditions and detectable concentration range of histidine were examined. The method provided selective quantification from 1 to 100 μM histidine. LPAD fabrication is considerably simple, involving only the craft-cutting of the chromatography filtration paper and laminate film, and is cost-effective.

Directed evolution has become an important method to unleash the latent potential of enzymes to make them uniquely suited for human purposes. However, the need for a large reagent volume and sophisticated instrumentation hampers its broad implementation. In an attempt to address this problem, here we report a paper-based high-throughput screening approach that should find broad application in generating desired enzymes. As an example case, the dehalogenation reaction of the halohydrin dehalogenase was adopted for assay development. In addition to visual detection, quantitative measurements were performed by measuring the color intensity of an image that was photographed by a smartphone and processed using ImageJ free software. The proposed method was first validated using a gold standard method and then applied to mutagenesis library screening with reduced consumption of reagents (i.e., ≤ 10 μl per assay) and a shorter assay time. We identified two active mutants (P135A and G137A) with improved activities toward four tested substrates. The assay not only consumes less reagents but also eliminates the need for expensive instrumentation. The proposed method demonstrates the potential of paper-based whole-cell screening coupled with digital image colorimetry as a promising approach for the discovery of industrially important enzymes.Key Points• A frugal method was developed for directed enzyme evolution.• Mutagenesis libraries were successfully screened on a paper platform.• Smartphone imaging was efficiently used to measure enzyme activities.

The study describes the preparation of pulp and nanocellulose from non-wood plant materials, as well as an improved properties of paper and cardboard for mass production. The pulps from wheat straw, kenaf and flax fibers were prepared by the environmentally friendly organosolv method—cooking in a solution of isobutanol or peracetic acid. The organosolv pulps used to prepare nanocellulose had traces of lignin and mineral substances. The process of hydrolysis of the investigated organosolv pulps was optimal when carried out under the following conditions: 43% sulfuric acid, temperature 60 °C, hydrolysis time 90 min and ultrasonic treatment 60 min. Using the methods of SEM, XRD, TEM, AFM and TGA, the structure and properties of organosolv pulps and nanocellulose were studied. The use of nanocellulose in bulk and on the surface of mass types of paper and cardboard—paper for corrugation, offset paper, recycled containerboard and cardboard for flat layers of corrugated cardboard were investigated. We established the positive effect of nanocellulose application on the physical and mechanical properties of paper and cardboard. Low consumption of nanocellulose allows production of the paper and cardboard with properties that meet the requirements to appropriate standards and replacement of synthetic reinforcing materials.

The main objective of this study is the evaluation of RPPW anaerobic digestion feasibility at laboratory scale under Mesophilic condition. The experiment is conducted using a two-stage biofilm digester of 5 L capacity with mobile support material. Anaerobic treatment of wastewater from recycled pulp and paper industry in Morocco was tested using a laboratory-scale anaerobic biofilm digester that operated under mesophilic conditions over a 70-day. Chemical oxygen demand (COD) efficiency, volatile and total solid (VS, TS) elimination of the substrate during the process were: 78%, 52% and 48% respectively. The system was stable throughout its operating cycle with an optimum pH (7.24), alkalinity (1750 mg CaCO3/L) and a volatile fatty acid value (760 mg/L). The experimental daily biogas production measured reaches a value of 5 L/day with a composition of 71% methane, 27.6% carbon dioxide, 0.2 oxygen and 7713 ppm of the H2S. The study results show that the anaerobic biofilm reactor is a suitable technique for recycled pulp and paper wastewater (RPPW) treatment. The reactor shows high performances in terms of process stability, removal efficiency (> 70%) and biogas production. Anaerobic digestion is an efficient waste treatment technology that uses natural anaerobic decomposition to reduce the volume of waste while producing biogas. However, research is needed to strengthen microbial metabolism, biochemistry and the functioning of the rector to improve biogas production. The RPPW AD experiment with biofilm digester technology was stable throughout the operation period. The digester knows an overloaded in the last phase of the experiment which leads to an inhibition of biogas production.

In order to improve the efficiency of disease diagnosis and environmental monitoring, it is desirable to detect the concentration of proteins and metal ions simultaneously, since the current popular diagnostic platform can only detect proteins or metal ions independently. In this work, we developed a colorimetric microfluidic paper-based analytical device (µPAD) for simultaneous determination of protein (bovine serum albumin, BSA) and metal ions [Fe(III) and Ni(II)]. The µPAD consisted of one central zone, ten reaction zones and ten detection zones in one device, in which reaction solutions were effectively optimized for different types of chromogenic reactions. Fe(III), Ni(II) and BSA can be easily identified by the colored products, and their concentrations are in good accordance with color depth based on the established standard curves. The detection limits are 0.1 mM for Fe(III), 0.5 mM for Ni(II) and 1µM for BSA, respectively. Best of all, we demonstrated the efficiency of the µPAD with accurate detection of Fe(III), Ni (II) and BSA from river water samples within 15 minutes. The µPAD detection is efficient, instrument-free, and easy-to-use, holding great potential for simultaneous detection of cross type analytes in numerous diagnostic fields.

A superhydrophobic paper with excellent robustness was fabricated by roll coating with modified nano-TiO2. First, nano-TiO2 particles were hydrophobically modified by γ-aminopropyltriethoxysilane and 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (POTS). Then the paper coating composed of modified nano-TiO2 particles as pigments and epoxy resin (EP) as adhesives was coated on a paper surface to create the desired surface morphology and surface energy. Compared with the uncoated filter paper, the prepared paper showed an improved rough surface morphology owing to the uniform layer of TiO2 microclusters deposited on the fiber network. The superhydrophobic paper exhibited water contact angles (WCA) about 153° ± 1.5°, and water sliding angles (WSA) about 3.5° ± 0.5°, low surface adhesion and excellent bounce ability. The superhydrophobic paper can withstand a variety of wear and tear, such as tape stripping and knife scraping. The as-prepared superhydrophobic paper showed mechanical durability even after 20 wear cycles with sandpaper,thus sustaining excellent superhydrophobicity on the filter paper surface. Moreover, it remains fully functional even in environments with high concentrations of acid and alkali for 96 h. The superhydrophobicity was not affected after storage for 6 months in a natural environment. It was confirmed that the superhydrophobic paper surface exhibited excellent chemical stability, long-term stability and self-cleaning properties. The entire production process was operated under normal environment, without complex equipment; and, as such, has the possibility for large-scale production and application in industry.

The evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted the need for versatile diagnostic assays that can discriminate among emerging variants of the virus. Here we report the development and performance benchmarking of an inexpensive (approximately US$0.30 per test) assay for the rapid (sample-to-answer time within 30 min) colorimetric detection of SARS-CoV-2 variants. The assay, which we integrated into foldable paper strips, leverages nucleic acid strand-displacement reactions, the thermodynamic energy penalty associated with single-base-pair mismatches and the metal-ion-controlled enzymatic cleavage of urea to amplify the recognition of viral RNAs for the colorimetric readout of changes in pH via a smartphone. For 50 throat swab samples, the assay simultaneously detected the presence of SARS-CoV-2 and mutations specific to the SARS-CoV-2 variants Alpha, Beta and Gamma, with 100% concordance with real-time quantitative polymerase chain reaction and RNA sequencing. Customizable and inexpensive paper-based assays for the detection of viruses and their variants may facilitate viral surveillance.

Despite the green energy generation with low cost compared to conventional fuel cells, microbial fuel cells (MFCs) still suffer with anode related constraints including laborious pretreatment and modification process of conventional electrodes, limited bacterial loading capacity, and inferior extracellular electron transfer efficiency. Accordingly, this investigation explores the waste tissue paper derived three dimensional (3D) carbon aerogel (CA) integrated with cerium dioxide (CeO2) nanotubes decorated nitrogen-doped reduced graphene oxide nanosheets (NRGO) as a competent anode to address these technical complements. The direct growth of NRGO and CeO2 over CA in the form of freestanding and binder-free NRGO/CeO2(1:2)/CA alleviates the significant constrains of conventional anode fabrication. The 3D hierarchical architectures of CA with open porous structure provide easy access of bacteria, thus increases the bacterial colonies per unit volume. Furthermore, the hydrogen bonding between the interfacial oxygen atoms of CeO2 and lysine residues of the cytochrome c in bacteria yields excellent extracellular electron transfer efficiency. The electrostatic interaction between the NRGO and bacteria cells improves the bacterial adhesion and biofilm formation, leading to the compact biofilm formation for the improved direct electron transference. With the profits of above, the MFC with NRGO/CeO2(1:2)/CA demonstrates a maximum power output and good lifespan performances. The present exploration facts thus access advanced avenues to converting waste matters of tissue paper, human urine, and wastewater into profitable constituents for the development of efficient and durable power producing systems.

In low-resource settings, resilience to infectious disease outbreaks can be hindered by limited access to diagnostic tests. Here we report the results of double-blinded studies of the performance of paper-based diagnostic tests for the Zika and chikungunya viruses in a field setting in Latin America. The tests involved a cell-free expression system relying on isothermal amplification and toehold-switch reactions, a purpose-built portable reader and onboard software for computer vision-enabled image analysis. In patients suspected of infection, the accuracies and sensitivities of the tests for the Zika and chikungunya viruses were, respectively, 98.5% (95% confidence interval, 96.2-99.6%, 268 serum samples) and 98.5% (95% confidence interval, 91.7-100%, 65 serum samples) and approximately 2 aM and 5 fM (both concentrations are within clinically relevant ranges). The analytical specificities and sensitivities of the tests for cultured samples of the viruses were equivalent to those of the real-time quantitative PCR. Cell-free synthetic biology tools and companion hardware can provide de-centralized, high-capacity and low-cost diagnostics for use in low-resource settings. Double-blinded studies show that paper-based diagnostic tests and a companion portable device designed for use in low-resource settings perform well for the diagnosis of the Zika and chikungunya viruses in serum samples.

Production of laccase from Ganoderma lucidum RCK 2011 under solid-state fermentation (SSF) conditions was optimized using response surface methodology, resulting in an approximate eightfold increase compared to that in the unoptimized media. Further, the enzyme produced under SSF as whole fermented substrate (in situ SSF laccase) was found to be more stable than the in vitro enzyme (harvested by downstreaming processing of fermented wheat bran). Interestingly, the biobleaching potentials of both in situ and in vitro SSF laccases were comparable, saving 25% chlorine dioxide for achieving similar pulp brightness as obtained in the pulp treated chemically. The reduction in the demand of chlorine dioxide in the pulp bleaching sequence subsequently decreased the levels of adsorbable organic halogen (AOX) in the resulting effluents of the process by 20% compared to the effluents obtained from chemical bleaching sequence. Therefore, direct application of in situ SSF laccase in pulp biobleaching will be environmentally friendly as well as economical and viable for implementation in paper mills.

This study determined the effects of a static liquid culture system on shoot regeneration from citrus epicotyl explants. A mixture-amount experiment was used to determine the effects of zeatin riboside (ZR), 6-benzylaminopurine (BA), and indole-3-acetic acid (IAA) on two citrus types—citrange (Citrus sinensis ‘Washington’ L. Osbeck. × Poncirus trifoliata L. Raf var. Carrizo) and sweet orange (Citrus sinensis L. Osbeck var. ‘Ridge Pineapple’). A liquid culture system comprising a Petri dish, cellulose filter paper, and liquid culture medium was used. Shoot regeneration experiments were conducted over 6 wk that included 2 wk in the dark followed by 4 wk in the light. Three responses were measured: (1) number of explants forming buds and/or shoots, (2) number of explants with shoots > 2 mm, and (3) overall explant and shoot quality. The effects of paper disc number, liquid medium volume, and explant size on shoot regeneration were determined. High-quality shoots were produced from explants cultured in 5.25 to 12 mL medium volume and explant sizes ranging from 2 to 15 mm. The effects of the plant growth regulators were similar for the two citrus types and were as follows: (1) use of ZR or BA resulted in high-quality shoot production; (2) ZR and BA were not synergistic; (3) culture in 20 μM ZR resulted in the highest shoot production; (4) BA and IAA were strongly synergistic, with the greatest production with BA when IAA was included in the mixture; and (5) ZR and IAA were antagonistic, particularly with Ridge Pineapple.

The report of the American Association of Physicists in Medicine (AAPM) Task Group No. 132 published in 2017 reviewed rigid image registration and deformable image registration (DIR) approaches and solutions to provide recommendations for quality assurance and quality control of clinical image registration and fusion techniques in radiotherapy. However, that report did not include the use of DIR for advanced applications such as dose warping or warping of other matrices of interest. Considering that DIR warping tools are now readily available, discussions were hosted by the Medical Image Registration Special Interest Group (MIRSIG) of the Australasian College of Physical Scientists & Engineers in Medicine in 2018 to form a consensus on best practice guidelines. This position statement authored by MIRSIG endorses the recommendations of the report of AAPM task group 132 and expands on the best practice advice from the ‘Deforming to Best Practice’ MIRSIG publication to provide guidelines on the use of DIR for advanced applications.

Enzymatic hydrolysis is considered an efficient and environmental strategy for the degradation of organic waste materials. Compared to mesophilic cellulases, thermostable cellulases with considerable activity are more advantageous in waste paper hydrolysis, particularly in terms of their participation in synergistic action. In this study, the synergistic effect of two different types of thermostable Chaetomium thermophilum cellulases, the endoglucanase CTendo45 and the cellobiohydrolase CtCel6, on five common kinds of waste papers was investigated. CtCel6 significantly enhanced the bioconversion process, and CTendo45 synergistically increased the degradation, with a maximum degree of synergistic effect of 1.67 when the mass ratio of CTendo45/CtCel6 was 5:3. The synergistic degradation products of each paper material were also determined. Additionally, the activities of CTendo45 and CtCel6 were found to be insensitive to various metals at 2 mM and 10 mM ion concentrations. This study gives an initial insight into a satisfactory synergistic effect of C. thermophilum thermostable cellulases for the hydrolysis of different paper materials, which provides a potential combination of enzymes for industrial applications, including environmentally friendly waste management and cellulosic ethanol production.

Biomolecules in human body serve as biomarker for diagnosis of diseases, and paper-based biochips have become of much interest for development of biomolecule sensing. Cellulose micro-/nanofiber matrices consisting of paper allow not only capillary-driven flow without external pumping owing to abundant micro-/nanopores but also three-dimensional (3D) hierarchical micro-/nanostructures as 3D templates for microfluidic bioassays. Besides, colloidal and thermal evaporated metal nanoparticles on cellulose fibers offer huge opportunities in nanoplasmonic biosensing. Here, we review paper-based biochips including microfluidic paper-based assays and nanoplasmonic biosensors and further discuss micro-/nanofabrication of paper-based biochips and their applications in biomolecule detection.

Switching between metabolically active and dormant states provides bacteria with protection from environmental stresses and allows rapid growth under favorable conditions. This rapid growth can be detrimental to the environment, e.g., pathogens in recreational lakes, or to industrial processes, e.g., fermentation, making it useful to quickly determine when the ratio of dormant to metabolically active bacteria changes. While a rapid increase in metabolically active bacteria can cause complications, a high number of dormant bacteria can also be problematic, since they can be more virulent and antibiotic-resistant. To determine the metabolic state of Escherichia coli and Salmonella Typhimurium, we developed two paper-based colorimetric assays. The color changes were based on oxidoreductases reducing tetrazolium salts to formazans, and alkaline phosphatases cleaving phosphates from nitrophenyl phosphate salt. Specifically, we added iodophenyl-nitrophenyl-phenyl tetrazolium salt (INT) and methylphenazinium methyl sulfate to metabolically active bacteria on paper and INT and para-nitrophenyl phosphate salt to dormant bacteria on paper. The color changed in less than 60 min and was generally visible at 103 CFU and quantifiable at 106 CFU. The color changes occurred in both bacteria, since oxidoreductases and alkaline phosphatases are common bacterial enzymes. On one hand, this feature makes the assays suitable to a wide range of applications, on the other, it requires specific capture, if only one type of bacterium is of interest. We captured Salmonella or E. coli with immobilized P22 or T4 bacteriophages on the paper, before detecting them at levels of 102 or 104 CFU, respectively. Determining the ratio of the metabolic state of bacteria or a specific bacterium at low cost and in a short time, makes this methodology useful in environmental, industrial and health care settings.

The recognition and detection of metal ions present in biological and environmental samples have attracted great attention in recent years. Various analytical techniques are used to detect metal ions. Among these, the fluorescence technique is among the emerging methods because of its simplicity, selectivity, and applicability to bioimaging. Thus, this review particularly explores paper-based fluorescence chemosensors involved in metal ion detection. Significantly, the first section addresses relevant research on metal ion detection involving various techniques. In the second section, several sensing strategies such as photoinduced electron transfer, fluorescence resonance energy transfer, intramolecular charge transfer, chelation enhanced fluorescence, excited-state intramolecular proton transfer, and aggregation-induced emission for the detection of target metal ions (aluminum, copper, iron, lead, mercury, and zinc) are investigated. The third section particularly discusses the role of fluorescence sensor materials (e.g., fluorescein, rhodamine, naphthalimide, BODIPY, carbon dots, quantum dots) involved in the detection processes and their advantages and limitations. Overall, this article reviews 90 research articles on paper-based fluorescence chemosensors for metal ion detection published until 2021.

The bacterial diversity in terms of structure and community profile, with special reference to water quality in the wastewater treatment plant of Indian paper industries, is poorly understood. In the present work, characterization of bacterial diversity using 16S (V3-V4 region) rRNA gene amplicon sequencing data with reference to physicochemical parameters in the wastewater treatment plant of two paper industries has been carried out. Amplicon data analysis revealed the presence of bacterial taxa belonging to the phylum such as Bacteroidetes, Proteobacteria, Patescibacteria, Firmicutes, Actinobacteria, etc. Further, taxonomic classification upto genus level and functional analysis data indicated that genera such as Cloacibacterium, Aerococcus, Chryseobacterium, Microbacterium, Acinetobacter, Sphingobium, etc., were involved in the predicted metabolic pathways like carbohydrate metabolism, fatty acid and aromatic compounds biosynthesis as well as degradation. Canonical correspondence analysis confirmed a significant correlation between the microbial pollutions loads and physicochemical parameters. Further, the chemical oxygen demand, biochemical oxygen demand and total suspended solids exceeded the acceptable limits prescribed by Central Pollution Control Board New Delhi, Government of India, for discharge of wastewater. This study finds the correlation between the bacterial community residing in the polluted water of wastewater treatment plant and their environmental preferences. The presence of these bacterial diversity in the wastewater treatment plant of paper industries may affect the maintenance as well as paper quality. In future, it will provide a benchmark for the better understanding and management of wastewater treatment plant in paper industries across the globe.

In raising vegetable seedlings using cylindrical paper pots, the root substrates inside paper pots dry out fast mainly due to air spaces between paper pots created by chinks between the pot’s exterior and the holding tray. Frequent watering is necessary that contributes to the loss of nutrients by leaching during seedling production. This study was carried out to investigate the appropriate concentration of nitrogen required as a pre-planting fertilizer for growing fruit-bearing vegetable seedlings in cylindrical paper pots. For the experiment, the paper pots were made with the root substrate containing perlite (1–3 mm) and peat moss (10-mesh, 10–20% by volume) and they were placed into the 40-cell trays. The concentrations of all essential elements except nitrogen was equal in all treatments and the N concentration was adjusted to 0, 150, 250, 500, and 750 mg L−1 during the substrate formulation. Then, seedling grafts of cucumber, watermelon and tomato were transplanted and seeds of hot pepper were sown directly into the paper pots. The growth of cucumber, watermelon, and tomato plants were measured at 15, 18, and 21 days after transplanting and pepper at 5 weeks after seed sowing. The concentrations of macro-elements, pH, and EC of root substrates were analyzed every week. The pH of root substrates gradually increased during the seedling growth, but the differences in pH among N treatments is not significant. The EC in all treatments did not changed until one week after the transplanting of cucumber, watermelon, and tomato seedling grafts and 3 weeks after seed sowing of pepper. The concentration of Ca remained similar over time during the entire experimental period, but the concentration of Mg and K decreased 3 weeks after the seed sowing for the pepper growing root substrate. The concentrations of Ca, Mg, and K gradually decreased after one week of transplantation (cucumber, watermelon, and tomato). Based on the results, the optimal concentration of N required is 250 mg L−1 for tomato and 500 mg L−1 for cucumber, watermelon, and pepper respectively. In summary, the appropriate N concentration in the root substrate of paper pot is 250–500 mg L−1, and post-planting fertilization period is 1 week after transplanting for cucumber, watermelon and tomato and 3 weeks after seed sowing for hot pepper.

The occurrence of mineral oil hydrocarbons (MOH) in cellulose-based packaging is mainly due to the offset printing process where MOH are used as a ink pigments' solvent. The MOH migration from paper/paperboard to food is matter of concern for EFSA, members state authorities, consumers, and food industry. In this study, the feasibility to stabilize MOH by adding a sorbent into recycled paper obtained through a common washing process was investigated and the migration to wheat flour/Tenax® assessed. Among several white/pale yellow porous materials, organo-modified powder silica MCM-41-Si(CH3)3 showed the best combination between affinity for MOH (184% dw) and stability to thermal regeneration. A freshly issued newspaper with >3000 mg MOH kg-1 was used to produce recycled paper at a laboratory-scale plant. MCM-41-Si(CH3)3 was added at the pulping step (1% dw) and the sorbent-enriched pulp handled according to a washing paper production process with no effect on the paper optical brightness. The MOH content of the wheat flour in contact with the sorbent-enriched paper under accelerated migration conditions (15 days at 40 °C) resulted 20% of that contacted with control paper (4.3 ± 1.1 and 20.4 ± 5.5 mg kg-1, respectively), despite its contamination was 24% higher than the control. On the contrary, Tenax® contamination resulted 56.0 ± 10.0 and 47 ± 14.0 mg kg-1 when exposed to sorbent-enriched and control paper, respectively.

Bacillus anthracis (B. anthracis), the causative agent of anthrax disease, is a Gram-positive spore-forming bacterium which can be used as a threatening bioterrorism agent. We developed enzyme-linked immunosorbent assay (ELISA)-on-a-chip biosensors for rapid, sensitive analysis of B. anthracis spores based on two-dimensional, cross-flow chromatography. In order to establish optimal assay conditions, a polyclonal antibody and four monoclonal antibodies against B. anthracis were raised and examined to characterize their analytical sensitivity as well as specificity. The biosensor results showed that a monoclonal antibody pair not only offered a relatively low detection limit for B. anthracis compared to other antibody combinations, but also displayed no cross-reactivity with other microorganisms belonging to the Bacillus genus. For detection of ELISA enzyme signal (e.g., horseradish peroxidase), chemiluminescent detection in combination with cooled charge-coupled device enhanced the sensor performance in terms of assay time, compared to that achieved by colorimetry. Under optimal conditions, the biosensor was able to detect a minimum threshold of 5×103 and 5×102 spores/mL for two different B. anthracis strains, NCCP 12860 (Sterne) and NCCP 10666 (Haman #1), respectively. Furthermore, the chemiluminometric sensor was minimally affected by the presence of potential interferents in samples such as baby powder, skim milk, and sucrose, indicating its potential utility for the analysis of bioterrorism agents directly in the field.

Waste disposal from paper and pulp industry is of great environmental concern. Sludge from recycled paper mills favors colonization with different microbial species due to its chemical composition. In this environment, the microbiota can express enzymes that hydrolyze celluloses and hemicelluloses, such as cellulases, β-glucosidases, and xylanases. Understanding microbiota living in such disposal may give directions to what kind of enzymes or bioproducts may be possible to obtain from this microorganism and how to deal with the waste during the process. We have accessed microbial community associated with two steps in the recycled paper sludge generation by high-throughput DNA sequencing: fibrous residue, and wastewater sludge. Bacteroidetes, Proteobacteria and Firmicutes phyla represented more than 96% of the total. From the eukaryote perspective, Vorticella was the most frequent in fibrous residue samples while Acanthamoeba was the most common on wastewater sludge samples. Among the isolates cellulase activity was detectable only from fungi isolates. Half of the bacterial isolates presented xylanase activity, and most of them in high level of activity. Both a metabarcoding and culturing approaches are valuable tools for enzymatic screening in industrial waste disposal.

Thermostable cellulases have wide variety of applications and distinctive advantages, but their low titer becomes the hurdle in their commercialization. In the present work, an assessment of optimum levels of significant factors (temperature, moisture ratio, inoculum size, and ammonium sulfate) and the effect of their interactions on production of thermostable CMCase, FPase, and β-glucosidase by Thermoascus aurantiacus RCKK under solid-state fermentation (SSF) was carried out using central composite design (CCD) of response surface methodology (RSM). The study revealed 33, 13, and 8 % improvement in FPase, CMCase, and β-glucosidase production, respectively. Moreover, crude cellulase from T. aurantiacus RCKK efficiently hydrolyzed office waste paper, algal pulp (Gracillaria verulosa), and biologically treated wheat straw at 60 °C with sugar release of about 830 mg/ml, 285 mg/g, and 260 mg/g of the substrate, respectively. The thermostable enzyme from T. aurantiacus RCKK holds potential to be used in biofuel industry.

This study aimed to estimate the seedling performance of cylindrical paper pot (CPP) seedlings and to determine the optimal transplanting age of CPP seedlings based on seedling vigor. The studied vegetables were cucumber, tomato, paprika, and two varieties of cabbage, and the younger seedlings were obtained by shortening their raising period by 10 and 20 days with CPP. At the same transplanting age, the size of CPP seedlings was smaller pre-transplant but increased to a similar level to the plug seedlings soon after transplanting. The growth curves of leaf area and dry weight of younger CPP seedlings exhibited a steeper rise trend. The seedling vigor indicators, relative growth rate (RGR), net assimilation rate (NAR), were significantly increased in younger CPP seedlings of all vegetables, which were 10 or 20 days younger than plug seedlings. The compactness (CP) and seedling health index (SHI) of cucumber, and the leaf area ratio (LAR) and specific leaf area (SLA) of cabbage were significantly increased when shortened by 10 and 20 days, while the CP and SHI of paprika were significantly decreased when shortened by 20 days. Our results suggest that CPP may prevent the seedlings from overstretching and can provide a wild range of transplanting age choices to produce vigorous seedlings. Further, the seedling vigor indicators were successfully used to determine the transplanting age of CPP seedlings. The optimal transplanting age of CPP seedlings of tomato, paprika, and cabbage was 10 days younger than plug seedlings, whereas cucumber transplanting age could be decreased by either 10 or 20 days.

Investigation of the potential adverse effects of chemicals and drugs is essential during the drug development process. In vitro cell model systems have been developed over the past years towards such toxicity investigation. 96-well plate is the common platform for screening drug toxicity due to its simplicity. However, this platform only offers 2D cell culture environment and lacks the flow of solutions, which fails to provide the suitable environment for the cells to adequately metabolize the drugs, for the media to replenish, and for the metabolites and wastes to be removed. Microfluidic chips populated with human or animal cells, known as organ-on-a-chip (OOC), can reconcile many issues of in vitro cell models, such as the lack of extracellular matrix and flow as well as the species difference. However, OOC can be complicated to fabricate and operate. To bridge this gap, we utilized paper as a primary substrate for OOC, considering its fibrous structure that can mimic natural extracellular matrix, as well as a syringe pump and filter that are commonly available in most laboratories. Paper microfluidic model was designed and fabricated by wax printing on nitrocellulose paper, seeded and proliferated with liver cells (primary rat hepatocytes and HepG2 cells), and two paper substrates were stacked together to complete the paper model. To this paper-based liver cell model, the following drugs were added: Phenacetin (pain reliever and fever reducer), Bupropion (antidepressant), Dextromethorphan (antidepressant), and phosphate-buffered saline (PBS) as a control, all under a physiologically relevant flow rate. The combination of these drugs with Fluconazole (antifungal drug) was also investigated. Cell count, cell morphology, protein production, and urea secretion after drug treatment confirmed that the model successfully predicted toxicity within 40 minutes. This simple, paper-based liver cell model provided enhanced and faster cell response to drug toxicity and showed comparable or better behavior than the cells cultured in conventional 2D in vitro models.

All-inkjet-printing of transistors has received much attention for low cost and flexible integrated circuits. However, most flexible field-effect transistors (FETs) based on the emerging two-dimensional materials suffer from the high cost of substrate and electrode materials. The requirements for high-temperature synthesis and precise control in processing add another layer of complexity. To overcome these issues, low-cost flexible paper-based MoS2 FETs were fabricated by inkjet printing of MoS2 channel materials on paper. Additionally, we proposed and achieved the mask-less and low-temperature formation of source and drain electrodes on paper using in-situ selective-area copper reduction. A low sub-threshold swing of 80 mV/dec, high on/off ratio of 105, and very high turn-on current (Ion) of 200 μA of the paper-based flexible MoS2 FETs were demonstrated using the proposed low-cost and facile all-inkjet-printing technique. The all-inkjet-printing technique assisted by in-situ copper reduction opens new opportunities for low-cost and batch fabrication of paper-based electronic devices in ambient conditions.

Surface-enhanced Raman scattering (SERS) spectroscopy is an effective approach for trace-level detection of molecular substance. Plasmonic metallic nanostructures with high distribution densities and small gap widths are always expected for constructing SERS substrates. We report here a paper-based SERS substrate, where the three-dimensional (3D) network of paper fibers was used as the platform for supporting the gold nanoparticle clusters. Such a 3D arrangement of plasmonic porous clusters supplies high-density hotspots with large total volume and large surface area for the interaction with molecules. Comparison between different papers found that the filter papers commonly available in labs are the best choice. An enhancement factor higher than 104 has been achieved in the detection of R6G molecules. The preparation of such SERS substrates is very simple and convenient, implying low-cost, disposable, and environment-friendly SERS techniques. Furthermore, the paper-based flexible SERS substrates can be easily tailored into different shapes and sizes for fitting different applications.

Three-dimensional visualization of cellular and subcellular-structures in histological-tissues is essential for understanding the complexities of biological-phenomena, especially with regards structural and spatial relationships and pathologlical-diagnosis. Recent advancements in tissue-clearing technology, such as Magnified Analysis of Proteome (MAP), have significantly improved our ability to study biological-structures in three-dimensional space; however, their wide applicability to a variety of tissues is limited by long incubation-times and a need for advanced imaging-systems that are not readily available in most-laboratories. Here, we present optimized MAP-based method for paper-thin samples, Paper-MAP, which allow for rapid clearing and subsequent imaging of three-dimensional sections derived from various tissues using conventional confocal-microscopy. Paper-MAP successfully clear tissues within 1-day, compared to the original-MAP, without significant differences in achieved optical-transparency. As a proof-of-concept, we investigated the vasculature and neuronal-networks of a variety of human and rodent tissues processed via Paper-MAP, in both healthy and diseased contexts, including Alzheimer’s disease and glioma.

Media components were optimized using two-step statistical design of experiments for enhancing endoglucanase/carboxymethyl cellulase (CMCase) production by Trichoderma reesei RUT C30. A Placket-Burman design identified cellulose concentration and pH as the most significant variables, which influenced the CMCase activity. Central composite design was employed to optimize these selected parameters. The optimal activity was obtained at cellulose concentration 19.7 g/L and pH of 7.2. Under the optimized conditions, CMCase activity was 83.63 ± 1.86 IU/mL and filter paper activity was 2.58 ± 0.2 filter paper units per mL. Enzyme productivity was higher compared to previous reports. The enzyme produced from T. reesei was concentrated and was evaluated for deinking of printed paper, which demonstrated the suitability of the enzyme for this application.

Sixty fungal cultures were isolated from agricultural soil, industrial soil, forest canopy soil having decomposed leaf litter and compost samples collected from different regions of India. Fifteen fungal cultures were selected qualitatively for the production of xylanase and cellulases and were identified employing ITS, NS and MNS primers. The enzyme cocktail consisting of 3811 IU g(-1) of xylanase and 9.9 IU g(-1) of cellulase from Trichoderma longibrachiatum MDU-6 was selected quantitatively for the deinking of diverse paper wastes. The enzyme production increased two fold when produced at tray level in comparison with flasks. The enzyme cocktail was effective in the deinking of old newspaper samples with significant removal of chromophores, phenolics and hydrophobic compounds and less sugar loss. While in case of examination papers and laser printed papers, ink removal was not very significant. Moreover, the sugar loss was significantly high in case of examination papers. The deinking results were further confirmed with FTIR analysis. Deinked newspaper pulp sample shows brightness of 52%, which was 9.6% high than its control sample. The ERIC value for deinked newspaper pulp was found to be 655.9 ppm. Thereafter, the deinked newspaper pulp was examined under light microscope after differential staining with safranin and malachite green and also examined under scanning and transmission electron microscope, which revealed fibrillation and perforation.

Trichoderma reesei strain Rut-C30 was modified with enhanced beta-glycosidase (BGL) activity to balance the cellulase system and generated laccase (LAC) protein for lignin degradation. Initially, the binary plasmid p1300-w1 was constructed to express T. reesei bgl2 under the control of promoter P pki and T-nos terminator. Random insertion was performed via Agrobacterium tumefaciens-mediated transformation. A total of 353 mutants were obtained, and 34PTrb2 was exceptionally stable with increased FPA and BGL activity after screening for extracellular enzyme activity. Subsequently, 34PTrb2 was used as parent strain via the same method to insert the lac gene from Fomes lignosus, with promoter P gpd , followed by cbh1 signal peptide trss and T-nos as terminator. Several mutants successfully expressed enzyme LAC with stable activity of approximately 0.13 U/mL. The mutant 15Gsslac increased activity by 40.4% FPA compared with that of the host Rut-C30.

A simple paper-based colorimetric biosensor based on immobilized tyrosinase and 3-methyl-2-benzothiazolinone hydrazone (MBTH) was developed for assessing total polyphenol content (TPC) of various green tea beverages. The patterned biosensing zone of the paperbased biosensor showed a sensitive response to catechin (a typical green tea polyphenol) by generating pink color adducts that can be captured for further color image analysis using a scanometric method. This color change can be connected to the TPC of the samples. The analytical performance of the biosensor in scanometric set-up was optimized. The biosensor showed a response time of 13 min in the linear range between 0.08-1.03 mM of catechin (r = 0.9979). The detection limit (LOD) of the biosensor was 0.071 mM while reproducibility was found at 3.11% RSD (relative standard deviation). TPC of green tea beverages was assessed by the biosensor, and the results were in accordance with the UV/Vis spectrophotometric method.