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Cationic cellulose, despite its long history, has yet to find a place in the paper industry. However, recent research is evaluating the potential of its nanoscale forms. Likewise, the processes of Western manufacturers are optimized for wood pulps, relegating non-wood crops to specific products that, as also proposed by current research, could include nanocellulose. We combined these trends with the existing knowledge of the strong adsorption of poly(diallyldimethylammonium chloride) (polyDADMAC) on cellulosic fibers, which can be deemed a non-covalent kind of cationization. For that, polyDADMAC was first anchored to refined hemp pulps, under conditions that allowed the deprotonation of the primary hydroxyl groups of cellulose. The fiber surface remained positively-charged even after thoroughly washing the samples, owing not only to the small proportions of acidic hemicelluloses and lignin, but also to stable ion-dipole interactions. This non-covalent cationization was found to follow pseudo-second order kinetics, indicating that diffusion through the fiber was the rate-controlling step. PolyDADMAC-containing fibers were then fibrillated by high-pressure homogenization. The surface charge of cationic nanocellulose was greater than that of the starting fibers, as the specific surface area increased. Nonetheless, polyDADMAC caused agglomeration of fibrils to a certain extent. As a drawback, when applied in papermaking, cationic nanocellulose lowered air permeability to a lesser extent than non-cationized nanofibers. As an advantage, the tensile index increased by up to 57% in the absence of any retention agent Authors wish to acknowledge the financial support of the Spanish Ministry of Science and Innovation to the Project CON-FUTURO-ES (PID2020-113850RB-C22). Marc Delgado-Aguilar and Quim Tarrés are Serra Húnter Fellows Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier

This chapter mainly focuses on the recent developments made in rapid detection of cancer cells using novel paper-based analytical devices (PADs). Due to their simplicity, portability and biocompatibility, PADs have gained great attention in recent years for rapid detection of biomarkers. Since cancer has become an increasing worldwide concern, there stands an imminent requirement for minimally invasive detection and monitoring techniques. The progress made in paper-based detection of cancer biomarkers has proven to hold great potential for the development of point-of-care (POC) diagnostic devices for early detection of tumor cells. In this chapter, after an introduction on paper diagnosis, we will provide a brief explanation on the fabrication methods used for PADs. Then recently developed sensors based on colorimetric, fluorescence, chemiluminescence (CL), electrochemical, electrochemiluminescence (ECL) and surface-enhanced Raman scattering (SERS) techniques will be elaborated. In the end, current limitations and problems hindering the commercialization of paper-based sensors will be pointed out.

[EN] Nowadays, miniaturization and portability are crucial characteristics that need to be considered for the development of water monitoring systems. In particular, the use of handheld technology, including microfluidics, is exponentially expanding due to its versatility, reduction of reagents and minimization of waste, fast analysis times and portability. Here, a hybrid handheld miniaturized polymer platform with a paper-based microfluidic device was developed for the simultaneous detection of nitrite and nitrate in real samples from both, fresh and seawaters. The platform contains an ionogel-based colorimetric sensor for nitrite detection and a paper-based microfluidic device for the in situ conversion of nitrate to nitrite. The platform was fully characterized in terms of its viability as a portable, cheap and quick pollutant detector at the point of need. The calibration was carried out by multivariate analysis of the color of the sensing areas obtained from a taken picture of the device. The limits of detection and quantification, for nitrite were 0.47 and 0.68mgL-1, while for nitrate were 2.3 and 3.4mgL-1, found to be within the limits allowed by the environmental authorities, for these two pollutants. Finally, the platform was validated with real water samples, demonstrating its potential to monitor nitrite and nitrate concentrations on-site as a first surveillance step before performing extensive analysis. This project has received funding from the European Union Seventh Framework Programme (FP7) for Research, Technological Development and Demonstration under grant agreement no. 604241. The funding support from Gobierno de España, Ministerio de Ciencia y Educación de España” under grant PID2020-120313 GB-I00/AIE/10.13039/501100011033, and Gobierno Vasco Dpto. Educación for the consolidation of the research groups (IT1271-19) are also acknowledged. RC-C acknowledges funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 778001. Special thanks to (SGIker) of the University of the Basque Country (UPV/EHU). FB-L and LB-D acknowledge the “Red de Microfluídica Española” RED2018-102829-T.

Electrochemical paper-based analytical devices (ePADs) are receiving increasing attention in recent years, overcoming the publication number of colorimetric paper-based analytical devices in the literature. This chapter covers recent advances in the manufacturing of ePADs for chemical analysis. Initially, an introduction about its beginning in the literature and mainly practical theoretical principles are discussed. The following sections present how the devices are being fabricated and used in the literature, exploring their advantages and limitations and describing electrochemical sensing detection and future outlooks.

This chapter presents and discusses the most usual methodologies for colorimetric detection on paper-based analytical devices (PADs). State of the art associated with pioneering, popularity, physical aspect, surface modifications, instrumental and instrumental-free colorimetric measurements are carefully presented. Moreover, a side-by-side comparison among the most usual colorimetric detection modes on PADs was performed using a well-known complexometric reaction model. The pros and cons were discussed to show their advantages for chemical analysis.

Fluorescent paper-based analytical devices (FL PADs) are receiving increasing attention in recent years, owing to the development of new technologies for the fabrication of brighter fluorophores and phosphors, especially nanomaterials. This chapter covers recent advances in the construction of FL PADs for qualitative and quantitative assays. It commences by introducing the most often used fluorescent probes, including organic dyes, quantum dots, carbon dots, upconversion nanoparticles, and their use as reporters. The second part presents the fluorescence response produced by the PADs, which can be either brightness-based (“turn-on” and “turn-off”) or color-based (ratiometric fluorescence). We approach the different signal responses by presenting recent examples of developed FL PADs, exploring their advantages and limitations, and describing their fabrication technologies and sensing mechanisms.

This chapter describes the concept of paper space. Covered are the primary reasons for using paper space, how to get in/out of paper space, and how to set up title blocks (layouts), viewports and their properties, viewport scale assignments, controlling what is visible in viewports, setting up text and dim styles in viewports, and the annotative concept.

The number of citations a peer-reviewed article receives is often used as a measure of its importance and scientific impact. This paper identifies, describes and categorizes the highly cited papers in addiction research on cannabis, heroin, cocaine and psychostimulants. Highly cited papers were identified in the Web of Science Core Collection database. Several bibliometric indicators were calculated. Social network analysis was applied to draw groups of authors and institutions with the greatest number of collaborations and co-words. The number of citations for the top 100 cited articles ranged from 649 to 4,672. The articles were published in 40 journals. The subject category Substance Abuse included 10 papers. The United States was the most productive country (79 papers), followed by the United Kingdom (9). The main funding institutions were the National Institutes of Health in the United States. The network of collaboration between authors distributes the 352 researchers into 53 groups. The three most cited works address the neural basis of drug craving as an incentive-sensitization theory of addiction, the clinical and research uses of the Addiction Severity Index, and the neurocircuitry of addiction. Scientific literature on addictions is widely dispersed both in multidisciplinary and specific journals of neurology, psychiatry and addictions, with relatively few publications providing most of the citations. An ongoing challenge for this field is the concentration of highly cited papers coming from a select number of countries, with the United States being the research hub of the world, with the highest volume of publications and total citations., This work have been funding by Servicio de Drogodependencias (PMD/UPCCA-València). Concejalía de Sanidad y Consumo. Ajuntament de València.

India is a vast country with around 850 large paper industries. It is ranked 17 in the highest polluting industries in India, approximately 190–200 m3 of water is needed to produce a ton of paper. Around 240–250 chemicals have been identified in effluents, which are produced at different stages of papermaking in paper industry. The pulp and paper industry is typically associated with pollution problems related to color, suspended solids, high biochemical oxygen demand (BOD), chemical oxygen demand (COD), organic halogens lignin and its derivatives, dioxin, furan, and chlorinated compounds. These compounds are highly toxic in nature causing strong mutagenic effects, physiological impairment, and they are ecoestrogens. Although numerous studies have looked at methods for the treatment of color, COD, BOD, etc. of pulp and paper effluents, the problem still persists. Biological treatment uses a number of microorganisms including bacteria, fungi, and actinomycetes to degrade the xenobiotic compounds present in pulp and paper industry effluent. The need for cleaner production programs has been felt in recent times by the paper industry by way of a resource and waste minimization concept. In India efforts have been going on for years to improve housekeeping, optimize process parameters, increase recycling, and adopt improved technology. This chapter aims at highlighting the processes used during the manufacture, sources, and types of waste generated and treatment options available for improving the quality of waste to be discharged.

The discharged wastes from the pulp paper industry contain ligninocellosic material along with other co-pollutants even after secondary treatment. Moreover, the effluent contains a high amount of pH, total suspended solid, total dissolved solid, total solid, biological oxygen demand, and chemical oxygen demand along with heavy metals above the permissible limits. Several studies have concluded that white-rot fungi produced extracellular phenol oxidases which can effectively decompose lignin and other organic pollutants from the contaminated site. Furthermore, various types of persistent organic pollutants and endocrine-disrupting chemicals i.e. nonacosane; heptacosane; pentadecanoic acid, 2-benzisoxazole; hexadecanoic acid and octadecenoic acid are also present in pulp paper industry effluent that can cause aquatic toxicity and hormonal disturbance in the environment. The ligninolytic enzymes of white-rot fungi get a wide substrate particularity and have been involved in the transformation and mineralization of organic pollutants to systemic similarities to lignin. Moreover, continuous widespread land and groundwater pollution as well as surface water have brought this issue to the forefront, and cleaning up of such pollution is still a severe economic challenge for the society. The use of indigenous white-rot fungi for remediation of wastes from the disposal site of the pulp paper industry gives a very relatively novel economic solution for many of our risky environment challenges.

Enzyme use has provided boost to the technoeconomics of many industrial processes. In this chapter, we summarize different cellulase-based industrial processes for preparation of paper, pulp, brewing products, and different foods. This review presents a brief chemistry and mechanism of cellulose degradation by the cellulase enzyme. Also, cellulase production abilities of many microbial species have been addressed in this chapter. Cellulase plays a major role in production of good-quality paper and pulp. It’s used to debark the biomass and to remove lignocellulosic part. This enzyme also has application in recycling of used paper by deinking and biobleaching. Cellulase enhances freeness and drainage ability of the fibers without compromising the brightness of the fibers. In brewing industry, cellulase in combination of other enzymes is used to extract the more sugar for better-quality alcohol production. Cellulases have a wide range of potential applications in food and beverage processing, production of fruit and vegetable juices, and improvement of methods for extraction, clarification, and stabilization.

In this paper, we report the performance of paper pulp as an innovative viscosity modifying admixture (VMA) for cement composites. Two different levels of fineness were obtained by mechanical milling of the same source of paper pulp. Their effects on viscosity modification, hydration kinetics, autogenous shrinkage, and compressive strength of cement grouts were measured, and their structural integrity at high pH was assessed. A new parameter was proposed to quantify nonlinearity induced by VMAs. Results showed that the hierarchical structure of paper pulp makes it possible to activate bridging flocculation and swelling mechanisms of hydrophile paper pulp fibers at different levels to produce versatile VMAs. The coarser milled paper pulp fibers mainly influences the plastic viscosity. By contrast, the milled paper pulp consisting of ultra-fine fibers significantly modifies both plastic viscosity and dynamic yield stress, induces more nonlinearity in the mixtures, and increases compressive strength of mortars at low dosages.

This study's focus was to develop a potential pathway for recycling of the paper mill sludge compost (PMSC) in brick making. Composting reduces the paper mill sludge (PMS) moisture content considerably and shredding becomes easier. The addition of PMSC leads to an increase of porosities in bricks and makes them lighter, besides delivering energy to the firing process from burning organics. Lighter construction materials help minimize construction outlay by reducing labour and transportation costs and lesser expense on foundation construction. The variability in the experimental data and the brick properties were investigated for two types of soils, typical in the brick industry of India (alluvial and laterite soil), blended with PMSC in five mix ratios (0%, 5%, 10%, 15% and 20%). The samples of oven-dried bricks were fired at two different temperatures (850 and 900 ˚C) in an electrically operated muffle furnace representing typical conditions of a brick kiln. Various properties of bricks were analyzed which included linear shrinkage, bulk density, water absorption and compressive strength. Conclusions were drawn based on these properties. It was found that the addition of PMSC to the alluvial and laterite soil by up to 10% weight yield mechanical properties of fired bricks compliant with the relevant Indian and ASTM codes. Toxicity characteristic leaching procedure (TCLP) tests showed that PMSC incorporated fired bricks are safe to use in regular applications as non-load-bearing and infill walls. This study is timely in light of the European Green Deal putting focus on circular economy. Besides, it fulfills the objective of UN sustainable development goals (SDG).

A simple cellulosic (C6H10O5)n substance, paper has many applications in addition to its use in writing, painting, and packaging. Papers have long been used in analytical chemistry; however, recently, their use in the development of cheaper portable sensors and energy storage devices has been explored. These paper-based environmental sensing devices are providing faster and simpler contaminant detection, along with the removal of sample storage and transportation. In addition to chemical pollutant detectors, the paper-based sensors are also being developed for the gases and volatile compounds. Such paper-based sensors will be very useful in rapid detection of toxic gases during any emergency. . These easy and cheap paper-based devices will be very useful for the developing countries, where environmental pollution concentration is very high and the sophisticated analytical laboratories are not easily accessible. Along with the exponentially increasing in pollution level, our energy demands have also increased by the same pace. Modern-day electronic devices and electric vehicles need robust energy storage devices, and our conventional batteries are not efficient for it. Therefore the supercapacitor has emerged as a solution to this problem; it is a rechargeable, high energy density and quick-release energy storage device, and the use of paper in its development let it to be used in deformable electronic devices.

While current trends in Green Analytical Chemistry aim at reducing or simplifying sample treatment, food usually comprises complex matrices where direct analysis is not possible in most cases. In this context, sample treatment plays a pivotal role. Biogenic amines are naturally formed in many foodstuffs due to the action of microorganisms, while their presence has been associated with adverse health effects. In this work, the extraction of seven biogenic amines (cadaverine, histamine, phenylethylamine, putrescine, spermidine, spermine, and tyramine) from beer samples has been simplified using laboratory filter paper as sorbent without any further modification. The analysis of the eluates by direct infusion mass spectrometry reduces the time of analysis, increasing the sample throughput. This simple but effective method enabled the determination of the analytes with limits of detection as low as 0.06 mg•L−1 and relative standard deviations better than 11.9 %. The suitability of the method has been assessed by analyzing eight different types of beers by the standard addition method.

With the objective to obtain more sustainable production processes, the biorefinery network is integrated with traditional pulp and paper industries. A systematic framework with computer-aided tools consisting of synthesis, design and innovation stages has been applied to determine the biorefinery-integrated pulping process. An integrated network of succinic acid production and black liquor gasification for dimethyl ether (DME) production linked to an existing Soda pulping process is identified as the best option for increased profit, which also reduces pollutant emissions through integration of innovative CO2 capture and utilization (CCU) steps to form the biorefinery-integrated-Soda-pulping network (BIS). This paper aims at also designing a sustainable biorefinery-integrated-Kraft-pulping network (BIK). Three integration scenarios are considered for further study: (I) the production of gasification-based dimethyl ether (DME); (II) the coproduction of DME and succinic acid (SA); and (III) the co-production of DME and SA coupled with CCU. The best scenario is found to be Scenario II, which exhibits the best economic performance with 74% increase in profit compared to the conventional process. Scenario III achieves the highest energy efficiency at 39% and improved environmental performance, a 65% reduction of CO2 emission compared to the conventional process, with only 0.7% profit reduction. The BIK option shows improved performance in terms of economic and environmental improvements compared to the BIS network, confirming that the integrated biorefinery network can transform the conventional Kraft pulping process to a more sustainable process with increased profit.

Microfluidic paper-based analytical devices, so-called μPADs, were presented for the first time by Whitesides and colleagues in 2007. Since then, several research groups have focused on designing, synthesizing, and investigating the role of microfluidic paper-based devices in different applications including biosensors, drug delivery, gene delivery, and so on. In this chapter, we focused on different aspects of them, to provide an applicable perspective as well as review the recent advances in this field.

9 figures, 7 tables.-- Supplementary information available.-- © 2021. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0, In this paper, lignin-activated carbon xerogels from the black liquor of the paper industry were synthesized by the sol-gel polycondensation of resorcinol and lignin with formaldehyde, NaOH, and water. The sol-gel was prepared at three Lignin/(Lignin+Resorcinol) mass ratios of 0, 13, and 27%. A portion of sol-gel was functionalized with a no-common crosslinking agent, cyanuric chloride (CC) saturated in 1,4-dioxane, to introduce some nitrogen functional groups on the surface. The sol-gels non- and functionalized were dried and activated with H3PO4 at a mass ratio of 1:1 at 450 °C. After the functionalization with the CC and activation process, the superficial nitrogen content percentage increased to 7 wt%, where the most prevalent functionality was N-pyrrole. The sample with a high percentage of nitrogen groups did not show the best electrochemical behavior (112 F g−1 at 0.125 A g−1). However, increasing lignin content up to 27% without functionalization improved the gravimetric capacitance value of 149.5 F −1. These results are mainly attributed to electrostatic effects and the high presence of phosphorus functionalities introduced after the activation process that enhance the surface wettability of the electrodes. Furthermore, the analysis of the variance confirmed that the CC impregnation process did not favor gravimetric capacitance. Lignin can be considered as an excellent substitute for resorcinol partially to produce bio-based activated carbon xerogels and use them as electrodes for supercapacitors and reduce production costs., The authors acknowledge the financial support of CIDI-UPB for projects No 113B-05/13–21, 816B-06/A-19, and Colciencias for the financial support of the project code No. 21065842324.

Nowadays, there are strong efforts in developing new technology for rapid detection of specific DNA sequences for environmental monitoring, forensic analysis and rapid biomedical diagnosis applications. That is where microfluidic paper-based analytical devices are positioned as suitable platforms for the development of point of care analytical devices, due to their simple fabrication protocols, ease of use and low cost. Herein, a methodology for in situ single strand DNA detection by using a colorimetric assay based on the formation of a DNAzyme within a paper substrate was developed. A DNAzyme that could only be formed in the presence of a specific sequence of the Y human amelogenin gene was designed. The performance of the DNAzyme was followed colorimetrically first in solution and then in paper substrates. The reaction was found to be specific to the Y fragment selected as analyte. The DNAzyme reaction on paper enabled the unequivocal colorimetric identification of the Y single strand DNA fragment both qualitatively, with the naked eye (143 ng), and quantitatively by image analysis (45.7 ng). As a proof of concept, a microfluidic paper-based device, pre-loaded with all DNAzyme reagents, was characterized and implemented for the simultaneous detection of X and Y single strand DNA fragments. This work was supported by Gobierno de España, Ministerio de Economía y Competitividad, with Grant No. BIO2016-80417-P; funding from Basque Government (Grant: IT1271-19) and European Union funds: DNASURF (H2020-MSCA-RISE-778001). E.A.-H. acknowledges funding from the Basque Government, Department of Education, for predoctoral fellowship 2016.

Antibiotic resistance (AR) is becoming a worldwide threat due to the increasing occurrence of antibiotic-resistant pathogenic bacterial strains. There is a general consensus about the potential implications of the use of antibiotics in livestock on the onset of antibiotic resistant bacteria (ARB), mainly through meat consumption. However, the ever-increasing use of reclaimed wastewater (RWW) in agriculture may also contribute significantly to the non-accounted exposure to antibiotics, ARB, and antibiotic resistance genes (ARGs). This position paper aims at evaluating the current knowledge concerning the occurrence of antibiotics, ARBs, and ARGs in edible parts of different common crops irrigated with RWW. We will discuss which regulations on the use of RWW may contribute to the minimization of the prevalence of these contaminants in crops, and provide recommendations on how to minimize the impact of these practices., The authors would like to acknowledge the COST Action ES1403 NEREUS “New and emerging challenges and opportunities in wastewater reuse”, supported by COST (European Cooperation in Science and Technology, www.cost.eu) for enabling the collaboration among the authors of the paper.

Interest in water treatment by electrochemical methods has grown in recent years. Electrochemical oxidation has been applied particularly successfully to degrade different organic pollutants and disinfect drinking water. This study summarizes the effectiveness of the electrochemical oxidation technique in inactivating different primary biofilm forming paper mill bacteria as well as sulfide and organic material in pulp and paper mill wastewater in laboratory-scale batch experiments. Three different electrodes, boron-doped diamond (BDD), mixed metal oxide (MMO), and PbO2, were employed as anodes. The impact on inactivation efficiency of parameters such as current density and initial pH or chloride concentration of synthetic paper machine water was studied. The electrochemical behavior of the electrodes was investigated by cyclic voltammetry with MMO, BDD, and PbO2 electrodes in synthetic paper mill water as also with MMO and stainless steel electrodes with biocides. Some suggestions on the formation of different oxidants and oxidation mechanisms were also presented during the treatment. Aerobic paper mill bacteria species (Deinococcus geothermalis, Pseudoxanthomonas taiwanensis, and Meiothermus silvanus) were inactivated effectively (>2 log) at MMO electrodes by current density of 50 mA/cm2 and the time taken was 3 min. Increasing current density and initial chloride concentration of paper mill water increased the inactivation rate of D. geothermalis. The inactivation order of different bacteria species was M. silvanus > P. taiwanensis > D. geothermalis. It was observed that inactivation was mainly due to the electrochemically generated chlorine/hypochlorite from chloride present in the water and also residual disinfection by chlorine/hypochlorite occurred. In real paper mill effluent treatment, sulfide oxidation was effective with all the different initial concentrations (almost 100% reduction, current density 42.9 mA/cm2) and also anaerobic bacteria inactivation was observed (almost 90% reduction by chloride concentration of 164 mg/L and current density of 42.9 mA/cm2 in 5 min). Organic material removal was not as effective when comparing with other tested techniques, probably due to the relatively low treatment times. Cyclic voltammograms in synthetic paper mill water with stainless steel electrode showed that H2O2 could be degraded to radicals during the cathodic runs. This emphasizes strong potential of combined electrochemical treatment with this biocide in bacteria inactivation in paper mill environments. The results of the experiments showed that electrochemical oxidation could be used in paper mill waters for planktonic bacteria removal. Applying this technique together with some biocides can enhance the oxidation process, keeping the paper mill pipelines clean of slime formed by bacteria. Electrochemical oxidation is also a promising preliminary or tertiary treatment process in pulp and paper mill wastewater treatment, especially against refractory organic compounds which cannot be removed by biological processes.

Paper-based microfluidic devices have undergone rapid development and offered a promising low-cost platform for disease diagnostics in poor-resource areas. Recently, paper-hybrid microfluidic devices have attracted much attention and been applied in various low-cost point-of-care testings, due to multiple merits derived from both paper and other substrates. This chapter summarizes the recent progress of low-cost paper and paper-hybrid microfluidic devices for rapid diagnostics of human diseases. The commonly used fabrication techniques are first introduced, and the applications of numerous paper and paper-hybrid microfluidic devices are then elaborated with an emphasis on rapid disease diagnostics in terms of the nature of biomolecules in three major categories, namely, protein-, gene-, and cell-based diagnostics. Both advantages and disadvantages of using these devices are discussed, followed by the perspectives for broad applications in low-cost diagnostics.

In this chapter, we have discussed the advancements in the conventional diagnoses and their paradigm shift towards the affordable, sensitive, reliable, user-friendly, and deliverable diagnostics-based approaches. Among various alternatives, paper-based technologies have greatly been acclaimed for delivering sensitive biosensing. Paper being a cheaper and adequate substrate; it has been widely explored for the fabrication of biosensor determining the clinically relevant molecules/biomarkers. This chapter comprehensively describes the properties of paper-based platforms in terms of achieving the sensitive detection followed by the discussion on various adopted biosensing systems including the dipsticks, lateral flow assays (LFA), microfluidic paper-based devices (μ-PAD), and most advanced peripheral accessories assisted paper-based biosensors for clinical detections/diagnoses. Following this section, we have incorporated a brief discussion on commonly used clinical samples and their interaction/behaviour to the paper-based substrates. We have also discussed the prominent challenges associated while handling these clinical samples in the paper-based modules for achieving better analytical performances. The discussion on different strategies for addressing the persisting challenges to paper-based platforms and their recent advancements have also been incorporated to put more insights.

The ideal environmental sensing devices should include following features: autonomous operation; robustness to sustain the extreme environmental stresses, features to undertake quantitative and qualitative measurements with desired sensitivity and reproducibility. The requirement for portable and self-operated devices is crucial in gaining insights to understand potential environmental hazards in all core environments, namely, water, air, land, and biological matrices. There are a variety of environmental contaminants, which require regular monitoring to assess the impacts and to arrive at remedial measures. Several standard analytical techniques are available for monitoring of these contaminants, including laboratory-based spectroscopic and chromatographic techniques. These techniques are highly sensitive and selective; however, they are exorbitantly costly, lack portability as they are bulky, and require highly skilled professional operators and laborious operations. Therefore big challenge remains in developing low-cost, portable, and highly efficient field testing devices. Recently microfluidics has evolved as a reliable technology for affordable and portable detection platforms. Recent efforts to develop microfluidic devices mainly focused on the development of integrated microfluidic devices by incorporating fluidic components and analytical and detection techniques into single platform. Tailored microfluidic devices are being developed to address a variety of applications, including determination of air, water, and food quality and detection of pathogens, biofilms, and environmental contaminants. Paper-based microfluidic devices have been developed recently to reduce the cost and due to other advantageous features such as disposability, portability, and requirements of low volume of samples. The chapter offers a comprehensive insight into recent developments pertaining to materials and techniques for detection and fabrication of paper-based microfluidic devices.

Biosensors are promising tools in several areas such as clinical diagnosis, food analyses, environment monitoring, and in other fields, where rapid and reliable analyses are needed. Today they are represented on the market worldwide by an increasing number of paper-based electrodes working in these areas. Paper-based electrodes for glucose monitoring have been commercially available for about 25 years. Apart from glucose monitoring by using paper-based electrodes, commercials tests are now available for metabolites, human chorionic gonadotrophin, C-reactive protein, troponin, myoglobin, human immunodeficiency virus, influenza A and B, streptococcus A, Helicobacter pylori, adenovirus and rotavirus, malaria, tuberculosis, hepatitis A/B/C, and cancer biomarkers measurements in human fluids. Other application points of these paper-based commercial tests are food, environment, and biothreat applications. Such tests are successfully applied in home, office, hospitals, and clinics. In this chapter, the commercial tests used for clinical, food, environmental, and biothreat analyses in global market are reviewed and the specific features of these tests are summarized.

Paper-based sensing platforms are one of the most powerful tools for point-of-care diagnostics. The ease of use while ensuring low production costs of such devices is the key for paper-based technologies to find their way to a successful commercialization. Thus, all steps in the analytical process chain from sample interface, sample preparation, signal amplification to signal transduction and data analysis have to be integrated in a single diagnostic platform. In this chapter, we provide a comprehensive and critical overview on recent developments towards integrated paper-based platforms in academia and industry. Herein, innovative solutions are discussed with respect to their sampling methods such as invasive and non-invasive approaches. We also address the requirements and challenges for the sampling and analysis of the different body fluids. Finally, we present our views about the future perspectives, challenges, and opportunities of the integrated paper-based devices.

The fluorescence-based detection of biological complexes on solid substrates is widely used in microarrays and lateral flow tests. Here, we investigate thiol-ene micropillar scaffold sheets (“synthetic paper”) as the solid substrate in such assays. Compared to state-of-the-art glass and nitrocellulose substrates, assays on synthetic paper provide a stronger fluorescence signal, similar or better reproducibility, lower limit of detection (LOD), and the possibility of working with lower immunoreagent concentrations. Using synthetic paper, we detected the antibiotic enrofloxacin in whole milk with a LOD of 1.64 nM, which is on par or better than the values obtained with other common tests, and much lower than the maximum level allowed by European Union regulations. The significance of these results lays in that they indicate that synthetically-derived microstructured substrate materials have the potential to improve the performance of diagnostic assays., We gratefully acknowledge the financial support from the European project ND4ID, and Ministry of Science, Innovation and Universities Spain (IMMUNO-QS, SAF2015-67476-R and QS4CF, RTI2018-096278-B-C21). We thank Dr Ana Sanchis from IQAC-CSIC for providing the glass slides and assistance in operating the spotter and scanner, Dr David Santos for the MALDI-TOF tests, and Dr Nuria Pascual for providing the primary antibodies.

This chapter describes the importance of PADs for biomarker detection. The screening of disease markers and other biomolecules that related to health conditions have play important roles for an indication of the risk from infections and other diseases. Paper-based analytical devices (PADs) is an excellent option for applications of biomarker detection because it contains all advantages which arise from the paper material. Moreover, the uncomplicated techniques including electrochemistry and colorimetry can be easily applied on PADs for the analytical detection. The detection method can be categorized into three main topics: enzymatic methods, immunoassays, and DNA sensors. Following the main context, other interesting applications also present in this chapter.