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Paper-based analytical devices (PADs) are becoming increasingly popular for drug analysis in various matrices. These affordable, portable platforms come with a range of benefits, such as their user-friendly design, straightforward operation, and minimal need for sample preparation. This study evaluates the potential applications of PADs in drug testing with a particular emphasis on the adaptability of PADs in terms of their ability to handle various types of samples during the testing process. In this study, the design, manufacturing, and performance of PADs for drug detection, as well as the influence that different biological samples have on the performance of PAD performance were investigated. PADs are discussed in this paper, with respect to their applications in forensic sample analysis, point-of-care testing and illicit drug testing. The study demonstrates the flexibility of PADs as platforms for drug testing in varied matrices. The authors highlight the fact that PADs are inexpensive, portable, user-friendly, and need minimum sample preparation, which makes them effective instruments in a variety of situations, including research, law enforcement, and healthcare. On the whole, this paper highlights the versatility of PADs, emphasizing their role as adaptable platforms for drug testing within different matrices. Scientists and professionals can utilize these cutting-edge devices to improve the efficiency and accessibility of drug analysis.

Paper-based microfluidics has emerged as a promising field with diverse applications ranging from medical diagnostics to environmental monitoring. Despite significant progress in research and development, the translation of paper-based prototypes into practical end-user devices remains limited. This limitation stems from challenges related to devices not being sufficiently portable and autonomous, which paper-based microfluidics is expected to overcome. Yet for this purpose, we note the lack of comprehensive numerical modeling tools capable of simulating the intricate physicochemical phenomena involved in order to optimize the development process; hence, in this study, we introduce porousMicroTransport, a novel simulation package integrated with the open-source platform OpenFOAM®, designed to address these challenges. porousMicroTransport offers efficient solvers for fluid flow and transport phenomena in microfluidic porous media, including capillarity models and (bio)chemical reactions. Moreover, under horizontal flow conditions, porousMicroTransport application field can be extended to any porous media. We demonstrate the software’s effectiveness in two example cases, showcasing its ability to accurately reproduce complex phenomena involved in paper-based devices. By virtue of being an easy-to-use and computationally efficient tool, porousMicroTransport facilitates the design and optimization of devices, potentially enabling more devices to meet the WHO’s REASSURED criteria for point-of-care testing. We anticipate that this tool will accelerate the development and deployment of robust and portable diagnostic devices, bridging the gap between research and practical applications.

Objectives: Meningitis is a medical emergency, and it is crucial to diagnose it accurately and promptly in order to manage patients effectively. It would, therefore, be essential to introduce and have fast, accurate, and user-friendly methods to determine the cause of these infections. This study aimed to demonstrate a potentially cost-effective new approach for detecting meningitis using a paper-based vertical flow microarray, which could be useful in settings with limited resources. Methods: We describe a multiplex paper microarray for detecting Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae, and Salmonella spp. by the passive vertical flow of PCR-amplified clinical samples. A multibiotinylated amplicon was obtained as a product of PCR in the presence of both a biotinylated primer and biotin-11-dUTP. An enhancement step based on an enzyme-free gold enhancement protocol was also used to facilitate visual detection. Results: This study showed that the vertical flow microarray (previously evaluated for one pathogen) can discriminately detect the amplification results down to the 102 copies of DNA limit for four meningitis pathogens in a multiplexed set-up. The study further demonstrated the ability of this device and setup to detect three of the four pathogens from clinical biosamples. Discussion: This study demonstrated the capacity of a vertical flow microarray device to detect amplification products for four prevalent meningitis pathogens in a multiplex format. The vertical flow microarray demonstrated consistent visualization of the expected gene amplification results; however, indicating limitations in the pre- and amplification steps. This study highlights the potential of this multiplexing method for diagnosing meningitis and other syndromic diseases caused by various pathogens, especially in resource-limited areas.

The material of storage containers affects the shelf life and the chemical composition of food. Artisanal agave spirits, such as mezcal and bacanora, might be filled into low-cost plastic bottles that compromise product quality. We developed an analytical platform to identify the bottle materials of agave spirits, which employs 3D-printed cartridges, and the robotic platform Open LabBot/Open SprayBot for paper-spray ionization mass spectrometry (PS-MS). The bottle material of 102 fresh samples could be identified with a 2 % error. Samples stored for two years at −20 °C in glass vials still were classified correctly in 76 % of the cases. Therefore, the spirits still appear adulterated for a prolonged time after re-bottling into inert containers. The measurement time is about 30 s/sample. Thus, the 3D-PS-MS strategy can be applied for the high-throughput screening for bottle materials of agave spirits and other alcoholic beverages.

We used a microfluidic paper-based analytical device (μPAD) to investigate the influence that zinc reduction exerts on the determination of nitrite and nitrate ions in natural water samples. The μPAD consists of layered channels for the reduction of nitrate to nitrite with zinc powder and the subsequent detection of nitrite with Griess reagent. The amount of zinc, number of layers, and reaction time for the reduction were optimized to obtain an intense signal for nitrate. Initially, the sensitivity to nitrate corresponded to 55% that of nitrite, which implied an incomplete reduction. We found, however, that zinc decreased the sensitivity to nitrite in both the μPAD and spectrophotometry. The sensitivity to nitrite was decreased by 48% in spectrophotometry and 68% in the μPAD following the reaction with zinc. One of the reasons for the decreased sensitivity is attributed to the production of ammonia, as we elucidated that both nitrite and nitrate produced ammonia via the reaction with zinc. The results suggest that the total concentration of nitrite and nitrate must be corrected by constructing a calibration curve for nitrite with zinc, in addition to developing curves for nitrate with zinc and for nitrite without zinc. Using these calibration curves, the absorbance at different concentration ratios of nitrite and nitrate ions could be reproduced via calculation using the calibration curves with zinc for nitrite and nitrate. Eventually, the developed μPAD was applied to the determination of nitrite and nitrate ions in natural water samples, and the results were compared with those using a conventional spectrophotometric method. The results of the μPAD are in good agreement with those of conventional spectrophotometry, which suggests that the μPAD is reliable for the measurement of nitrite and nitrate ions in natural water samples.

Abstract This study aims to characterise the so-called Sialkoti paper used to produce Pahari drawings preserved today in the Wereldmuseum in Leiden (Netherlands) (WML). These works originate from the Punjab Hills in India (today Himachal Pradesh) and are commonly known as ‘Pahari miniature paintings’. The paper upon which these drawings are executed is said to have been produced in Sialkot during the eighteenth and nineteenth centuries when papermaking was an integral part of an overall regional economy correlated with other sectors such as agriculture and the textile industry. Although the term Sialkoti refers to identified papermills in Sialkot (now Pakistan), the paper from this region is yet to be subjected to a systematic study. This article therefore explores the paper(s) in question through macro- and microscopic observations of structure, pulp and fibres. The study of historical sources, complemented by the analysis of paper samples and fibre identification, has revealed that the pulp would have been prepared from a variety of manufactured products using different technologies, such as rags, cloth, mats, rope and other plant-based materials made from local bast fibres which, once tattered, were recycled to prepare the pulp. Microscopic study reveals that a variety of fibre combinations under different conditions and processing steps were used, in particular sunn hemp fibre (Crotalaria juncea L.), a plant species that has until now rarely been identified in historical paper. In addition, the presence of kenaf and jute fibres, as well as a significant quantity of cotton fibres, have also been demonstrated. To overcome the lack of comparative materials, our work was supported by a comparative study of several materials made from sunn hemp now held in the Ethnobotany Collection at Kew Gardens. Samples were taken from these materials and provided useful reference micrographs for the identification of the WML samples. The quality of the paper used by Pahari artists, as well as the raw materials available and their processing, are discussed in detail. Putting all the data, including technical and historical information into perspective, we conclude that the Pahari artists used a paper of inferior quality compared to other types of paper used for other purposes such as the creation of illuminated manuscripts in the Punjab plains. This study therefore provides useful analytical and material evidence that complements previous historical, technical and anthropological studies.

Abstract Paper bookbindings have been disregarded for centuries by scholars since they were only considered temporary covering materials for manuscripts and books. Recently, there is a willingness to reconsider these bindings and to evaluate their role. Thanks to the collaboration with the Marciana National Library in Venice, which stores an impressive collection of 849 detached bindings, the current research provides a chemical-physical elucidation about the composition and the manufacture of paper bookbindings realized between the 16th and the eighteenth century in the Venetian area. A selection of bookbindings was analysed by the means of complementary methods (thickness measurements, Attenuated Total Reflection—Fourier-Transform Infrared Spectroscopy (ATR-FTIR), Pyrolysis–Gas Chromatography–Mass Spectrometry (Py-GC–MS) and X-Ray Fluorescence (XRF)). Data evidence the presence of cellulose as the main component of paper pulp; hemicellulose and lignin were identified too, probably related to the presence of linen/hemp rags in the paper production. Gelatine was detected muck likely related to paper sizing; among inorganic additives CaCO3 was found in all samples. The presence of waxy material may be due to past undocumented conservation treatments.

Abstract Purpose Paper-based artifacts hold significant cultural and social values. However, paper is intrinsically fragile to microorganisms, such as mold, due to its cellulose composition, which can serve as a microorganisms’ nutrient source. Mold not only can damage papers’ structural integrity and pose significant challenges to conservation works but also may subject individuals attending the contaminated artifacts to health risks. Current approaches for strain identification usually require extensive training, prolonged time for analysis, expensive operation costs, and higher risks of secondary damage due to sampling. Thus, in current conservation practices with mold-contaminated artifacts, little pre-screening or strain identification was performed before mold removal, and the cleaning techniques are usually broad-spectrum rather than strain-specific. With deep learning showing promising applications across various domains, this study investigated the feasibility of using a convolutional neural network (CNN) for fast in-situ recognition and classification of mold on paper. Methods Molds were first non-invasively sampled from ancient Xuan Paper-based Chinese books from the Qing and Ming dynasties. Strains were identified using molecular biology methods and the four most prevalent strains were inoculated on Xuan paper to create mockups for image collection. Microscopic images of the molds as well as their stains situated on paper were collected using a compound microscope and commercial microscope lens for cell phone cameras, which were then used for training CNN models with a transfer learning scheme to perform the classification of mold. To enable involvement and contribution from the research community, a web interface that actuates the process while providing interactive features for users to learn about the information of the classified strain was constructed. Moreover, a feedback functionality in the web interface was embedded for catching potential classification errors, adding additional training images, or introducing new strains, all to refine the generalizability and robustness of the model. Results & Conclusion In the study, we have constructed a suite of high-confidence classification CNN models for the diagnostic process for mold contamination in conservation. At the same time, a web interface was constructed that allows recurrently refining the model with human feedback through engaging the research community. Overall, the proposed framework opens new avenues for effective and timely identification of mold, thus enabling proactive and targeted mold remediation strategies in conservation.

Abstract In the process of conservation mounting, starch paste made from wheat flour is the glue of choice to paste reinforcing strips and backing papers, often Xuan paper, for mending and decorating aged and damaged paper-based Chinese artworks. To keep objects intact and select appropriate conservation materials, this research explored the applicability of near-infrared (NIR) spectroscopy coupled with multivariate analysis for the characterization of contemporary unsized Xuan paper with and without starch. In particular, partial least squares (PLS) regression was used to predict the degree of polymerization (DP) of the paper, i.e., one of the most important properties of paper materials, and principal component analysis (PCA) was used to detect starch and to distinguish between papers with different amounts of starch. Using 12 contemporary unsized Xuan papers, the NIR-PLS method for DP prediction was validated, and the best-performed model was generated using the logarithmic transformation of DP−1 as a response variable, with root mean square error of prediction (RMSEP) of DP 128. The NIR-PCA method was also found to be applicable to separate starch-free papers and papers treated with starch, and the results indicate that the higher the content of starch, the better PCA classification performs. This research provides supporting data for the non-destructive characterization of Xuan paper-based objects and differentiates between Xuan paper before and after treatment with starch.

Environmental toxic pollutants and pathogens that enter the ecosystem are major global issues. Detection of these toxic chemicals/pollutants and the diagnosis of a disease is a first step in efficiently controlling their contamination and spread, respectively. Various analytical techniques are available to detect and determine toxic chemicals/pathogens, including liquid chromatography, HPLC, mass spectroscopy, and enzyme-linked immunosorbent assays. However, these sensing strategies have some drawbacks such as tedious sample pretreatment and preparation, the requirement for skilled technicians, and dependence on large laboratory-based instruments. Alternatively, biosensors, especially paper-based sensors, could be used extensively and are a cost-effective alternative to conventional laboratory testing. They can improve accessibility to testing to identify chemicals and pollutants, especially in developing countries. Due to its low cost, abundance, easy disposal (by incineration, for example) and biocompatible nature, paper is considered a versatile material for the development of environmentally friendly electrochemical/optical (bio) sensor devices. This review presents an overview of sensing platforms constructed from paper, pointing out the main merits and demerits of paper-based sensing systems, their fabrication techniques, and the different optical/electrochemical detection techniques that they exploit.

This study develops a green and sustainable analytical method using cellulose paper sorptive extraction (CPSE) coupled with gas chromatography-mass spectrometry (GC–MS) to determine dextromethorphan, tramadol, clozapine, and zolpidem (Ambien) in urine. The method involves immersing five 1″ × 1″ cellulose papers in diluted urine (0.5 mL urine diluted to 10 mL) to adsorb the drugs at 250 rpm for 45 min, followed by desorption with 2 mL methanol at 200 rpm for 10 min and subsequent GC–MS analysis. Key parameters, including the number and size of filter papers, elution solvent type and volume, extraction and elution times and speeds, sample pH, and ionic strength, were extensively optimized. Validation according to SWGTOX guidelines demonstrated excellent linearity (0.05–1 µg mL-1, R² > 0.999), high precision (RSD < 11.1 %), and accuracy (85.1–113.6 %). Sensitivity was high, with LODs ranging from 0.010- 0.013 µg mL-1 and LOQs from 0.033 to 0.043 µg mL-1. The method was successfully applied to blind urine samples, confirming its practical utility in forensic toxicology. Greenness assessment using ComplexMoGAPI and practicality evaluation using Blue Applicability Grade Index (BAGI) yielded high scores (81 and 70), underscoring the method's environmental sustainability and fitness for purpose, positioning it as an eco-friendly alternative to conventional extraction methods.

Chloride (Cl−) is an anion widely distributed in nature. It is also an essential parameter to consider when assessing the water quality for ensuring drinking water safety, preventing infrastructure damage, mitigating environmental impact, identifying groundwater contamination. This work presents the first development of a diameter-based measurement paper sensor for chloride analysis using the reaction based on a Mohr's precipitation titration. The paper sensor that has a circular shape with 3-cm diameter was pre-coated with AgNO3 and CrO42− forming brown precipitates of the Ag2CrO4. The sensor was sealed using lamination films with 3-mm diameter hole-punched inlets on the top of the lamination film for sample delivery. To detect chloride, the sensor was simply immersed into the sample. The chloride solution flows into the central sample inlet and spreads radially to undergo the displacement reaction with Ag2CrO4 precipitate, forming AgCl white precipitate whose diameter proportional to the chloride that can be observed within 3 min. Concentration of AgNO3 used was found to impact the analytical figures of merit. The lower AgNO3 concentration yields lower limit of detection, narrower linear range but higher sensitivity. The sensor was applied for chloride analysis in tap water, drinking water and industrial water and the chloride concentration obtained from the developed sensors are not significant differences from those obtained from the standard titration method at 95% confidence interval (two tailed P = 0.08) indicating that the developed sensor provides accurate analysis of chloride in water samples from various sources. The developed sensor was used by the untrained staffs for on-site of analysis chloride in tap water collected at 26 locations in SaenSuk Municipality area, Chonburi, Thailand. The results showed that the chloride level in all samples is in range of 52.2–84.7 mg L−1 which is far below the acceptable range set by the Provincial Waterwork Authority of Thailand (< 250 mg L−1) indicating that the tap water used in this area is safe for consumers.

Having economical, flexible, disposable and readily manufacturable devices for everyday sensing applications is of paramount importance. We report a novel and cost-effective technique for fabricating paper-based devices using an Advanced PAP (A-PAP) pen, which is capable of withstanding typical aqueous solutions and organic solvents. The quick fabrication process does not require any sophisticated instrumentation or a heating step, making it a promising technology for resource-limited settings. Using an A-PAP pen, we have fabricated two-dimensional (2D) paper-based devices for chemical detection of heavy metal and nitrite. We have also demonstrated the versatility of fabrication technique for biological sensing using 2D lateral flow paper-based devices for the detection of dopamine. Furthermore, the technique is also validated for fabricating complex three-dimensional (3D) paper-based devices using a paper origami technique for heavy metals sensing. The ready-to-use devices can be fabricated in seconds, making them convenient for on-the-spot testing. Overall, this technique provides a valuable tool for creating affordable, efficient, and accessible chemical and biological testing solutions.

Abstract Gels prepared from the polysaccharide gellan are used for aqueous poulticing treatments in paper conservation when the application of water must be restricted. Optimal use of the rigid, yet shapeable gel requires direct contact with the paper surface, which carries the risk of gel residues on the treated surface. We used acid methanolysis as a destructive analytical method to detect rhamnose as a component of gellan, which was undetectable with ATR-FTIR spectroscopy. We show that there is a significant probability of leaving gellan residues on the paper. Conservators should be aware of this potential side effect when considering the use of gellan poultices in direct contact with paper objects.

A novel design and set up of paper chromatography in the form of radial serpentine arms laying horizontally is proposed. The consumption of mobile phase is reduced to be 1 mL or less as compared to the tens of mL typically used in the conventional set ups for ascending paper chromatography, without any change in the order of the separated components. Greenness measurement based on the ChlorTox value is approximately 25, when comparing to a conventional system that consumes 25 mL of mobile phase. A digital image of the chemical separation makes data analysis more feasible as the image can be kept, and hence, extending the time for data analysis. The Retention Factor (Rf) value from a serpentine shaped stationary phase can be calculated based on measurement of linear distances of the solvent front and those travelled by each component, and converting them to arclengths using the mathematical equation of a catenary wave that produces that particular design. Proof of concept is demonstrated by the separation of food dyes using a two solvent system, where a nonvolatile salt solution is followed by a volatile organic solvent mixture of alcohols and base. Relationships between concentration, color intensity (RGB values), and zone arclength are also demonstrated which indicate possibility of quantitative study on the serpentine design using digital image analysis.

This work presents, for the first time, an exploitation of an argentometric Mohr's method for iodide detection using diameter-based measurement on laminated paper-based analytical device (LPAD). Our LPAD is simplified fabricated with no required hydrophobic barrier for patterning a detection flow channel. In the absence of a flow channel, the liquid is imbibed radially into the filter paper outward from the small center inlet hole. This imbibition leads to the measurement of diameter after the formation of the precipitation product. For LPAD, a rectangular piece of Whatman filter paper is cut and positioned between a top laminating sheet, which has a hole punched for inlet, and a bottom laminating sheet. The central inlet hole enables access to the liquid on the paper. For iodide analysis, silver nitrate is dispensed first, followed by the iodide standard/sample. This process leads to the formation of pale-yellow silver iodide solids on the paper. The chromate indicator solution is subsequently loaded to the paper. The color of the chromate solution imparts a tint to the circular band of silver iodide solids, resulting in an intense yellow color. When the silver iodide precipitates are stained, the chromate solution typically serves as an indicator, chemically reacting to an excess silver nitrate solution moistened on paper. This reaction generates an outer reddish-brown ring of silver chromate. The distinct color contrast between the intense yellow (tinted silver iodide) and reddish-brown (silver chromate) allows for clear observation of the measurement boundary, facilitating diameter-based measurements of the circular band of silver iodide. We demonstrate the applicability in analysis of pharmaceutical KI tablets. The quantitative results obtained from diameter-based measurement LPAD show good agreement with those obtained from the potentiometric method. Our hydrophobic barrier-free LPAD is rapid, cost-effective, low liquid consumption and applicable for onsite analysis.

The presence of pharmaceuticals in water is a major problem worldwide. To alleviate this, this study produced carbon blends from avocado seeds and paper waste and activated them with hydrogen peroxide (H2O2), nitric acid (HNO3) and potassium permanganate (KMnO4). The effectiveness of the adsorbents was tested in removing ibuprofen (IBU) and paracetamol (PRC) from water. Characterization of the adsorbents by SEM, BET, FTIR and TGA revealed that the morphology was porous, with a large surface area and several functional groups bound to the surface. The concentration effect experiments showed that the uptake of IBU and PRC increased with an increasing initial concentration and that these data were consistent with the Freundlich model. The contact time effect showed that the uptake of PRC was rapid in the initial phase for all the adsorbents. However, the rate gradually slowed down and equilibrium was reached after 40 min for BCMN, 60 min for BCMH and BCMP and 120 min for BCM. IBU, on the other hand, showed that equilibrium was reached after 30 min for BCMN, BCMH and BCMP and after 120 min for BCM. These data complemented the PSOM. The model is based on chemisorption, where electrons are transferred and shared, and hydrogen bonding and π-π interactions. The △Ho value confirms that the sorption of IBU and PRC was endothermic. The △So was positive, indicating greater freedom at the solution interface during uptake.

Abstract Soot stain from diverse sources is the most common stain that stains historical paper documents found in libraries, museums, and storage facilities. It is believed to be one of the types of deterioration that arises from the contact between stains and paper sheets. Therefore, in the present work, the effectiveness of the synthesized hybrid nanogel consisting of carbopol and nanoparticles (NPs) of ZnO, TiO2, or Fe3O4, in low and high-viscosity forms, for eliminating soot stains from historical paper manuscripts was conducted. The prepared hybrid nanogels were characterized utilizing the TEM, AFM, XRD, DLS, and Zeta Potential techniques. Following preparation, the soot-stained paper samples were heated to 105 °C for 6 days, a process known as accelerated thermal aging. Surface morphology, mechanical properties and the color change of the paper samples were investigated. The prepared hybrid nanogel had a spherical shape with well-defined edges and uniform size, with an average particle diameter ranging from 30 to 35 nm. There was no significant NPs agglomeration seen, suggesting uniform dispersion in the carbopol matrix. Additionally, the prepared gels' crystal structure and phase purity were revealed by the XRD analysis results. Paper fibers were visible in some parts of the treated sample with TiO2/carbopol hybrid nanogel at high-viscosity before aging. Cleaning soot-stained paper samples using high-viscosity Fe3O4/carbopol hybrid nanogel is more successful than using low-viscosity nanogel. the sample treated with high-viscosity ZnONPs/carbopol hybrid nanogel produced the highest total color differences (ΔE) (26.17). The paper sample treated with high-viscosity ZnO/carbopol hybrid nanogel exhibited the maximum tensile strength (61.8 N/mm2) and elongation at break (1.174%). The evaluation of the paper samples both before and after the cleaning process revealed that, the treatment with high-viscosity ZnO/carbopol hybrid nanogel gave the best results in removing soot stains from stained paper samples.

Abstract Numerous natural dyes were used to dye mediaeval Islamic paper from the tenth to the nineteenth century, using a variety of techniques. The objective of this research is to develop an analytical method using high performance liquid chromatography with diode array detection (HPLC–DAD) to identify natural dyes in forty historical Islamic paper manuscripts from two collections. In addition, novel information was obtained from original treatises containing recipes for dyeing paper and the chronological use of dyes in dyeing mediaeval Islamic paper between the tenth and seventeenth centuries. The results show that thirty-four of the forty manuscripts examined contained dyes. Six natural dyes were detected, including henna, madder, lac, safflower, turmeric, and weld. This is the first study aimed at developing a method for determining various natural dyes in Islamic paper from a wide historical and geographical range in the mediaeval time and to fill significant gaps in the technical and historical knowledge of papermaking.

Abstract Some ancient Chinese paper artifacts dyed with amur cork tree bark extracts are currently preserved to different extents in museums and libraries worldwide. As traditional natural plant dyes, the long-term performance of the amur cork tree bark extract-dyed handmade paper has been questioned under a preserved environment. The photodegradation process of the extract-dyed papers was examined under accelerating artificial UVA irradiation conditions according to China national standard-paper and board- accelerated aging (exposure to light). Changes during aging were analyzed by optical observation and scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectrometry (FTIR), pH, and tensile strength and folding endurance tests. The results showed that the main components from extracted dyes played an important role in affecting the photodegradation properties of dyed paper. The changes in surface color, pH, morphology and mechanical properties after the artificial UVA accelerated degradation tests revealed that a suitable concentration of the extract dyes for maintaining the long-term irradiation stability of the paper is important.

Abstract Efficient removal of mold stains becomes an important research topic for paper conservation. In this study, a cleaning scheme based on the combination of bioenzymes and biosurfactants was explored. Morphological and molecular biology identifications were first jointly applied to identify the dominant strains sampled from five ancient books that are stored in the same environment. Cellulolytic experiments were then conducted to evaluate the cellulose degradation ability of the strains according to the cellulolytic digestive index. Finally, paper Mockups for the ancient books were constructed to investigate the most effective combination of bioenzymes and biosurfactants in removing mold stains as well as its effect on the paper’s physical properties. The result concluded that the combination of 3% papain, 7% of sophorolipid or 7% of betaine, and distilled water, achieved optimal stain removal effect with over 50% cleaning rate at 35 °C, after 30 min of infiltration. The maximum color difference of the paper material after cleaning was around 0.60, pH was between 7.45 and 7.79, and no significant changes in tensile strength were observed. At the same time, Sophorolipid and Betaine both have superior deacidification, anti-acidification, anti-aging, and reinforcement capabilities, which can provide extra support to the fibrous structure in addition to cleaning the paper materials. The microbial contamination cleaning agent proposed in this study shows promising application prospects in conserving mold-contaminated paper artifacts.

Abstract The objective of this study was to identify the manufacturer of Hanji, Korean handmade paper widely used in conservation science. To achieve this, machine learning models utilizing attenuated total reflectance–infrared spectroscopy (ATR–IR) were developed to assess the robustness and effectiveness of the computed models. Principal component analysis (PCA), partial least squares–discriminant analysis (PLS–DA), decision tree (DT), and k-NN models were constructed using IR spectral data, with the spectral region between 1800 and 1500 cm⁻1 identified as the critical input variable through Variable Importance in Projection (VIP) scores. The transformation of the obtained spectra into second derivative spectra proved beneficial in this key spectral region, leading to significant improvements in model performance. Additionally, the application of DBSCAN for outlier detection was effective in refining the dataset, further enhancing the performance of the models. Specifically, the k-NN model, when applied to the selected variables and preprocessed with the second derivative transformation, achieved an F1 score of 0.92. These findings underscore the importance of focusing on the 1800–1500 cm⁻1 spectral range and applying outlier detection techniques, such as DBSCAN, to enhance the robustness and accuracy of the Hanji classification models by eliminating the influence of atypical data points.

Tin contamination in waters due to mining and natural activities in high concentrations can threaten human health. This research presents the development of a sensitive and selective colorimetric sensor in aqueous, paper, and gel-based to detect Sn2+. The development of such sensors is promising, with attractive advantages such as intense color, fast naked-eye response, and simple continuous fabrication. The addition of Sn2+ ions will change the color of the medium because curcumin (Cur) interacts with Sn2+, causing a decrease in free Cur, silver nanoparticles (AgNPs) becoming less stable, and a change in particle size. Colorimetric changes in Sn2+ were achieved by visual inspection within 10 min for aqueous-based and 20 min for paper and gel-based. The good linear relationship (R2 = 0.9999) between Sn2+ and Δ absorption with a detection limit of up to 66.99 µg/L. This method is relatively scalable in determining Sn2+ and shows good recovery between 80 and 105 %. This colorimetric sensor gives good sensitivity to Sn2+ metal ions which is expected to become the basic technology for developing in-situ sensors to monitor Sn2+ levels in tin industrial waste.

Abstract There are many paper manuscripts at museums, stores, and libraries that have different stains. The dust stains and soil remains played an important role in the degradation of these manuscripts. Therefore, the cleaning process for these stains is important to process. Unfortunately, the removal of stains by some traditional techniques can be hazardous to the paper's fibers. Therefore, this study aims to evaluate innovative nanoparticle gels in the cleaning process of dust stains from paper manuscripts. The synthesized nanomaterials [Fe3O4, TiO2, and ZnO]/Carbopol hybrid nanogel were examined in order to investigate the surface morphology, determine the physio-chemical properties, for phase structure, using scanning electron microscope (SEM), transmission electron microscope (TEM), AFM, DLS, XRD, and Zeta potential. Some stained paper samples were prepared and exposed to accelerated thermal aging at 100 °C for 72 h. The evaluation of the cleaning by nanogel was performed by different analytical procedures containing investigation with a USB digital microscope, SEM, color change, mechanical properties, and ATR-FTIR analysis. The results of this study showed that ZnO/Carbopol hybrid nanogel at high viscosity gave the best results in the cleaning process of mud stains through the ability to dismantle mud particles and increase surface contact with the solvent. The aged treated sample with high viscosity form of ZnO NPs/carbopol hybrid nanogel gave the highest tensile strength value of (56.0 N). The treated samples with the high viscosity form of ZnO NPs/carbopol hybrid nanogel gave the highest value of elongation (1.398%) before aging. It also does not affect the chemical composition of the paper after cleaning it, but rather on the whole, it bites the hydration of the paper, which positively affects the properties of the treated paper.

Abstract Traditional papermaking was a significant innovation that intrigued the information-sharing society in a wide range of the globe. The importance of finding the historical background hidden behind the historical traditional paper is critical to understanding societies in history. Advanced molecular biological research is applied to many forensic studies to identify the origin and criminal events. Yet, biological research refrained from the heritage science of traditional papers due to its damage to the samples. The current study explores the Pearson correlation between DNA in traditional paper and non-destructive measurement of characteristics of traditional paper. DNA concentration and purity were found to have a proportional relationship based on the CIEL*a*b* color system. The color of the traditional paper was assessed assessment shows green and yellow rather than red and blue. The DNA concentration demonstrated a positive linear correlation with the peaks of 992 cm−1, 1599 cm−1, and 1628 to 1638 cm−1 region, which were lignin-specific functional groups. The presence of lignin in traditional paper defines the colors green and yellow, which is related to the presence of a cell wall. The quantity of cell walls present is linked to DNA survival during the traditional papermaking process. Furthermore, the partial least square (PLS) regression model is established. The prediction model based on DNA, paper properties, and smoothing + the second derivative preprocessed attenuated total reflection-Fourier-transform infrared (ATR-FTIR) spectral data demonstrated valid purity predictions. The evaluation parameter of the cross-validated prediction model contains a low Root Mean Square Error of Cross-Validation (RMSECV) of 0.091 for DNA purity. The determination coefficient was close to 1. However, the further establishment of a validated DNA extraction methodology is required for the consistency of the prediction model for DNA concentration. The hierarchical clustering analysis demonstrated the agglomerative dendrogram on traditional paper samples. For the dendrogram, the Nasu paper mulberry (originating in northern Japan) was distinguished from another paper mulberry (originating in southwestern Japan) by clustering. By multivariate statistical analysis, the DNA presence and quality were predictable from the Japanese traditional papers. In addition, the clustering analysis provided the possible origin of paper mulberry materials for traditional papers. Based on the preliminary information, the need for DNA analysis on historical traditional paper can be determined.

Abstract Medieval paper, a handmade product, is made with a mould which leaves an indelible imprint on the sheet of paper. This imprint includes chain lines, laid lines and watermarks which are often visible on the sheet. Extracting these features allows the identification of the paper stock and gives information about the chronology, localisation and movement of manuscripts and people. Most computational work for feature extraction of paper analysis has so far focused on radiography or transmitted light images. While these imaging methods provide clear visualisation of the features of interest, they are expensive and time consuming in their acquisition and not feasible for smaller institutions. However, reflected light images of medieval paper manuscripts are abundant and possibly cheaper in their acquisition. In this paper, we propose algorithms to detect and extract the laid and chain lines from reflected light images. We tackle the main drawback of reflected light images, that is, the low contrast attenuation of chain and laid lines and intensity jumps due to noise and degradation, by employing the spectral total variation decomposition and develop methods for subsequent chain and laid line extraction. Our results clearly demonstrate the feasibility of using reflected light images in paper analysis. This work enables feature extraction for paper manuscripts that have otherwise not been analysed due to a lack of appropriate images. We also open the door for paper stock identification at scale.

Chemical wastes, such as synthetic dyes and coloring agents, pose significant concerns due to their detrimental impact on human health and ecosystems. As an eco-friendly alternative, the study of natural dyes and coloring agents has gained momentum over the last decade, owing to their biodegradability and reduced environmental and health risks. Here, we report a novel approach employing a butterfly pea anthocyanin paper-based sensor to quantify Fe(III) ions in water. Compared to previous green sensing techniques reliant on heavy instrumentations, this approach offers enhanced accessibility, cost-effectiveness, and user-friendliness. Notably, this study is the first example of natural dye sensing on a capillary microfluidics system. The capillary-driven microfluidic system ensures user-friendly operation and allows the sensing platform to be directly immersed in water without reagent loss. The device's design involves drying the butterfly pea-derived anthocyanin reagent within a pH-controlled paper substrate embedded in the capillary-driven microfluidic system. Smartphone-based colorimetric signal generation and quantification was achieved within seconds for a working range of 50–800 mg/L, with the device's detection limit of 43 mg/L using ImageJ and 55 mg/L using the smartphone app. This green sensing methodology has the potential to be used for groundwater sources with elevated Fe(III) levels. Additionally, this platform can be used in chemistry educational settings as an effective means to understand fundamental concepts such as acid-base reactions, base strength, ionic equilibrium, and metal complexation in a user-friendly microfluidic system.

Abstract Microorganisms, especially microscopic filamentous fungi, represent one of the most significant factors influencing the degradation of cultural heritage cellulosic objects. Early detection, identification and characterisation of microbial communities can help select a suitable conservation intervention and, in addition, allow possible control of its effectiveness. A combination of spectral methods and statistical data processing appears to be a suitable alternative to conventional methods for monitoring microbial contamination. The main goal of the presented research was the investigation of the spectral properties of vital and devitalised filamentous fungi Alternaria alternata, Aspergillus niger, Cladosporium herbarum, Penicillium chrysogenum, and Trichoderma atroviride, inoculated on a paper substrate Whatman in two phases—dormant (conidia) and active (mycelium). The combination of the UV-Vis-NIR and NIR Fibre Optics Reflection Spectroscopy (FORS) with the Principal Component Analysis (PCA) was set to determine whether the spectra of vital and devitalised forms of studied samples differ. The obtained results prove differences between the spectra of vital and devitalised forms of filamentous fungi, at least in one studied spectral region. Therefore, UV-Vis-NIR and NIR FORS combined with PCA seems to be a promising tool for monitoring paper-based objects' microbial contamination.

Abstract Presence of copying pencils in heritage objects poses a significant challenge for conservators due to their proneness to fading, sensitivity to solvents and difficulties in differentiation from regular graphite pencils. In this paper a method of copying pencils identification by means of ATR—FTIR spectroscopy is used. A protocol for spectra processing and dimensionality reduction of spectral data by means of principal component analysis has been developed, allowing for pencil types differentiation and providing an easy to read visual representation of the collected data. The protocol has been developed on mock-up samples and tested on objects from the archives of the State Museum Auschwitz – Birkenau.

Contamination of trace levels of volatile organic compounds (VOCs) in enclosed spaces is not usually a significant cause for concern; however, it can be relevant in the case of canine scent detection training as a canine’s superior sense of smell makes them highly likely to detect low levels of contamination, contributing to inefficient training. Thus, herein, we address the need for a simple, low-cost, robust, vapochromic sensor to determine the cross-contamination of VOCs within closed containers, such as canine training aid kits. This study focuses on the development of a vapor sensor, which produces a rapid colorimetric change when a target chemical vapor is present. A pH indicator is used as the colorimetric dye and its incorporation into a sol–gel matrix on a paper substrate is confirmed via SEM characterization. The sensor’s stability and performance is tested against exposure to various levels of sunlight and temperature. The design allows the sensor to present a clear and unambiguous visible response to the release of the volatile target within a closed container. It can be readily incorporated into existing training kits and functions as a straightforward reminder of when training aids need to be changed or a new containment system should be considered.

Loop-mediated isothermal amplification (LAMP) has been widely used to detect many infectious diseases. However, minor inconveniences during the steps of adding reaction ingredients and lack of simple color results hinder point-of-care detection. We therefore invented a fluorometric paper-based LAMP by incorporating LAMP reagents, including a biotinylated primer, onto a cellulose membrane paper, with a simple DNA fluorescent dye incubation that demonstrated rapid and accurate results parallel to quantitative polymerase chain reaction (qPCR) methods. This technology allows for instant paper strip detection of methicillin-resistant Staphylococcus aureus (MRSA) in the laboratory and clinical samples. MRSA represents a major public health problem as it can cause infections in different parts of the human body and yet is resistant to commonly used antibiotics. In this study, we optimized LAMP reaction ingredients and incubation conditions following a central composite design (CCD) that yielded the shortest reaction time with high sensitivity. These CCD components and conditions were used to construct the paper-based LAMP reaction by immobilizing the biotinylated primer and the rest of the LAMP reagents to produce the ready-to-use MRSA diagnostic device. Our paper-based LAMP device could detect as low as 10 ag (equivalent to 1 copy) of the MRSA gene mecA within 36-43 min, was evaluated using both laboratory (individual cultures of MRSA and non-MRSA bacteria) and clinical blood samples to be 100% specific and sensitive compared to qPCR results, and had 35 day stability under 25 °C storage. Furthermore, the color readout allows for quantitation of MRSA copies. Hence, this device is applicable for point-of-care MRSA detection.

Many neonates’ manifest hyperbilirubinemia and jaundice during the first week following birth because of bilirubin accumulation in the blood. Newborns with severe hyperbilirubinemia develop neurotoxicity. Therefore, sensitive, accurate, cost-effective, and timely determination of bilirubin levels is highly desired. Herein, we present three simple systems of bilirubin assessment based on spectrophotometric, and digital imaging tools. Image-capturing devices pose a formidable challenge to sophisticated spectrophotometers and field-monitoring devices because of their simplicity and sensitivity. The first and second systems of bilirubin assessment, in solution, relied on spectrophotometric and conventional color responses of digital images collected with conventional or android smartphone camera, with LODs of 0.060–0.082 and LOQs of 0.200–0.273 ppm bilirubin. The third system utilized a microfluidic paper-based analytical device (μ-PAD) that is patterned with a wax printer on Whatman grade-1 chromatographic papers, with linear calibration graphs of up to 2.70,s and LODs of 0.035–0.040 and LOQs of 0.117–0.133 μg bilirubin/μ-PAD.

One-pot syntheses and in situ ultrasonication have been optimized to generate tunable and highly hydrophobic 2,7-octadienyl-ether (ODE) cellulose nanofibrils (CNFs). Using only butadiene sulfone to serve as dual reaction medium and precursor to 1,3-butadiene (1,3-BD) for telomerization with cellulose hydroxyls, the OH-to-ODE conversion significantly improved from ca. 0.7 to 1.2, 1.8, 3.1, and 4.1 mmol of ODE/g-cellulose at 103-110 °C for 1-2 h. Ultrasonication was highly effective and versatile in the direct disintegration of ODE-cellulose (ODE-cell) in nonpolar organic solvents and plant oils into ODE-CNFs as well as pretreating cellulose for improved functionalization. Mixing 2 wt % in situ ultrasonicated 1.2 mmol of ODE/g-cell improved the modulus of polybutadiene six times and the strength of poly(styrene-b-isoprene-b-styrene) three times, whereas in situ ultrasonication of 1.8 mmol/g-cell directly with linseed oil at merely 0.07 wt % created holistic biobased hydrophobic cellulose paper to resist water penetration while also significantly improving the tensile strength. This optimized telomerization and streamlined in situ ultrasonication approach has presented a sustainable synthesis and processing strategy to generate highly hydrocarbon-compatible nanocelluloses previously unattainable.

In the present article we report a new hybrid microfluidic device (hyFlow) comprising a disposable paper electrode and a three-dimensional (3D) printed plastic chip for the electrochemical detection of a magnetic bead-silver nanoparticle (MB-AgNP) bioconjugate. This hybrid device evolved due to the difficulty of incorporating micron-scale MBs into paper-only fluidic devices. Specifically, paper fluidic devices can entrap MB-containing conjugates within their cellulose or nitrocellulose fiber matrix. The hyFlow system was designed to minimize such issues and transport MB conjugates more efficiently to the electrochemical detection zone of the device. The hyFlow system retains the benefit of fluid transport by pressure-driven flow, however, no pump is required for its operation. The hyFlow device is capable of detecting either pre-formed MB-AgNP conjugates or conjugates formed in situ. The detection limit of AgNPs using this device is 12 pM, which represents just 22 AgNPs per MB.

The development of highly specific biomimetic recognition material is a challenge for rapid detection of harmful residues in foodstuff. In this study, a paper-based boronate affinity metal-organic framework/molecularly imprinted polymer microfluidic chip (FZS-BA@MIP) was constructed based on the in situ construction strategy, which was also designed as a highly specific biomimetic recognition module. Here, the homogeneous zeolitic imidazole framework-8 (ZIF-8) membrane served as a great scaffold and enrichment layer. Besides, the recognition layer of MIP was prepared based on a highly oriented boronate affinity surface imprinting strategy. With the aid of the liquid flow channel, the highly specific enrichment and visual detection for antibiotic residues like kanamycin in actual products were achieved on the paper chip module of an integrated lateral flow platform. The whole analysis process could be accomplished within 30 min. In brief, this study offered a new integrated biomimetic recognition platform for visually detecting harmful veterinary residues containing cis-diols, which demonstrated promising commercial value in point-of-care testing of foodborne hazardous compounds.

Abstract In paper degradation studies, the viscosity-average degree of polymerisation (DPv) is often used as a key indicator of the extent of degradation of cellulosic paper. DPv can be deduced from the viscosity of dilute paper solutions, as typically measured through glass capillary viscometry. The current study proposes an efficient, alternative method to evaluate DPv of cellulosic paper, which is based on rotational rheometry. The proposed methodology relies on the application of a shear flow in a thin film of cellulose solution to measure its dynamic viscosity, from which DPv can be subsequently derived in a straightforward fashion. Rheometry allows to measure the viscosity for a range of shear rates, which results in multiple DPv evaluations per sample, and thus in statistically representative data from an individual test. Further, rheometry typically requires considerably less paper mass per test than glass capillary viscometry, which makes the method attractive for paper degradation studies with limited sample availability. Also, rheometry measurements are less work-intensive than glass capillary viscometry measurements. The rheometry method has been applied to 4 hygrothermally aged cellulose paper samples and the unaged counterpart. The measurement results regarding the age-dependency of DPv and the number of cellulose chain scissions are compared to those obtained by glass capillary viscometry, showing a very good agreement. At a longer ageing time, both experimental methods reveal a non-linear decrease in time of DPv, and a non-linear increase in time of the number of cellulose chain scissions, which indicate that the cellulose ageing process is realistically captured. The agreement in measurement results further demonstrates that rheometry is an easy-to-use, accurate and efficient alternative for DPv measurements by glass capillary viscometry.

Oxygen (O2) was discovered approximately 250 years ago (Contribution 1), a breakthrough accredited to at least three people: Antoine-Laurent de Lavoisier in France (Antoine Lavoisier), Carl Wilhelm Scheele in Sweden, and Joseph Priestley in England [...]

Condition assessment of works of art created with oil media on paper could be a complex matter when presenting problems of damage due to the absorption of oil binders by the paper support, since they depend on several factors and occur in variable conditions. The present work refers to the results of an investigation on the effect of linseed oils on the color, opacity, morphology, tensile strength, and chemical properties of lignocellulosic papers, in comparison to that of pure cellulosic papers. Lignocellulosic papers are involved in research on new, yet significant, parameters that might influence the behavior of the oil-impregnated areas of the supports upon aging. The research was applied to mock-ups, made of two types of lignocellulosic paper impregnated with three types of linseed oil and subjected to accelaratated ageing in specific conditions of relative humidity and temperature in closed environment. The research involved colorimetry, opacity, tensile strength, pH measurements, SEM, FTIR, and VOC analysis with GC-MS. The results indicated that thermal-humid ageing caused the gradual darkening of the oil-impregnated mock-ups, alterations in opacity, and decrease of pH values, depending mainly on the formulation of linseed oil, as well as a reduction in tensile strength. FTIR analysis results indicated that the chemical changes that occur upon ageing supported the recorded optical and mechanical alterations, while VOC emissions are both associated with the paper type and the kinetics of degradation of the different types of linseed oil.

The goal of green chemistry is to reduce the impact of chemical processes on the environment. In this context, it is important to develop new analytical tools that comply with the principles of green analytical chemistry (GAC) to contribute to the sustainable development of the planet. This study describes the development of an environmentally friendly methodology using paper-based analytical devices (µPADs) to perform acid-base titrations by distance-based measurements. The devices were composed of a circular zone defined with 5 mm diameter connected to a rectangular channel of 40 mm long × 3 mm wide. The titrations of acidic (strong and weak) and alkaline (strong and weak) solutions were successfully demonstrated using 10 µL of titrant solution and 10 µL of sample solution. The solution added into the zone travels different distances depending on the concentration of the titrated, thus promoting the channel coloration or discoloration. The distance measurements covered by the titrated solutions were obtained recorded with a digital caliper. As proof-of-concept for quantitative purposes, the µPAD was then used to determine the acetic acid content in commercial vinegar. The average distances ranged from to 32.0 to 32.5 mm and the concentration values ranged from 4.3 to 4.6% (m/v). Conventional acid-base volumetry was used as a control method, and the obtained results demonstrated no statistical difference at 95% confidence level. Lastly, the 12 principles of GAC were analyzed to evaluate the suitability of the proposed method. Considering a unified scale between 0 and 1, the final green value was 0.72. Titrations with distance-based detection on µPADs were found to be a technique with fast responses and low cost that can be used as a replacement for conventional practices in teaching laboratories or adapted for the detection of different analytes.

Oil media on paper, such as oil paintings, sketches, prints, and books, occasionally present problems associated with the effect of oil medium on the paper support, raising a composite matter of condition assessment as it depends on several factors. The present work examines the effect of linseed oil on paper and, in particular, the changes caused by three types of linseed oil on the optical, morphological, mechanical, and chemical properties of pure cellulosic paper, employing mock-ups submitted to artificial ageing in controlled conditions of relative humidity and temperature in airtight vessels. The study involved colorimetry, opacity, tensile strength, pH measurements, SEM, FTIR, and VOC analysis with GC-MS. Processing of the results has so far indicated that thermal-humid ageing caused the gradual darkening of the oil-impregnated mock-ups, as well as alterations in opacity, intense fall of pH values, and severe reductions in tensile strength, while linseed oil processing during manufacture has a significant impact. FTIR spectra have indicated that chemical changes upon ageing are in accordance with those of optical and mechanical changes, while VOC emissions are mostly associated with the drying and degradation of the different types of linseed oil.

Abstract Extracts from amur cork tree barks contain some of the most important traditional natural dyes used, especially for functional production in ancient Chinese papers, due to religious reasons and their aesthetic aspects and antibacterial properties. Some ancient paper artefacts, dyed with this colourant and scattered around the world, are currently preserved to different extents. This study aims to characterize the thermal degradation process of amur cork tree bark extracts dyed papers to improve the knowledge and effectiveness of restoration practices. The properties of extracts dyed papers treated under dry-heat accelerating ageing conditions were investigated via optical observation and scanning electron microscopy as well as with pH, tensile strength and folding endurance analyses. The results showed that the main components from extracted dyes played important roles in affecting the properties of dyed paper. The changes in surface colour, pH, morphology and mechanical properties after the artificial dry-heat ageing tests revealed the most suitable concentration of extract dyes for maintaining the long-term thermal stability of the paper.

Abstract The Alessandrina Library was founded in 1667 by pope Alexander VII Chigi and is nowadays housed in the Campus of Sapienza University of Rome (Italy). Within its Ancient (mostly made of rag paper) and Modern (mostly made of contemporary paper) collections, it includes more than one million books produced from the XVI to the XXI century. In 2019, six thermo-hygrometers were deployed in its multi-storey repository to monitor temperature (T) and relative humidity (RH). Hourly T and RH data collected over 2 years allowed us to evaluate spatial and temporal thermo-hygrometric distributions and to carry out a comprehensive assessment of the climate-induced risks (mechanical, chemical, and biological deterioration mechanisms). Vertical temperature gradients associated with unstable conditions occurred in winter, resulting in upraising air flows up to the ceiling. The risky short-term RH fluctuations (EN 15757:2010) were determined to avoid mechanical stress in case of loans, relocation, and consultation. The Time Weighted Expected Lifetime (TWEL) index was used to evaluate the chemical risk for different paper-based collections as a function of their acidity and degree of polymerisation, also considering the typical response time of paper books to T and RH changes. The TWEL calculation estimated that the durability of acidic paper was around 300 years and highlighted that rag paper could be subject to cellulose hydrolysis only in summer and autumn, while contemporary paper was mostly at no risk. The risk of mould germination (Sedlbauer diagram) was possible on few days in Autumn, while the production of insect eggs (Brimblecombe empirical function) was favoured during approximately 42% of time over the year. In addition, illuminance and colorimetric measurements (performed on selected book covers) showed that light-sensitive objects could be exposed to the photodeterioration risk in the east-facing side of the repository. Although the investigation focussed on a specific case study, a similar approach could be effectively adapted to most library and archival repositories conserving paper-based collections.

Forensic document examination has been considered one of the most important fields in the forensic science. For this, a quick, effective, and cheap techniques for evaluation of forensic evidence is highly required. This study explores the comparison of A4 document paper by chemical and physical analysis. 16 of white A4 paper from different brands were analyzed by FTIR for investigation of structural characteristics. Video Spectral Comparator 8000 has been used to compare the A4 papers under different light source. The inorganic filler composition in the paper is also explored by ICP‐OES. The calcium carbonate content in document papers play a discriminant role which found to be between 16.02 % and 35.54 %. Also, water contact angle has been utilized in order to examine the surface of paper which is generally related to the inorganic filler and other additives. The WCA results ranged between 83° and 111° that enable quick and easy way to compare A4 document papers. The experimental results have demonstrated that besides FTIR methods, other methods such as ICP‐OES for elemental composition, WCA for wetting test, VSC for visualization under different light of source could have been applied for comparison of document papers in case of criminal cases. [ABSTRACT FROM AUTHOR]

Abstract This study applied various scientific analyses to one fragment of paper and three pigments excavated from earthenware found in the Hoeamsa Temple site at Yangju, Korea, which is believed to have been built in the early twelfth century. Radiocarbon dating of the paper fragment suggests a manufacture date between 1460 and 1646 (at a 95% confidence interval). It was estimated to have been used during the early and middle period of the Joseon dynasty (1391–1776), when the Hoeamsa Temple site was rebuilt. In addition, by staining the fiber of the paper fragment with Graff “C” stain, the paper’s raw material was identified as paper mulberry through dislocation, cross-marking, and transparent membrane, which are characteristics of the bast fiber. Efforts were made to identify their material properties and manufacturing techniques of the three types of pigments. Color difference analysis was performed by distributing the pigments in large areas to reveal characteristic differences according to the color difference of the pigment. We found that green-type pigments are malachite and atacamite, red-type pigments are hematite based on the element Fe, and white-type pigments are quartz and muscovite based on the elements Si and Al. In addition, as the size distribution of the three types of pigments is wide and has a multi-peak distribution curve, it was concluded that the pigments were used without purification.

In the era of liquid biopsy, microRNAs emerge as promising candidates for the early diagnosis and prognosis of cancer, offering valuable insights into the disease's development. Among all the existing analytical approaches, even if traditional approaches such as the nucleic acid amplification ones have the advantages to be highly sensitive, they cannot be used at the point-of-care, while sensors might be poorly sensitive despite their portability. In order to improve the analytical performance of existing electroanalytical systems, we demonstrate how a simple chromatographic paper-based disk might be useful to rationally improve the sensitivity, depending on the number of preconcentration cycles. A paper-based electrochemical platform for miRNA detection has been developed by modifying a paper-based electrode with a methylene blue (MB)-modified single-stranded sequence (ssDNA) complementary to the chosen miRNA, namely miR-224 that is associated with lung cancer. A detection limit of ca. 0.6 nM has been obtained in spiked human serum samples. To further enhance the sensitivity, an external chromatographic wax-patterned paper-based disk has been adopted to preconcentrate the sample, and this has been demonstrated both in standard and in serum solutions. For each solution, three miR-224 levels have been preconcentrated, obtaining a satisfactory lowering detection limit of ca. 50 pM using a simple and sustainable procedure. This approach opens wide possibilities in the field of analytical and bioanalytical chemistry, being useful not only for electrochemistry but also for other architectures of detection and transduction. [ABSTRACT FROM AUTHOR]