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Rapid and accurate identification of bacteria is essential to ensure food safety and prevent pathogenic bacterial infection. In this study, a highly efficient method was established for accurately identifying bacterial species by applying Ag NP-filter paper based Surface enhanced Raman spectroscopy (SERS) analysis and Partial Least Squares-Discriminant Analysis (PLS-DA) statistical methods. The flexible Ag NP filter paper substrate with high sensitivity and uniformity was prepared by a facile and low-cost silver mirror reaction at room temperature, which exhibited desirable SERS activity in bacteria detection. Furthermore, PLS-DA was successfully employed to distinguish SERS spectra from S. aureus CMCC 26003, E. faecalis ATCC29212 and L. monocytogenes ATCC 19115 with a sensitivity of 93.3-100%, specificity of 96.7-97%, and overall predicting accuracy of 95.8%. This exploratory study demonstrates that a Ag NP-filter paper based SERS sensor coupled with PLS-DA has great potential for rapid and effective detection and identification of bacteria., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Two-dimensional vertically aligned Bi 2 O 3 nanosheets over carbon paper (CP) were prepared via an in situ growth approach. Bi 2 O 3 /CP exhibits a robust photocatalytic activity, as well as renewability and flexibility. With Rhodamine B and 2,4-dichlorophenol used as target pollutants, the rate constant of Bi 2 O 3 /CP was 3.72 × 10 -3 min -1 and 6.93 × 10 -3 min -1 under visible-light irradiation for 2 h, respectively. The improved activity was attributed to the synergistic effects of the hierarchical structure of Bi 2 O 3 and the conductive substrate, CP; the former provided efficient catalytic sites for the pollutants and absorbed more of the light scattered among the nanosheets, while the latter is beneficial to the photogenerated electron transfer., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

In the present work, TiO 2 rutile nanorods and anatase nanoflakes have been grown on carbon fiber paper (CFP) by the hydrothermal method. Their photoelectrochemical properties and photocatalytic performances have been investigated. The introduction of CFP is found to improve visible light absorption intensity and effective surface areas apparently, and also make TiO 2 photocatalysts easier to recycle from aqueous waste. An ultrasonic field was employed during the process of photocatalysis. Sono-photocatalytic efficiency is found to be enhanced significantly in comparison with those of photocatalysis and sonocatalysis, which indicates a positive ultrasonic synergy effect. The scavenger experiments reveal that superoxide radicals (˙O 2 - ) and hydroxyl (˙OH) are the predominant active species during the dye degradation sono-photocatalytic process assisted by CFP-supported TiO 2 catalysts. To investigate the ultrasonic synergy photocatalytic effect, the generated amount of reactive oxygen species (ROS) was detected and quantitatively evaluated under visible light, ultrasound, and the combined condition of visible light and ultrasound. As a result, the present work provides an efficient way to improve photocatalytic performance and to realize easy recovery of photocatalyst, which will be helpful for better design of advanced photocatalysts for practical applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Arsenic (As) as a metal ion has long-term toxicity and its presence in water poses a serious threat to the environment and human health. So, rapid and accurate recognition of traces of As is of particular importance in environmental and natural resources. In this study, a fast and sensitive colorimetric method was developed using silver nano prisms (Ag NPrs), cysteine-capped Ag NPrs, and methionine-capped Ag NPrs for accurate detection of arsenic-based on transforming the morphology of silver nanoparticles (AgNPs). The generated Ag atoms from the redox reaction of silver nitrate and As(iii) were deposited on the surface of Ag NPrs and their morphology changed to a circle. The morphological changes resulted in a change in the color of the nanoparticles from blue to purple, which was detectable by the naked eye. The rate of change was proportional to the concentration of arsenic. The changes were also confirmed using UV-Vis absorption spectra and showed a linear relationship between the change in adsorption peak and the concentration of arsenic in the range of 0.0005 to 1 ppm with a lower limit of quantification (LLOQ) of 0.0005 ppm. The proposed probes were successfully used to determine the amount of As(iii) in human urine samples. In addition, modified microfluidic substrates were fabricated with Ag NPrs, Cys-capped Ag NPrs, and methionine-capped Ag NPrs nanoparticles that are capable of arsenic detection in the long-time and can be used in the development of on-site As(iii) detection kits. In addition, silver nanowires (AgNWs) were used as a probe to detect arsenic, but good results were not obtained in human urine specimens and paper microfluidic platforms. In this study, for the first time, AgNPs were developed for optical colorimetric detection of arsenic using paper-based microfluidics. Ag NPrs performed best in both optical and colorimetric techniques. Therefore, they can be a promising option for the development of sensitive, inexpensive, and portable tools in the environmental and biomedical diagnosis of As(iii)., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

This work presents a novel filter paper-based method using surface-enhanced Raman spectroscopy (SERS), for detecting polystyrene nanoplastics (PSNPs). The SERS system used a simple mixture of spherical Au nanoparticles (AuNPs) and 20 nm nanoplastics deposited onto a filter paper which offered a detection limit of 10 μg mL -1 with a sample volume of 50 μL, and in a rare case 5.0 μg mL -1 (with four aliquits of 50 μL)., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A new approach has been developed for environmentally friendly C-C cross-coupling reactions using bi-functional Pd(ii)-salen complex-embedded cellulose filter paper (FP@Si-Pd II -Salen-[IM]OH). A Pd(ii)-salen complex bearing imidazolium [OH] - moieties was covalently embedded into a plain filter paper, then used as an efficient portable catalyst for the Heck, Suzuki, and Sonogashira cross-coupling reactions under environmentally friendly conditions via the filtration method. The catalytic filter paper properties were studied by EDX, XPS, TGA, ATR, XRD, and FESEM analyses. The reactions were catalyzed during reactants' filtration over the catalytic filter paper. The modified filter paper was set up over a funnel and the reactants were passed through the catalytic filter paper several times. The effect of reaction parameters including loading of Pd(ii)-salen complex, temperature, solvent, and contact time were carefully studied and also the optimal model of conditions was presented by the design expert software. High to excellent yields were obtained for all C-C coupling types with 5 to 8 filtration times. Under optimal conditions, all coupling reactions showed high selectivity and efficiency. Another advantage of the modified filter paper was its stability and reusability for several times with preservation of catalytic activity and swellability., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In general, during the papermaking process or the production of cellulosic materials for food-packaging applications, lignin and other amorphous components are usually removed via the pulping and multilevel bleaching process to entirely separate them from the fiber. The aim of this work was to study the positive effect that can impart the residual lignin remaining in the alkali-treated fiber surface over bleached fibers to produce an alternative food-packaging cellulosic paper. Herein, cellulosic papers based on alkali-treated and bleached fibers obtained from the Alfa plant were successfully prepared using a compression process. The as-obtained papers were coated by crosslinked starch using a solvent-casting method to improve their mechanical and surface properties. The morphological and contact angle results showed that the residual lignin in the alkali-treated cellulosic papers strongly increased the interfacial adhesion by making the structure denser and more compact, resulting in an improved water resistance property over the bleached ones. On the other hand, it also promoted char formation, slowing down the burning process, resulting in better flame resistance. Additionally, the mechanical properties demonstrated that the presence of lignin contributed to the material rigidity improvement without compromising its flexibility (folding endurance). The as-developed cellulosic papers coated with crosslinked starch could be used for the production of high-quality materials for food-packaging applications using conventional industrial processes., Competing Interests: The authors declare that they have no known competing financial interests. The manuscript has not been published elsewhere and that it has not been submitted simultaneously for publication elsewhere., (This journal is © The Royal Society of Chemistry.)

In search for more effective and eco-friendly adsorbent materials, this study comprehensively investigated Cd 2+ adsorption onto phosphorylated cellulose paper (PCP). For this, cellulose microfibers (CMF) was extracted from Alfa fibers and phosphorylated using the solid-state phosphorylation approach. Then, the prepared PCP samples were characterized by SEM, EDX, XRD, FTIR, TGA, conductometric titration and zeta potential measurement. The adsorption of cadmium ions, the effect of time, pH and Cd 2+ initial concentration were systematically studied in batch experiments. Based on the results, the highest adsorption capacity achieved was 479 mg of Cd 2+ per g of PCP, which was remarkable compared to other modified cellulose capacities cited in the literature. Furthermore, the Cd 2+ removal mechanism was investigated based on characterization results before and after adsorption and also based on the kinetics results. It was concluded that cation exchange and electrostatic attraction between phosphorylated cellulose and the cadmium ion mainly dominated the adsorption process. These findings highlighted that the phosphorylated cellulose paper has a broad application prospect in removal of divalent metal from aquatic solution., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this paper, a simple and cost-efficient strategy was used to construct a uniform Au NPs distribution on the surface of flexible filter paper for the detection of benzidine. Taking full advantage of the adsorption properties of filter paper, small gold nanoparticles were adsorbed onto its surface as gold seeds, and subsequently grown by electroless plating to form a highly uniform distribution of Au NPs substrates. By changing the electroless plating time, an optimal substrate was obtained. The as-prepared substrate exhibited satisfactory sensitivity with a low detection limit of 10 -13 M for 4-ATP, and good reproducibility and homogeneity. Furthermore, the as-prepared substrates were successfully used for the detection of benzidine in environmental water, with a minimum detection concentration as low as 0.1 ppm and recoveries in the range of 92.4 to ∼108.5%. This study indicated that filter paper-based SERS substrates have great potential value in the detection of environmental organic pollutants., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)