Modified Cellulose Paper Research Articles

Poly(3,4-dihydroxyphenylalanine)-modified cellulose paper for the extraction of deoxyribonucleic acid by a laboratory-built automated extraction device

The success of polymerase chain reaction (PCR) depends on the quality of deoxyribonucleic acid (DNA) templates. This study developed a cost-effective and eco-friendly DNA extraction system utilizing poly(3,4-dihydroxyphenylalanine)-modified cellulose paper (polyDOPA@paper). PolyDOPA@paper was prepared by oxidatively self-polymerizing DOPA under weak alkaline conditions and utilizing the adhesive property of polyDOPA on different materials. Compared to the uncoated cellulose paper, polyDOPA coating significantly enhances DNA adsorption owing to its abundant amino, carboxyl, and hydroxyl moieties. The DNA extraction mechanism using polyDOPA@paper was discussed. The maximum adsorption capacity of polyDOPA@paper for DNA was 20.7 μg cm−2. Moreover, an automated extraction system was designed and fabricated using 3D printing technology. The device simplifies the operation and ensures the reproducibility and consistency of the results. More importantly, it eliminates the need for specialized training of operators. The feasibility of the polyDOPA@paper-based automated extraction system was evaluated by quantitatively detecting Escherichia coli in spiked milk samples via a real-time PCR. The detection limit was 102 cfu mL−1. The results suggest that the system would have significant potential in detecting pathogens.

Foldable paper-based photoelectrochemical biosensor based on etching reaction of CoOOH nanosheets-coated laser-induced PbS/CdS/graphene for sensitive detection of ampicillin

Timely and rapid detection of antibiotic residues in the environment is conducive to safeguarding human health and promoting an ecological virtuous cycle. A foldable paper-based photoelectrochemical (PEC) sensor was successfully developed for the detection of ampicillin (AMP) based on glutathione/zirconium dioxide hollow nanorods/aptamer (GSH@ZrO2 HS@apt) modified cellulose paper as a reactive zone with laser direct-writing lead sulfide/cadmium sulfide/graphene (PbS/CdS/LIG) as photoelectrode and cobalt hydroxide (CoOOH) as a photoresist material. Initially, AMP was introduced into the paper-based reaction zone as a biogate aptamer, which specifically recognized the target and then left the ZrO2 HS surface, releasing glutathione (GSH) encapsulated inside. Subsequently, the introduction of GSH into the reaction region and etching of CoOOH nanosheets to expose the PbS/CdS/LIG photosensitive material increased photocurrent. Under optimal conditions, the paper-based PEC biosensor showed a linear response to AMP in the range of 5.0 - 2 × 104 pM with a detection limit of 1.36 pM (S/N = 3). In addition, the constructed PEC sensing platform has excellent selectivity, high stability and favorable reproducibility, and can be used to assess AMP residue levels in various real water samples (milk, tap water, river water), indicating its promising application in environmental antibiotic detection.

Photocatalytic/sorption-self-cleaning activity of cellulose decorated with TiO2 and M@TiO2 (M=Au, Ag) polymeric nanocomposites

Titanium oxide nanoparticles (TiO2 NPs) are a semiconductor material widely employed as photocatalysts for environmental remediation owing to its excellent properties. Nevertheless, collecting the nanomaterial once dispersed in the aqueous media is challenging, while the photocatalytic activity is limited mainly to the ultraviolet range of radiation. In this work, we have modified cellulose paper, a sustainable and green support, with a polymer nanocomposite comprising nylon-6 and different nanomaterials, i.e., anatase TiO2 nanoparticles (NPs) as well as TiO2 decorated with Ag and Au in form of NPs by means of a simple procedure. The immobilization of the nanocomposite on paper mediated the subsequent recovery of the substrate upon incubation. The presence of nylon-6 enables both the attachment of the NPs on the support as well as the isolation of the pollutant from the contaminated water due to the interactions with the target analyte, i.e., methyl orange (MO). Additionally, the presence of the mentioned polyamide within the substrate triggers the photocatalytic reaction under visible light radiation. The broadening in the range of the light towards the use of sunlight has been also evaluated via modification of the photocatalyst nanoparticles with noble metals such as silver and gold. The kinetic of degradation of MO upon sunlight exposure with the different polymeric nanocomposites followed a pseudo-first-order model, with k constant values of 0.070, 0.083 and 0.120 min−1 for TiO2, Ag@TiO2 and Au@TiO2 nanocomposites, respectively. The effect of the presence of the polymer on the substrate has been evaluated, observing an increase in the k constant upon addition of the polyamide from 0.036 to 0.069 min−1 for TiO2. The synergistic effect of sorption/degradation enables the regeneration of the substrates modified with the nanomaterials that can be reused several times, the relative standard deviation of k upon three subsequent photocatalytic cycles being in the range 15.7–37.7%.

Sustainable beeswax modified cellulose paper for the determination of tricyclic antidepressants in biofluids

This article describes the synthesis of sorptive phases for bioanalysis based on the modification of cellulose paper with natural beeswax as sorbent, resulting in a substrate completely renewable and sustainable. The preparation of the sorptive phases consisted of the dissolution of beeswax in hexane, followed by its drop-casting on cellulose paper and subsequent evaporation of the solvent. The beeswax modification of paper renders it hydrophobic, enabling the extraction of the target analytes, i.e., imipramine, desipramine, amitriptyline and trimipramine, via hydrophobic interactions. The main variables affecting the extraction performance were investigated (e.g., pH, ionic strength, extraction time, eluent composition, agitation speed). The analytical workflow combines a straightforward sampling, simultaneous extraction of 30 samples in 1 h, and the rapid (<2 min) determination of the analytes via direct infusion mass spectrometry. The method provided limits of detection in the range 2.0 and 3.2 μg L−1, and the precision, expressed as relative standard deviation, was better than 5.4 % and 8.5 % for intra and inter-day analyses, respectively. The accuracy, in terms of relative recovery, ranged from 90 % to 121 % using saliva as model biofluid.

Parallel Monitoring of Glucose, Free Amino Acids, and Vitamin C in Fruits Using a High-Throughput Paper-Based Sensor Modified with Poly(carboxybetaine acrylamide).

Herein, a cost-effective and portable microfluidic paper-based sensor is proposed for the simultaneous and rapid detection of glucose, free amino acids, and vitamin C in fruit. The device was constructed by embedding a poly(carboxybetaine acrylamide) (pCBAA)-modified cellulose paper chip within a hydrophobic acrylic plate. We successfully showcased the capabilities of a filter paper-based microfluidic sensor for the detection of fruit nutrients using three distinct colorimetric analyses. Within a single paper chip, we simultaneously detected glucose, free amino acids, and vitamin C in the vivid hues of cyan blue, purple, and Turnbull's blue, respectively, in three distinctive detection zones. Notably, we employed more stable silver nanoparticles for glucose detection, replacing the traditional peroxidase approach. The detection limits for glucose reached a low level of 0.049 mmol/L. Meanwhile, the detection limits for free amino acids and vitamin C were found to be 0.236 mmol/L and 0.125 mmol/L, respectively. The feasibility of the proposed sensor was validated in 13 different practical fruit samples using spectrophotometry. Cellulose paper utilizes capillary action to process trace fluids in tiny channels, and combined with pCBAA, which has superior hydrophilicity and anti-pollution properties, it greatly improves the sensitivity and practicality of paper-based sensors. Therefore, the paper-based colorimetric device is expected to provide technical support for the nutritional value assessment of fruits in the field of rapid detection.

Modified cellulose paper with photoluminescent acrylic copolymer nanoparticles containing fluorescein as pH-sensitive indicator

Herein, novel fluorescein mono-acrylate (Flu-Ac) was synthesized and copolymerized with methyl methacrylate and glycidyl methacrylate to produce epoxy-functionalized latex nanoparticles. Fluorescent cellulose paper was then obtained by dip-coating and subsequent heat treatment. Synthesis of Flu-Ac, its incorporation efficiency into the epoxy-functionalized nanoparticles (almost 92 %), spherical morphology of the particles and their sizes (89–93 nm), and optical properties were studied comprehensively. SEM micrographs showed effective wetting of the cellulose fibers with uniform diffusion and deposition of the prepared functional nanoparticles through the establishment of physical and chemical interactions. Visual and spectroscopic emission intensity of the impregnated cellulose paper (λmax of 529 nm) were enhanced by increasing pH of the solution (from 2 to14) as a consequence of the transformation of cationic fluorescein to its neutral and anionic form. These observations depicted that such fluorescent cellulose substrates could be exploited in reusable indicators with good ability for sensing pH of solutions with diverse acidity or basicity.

MOFs Modified Paper-Based Materials: Preparation and Application to EtOH Fluorescence Response

Based on the solvothermal method, two new MOFs with 3-(1-Oxo-1H-2,3-dihydroisoindol-2-yl)benzoic acid as the organic ligand, Zn-HBPA and Zn-bpy-HBPA were synthesized. The structure of MOFs was characterized by 1H-NMR, XRD, FT-IR and SEM. A series of modified cellulose paper-based functional materials with different spraying times were prepared by flame spraying method, and the fluorescence property of MOFs modified cellulose paper to EtOH small molecules was investigated by fluorescence spectrometer. The results of FT-IR and SEM showed that the flame spraying method could effectively improve the retention rate of MOFs on cellulose paper materials. The PL characterization results displayed that Zn-HBPA@PFP exhibited a decrease in fluorescence after UV irradiation, while Zn-bpy-HBPA@PFP demenstrated an increase in fluorescence at λ=338 nm. The above results indicated that Zn-bpy-HBPA@PFP had an excellent response ability to EtOH small molecules, and when Cycle=7 times, Zn-bpy-HBPA@PFP had the best fluorescence enhancement effect.

Hybrid "Kill and Release" Antibacterial Cellulose Papers Obtained via Surface-Initiated Atom Transfer Radical Polymerization.

Infectious diseases triggered by bacteria cause a severe risk to human health. To counter this issue, surfaces coated with antibacterial materials have been widely used in daily life to kill these bacteria. The substrates enabled with a hybrid kill and release strategy can be employed not only to kill the bacteria but also to wash them using external stimuli (temperature, pH, etc.). Utilizing this concept, we develop thermoresponsive antibacterial-cellulose papers to exhibit hybrid kill and release properties. Thermoresponsive copolymers [p(NIPAAm-co-AEMA)] are grafted on cellulose papers using a surface-initiated atom transfer radical polymerization approach for bacterial debris release. Later for antibacterial properties, silver nanoparticles (AgNPs) are immobilized on thermoresponsive copolymer-grafted cellulose papers using electrostatic interactions. We confirm the thermoresponsive copolymer grafting and AgNP coating by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. Thermoresponsiveness and reusability of the modified cellulose papers are confirmed through water contact angle measurements. The interaction potency between AgNPs and modified cellulose is validated by inductively coupled plasma atomic emission spectroscopy analysis. Gram-negative bacteria Escherichia coli (E. coli DH5-α) is used to demonstrate antibacterial hybrid kill and release performance. Agar-diffusion testing demonstrates the antibacterial nature of the modified cellulose papers. The fluorescence micrograph reveals that modified cellulose papers can effectively release almost all the dead bacterial debris from their surfaces after thermal stimulus wash. The modified cellulose paper surfaces are expected to have wide applications in the field of exploring more antibacterial and smart surfaces.

Flexible humidity sensor based on modified cellulose paper

Abstract It is of great significance to exploit a simple, cost-effective and environmentally friendly preparation method of multifunctional humidity sensors. However, most humidity sensors need complex manufacturing processes, high cost and narrow usage range. Herein, humidity sensors based on glycidyl trimethyl ammonium chloride (EPTAC) modified cellulose paper via a facile solution method were fabricated, among which the paper is used for the purpose of the humidity sensing material and the sensor substrate. The sensitivity of the obtained sensor was improved by the modification of EPTAC, the response time was decreased to 25 s, which is equivalent to the first-rate paper-based humidity sensors. In addition, the paper-based humidity sensor is provided with well flexibility and biocompatibility, and it exhibits multifunctional applications in respiratory monitoring, non-contact switch and skin humidity monitoring. The low cost and facile preparation technique in this work could provide a useful strategy for developing multifunctional humidity sensor.

Grafting polysulfonamide from cellulose paper through organocatalytic ring-opening polymerization of N-sulfonyl aziridines

A facile and effective “grafting from” method by ROP of N-sulfonyl aziridines toward cellulose-g-polysulfonamides has been developed for efficient oil/water separation. The cellulose paper was initially succinylated to transform the hydroxyl to carboxyl acid groups, which act as the initiating sites for the ring-opening copolymerization of fluorescent 2-methyl-1-dansylaziridine and 2-methyl-1-tosylaziridine (TsMAz) towards the grafted cellulose. Both steps are catalyzed by the same compound, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD). The grafted polysulfonamide ratio was up to 136 wt%, and the surface contact angle up to 147°. A one-pot tandem strategy was applied to produce the grafted cellulose paper with a grafting ratio ranging from 96 to 150 % and a contact angle over 127°. The modified cellulose paper material showed promising properties for efficient oil/water separations.

One-pot fabrication of amino acid and peptide stabilized gold nanoclusters for the measurement of the lead in plasma samples using chemically modified cellulose paper

The ultra-small size, excellent photo-stability, and tremendous fluorescence properties make the gold nanoclusters (AuNCs) as novel chemo- and biosensors. Herein, a one-pot approach was implemented for fabricating highly fluorescent AuNCs using histidine (His) and glutathione (GSH) as a reducing and protecting agent. As-synthesized GSH-AuNCs@His exhibits bright green fluorescence with excitation and emission peak of 420 and 502 nm, respectively, with a quantum yield of 7.5 %. The GSH conjugated with law fluorescent AuNCs@His through the free amines of His, and then utilized for the nanomolar detection of Pb2+ ion in aqueous solution via selective fluorescence turn-off mechanism with linear concentration range 5.0−1000 nM. The detection limit for Pb2+ ion was calculated 1.0 nM, which is much lower than the allowed concentration of Pb2+ ion in drinking water. The synthesized GSH-AuNCs@His was applied to Pb2+ ion within the spiked plasma sample and obtained excellent recovery with good precision and accuracy. The study also presents chemically modified cellulose paper strips with the conjugated GSH-AuNCs@His for the detection of Pb2+ ion.

Experimental comparison of surface chemistries for biomolecule immobilization on paper-based microfluidic devices

Biomolecules (e.g. proteins and nucleic acids) as target analytes of microfluidic paper-based analytical devices (μPADs) are usually immobilized on a cellulose paper substrate (with intrinsically anionic surface) through physical adsorptions by van der Waals forces and electrostatic interaction thanks to cationic patches on the biomolecule. However, the physical adsorption could lead to weak biomolecule-substrate binding strength and thus low biosensing performance. Benefitting from the abundance of hydroxyl groups on the cellulose paper, chemical modification based on specific surface chemistries is capable of biofunctionalization on the μPADs by providing functional groups for covalent bindings with the target biomolecule. There are many previous reports on chemical modifications of cellulose surface for improvement of biomolecule immobilization. Nevertheless, no study has been performed on experimental evaluation of modification efficiencies of various biofunctionalization methods in the context of biosensing applications. In this paper, we compare five surface chemistries for protein immobilization on μPADs made from pure cellulose paper. For each chemical modification method, surface analyses were first conducted to monitor the surface modification process. Then, paper-based fluorometric experiments and colorimetric enzyme-linked immunosorbent assays (ELISA) were carried out on paper substrates modified by the five surface chemistries to compare their efficiencies of covalent protein immobilization. Finally, a stability experiment was carried out on the five types of surface-modified paper after 30 d storage. It was demonstrated that the potassium periodate (KIO4)-modified cellulose paper has the best performance with 53% increase in the signal output and 59% decrease in background noise of the colorimetric ELISA, and only 13% bioactivity loss after the 30 d storage. The comparison results provide a valuable experimental guideline for selecting the suitable surface chemistry for protein immobilization on μPADs.

Solid-phase microextraction of triazine herbicides via cellulose paper coated with a metal-organic framework of type MIL-101(Cr), and their quantitation by HPLC-MS.

Cellulose paper was coated with the metal-organic framework MIL-101(Cr) in a chitosan matrix and utilized for thin-film microextraction (TFME). The coated paper possesses excellent extraction efficiency for the triazine herbicides atraton, desmetryn, secbumeton, prometon, ametryn, dipropetryn, and dimethametryn. High-performance liquid chromatography-tandem mass spectrometry was applied to quantify target analytes. The effects of mass ratio of MIL-101(Cr) to chitosan, sample pH value, time of adsorption and desorption, and type and volume of desorption solvent on extraction efficiency were optimized. Under the optimal conditions, the method has limits of detection between 1.5 and 22ng·L-1. The recoveries of triazines from spiked tap water, drinking water, lake water and river water range from 77.0 to 125.3%, with relative standard deviations of <17.4%. Graphical abstract Cellulose paper was modified with metal-organic framework MIL-101(Cr)/chitosan by using a simple, efficient and environmentally friendly approach. The modified cellulose paper was then used as a novel extraction phase in thin-film microextraction (TFME).

Design and preparation of a cellulose-based adsorbent modified by imidazolium ionic liquid functional groups and their studies on anionic dye adsorption

Adsorption of dyes via strong interactions between modified cellulose paper and dyes is an economical, effective, and sustainable method for treating wastewater. In this work, using multiple interactions with dye molecules, an imidazolium ionic liquid modified cellulose adsorbent (CCP-Im) was prepared and used to treat anionic dye wastewater effectively. Zeta potential tests and Gaussian simulations revealed the strong interactions between CCP-Im and anionic dye molecules. Under optimum adsorption conditions, CCP-Im has good adsorption capacity for anionic dyes, and the maximum adsorption capacities of xylenol orange and Congo red could reach 1169 and 563 mg g−1, which were 3.1 and 3.5 times, respectively, higher than the values of the original cellulose paper. The Freundlich and Scatchard models for isothermal study demonstrated the adsorption process of CCP-Im toward anionic dyes occurred on a heterogeneous surface via multilayer sorption, and the kinetics revealed that a Pseudo-second-order model described the adsorption process well, indicating the adsorption was controlled by the mechanism of chemical adsorption. Therefore, preparation of this bioadsorbent would be useful for environmental protection and development of sustainable resources.

A paper-based multiplexed resonance energy transfer nucleic acid hybridization assay using a single form of upconversion nanoparticle as donor and three quantum dots as acceptors

Monodisperse aqueous upconverting nanoparticles (UCNPs) were covalently immobilized on aldehyde modified cellulose paper via reductive amination to evaluate the multiplexing capacity of luminescence resonance energy transfer (LRET) between UCNPs and quantum dots (QDs). This is the first account of a multiplexed bioassay strategy that demonstrates the principle of use of a single form of UCNP as donor and three different color emitting QDs as acceptors to concurrently determine three analytes. Broad absorbance profiles of green, orange and red QDs that spanned from the first exciton absorption peak to the UV region were in overlap with a blue emission band from UCNPs composed of NaYF4 that was doped with 30% Yb3+, 0.5% Tm3+, allowing for LRET that was stimulated using 980 nm near-infrared radiation. The characteristic narrow and well-defined emission peaks of UCNPs and QDs allowed for the collection of luminescence from each nanoparticle using a band-pass optical filter and an epi-fluorescence microscope. The LRET system was used for the concurrent detection of uidA, Stx1A and tetA gene fragments with selectivity even in serum samples, and reached limits of detection of 26 fmol, 56 fmol and 76 fmol, respectively.

Detection of a cancer biomarker protein on modified cellulose paper by fluorescence using aptamer-linked quantum dots.

The development of point-of-care bioassays for sensitive screening of protein-based cancer biomarkers would improve the opportunity for early stage diagnosis. A strategy for a fluorescence resonance energy transfer (FRET)-based bioassay has been investigated that makes use of modified cellulose paper for the detection of an epithelial cell adhesion molecule (EpCAM), which is a transmembrane glycoprotein that is overexpressed in several tumors of epithelial origin. The paper matrix was a substrate for immobilized aptamer-linked quantum dots (QDs-Apt) and Cy3 labeled complementary DNA (cDNA), which served as a donor and an acceptor, respectively. Competitive binding of EpCAM displaced the cDNA, resulting in the reduction of FRET. The paper-based bioassay was able to detect EpCAM in buffer solution as well as in 10% bovine serum solution using a reaction time of no more than 60 minutes. The dynamic range was 1-100 nM in buffer with a precision better than 4%, and the limit of detection was 250 pM in buffer and 600 pM in 10% serum.

Resonance Energy Transfer-Based Nucleic Acid Hybridization Assays on Paper-Based Platforms Using Emissive Nanoparticles as Donors.

Quantum dots (QDs) and upconverting nanoparticles (UCNPs) are luminescent nanoparticles (NPs) commonly used in bioassays and biosensors as resonance energy transfer (RET) donors. The narrow and tunable emissions of both QDs and UCNPs make them versatile RET donors that can be paired with a wide range of acceptors. Ratiometric signal processing that compares donor and acceptor emission in RET-based transduction offers improved precision, as it accounts for fluctuations in the absolute photoluminescence (PL) intensities of the donor and acceptor that can result from experimental and instrumental variations. Immobilizing NPs on a solid support avoids problems such as those that can arise with their aggregation in solution, and allows for facile layer-by-layer assembly of the interfacial chemistry. Paper is an attractive solid support for the development of point-of-care diagnostic assays given its ubiquity, low-cost, and intrinsic fluid transport by capillary action. Integration of nanomaterials with paper-based analytical devices (PADs) provides avenues to augment the analytical performance of PADs, given the unique optoelectronic properties of nanomaterials. Herein, we describe methodology for the development of PADs using QDs and UCNPs as RET donors for optical transduction of nucleic acid hybridization. Immobilization of green-emitting QDs (gQDs) on imidazole functionalized cellulose paper is described for use as RET donors with Cy3 molecular dye as acceptors for the detection of SMN1 gene fragment. We also describe the covalent immobilization of blue-emitting UCNPs on aldehyde modified cellulose paper for use as RET donors with orange-emitting QDs (oQDs) as acceptors for the detection of HPRT1 gene fragment. The data described herein is acquired using an epifluorescence microscope, and can also be collected using technology such as a typical electronic camera.

Writing and erasing hidden optical information on covalently modified cellulose paper.

An unprecedented strategy for preparing photoresponsive cellulose paper enabling the storage of short-lived optical data by covalent photopatterning is disclosed. An ab initio design hinting that the covalent grafting of coumarins on the paper could yield valuable photoresponsive units was first performed. Second, light sensitive paper that can be reversibly altered upon irradiation at a specific wavelength was prepared by covalent surface functionalization with coumarins. Third, the validity of this strategy is demonstrated using the photolithography of several gripping patterns such as a dynamic QR code.

A paper-based resonance energy transfer nucleic acid hybridization assay using upconversion nanoparticles as donors and quantum dots as acceptors

Monodisperse aqueous upconverting nanoparticles (UCNPs) were covalently immobilized on aldehyde modified cellulose paper via reduction amination to develop a luminescence resonance energy transfer (LRET)-based nucleic acid hybridization assay. This first account of covalent immobilization of UCNPs on paper for a bioassay reports an optically responsive method that is sensitive, reproducible and robust. The immobilized UCNPs were decorated with oligonucleotide probes to capture HPRT1 housekeeping gene fragments, which in turn brought reporter conjugated quantum dots (QDs) in close proximity to the UCNPs for LRET. This sandwich assay could detect unlabeled oligonucleotide target, and had a limit of detection of 13fmol and a dynamic range spanning nearly 3 orders of magnitude. The use of QDs, which are excellent LRET acceptors, demonstrated improved sensitivity, limit of detection, dynamic range and selectivity compared to similar assays that have used molecular fluorophores as acceptors. The selectivity of the assay was attributed to the decoration of the QDs with polyethylene glycol to eliminate non-specific adsorption. The kinetics of hybridization were determined to be diffusion limited and full signal development occurred within 3min.

Detection of telomerase on upconversion nanoparticle modified cellulose paper.

Herein we report a convenient and sensitive method for the detection of telomerase activity based on upconversion nanoparticle (UCNP) modified cellulose paper. Compared with many solution-phase systems, this paper chip is more stable and easily stores the test results. What's more, the low background fluorescence of the UCNPs increases the sensitivity of this method, and the low telomerase levels in different cell lines can clearly be discriminated by the naked eye.