Abundant Carboxyl Research Articles

Polylevodopa nanoplatform for lateral flow immunochromatography assay of SARS-CoV-2 and influenza A virus

At the end of 2019, an unprecedented outbreak of novel coronavirus pneumonia ravaged the global landscape, inflicting profound harm upon society. Following numerous cycles of transmission, we find ourselves in an epoch where the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coexists alongside influenza viruses (Flu A). Swift and accurate diagnosis of SARS-CoV-2 and Flu A is imperative to stem the spread of these maladies and administer appropriate treatment. Presently, colloidal gold-based lateral flow immunoassays (Au-LFIAs) constructed through electrostatic adsorption are beset by challenges such as diminished sensitivity and feeble binding stability. In this context, we propose the adoption of black polylevodopa nanoparticles (PLDA NPs) featuring abundant carboxyl groups as labeling nanomaterials in LFIA to bolster the stability and sensitivity of SARS-CoV-2 antigens and influenza A virus identifications. The engineered PLDA-LFIAs exhibit the capacity to detect SARS-CoV-2 and Flu A within 30 min, boasting a detection threshold of 5 pg/ml for the SARS-CoV-2 antigen and 0.1 ng/ml for the Flu A H1N1 antigen, thereby underscoring their heightened sensitivity relative to Au-LFIAs. These PLDA-LFIAs hold promise for the early detection of SARS-CoV-2 and Flu A, underscoring the potential of PLDA NPs as a discerning labeling probe to heighten the sensitivity of LFIA across diverse applications.

Synthesis of poly(maleic anhydride-co-vinyl chloride) crosslinked microspheres and its superior enhancement in mechanical strength and antibacterial activity for poly(vinyl alcohol) composite films

Poly(vinyl alcohol) (PVA) is an attractive raw material and widely applicated in multiple fields owing to its unique features. However, the poor mechanical strength and without intrinsic antimicrobial activity severely restrained its further use. Herein, we proposed a novel strategy to fabricate PVA-based composites film with excellent mechanical properties and superior antibacterial activity by employing functional polymeric microspheres as a hydrogen bonding cross-linker and bactericide loading platform. Firstly, we synthesized poly(maleic anhydride-co-vinyl chloride) cross-linked microspheres (PDVM) via self-stabilized precipitation polymerization and subsequently the PDVM microspheres were reacted with gaseous ammonia to endow the microsphere surface with abundant carboxyl and amidogen group. As a result, uniform PDVM microspheres with diameters ranging from 175 to 685 nm and controlled gel content (25.3–91.8%) were prepared successfully and aminolyzed PDVM microsphere (NPDVM) were obtained. By incorporating 5 wt% NPDVM in PVA matrix, the composite film has a significant increment in tensile strength (63.9 MPa) and elongation at break (107 %) in comparison to neat PVA (51.8 MPa, 80%) mainly attributed to the formation of multiple hydrogen bonding network. Furthermore, by immobilizing Zn2+ on the surface of NPDVM/PVA film via complexation, the composite film exhibited outstanding antibacterial efficiency against E. coli and S. aureus.

Commercial Wheat and Oat Flour Derived Fluorescent Carbon Quantum Dots through Sustainable Hydrothermal Synthesis and Their Biological Activities

AbstractIn this study, we utilized processed edible commercial wheat and oat flours to synthesize highly fluorescent carbon dots using green hydrothermal synthesis. The as‐synthesized carbon quantum dots (CQDs) were characterized using UV‐vis spectrophotometry, photoluminescence spectrophotometry, high‐resolution transmission electron microscopy, and Fourier transform infrared spectroscopy. The synthesized wheat‐CQDs (W‐CQDs) and oat‐CQDs (O‐CQDs) had monodispersed spherical shapes with average sizes of 3–8 and 5–10 nm, respectively, and exhibited strong fluorescence intensity and excitation‐dependent photoluminescence. The W‐CQDs and O‐CQDs were highly dispersed in aqueous solutions and exhibited bright green and blue fluorescence, respectively, under UV light (λex=380 and 370 nm). Both CQDs contained abundant functional groups, including amino, hydroxyl, and carboxyl groups, which may play a major role in biological applications. The W‐CQDs and O‐CQDs showed good free‐radical scavenging capacity in the 2,2‐diphenylpicrylhydrazyl (DPPH) and H2O2 assays. The anti‐inflammatory activities of W‐CQDs and O‐CQDs were more effective than that of the standard, with EC50 values of 1.8 and 1.3 mg/mL, respectively, in the protein denaturation assay. Additionally, the CQDs exhibited low cytotoxicity toward NIH3T3 fibroblast and human HeLa cervical cancer cells when treated with a 5‐mg/mL concentration. Therefore, green‐synthesized W‐CQDs and O‐CQDs are easily available, less cytotoxic, and applicable to therapeutic and cell nanocarrier purposes.

Unraveling the characteristics of dissolved organic matter removed by aluminum species based on FT-ICR MS analysis

Given the complexity of dissolved organic matter (DOM) and its interactions with coagulant chemicals, the mechanisms of DOM removal by aluminum (Al) coagulants remains a significant unknown. In this study, six test waters containing DOM with molecular weight (MW, <1 kDa, 1–10 kDa and >10 kDa) and hydrophobicity (hydrophilic, transphilic and hydrophobic) were prepared and coagulated with Al0, Al13 and Al30. The molecular-level characteristics of DOM molecules that were removed or resistant to removal by Al species were analyzed using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The results showed that at the molecular level, saturated and reduced tannins and lignin-like compounds containing abundant carboxyl groups exhibited higher coagulation efficiency. Unsaturated and oxidized lipids, protein-like, and carbohydrates compounds were relatively resistant to Al coagulation due to their higher polarity and lower content of carboxyl groups. Al13 removed molecules across a wider range of molecular weights than Al0 and Al30, thus the DOC removal efficiency of Al13 was the highest. This study furthers the understanding of interactions between Al species and DOM, and provides scientific insights on the operation of water treatment plants to improve control of DOM.

Carboxylated PIM‐1 incorporating sulfonated graphene oxide effectively improves the ion transport properties of the membrane

AbstractThis study explores the ion transport properties of self‐microporous polymers by introducing a novel combination of carboxylated PIM‐1 with sulfonated graphene oxide (SGO) to fabricate membranes. The resulting membranes exhibit enhanced structural stability, hydrophilicity, and ion exchange capacity (IEC) compared with the original carboxylated PIM‐1 (CPIM‐1), while preserving the subnanoporous structure. However, it was observed that excessive SGO loading leads to a detrimental “blocking effect” that compromises various membrane properties. Through electrically driven ion transport tests in a 0.01 M NaCl solution, it is demonstrated that a moderate amount of SGO effectively enhances membrane conductivity from 46.96 μS m−1 (for carboxylated PIM‐1 membranes without SGO) to 56.55 μS m−1. Additionally, the membranes exhibit selective sieving of cations and anions. The presence of small‐sized ion channels and the electrostatic repulsion generated by the abundant carboxyl and sulfonic acid groups significantly hinder Cl− transport. Consequently, the Na+/Cl− migration ratio (t+/t−) reaches 98 at a concentration ratio of 10:1 on both sides of the membrane, surpassing the value of 3.74 observed for the pure CPIM‐1 membrane. This investigation provides valuable insights for the practical application of easily prepared, processable, and cost‐effective hydrophilic self‐contained microporous polymer membranes in ion transport applications.

Fabrication of novel 4-methyl-5-thiazoleethanol covalently-linked graphene oxide composite with adsorption selectivity for Cu2+ from aqueous solutions

BackgroundThe covalent coupling of specific organic components to graphene oxide (GO) can improve its adsorption selectivity and reduce its hydrophilicity for fast separation by acylation of the abundant carboxyl groups (-COOH) on the surface. MethodsIn this study, a novel composite material with excellent adsorption selectivity toward copper ions (Cu2+) was prepared by covalent-linking of 4-methyl-5-thiazoleethanol (MTE) to GO through a facile one-step esterification reaction. The composition and morphology of GO-MTE composites pre- and after-adsorption of Cu2+were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analyses. The adsorption conditions of GO-MTE composite for Cu2+were investigated and optimized. To further reveal the possible adsorption mechanism of GO-MTE composite toward Cu2+, the experimental data were fitted by different adsorption dynamics and isothermal models. The reusability of GO-MTE composite was evaluated by repeating the adsorption/desorption experiments in eight consecutive cycles. Significant findingsThe introduction of MTE effectively inactivates most of the carboxyl groups of GO, and the covalently-linked thiazole ring with N- and S-containing heteroatoms endows GO-MTE composite with excellent adsorption selectivity for Cu2+ in aqueous solution. The adsorption capacities of GO-MTE composite for Cu2+ are 2.39, 17.08 and 26.64 times higher than those of Pb2+, Nd3+ and Y3+, respectively, indicating that it possesses stronger binding ability for Cu2+. After eight adsorption/desorption cycles, the recycled GO-MTE composite still maintained high adsorption capacity and removal rate for Cu2+, indicating that GO-MTE composite possesses excellent stability and reusability, and it could be used for the separation and recovery of Cu2+ from aqueous solutions.

Shape-memory cellulose nanofiber/polyglutamic acid-based aerogels as novel adsorbents for the removal of heavy metals from aqueous solutions

Water bodies contaminated by heavy metals pose a severe threat to human health and the eco-system. The synthesis of eco-friendly adsorbents is essential to eliminate the use of toxic chemicals to eradicate heavy metal pollution from water bodies. In this study, a novel aerogel was prepared using a simple one-pot reaction between cellulose nanofibers and polyglutamic acid through a crosslinking reaction for the removal of lead, zinc, and copper ions from aqueous solutions. Surface analysis revealed that the aerogel consisted of abundant carboxyl and amino functional groups. The optimal pH of the solution for the adsorption of lead, zinc, and copper was 4, 5, and 5 respectively. The experimental data revealed that the adsorption followed pseudo-second-order kinetics at 22 °C for all the heavy metals. The adsorption behaviour of zinc and copper could be described through the Langmuir isotherm model whereas, the adsorption behaviour of lead was described by the Freundlich isotherm model. The maximum experimental adsorption capacity was 101.81, 59.26, 100.59 mg/g for lead, zinc, and copper respectively. The adsorption mechanisms involved were coordination bonding and electrostatic attraction. The high adsorption capacity, ease of separability and good mechanical strength deems these aerogels suitable for the adsorption of heavy metals from water.

Smartphone-assisted carbon dots fluorescent sensing platform for visual detection of Thiophanate-methyl in fruits and vegetables

Trimesic acid and o-phenylenediamine (OPD) were employed as precursors to synthesize yellow-green fluorescent carbon dots (Y-G-CDs) by solvothermal synthesis for the sensitive detection of Thiophanate-methyl (TM) in real agricultural products. The Y-G-CDs probe could specifically recognize the TM primarily through π-π stacking. Moreover, the fluorescence quenching of the probe was ultimately dominated by the PET effect, based on the interaction between the abundant carboxyl groups on the surface of the Y-G-CDs and the amino group of TM. A strong linear relationship between the fluorescence quenching of the probe and TM concentration in the range of 0–10 µmol/L was observed and the limit of detection (LOD) was calculated to be 50.7 nmol/L. Compared to the interference pesticides, the Y-G-CDs probe demonstrated exceptional selectivity toward TM, with satisfactory recoveries of 96.3 % − 104.2 % in spiked food samples. The Y-G-CDs probe enables simple pretreatment, cost-effective, and on-site detection of TM in fruits and vegetables with visual detection of the TM employing a smartphone-assisted sensing platform.

Comparison of Pb2+ Adsorption Properties of Biochars Modified Through CO2 Atmosphere Pyrolysis and Nitric Acid

Acid modification has been widely used to modify the structural properties of biochars. However, acid modification led to the large consumption of acid, increased difficulty of waste effluent disposal, and a high application cost. To evaluate the advantages and application potential of biochars prepared under CO2, utilizing pyrolysis to directly modify biochars to improve heavy metal removal efficiency and reduce production cost, would be an important prerequisite for the broad application of biochars. The sorption performance of Pb2+ with CO2-modified biochars was compared with that of HNO3-modified biochar. The elemental compositions and structural properties of biochars were characterized through elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results revealed that for biochars produced at 500℃, HNO3 modification produced abundant carboxylic groups and -NO2 (asy) and -NO2 (sym) groups, promoting the surface activities and complexing abilities of biochars. The CO2-modified biochars contained abundant carbonate minerals, which could remove Pb2+ by electrostatic ion exchange and coprecipitation or complex. In addition, compared to that of HNO3-modified biochars, CO2-modified biochars had the larger specific surface area and better microporous structures, which were beneficial to the diffusion of Pb2+ and further promoted surface sorption. CO2 modification increased the maximum Pb2+ sorption capacity of W500CO2 and W700CO2, which were 60.14 mg·g-1 and 71.69 mg·g-1. By contrast, HNO3-modified biochars W500N2-A and W700N2-A showed the lower Pb2+ sorption capacities, which were 42.26 mg·g-1 and 68.3 mg·g-1, respectively. The increasing of the specific surface area and functional groups simultaneously promoted the sorption capacity of CO2-modified biochars. Consequently, the CO2-modified biochar had the advantages of low cost, environmental friendliness, and high heavy metal removal efficiency, which is a modification method worthy of promotion and application.

An Intrinsic Self-Healable, Anti-Freezable and Ionically Conductive Hydrogel for Soft Ionotronics Induced by Imidazolyl Cross-Linker Molecules Anchored with Dynamic Disulfide Bonds.

Hydrogels are ideal materials for flexible electronic devices based on their smooth ion channels and considerable mechanical flexibility. A substantial volume of aqueous solution is required to enable the smooth flow of ions, resulting in the agony of low-temperature freezing; besides, long-term exposure to bending/tensile tress triggers fatigue issues. Therefore, it is a great challenge to prepare hydrogels with both freeze-resistance and long-term durability. Herein, a polyacrylic acid-based hydrogel with both hydrophobic interaction and dynamic reversible covalent bonding cross-linking networks is preparing (DC-hydrogel) by polymerizing a bi-functional imidazole-type ionic liquid monomer with integrated disulfide and alkene bonds (DS/DB-IL) and an octadecyl methacrylate, achieving self-healing. The DS/DB-IL anchored into the polymer backbone has a high affinity with water, reducing the freezing point of water, while the DS/DB-IL with free ions provides superior ionic conductivity to the DC-hydrogel. The polyacrylic acid with abundant carboxyl gives hydrogel good self-adhesiveness to different substrates. Ionotronics with resistance-type sensors with stable output performance are fabricated and explored its application to joint motion and health information. Moreover, hydrogel-based sensing arrays with high resolution and accuracy are fabricated to identify 2D distribution of stress. The hydrogels have great promise for various ionotronics in many fields.

Self‐Assembled Robust Interfacial Layer for Dendrite‐Free and Flexible Zinc‐Based Energy Storage

AbstractAqueous zinc‐based energy storage systems (Zn‐ESSs) with intrinsic safety and good electrochemical performance are promising power suppliers for flexible electronics, whereas unstable zinc anodes especially in flexible Zn‐ESSs pose a challenge. Herein, a self‐assembled robust interfacial layer to achieve stable zinc anodes in non‐flexible and flexible Zn‐ESSs is reported. Specifically, zinc anodes and their slowly‐released Zn2+ simultaneously interact with tannic acid molecules in ethanol–water solutions, triggering the self‐assembly of a tannic acid/Zn2+ complex interfacial layer (CIL) that firmly anchors on the zinc anodes. The CIL containing abundant carboxyl and phenolic hydroxyl functional groups provides rich zincophilic sites to homogenize Zn2+ flux and accelerate Zn2+ desolvation‐deposition, and traps H+/H2O species to prevent them from corroding zinc anodes, thereby stabilizing the zinc deposition interface. Consequently, the CIL@Zn anodes present superior stability with an operation lifetime exceeding 700 h even at 5 mA cm−2 (28 times longer than that of bare zinc anodes) and ultrahigh cumulative plated capacity of ≈1.8 Ah cm−2. The firm anchoring of the CIL enables the CIL@Zn anodes to endure diverse deformations, thus realizing highly flexible CIL@Zn anode‐based Zn‐ESSs. This work provides thinking in designing stable and flexible zinc anodes, promoting the development of flexible zinc‐based energy storage.

Coating Fe3O4 quantum dots with glutamic acid to achieve enhanced catalysis for facile and sensitive detection of chromium(VI) in water.

A universal green synthesis approach for Glu-Fe3O4 quantum dots (QDs) with ultrasmall size (∼3.3 nm) and enhanced catalysis was demonstrated using glutamic acid (Glu) as a dopant. Abundant carboxylic groups and amino groups on the surfaces with a zeta potential of -6.28 mV resulted in greatly improved environmental stability. The Glu-Fe3O4 QDs exhibited oxidoreductase-like catalytic activity. The steady-state kinetic assays indicated that the QDs had a high binding affinity for the substrate TMB. A facile and sensitive colorimetric platform was developed using the Glu-Fe3O4 QDs for the detection of Cr(VI) in naturally sourced water and waste water, which showed a detection limit of 31.02 nM, much lower than the maximum Cr(VI) level permitted in drinking water by the World Health Organization (WHO) and the industrial water threshold. This universal green synthesis approach and the unique catalytic activity of Fe3O4 QDs open a new horizon in materials chemistry and the development of colorimetric biosensors for environmental protection and public health.

A lipase-conjugated carbon nanotube fiber-optic SPR sensor for sensitive and specific detection of tributyrin.

As a low-density lipoprotein, tributyrin plays an essential role in food safety and human health. In this study, a novel lipase-conjugated carbon nanotube (CNT) surface plasmon resonance (SPR) fiber-optic sensor is used to specifically detect tributyrin for the first time. In this work, CNTs can be used as an amplifying material to significantly increase the sensitivity of SPR sensors due to their high refractive index and large surface area. CNTs can also be used as an enzyme carrier to provide abundant carboxyl groups for the specific binding of lipases. Covering the surface of the sensor with CNTs can not only enhance the performance of the sensor, but also provide sufficient detection sites for subsequent biomass detection, reduce the functionalization steps, and simplify the sensor preparation process. The experimental results demonstrate that the refractive index sensitivity of the traditional multimode fiber (MMF)-single mode fiber (SMF)-MMF transmissive optical fiber sensor is 1705 nm RIU-1. After covering the sensor with CNTs, the sensitivity is 2077 nm RIU-1, and the sensitivity has been improved very well. In addition, there are abundant functional groups on CNTs, which can provide abundant binding sites. Conjugating lipase on carbon nanotubes helps to achieve linear detection in the range of 0.5 mM to 4 mM tributyrin, with a sensitivity of 4.45 nm mM-1 and a detection limit of 0.34 mM, which is below the 2.26 mM detection standard and meets food safety monitoring requirements. Compared with other sensors, the optical fiber biosensor proposed in this study expands the concentration detection range of tributyrin. Furthermore, the sensor also has good stability, anti-interference performance and specificity. Therefore, the sensor proposed in this paper has good application prospects in the fields of food safety and biomedicine.

A reusable graphene oxide aerogel for pre-concentrating and recovering uranium from water and valorisation of spent material in a cementitious material

Graphene oxide is an excellent substrate for pre-concentrating and recovering uranium in water. However, the need for scalable and affordable methods for producing graphene oxide has hindered its field applications. Besides, a sustainable strategy is required to recycle spent adsorbents and prevent them from entering the waste stream. In these contexts, this paper describes the application of graphene oxide aerogel (GOA) produced from graphite through a single-step combustion route for pre-concentrating and recovering uranium in water. The method allows GOA production in bulk quantity at 8–10 times less cost than prevalent Modified Hummer's graphene oxide (HGO). The paper also demonstrates using spent GOA as an active admixture in mortar to improve its mechanical properties. The physicochemical properties of the GOA and mechanistic details of uranium surface bindings were studied thoroughly. GOA showed enhanced uranium adsorption capacity (278 mg/g) compared to HGO due to abundant hydroxyl, carboxyl, and epoxy groups on GOA. However, the presence of HCO3− in water reduced uranium uptake due to highly water-soluble uranium-carbonate complexes such as (UO2)2CO3(OH)3−,UO2(CO3)34−, and UO2(CO3)22−. The addition of the spent GOA improved the cement mortar's compressive strength by 15 % compared to the pristine cube and arrested the leaching of residual uranium. The GOA addition and associated enhancement in compressive strength help to save cement and lower CO2 emissions. In short, the present work addresses the critical challenges of using GOA in pre-concentrating and recovering aqueous uranium, such as bulk production, production cost, and spent materials disposal.

Enhanced wound healing of ciprofloxacin incorporated PVA/alginate/PAA electrospun nanofibers with antibacterial effects and controlled drug release

Novel polyvinyl alcohol (PVA), alginate (Alg), and polyacrylic acid (PAA) based nanofiber matrix incorporated with ciprofloxacin (Cip) was manufactured via electrospinning. The functional matrix could accelerate wound healing and also prevent infections by a controlled release of ciprofloxacin. Beads were observed in PVA-Cip which disappeared with the addition of Alg and PAA resulting in the thinnest diameter (141 ± 53 nm) and the most uniform surface. The polymers underwent both intermolecular hydrogen and ester bonds via abundant carboxyl and hydroxyl groups trapping ciprofloxacin inside the matrix. The tensile properties of PVA-Alg-PAA-Cip were significantly higher than the other two samples because of the complex intermolecular bonds. Although the glass transition temperatures (Tg) of the samples were similar, the melting temperature (Tm) of PVA-Alg-PAA-Cip was the highest at 339 oC due to stronger intermolecular bonding. Because of the absorbable nature of alginate, PVA-Alg-Cip swelled the most (600%) in different pH conditions. A controlled release was achieved with only 40% release of ciprofloxacin from PVA-Alg-PAA-Cip compared to 70% in the case of PVA-Cip in neutral pH after 24 h. Because of this slow release, all the samples were able to kill both S. aureus and E. coli for at least 7 days with just a single dose of the drug and PVA-Alg-PAA-Cip demonstrated higher bactericidal activity than other samples. The functional polymer matrix could induce faster healing in a murine excisional wound model, unlike the control group. Ciprofloxacin prevented bacterial infection facilitating faster re-epithelialization as observed in hematoxylin and eosin (H&E) and Masson’s trichrome (MT) staining.

Magnetic Persimmon Leaf Composite: Preparation and Application in Magnetic Solid-Phase Extraction of Pesticides in Water Samples.

In recent years, the utilization of biomass materials for the removal and detection of water pollutants has garnered considerable attention. This study introduces, for the first time, the preparation of Fe3O4/persimmon leaf magnetic biomass composites. The magnetic composites were employed in a magnetic solid-phase extraction method, coupled with gas chromatography-electron capture detection (GC-ECD), for the analysis of four pesticides (trifluralin, triadimefon, permethrin, and fenvalerate) in environmental water samples. The innovative magnetic persimmon leaf composites were synthesized by in situ generation of Fe3O4 nanoparticles through coprecipitation and loaded onto persimmon leaves. These composites exhibit superparamagnetism with a saturation magnetization of 12.8 emu g-1, facilitating rapid phase separation using a magnetic field and reducing the extraction time to 10 min. Desorption can be achieved within 30 s by aspirating 20 times, eliminating the need for time-consuming and labor-intensive experimental steps like filtration and centrifugation. The specific surface area of the magnetic composite adsorbent increased from 1.3279 m2 g-1 for the original persimmon leaf to 5.4688 m2 g-1. The abundant hydroxyl and carboxyl groups on the composites provide ample adsorption sites, resulting in adsorption capacities ranging from 55.056 mg g-1 to 73.095 mg g-1 for the studied pesticides. The composites exhibited extraction recoveries ranging from 80% to 90% for the studied pesticides. Compared to certain previously reported MSPE methods, this approach achieves equivalent or higher extraction recoveries in a shorter operation time, demonstrating enhanced efficiency and convenience. Good linearity of the target analytes was obtained within the range of 0.75-1500 μg L-1, with a determination of coefficient (R2) greater than 0.999. These findings contribute to the use of magnetic persimmon leaf biomass materials as effective and environmentally friendly adsorbents for pollutant determination in water samples.

Integrated Three-Dimensional Microdevice with a Modified Surface for Enhanced DNA Separation from Biological Samples.

Functional interfaces and devices for rapid adsorption and immobilization of nucleic acids (NAs) are significant for relevant bioengineering applications. Herein, a microdevice with poly(acrylic acid) (PAA) photosensitive resin was integrated by three-dimensional (3D) printing, named DPAA for short. Precise microscale structures and abundant surface carboxyl functional groups were fabricated for fast and high-throughput deoxyribonucleic acid (DNA) separation. Surface modification was then done using polydopamine (PDA) and poly(ethylene glycol) (PEG) to obtain modified poly(acrylic acid) (PAA)-based devices DPDA-PAA and DPEG-PAA rich in amino and hydroxyl groups, respectively. The fabricated device DPAA possessed superior printing accuracy (40-50 μm). Functionalization of amino and hydroxyl was successful, and the modified devices DPDA-PAA and DPEG-PAA maintained a high thermal stability like DPAA. Surface potential analysis and molecular dynamics simulation indicated that the affinity for DNA was in the order of DPDA-PAA > DPEG-PAA > DPAA. Further DNA separation experiments confirmed the high throughput and high selectivity of DNA separation performance, consistent with the predicted affinity results. DPDA-PAA showed relatively the highest DNA extraction yield, while DPEG-PAA was the worst. An acidic binding system is more favorable for DNA separation and recovery. DPDA-PAA showed significantly better DNA extraction performance than DPAA in a weakly acidic environment (pH 5.0-7.0), and the average DNA yield of the first elution was 2.16 times that of DPAA. This work validates the possibility of modification on integrated 3D microdevices to improve their DNA separation efficiency effectively. It also provides a new direction for the rational design and functionalization of bioengineering separators based on nonmagnetic methods. It may pave a new path for the highly efficient polymerase chain reaction diagnosis.

Ultrahighly Sensitive and Selective Glutathione Sensor Based on Carbon Dot-Functionalized Solution-Gate Graphene Transistor.

A new type of carbon dot (CD)-functionalized solution-gated graphene transistor (SGGT) sensor was designed and fabricated for the highly sensitive and highly selective detection of glutathione (GSH). The CDs were synthesized via a one-step hydrothermal method using DL-thioctic acid and triethylenetetramine (TETA) as sources of S, N, and C. The CDs have abundant amino and carboxyl groups and were used to modify the surface of the gate electrode of SGGT as probes for detecting GSH. Remarkably, the CDs-SGGT sensor exhibited excellent selectivity and ultrahigh sensitivity to GSH, with an ultralow limit of detection (LOD) of up to 10-19 M. To the best of our knowledge, the sensor outperforms previously reported systems. Moreover, the CDs-SGGT sensor shows rapid detection and good stability. More importantly, the detection of GSH in artificial serum samples was successfully demonstrated.

Cellulose Nanofiber-Alginate Biotemplated Cobalt Composite Multifunctional Aerogels for Energy Storage Electrodes.

Tunable porous composite materials to control metal and metal oxide functionalization, conductivity, pore structure, electrolyte mass transport, mechanical strength, specific surface area, and magneto-responsiveness are critical for a broad range of energy storage, catalysis, and sensing applications. Biotemplated transition metal composite aerogels present a materials approach to address this need. To demonstrate a solution-based synthesis method to develop cobalt and cobalt oxide aerogels for high surface area multifunctional energy storage electrodes, carboxymethyl cellulose nanofibers (CNF) and alginate biopolymers were mixed to form hydrogels to serve as biotemplates for cobalt nanoparticle formation via the chemical reduction of cobalt salt solutions. The CNF-alginate mixture forms a physically entangled, interpenetrating hydrogel, combining the properties of both biopolymers for monolith shape and pore size control and abundant carboxyl groups that bind metal ions to facilitate biotemplating. The CNF-alginate hydrogels were equilibrated in CaCl2 and CoCl2 salt solutions for hydrogel ionic crosslinking and the prepositioning of transition metal ions, respectively. The salt equilibrated hydrogels were chemically reduced with NaBH4, rinsed, solvent exchanged in ethanol, and supercritically dried with CO2 to form aerogels with a specific surface area of 228 m2/g. The resulting aerogels were pyrolyzed in N2 gas and thermally annealed in air to form Co and Co3O4 porous composite electrodes, respectively. The multifunctional composite aerogel's mechanical, magnetic, and electrochemical functionality was characterized. The coercivity and specific magnetic saturation of the pyrolyzed aerogels were 312 Oe and 114 emu/gCo, respectively. The elastic moduli of the supercritically dried, pyrolyzed, and thermally oxidized aerogels were 0.58, 1.1, and 14.3 MPa, respectively. The electrochemical testing of the pyrolyzed and thermally oxidized aerogels in 1 M KOH resulted in specific capacitances of 650 F/g and 349 F/g, respectively. The rapidly synthesized, low-cost, hydrogel-based synthesis for tunable transition metal multifunctional composite aerogels is envisioned for a wide range of porous metal electrodes to address energy storage, catalysis, and sensing applications.

Modulating covalent organic frameworks with accessible carboxyl to boost superior extraction of polar nitrobenzene compounds from matrix-complicated beverages.

The wide use and high polarity of nitrobenzene compounds (NBCs) have caused a concern for their residues in daily beverages. Herein, the covalent organic frameworks (COFs) with abundant carboxyl were ingeniously designed by introducing a novel modulator, and further developed as solid phase microextraction (SPME) coatings. Due to the enhanced polar interaction, the extraction efficiencies of modified COF for NBCs were sharply increased. After coupling the high-performance SPME fiber with gas chromatograph-mass spectrometry (GC-MS), an ultrasensitive analytical method was developed, with a wide linear range (0.50-5000ng/L), and low limits of detection (0.15-3.0ng/L). More importantly, the method was highly feasible and practical, leading to the precise determinations of trace NBCs from variously matrix-complicated samples. This work provides a viable and efficacious approach for the extraction and analysis of polar pollutants form complicated matrices, and is of great significance for mild COF modification and its extended applications in analytical chemistry.