Scalable Production of Biodegradable, Recyclable, Sustainable Cellulose-Mineral Foams via Coordination Interaction Assisted Ambient Drying.

Heavy reliance on petrochemical-based plastic foams in both industry and society has led to severe plastic pollution (the so-called "white pollution"). In this work, we develop a biodegradable, recyclable, and sustainable cellulose/bentonite (Cel/BT) foam material directly from resource-abundant natural materials (i.e., lignocellulosic biomass and minerals) via ambient drying. The strong resistance to the capillary force-driven structural collapse of the preformed three-dimensional (3D) network during the ambient drying process can be ascribed to the purpose-designed cellulose-bentonite coordination interaction, which provides a practical way for the locally scalable production of foam materials with designed shapes without complex processing and intensive energy consumption. Benefiting from the strong cellulose-bentonite coordination interaction, the Cel/BT foam material demonstrates high mechanical strength and outstanding thermal stability, outperforming commercial plastic polystyrene foam. Furthermore, the Cel/BT foam presents environmental impacts much lower than those of petrochemical-based plastic foams as it can be 100% recycled in a closed-loop recycling process and easily biodegraded in the environment (natural cellulose goes back to the carbon cycle, and bentonite minerals return to the geological cycle). This study demonstrates an energy-efficient ambient drying approach for the local and scalable production of an all-natural cellulose/bentonite foam for sustainable packaging, buildings, and beyond, presenting great potential in response to "white pollution" and resource shortage.

[HONO Observation and Assessment of the Effects of Atmospheric Oxidation Capacity in Changzhou During the Springtime of 2017].

HONO measurement was conducted using a wet-chemistry-based method at the Changzhou Environmental Monitoring Center in April 2017. HONO ranged from 0.2-13.9 µg·m-3 with an average of (2.9±2.3) µg·m-3. O3, HCHO, volatile organic compounds, photolysis frequency, and meteorological parameters were simultaneously monitored.·OH concentration was simulated by a Master Chemical Mechanism box model and the daytime maximum·OH concentration ranged from 1.0×106 to 14×106 molecules per cubic centimeter. The formation rates of·OH by photolysis of HONO, O3, HCHO, H2O2, and alkene ozonolysis were calculated as well. The effects of the five sources on atmospheric oxidation capacity were revealed:O3 photolysis (46.4%) > HONO photolysis (41.1%) > alkene ozonolysis (10.9%) > HCHO photolysis (1.5%) > H2O2 photolysis (0.1%). HONO photolysis for OH radical production played a major role in the early morning, before with an increase in O3 concentration, O3 photolysis began to account for most of the·OH production. After 17:00, due to a significant decrease in the intensity of solar radiation, the alkene ozonolysis started playing a major role in the formation of·OH. The photolysis of formaldehyde and hydrogen peroxide played a negligible role in·OH radical production in this study.

[Characterization, Seasonal Variation, and Source Apportionments of Particulate Amines (PM2.5) in Northern Suburb of Nanjing].

PM2.5 samples were collected from December 2017 to November 2018 at a northern suburb site of Nanjing. The concentrations of five amines, major water-soluble ions, organic carbon, and elemental carbon were determined. The five amines measured were methylamine, ethylamine, dimethylamine, trimethylamine, and aniline. The annual average of the total amine concentration was (54.2±29.2) ng·m-3. Among these, dimethylamine was the most abundant[annual average:(20.2±13.7) ng·m-3], followed by methylamine[annual average:(13.1±6.3) ng·m-3], trimethylamine[annual average:(8.6±4.1) ng·m-3], ethylamine[annual average:(6.3±4.1) ng·m-3], and aniline[annual average:(5.9±3.9) ng·m-3]. The total amine concentration showed explicit seasonal variations:summer > autumn > spring > winter. The amine concentration on polluted days was higher than that on clean days. This may be influenced by aerosol acidity, promoting the partitioning of gaseous amine into the particulate phase. Aerosol acidity was also the major reason for the higher concentration of amine observed in summer than in other seasons. During new particle formation events, the concentrations of amines increased substantially. Positive matrix factorization (PMF) was utilized to identify the potential sources of amines, identifying six sources:industrial emission, agriculture emission, biomass burning, automobile emission, secondary formation, and dust. Methylamine and ethylamine mainly originated from secondary formation and automobile emissions. Dimethylamine and trimethylamine mainly originated from biomass burning, secondary formation, and automobile emissions; Aniline mainly originated from industrial emissions and biomass burning. A significant seasonal difference is observed with respect to the sources of amines. In spring and autumn, road dust sources account for a relatively high proportion. In summer, secondary sources are the main sources of amines. However, the diurnal variations of amine are not evident, and the secondary source, motor vehicle emission, and biomass combustion are the three main influencing factors.

Catechol-Based Capacitor for Redox-Linked Bioelectronics.

A common bioelectronics goal is to enable communication between biology and electronics, and success is critically dependent on the communication modality. When a biorelevant modality aligns with instrumentation capabilities, remarkable successes have been observed (e.g., electrodes provide a powerful tool to observe and actuate biology through its ion-based electrical modality). Emerging biological research demonstrates that redox is another biologically relevant modality, and recent research has shown that advanced electrochemical methods enable biodevice communication through this redox modality. Here, we briefly summarize the biological relevance of this redox modality and the use of redox mediators to enable access to this modality through electrochemical measurements. Next, we describe the fabrication of a catechol-chitosan redox capacitor that is redox-active but nonconducting and thus offers a unique set of molecular electronic properties that enhance access to redox-based information. Finally, we cite several recent studies that demonstrate the broad potential for this capacitor to access redox-based biological information. In summary, we envision the redox capacitor will become a vital component in the integrated circuitry of redox-linked bioelectronics.

Catechol-chitosan redox capacitor for added amplification in electrochemical immunoanalysis.

Antibodies are common recognition elements for molecular detection but often the signals generated by their stoichiometric binding must be amplified to enhance sensitivity. Here, we report that an electrode coated with a catechol-chitosan redox capacitor can amplify the electrochemical signal generated from an alkaline phosphatase (AP) linked immunoassay. Specifically, the AP product p-aminophenol (PAP) undergoes redox-cycling in the redox capacitor to generate amplified oxidation currents. We estimate an 8-fold amplification associated with this redox-cycling in the capacitor (compared to detection by a bare electrode). Importantly, this capacitor-based amplification is generic and can be coupled to existing amplification approaches based on enzyme-linked catalysis or magnetic nanoparticle-based collection/concentration. Thus, the capacitor should enhance sensitivities in conventional immunoassays and also provide chemical to electrical signal transduction for emerging applications in molecular communication.

Electrical Programming of Soft Matter: Using Temporally Varying Electrical Inputs To Spatially Control Self Assembly.

The growing importance of hydrogels in translational medicine has stimulated the development of top-down fabrication methods, yet often these methods lack the capabilities to generate the complex matrix architectures observed in biology. Here we show that temporally varying electrical signals can cue a self-assembling polysaccharide to controllably form a hydrogel with complex internal patterns. Evidence from theory and experiment indicate that internal structure emerges through a subtle interplay between the electrical current that triggers self-assembly and the electrical potential (or electric field) that recruits and appears to orient the polysaccharide chains at the growing gel front. These studies demonstrate that short sequences (minutes) of low-power (∼1 V) electrical inputs can provide the program to guide self-assembly that yields hydrogels with stable, complex, and spatially varying structure and properties.

Electro-molecular Assembly: Electrical Writing of Information into an Erasable Polysaccharide Medium.

We report that information can be written into an erasable hydrogel medium by precisely imposing controlled electrical signals that trigger supramolecular self-assembly. We prepare the medium from a blend of two stimuli-responsive self-assembling polysaccharides agarose (thermally responsive) and chitosan (pH-responsive). Upon cooling the blend, agarose forms the hydrogel medium while the embedded chitosan chains can be induced to self-assemble in response to imposed pH cues. Importantly, these triggering pH-cues can be imposed electrically (by inserted electrodes) enabling complex messages (e.g., self-assembled multilayers) to be written within the hydrogel medium. The reversibility of these self-assembly mechanisms allow the written information, and the medium itself, to be erased. These physicochemical properties enable this dual responsive medium to encrypt information, while the responsiveness of this structural information and the biocompatibility of the medium suggest uses for accessing/reporting information in diverse life science applications, such as foods, cosmetics, medicine, and the environment.

[Recent progress of potential effects and mechanisms of chlorogenic acid and its intestinal metabolites on central nervous system diseases].

Chlorogenic acid displays several important roles in the therapeutic properties of many herbs, such as antioxidant activity, antibacterial, antiviral, scavenging free radicals and exciting central nervous system. Only about one-third of chlorogenic acid was absorbed in its prototype, therefore, its gut metabolites play a more important role in the therapeutic properties of chlorogenic acid. It is necessary to consider not only the bioactivities of chlorogenic acid but also its gut metabolites. This review focuses on the potential activities and mechanisms of chlorogenic acid and its gut metabolites on central nervous system diseases.

Coding for hydrogel organization through signal guided self-assembly.

Complex structured soft matter may have important applications in the field of tissue engineering and biomedicine. However, the discovery of facile methods to exquisitely manipulate the structure of soft matter remains a challenge. In this report, a multilayer hydrogel is fabricated from the stimuli-responsive aminopolysaccharide chitosan by using spatially localized and temporally controlled sequences of electrical signals. By programming the imposed cathodic input signals, chitosan hydrogels with varying layer number and thickness can be fabricated. The inputs of electrical signals induce the formation of hydrogel layers while short interruptions create interfaces between each layer. The thickness of each layer is controlled by the charge transfer (Q = ∫idt) during the individual deposition step and the number of multilayers is controlled by the number of interruptions. Scanning electron micrographs (SEMs) reveal organized fibrous structures within each layer that are demarcated by compact orthogonal interlayer structures. This work demonstrates for the first time that an imposed sequence of electrical inputs can trigger the self-assembly of multilayered hydrogels and thus suggests the broader potential for creating an electrical "code" to generate complex structures in soft matter.

Compartmentalized multilayer hydrogel formation using a stimulus-responsive self-assembling polysaccharide.

Polymeric systems that self-assemble through strong noncovalent bonds form structures that are highly dependent on the spatiotemporal sequence of cues that trigger self-assembly. Here, we prepared capsules with a semipermeable alginate-chitosan polyelectrolyte membrane that encapsulates a solution of the pH-responsive self-assembling aminopolysaccharide chitosan. Immersion of these capsules in a basic solution triggers gelation of the capsule contents, and the details of the gel-inducing treatment dramatically affect the final structure of the gelled compartment. Specifically, we show that the sequential transfer of the capsules between the base and water can generate multilayer hydrogel structures, with the thickness of each layer being controlled by the base concentration and immersion times. We further demonstrate that these multilayer hydrogels can serve as templates for the synthesis of iron oxide particles with a complex internal structure (i.e., with a multilayer internal structure). This work demonstrates the ability to enlist the stimulus-responsive self-assembling properties of biological polymers to create materials with complex structures.

Protein addressing on patterned microchip by coupling chitosan electrodeposition and 'electro-click' chemistry.

Many applications in proteomics and lab-on-chip analysis require methods that guide proteins to assemble at surfaces with high spatial and temporal control. Electrical inputs are particularly convenient to control, and there has been considerable effort to discover simple and generic mechanisms that allow electrical inputs to trigger protein assembly on-demand. Here, we report the electroaddressing of a protein to a patterned surface by coupling two generic electroaddressing mechanisms. First, we electrodeposit the stimuli-responsive film-forming aminopolysaccharide chitosan to form a hydrogel matrix at the electrode surface. After deposition, the matrix is chemically functionalized with alkyne groups. Second, we ''electro-click' an azide-tagged protein to the functionalized matrix using electrical signals to trigger conjugation by Huisgen 1,3-dipolar cycloadditions. Specifically, a cathodic potential is applied to the matrix-coated electrode to reduce Cu(II) to Cu(I) which is required for the click reaction. Using fluorescently-labeled bovine serum albumin as our model, we demonstrate that protein conjugation can be controlled spatially and temporally. We anticipate that the coupling of polysaccharide electrodeposition and electro-click chemistry will provide a simple and generic approach to electroaddress proteins within compatible hydrogel matrices.

Chitosan-coated wires: conferring electrical properties to chitosan fibers.

There is considerable interest in creating convenient biosensing platforms that couple the capabilities of biology for selective detection with the power of electronics for signal transduction. Here, the capabilities of a polymeric fiber for facile biofunctionalization is coupled with the signal transduction capabilities of a conducting wire to generate a hybrid platform that can be viewed as either a biofunctionalized wire or a conducting fiber. Integral to this hybrid platform is the interface material chitosan that enables simple electrical signals to be employed to biofunctionalize conducting wires. Specifically, we use cathodic signals to direct chitosan to electrodeposit onto gold wires and anodic signals to conjugate proteins (e.g., for biosensing) to the chitosan-coated wire. In addition, the chitosan-coating is permeable to small molecules, which allows for the electrical detection of electrochemically active compounds that are either present in the external environment or generated by a biofunctionalized chitosan coating. The capabilities for biofunctionalization and transduction are demonstrated for the detection of glucose by chitosan-coated wires functionalized with the enzyme glucose oxidase. Chitosan-coated wires (or alternatively conducting chitosan fibers) are a simple platform that may permit multiplexed biosensing outside the laboratory.

Biofabrication of antibodies and antigens via IgG-binding domain engineered with activatable pentatyrosine pro-tag.

We report the assembly of seven different antibodies (and two antigens) into functional supramolecular structures that are specifically designed to facilitate integration into devices using entirely biologically based bottom-up fabrication. This is enabled by the creation of an engineered IgG-binding domain (HG3T) with an N-terminal hexahistidine tag that facilitates purification and a C-terminal enzyme-activatable pentatyrosine "pro-tag" that facilitates covalent coupling to the pH stimuli-responsive polysaccharide, chitosan. Because we confer pH-stimuli responsiveness to the IgG-binding domain, it can be electrodeposited or otherwise assembled into many configurations. Importantly, we demonstrate the loading of both HG3T and antibodies can be achieved in a linear fashion so that quantitative assessment of antibodies and antigens is feasible. Our demonstration formats include: conventional multiwell plates, micropatterned electrodes, and fiber networks. We believe biologically based fabrication (i.e., biofabrication) provides bottom-up hierarchical assembly of a variety of nanoscale components for applications that range from point-of-care diagnostics to smart fabrics.

Orthogonal enzymatic reactions for the assembly of proteins at electrode addresses.

The ability to interface proteins to device surfaces is important for a range of applications. Here, we enlist the unique capabilities of enzymes and biologically derived polymers to assemble target proteins to electrode addresses. First, the stimuli-responsive aminopolysaccharide chitosan is directed to assemble at the electrode address in response to electrode-imposed signals. The electrodeposited chitosan film serves as the biodevice interface for subsequent protein assembly. Next, tyrosinase is used to catalyze grafting of a protein or peptide tether to the chitosan film. Finally, microbial transglutaminase (mTG) catalyzes the assembly of target proteins to the tether. mTG covalently links proteins through their glutamine (Gln) and lysine (Lys) residues. Since Gln and Lys residues of globular proteins are often inaccessible to mTG, we engineered our target proteins to have fusion tags with added Gln or Lys residues. This assembly method employs the electrical signal to confer spatial selectivity (during chitosan electrodeposition) and employs the enzymes to confer chemical selectivity (i.e., amino acid residue selectivity). Further, this method is mild, since no reactive reagents or protection steps are required, and all steps are performed in aqueous solution. These results demonstrate the potential for employing biological materials and mechanisms to biofabricate the biodevice interface.

Chitosan fibers: versatile platform for nickel-mediated protein assembly.

Fibers are a versatile platform because standard methods are available for the hierarchical assembly of individual fibers into controllable patterns (e.g., fabrics). Here, we report a method to biofunctionalize individual fibers by the reversible binding of proteins, and we suggest the potential of fiber assemblies by generating simple multifiber structures. Specifically, we use chitosan fibers and show that nickel can mediate assembly of histidine-tagged proteins to these fibers. Initial studies with the model His-GFP demonstrate the concept of nickel-mediated protein assembly. Subsequent studies with a His-tagged streptococcal antibody-binding protein (protein G) demonstrate the assembly of antibodies to generate antibody-presenting fibers. Antibody assembly onto the fiber was shown to be controllable, and antigen-binding to these antibody-presenting fibers was measured. Importantly, antibody and antigen were observed to penetrate substantially into the individual fibers (tens of microns) to allow the assembly of pmole levels of protein per cm of fiber length. Finally, antibody-presenting fibers with different specificities were assembled into simple one- and two-dimensional structures, and individual fibers in these fiber assemblies were observed to capture their respective antigens from antigen mixtures. The potential of fiber assemblies for multiplexed analysis is discussed.

Chitosan biotinylation and electrodeposition for selective protein assembly.

An alternative route to protein assembly at surfaces based on using the unique capabilities of biological materials for the spatially selective assembly of proteins is described. Specifically, the stimuli-responsive properties of aminopolysaccharide chitosan are combined with the molecular-recognition capabilities of biotin-streptavidin binding. Biotinylated chitosan retains its stimuli-responsive properties and is capable of electrodepositing at specific electrode addresses. Once deposited, it is capable of binding streptavidin, which can mediate the subsequent assembly of biotinylated proteins. Spatially selective protein assembly using biotinylated Protein A and fluorescently-labeled antibodies is demonstrated.

Quaternized chitosan/alginate nanoparticles for protein delivery.

Quaternized chitosan (QCS)/alginate (AL) nanoparticles (QCS/AL) were successfully prepared in neutral condition for the oral delivery of protein. The physicochemical structure of the QCS/AL nanoparticles was characterized by IR spectroscopy and transmission electron microscopy. The diameter of the nanoparticles with a positive surface charge was about 200 nm. The load of bovine serum albumin (BSA) was affected by the concentration and the molecular parameters, i.e. degree of substitution (DS) and weight-average molecular weight (Mw) of QCS, as well as the concentration of BSA. The release of BSA from nanoparticles was pH-dependent. Quick release occurred in 0.1M phosphate buffer solution (PBS, pH=7.4), while the release was slow in 0.1M HCl (pH=1.2). The DS and Mw of QCS play important roles in the release of BSA in vitro. QCS with high Mw accelerated the release of BSA in acid, while high DS retarded the release of BSA in both 0.1M HCl and 0.1M PBS.

Chitosan nanoparticle as gene therapy vector via gastrointestinal mucosa administration: results of an in vitro and in vivo study.

This study was designed to investigate the in vitro and in vivo transfection efficiency of chitosan nanoparticles used as vectors for gene therapy. Three types of chitosan nanoparticles [quaternized chitosan -60% trimethylated chitosan oligomer (TMCO-60%), C(43-45 KDa, 87%), and C(230 KDa, 90%)] were used to encapsulate plasmid DNA (pDNA) encoding green fluorescent protein (GFP) using the complex coacervation technique. The morphology, optimal chitosan-pDNA binding ratio and conditions for maximal in vitro transfection were studied. The in vivo transfection was conducted by feeding the chitosan/pDNA nanoparticles to 12 BALB/C-nu/nu nude mice. Both conventional and TMCO-60% could form stable nanoparticles with pDNA. The in vitro study showed the transfection efficiency to be in the following descending order: TMCO-60%>C(43-45 KDa, 87%)>C(230 KDa, 90%). TMCO-60% proved to be the most efficient and the optimal chitosan/pDNA ratio being 3.2:1. In vivo study showed most prominent GPF expression in the gastric and upper intestinal mucosa. GFP expression in the mucosa of the stomach and duodenum, jejunum, ileum, and large intestine were found, respectively, in 100%, 88.9%, 77.8% and 66.7% of the nude mice examined. TMCO-60%/pDNA nanoparticles had better in vitro and in vivo transfection activity than the other two, and with minimal toxicity, which made it a desirable non-viral vector for gene therapy via oral administration.

Ionically crosslinked alginate/carboxymethyl chitin beads for oral delivery of protein drugs.

Complex beads composed of alginate and carboxymethyl chitin (CMCT) were prepared by dropping aqueous alginate-CMCT into an iron(III) solution. The structure and morphology of the beads were characterized by IR spectroscopy and scanning electron microscopy (SEM). IR confirmed electrostatic interactions between iron(III) and the carboxyl groups of alginate as well as CMCT, and the binding model was suggested as a three-dimensional structure. SEM revealed that CMCT had a porous morphology while alginate and their complex beads had a core-layer structure. The swelling behavior, encapsulation efficiency, and release behavior of bovine serum albumin (BSA) from the beads at different pHs were investigated. The BSA encapsulation efficiency was fairly high (>90%). It was found that CMCT disintegrated at pH 1.2 and alginate eroded at pH 7.4 while the complex beads could effectively retain BSA in acid (>85%) and reduce the BSA release at pH 7.4. The results suggested that the iron(III)-alginate-CMCT bead could be a suitable polymeric carrier for site-specific protein drug delivery in the intestine.