A method to assemble stimuli-responsive nucleic acid-based hydrogel-stabilized microcapsule-in-microcapsule systems is introduced. An inner aqueous compartment stabilized by a stimuli-responsive ...hydrogel-layer (∼150 nm) provides the inner microcapsule (diameter ∼2.5 μm). The inner microcapsule is separated from an outer aqueous compartment stabilized by an outer stimuli-responsive hydrogel layer (thickness of ∼150 nm) that yields the microcapsule-in-microcapsule system. Different loads, e.g., tetramethyl rhodamine-dextran (TMR-D) and CdSe/ZnS quantum dots (QDs), are loaded in the inner and outer aqueous compartments. The hydrogel layers exist in a higher stiffness state that prevents inter-reservoir or leakage of the loads from the respective aqueous compartments. Subjecting the inner hydrogel layer to Zn
-ions and/or the outer hydrogel layer to acidic pH or crown ether leads to the triggered separation of the bridging units associated with the respective hydrogel layers. This results in the hydrogel layers of lower stiffness allowing either the mixing of the loads occupying the two aqueous compartments, the guided release of the load from the outer aqueous compartment, or the release of the loads from the two aqueous compartments. In addition, a pH-responsive microcapsule-in-microcapsule system is loaded with glucose oxidase (GOx) in the inner aqueous compartment and insulin in the outer aqueous compartment. Glucose permeates across the two hydrogel layers resulting in the GOx catalyzed aerobic oxidation of glucose to gluconic acid. The acidification of the microcapsule-in-microcapsule system leads to the triggered unlocking of the outer, pH-responsive hydrogel layer and to the release of insulin. The pH-stimulated release of insulin is controlled by the concentration of glucose. While at normal glucose levels, the release of insulin is practically prohibited, the dose-controlled release of insulin in the entire diabetic range is demonstrated. Also, switchable ON/OFF release of insulin is achieved highlighting an autonomous glucose-responsive microdevice operating as an "artificial pancreas" for the release of insulin.
Marine natural products Blunt, John W; Copp, Brent R; Keyzers, Robert A ...
Natural product reports,
02/2015, Volume:
32, Issue:
2
Journal Article
Peer reviewed
Open access
This review covers the literature published in 2013 for marine natural products (MNPs), with 982 citations (644 for the period January to December 2013) referring to compounds isolated from marine ...microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1163 for 2013), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.
Graphene oxide (GO) crosslinked nanocomposites hydrogels (NCH) of chitosan (CS) and carboxymethyl cellulose (CMC) were synthesized and the feasibility of its application as a versatile adsorbent for ...the remediation of cationic (methylene blue, MB) as well as anionic (methyl orange, MO) dyes contaminated wastewater was explored. Initially, GO was functionalized with vinyltriethoxysilane which was subsequently used as a chemical crosslinker to synthesize the NCH of CS and CMC (CS/CMC-NCH) with the polymeric mixture of diallyldimethylammonium chloride and 2-acrylamido-2-methyl-1-propanesulfonic acid. About 99% dye was adsorbed from 50 mg/L dye solution of MB dye with 0.4 g/L of CS/CMC-NCH at pH 7, whereas, for MO about 82% dye was adsorbed with 0.6 g/L of CS/CMC-NCH at pH 3. The Adsorption of both dyes is well explained using pseudo-second-order and Langmuir models with the maximum adsorption capacities of 655.98 mgdye/gads for MB and 404.52 mgdye/gads for MO. Thermodynamics studies suggested spontaneous and exothermic nature of the adsorption process with values of ΔS < 0 and ΔH > 0. Furthermore, CS/CMC-NCH showed excellent regeneration capacity for continuous twenty cycles of adsorption-desorption. Therefore, the synthesized CS/CMC-NCH is a versatile adsorbent that can treat both anionic and cationic dyes contaminated wastewater.
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•GO-VTES crosslinked NCH of chitosan and carboxymethyl cellulose were synthesized.•CS/CMC-NCH adsorbed methylene blue and methyl orange dyes.•Adsorption process was expressed with Langmuir and pseudo-second-order models.•Thermodynamic parameters showed the spontaneous and exothermic adsorption.•Regeneration studies indicated the high reuse efficiency upto twenty cycles.
The design of slippery liquid‐infused porous surfaces (SLIPS) using nanoporous and chemically reactive polymer multilayers is reported. This approach permits fabrication of slippery anti‐fouling ...coatings on complex surfaces and provides new means to manipulate the mobilities of contacting aqueous fluids. The results expand the range of tools that can be used to manipulate the behaviors of SLIPS and open the door to new applications of this emerging class of soft materials.
The fruits of Chinese hawthorn (Crataegus pinnatifida) have been used as the functional food and folk medicine due to potent antioxidant activity. In this study, polyphenols were extracted from the ...fruits of Chinese hawthorn and further added into chitosan-gelatin blend films to develop active packaging. The microstructure, physical, mechanical, barrier and antioxidant properties of the films were investigated in details. Results showed epicatechin, chlorogenic acid and procyanidin B2 were the main polyphenols in the extract of hawthorn fruits. The inner microstructure of chitosan-gelatin blend films became more compact when the extract was incorporated. The intermolecular interactions between film matrix and the extract were through hydrogen bonding and electrostatic interactions. The incorporation of the extract remarkably increased the thickness, tensile strength and elongation at break of chitosan-gelatin blend films. However, the moisture content, water vapor permeability and light transmittance of chitosan-gelatin blend films were significantly reduced by the addition of the extract. Moreover, chitosan-gelatin blend films containing the extract exhibited potent free radical scavenging ability. Our results suggest Chinese hawthorn fruit extract can be used as a natural antioxidant to improve the mechanical, barrier and antioxidant properties of chitosan-gelatin blend films.
•Chinese hawthorn fruit extract was added into chitosan-gelatin blend films.•Film matrix interacted with extract via hydrogen bond and electrostatic interactions.•The extract addition enhanced the mechanical and barrier properties of the films.•Films containing the extract showed dose-dependent free radical scavenging ability.
•Physicochemical and Mechanical properties of chitosan-gelatin based films containing Quercetin-starch (Q) were investigated.•Quercetin-starch improved antioxidant property as well as antibacterial ...property.•Ch-ge-Q films protected foods from UV radiation.•Quercetin-starch improved mechanical properties of the film as well as WVP.
Ecofriendly chitosan-gelatin (Ch-ge) bio-composite films containing Quercetin-starch (Q) were synthesized using solution casting method. Physicochemical characteristics and mechanical properties of the resulting chitosan-gelatin containing Quercetin-starch films (Ch-ge-Q) were studied using UV, FTIR, XRD and SEM techniques. The films were also investigated for their swelling, water-vapor permeability (WVP), water solubility properties. The FTIR spectra confirmed the chemical interactions between the chitosan-gelatin and Q. Surface morphology of prepared film was analyzed by the SEM imaging while XRD spectra suggest the expanded crystallinity of the film with the addition of Q. The film also showed enhanced barrier property against UV rays. The reduction of water-vapor permeability and increase in tensile strength while a decrease in elongation at break has been observed in the Ch-ge-Q film compared to Ch-ge film. The antibacterial activity of Ch-ge-Q film against both gram positive (B. substilis) and gram negative (E. coli) bacteria suggested the Q loaded Ch-ge films as more feasible antibacterial candidate especially against the strain E. coli. The antioxidant activity of the Ch-ge-Q film was evaluated using the DPPH and ABTS as standards and corresponded to 81.45% of DPPH and 72.2% of ABTS scavenging activities. It was observed that the film containing Quercetin-starch presented superior antioxidant activity results in comparison to Ch-ge film promising its application in food packaging.
DNA nanotechnology enables engineering of molecular-scale devices with exquisite control over geometry and site-specific functionalization. This capability promises compelling advantages in advancing ...nanomedicine; nevertheless, instability in biological environments and innate immune activation remain as obstacles for in vivo application. Natural particle systems (i.e., viruses) have evolved mechanisms to maintain structural integrity and avoid immune recognition during infection, including encapsulation of their genome and protein capsid shell in a lipid envelope. Here we introduce virus-inspired enveloped DNA nanostructures as a design strategy for biomedical applications. Achieving a high yield of tightly wrapped unilamellar nanostructures, mimicking the morphology of enveloped virus particles, required precise control over the density of attached lipid conjugates and was achieved at 1 per ∼180 nm2. Envelopment of DNA nanostructures in PEGylated lipid bilayers conferred protection against nuclease digestion. Immune activation was decreased 2 orders of magnitude below controls, and pharmacokinetic bioavailability improved by a factor of 17. By establishing a design strategy suitable for biomedical applications, we have provided a platform for the engineering of sophisticated, translation-ready DNA nanodevices.
The increasing acceptance of ready to eat food generates demand on development of active and intelligent food packaging material. Even though many polymers have been used for the packaging, they have ...limitations for broad applications. Among the various polymers, Poly Vinyl Alcohol is a promising film forming polymer with highly flexible, emulsifying and adhesive properties. A variety of nano-fabrication techniques have already been reported to improve the mechanical and antimicrobial properties of PVA to exploit its wider applications. In the present study, starch-PVA based composite films incorporated with zinc oxide nanoparticles and phytochemicals were prepared by solvent casting technique. The films were characterized by XRD, FT-IR, UV–Vis spectrometry and SEM. The developed nanocomposite films were demonstrated to have enhanced water barrier, mechanical and antimicrobial properties. The unique features of the nanocomposite with its pH indication property demonstrated in the study indicate its potential usage in food packaging applications.
•pH sensing antimicrobial wraps were prepared and characterized.•Films were found to be water resistant with excellent UV-light barrier properties.•Microbial barrier ability also makes it suitable for packaging foods.
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