The novel calcium carbonate (CaCO3) morphology, twin-sphere with an equatorial girdle, has been obtained under the control of poly(l-lysine) (PLys) through gas-diffusion method. The effect of the ...concentration of calcium cation and PLys, the reaction time, and the initial pH value are investigated, and various interesting morphologies, including twin-sphere, discus-like, hexagonal plate, and hallow structure are observed by using scanning electronic microscopy. Laser microscopic Raman spectroscopy studies indicated that all these CaCO3 are vaterite. A possible mechanism is suggested to explain the formation of the twin-sphere based morphologies according to the results. It is proven that alkaline polypeptides can control the mineralization of CaCO3 precisely as the reported acidic polypeptides and double hydrophilic block copolymers.
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IJS, KILJ, NUK, PNG, UL, UM
AgBr nanoparticles on boron-doped reduced graphene oxide aerogels (AgBr/B-RGO) are synthesized by a facile hydrothermal method, which shows a superior performance in the photoreduction of toxic ...hexavalent chromium (Cr VI ) in aqueous media under visible light irradiation. The composition and structure of the samples have been characterized by using XPS, Raman, XRD, TEM and SEM measurements. As compared with that of AgBr on none-doped reduced graphene oxide aerogels (AgBr/RGO), the improved photocatalytic properties, can be attributed to the introduction of boron atoms in reduced graphene oxide (RGO), bringing in the improvement of electron transfer efficiency, and the depression of the recombination of photo-excited electrons and holes. Further tests in the photoreduction of Cr VI reveal that the obtained AgBr/B-RGO presents excellent cycling performance with an interesting increase in the photocatalytic efficiency upon cycling number. This observation can be explained by the fact that the gradual emergence of Ag 0 formed from the photo-induced decomposition of AgBr, introduces a Surface Plasmon Resonance (SPR) effect to the system. The approach herein reported could be extended to the design and fabrication of other photocatalysts with high performance that combine the boron-doped graphene and SPR effect.
The grafting of pH-responsive poly(acrylic acid) (PAA) brushes was carried out on the surface of a commercial TFC-PA membrane using surface-initiated atom transfer radical polymerization (SI-ATRP). ...Poly(t-butyl acrylate) was polymerized through the SI-ATRP method followed by its acid hydrolysis to form PAA hydrophilic polymer brushes. Surface morphology, permeation flux, salt rejection, and pore sizes were investigated. The contact angle for water was reduced from 50° for a pristine membrane to 27° for the modified membrane due to a modification with the hydrophilic functional group and its brush on membrane surfaces. The flux rate also increased noticeably at lower pH values relative to higher pH for the modified membranes, while the flux remains stable in the case of pristine TFC-PA membranes. There is slight transition in the water flux rate that was also observed when going from pH values of 3 to 5. This was attributed to the pH-responsive conformational changes for the grafted PAA brushes. At these pH values, ionization of the COOH group takes place below and above pKa to influence the effective pore dimension of the modified membranes. At a lower pH value, the PAA brushes seem to permit tight structure conformation resulting in larger pore sizes and hence more flux. On the other hand, at higher pH values, PAA brushes appeared to be in extended conformation to induce smaller pore sizes and result in less flux. Further, pH values were observed to not significantly affect the NaCl salt rejection with values observed in between 98.8% and 95% and close to that of the pristine TFC-PA membranes. These experimental results are significant and have immediate implication for advances in polymer technology to design and modify the “switchable membrane surfaces” with controllable charge distribution and surface wettability, as well as regulation of water flux and salt.
The design of a delivery system was reported based on stimuli-responsive poly(N-isopropylacrylamide) (PNIPA) inside a mesostructured cellular foam (MCF) via atom transfer radical polymerization ...(ATRP), and the control of drug release in response to the environmental temperature was investigated. The successful synthesis of PNIPA inside the MCF was confirmed by Fourier transform infrared (FT-IR), transmission electron microscopy (TEM) and nitrogen adsorption/desorption measurements. Control of drug release through the porous network was performed by measuring the uptake and release of ibuprofen (IBU). The delivery system of MCF-PNIPA demonstrated a high IBU storage capacity of 58 wt% (IBU/silica), which is much higher than that reported for functional SBA-15 (37 wt%). The multilayer polymers inside the pores of the MCF were considered to form an internal cavity for drug molecules in addition to responding to changes in external temperature.
Nowadays, treating corneal diseases arising from injury to the corneal endothelium necessitates donor tissue, but these corneas are extremely scarce. As a result, researchers are dedicating ...significant efforts to exploring alternative approaches that do not rely on donor tissues. Among these, creating a tissue-engineered scaffold on which corneal endothelial cells can be transplanted holds particular fascination. Numerous functional materials, encompassing natural, semi-synthetic, and synthetic polymers, have already been studied in this regard. In this review, we present a comprehensive overview of recent advancements in using polymer biomaterials as scaffolds for corneal endothelium tissue engineering. Initially, we analyze and present the key properties necessary for an effective corneal endothelial implant utilizing polymer biomaterials. Subsequently, we focus on various emerging biomaterials as scaffolds for corneal endothelium tissue engineering. We discuss their modifications (including natural and synthetic composites) and analyze the effect of micro- and nano-topological morphology on corneal endothelial scaffolds. Lastly, we highlight the challenges and prospects of these materials in corneal endothelium tissue engineering.
A novel responsive carrier system based on ordered mesoporous silica SBA-15 was synthesized, with magnetic particles formed in situ and thermo-sensitive poly(
N-isopropyl acrylamide) (PNIPA) ...polymerized inside the pores. It was interesting to find that the obtained system held a relatively large pore diameter (3.8
nm) and pore volume (0.47
cm
3
g
−1), which would benefit for drug storage with relatively large molecules. The delivery system displayed a hysteresis loop with a saturation magnetization (
M
s) of 0.40
emu/g, which revealed the magnetic property of the prepared system. In vitro test of ibuprofen (IBU) loading and release exhibited a pronounced transition at around 17
°C, indicating a typical thermo-sensitive release property for this delivery system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
An ordered mesoporous carbon material functionalized with carboxylic acid groups was synthesized. It was characterized by powder X-ray diffraction, transmission electron microscopy, Fourier transform ...IR spectroscopy and N₂ adsorption/desorption. Furthermore, this material was used to modify an electrode surface combined with a hydrophobic ionic liquid. The functionalized ordered mesoporous carbon/ionic liquid gel modified electrode shows excellent electrocatalytic performances for the oxidation of dopamine, uric acid and ascorbic acid. The presence of the ionic liquid promotes the electron transfer. Linear responses for dopamine and uric acid were obtained in the ranges of 0.1 to 500 μM and from 0.1 to 100 μM with detection limits of 4.1 and 2.5 nM (signal-to-noise ratio of 3), respectively, under optimum conditions. A quick and sensitive biosensor based on functionalized ordered mesoporous carbon and an ionic liquid has been developed for the first time for the detection of dopamine and uric acid in the presence of a large amount of ascorbic acid. graphic removed
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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► Hybrid hydrogel consisted of C2-symmetric benzene-based gelator and alginate. ► Hybrid hydrogels have favorable mechanical and water retention properties. ► Hybrid hydrogels show ...controlled and sustained release property for certain dyes. ► Hybrid hydrogels were selective for different dyes release.
In this paper, 1,4-bi(phenylalanine-diglycol)-benzene (PDB) based Low-Molecular-Weight-Gelator (LMWG) hydrogels are modified using hydrophilic polysaccharide (sodium alginate). A set of techniques including Fourier transform infrared (FT-IR) spectroscopy, 1H Nuclear Magnetic Resonance (1H NMR), X-ray powder diffraction (XRD), Ultraviolet–Visible (UV–Vis), and circular dichroism (CD) had confirmed a β-turn arrangement of PDB gelators and a semi-interpenetrating network (semi-IPN), which was formed through hydrogen bonds between LMWG fibers and polysaccharide chains. The evaluation of physicochemical properties of hydrogels indicates that gelator-polysaccharide hybrid hydrogels possess better mechanical and water retention properties than LMWG hydrogels. The release study of dyes (model drug) from both LMWG and hybrid hydrogels was carried out. Compared with PDB based hydrogels, hybrid hydrogels show a selective and controllable release property for certain dyes. The results suggest LMWG-polysaccharide hybrid gels may find potential applications as promising drug delivery vehicles for drug molecules.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
▶ A responsive drug delivery system based on poly(N-isopropyl acrylamide) (PNIPAM) functionalized ordered mesoporous carbon (CMK-3) is developed. ▶ A combination of surface modification of CMK-3 and ...in situ internal polymerization of PNIPAM was used. ▶ The system exhibited a pronounced transition at around 20–25
°C.
A novel responsive drug delivery system based on poly(N-isopropyl acrylamide) (PNIPAM) functionalized ordered mesoporous carbon (CMK-3) is developed. The polymer-functionalized CMK-3 was obtained by a combination of simple surface modification of CMK-3 and in situ internal polymerization of PNIPAM. The formation of the PNIPAM inside the CMK-3 was confirmed by thermal gravimetric analysis, Fourier transform-infrared spectroscopy, scanning and transmission electron microscopy and N
2 adsorption/desorption measurements. Controlled drug release tests through the porous network of the PNIPAM functionalized CMK-3 were carried out by measuring the uptake and release of ibuprofen in vitro. The release profiles exhibited a pronounced transition at around 20–25
°C. This thermo-sensitive release property of this delivery system was further confirmed by temperature-variable hydrogen nuclear magnetic resonance analysis. The internal PNIPAM layers acted as a storage gate as well as a release switch in response to the stimuli of environment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Inspired by nature, herein we designed a novel construction of SnO
2
anodes with an extremely high lithium storage performance. By utilizing small sheets of graphene oxide, the ...partitioned-pomegranate-like structure was constructed (SnO
2
@C@half-rGO), in which the porous clusters of SnO
2
nanoparticles are partially supported by reduced graphene oxide sheets while the rest part is exposed (half-supported), like partitioned pomegranates. When served as anode for lithium-ion batteries, SnO
2
@C@half-rGO exhibited considerably high specific capacity (1034.5 mAh g
−1
after 200 cycles at 100 mA g
−1
), superior rate performance and remarkable durability (370.3 mAh g
−1
after 10000 cycles at 5 A g
−1
). When coupled with graphitized porous carbon cathode for lithium-ion hybrid capacitors, the fabricated devices delivered a high energy density of 257 Wh kg
−1
at ∼200 W kg
−1
and maintained 79 Wh kg
−1
at a super-high power density of ∼20 kW kg
−1
within a wide voltage window up to 4 V. This facile and scalable approach demonstrates a new architecture for graphene-based composite for practical use in energy storage with high performance.
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