Chitosan-Sulfated Titania Composite Membranes with Potential Applications in Fuel Cell: Influence of Cross-Linker Nature

Humelnicu, Andra-Cristina; Samoilă, Petrişor; Asăndulesa, Mihai; Cojocaru, Corneliu; Bele, Adrian; Marinoiu, Adriana; Saccà, A.; Harabagiu, Valeria

doi:10.3390/polym12051125

Cited by 17 publications

(11 citation statements)

References 43 publications

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“…A band between 1222 cm −1 to 1100 cm −1 are assigned to the S=O group which indicates the existence of sulphate species. Besides, the bands between 1057 and 994 cm −1 was attributed to symmetry and asymmetry stretching of the S-O bond [17,48] has obtained a similar observation, where the S-O bands are assigned to chelating bidentate SO 4 2− in coordination with Ti 4+ metal. Therefore, the experimental result of the FTIR spectrum shows that the relative functional group present in synthesized catalysts indicates the sulfation has successfully occurred in this study. )…”

Section: Physicochemical Properties Of the Synthesized Catalystmentioning

confidence: 59%

Assessment on the Effect of Sulfuric Acid Concentration on Physicochemical Properties of Sulfated-Titania Catalyst and Glycerol Acetylation Performance

et al. 2021

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In this research, a solid acid catalyst was synthesized to catalyse glycerol acetylation into acetins. The sulphated-titania catalysts were prepared via the wet impregnation method at different sulfuric acid concentrations (5%, 10%, 15%, and 20%) and denoted as 5SA, 10SA, 15SA, and 20SA, respectively. The synthesized catalysts were characterized using FTIR, XRD, TGA, BET, NH3-TPD, XRF, and SEM-EDX. The synthesized catalysts were tested on glycerol acetylation reaction at conditions: 0.5 g catalyst loading, 100–120 °C temperature, 1:6 glycerol/acetic acid molar ratios, and 2–4 h reaction time. The final product obtained was analysed using GC-FID. An increment in sulfuric acid concentration reduces the surface area, pore volume, and particles size. However, the increment has increased the number of active sites (Lewis acid) and strong acid strength. 15SA catalyst exhibited excellent glycerol conversion (>90%) and the highest selectivity of triacetin (42%). Besides sufficient surface area (1.9 m2 g−1) and good porosity structure, the great performance of the 15SA catalyst was attributed to its high acid site density (342.6 µmol g−1) and the high active site of metal oxide (95%).

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Section: Physicochemical Properties Of the Synthesized Catalystmentioning

confidence: 59%

Assessment on the Effect of Sulfuric Acid Concentration on Physicochemical Properties of Sulfated-Titania Catalyst and Glycerol Acetylation Performance

et al. 2021

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“…Chitosan (CS), with an average molar mass of 290 kDa and 81.6% deacetylation degree (as previously determined by viscometry, respectively by NMR analysis [19]) was provided by Merck Chemical (Saint Louis, MO, USA). L-(+)-Lactic acid (LA) and anhydrous glycerin (Gly) were purchased from Chemical Company (Ias , i, Romania).…”

Section: Methodsmentioning

confidence: 99%

Chitosan-Based Therapeutic Systems for Superficial Candidiasis Treatment. Synergetic Activity of Nystatin and Propolis

Humelnicu¹,

Samoilă²,

Cojocaru³

et al. 2022

Polymers

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The paper deals with new approaches to chitosan (CS)-based antifungal therapeutic formulations designed to fulfill the requirements of specific applications. Gel-like formulations were prepared by mixing CS dissolved in aqueous lactic acid (LA) solution with nystatin (NYS) powder and/or propolis (PRO) aqueous solution dispersed in glycerin, followed by water evaporation to yield flexible mesoporous (pore widths of 2–4 nm) films of high specific surfaces between 1 × 103 and 1.7 × 103 m2/g. Morphological evaluation of the antifungal films showed uniform dispersion and downsizing of NYS crystallites (with initial sizes up to 50 μm). Their mechanical properties were found to be close to those of soft tissues (Young’s modulus values between 0.044–0.025 MPa). The films presented hydration capacities in physiological condition depending on their composition, i.e., higher for NYS-charged (628%), as compared with PRO loaded films (118–129%). All NYS charged films presented a quick release for the first 10 min followed by a progressive increase of the release efficiency at 48.6%, for the samples containing NYS alone and decreasing values with increasing amount of PRO to 45.9% and 42.8% after 5 h. By in vitro analysis, the hydrogels with acidic pH values around 3.8 were proven to be active against Candida albicans and Candida glabrata species. The time-killing assay performed during 24 h on Candida albicans in synthetic vagina-simulative medium showed that the hydrogel formulations containing both NYS and PRO presented the faster slowing down of the fungal growth, from colony-forming unit (CFU)/mL of 1.24 × 107 to CFU/mL < 10 (starting from the first 6 h).

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“…Chitosan (CS) with properties previously determined (degree of deacetylation of 81.6% and viscosimetric average molar mass of 290 kDa) [ 50 ], 1,3-bis(3-glycidyloxypropyl)tetramethyldisiloxane ≥ 95.0% (DS) and succinic anhydride (SA) were purchased from Merck Chemical (Saint Louis, MO, USA) and used as received.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of Physically and/or Chemically Modified Chitosan Hydrogels for Proficient Release of Insoluble Nystatin in Simulated Fluids

Enache¹,

Cojocaru²,

Samoilă³

et al. 2022

Gels

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To avoid fungal spreading in the bloodstream and internal organs, many research efforts concentrate on finding appropriate candidiasis treatment from the initial stage. This paper proposes chitosan-based physically or chemically cross-linked hydrogels aimed to provide sustained release of micronized nystatin (NYSm) antifungal drug, known for its large activity spectrum. Nystatin was demonstrated itself to provide hydrodynamic/mechanic stability to the chitosan hydrogel through hydrophobic interactions and H-bonds. For chemical cross-linking of the succinylated chitosan, a non-toxic diepoxy-functionalized siloxane compound was used. The chemical structure and composition of the hydrogels, also their morphology, were evidenced by infrared spectroscopy (FTIR), by energy dispersive X-ray (EDX) analysis and by scanning electron microscopy (SEM), respectively. The hydrogels presented mechanical properties which mimic those of the soft tissues (elastic moduli < 1 MPa), necessary to ensure matrix accommodation and bioadhesion. Maximum swelling capacities were reached by the hydrogels with higher succinic anhydride content at both pH 7.4 (429%) and pH 4.2 (471%), while higher amounts of nystatin released in the simulative immersion media (57% in acidic pH and 51% in pH 7.4) occurred from the physical cross-linked hydrogel. The release mechanism by non-swellable matrix diffusion and the susceptibility of three Candida strains make all the hydrogel formulations effective for NYSm local delivery and for combating fungal infections.

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Chitosan-Sulfated Titania Composite Membranes with Potential Applications in Fuel Cell: Influence of Cross-Linker Nature

Cited by 17 publications

References 43 publications

Assessment on the Effect of Sulfuric Acid Concentration on Physicochemical Properties of Sulfated-Titania Catalyst and Glycerol Acetylation Performance

Assessment on the Effect of Sulfuric Acid Concentration on Physicochemical Properties of Sulfated-Titania Catalyst and Glycerol Acetylation Performance

Chitosan-Based Therapeutic Systems for Superficial Candidiasis Treatment. Synergetic Activity of Nystatin and Propolis

Evaluation of Physically and/or Chemically Modified Chitosan Hydrogels for Proficient Release of Insoluble Nystatin in Simulated Fluids

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