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  • 1
    Online Resource
    Online Resource
    New Mesoporous Silica Materials Loaded with Polyphenols: Caffeic Acid, Ferulic Acid and p-Coumaric Acid as Dietary Supplements for Oral Administration
    MDPI AG ; 2022
    In:  Materials Vol. 15, No. 22 ( 2022-11-11), p. 7982-
    Details
    In: Materials, MDPI AG, Vol. 15, No. 22 ( 2022-11-11), p. 7982-
    Abstract: In this study, two types of mesoporous silica with different pore structures and volumes were synthesized by the soft-templating method. The two types of mesoporous silica, type MCM-41 and MCM-48, were loaded with three polyphenols—caffeic acid, p-coumaric acid and trans-ferulic acid—in the same ratio of mesoporous silica:polyphenol (1:0.4 w/w). The materials obtained were characterized from a morphological and structural point of view through different analysis techniques. Through X-ray diffraction (XRD), the crystallization plane and the ordered structure of the mesoporous silica were observed. The difference between the two types of materials containing MCM-41 and MCM-48 was observed through the different morphologies of the silica particles through scanning electron microscopy (SEM) and also through the Brunauer–Emmet–Teller (BET) analysis, that the surface areas and volumes of pores was different between the two types of mesoporous silica, and, after loading with polyphenols, the values were reduced. The characteristic bands of silica and of polyphenols were easily observed by Fourier-transform infrared spectroscopy (FTIR), and, through thermogravimetric analysis (TGA), the residual mass was determined and the estimated amount of polyphenol in the materials and the efficient loading of mesoporous silica with polyphenols could be determined. The in vitro study was performed in two types of simulated biological fluids with different pH—simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). The obtained materials could be used in various biomedical applications as systems with controlled release of natural polyphenols and the most suitable application could be as food supplements especially when a mixture of such materials is used or when the polyphenols are co-loaded within the mesoporous silica.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma15227982
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2487261-1
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  • 2
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    Online Resource
    Antibacterial Activity of Solvothermal Obtained ZnO Nanoparticles with Different Morphology and Photocatalytic Activity against a Dye Mixture: Methylene Blue, Rhodamine B and Methyl Orange
    MDPI AG ; 2023
    In:  International Journal of Molecular Sciences Vol. 24, No. 6 ( 2023-03-16), p. 5677-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 24, No. 6 ( 2023-03-16), p. 5677-
    Abstract: In this paper, we report the synthesis of ZnO nanoparticles (NPs) by forced solvolysis of Zn(CH3COO)2·2H2O in alcohols with a different number of –OH groups. We study the influence of alcohol type (n-butanol, ethylene glycol and glycerin) on the size, morphology, and properties of the obtained ZnO NPs. The smallest polyhedral ZnO NPs ( 〈 30 nm) were obtained in n-butanol, while in ethylene glycol the NPs measured on average 44 nm and were rounded. Polycrystalline particles of 120 nm were obtained in glycerin only after water refluxing. In addition, here, we report the photocatalytic activity, against a dye mixture, of three model pollutants: methyl orange (MO), methylene blue (MB), and rhodamine B (RhB), a model closer to real situations where water is polluted with many chemicals. All samples exhibited good photocatalytic activity against the dye mixture, with degradation efficiency reaching 99.99%. The sample with smallest nanoparticles maintained a high efficiency 〉 90%, over five catalytic cycles. Antibacterial tests were conducted against Gram-negative strains Salmonella enterica serovar Typhimurium, Pseudomonas aeruginosa, and Escherichia coli, and Gram-positive strains Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, and Bacillus cereus. The ZnO samples presented strong inhibition of planktonic growth for all tested strains, indicating that they can be used for antibacterial applications, such as water purification.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms24065677
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 3
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    Magneto-Mechanically Triggered Thick Films for Drug Delivery Micropumps
    MDPI AG ; 2022
    In:  Nanomaterials Vol. 12, No. 20 ( 2022-10-13), p. 3598-
    Details
    In: Nanomaterials, MDPI AG, Vol. 12, No. 20 ( 2022-10-13), p. 3598-
    Abstract: Given the demanding use of controlled drug delivery systems, our attention was focused on developing a magnetic film that can be triggered in the presence of a magnetic field for both drug delivery and the actuating mechanism in micropump biomedical microelectromechanical systems (BioMEMS). Magnetic alginate films were fabricated in three steps: the co-precipitation of iron salts in an alkaline environment to obtain magnetite nanoparticles (Fe3O4), the mixing of the obtained nanoparticles with a sodium alginate solution containing glycerol as a plasticizer and folic acid as an active substance, and finally the casting of the final solution in a Petri dish followed by cross-linking with calcium chloride solution. Magnetite nanoparticles were incorporated in the alginate matrix because of the well-established biocompatibility of both materials, a property that would make the film convenient for implantable BioMEMS devices. The obtained film was analyzed in terms of its magnetic, structural, and morphological properties. To demonstrate the hypothesis that the magnetic field can be used to trigger drug release from the films, we studied the release profile in an aqueous medium (pH = 8) using a NdFeB magnet as a triggering factor.
    Type of Medium: Online Resource
    ISSN: 2079-4991
    URL: Article
    DOI: 10.3390/nano12203598
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2662255-5
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  • 4
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    Antibacterial Biodegradable Films Based on Alginate with Silver Nanoparticles and Lemongrass Essential Oil–Innovative Packaging for Cheese
    MDPI AG ; 2021
    In:  Nanomaterials Vol. 11, No. 9 ( 2021-09-13), p. 2377-
    Details
    In: Nanomaterials, MDPI AG, Vol. 11, No. 9 ( 2021-09-13), p. 2377-
    Abstract: Replacing the petroleum-based materials in the food industry is one of the main objectives of the scientists and decision makers worldwide. Biodegradable packaging will help diminish the environmental impact of human activity. Improving such biodegradable packaging materials by adding antimicrobial activity will not only extend the shelf life of foodstuff, but will also eliminate some health hazards associated with food borne diseases, and by diminishing the food spoilage will decrease the food waste. The objective of this research was to obtain innovative antibacterial films based on a biodegradable polymer, namely alginate. Films were characterized by environmental scanning electron microscopy (ESEM), Fourier-transform infrared spectroscopy (FTIR) and microscopy, complex thermal analysis (TG-DSC-FTIR), UV-Vis and fluorescence spectroscopy. Water vapor permeability and swelling behavior were also determined. As antimicrobial agents, we used silver spherical nanoparticles (Ag NPs) and lemongrass essential oil (LGO), which were found to act in a synergic way. The obtained films exhibited strong antibacterial activity against tested strains, two Gram-positive (Bacillus cereus and Staphylococcus aureus) and two Gram-negative (Escherichia coli and Salmonella Typhi). Best results were obtained against Bacillus cereus. The tests indicate that the antimicrobial films can be used as packaging, preserving the color, surface texture, and softness of cheese for 14 days. At the same time, the color of the films changed (darkened) as a function of temperature and light presence, a feature that can be used to monitor the storage conditions for sensitive food.
    Type of Medium: Online Resource
    ISSN: 2079-4991
    URL: Article
    DOI: 10.3390/nano11092377
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2662255-5
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  • 5
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    Online Resource
    Synergistic Antimicrobial Activity of Magnetite and Vancomycin-Loaded Mesoporous Silica Embedded in Alginate Films
    MDPI AG ; 2023
    In:  Gels Vol. 9, No. 4 ( 2023-04-02), p. 295-
    Details
    In: Gels, MDPI AG, Vol. 9, No. 4 ( 2023-04-02), p. 295-
    Abstract: The aim of the present study was to obtain a hydrogel-based film as a carrier for the sustained and controlled release of vancomycin, an antibiotic commonly used in various types of infections. Considering the high-water solubility of vancomycin ( 〉 50 mg/mL) and the aqueous medium underlying the exudates, a prolonged release of vancomycin from an MCM-41 carrier was sought. The present work focused on the synthesis of malic acid coated magnetite (Fe3O4/malic) by co-precipitation, synthesis of MCM-41 by a sol-gel method and loading of MCM-41 with vancomycin, and their use in alginate films for wound dressing. The nanoparticles obtained were physically mixed and embedded in the alginate gel. Prior to incorporation, the nanoparticles were characterized by XRD, FT-IR and FT-Raman spectroscopy, TGA-DSC and DLS. The films were prepared by a simple casting method and were further cross-linked and examined for possible heterogeneities by means of FT-IR microscopy and SEM. The degree of swelling and the water vapor transmission rate were determined, considering their potential use as wound dressings. The obtained films show morpho-structural homogeneity, sustained release over 48 h and a strong synergistic enhancement of the antimicrobial activity as a consequence of the hybrid nature of these films. The antimicrobial efficacy was tested against S. aureus, two strains of E. faecalis (including vancomycin-resistant Enterococcus, VRE) and C. albicans. The incorporation of magnetite was also considered as an external triggering component in case the films were used as a magneto-responsive smart dressing to stimulate vancomycin diffusion.
    Type of Medium: Online Resource
    ISSN: 2310-2861
    URL: Article
    DOI: 10.3390/gels9040295
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2813982-3
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  • 6
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    Online Resource
    A Comparative Loading and Release Study of Vancomycin from a Green Mesoporous Silica
    MDPI AG ; 2022
    In:  Molecules Vol. 27, No. 17 ( 2022-08-30), p. 5589-
    Details
    In: Molecules, MDPI AG, Vol. 27, No. 17 ( 2022-08-30), p. 5589-
    Abstract: Since its first use as a drug delivery system, mesoporous silica has proven to be a surprisingly efficient vehicle due to its porous structure. Unfortunately, most synthesis methods are based on using large amounts of surfactants, which are then removed by solvent extraction or heat treatment, leading to an undesired environmental impact because of the generated by-products. Hence, in the present study, we followed the synthesis of a silica material with a wormhole-like pore arrangement, using two FDA-approved substances as templates, namely Tween-20 and starch. As far as we know, it is the first study using the Tween-20/starch combo as a template for mesoporous silica synthesis. Furthermore, we investigated whether the obtained material using this novel synthesis had any potential in using it as a DDS. The material was further analyzed by XRD, TEM, FT-IR, N2 adsorption/desorption, and DLS to investigate its physicochemical features. Vancomycin was selected as the active molecule based on the extensive research engaged towards improving its bioavailability for oral delivery. The drug was loaded onto the material by using three different approaches, assuming its full retention in the final system. Thermal analysis confirmed the successful loading of vancomycin by all means, and pore volume significantly decreased upon loading, especially in the case of the vacuum-assisted method. All methods showed a slower release rate compared to the same amount of the pure drug. Loadings by physical mixing and solvent evaporation released the whole amount of the drug in 140 min, and the material loaded by the vacuum-assisted method released only 68.2% over the same period of time, leading us to conclude that vancomycin was adsorbed deeper inside the pores. The kinetic release of the three systems followed the Higuchi model for the samples loaded by physical mixing and vacuum-assisted procedures, while the solvent evaporation loading method was in compliance with the first-order model.
    Type of Medium: Online Resource
    ISSN: 1420-3049
    URL: Article
    DOI: 10.3390/molecules27175589
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2008644-1
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  • 7
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    Increasing Bioavailability of Trans-Ferulic Acid by Encapsulation in Functionalized Mesoporous Silica
    MDPI AG ; 2023
    In:  Pharmaceutics Vol. 15, No. 2 ( 2023-02-16), p. 660-
    Details
    In: Pharmaceutics, MDPI AG, Vol. 15, No. 2 ( 2023-02-16), p. 660-
    Abstract: Two types of mesoporous materials, MCM-41 and MCM-48, were functionalized by the soft-template method using (3-aminopropyl)triethoxysilane (APTES) as a modifying agent. The obtained mesoporous silica materials were loaded with trans-ferulic acid (FA). In order to establish the morphology and structure of mesoporous materials, a series of specific techniques were used such as: X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmet-Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). We monitored the in vitro release of the loaded FA at two different pH values, by using simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). Additionally, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Candida albicans ATCC 10231 were used to evaluate the antimicrobial activity of FA loaded mesoporous silica materials. In conclusion such functionalized mesoporous materials can be employed as controlled release systems for polyphenols extracted from natural sources.
    Type of Medium: Online Resource
    ISSN: 1999-4923
    URL: Article
    DOI: 10.3390/pharmaceutics15020660
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2527217-2
    SSG: 15,3
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  • 8
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    Influence of the Alcohols on the ZnO Synthesis and Its Properties: The Photocatalytic and Antimicrobial Activities
    MDPI AG ; 2022
    In:  Pharmaceutics Vol. 14, No. 12 ( 2022-12-18), p. 2842-
    Details
    In: Pharmaceutics, MDPI AG, Vol. 14, No. 12 ( 2022-12-18), p. 2842-
    Abstract: Zinc oxide (ZnO) nanomaterials are used in various health-related applications, from antimicrobial textiles to wound dressing composites and from sunscreens to antimicrobial packaging. Purity, surface defects, size, and morphology of the nanoparticles are the main factors that influence the antimicrobial properties. In this study, we are comparing the properties of the ZnO nanoparticles obtained by solvolysis using a series of alcohols: primary from methanol to 1-hexanol, secondary (2-propanol and 2-butanol), and tertiary (tert-butanol). While the synthesis of ZnO nanoparticles is successfully accomplished in all primary alcohols, the use of secondary or tertiary alcohols does not lead to ZnO as final product, underlining the importance of the used solvent. The shape of the obtained nanoparticles depends on the alcohol used, from quasi-spherical to rods, and consequently, different properties are reported, including photocatalytic and antimicrobial activities. In the photocatalytic study, the ZnO obtained in 1-butanol exhibited the best performance against methylene blue (MB) dye solution, attaining a degradation efficiency of 98.24%. The comparative study among a series of usual model dyes revealed that triarylmethane dyes are less susceptible to photo-degradation. The obtained ZnO nanoparticles present a strong antimicrobial activity on a broad range of microorganisms (bacterial and fungal strains), the size and shape being the important factors. This permits further tailoring for use in medical applications.
    Type of Medium: Online Resource
    ISSN: 1999-4923
    URL: Article
    DOI: 10.3390/pharmaceutics14122842
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2527217-2
    SSG: 15,3
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  • 9
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    Online Resource
    Biodegradable Antimicrobial Food Packaging: Trends and Perspectives
    MDPI AG ; 2020
    In:  Foods Vol. 9, No. 10 ( 2020-10-11), p. 1438-
    Details
    In: Foods, MDPI AG, Vol. 9, No. 10 ( 2020-10-11), p. 1438-
    Abstract: This review presents a perspective on the research trends and solutions from recent years in the domain of antimicrobial packaging materials. The antibacterial, antifungal, and antioxidant activities can be induced by the main polymer used for packaging or by addition of various components from natural agents (bacteriocins, essential oils, natural extracts, etc.) to synthetic agents, both organic and inorganic (Ag, ZnO, TiO2 nanoparticles, synthetic antibiotics etc.). The general trend for the packaging evolution is from the inert and polluting plastic waste to the antimicrobial active, biodegradable or edible, biopolymer film packaging. Like in many domains this transition is an evolution rather than a revolution, and changes are coming in small steps. Changing the public perception and industry focus on the antimicrobial packaging solutions will enhance the shelf life and provide healthier food, thus diminishing the waste of agricultural resources, but will also reduce the plastic pollution generated by humankind as most new polymers used for packaging are from renewable sources and are biodegradable. Polysaccharides (like chitosan, cellulose and derivatives, starch etc.), lipids and proteins (from vegetal or animal origin), and some other specific biopolymers (like polylactic acid or polyvinyl alcohol) have been used as single component or in blends to obtain antimicrobial packaging materials. Where the package’s antimicrobial and antioxidant activities need a larger spectrum or a boost, certain active substances are embedded, encapsulated, coated, grafted into or onto the polymeric film. This review tries to cover the latest updates on the antimicrobial packaging, edible or not, using as support traditional and new polymers, with emphasis on natural compounds.
    Type of Medium: Online Resource
    ISSN: 2304-8158
    URL: Article
    DOI: 10.3390/foods9101438
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2704223-6
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  • 10
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    Innovative Antimicrobial Chitosan/ZnO/Ag NPs/Citronella Essential Oil Nanocomposite—Potential Coating for Grapes
    MDPI AG ; 2020
    In:  Foods Vol. 9, No. 12 ( 2020-12-04), p. 1801-
    Details
    In: Foods, MDPI AG, Vol. 9, No. 12 ( 2020-12-04), p. 1801-
    Abstract: New packaging materials based on biopolymers are gaining increasing attention due to many advantages like biodegradability or existence of renewable sources. Grouping more antimicrobials agents in the same packaging can create a synergic effect, resulting in either a better antimicrobial activity against a wider spectrum of spoilage agents or a lower required quantity of antimicrobials. In the present work, we obtained a biodegradable antimicrobial film that can be used as packaging material for food. Films based on chitosan as biodegradable polymer, with ZnO and Ag nanoparticles as filler/antimicrobial agents were fabricated by a casting method. The nanoparticles were loaded with citronella essential oil (CEO) in order to enhance the antimicrobial activity of the nanocomposite films. The tests made on Gram-positive, Gram-negative, and fungal strains indicated a broad-spectrum antimicrobial activity, with inhibition diameters of over 30 mm for bacterial strains and over 20 mm for fungal strains. The synergic effect was evidenced by comparing the antimicrobial results with chitosan/ZnO/CEO or chitosan/Ag/CEO simple films. According to the literature and our preliminary studies, these formulations are suitable as coating for fruits. The obtained nanocomposite films presented lower water vapor permeability values when compared with the chitosan control film. The samples were characterized by SEM, fluorescence and UV-Vis spectroscopy, FTIR spectroscopy and microscopy, and thermal analysis.
    Type of Medium: Online Resource
    ISSN: 2304-8158
    URL: Article
    DOI: 10.3390/foods9121801
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2704223-6
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