Polymers

Research

15 pages, 4179 KiB

Open AccessArticle

Emulsion Stabilization Strategies for Tailored Isocyanate Microcapsules

by Mónica V. Loureiro, António Mariquito, Mário Vale, João C. Bordado, Isabel Pinho and Ana C. Marques

Polymers 2023, 15(2), 403; https://doi.org/10.3390/polym15020403 - 12 Jan 2023

Cited by 5 | Viewed by 3533

Abstract

We report on the stabilization of an oil-in-water (O/W) emulsion to, combined with interfacial polymerization, produce core–shell polyurea microcapsules (MCs) containing isophorone diisocyanate (IPDI). These will act as crosslinkers for mono-component adhesives. The emulsion stabilization was evaluated using three types of stabilizers, a [...] Read more.

We report on the stabilization of an oil-in-water (O/W) emulsion to, combined with interfacial polymerization, produce core–shell polyurea microcapsules (MCs) containing isophorone diisocyanate (IPDI). These will act as crosslinkers for mono-component adhesives. The emulsion stabilization was evaluated using three types of stabilizers, a polysaccharide (gum arabic) emulsifier, a silicone surfactant (Dabco^®DC193), a rheology modifier (polyvinyl alcohol), and their combinations. Emulsion sedimentation studies, optical microscopy observation, and scanning electron microscopy enabled us to assess the emulsions stability and droplet size distribution and correlate them to the MCs morphology. Fourier transform infrared spectroscopy and thermogravimetric analysis revealed the MCs composition and enabled us to evaluate the encapsulation yield. All stabilizers, except DC193, led to spherical, loose, and core–shelled MCs. The rheology modifier, which increases the continuous phase viscosity, reduces the emulsion droplets sedimentation, keeping their size constant during the MCs’ synthesis. This allowed us to obtain good quality MCs, with a smaller average diameter, of approximately 40.9 µm mode, a narrower size distribution and 46 wt% of encapsulated IPDI. We show the importance of the emulsion stability to tune the MCs morphology, size, and size distribution, which are critical for improved homogeneity and performance when used, e.g., in natural and synthetic adhesive formulations industry. Full article

(This article belongs to the Special Issue Polymer-Based Nano/Microparticles)

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12 pages, 2384 KiB

Open AccessArticle

Evaluation of Biopolymer Materials and Synthesis Techniques to Develop a Rod-Shaped Biopolymer Surrogate for Legionella pneumophila

by Sujani Ariyadasa, Weiam Daear, Gayan Abeysekera, Craig Billington, Conan Fee, Elmar Prenner and Liping Pang

Polymers 2022, 14(13), 2571; https://doi.org/10.3390/polym14132571 - 24 Jun 2022

Cited by 3 | Viewed by 2063

Abstract

Biopolymer microparticles have been developed for applications that require biocompatibility and biodegradability, such as drug delivery. In this study, we assessed the production of microparticles using carnauba wax, κ-carrageenan, alginate, and poly (lactic-co-glycolic acid) (PLGA) with the aim of developing a novel, DNA-tracer-loaded, [...] Read more.

Biopolymer microparticles have been developed for applications that require biocompatibility and biodegradability, such as drug delivery. In this study, we assessed the production of microparticles using carnauba wax, κ-carrageenan, alginate, and poly (lactic-co-glycolic acid) (PLGA) with the aim of developing a novel, DNA-tracer-loaded, biopolymer surrogate with a size, shape, surface charge, and relative hydrophobicity similar to stationary-phase Legionella pneumophila to mimic the bacteria’s mobility and persistence in engineered water systems. We found that the type and concentration of biopolymer, reaction conditions, and synthesis methods affected the morphology, surface charge, relative hydrophobicity, and DNA tracer loading efficiency of the biopolymer microparticles produced. Carnauba wax, κ-carrageenan, and alginate (Protanal^®, and low and medium viscosity) produced highly polydisperse microspheres. In contrast, PLGA and alginate-CaCO₃ produced uniform microspheres and rod-shaped microparticles, respectively, with high DNA tracer loading efficiencies (PLGA 70% and alginate-CaCO₃ 95.2 ± 5.7%) and high reproducibilities. Their synthesis reproducibility was relatively high. The relative hydrophobicity of PLGA microspheres closely matched the cell surface hydrophobicity of L. pneumophila but not the bacterial morphology, whereas the polyelectrolyte layer-by-layer assembly was required to enhance the relative hydrophobicity of alginate-CaCO₃ microparticles. Following this surface modification, alginate-CaCO₃ microparticles represented the best match to L. pneumophila in size, morphology, surface charge, and relative hydrophobicity. This new biopolymer surrogate has the potential to be used as a mimic to study the mobility and persistence of L. pneumophila in water systems where the use of the pathogen is impractical and unsafe. Full article

(This article belongs to the Special Issue Polymer-Based Nano/Microparticles)

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25 pages, 8652 KiB

Open AccessArticle

The Microencapsulation of Tung Oil with a Natural Hydrocolloid Emulsifier for Extrinsic Self-Healing Applications

by Abdullah Naseer Mustapha, Maitha AlMheiri, Nujood AlShehhi, Nitul Rajput, Sachin Joshi, Ana Antunes and Mohamed AlTeneiji

Polymers 2022, 14(9), 1907; https://doi.org/10.3390/polym14091907 - 7 May 2022

Cited by 6 | Viewed by 3477

Abstract

In this work, tung oil was utilised as a catalyst-free self-healing agent, and an in-situ polymerization process was applied to encapsulate the tung oil core with a poly(urea-formaldehyde) (PUF) shell. The conventional poly(ethylene-alt-maleic-anhydride) (PEMA) polymer was compared to a more naturally abundant gelatin [...] Read more.

In this work, tung oil was utilised as a catalyst-free self-healing agent, and an in-situ polymerization process was applied to encapsulate the tung oil core with a poly(urea-formaldehyde) (PUF) shell. The conventional poly(ethylene-alt-maleic-anhydride) (PEMA) polymer was compared to a more naturally abundant gelatin (GEL) emulsifier to compare the microcapsules’ barrier, morphological, thermal, and chemical properties, and the crystalline nature of the shell material. GEL emulsifiers produced microcapsules with a higher payload (96.5%), yield (28.9%), and encapsulation efficiency (61.7%) compared to PEMA (90.8%, 28.6% and 52.6%, respectively). Optical and electron microscopy imaging indicated a more uniform morphology for the GEL samples. The thermal decomposition measurements indicated that GEL decomposed to a value 7% lower than that of PEMA, which was suggested to be attributed to the much thinner shell materials that the GEL samples produced. An innovative and novel focused ion beam (FIB) milling method was exerted on the GEL sample, confirming the storage and release of the active tung oil material upon rupturing. The samples with GEL conveyed a higher healing efficiency of 91%, compared to PEMA’s 63%, and the GEL samples also conveyed higher levels of corrosion resistance. Full article

(This article belongs to the Special Issue Polymer-Based Nano/Microparticles)

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12 pages, 2763 KiB

Open AccessArticle

Nanoparticle-Doped Hybrid Polyelectrolyte Microcapsules with Controlled Photoluminescence for Potential Bioimaging Applications

by Galina Nifontova, Victor Krivenkov, Mariya Zvaigzne, Anton Efimov, Evgeny Korostylev, Sergei Zarubin, Alexander Karaulov, Igor Nabiev and Alyona Sukhanova

Polymers 2021, 13(23), 4076; https://doi.org/10.3390/polym13234076 - 24 Nov 2021

Cited by 3 | Viewed by 2846

Abstract

Fluorescent imaging is widely used in the diagnosis and tracking of the distribution, interaction, and transformation processes at molecular, cellular, and tissue levels. To be detectable, delivery systems should exhibit a strong and bright fluorescence. Quantum dots (QDs) are highly photostable fluorescent semiconductor [...] Read more.

Fluorescent imaging is widely used in the diagnosis and tracking of the distribution, interaction, and transformation processes at molecular, cellular, and tissue levels. To be detectable, delivery systems should exhibit a strong and bright fluorescence. Quantum dots (QDs) are highly photostable fluorescent semiconductor nanocrystals with wide absorption spectra and narrow, size-tunable emission spectra, which make them suitable fluorescent nanolabels to be embedded into microparticles used as bioimaging and theranostic agents. The layer-by-layer deposition approach allows the entrapping of QDs, resulting in bright fluorescent microcapsules with tunable surface charge, size, rigidity, and functional properties. Here, we report on the engineering and validation of the structural and photoluminescent characteristics of nanoparticle-doped hybrid microcapsules assembled by the deposition of alternating oppositely charged polyelectrolytes, water-soluble PEGylated core/shell QDs with a cadmium selenide core and a zinc sulfide shell (CdSe/ZnS), and carboxylated magnetic nanoparticles (MNPs) onto calcium carbonate microtemplates. The results demonstrate the efficiency of the layer-by-layer approach to designing QD-, MNP-doped microcapsules with controlled photoluminescence properties, and pave the way for the further development of next-generation bioimaging agents based on hybrid materials for continuous fluorescence imaging. Full article

(This article belongs to the Special Issue Polymer-Based Nano/Microparticles)

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16 pages, 2996 KiB

Open AccessArticle

Characterization, Bioactivity and Application of Chitosan-Based Nanoparticles in a Food Emulsion Model

by Karina Oliveira Lima, Cristian Mauricio Barreto Pinilla, Ailén Alemán, M. Elvira López-Caballero, M. Carmen Gómez-Guillén, Pilar Montero and Carlos Prentice

Polymers 2021, 13(19), 3331; https://doi.org/10.3390/polym13193331 - 29 Sep 2021

Cited by 20 | Viewed by 3054

Abstract

In this study, chitosan nanoparticles (CNPs) were prepared by the ionic gelation technique with tripolyphosphate (TPP), and the effect of CNP composition and physicochemical characteristics were evaluated. After the synthesis optimization, CNPs were used as carriers for a fish protein hydrolysate (FPH) with [...] Read more.

In this study, chitosan nanoparticles (CNPs) were prepared by the ionic gelation technique with tripolyphosphate (TPP), and the effect of CNP composition and physicochemical characteristics were evaluated. After the synthesis optimization, CNPs were used as carriers for a fish protein hydrolysate (FPH) with bioactive properties (CNPH). The physicochemical characteristics, antioxidant capacity and antimicrobial, antihypertensive and emulsifier properties of unloaded and loaded CNPs in a food system model were studied. CNPH showed a uniform particle distribution, size ~200 nm, high stability (zeta potential around 30 mV), radical scavenging activity and increased antimicrobial activity against Staphylococcus aureus, Shigella sonnei and Aeromonas hydrophila. Additionally, CNPH showed an angiotensin I-converting enzyme (ACE)-inhibitory activity of 63.6% and, when added to a food emulsion model, this system containing CNPs, with or without FHP, exhibited improved food emulsion stability. Thus, CNPs were able to carry the FPH while maintaining their bioactive properties and can be an alternative to the delivery of bioactive peptides with potential as an emulsion stabilizer for food applications. Full article

(This article belongs to the Special Issue Polymer-Based Nano/Microparticles)

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18 pages, 3347 KiB

Open AccessArticle

Fabrication and Characterization of Cinnamaldehyde-Loaded Mesoporous Bioactive Glass Nanoparticles/PHBV-Based Microspheres for Preventing Bacterial Infection and Promoting Bone Tissue Regeneration

by Kittipat Chotchindakun, Jeeraporn Pekkoh, Jetsada Ruangsuriya, Kai Zheng, Irem Unalan and Aldo R. Boccaccini

Polymers 2021, 13(11), 1794; https://doi.org/10.3390/polym13111794 - 29 May 2021

Cited by 31 | Viewed by 4466

Abstract

Polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is considered a suitable polymer for drug delivery systems and bone tissue engineering due to its biocompatibility and biodegradability. However, the lack of bioactivity and antibacterial activity hinders its biomedical applications. In this study, mesoporous bioactive glass nanoparticles (MBGN) were incorporated [...] Read more.

Polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is considered a suitable polymer for drug delivery systems and bone tissue engineering due to its biocompatibility and biodegradability. However, the lack of bioactivity and antibacterial activity hinders its biomedical applications. In this study, mesoporous bioactive glass nanoparticles (MBGN) were incorporated into PHBV to enhance its bioactivity, while cinnamaldehyde (CIN) was loaded in MBGN to introduce antimicrobial activity. The blank (PHBV/MBGN) and the CIN-loaded microspheres (PHBV/MBGN/CIN5, PHBV/MBGN/CIN10, and PHBV/MBGN/CIN20) were fabricated by emulsion solvent extraction/evaporation method. The average particle size and zeta potential of all samples were investigated, as well as the morphology of all samples evaluated by scanning electron microscopy. PHBV/MBGN/CIN5, PHBV/MBGN/CIN10, and PHBV/MBGN/CIN20 significantly exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli in the first 3 h, while CIN releasing behavior was observed up to 7 d. Human osteosarcoma cell (MG-63) proliferation and attachment were noticed after 24 h cell culture, demonstrating no adverse effects due to the presence of microspheres. Additionally, the rapid formation of hydroxyapatite on the composite microspheres after immersion in simulated body fluid (SBF) during 7 d revealed the bioactivity of the composite microspheres. Our findings indicate that this system represents an alternative model for an antibacterial biomaterial for potential applications in bone tissue engineering. Full article

(This article belongs to the Special Issue Polymer-Based Nano/Microparticles)

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18 pages, 5422 KiB

Open AccessArticle

Enhanced Cytotoxic Activity of Docetaxel-Loaded Silk Fibroin Nanoparticles against Breast Cancer Cells

by Ahmed Al Saqr, Shahid Ud Din Wani, H. V. Gangadharappa, Mohammed F. Aldawsari, El-Sayed Khafagy and Amr S. Abu Lila

Polymers 2021, 13(9), 1416; https://doi.org/10.3390/polym13091416 - 27 Apr 2021

Cited by 34 | Viewed by 3922

Abstract

Despite decades of research, breast cancer therapy remains a great challenge. Docetaxel is an antimicrotubule agent that is effectively used for the treatment of breast cancer. However, its clinical use is significantly hampered by its low water solubility and systemic toxicity. The current [...] Read more.

Despite decades of research, breast cancer therapy remains a great challenge. Docetaxel is an antimicrotubule agent that is effectively used for the treatment of breast cancer. However, its clinical use is significantly hampered by its low water solubility and systemic toxicity. The current study was designed to prepare docetaxel (DXL)-loaded silk-fibroin-based nanoparticles (SF-NPs) and to screen their potential antitumor activity against breast cancer cell lines. DXL-loaded SF-NPs were prepared using a nanoprecipitation technique and were evaluated for particle size, zeta potential, entrapment efficiency, and in vitro release profile. In addition, DXL-loaded SF-NPs were screened for in vitro cytotoxicity, cellular uptake, and apoptotic potential against MCF-7 and MDA-MB-231 breast cancer cell lines. The prepared DXL-loaded SF-NPs were 178 to 198 nm in diameter with a net negative surface charge and entrapment efficiency ranging from 56% to 72%. In vitro release studies exhibited a biphasic release profile of DXL from SF-NPs with sustained drug release for 72 h. In vitro cell studies revealed that entrapment of DXL within SF-NPs significantly improved cytotoxic potential against breast cancer cell lines, compared to the free drug, and enhanced cellular uptake of DXL by breast cancer cells. Furthermore, the accumulation in the G2/M phase was significantly higher in cells treated with DXL-loaded SF-NPs than in cells treated with free DXL. Collectively, the superior antitumor activities of DXL-loaded SF-NPs against breast cancer cells, compared to free DXL, could be ascribed to improved apoptosis and cell cycle arrest. Our results highlighted the feasibility of using silk fibroin nanoparticles as a nontoxic biocompatible delivery vehicle for enhanced therapeutic outcomes in breast cancer. Full article

(This article belongs to the Special Issue Polymer-Based Nano/Microparticles)

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15 pages, 5219 KiB

Open AccessArticle

Properties and Characterization of New Approach Organic Nanoparticle-Based Biocomposite Board

by I. Ismail, Arliyani, Z. Jalil, Mursal, N. G. Olaiya, C. K. Abdullah, M. R. N. Fazita and H. P. S. Abdul Khalil

Polymers 2020, 12(10), 2236; https://doi.org/10.3390/polym12102236 - 28 Sep 2020

Cited by 9 | Viewed by 4725

Abstract

Conventionally, panel boards are produced with material flex or microparticle with P.U. or U.F. as adhesives. However, in this study, nanoparticle with epoxy resin as an adhesive was used to produce nanoboard. Coconut shell nanoparticle composite with epoxy resin as an adhesive was [...] Read more.

Conventionally, panel boards are produced with material flex or microparticle with P.U. or U.F. as adhesives. However, in this study, nanoparticle with epoxy resin as an adhesive was used to produce nanoboard. Coconut shell nanoparticle composite with epoxy resin as an adhesive was prepared using a compression molding technique. The coconut shell particles were originally 200 mesh size and then milled mechanically with a ball mill for the duration of 10, 20, 30, and 40 h (milling times) to produce nanoparticles. The composition ratio of the composite is 85 vol.% of coconut shell and 15 vol.% of epoxy resin. The formation of nanoparticles was observed with transmission electron microscopy (TEM). The mechanical, physical, and microstructure properties of the composite were examined with X-ray diffraction, scanning electron microscopy, atomic force microscopy, and universal testing machine. The results established that the properties of the composite (microstructures, mechanical, and physical) are influenced by the duration of milling of coconut shell particles. The modulus and flexural strength of the composite improved with an increase in the milling time. The density, thickness swelling, and porosity of the composite were also influenced by the milling times. The result suggested that the composite properties were influenced by the particle size of the coconut shell. The coconut shell nanoparticle composite can be used in the manufacturing of hybrid panels and board. Full article

(This article belongs to the Special Issue Polymer-Based Nano/Microparticles)

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