Preparation of multifunctional polysaccharide microcontainers for lipophilic bioactive agents

Antifungal activity and aroma persistence of free and encapsulated Cinnamomum cassia essential oil in maize

The objective of this study was to evaluate the chemical composition and antifungal activity of free and encapsulated Cinnamomum cassia essential oil (EO) against Penicillium crustosum, Alternaria alternata, and Aspergillus flavus, and the aroma persistence in maize flour. Trans-cinnamaldehyde (TC) was identified as the major compound (86 %) in the C. cassia EO. The EO was encapsulated by spray-dryer with 45.26 % efficiency using gum arabic (GA) and maltodextrin (MD) in a ratio of 1:1 (m/m). C. cassia EO showed antifungal activity against A. alternata, A. flavus, and P. crustosum, with a minimum inhibitory concentration (MIC) of 0.5 % for both free and standard TC, and 5 % for the encapsulated EO. Fungal growth inhibition was evaluated under exposition to vapors at different concentrations of C. cassia EO and TC standard, with MIC of 6 % and 8 % against P. crustosum, 4 % and 1 % A. alternata, and 4 % A. flavus, respectively. The sensory analysis results of the free and encapsulated C. cassia EO in maize flour showed a significant difference between the treated samples in relation to the standard sample (p < 0.05). The sample with free EO has high aroma intensity persistence, while the samples treated with encapsulated EO were evaluated as being closer to the standard sample. The results suggest that the encapsulated C. cassia EOs can be used as natural alternatives to control fungi in maize flour.

Ultrasound-Assisted Encapsulation of Citronella Oil in Alginate/Carrageenan Beads: Characterization and Kinetic Models

The objective of this research was to investigate the effect of ultrasonication on citronella oil encapsulation using alginate/carrageenan (Alg/Carr) in the presence of sodium dodecyl sulfate (SDS). The functional groups of microparticles were characterized using Fourier transform infrared spectroscopy (FTIR), and the beads’ morphologies were observed using a scanning electron microscope (SEM). The FTIR results showed that the ultrasonication process caused the C-H bonds (1426 cm−1) to break down, resulting in polymer degradation. The SEM results showed that the ultrasonication caused the presence of cavities or pores in the cracked wall and a decrease in the beads’ size. In this study, the use of ultrasound during the encapsulation of citronella oil in Alg/Carr enhanced the encapsulation efficiency up to 95–97%. The kinetic evaluation of the oil release of the beads treated with ultrasound (UTS) showed a higher k1 value of the Ritger–Peppas model than that without ultrasonication (non-UTS), indicating that the oil release rate from the beads was faster. The R/F value from the Peppas–Sahlin model of the beads treated with UTS was smaller than that of the non-UTS model, revealing that the release of bioactive compounds from the UTS-treated beads was diffusion-controlled rather than due to a relaxation mechanism. This study suggests the potential utilization of UTS for controlling the bioactive compound release rate.

Sonochemistry: An emerging approach to fabricate biopolymer cross-linked emulsions for the delivery of bioactive compounds

Sonochemistry shows remarkable potential in the synthesis or modification of new micro/nanomaterials, particularly the cross-linked emulsions for drug delivery. However, the trend of utilizing sonochemical emulsions for delivery of food-derived bioactive compounds has been just started. The extension of sonochemistry as a tool for engineering bioactive delivery systems will make the approach more universal and greatly increase its applications in the food industry. This review summarizes different types of biopolymeric cross-linked emulsions (CLEs) synthesized via sonochemical approach, including CLEs, surface-modified CLEs, cross-linked high internal phase emulsions, and some novel systems templated on CLEs. Special emphasis is directed toward the cross-linking mechanisms of biopolymers at the oil-water interfaces under acoustic cavitation and the physicochemical principles underlying sonochemical fabrication. We also highlight the advantages and challenges associated with the delivery performance of each system for bioactive compounds. The potential in delivering bioactives using sonochemical emulsions has not been fully reached. There are still a number of issues that need to be overcome, including low cross-linking degree of biopolymers, degradation of bioactives in sonochemical process, and unclear biological fate of encapsulated bioactive compounds. This review may guide future trends in exploring efficient sonochemical strategies and multifunctional delivery systems for food applications.

Critical review on alterations in physiochemical properties and molecular structure of natural polysaccharides upon ultrasonication

Natural polymers, such as polysaccharides, cellulose, and starch, have been widely used in the chemical engineering, medicine, food, and cosmetics industries, which had a great many of biological activities. Natural polysaccharides origin from algae, fungi and plants were components of human diet since antique times. Ultrasonication achieved the breakage the polysaccharides reticulum in an ordered fashion. The factors of temperature, ratio of water/material, sonication frequency, time of exposure, pH of the sonication medium influenced the polysaccharide digestion. Sonication improved the enzyme catalysis over its substrate molecule. Positive health promoting slow digestive starch and resistant starch can be prepared quite easily by the sonication process. The aim of this review is to present the current status and scope of natural polymers as well as some emerging polymers with special characteristic. The physiochemical properties and molecular structure of natural carbohydrates under ultrasonic irradiation were also discussed. Moreover, Polysaccharide based films had industrial applications is formed by ultrasonication. Polysaccharide nanoparticles obtained by sonication had efficient water holding capacity. Sonication is an advanced method to improve the food quality. Hence, this review describes the effects of ultrasonication on physical, chemical, and molecular structure of natural polysaccharides.

Microencapsulated phase change material via Pickering emulsion stabilized by cellulose nanofibrils for thermal energy storage

A phase change material (PCM) has an ability to store and release a large amount of energy in a wide range of temperature by the latent heat of fusion upon melting and crystallization. Microencapsulation may protect PCM from undesirable reaction and leaching. Herein, we report the microencapsulation of n-hexadecane via oil-in-water Pickering emulsions stabilized by non-chemically modified cellulose nanofibrils (CNF). The maximum size of PCM-CNF microcapsules was 12 ± 3.4 μm in diameter. The surface coverage of the microcapsule by CNF was as high as 67%, consistent with porous morphology of the freeze-dried microcapsules. With 59% PCM loading, the PCM-CNF microcapsule exhibited 132.5 and 141.1 J/g as stored and released thermal energy, respectively. The microcapsule slurry showed a reversible change in storage modulus by one order of magnitude across the transition temperature of n-hexadecane. Combined results demonstrate the successful microencapsulation of PCM via CNF-based Pickering emulsions for a sustainable thermal energy storage material.

Fabrication and evaluation of nanocontainers for lipophilic anticancer drug delivery in 3D in vitro model

Presently, most of anticancer drugs are high toxic for normal cells and, and as a result, they have severe side effects. Moreover, most of the formulations are lipophilic and have poor selectivity. To overcome these limitations, various drug delivery systems could be proposed. The aim of the current study was to fabricate novel polysaccharide nanocontainers (NC) by one-step ultrasonication technique and to evaluate their accumulation efficacy and cytotoxicity in 2D (monolayer culture) and 3D (tumor spheroids) in vitro models. NC with mean sizes in a range of 340-420 nm with the core-shell structure are synthetized and characterized. The NC shell is composed from diethylaminoethyl dextran/xanthan gum polyelectrolyte complex, while the hydrophobic core was loaded with the lipophilic anticancer drug thymoquinone. To enhance NC accumulation in human breast adenocarcinoma MCF-7 cells, the NC surface was modified with poly-L-lysine (PLL) or polyethylene glycol. Cell uptake of the NC loaded with Nile Red into the tumor cells was investigated by laser scanning confocal microscopy, fluorescent flow cytometry and fluorimetry. Modification of the NC with PLL allowed to obtain the optimal drug delivery system with maximal cytotoxicity, which was tested by MTT-test. The developed NC are promising for lipophilic anticancer drug delivery.

Engineering and Application Perspectives on Designing an Antimicrobial Surface

Infections, contaminations, and biofouling resulting from micro- and/or macro-organisms remained a prominent threat to the public health, food industry, and aqua-/marine-related applications. Considering environmental and drug resistance concerns as well as insufficient efficacy on biofilms associated with conventional disinfecting reagents, developing an antimicrobial surface potentially improved antimicrobial performance by directly working on the microbes surrounding the surface area. Here we provide an engineering perspective on the logic of choosing materials and strategies for designing antimicrobial surfaces, as well as an application perspective on their potential impacts. In particular, we analyze and discuss requirements and expectations for specific applications and provide insights on potential misconnection between the antimicrobial solution and its targeted applications. Given the high translational barrier for antimicrobial surfaces, future research would benefit from a comprehensive understanding of working mechanisms for potential materials/strategies, and challenges/requirements for a targeted application.

Effect of pH on the Complex Coacervation and on the Formation of Layers of Sodium Alginate and PDADMAC

In this study, we investigated the thermodynamic features of a system based on oppositely charged polyelectrolytes, sodium alginate, and poly(diallyldimethylammonium chloride) (PDADMAC) at different pH values. Additionally, a comparison of the effects of the thermodynamic parameters on the growth of the layers based on the same polymers is presented. For this investigation, different techniques were combined to compare results from the association in solution and coassembled layers at the silicon surface. Dynamic light scattering (DLS) and isothermal titration calorimetry (ITC) were used for studies in solution, and the layer-by-layer technique was employed for the preparation of the polymer layers. Ellipsometry and atomic force microscopy (AFM) were used to characterize the layer thickness growth as a function of the solution pH, and interferometric confocal microscopy was employed to analyze the topography and roughness of the films. The titration of both polyelectrolytes in two different sequences of additions confirmed the mechanism; it involved a two-step process that was monitored by varying the enthalpy, as determined by ITC experiments, and the structural evolution of the aggregates into coacervates, according to DLS. The primary process is aggregation to form polyelectrolyte complexes having a smaller hydrodynamic diameter, which abruptly transit toward a secondary process because of the formation of coacervate particles that have a larger hydrodynamic diameter. Independent of pH and the sequence of addition, for the first process, both directions are entropically driven. However, the binding enthalpy (ΔH_b) decreased with a decrease in the pH of the solution. The layers grown for the PDADMAC/sodium alginate system demonstrated pH sensitivity with either linear or exponential behavior, depending on the pH values of the polyelectrolyte solutions. The more endothermic process at pH 10 afforded layers with a smaller thickness and with linear growth according to the increase in the number of layers from 5 to 20. Decreases in the pH of the solution resulted in the layers growing exponentially; additionally, a decrease in the ΔH_b of the association in the solution was observed. The layer thicknesses measured using ellipsometry and AFM data were in good agreement. Additionally, the influence of pH on the roughness and topography of the films was observed. Films from basic dipping solutions resulted in surfaces that were more homogeneous with less roughness; in contrast, films with more layers and those formed in a low-pH dipping solution were rougher and less homogeneous.

A Robust Aqueous Core-Shell-Shell Coconut-like Nanostructure for Stimuli-Responsive Delivery of Hydrophilic Cargo

Conventional delivery systems for hydrophilic material still face critical challenges toward practical applications, including poor retention abilities, lack of stimulus responsiveness, and low bioavailability. Here, we propose a robust encapsulation strategy for hydrophilic cargo to produce a wide class of aqueous core-shell-shell coconut-like nanostructures featuring excellent stability and multifunctionality. The numerous active groups (-SH, -NH₂, and -COOH) of the protein-polysaccharide wall material enable the formation of shell-cross-linked nanocapsules enclosing a liquid water droplet during acoustic cavitation. A subsequent pH switch can trigger the generation of an additional shell through the direct deposition of non-cross-linked protein back onto the cross-linked surface. Using anthocyanin as a model hydrophilic bioactive, these nanocapsules show high encapsulation efficiency, loading content, tolerance to environmental stresses, biocompatibility, and high cellular uptake. Moreover, the composite double shells driven by both covalent bonding and electrostatics provide the nanocapsules with pH/redox dual stimuli-responsive behavior. Our approach is also feasible for any shell material that can be cross-linked via ultrasonication, offering the potential to encapsulate diverse hydrophilic functional components, including bioactive molecules, nanocomplexes, and water-dispersible inorganic nanomaterials. Further development of this strategy should hold promise for designing versatile nanoengineered core-shell-shell nanoplatforms for various applications, such as the oral absorption of hydrophilic drugs/nutraceuticals and the smart delivery of therapeutics.

A simple route to renewable high internal phase emulsions (HIPEs) strengthened by successive cross-linking and electrostatics of polysaccharides

A novel renewable and processable HIPE was synthesized by a simple strategy without using any surfactants or synthetic particles.

Modified Mesoporous Silica Nanoparticles with a Dual Synergetic Antibacterial Effect

Application of mesoporous silica nanoparticles (MSNs) as antifouling/antibacterial carriers is limited and specifically with a dual synergetic effect. In the present work, MSNs modified with quaternary ammonium salts (QASs) and loaded with the biocide Parmetol S15 were synthesized as functional fillers for antifouling/antibacterial coatings. From the family of the MSNs, MCM-48 was selected as a carrier because of its cubic pore structure, high surface area, and high specific pore volume. The QASs used for the surface modification of MCM-48 were dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride and dimethyltetradecyl[3-(triethoxysilyl)propyl]ammonium chloride. The QAS-modified MCM-48 reveals strong covalent bonds between the QAS and the surface of the nanoparticles. The surface functionalization was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, and ζ-potential measurements. Additional loading of the QAS-modified MCM-48 with a commercially available biocide (Parmetol S15) resulted in a synergetic dual antibacterial/antifouling effect. Either loaded or unloaded QAS-modified MSNs exhibited high antibacterial performance confirming their dual activity. The QAS-modified MCM-48 loaded with the biocide Parmetol S15 killed all exposed bacteria after 3 h of incubation and presented 100% reduction at the antibacterial tests against Gram-negative and Gram-positive bacteria. Furthermore, the QAS-modified MCM-48 without Parmetol S15 presented 77-89% reduction against the exposed Gram-negative bacteria and 78-94% reduction against the exposed Gram-positive bacteria. In addition, the modified MCM-48 was mixed with coating formulations, and its antifouling performance was assessed in a field test trial in northern Red Sea. All synthesized paints presented significant antifouling properties after 5 months of exposure in real seawater conditions, and the dual antifouling effect of the nanoparticles was confirmed.

Encapsulation of Antifouling Organic Biocides in Poly(lactic acid) Nanoparticles

The scope of the current research was to assess the feasibility of encapsulating three commercial antifouling compounds, Irgarol 1051, Econea and Zinc pyrithione, in biodegradable poly(lactic acid) (PLA) nanoparticles. The emulsification–solvent evaporation technique was herein utilized to manufacture nanoparticles with a biocide:polymer ratio of 40%. The loaded nanoparticles were analyzed for their size and size distribution, zeta potential, encapsulation efficiency and thermal properties, while the relevant physicochemical characteristics were correlated to biocide–polymer system. In addition, the encapsulation process was scaled up and the prepared nanoparticles were dispersed in a water-based antifouling paint in order to examine the viability of incorporating nanoparticles in such coatings. Metallic specimens were coated with the nanoparticles-containing paint and examined regarding surface morphology.

Flexible Antibacterial Film Based on Conjugated Polyelectrolyte/Silver Nanocomposites

In this work, we report a flexible film based on conjugated polyelectrolyte/silver nanocomposites with efficient antibacterial activity. A flexible poly(dimethylsiloxane) film served as a substrate for deposition of nanostructured silver. A light-activated antibacterial agent, based on the cationic conjugated polyelectrolyte poly({9,9-bis[6'-(N,N-trimethylamino)hexyl]-2,7-fluorenyleneethynylene}-alt-co-1,4-(2,5-dimethoxy)phenylene)dibromide (PFEMO) was self-assembled on the negatively charged substrate. By changing the thickness of the poly(l-lysine)/poly(acrylic acid) multilayers between the metal substrate and PFEMO, we obtained concomitant enhancement of PFEMO fluorescence, phosphorescence, and reactive oxygen species generation. These enhancements were induced by surface plasmon resonance effects of the Ag nanoparticles, which overlapped the PFEMO absorption band. Owing to the combination of enhanced bactericidal effects and good flexibility, these films have great potential for use as novel biomaterials for preventing bacterial infections.

Formulation for Oral Delivery of Lactoferrin Based on Bovine Serum Albumin and Tannic Acid Multilayer Microcapsules

Lactoferrin (Lf) has considerable potential as a functional ingredient in food, cosmetic and pharmaceutical applications. However, the bioavailability of Lf is limited as it is susceptible to digestive enzymes in gastrointestinal tract. The shells comprising alternate layers of bovine serum albumin (BSA) and tannic acid (TA) were tested as Lf encapsulation system for oral administration. Lf absorption by freshly prepared porous 3 μm CaCO₃ particles followed by Layer-by-Layer assembly of the BSA-TA shells and dissolution of the CaCO₃ cores was suggested as the most efficient and harmless Lf loading method. The microcapsules showed high stability in gastric conditions and effectively protected encapsulated proteins from digestion. Protective efficiency was found to be 76 ± 6% and 85 ± 2%, for (BSA-TA)₄ and (BSA-TA)₈ shells, respectively. The transit of Lf along the gastrointestinal tract (GIT) of mice was followed in vivo and ex vivo using NIR luminescence. We have demonstrated that microcapsules released Lf in small intestine allowing 6.5 times higher concentration than in control group dosed with the same amount of free Lf. Significant amounts of Lf released from microcapsules were then absorbed into bloodstream and accumulated in liver. Suggested encapsulation system has a great potential for functional foods providing lactoferrin.

Toward an Understanding of the Microstructure and Interfacial Properties of PIMs/ZIF-8 Mixed Matrix Membranes

A study integrating advanced experimental and modeling tools was undertaken to characterize the microstructural and interfacial properties of mixed matrix membranes (MMMs) composed of the zeolitic imidazolate framework ZIF-8 nanoparticles (NPs) and two polymers of intrinsic microporosity (PIM-1 and PIM-EA-TB). Analysis probed both the initial ZIF-8/PIM-1 colloidal suspensions and the final hybrid membranes. By combination of dynamic light scattering (DLS) and transmission electron microscopy (TEM) analytical and imaging techniques with small-angle X-ray scattering (SAXS), the colloidal suspensions were shown to consist mainly of two distinct kinds of particles, namely, polymer aggregates of about 200 nm in diameter and densely packed ZIF-8-NP aggregates of a few 100 nm in diameter with a 3 nm thick polymer top-layer. Such aggregates are likely to impart the granular texture of ZIF-8/PIMs MMMs as shown by SEM-XEDS analysis. At the molecular scale, modeling studies showed that the surface coverage of ZIF-8 NPs by both polymers appears not to be optimal with the presence of microvoids at the interfaces that indicates only a moderate compatibility between the polymer and ZIF-8. This study shows that the microstructure of MMMs results from a complex interplay between the ZIF-8/PIM compatibility, solvent, surface chemistry of the ZIF-8 NPs, and the physicochemical properties of the polymers such as molecular structure and rigidity.

Ultrasonically treated liquid interfaces for progress in cleaning and separation processes

Cleaning and separation processes of liquids can be advanced by acoustic cavitation through bubbles with unique physico-chemical properties.

Ultrasonically Assisted Polysaccharide Microcontainers for Delivery of Lipophilic Antitumor Drugs: Preparation and in Vitro Evaluation

High toxicity, poor selectivity, and severe side effects are major drawbacks of anticancer drugs. Various drug delivery systems could be proposed to overcome these limitations. The aim of this study was to fabricate polysaccharide microcontainers (MCs) loaded with thymoquinone (TQ) by a one-step ultrasonication technique and to study their cellular uptake and cytotoxicity in vitro. Two MC fractions with a mean size of 500 nm (MC-0.5) and 2 μM (MC-2) were prepared and characterized. Uptake of the MCs by mouse melanoma M-3 cells was evaluated in both 2D (monolayer culture) and 3D (multicellular tumor spheroids) models by confocal microscopy, flow cytometry, and fluorimetry. The higher cytotoxicity of the TQ-MC-0.5 sample than the TQ-MC-2 fraction was in good correlation with higher MC-0.5 accumulation in the cells. The MC-0.5 beads were more promising than the MC-2 particles because of a higher cellular uptake in both 2D and 3D models, an enhanced antitumor effect, and a lower nonspecific toxicity.