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Polymeric Systems Loaded with Natural Bioactive Compounds
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Polymeric Systems Loaded with Natural Bioactive Compounds

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: 31 December 2024 | Viewed by 32102

Special Issue Editors

Prof. Dr. Marcel Popa

E-Mail Website
Guest Editor
“Cristofor Simionescu” Faculty of Chemical Engineering and Environment Protection, “Gheorghe Asachi” Technical University, Iasi, Romania
Interests: polysaccharide modification; bioactive polymers; biomaterials; hydrogels; interpenetrated networks; micro- and nanoparticles (spheres and capsules); hybrid and functionalized nanoparticles for drug targeting; drug delivery; polymer–drug conjugates
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Leonard-Ionut Atanase

E-Mail Website
Guest Editor
1. Department of Biomaterials, Faculty of Medical Dentistry, “Apollonia” University of Iasi, 700511 Iasi, Romania
2. Academy of Romanian Scientists, 050045 Bucharest, Romania
Interests: block and graft copolymers; micelles; colloids; emulsions; drug delivery; polysaccharides
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

From ancient times people have used natural products derived from plants and sometimes animals as medicines against various diseases because they show great structural diversity that influences biological properties and bioavailability. Natural products such as polyphenols, omega-3 fatty acids, phytosterols, carotenoids, vitamins, alkaloids etc. can modulate metabolic processes and demonstrate positive properties such as antioxidant effect, inhibition of receptor activities, inhibition or induction of enzymes, and the induction and inhibition of gene expression. However, most bioactive natural compounds have low water solubility, stability and bioavailability. Nanotechnology plays an important role in improving these properties, improving their absorption, protecting them from premature degradation in the body and prolonging their circulation time. Many nanostructured systems have been developed for the loading, transport and controlled release of the active compound into the body, or even at the specific target of these natural products. These include hydrogels/nanohydrogels, liposomes, polymeric nanoparticles (nanospheres and nanocapsules), solid lipid nanoparticles, nanoemulsions, polymeric micelles etc.

This Special Issue aims to present the latest aspects regarding the preparation and characterization of natural biologically active principles loaded in polymer-based films, hydrogels, micro/nanoparticles, micelles, capsules, implants, inserts, liposomes stabilized by polymer coatings etc.

Prof. Dr. Marcel Popa
Prof. Dr. Leonard Atanase
Guest Editors

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Keywords

  • polymer–natural drug systems
  • polyphenols
  • polymer–drug conjugates
  • biomaterials
  • drug delivery
  • natural bioactive compounds
  • active targeting
  • omega 3 fatty acids
  • carotenoids
  • vitamins

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Published Papers (9 papers)

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29 pages, 4913 KiB  
Article
An Accessible Method to Improve the Stability and Reusability of Porcine Pancreatic α-Amylase via Immobilization in Gellan-Based Hydrogel Particles Obtained by Ionic Cross-Linking with Mg2+ Ions
by Camelia Elena Tincu (Iurciuc), Brahim Bouhadiba, Leonard Ionut Atanase, Corneliu Sergiu Stan, Marcel Popa and Lăcrămioara Ochiuz
Molecules 2023, 28(12), 4695; https://doi.org/10.3390/molecules28124695 - 11 Jun 2023
Cited by 6 | Viewed by 2132
Abstract
Amylase is an enzyme used to hydrolyze starch in order to obtain different products that are mainly used in the food industry. The results reported in this article refer to the immobilization of α-amylase in gellan hydrogel particles ionically cross-linked with Mg2+ [...] Read more.
Amylase is an enzyme used to hydrolyze starch in order to obtain different products that are mainly used in the food industry. The results reported in this article refer to the immobilization of α-amylase in gellan hydrogel particles ionically cross-linked with Mg2+ ions. The obtained hydrogel particles were characterized physicochemically and morphologically. Their enzymatic activity was tested using starch as a substrate in several hydrolytic cycles. The results showed that the properties of the particles are influenced by the degree of cross-linking and the amount of immobilized α-amylase enzyme. The temperature and pH at which the immobilized enzyme activity is maximum were T = 60 °C and pH = 5.6. The enzymatic activity and affinity of the enzyme to the substrate depend on the particle type, and this decreases for particles with a higher cross-linking degree owing to the slow diffusion of the enzyme molecules inside the polymer’s network. By immobilization, α-amylase is protected from environmental factors, and the obtained particles can be quickly recovered from the hydrolysis medium, thus being able to be reused in repeated hydrolytic cycles (at least 11 cycles) without a substantial decrease in enzymatic activity. Moreover, α-amylase immobilized in gellan particles can be reactivated via treatment with a more acidic medium. Full article
(This article belongs to the Special Issue Polymeric Systems Loaded with Natural Bioactive Compounds)
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Figure 1

Figure 1
<p>Schematic structure of α-amylase immobilized in ionically cross-linked gellan particles.</p> Full article ">Figure 2
<p>FT-IR spectra of gellan, α-amylase, and sample A4.</p> Full article ">Figure 3
<p>Scanning electron microscopy photographs of particles containing immobilized α-amylase cross-linked with (<b>a</b>) 1% and (<b>b</b>) 2% magnesium acetate in the cross-linking bath.</p> Full article ">Figure 4
<p>Variation of degree of swelling over time for three types of particles with immobilized α-amylase, obtained using different concentrations of magnesium acetate in the cross-linking bath (Q1%-A3, Q2%-A4, and Q3%-A5 magnesium acetate).</p> Full article ">Figure 5
<p>Michaelis–Menten kinetics (<b>a</b>) and Lineweaver–Burk plot (<b>b</b>) for free enzyme and enzyme immobilized in magnesium acetate cross-linked gellan particles A3 and A4.</p> Full article ">Figure 6
<p>Influence of pH (<b>a</b>) and temperature (<b>b</b>) on enzyme activity for free and immobilized enzyme.</p> Full article ">Figure 7
<p>The α-amylase inhibition percentage on NaCl for free and immobilized α-amylase (<b>a</b>) and enzyme activity in the presence of different salt concentrations (<b>b</b>).</p> Full article ">Figure 8
<p>Relative activity determinations in repeated hydrolytic cycles for particles with immobilized α-amylase (3 mg/mL), using starch as substrate at (<b>a</b>) pH 5.6 and (<b>b</b>) pH 5.2 and pH = 5.6. The temperature at which the catalytic activity of the particles was tested was 35 °C. The duration between hydrolytic cycles was 10 min.</p> Full article ">Figure 9
<p>Schematic presentation of the preparation of gellan particles with 3 mg of immobilized α-amylase.</p> Full article ">
17 pages, 4890 KiB  
Article
Silymarin Encapsulated Liposomal Formulation: An Effective Treatment Modality against Copper Toxicity Associated Liver Dysfunction and Neurobehavioral Abnormalities in Wistar Rats
by Tuba Maryam, Nosheen Fatima Rana, Sultan M. Alshahrani, Farhat Batool, Misha Fatima, Tahreem Tanweer, Salma Saleh Alrdahe, Yasmene F. Alanazi, Ifat Alsharif, Fatima S. Alaryani, Amer Sohail Kashif and Farid Menaa
Molecules 2023, 28(3), 1514; https://doi.org/10.3390/molecules28031514 - 3 Feb 2023
Cited by 9 | Viewed by 2769
Abstract
Wilson’s disease causes copper accumulation in the liver and extrahepatic organs. The available therapies aim to lower copper levels by various means. However, a potent drug that can repair the damaged liver and brain tissue is needed. Silymarin has hepatoprotective, antioxidant, and cytoprotective [...] Read more.
Wilson’s disease causes copper accumulation in the liver and extrahepatic organs. The available therapies aim to lower copper levels by various means. However, a potent drug that can repair the damaged liver and brain tissue is needed. Silymarin has hepatoprotective, antioxidant, and cytoprotective properties. However, poor oral bioavailability reduces its efficacy. In this study, a “thin film hydration method” was used for synthesizing silymarin-encapsulated liposome nanoparticles (SLNPs) and evaluated them against copper toxicity, associated liver dysfunction and neurobehavioral abnormalities in Wistar rats. After copper toxicity induction, serological and behavioral assays were conducted to evaluate treatment approaches. Histological examination of the diseased rats revealed severe hepatocyte necrosis and neuronal vacuolation. These cellular degenerations were mild in rats treated with SLNPs and a combination of zinc and SLNPs (ZSLNPs). SLNPs also decreased liver enzymes and enhanced rats’ spatial memory significantly (p = 0.006) in the diseased rats. During forced swim tests, SLNPs treated rats exhibited a 60-s reduction in the immobility period, indicating reduced depression. ZSLNPs were significantly more effective than traditional zinc therapy in decreasing the immobility period (p = 0.0008) and reducing liver enzymes, but not in improving spatial memory. Overall, SLNPs enhanced oral silymarin administration and managed copper toxicity symptoms. Full article
(This article belongs to the Special Issue Polymeric Systems Loaded with Natural Bioactive Compounds)
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Figure 1

Figure 1
<p>Comparative UV–VIS spectra of blank and silymarin LNPs and their components DPPC, cholesterol, silymarin, and PEG 2000, using a UV–Vis 2800 (BMS Biotechnology Medical Services, Madrid, Spain).</p> Full article ">Figure 2
<p>Comparative FTIR spectra of DPPC, cholesterol, PEG−2000, silymarin, silymarin LNPs, and blank LNPs, using a Bruker FTIR spectrophotometer ALPHA II (Westborough, MA, USA).</p> Full article ">Figure 3
<p>Scanning electron microscopy image of silymarin LNPs, depicting their size and morphology, using the VEGA3 LMU scanning electron microscope (Tescan, Brno, Czech Republic).</p> Full article ">Figure 4
<p>Zeta Potential of (<b>a</b>) blank LNPs and (<b>b</b>) silymarin LNPs, using Malvern Zetasizer, version 7.12 (Malvern, Worcestershire, UK).</p> Full article ">Figure 5
<p>(<b>a</b>) Cumulative drug release of silymarin LNPs over 15 h and (<b>b</b>) curve fitting using KinetDS software to determine release model using the subplots.</p> Full article ">Figure 6
<p>Mean immobility time of rats (<span class="html-italic">n</span> = 5), and statistical significance between groups using independent <span class="html-italic">t</span>-test, as observed in forced swim test, carried out after the following treatments for a period of 21 days through gavage: diseased, SLNPs (500 µg/kg BW), silymarin (10 mg/kg BW), Zn (10 mg/kg BW), ZSLNPs (10 mg/kg BW + 500 µg/kg BW), and BLNPs (500 µg/kg BW).</p> Full article ">Figure 7
<p>Mean Percentage Spatial Memory of Rats (<span class="html-italic">n</span> = 5), as observed in Y maze test and calculated using equation ii, and statistical significance between groups independent <span class="html-italic">t</span>-test, carried out after the following treatments for a period of 21 days: diseased, SLNPs (500 µg/kg BW), silymarin (10 mg/kg BW), Zn (10 mg/kg BW), ZSLNPs (10 mg/kg BW + 500 µg/kg BW), and BLNPs (500 µg/kg BW).</p> Full article ">Figure 8
<p>(<b>a</b>) Mean body and (<b>b</b>) liver weights of rats (<span class="html-italic">n</span> = 5), with the body weight recorded weekly and liver weights measured after sacrifice using a weight scale, and statistical significance between groups using independent <span class="html-italic">t</span>-test, following the different treatments for a period of 21 days through gavage: diseased, SLNPs (500 µg/kg BW), silymarin (10 mg/kg BW), Zn (10 mg/kg BW), ZSLNPs (10 mg/kg BW + 500 µg/kg BW), and BLNPs (500 µg/kg BW).</p> Full article ">Figure 9
<p>Mean liver function test results of rats (<span class="html-italic">n</span> = 5) (<b>a</b>) bilirubin and (<b>b</b>) AST, and statistical significance between groups using independent <span class="html-italic">t</span>-test, after sacrifice following the different treatments for a period of 21 days through gavage: diseased, SLNPs (500 µg/kg BW), silymarin (10 mg/kg BW), Zn (10 mg/kg BW), ZSLNPs (10 mg/kg BW + 500 µg/kg BW), and BLNPs (500 µg/kg BW).</p> Full article ">Figure 10
<p>Mean liver function test results of rats (<span class="html-italic">n</span> = 5) (<b>a</b>) ALP and (<b>b</b>) ALT, and statistical significance between groups using independent <span class="html-italic">t</span>-test, after sacrifice following the different treatments for a period of 21 days through gavage: diseased, SLNPs (500 µg/kg BW), silymarin (10 mg/kg BW), Zn (10 mg/kg BW), ZSLNPs (10 mg/kg BW + 500 µg/kg BW), and BLNPs (500 µg/kg BW).</p> Full article ">Figure 11
<p>Liver histopathology of rats after sacrifice following the treatments for a period of 21 days (<b>a</b>) normal (<b>b</b>) diseased (<b>c</b>) BLNPs Treated (500 µg/kg BW) (<b>d</b>) silymarin treated (10 mg/kg BW) (<b>e</b>) SLNPs Treated (500 µg/kg BW) (<b>f</b>) Zn Treated (10 mg/kg BW) (<b>g</b>) ZSLNPs Treated (10 mg/kg BW + 500 µg/kg BW).</p> Full article ">Figure 12
<p>Brain histopathology of rats after sacrifice following the treatments for a period of 21 days (<b>a</b>) normal (<b>b</b>) diseased (<b>c</b>) BLNPs Treated (500 µg/kg BW) (<b>d</b>) silymarin Treated (10 mg/kg BW) (<b>e</b>) SLNPs Treated (500 µg/kg BW) (<b>f</b>) Zn Treated (10 mg/kg BW) (<b>g</b>) ZSLNPs Treated (10 mg/kg BW + 500 µg/kg BW).</p> Full article ">Figure 13
<p>Flow chart showing study design from acclimatization, induction, treatment till analysis.</p> Full article ">
21 pages, 4422 KiB  
Article
Development of Gastroretentive Carriers for Curcumin-Loaded Solid Dispersion Based on Expandable Starch/Chitosan Films
by Worrawee Siripruekpong, Ousanee Issarachot, Kanidta Kaewkroek and Ruedeekorn Wiwattanapatapee
Molecules 2023, 28(1), 361; https://doi.org/10.3390/molecules28010361 - 1 Jan 2023
Cited by 2 | Viewed by 2755
Abstract
Curcumin, a polyphenolic extract from the rhizomes of turmeric, exhibits antioxidant, anti-inflammatory, and anticancer activities, which are beneficial for the treatment of gastric diseases. However, curcumin’s therapeutic usefulness is restricted by its low aqueous solubility and short gastric residence time. In this study, [...] Read more.
Curcumin, a polyphenolic extract from the rhizomes of turmeric, exhibits antioxidant, anti-inflammatory, and anticancer activities, which are beneficial for the treatment of gastric diseases. However, curcumin’s therapeutic usefulness is restricted by its low aqueous solubility and short gastric residence time. In this study, curcumin-loaded solid dispersion (ratio 1:5) was prepared using Eudragit® EPO (Cur EPO-SD), resulting in an approximately 12,000-fold increase in solubility to 6.38 mg/mL. Expandable films incorporating Cur EPO-SD were subsequently prepared by solvent casting using different types of starch (banana, corn, pregelatinized, and mung bean starch) in combination with chitosan. Films produced from banana, corn, pregelatinized and mung bean starch unfolded and expanded upon exposure to simulated gastric medium, resulting in sustained release of 80% of the curcumin content within 8 h, whereas films based on pregelatinized starch showed immediate release characteristics. Curcumin-loaded expandable films based on different types of starch exhibited similar cytotoxic effects toward AGS cells and more activity than unformulated curcumin. Furthermore, the films resulted in increased anti-inflammatory activity against RAW 264.7 macrophage cells compared with the NSAID, indomethacin. These findings demonstrate the potential of expandable curcumin-loaded films as gastroretentive dosage forms for the treatment of gastric diseases and to improve oral bioavailability. Full article
(This article belongs to the Special Issue Polymeric Systems Loaded with Natural Bioactive Compounds)
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Figure 1

Figure 1
<p>In vitro dissolution studies of curcumin, curcumin–Eudragit EPO solid dispersions and curcumin–Eudragit EPO physical mixtures at various ratios. Note: * denotes <span class="html-italic">p</span>-value &lt; 0.01.</p> Full article ">Figure 2
<p>Fourier transform infrared spectra of (<b>a</b>) curcumin extract, (<b>b</b>) Eudragit EPO, and curcumin solid dispersion (CUR-SD) at <span class="html-italic">w/w</span> ratios of (<b>c</b>) 1:3, (<b>d</b>) 1:5, (<b>e</b>) 1:6, and (<b>f</b>) 1:8.</p> Full article ">Figure 2 Cont.
<p>Fourier transform infrared spectra of (<b>a</b>) curcumin extract, (<b>b</b>) Eudragit EPO, and curcumin solid dispersion (CUR-SD) at <span class="html-italic">w/w</span> ratios of (<b>c</b>) 1:3, (<b>d</b>) 1:5, (<b>e</b>) 1:6, and (<b>f</b>) 1:8.</p> Full article ">Figure 3
<p>Fourier transform infrared spectra of (<b>a</b>) curcumin extract, (<b>b</b>) Eudragit EPO, and curcumin physical mixture (CUR-PM) at <span class="html-italic">w/w</span> ratios of (<b>c</b>) 1:3, (<b>d</b>) 1:5, (<b>e</b>) 1:6, and (<b>f</b>) 1:8.</p> Full article ">Figure 3 Cont.
<p>Fourier transform infrared spectra of (<b>a</b>) curcumin extract, (<b>b</b>) Eudragit EPO, and curcumin physical mixture (CUR-PM) at <span class="html-italic">w/w</span> ratios of (<b>c</b>) 1:3, (<b>d</b>) 1:5, (<b>e</b>) 1:6, and (<b>f</b>) 1:8.</p> Full article ">Figure 4
<p>Powder X-ray diffractograms of curcumin physical mixture (CUR-PM) (<b>a</b>–<b>d</b>) in <span class="html-italic">w/w</span> ratios of (<b>a</b>) 1:8, (<b>b</b>) 1:6, (<b>c</b>) 1:5, and (<b>d</b>) 1:3; (<b>e</b>) curcumin extract; curcumin solid dispersion (CUR-SD) (<b>f</b>–<b>i</b>) in <span class="html-italic">w/w</span> ratios of (<b>f</b>) 1:8, (<b>g</b>) 1:6, (<b>h</b>) 1:5, and (<b>i</b>) 1:3; and (<b>j</b>) Eudragit EPO.</p> Full article ">Figure 5
<p>Swelling behavior of curcumin-loaded expandable films: (<b>A</b>) banana starch, (<b>B</b>) corn starch, (<b>C</b>) mung bean starch, and (<b>D</b>) pregelatinized starch.</p> Full article ">Figure 6
<p>Scanning electron micrographs of curcumin-loaded expandable films: (<b>A</b>,<b>B</b>) banana starch (CBS2M.3), (<b>C</b>,<b>D</b>) corn starch (CCS2M.3), (<b>E</b>,<b>F</b>) mung bean starch (CMS2M.3), and (<b>G</b>,<b>H</b>) pregelatinized starch (CPS2M.3).</p> Full article ">Figure 7
<p>Unfolding and expansion behavior of curcumin-loaded films in simulated gastric fluid.</p> Full article ">Figure 8
<p>In vitro release of curcumin from expandable starch/chitosan films: (<b>A</b>) banana starch, (<b>B</b>) corn starch, (<b>C</b>) mung bean starch, and (<b>D</b>) pregelatinized starch.</p> Full article ">
15 pages, 2384 KiB  
Article
Effect of Loblolly Pine (Pinus taeda L.) Hemicellulose Structure on the Properties of Hemicellulose-Polyvinyl Alcohol Composite Film
by Huaizhi Pan, Biao Zheng, Hui Yang, Yingying Guan, Liuyang Zhang, Xiaoli Xu, Aimin Wu and Huiling Li
Molecules 2023, 28(1), 46; https://doi.org/10.3390/molecules28010046 - 21 Dec 2022
Cited by 3 | Viewed by 1855
Abstract
Hemicellulose is the second most abundant natural polysaccharide and a promising feedstock for biomaterial synthesis. In the present study, the hemicellulose of loblolly pine was obtained by the alkali extraction-graded ethanol precipitation technique, and the hemicellulose-polyvinyl alcohol (hemicellulose-PVA) composite film was prepared by [...] Read more.
Hemicellulose is the second most abundant natural polysaccharide and a promising feedstock for biomaterial synthesis. In the present study, the hemicellulose of loblolly pine was obtained by the alkali extraction-graded ethanol precipitation technique, and the hemicellulose-polyvinyl alcohol (hemicellulose-PVA) composite film was prepared by film casting from water. Results showed that hemicellulose with a low degree of substitution is prone to self-aggregation during film formation, while hemicellulose with high branching has better compatibility with PVA and is easier to form a homogeneous composite film. In addition, the higher molecular weight of hemicellulose facilitates the preparation of hemicellulose-PVA composite film with better mechanical properties. More residual lignin in hemicellulose results in the better UV shielding ability of the composite film. This study provides essential support for the efficient and rational utilization of hemicellulose. Full article
(This article belongs to the Special Issue Polymeric Systems Loaded with Natural Bioactive Compounds)
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Figure 1

Figure 1
<p>FT-IR spectra of graded ethanol precipitated hemicellulose.</p> Full article ">Figure 2
<p>HSQC NMR spectrum of H45.</p> Full article ">Figure 3
<p>Thermogravimetric analysis of graded ethanol precipitated hemicellulose; (<b>A</b>): TG curve; (<b>B</b>): DTG curve.</p> Full article ">Figure 4
<p>Laminated film picture, (<b>A</b>): composite film photo; (<b>B</b>): SEM image.</p> Full article ">Figure 5
<p>Stress-strain curve of hemicellulose-PVA composite film.</p> Full article ">Figure 6
<p>UV-Vis transmission curve of hemicellulose-PVA composite film.</p> Full article ">Figure 7
<p>Thermogravimetric analysis of hemicellulose-PVA composite film; (<b>A</b>): TG curve; (<b>B</b>): DTG curve.</p> Full article ">Figure 8
<p>Scheme for the fractionation of alkali soluble hemicelluloses from loblolly pine by the graded ethanol precipitation.</p> Full article ">
22 pages, 4858 KiB  
Article
pH-Responsive Hydrogel Beads Based on Alginate, κ-Carrageenan and Poloxamer for Enhanced Curcumin, Natural Bioactive Compound, Encapsulation and Controlled Release Efficiency
by Katarina S. Postolović, Milan D. Antonijević, Biljana Ljujić, Marina Miletić Kovačević, Marina Gazdić Janković and Zorka D. Stanić
Molecules 2022, 27(13), 4045; https://doi.org/10.3390/molecules27134045 - 23 Jun 2022
Cited by 22 | Viewed by 3324
Abstract
Polyphenolic compounds are used for treating various diseases due to their antioxidant and anticancer properties. However, utilization of hydrophobic compounds is limited due to their low bioavailability. In order to achieve a greater application of hydrophobic bioactive compounds, hydrogel beads based on biopolymers [...] Read more.
Polyphenolic compounds are used for treating various diseases due to their antioxidant and anticancer properties. However, utilization of hydrophobic compounds is limited due to their low bioavailability. In order to achieve a greater application of hydrophobic bioactive compounds, hydrogel beads based on biopolymers can be used as carriers for their enhanced incorporation and controlled delivery. In this study, beads based on the biopolymers-κ-carrageenan, sodium alginate and poloxamer 407 were prepared for encapsulation of curcumin. The prepared beads were characterized using IR, SEM, TGA and DSC. The curcumin encapsulation efficiency in the developed beads was 95.74 ± 2.24%. The release kinetics of the curcumin was monitored in systems that simulate the oral delivery (pH 1.2 and 7.4) of curcumin. The drug release profiles of the prepared beads with curcumin indicated that the curcumin release was significantly increased compared with the dissolution of curcumin itself. The cumulative release of curcumin from the beads was achieved within 24 h, with a final release rate of 12.07% (gastric fluid) as well as 81.93% (intestinal fluid). Both the in vitro and in vivo studies showed that new hydrogel beads based on carbohydrates and poloxamer improved curcumin’s bioavailability, and they can be used as powerful carriers for the oral delivery of different hydrophobic nutraceuticals. Full article
(This article belongs to the Special Issue Polymeric Systems Loaded with Natural Bioactive Compounds)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>(<b>a</b>) Car/Alg beads, (<b>b</b>) Car/Alg-Cur beads, (<b>c</b>) Car/Alg/Pol beads and (<b>d</b>) Car/Alg/Pol-Cur beads.</p> Full article ">Figure 2
<p>Swelling degree of beads with different carrageenan/alginate ratios in (<b>a</b>) HCl solution (pH 1.2) and (<b>b</b>) PBS solution (pH 7.4).</p> Full article ">Figure 3
<p>Swelling degree of beads with different poloxamer concentrations in (<b>a</b>) HCl solution (pH 1.2) and (<b>b</b>) PBS solution (pH 7.4).</p> Full article ">Figure 4
<p>Curcumin encapsulation efficiency.</p> Full article ">Figure 5
<p>FTIR spectra of (<b>a</b>) alginate, κ-carrageenan, poloxamer and curcumin as well as (<b>b</b>) Car/Alg, Car/Alg/Pol, Car/Alg-Cur and Car/Alg/Pol-Cur beads.</p> Full article ">Figure 6
<p>SEM images at 200, 500 and 2000 magnifications of Car/Alg (<b>a</b>–<b>a″</b>), Car/Alg-Cur (<b>b</b>–<b>b″</b>), Car/Alg/Pol (<b>c</b>–<b>c″</b>) and Car/Alg/Pol-Cur beads (<b>d</b>–<b>d″</b>).</p> Full article ">Figure 7
<p>(<b>a</b>) TGA thermograms of pure κ-carrageenan, alginate, curcumin, Car/Alg and Car/Alg/-Cur. (<b>b</b>) TGA thermograms of pure poloxamer, curcumin, Car/Alg, Car/Alg/Pol and Car/Alg/Pol-Cur beads.</p> Full article ">Figure 8
<p>DSC thermograms of pure curcumin, poloxamer, Car/Alg and Car/Alg/Pol-Cur beads.</p> Full article ">Figure 9
<p>Release profile of curcumin from Car/Alg/Pol-Cur beads in simulated gastrointestinal conditions.</p> Full article ">Figure 10
<p>NO produced from activated RAW 264.7 cells after treatment with LPS (control), Car/Alg/Pol and Car/Alg/Pol-Cur hydrogel beads (10–100 μg/mL).</p> Full article ">Figure 11
<p>Curcumin plasma concentration in the mice after oral administration of curcumin aqueous suspension and Car/Alg/Pol-Cur beads at a curcumin dose of 50 mg/kg (<span class="html-italic">n</span> = 3).</p> Full article ">
12 pages, 2619 KiB  
Article
Evaluation of Electrospun PCL-PLGA for Sustained Delivery of Kartogenin
by Steven Elder, John Graham Roberson, James Warren, Robert Lawson, Daniel Young, Sean Stokes and Matthew K. Ross
Molecules 2022, 27(12), 3739; https://doi.org/10.3390/molecules27123739 - 10 Jun 2022
Cited by 6 | Viewed by 2616
Abstract
In this study, kartogenin was incorporated into an electrospun blend of polycaprolactone and poly(lactic-co-glycolic acid) (1:1) to determine the feasibility of this system for sustained drug delivery. Kartogenin is a small-molecule drug that could enhance the outcome of microfracture, a cartilage restoration procedure, [...] Read more.
In this study, kartogenin was incorporated into an electrospun blend of polycaprolactone and poly(lactic-co-glycolic acid) (1:1) to determine the feasibility of this system for sustained drug delivery. Kartogenin is a small-molecule drug that could enhance the outcome of microfracture, a cartilage restoration procedure, by selectively stimulating chondrogenic differentiation of endogenous bone marrow mesenchymal stem cells. Experimental results showed that kartogenin did not affect the electrospinnability of the polymer blend, and it had negligible effects on fiber morphology and scaffold mechanical properties. The loading efficiency of kartogenin into electrospun membranes was nearly 100%, and no evidence of chemical reaction between kartogenin and the polymers was detected by Fourier transform infrared spectroscopy. Analysis of the released drug using high-performance liquid chromatography–photodiode array detection indicated an abundance of kartogenin and only a small amount of its major hydrolysis product. Kartogenin displayed a typical biphasic release profile, with approximately 30% being released within 24 h followed by a much slower, constant rate of release up to 28 days. Although additional development is needed to tune the release kinetics and address issues common to electrospun scaffolds (e.g., high fiber density), the results of this study demonstrated that a scaffold electrospun from biodegradable synthetic polymers is a suitable kartogenin delivery vehicle. Full article
(This article belongs to the Special Issue Polymeric Systems Loaded with Natural Bioactive Compounds)
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Figure 1

Figure 1
<p>Representative scanning electron micrographs of electrospun 12% PCL-PLGA (1:1): (<b>A</b>,<b>C</b>,<b>E</b>) control scaffolds contained no KGN and (<b>B</b>,<b>D</b>,<b>F</b>) experimental scaffolds contained 16.7 mg of KGN per gram of polymer blend. (<b>A</b>–<b>D</b>) Meshes are shown as fabricated and (<b>E,F</b>) after 28 days of soaking in PBS. Scale bar: (<b>A</b>,<b>B</b>) 10 μm; (<b>C</b>–<b>F</b>) 1 μm.</p> Full article ">Figure 2
<p>Mechanical properties of electrospun PCL-PLGA with and without KGN: (<b>A</b>) representative stress–strain curves and (<b>B</b>) material properties. Differences between control and KGN were not statistically significant. Error bars = ± one standard deviation.</p> Full article ">Figure 3
<p>FTIR spectra of pure KGN (powdered form), PCL-PLGA blend (electrospun mesh), and PCL-PLGA-KGN composite (electrospun mesh).</p> Full article ">Figure 4
<p>Kinetics of KGN release from PCL-PLGA (1:1) electrospun mesh into PBS. Conditions were 37 °C and orbital shaking at approximately 100 rpm.</p> Full article ">Figure 5
<p>Reversed-phase HPLC-PDA chromatograms of soaked scaffolds. PDA parameters: 200–350 nm. (<b>A</b>) Elution profile of the chemical standards (Sigma): PA, phthalic acid; 4ABP, 4-aminobiphenyl; KGN, kartogenin. (<b>B</b>) PBS blank extract (negative control). (<b>C</b>) The 12% scaffold, day 2 extract. For the day 2 extracts, KGN accounted for &gt;90% of the peaks detected by the PDA detector. Details of the extraction procedure are described in the Materials and Methods.</p> Full article ">
14 pages, 1997 KiB  
Article
Curcumin–Induced Stabilization of Protein–Based Nano-Delivery Vehicles Reduces Disruption of Zwitterionic Giant Unilamellar Vesicles
by Ogadimma D. Okagu, Raliat O. Abioye and Chibuike C. Udenigwe
Molecules 2022, 27(6), 1941; https://doi.org/10.3390/molecules27061941 - 17 Mar 2022
Cited by 3 | Viewed by 2745
Abstract
Curcumin-loaded native and succinylated pea protein nanoparticles, as well as zwitterionic giant unilamellar vesicles were used in this study as model bioactive compound loaded-nanoparticles and biomembranes, respectively, to assess bio-nano interactions. Curcumin-loaded native protein-chitosan and succinylated protein-chitosan complexes, as well as native protein-chitosan [...] Read more.
Curcumin-loaded native and succinylated pea protein nanoparticles, as well as zwitterionic giant unilamellar vesicles were used in this study as model bioactive compound loaded-nanoparticles and biomembranes, respectively, to assess bio-nano interactions. Curcumin-loaded native protein-chitosan and succinylated protein-chitosan complexes, as well as native protein-chitosan and succinylated protein-chitosan hollow, induced leakage of the calcein encapsulated in the giant unilamellar vesicles. The leakage was more pronounced with hollow protein-chitosan complexes. However, curcumin-loaded native protein and curcumin-loaded succinylated protein nanoparticles induced calcein fluorescence quenching. Dynamic light scattering measurements showed that the interaction of curcumin-loaded native protein, curcumin-loaded succinylated protein, native protein-chitosan, and succinylated protein-chitosan complexes with the giant unilamellar vesicles caused a major reduction in the size of the lipid vesicles. Confocal and widefield fluorescence microscopy showed rupturing of the unilamellar vesicles after treatment with native pea protein-chitosan and succinylated pea protein-chitosan complexes. The nature of interaction between the curcumin-loaded protein nanoparticles and the biomembranes, at the bio-nano interface, is influenced by the encapsulated curcumin. Findings from this study showed that, as the protein plays a crucial role in stabilizing the bioactive compound from chemical and photodegradation, the encapsulated nutraceutical stabilizes the protein nanoparticle to reduce its interaction with biomembranes. Full article
(This article belongs to the Special Issue Polymeric Systems Loaded with Natural Bioactive Compounds)
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Figure 1

Figure 1
<p>Leakage-induced fluorescence emission spectra of calcein, encapsulated in the GUV, after interaction with various concentrations of (<b>A</b>) curcumin-loaded succinylated pea protein, (<b>B</b>) curcumin-loaded native pea protein, (<b>C</b>) curcumin-loaded succinylated pea protein-chitosan, (<b>D</b>) curcumin-loaded native pea protein-chitosan, (<b>E</b>) hollow succinylated pea protein-chitosan, and (<b>F</b>) hollow native pea protein-chitosan complexes.</p> Full article ">Figure 2
<p>Percentage calcein leakage from the GUV, induced by (<b>a</b>) native protein-based nanoparticles and (<b>b</b>) succinylated protein-based nanoparticles, with different surface chemistry and physicochemical properties. Bars with similar letters represent mean values that are not significantly different at <span class="html-italic">p</span> &lt; 0.05.</p> Full article ">Figure 3
<p>Dynamic light scattering size distribution curve of calcein-loaded giant unilamellar vesicles (lGUV), before and after interaction with hollow (PPI/CHI and SPPI/CHI) and curcumin-loaded protein nanoparticles (CUR/PPI, CUR/SPPI, CUR/PPI/CHI and CUR/SPPI/CHI) and Triton X-100.</p> Full article ">Figure 4
<p>Confocal microscopy images of calcein-loaded GUV, after interaction with (<b>a</b>) CUR/SPPI, (<b>b</b>) CUR/PPI, (<b>c</b>) CUR/SPPI/CHI, (<b>d</b>) CUR/PPI/CHI, (<b>e</b>) SPPI/CHI, (<b>f</b>) PPI/CHI nanoparticles, and (<b>g</b>) calcein-loaded GUV, in the absence of nanoparticles, (<b>h</b>) calcein-loaded GUV after treatment with Triton X-100 (10%) positive control, and (<b>i</b>) GUV without calcein. Images in the first column were acquired at rhodamine B channel (GUV labeled with rhodamine), the second column is at calcein channel, and the third column is the merger of both. Scale bar is 2 µm.</p> Full article ">Figure 5
<p>Proposed nanoparticle-giant unilamellar vesicle interaction mechanisms.</p> Full article ">Scheme 1
<p>Preparation of hollow and curcumin-loaded protein and protein-chitosan nano-complexes with different physicochemical properties, as previously reported [<a href="#B1-molecules-27-01941" class="html-bibr">1</a>].</p> Full article ">
15 pages, 4737 KiB  
Article
Enhanced Sunscreen Effects via Layer-By-Layer Self-Assembly of Chitosan/Sodium Alginate/Calcium Chloride/EHA
by Chuntao Xu, Xuemin Zeng, Zujin Yang and Hongbing Ji
Molecules 2022, 27(3), 1148; https://doi.org/10.3390/molecules27031148 - 8 Feb 2022
Cited by 8 | Viewed by 3353
Abstract
The sunscreen nanocapsules were successfully synthesized by the way of layer-by-layer self-assembly using charged droplets (prepared by emulsification of LAD-30, Tween-80 and EHA (2-Ethylhexyl-4-dimethylaminobenzoate)) as templates. Chitosan/sodium alginate/calcium chloride were selected as wall materials to wrap EHA. The emulsions with the ratio of [...] Read more.
The sunscreen nanocapsules were successfully synthesized by the way of layer-by-layer self-assembly using charged droplets (prepared by emulsification of LAD-30, Tween-80 and EHA (2-Ethylhexyl-4-dimethylaminobenzoate)) as templates. Chitosan/sodium alginate/calcium chloride were selected as wall materials to wrap EHA. The emulsions with the ratio of Tween-80 to EHA (1:1) were stable. A stable NEI negative emulsion can be obtained when the ratio of Tween-80 and LAD-30 was 9:1. Chitosan solutions (50 kDa, 0.25 mg/mL) and sodium alginate solutions (0.5 mg/mL) were selected to prepare nanocapsules. The nanocapsules were characterized via some physico-chemical methods. Based on the synergistic effects of the electrostatic interaction between wall materials and emulsifiers, EHA was effectively encapsulated. DLS and TEM showed that the sunscreen nanocapsules were dispersed in a spherical shape with nano-size, with the increasing number of assembly layers, the size increased from 155 nm (NEI) to 189 nm (NEII) to 201 nm (NEIII) and 205 nm after solidification. The release studies in vitro showed sustained release behavior of the nanocapsules were observed with the increase of the number of deposition layers, implying a good coating effect. The sunscreen nanocapsules could control less than 50% the release of EHA after crosslinking of calcium chloride and sodium alginate, which also could effectively avoid the stimulation of the sun protection agent on the skin. Full article
(This article belongs to the Special Issue Polymeric Systems Loaded with Natural Bioactive Compounds)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>The influence of the stability of emulsion: (<b>a</b>) different emulsifiers, (<b>b</b>) the proportion of emulsifier and core material, (<b>c</b>) proportion of Tween/LAD-30.</p> Full article ">Figure 2
<p>NEI of (<b>a</b>) size, (<b>b</b>) zeta on the stability.</p> Full article ">Figure 3
<p>The effects of (<b>a</b>,<b>b</b>) molecular weight of Chitosan, (<b>c</b>) concentration of chitosanon the stability of NEII:.</p> Full article ">Figure 4
<p>The effects of (<b>a</b>) concentration of sodium alginate, (<b>b</b>) concentration of CaCl<sub>2</sub> on the stability of NEII.</p> Full article ">Figure 5
<p>Change on droplet: (<b>a</b>) size, (<b>b</b>) zeta.</p> Full article ">Figure 6
<p>TEM image of (<b>a</b>) NEI and (<b>b</b>) nanocapsule.</p> Full article ">Figure 7
<p>Cumulative release rate of EHA from sunscreen nanocapsules.</p> Full article ">Figure 8
<p>Transdermal accumulation of encapsulated and unwrapped EHA.</p> Full article ">Figure 9
<p>Skin accumulation of EHA.</p> Full article ">Figure 10
<p>Release kinetics models of EHA from the EHA nanocapsules, (<b>a</b>) Zero-order kinetics Models, (<b>b</b>) First-order kinetics Models, (<b>c</b>) Higuchi kinetics Models.</p> Full article ">Figure 11
<p>UV absorbability of the EHA nanocapsules.</p> Full article ">Scheme 1
<p>The synthetic route of the EHA nanocapsules by layer-by-layer self-assembly of chitosan/sodium alginate/calcium chloride/EHA.</p> Full article ">

Review

Jump to: Research

37 pages, 8600 KiB  
Review
Modification of Alginates to Modulate Their Physic-Chemical Properties and Obtain Biomaterials with Different Functional Properties
by Piotr Rosiak, Ilona Latanska, Paulina Paul, Witold Sujka and Beata Kolesinska
Molecules 2021, 26(23), 7264; https://doi.org/10.3390/molecules26237264 - 30 Nov 2021
Cited by 50 | Viewed by 8378
Abstract
Modified alginates have a wide range of applications, including in the manufacture of dressings and scaffolds used for regenerative medicine, in systems for selective drug delivery, and as hydrogel materials. This literature review discusses the methods used to modify alginates and obtain materials [...] Read more.
Modified alginates have a wide range of applications, including in the manufacture of dressings and scaffolds used for regenerative medicine, in systems for selective drug delivery, and as hydrogel materials. This literature review discusses the methods used to modify alginates and obtain materials with new or improved functional properties. It discusses the diverse biological and functional activity of alginates. It presents methods of modification that utilize both natural and synthetic peptides, and describes their influence on the biological properties of the alginates. The success of functionalization depends on the reaction conditions being sufficient to guarantee the desired transformations and provide modified alginates with new desirable properties, but mild enough to prevent degradation of the alginates. This review is a literature description of efficient methods of alginate functionalization using biologically active ligands. Particular attention was paid to methods of alginate functionalization with peptides, because the combination of the properties of alginates and peptides leads to the obtaining of conjugates with properties resulting from both components as well as a completely new, different functionality. Full article
(This article belongs to the Special Issue Polymeric Systems Loaded with Natural Bioactive Compounds)
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Figure 1

Figure 1
<p>Structure of alginates: (<b>a</b>) conformation of the oligosaccharide chain; (<b>b</b>) distribution of M and G blocks in the polysaccharide chain.</p> Full article ">Figure 2
<p>Probable structure of the complex formed by binding of the Ca<sup>2+</sup> ion with L-guluronic acid residues.</p> Full article ">Figure 3
<p>P Possible structures of alginate chelates with Ca<sup>2+</sup>: (<b>a</b>) GG/GG, (<b>b</b>) MG/MG, (<b>c</b>) GG/MG.</p> Full article ">Figure 4
<p>Acid-catalyzed degradation of alginic acid.</p> Full article ">Figure 5
<p>Base catalyzed degradation of alginate (β-elimination).</p> Full article ">Figure 6
<p>Acetylation of alginate using a mixture of pyridine/acetic anhydride. Gel acetylation: M = Ca<sup>2+</sup> or TBA<sup>+</sup>. Acetylation of a homogeneous system in DMSO/TBAF, M = TBA<sup>+</sup>, M’= -H<sup>+</sup> or Na<sup>+</sup>.</p> Full article ">Figure 7
<p>Phosphorylation of alginates.</p> Full article ">Figure 8
<p>Preparation of sulphate alginate derivatives using chlorosulfonic acid.</p> Full article ">Figure 9
<p>Formation of sulphate alginate derivatives using DCC and sulfuric acid.</p> Full article ">Figure 10
<p>T Formation of sulphate derivatives of alginates using a mixture of NaHSO<sub>3</sub> and NaNO<sub>2</sub>.</p> Full article ">Figure 11
<p>Oxidation of sodium alginate.</p> Full article ">Figure 12
<p>Reductive amination of oxidized sodium alginate.</p> Full article ">Figure 13
<p>Synthesis of PEG-ylated alginate derivative.</p> Full article ">Figure 14
<p>Esterification of alginates with alcohols.</p> Full article ">Figure 15
<p>Activation of the carboxyl group using carbodiimide derivatives and subsequent reaction with nucleophilic reagents.</p> Full article ">Figure 16
<p>Synthesis of alginic acid esters using alkyl halides.</p> Full article ">Figure 17
<p>Synthesis of amides of alginates in the reaction of propylene glycol esters of alginates with amines.</p> Full article ">Figure 18
<p>Formation of <span class="html-italic">N</span>-octylamide of alginic acid using EDC as a condensing agent.</p> Full article ">Figure 19
<p>Ugi multi-component reaction for the preparation of amide alginate derivatives.</p> Full article ">Figure 20
<p>Synthesis of alginate-peptide conjugate by alginate-S-S-y intermediate.</p> Full article ">
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