Auto-associative amphiphilic polysaccharides as drug delivery systems

Amphiphilic hydroxyethyl starch-based nanoparticles carrying linoleic acid modified berberine inhibit the expression of krasv12 oncogene in zebrafish

Cancer is one of the most lethal diseases all over the world. Despite that many drugs have been developed for cancer therapy, they still suffer from various limitations including poor treating efficacy, toxicity to normal human cells, and the emergence of multidrug resistance. In this study, the amphiphilic LHES polymers were prepared using hydroxyethyl starch (HES) and linoleic acid as starting materials. The content and substitution degree of linoleic acid groups in LHES polymers were analyzed. The LHES polymers were used for fabricating LHES-B nanoparticles carrying a linoleic acid modified berberine derivative (L-BBR). The LHES-B nanoparticles showed high drug loading efficiency (29%) and could quickly release L-BBR under acidic pH condition (pH = 4.5). Biological investigations revealed that LHES-B nanoparticles significantly inhibited the proliferation of HepG2 cells and exhibited higher cytotoxicity than L-BBR. In a transgenic Tg(fabp10:rtTA2s-M2; TRE2:EGFP-krasv12) zebrafish model, LHES-B nanoparticles obviously inhibited the expression of krasv12 oncogene. These results indicated that LHES carriers could improve the anticancer activity of L-BBR, and the synthesized LHES-B nanoparticles showed great potential as anticancer drug.

Synthesis and self-assembling of hyaluronan grafted with ceramide NP for topical drug delivery

In this work, amphiphilic hyaluronan was synthesized by grafting succinylated N-oleoyl-phytosphingosine via esters bonds. Succinylated N-oleoyl-phytosphingosine (sCER) was first prepared by esterification of hydroxyl moieties of the ceramide with succinic anhydride. The esterification of hyaluronan was governed by crowding effect. The oligomeric HA-sCER derivatives exhibited a strong self-aggregation as evidenced by a very low critical aggregation concentration (1.9 μg mL-1), higher pyrene binding constant (KB), and the smallest particle size (30 nm) in solution. The self-aggregation properties demonstrated to be a function of the substitution degree and molecular weight of HA. The prepared derivatives were non-cytotoxic towards cell lines NIH-3T3. Nanoparticles prepared using oligomeric HA-sCER derivatives improved the penetration of Nile red dye through the stratum corneum due to their smaller size (≤50 nm). The fluorescence intensity localized at the stratum corneum was higher for oligomeric HA-sCER. A significant inhibition of the pro-inflammatory cytokine interleukin-6 production was observed in vitro in macrophages differentiated from THP-1 cells. These findings showed that HA-sCER constituted a promising active ingredient for cosmetics use.

Polysaccharides-based nanocarriers enhance the anti-inflammatory effect of curcumin

Curcumin (CUR) has been discovered to have many biological activities, including anti-inflammatory, anti-cancer, anti-oxygenation, anti-human immunodeficiency virus, anti-microbial and exhibits a good effect on the prevention and treatment of many diseases. However, the limited properties of CUR, including the poor solubility, bioavailability and instability caused by enzymes, light, metal irons, and oxygen, have compelled researchers to turn their attention to drug carrier application to overcome these drawbacks. Encapsulation may provide potential protective effects to the embedding materials and/or have a synergistic effect with them. Therefore, nanocarriers, especially polysaccharides-based nanocarriers, have been developed in many studies to enhance the anti-inflammatory capacity of CUR. Consequently, it's critical to review current advancements in the encapsulation of CUR using polysaccharides-based nanocarriers, as well as further study the potential mechanisms of action where polysaccharides-based CUR nanoparticles (the complex nanoparticles/Nano CUR-delivery systems) exhibit their anti-inflammatory effects. This work suggests that polysaccharides-based nanocarriers will be a thriving field in the treatment of inflammation and inflammation-related diseases.

Microstructured click hydrogels for cell contact guidance in 3D

The topography of the extracellular matrix (ECM) is a major biophysical regulator of cell behavior. While this has inspired the design of cell-instructive biomaterials, the ability to present topographic cues to cells in a true 3D setting remains challenging, particularly in ECM-like hydrogels made from a single polymer. Herein, we report the design of microstructured alginate hydrogels for injectable cell delivery and show their ability to orchestrate morphogenesis via cellular contact guidance in 3D. Alginate was grafted with hydrophobic cyclooctyne groups (ALG-K), yielding amphiphilic derivatives with self-associative potential and ionic crosslinking ability. This allowed the formation of microstructured ALG-K_H hydrogels, triggered by the spontaneous segregation between hydrophobic/hydrophilic regions of the polymer that generated 3D networks with stiffer microdomains within a softer lattice. The azide-reactivity of cyclooctynes also allowed ALG-K functionalization with bioactive peptides via cytocompatible strain-promoted azide-alkyne cycloaddition (SPAAC). Hydrogel-embedded mesenchymal stem cells (MSCs) were able to integrate spatial information and to mechano-sense the 3D topography, which regulated cell shape and stress fiber organization. MSCs clusters initially formed on microstructured regions could then act as seeds for neo-tissue formation, inducing cells to produce their own ECM and self-organize into multicellular structures throughout the hydrogel. By combining 3D topography, click functionalization, and injectability, using a single polymer, ALG-K hydrogels provide a unique cell delivery platform for tissue regeneration.

Role of Hydrophobic Associations in Self-Healing Hydrogels Based on Amphiphilic Polysaccharides

Self-healing hydrogels have the ability to recover their original properties after the action of an external stress, due to presence in their structure of reversible chemical or physical cross-links. The physical cross-links lead to supramolecular hydrogels stabilized by hydrogen bonds, hydrophobic associations, electrostatic interactions, or host-guest interactions. Hydrophobic associations of amphiphilic polymers can provide self-healing hydrogels with good mechanical properties, and can also add more functionalities to these hydrogels by creating hydrophobic microdomains inside the hydrogels. This review highlights the main general advantages brought by hydrophobic associations in the design of self-healing hydrogels, with a focus on hydrogels based on biocompatible and biodegradable amphiphilic polysaccharides.

One-Pot Synthesis of Amphiphilic Biopolymers from Oxidized Alginate and Self-Assembly as a Carrier for Sustained Release of Hydrophobic Drugs

In this paper, we developed an organic solvent-free, eco-friendly, simple and efficient one-pot approach for the preparation of amphiphilic conjugates (Ugi-OSAOcT) by grafting octylamine (OCA) to oxidized sodium alginate (OSA). The optimum reaction parameters that were obtained based on the degree of substitution (DS) of Ugi-OSAOcT were a reaction time of 12 h, a reaction temperature of 25 °C and a molar ratio of 1:2.4:3:3.3 (OSA:OCA:HAc:TOSMIC), respectively. The chemical structure and composition were characterized by Fourier transform infrared spectroscopy (FTIR), ¹H nuclear magnetic resonance (¹H NMR), X-ray diffraction (XRD), thermogravimetry analyser (TGA), gel permeation chromatography (GPC) and elemental analysis (EA). It was found that the Ugi-OSAOcT conjugates with a CMC value in the range of 0.30–0.085 mg/mL could self-assemble into stable and spherical micelles with a particle size of 135.7 ± 2.4–196.5 ± 3.8 nm and negative surface potentials of −32.8 ± 0.4–−38.2 ± 0.8 mV. Furthermore, ibuprofen (IBU), which served as a model poorly water-soluble drug, was successfully incorporated into the Ugi-OSAOcT micelles by dialysis method. The drug loading capacity (%DL) and encapsulation efficiency (%EE) of the IBU-loaded Ugi-OSAOcT micelles (IBU/Ugi-OSAOcT = 3:10) reached as much as 10.9 ± 0.4–14.6 ± 0.3% and 40.8 ± 1.6–57.2 ± 1.3%, respectively. The in vitro release study demonstrated that the IBU-loaded micelles had a sustained and pH-responsive drug release behavior. In addition, the DS of the hydrophobic segment on an OSA backbone was demonstrated to have an important effect on IBU loading and drug release behavior. Finally, the in vitro cytotoxicity assay demonstrated that the Ugi-OSAOcT conjugates exhibited no significant cytotoxicity against RAW 264.7 cells up to 1000 µg/mL. Therefore, the amphiphilic Ugi-OSAOcT conjugates synthesized by the green method exhibited great potential to load hydrophobic drugs, acting as a promising nanocarrier capable of responding to pH for sustained release of hydrophobic drugs.

Stimuli-Free Transcuticular Delivery of Zn Microelement Using Biopolymeric Nanovehicles: Experimental, Theoretical, and In Planta Studies

This paper reports one-step synthesis of polysaccharide-based nanovehicles, capable of transporting ionic zinc via plant cuticle without auxiliary stimulation. Delivery of highly hydrophilic nutritive microelements via the hydrophobic cuticle of plant foliage is one of the major challenges in modern agriculture. In traditional nutrition via roots, up to 80% of microelements permeate to soil and get wasted; therefore, foliar treatment is an environmentally and economically preferable alternative. Carboxymethyl cellulose (CMC) was modified to amphiphilic N-octylamide-derivative (CMC-8), which spontaneously self-assemble to nanovehicles. It was found that hydrophobic substituents endow a biopolymer with unexpected affinity toward a hydrophilic payload. CMC-8 nanovehicles effectively encapsulated ionic zinc (ZnSO₄) and delivered it upon foliar application to pepper (Capsicum annuum) and tomato (Solanum lycopersicum) plants. Zinc uptake and translocation in plants were monitored by SEM-EDS and fluorescence microscopic methods. In planta monitoring of the carrier was done by labeling nanovehicles with fluorescent carbon dots. Three-dimensional (3-D) structural modeling and conformational dynamics explained the CMC-8 self-assembly mechanism and zinc coordination phenomenon upon introduction of hydrophobic substituents.

(Macro)molecular self-assembly for hydrogel drug delivery

Hydrogels prepared via self-assembly offer scalable and tunable platforms for drug delivery applications. Molecular-scale self-assembly leverages an interplay of attractive and repulsive forces; drugs and other active molecules can be incorporated into such materials by partitioning in hydrophobic domains, affinity-mediated binding, or covalent integration. Peptides have been widely used as building blocks for self-assembly due to facile synthesis, ease of modification with bioactive molecules, and precise molecular-scale control over material properties through tunable interactions. Additional opportunities are manifest in stimuli-responsive self-assembly for more precise drug action. Hydrogels can likewise be fabricated from macromolecular self-assembly, with both synthetic polymers and biopolymers used to prepare materials with controlled mechanical properties and tunable drug release. These include clinical approaches for solubilization and delivery of hydrophobic drugs. To further enhance mechanical properties of hydrogels prepared through self-assembly, recent work has integrated self-assembly motifs with polymeric networks. For example, double-network hydrogels capture the beneficial properties of both self-assembled and covalent networks. The expanding ability to fabricate complex and precise materials, coupled with an improved understanding of biology, will lead to new classes of hydrogels specifically tailored for drug delivery applications.

Recent Development of Alginate-Based Materials and Their Versatile Functions in Biomedicine, Flexible Electronics, and Environmental Uses

Alginate is a natural polysaccharide that is easily chemically modified or compounded with other components for various types of functionalities. The alginate derivatives are appealing not only because they are biocompatible so that they can be used in biomedicine or tissue engineering but also because of the prospering bioelectronics that require various biomaterials to interface between human tissues and electronics or to serve as electronic components themselves. The study of alginate-based materials, especially hydrogels, have repeatedly found new frontiers over recent years. In this Review, we document the basic properties of alginate, their chemical modification strategies, and the recent development of alginate-based functional composite materials. The newly thrived functions such as ionically conductive hydrogel or 3D or 4D cell culturing matrix are emphasized among other appealing potential applications. We expect that the documentation of relevant information will stimulate scientific efforts to further develop biocompatible electronics or smart materials and to help the research domain better address the medicine, energy, and environmental challenges faced by human societies.

Recent updates in the polysaccharides-based Nano-biocarriers for drugs delivery and its application in diseases treatment: A review

With people's increasing awareness of diseases treatment, the researchers began to focus on drug delivery to the exact site of action at the optimal rate. Some researchers have proved that many nanostructures loaded with drugs are significantly better than conventional nanostructures. However, the materials from which the nanostructure determines its performance. To use it as a pharmaceutical ingredient, it must meet strict safety regulatory standards worldwide. Therefore, people's attention has paid to easily available natural substances. As far as we know, bioactive polysaccharides are excellent candidates for realizing these purposes. To be precise, due to the natural availability of polysaccharides, it has been widely used in the research of Nano-biocarriers loaded with drugs. Based on the above analysis, the nanomaterials developed through the laboratory have great potential for upgrading to market products. Therefore, it is of great significance to review the latest progress of polysaccharide-based Nano-biocarriers in drug delivery and their application in diseases treatment. In this work, we focused on the preparation of polysaccharides-based Nano-biocarriers, commonly used polysaccharides for preparing Nano-biocarriers, and drugs loaded on polysaccharides-based Nano-biocarriers to treat diseases. Shortly, polysaccharide-based Nano-biocarriers will be increasingly used in drug delivery and treatment of diseases.

Recent advances in guar gum based drug delivery systems and their administrative routes

Guar gum-based drug carrier systems have gained attention for the delivery of various therapeutic agents via different administration routes for attaining controlled and sustained release. Guar gum offers a safe and effective system for drug delivery due to its natural occurrence, easy availability, biocompatibility, and biodegradability, besides simple and mild preparation techniques. Furthermore, the possibility of using various routes such as oral, buccal, transdermal, intravenous, and gene delivery further diversify guar gum applications in the biomedical field. This review delineates the recent investigation on guar gum-based drug carrier systems like hydrogels, nanoparticles, nanocomposites, and scaffolds along with their related delivery routes. Also, the inclusion of data of the loading and subsequent release of the drugs enables to explore the noble and improved drug targeting therapies.

Cellulose-based thermo-enhanced fluorescence micelles

Recently, cellulose-based stimuli-responsive nanomaterials have received significant attention because of its natural source and biocompatibility. In this study, cellulose-graft-poly(nisopropylacrylamide)-co-2-methyl-acrylic acid 2-carbazol-9-yl-ethyl ester (cellulose-g-(PNIPAAm&PCz)) block polymers were successfully synthesized by homogeneous atom transfer radical polymerization (ATRP) in LiCl/N,N-dimethylacetamide (DMAc) dissolution system. The block polymers showed different properties due to the different PCz content. The block polymer with low PCz content (cellulose-g-(PNIPAAm&PCz)1) was dispersed in water at 25 °C and self-assembled into micelles at 37 °C. On the other hand, the block polymer with high PCz content (cellulose-g-(PNIPAAm&PCz)2) was dissolved in DMF, THF, DMSO firstly, and dialyzed at 25 °C, 37 °C and 60 °C respectively to obtain the micelles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) indicated that the distribution range of micelles formed by cellulose-g-(PNIPAAm&PCz)1 was narrower than cellulose-g-(PNIPAAm&PCz)2. And the sizes of the micelles formed by cellulose-g-(PNIPAAm&PCz)2 had little difference under different solvents, but became bigger with the temperature increased. The micelles displayed thermo-enhanced fluorescence due to the thermal-driven chain dehydration of the grafted PNIPAAm brushes, which is contrary to the decrease of the fluorescence of the monomer when the temperature increased. The results provided a potential for the application of cellulose-based stimuli-responsive micelles in the field of drug delivery and fluorescent probes.

A review on grafting of hydroxyethylcellulose for versatile applications

Hydroxyethylcellulose (HEC) is a biocompatible, biodegradable, nontoxic, hydrophilic, non- ionic water soluble derivative of cellulose. It is broadly used in biomedical field, paint industry, as a soil amendment in agriculture, coal dewatering, cosmetics, absorbent pads, wastewater treatment and gel electrolyte membranes. Industrial uses of HEC can be extended by the its grafting with different polymers including poly acrylic acid, polyacrylamide, polylactic acid, polyethyleneglycol, polydimethyleamide, polycaprolactone, polylactic acid and dimethylamino ethylmethacrylate. This permits the formation of new biomaterials with improved properties and versatile applications. In this article, a comprehensive overview of graft copolymers of HEC with other polymers/compounds and their applications in drug delivery, stimuli sensitive hydrogels, super absorbents, personal hygiene products and coal dewatering is presented.

Electrolyte and pH-sensitive amphiphilic alginate: synthesis, self-assembly and controlled release of acetamiprid

In this study, a pH-responsive amphiphilic alginate (Ugi-Alg) was synthesized via Ugi reaction without using a catalyst. The structure of Ugi-Alg was confirmed by FT-IR and ¹H NMR spectroscopy. Amphiphilic alginate can form micelles in an aqueous medium due to it's amphiphilic nature.. The impacts of Na⁺ concentration and pH on the micelle size were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The dynamic light scattering observations showed that micelle size increases with the decrease in Na⁺ concentration in aqueous solution. However, the micelle size decreases first and then increases as the pH value decreases from 5.3 to 2.0. Transmission electron microscopy confirmed that the mean size of micelles is 30–200 nm. In addition, a model hydrophobic pesticide (acetamiprid) was loaded in the micelles. The encapsulation efficiency and release behavior of micelles were studied, which could be controlled by Na⁺ concentration and pH. The results indicated that encapsulation efficiency of acetamiprid increases from 55% to 96% due to the increase in Na⁺ concentration from 0.01 M to 0.3 M. Moreover, with the decrease in pH from 5.3 to 2.0, encapsulation efficiency increases from 55% to 80%. Furthermore, the data of acetamiprid release kinetics could be well-fitted by the Weibull model.

Schematic of Ugi-Alg aggregation in aqueous solution of different NaCl concentrations and pH values.

Robust oil-core nanocapsules with hyaluronate-based shells as promising nanovehicles for lipophilic compounds

The design of nanodelivery systems has been recently considered as a solution to the major challenge in pharmaceutical research - poor bioavailability of lipophilic drugs. Nanocapsules with liquid oil cores and shells based on amphiphilic polysaccharides were developed here as robust carriers of hydrophobic active compounds. A series of modified charged hyaluronates were synthesized and used as stabilizing shells ensuring also the biocompatibility of the nanocapsules that is crucial for applications related to the delivery of lipophilic drugs in vivo. Importantly, the oil nanodroplets were found to be stably suspended in water for at least 15 months without addition of low molar mass surfactants. Moreover, their size and stability may be tuned by varying the relative content of hydrophobic and hydrophilic groups in the hyaluronate derivatives as was confirmed by dynamic light scattering and nanoparticle tracking analysis as well as electron microscopy. In vivo studies demonstrated that hyaluronate-based nanocapsules accumulated preferentially in the liver as well as in the lungs. Moreover, their accumulation was dramatically potentiated in endotoxemic mice. In vitro studies showed that the nanocapsules were taken up by liver sinusoidal endothelial cells and by mouse lung vascular endothelial cells. Importantly, the capsules were found to be nontoxic in an acute oral toxicity experiment even at a dose of 2000 mg per kg b.w. Biocompatible hyaluronate-based nanocapsules with liquid cores described herein represent a promising and tunable nanodelivery system for lipophilic active compounds via both oral and intravenous administration.

Enzymatic and acidic degradation of high molecular weight dextran into low molecular weight and its characterizations using novel Diffusion-ordered NMR spectroscopy

Low molecular weight fractions were derived from native high molecular weight dextran produced by Leuconostoc mesenteroides KIBGE-IB26. Structural characterization of native and low molecular weight fractions obtained after acidic and enzymatic hydrolysis was done using FTIR and NMR spectroscopy. The molecular weight was estimated using Diffusion Ordered NMR spectroscopy. Native dextran (892kDa) is composed of α-(1→6) glycosidic linkage along with α-(1→3) branching. Major proportion of 528kDa dextran was obtained after prolong enzymatic hydrolysis however, an effective acidic treatment at pH-1.4 up to 02 and 04h of exposure resulted in the formation of 77kDa and 57kDa, respectively. The increment in pH from 1.4 to 1.8 lowered the hydrolysis efficiency and resulted in the formation of 270kDa dextran fraction. The results suggest that derived low molecular weight water soluble fractions can be utilized as a drug delivery carrier along with multiple application relating pharmaceutical industries.

Tailoring the supramolecular structure of amphiphilic glycopolypeptide analogue toward liver targeted drug delivery systems

Amphiphilic glycopolypeptide analogues have harboured great importance in the development of targeted drug delivery systems. In this study, lactosylated pullulan-graft-arginine dendrons (LP-g-G3P) was synthesized using Huisgen azide-alkyne 1,3-dipolar cycloaddition between lactosylated pullulan and generation 3 arginine dendrons bearing Pbf and Boc groups on the periphery. Hydrophilic lactosylated pullulan was selected for amphiphilic modification, aiming at specific lectin recognition. Macromolecular structure of LP-g-G3P combined alkyl, aromatic, and peptide dendritic hydrophobic moieties and was able to self-assemble spontaneously into core-shell nanoarchitectures with small particle sizes and low polydispersity in the aqueous media, which was confirmed by CAC, DLS and TEM. Furthermore, the polyaromatic anticancer drug (doxorubicin, DOX) was selectively encapsulated in the hydrophobic core through multiple interactions with the dendrons, including π-π interactions, hydrogen bonding and hydrophobic interactions. Such multiple interactions had the merits of enhanced drug loading capacity (16.89±2.41%), good stability against dilution, and excellent sustained release property. The cell viability assay presented that LP-g-G3P nanoparticles had an excellent biocompatibility both in the normal and tumor cells. Moreover, LP-g-G3P/DOX nanoparticles could be effectively internalized into the hepatoma carcinoma cells and dramatically inhibited cell proliferation. Thus, this approach paves the way to develop amphiphilic and biofunctional glycopolypeptide-based drug delivery systems.

Redox-sensitive self-assembled nanoparticles based on alpha-tocopherol succinate-modified heparin for intracellular delivery of paclitaxel

To remedy the problems riddled in cancer chemotherapy, such as poor solubility, low selectivity, and insufficient intra-cellular release of drugs, novel heparin-based redox-sensitive polymeric nanoparticles were developed. The amphiphilic polymer, heparin-alpha-tocopherol succinate (Hep-cys-TOS) was synthesized by grafting hydrophobic TOS to heparin using cystamine as the redox-sensitive linker, which could self-assemble into nanoparticles in phosphate buffer saline (PBS) with low critical aggregation concentration (CAC) values ranging from 0.026 to 0.093mg/mL. Paclitaxel (PTX)-loaded Hep-cys-TOS nanoparticles were prepared via a dialysis method, exhibiting a high drug-loading efficiency of 18.99%. Physicochemical properties of the optimized formulation were characterized by dynamic light scattering (DLS), transmission electron microscope (TEM) and differential scanning calorimetry (DSC). Subsequently, the redox-sensitivity of Hep-cys-TOS nanoparticles was confirmed by the changes in size distribution, morphology and appearance after dithiothreitol (DTT) treatment. Besides, the in vitro release of PTX from Hep-cys-TOS nanoparticles also exhibited a redox-triggered profile. Also, the uptake behavior and pathways of coumarin 6-loaded Hep-cys-TOS nanoparticles were investigated, suggesting the nanoparticles could be taken into MCF-7 cells in energy-dependent, caveolae-mediated and cholesterol-dependent endocytosis manners. Later, MTT assays of different PTX-free and PTX-loaded formulations revealed the desirable safety of PTX-free nanoparticles and the enhanced anti-cancer activity of PTX-loaded Hep-cys-TOS nanoparticles (IC₅₀=0.79μg/mL). Apoptosis study indicated the redox-sensitive formulation could induce more apoptosis of MCF-7 cells than insensitive one (55.2% vs. 41.7%), showing the importance of intracellular burst release of PTX. Subsequently, the hemolytic toxicity confirmed the safety of the nanoparticles for intravenous administration. The results indicated the developed redox-sensitive nanoparticles were promising as intracellular drug delivery vehicles for cancer treatment.

Dextran-g-lauric acid as IKK complex inhibitor carrier

Copolymeric micelles made from dextran-g-lauric acid with different molecular weights were optimized to carry IκB kinase-β inhibitor, IMD-0354, for melanoma treatment.

Synthesis, self-assembly, and in vitro toxicity of fatty acids-modified Bletilla striata polysaccharide

Hydrophobic modification of Bletilla striata polysaccharide (BSP) was performed by grafting fatty acids to BSP backbone and then characterized on their physicochemical properties. All neutral derivatives were able to self-assemble into spherical particles within the size range of 250-400 nm, their size and critical micelle concentration decreased with increasing hydrophobicity and substitution degree of the fatty acids. Also, the BSP-stearic acid conjugates showed a preferable performance on hemolysis test and cytotoxicity analysis on HepG2 cells, which suggested their potential application as a drug delivery vector.

Synthesis, characterization, and solution behavior of pullulan functionalized with tertiary amino groups

The synthesis of cationic amphiphilic pullulan having dimethylaminopropyl groups was performed in dimethyl sulfoxide using N, N′-carbonyldiimidazole as activator. The pullulan derivatives with three different substitution degrees were characterized by FTIR, 1H and 13C NMR, elemental analysis, and conductometric titrations. The aggregates characteristics were determined by steady-state fluorescence (critical aggregation concentration and polarity) and capillary viscometry measurements. Their behavior in aqueous dilute and semidilute solutions was investigated by viscosimetric experiments and fluorescence technique over the concentration range of 0.01–10 g dL−1, as a function of the degree of substitution with pendant groups. Intrinsic viscosity determined using Wolf equations provided information on the conformation of polymer chains. The results highlight the appearance of intramolecular and intermolecular aggregates and the dependence of their characteristics on the degree of substitution with pendant groups.