Synthesis of chitosan-graft-β-cyclodextrin for improving the loading and release of doxorubicin in the nanopaticles

Advances in Chitosan Derivatives: Preparation, Properties and Applications in Pharmacy and Medicine

Chitosan (CS) derivatives have been extensively investigated to enhance the physicochemical and biological properties of CS, such as its solubility, biocompatibility, and bioactivity, which are required in various areas of pharmacy and medicine. The present work emphasizes the ongoing research and development in this field, suggesting that the further exploration of CS derivatives could lead to innovative solutions that benefit society. The physicochemical properties, biological activities, methods of preparation, advantages, limitations, intended application areas, and realized practical implementations of particular CS derivatives are summarized and discussed herein. Despite the numerous promising attributes of CS derivatives as reported in this paper, however, challenges like target selectivity, standardization (purity, chitosan structural variability), and cost-effectiveness still need addressing for widespread implementation, especially in drug delivery. Therefore, basic research studies still prevail in CS drug delivery systems. However, for specific applications such as wound healing and tissue engineering, implementations of CS derivatives in practice are found to be more frequent. To obtain a more complex view of the topic, information from the scientific papers reviewed is supplemented with information from actual patents and clinical studies. Both basic research advances and the most successful and important medical implementations of CS derivatives are discussed concerning further challenges and future perspectives.

A practical manner to GTR recycling in waste-HDPE/ABS

Waste high-density polyethylene (w-HDPE)/ acrylonitrile–butadiene–styrene (ABS)/ground tire rubber (GTR) have been melt blended by two-roll milling. Ternary blends of w-HDPE/ABS/GTR have been observed to be incompatible in the composition range studied which revealed in the deteriorated mechanical properties. Two main types of compatibilizers such as an experimental olefin-maleic anhydride copolymer based one synthesized by the authors and a commercial maleic anhydride grafted polypropylene (MA-g-PP) have been chosen for enhancing compatibility between the components ergo the mechanical properties. For characterizing tensile and impact properties of the blends mechanical tests have been carried out besides the scanning electron microscopy (SEM), X-ray diffraction and Fourier transform infrared spectroscopy. The most advantageous result in industrial practice can be that the experimental additive allows to apply higher GTR concentration ergo gives the opportunity to recycle higher level of GTR.

Impact of side reactions on molar mass distribution, unsaturation level and branching density in solution free radical polymerization of n-butyl acrylate under well-defined lab-scale reactor conditions

The paper describes the influence of side reactions in isothermal solution free-radical polymerization of n-butyl acrylate accounting for chain-length dependent diffusional limitations on termination.

Devulcanization of ground tire rubber: microwave and thermomechanical approaches

We devulcanized ground tire rubber (GTR) in a laboratory microwave oven and an internal mixer, measured the soluble content and the cross-link density of the samples, and then used Horikx's analysis. The results showed that microwave treatment caused severe degradation of the polymer chains, while in the case of thermomechanical devulcanization, the selective scission of covalent cross-links is more common. Four devulcanized ground tire rubber (dGTR) samples were chosen for further study and three groups of samples were produced: dGTR samples containing vulcanizing agents and different amounts of paraffin oil (dGTR-based mixtures), natural rubber-based rubber mixtures with different dGTR contents and reference rubber mixtures with dGTR-based mixtures (increased vulcanizing agent contents). Cure characteristics showed a plasticizer-like effect of dGTR. Tensile and tear strength decreased drastically with increasing dGTR content; however, elongation at break values did not follow such a trend. Mechanical properties improved with increased vulcanizing agent contents. The examined properties of the samples improved even further with the use of thermomechanically devulcanized samples. Horikx's analysis showed that this is attributable to moderate polymer chain scission.

Biomaterials for Interfacing Cell Imaging and Drug Delivery: An Overview

This feature article provides an overview of different kinds of futuristic biomaterials which have the potential to be used for fluorescent imaging and drug delivery, often simultaneously. The synthesis route or preparation process, fluorescence property, release profile, biocompatibility, bioimaging, and mechanistic approaches are vividly discussed. These include bioimaging with fluorescently doped quantum dots, mesoporous silica, noble metals, metal clusters, hydrophilic/hydrophobic polymers, semiconducting polymer dots, carbon/graphene dots, dendrimers, fluorescent proteins, and other nanobiomaterials. Another section discusses the controlled and targeted drug, gene, or biologically active material delivery using various vehicles such as micelles, 2D nanomaterials, organic nanoparticles, polymeric nanohybrids, and chemically modified polymers. In the last section, we discuss biomaterials, which can deliver biologically active molecules, and imaging the cell/tissue.

Bilayer Nanocarriers with Protein-Acid Conjugation for Prolonged Release and Enhanced Anticancer Effects

Conventional chemotherapy, because of the high dose to keep the drug above the minimum effective concentration, possesses severe side effects and brings extra pain to patients. A controlled release drug delivery system, which is a bilayer self-assembled nanoparticle (NP) in this study, can solve this problem. Zein, a biodegradable natural protein from corn, was selected for the first layer of the drug encapsulation. The second layer was formed via the reversible ionic hydrogen bonds between zein and folic acid (FA), which was selected because of the two carboxylic acids and one amine group in its simple structure. Doxorubicin (DOX), a popular anticancer drug, was selected as the drug model to form the bilayer drug nanoencapsulation FA-NP-DOX. The in vitro controlled release profile of FA-NP-DOX was obtained. The in vivo pharmacokinetics and anticancer activity of FA-NP-DOX in tumor-xenografted animal models were also conducted. Compared to the zein nanoencapsulation of DOX (NP-DOX) and pure DOX, FA-NP-DOX showed comparable in vitro cytotoxicity but much longer in vitro controlled release time and in vivo circulation time. Both FA-NP-DOX and NP-DOX showed enhanced therapeutical efficiency in vivo than pure DOX. It is concluded that the bilayer self-assembled NP of zein and FA highly prolonged the controlled release and enhanced the therapeutic efficiency of the anticancer drug.

Biocompatible crosslinked β-cyclodextrin nanoparticles as multifunctional carriers for cellular delivery

Nanoparticle-based biomedicine has received enormous attention for theranostic applications, as these systems are expected to overcome several drawbacks of conventional therapy. Herein, effective and controlled drug delivery systems with on-demand release abilities and biocompatible properties are used as a versatile and powerful class of nanocarriers. We report the synthesis of a novel biocompatible and multifunctional material, entirely consisting of covalently crosslinked organic molecules. Specifically, β-cyclodextrin (CD) precursors were crosslinked with rigid organic linker molecules to obtain small (∼150 nm), thermally stable and highly water-dispersible nanoparticles with an accessible pore system containing β-CD rings. The nanoparticles can be covalently labeled with dye molecules to allow effective tracking in in vitro cell experiments. Rapid sugar-mediated cell-uptake kinetics were observed with HeLa cells, revealing exceptional particle uptake within only 30 minutes. Additionally, the particles could be loaded with different cargo molecules showing pH-responsive release behavior. Successful nuclei staining with Hoechst 33342 dye and effective cell killing with doxorubicin cargo molecules were demonstrated in live-cell experiments, respectively. This novel nanocarrier concept provides a promising platform for the development of controllable and highly biocompatible theranostic systems.

Sulfonato-β-Cyclodextrin Mediated Supramolecular Nanoparticle for Controlled Release of Berberine

A kind of supramolecular assemblies was constructed from two water-soluble and biocompatible saccharides, sulfonato-β-cyclodextrin (SCD) and chitosan, and characterized by dynamic light scattering (DLS), UV-vis, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that such nanoparticles presented good stability and controlled loading/release property, which enabled them as good drug carrier for berberine chloride (BE), a representative drug from traditional Chinese herbs. That is, the nanoparticles can load BE with high stability in a low-pH environment like that of the stomach but released BE when moved to a high-pH environment like that of the intestine.

Chitosan Derivatives: Introducing New Functionalities with a Controlled Molecular Architecture for Innovative Materials

The functionalization of polymeric substances is of great interest for the development of innovative materials for advanced applications. For many decades, the functionalization of chitosan has been a convenient way to improve its properties with the aim of preparing new materials with specialized characteristics. In the present review, we summarize the latest methods for the modification and derivatization of chitin and chitosan under experimental conditions, which allow a control over the macromolecular architecture. This is because an understanding of the interdependence between chemical structure and properties is an important condition for proposing innovative materials. New advances in methods and strategies of functionalization such as the click chemistry approach, grafting onto copolymerization, coupling with cyclodextrins, and reactions in ionic liquids are discussed.

Boronic acid as an efficient anchor group for surface modification of solid polyvinyl alcohol

We report the use of boronic acid as an anchor group for surface modification of solid polyvinyl alcohol (PVA); the surfaces of PVA microparticles, films, and nanofibers were chemically modified with boronic acid-appended fluorescent dyes through boronate esterification using a simple soaking technique in a short time under ambient conditions.

Crystal polymorphism in polydiacetylene-embedded electrospun polyvinylidene fluoride nanofibers

In this study, polydiacetylene (PDA) is embedded in electrospun polyvinylidene fluoride (PVDF) nanofibers for the preparation of mats with dual colorimetric and piezoelectric responses. The diacetylene monomers are self-assembled during the electrospinning process. The PDA-embedded PVDF nanofibers in the blue phase are obtained via photo-polymerization upon UV-light irradiation. The colorimetric transition of the nanofibers is studied as a function of temperature using a spectrophotometer. The morphology and crystal polymorphism of the nanofibers are investigated. The results show that the addition of PDA increases the diameter of the nanofibers due to the increase in the electrospinning solution viscosity. The results of Fourier transform infrared and wide angle X-ray diffraction demonstrate that PDA has the effect of inhibiting the growth of non-polar α-phase crystals, while promoting the growth of the polar β-phase. However, the red phase of PDA-embedded PVDF exhibits a lower intensity of the β-phase in comparison to that of the blue phase. In fact, the blue-to-red color transition of the PDA-embedded electrospun PVDF nanofibers is accompanied by the variation of piezoelectric signaling caused by variations in the β-phase. This phenomenon creates great potential in commercial detection sensors in addition to their colorimetric detection properties.

Poly(ethylene glycol) and Cyclodextrin-Grafted Chitosan: From Methodologies to Preparation and Potential Biotechnological Applications

Chitosan, a polyaminosaccharide obtained by alkaline deacetylation of chitin, possesses useful properties including biodegradability, biocompatibility, low toxicity, and good miscibility with other polymers. It is extensively used in many applications in biology, medicine, agriculture, environmental protection, and the food and pharmaceutical industries. The amino and hydroxyl groups present in the chitosan backbone provide positions for modifications that are influenced by factors such as the molecular weight, viscosity, and type of chitosan, as well as the reaction conditions. The modification of chitosan by chemical methods is of interest because the basic chitosan skeleton is not modified and the process results in new or improved properties of the material. Among the chitosan derivatives, cyclodextrin-grafted chitosan and poly(ethylene glycol)-grafted chitosan are excellent candidates for a range of biomedical, environmental decontamination, and industrial purposes. This work discusses modifications including chitosan with attached cyclodextrin and poly(ethylene glycol), and the main applications of these chitosan derivatives in the biomedical field.

Utilization of chromic polydiacetylene assemblies as a platform to probe specific binding between drug and RNA

Recognition of nucleic acids remains an important endeavor in biology. Nucleic acids adopt shapes ranging from A-form (RNA and GC rich DNA) to B-form (AT rich DNA). We show, in this contribution, shape-specific recognition of A-U rich RNA duplex by a neomycin (Neo)-polydiacetylene (PDA) complex. PDA assemblies are fabricated by using a well-known diacetylene (DA) monomer, 10,12-pentacosadiynoic acid (PCDA). The response of poly(PCDA) assemblies is generated by mixing with a modified neomycin-PCDA monomer (Neo-PCDA). The functionalization by neomycin moiety provides specific binding with homopolyribonucleotide poly (rA) - poly (rU) stimulus. Various types of alcohols are utilized as additives to enhance the sensitivity of poly(PCDA)/Neo-PCDA assemblies. A change of absorption spectra is clearly observed when a relatively low concentration of poly (rA)-poly (rU) is added into the system. Furthermore, poly(PCDA)/Neo-PCDA shows a clear specificity for poly (rA)-poly (rU) over the corresponding DNA duplex. The variation of linker between neomycin moiety and conjugated PDA backbone is found to significantly affect its sensitivity. We also investigate other parameters including the concentration of Neo-PCDA and the DA monomer structure. Our results provide here preliminary data for an alternative approach to improve the sensitivity of PDA utilized in biosensing and diagnostic applications.

Architectural evolution of phase domains in shape memory polyurethanes by dissipative particle dynamics simulations

The MDI phase in SMPUs develops a framework with netpoints evolving from spheres, to linked-spheres, linked-cylinders, and then to linked-bi-crossing-cylinders.

CO2-responsive polymeric materials: synthesis, self-assembly, and functional applications

CO2 is an ideal trigger for switchable or stimuli-responsive materials because it is benign, inexpensive, green, abundant, and does not accumulate in the system. Many different CO2-responsive materials including polymers, latexes, solvents, solutes, gels, surfactants, and catalysts have been prepared. This review focuses on the preparation, self-assembly, and functional applications of CO2-responsive polymers. Detailed discussion is provided on the synthesis of CO2-responsive polymers, in particular using reversible deactivation radical polymerization (RDRP), formerly known as controlled/living radical polymerization (CLRP), a powerful technique for the preparation of well-defined (co)polymers with precise control over molecular weight distribution, chain-end functional groups, and polymer architectural design. Self-assembly in aqueous dispersed media is highlighted as well as emerging potential applications.

A 3D networked polydiacetylene sensor for enhanced sensitivity

Immobilization of polydiacetylene (PDA) vesicles on the surface of the modified carbon nanotube (CNT)-networked pillared structures afforded a 3D networked sensor system. A more than three order increase in the sensitivity was observed with the 3D networked sensor matrix in comparison with a conventional 2D PDA sensor system.

Enzymatic electrochemical biosensor for urea with a polyaniline grafted conducting hydrogel composite modified electrode

A new conducting polymer hydrogel (CPH) comprising polyaniline grafted polyvinyl alcohol–polyacrylamide ensured high enzyme loading and urea sensitivity.

Doxorubicin-loaded biodegradable self-assembly zein nanoparticle and its anti-cancer effect: Preparation, in vitro evaluation, and cellular uptake

Cancer is one top leading cause of the deaths worldwide. Various anticancer drugs, which can effectively kill cancer cells, have been developed in the last decade. However, the problem is still about the low therapeutic index of the drugs, which means that the effective dose of drugs will cause cytotoxicity to normal cells. A strategy based on drug nano-encapsulation is applied to achieve an effective anti-cancer therapy. In this study, we use zein, which is an amphiphilic protein, to make the anti-cancer drug nano-encapsulation. Doxorubicin (DOX), a popular anti-cancer drug, is selected as the core drug. The results show that DOX could be successfully encapsulated into zein to form spherical nanoparticles. The encapsulation efficiency and loading efficiency could reach as high as 90.06% and 15.01 mg/g, respectively. The cumulative release result showed a desired pH-responsible release behavior: DOX could be released faster in acidic buffer solutions (pH 5.0 and 6.5) than neutral one (pH 7.4). The effects of the nano-encapsulation on the anti-proliferation of HeLa cells were also examined. It indicated that, compared with free DOX, the DOX-loaded zein nanoparticles (DOX-zein-NPs) had a better effect on cancer cell killing at low DOX concentrations. We also investigated the cellular uptake of DOX-zein-NPs using confocal laser scanning microscopy (CLSM), flow cytometry, and transmission electron microscopy (TEM). And the endocytosis mechanism of DOX-zein-NPs entering into HeLa cells was studied using various endocytosis pathway inhibitors.

A polymerizable supramolecular approach for the fabrication of patterned magnetic nanoparticles

A straightforward method for the preparation of patterned magnetite nanoparticles (MNPs) was developed. The polymerizable supramolecular approach afforded finely patterned MNPs on a solid substrate after a sequential UV-irradiation-wet etching-calcination process with an MNP-embedded diacetylene film.