Synthesis of calcium carbonate–chitosan composites via biomimetic processing

The crystal growth of calcium carbonate on a chitosan substrate was achieved using a supersaturated calcium carbonate solution, at different concentrations of polyacrylic acid (PAA) as an additive. Several techniques have been employed to characterize the systems. The pH of the solution as the one of indices was used to monitor the crystallization. In the absence of polyacrylic acid, the pH of the solution changed from 6.00 to 8.50 during the crystallization; meanwhile, sporadic nucleation and crystallization was observed via optical microscopy. By introducing polyacrylic acid to the systems, positively charged protonated nitrogen and negatively charged carboxylate ions were produced by reaction between the amino group in chitosan and the carboxyl group in polyacrylic acid, which were detected by ATR-IR and XPS techniques. These charges induced calcium carbonate nucleation of calcite and vaterite crystals on the chitosan-film surface. The average size of the vaterite phase was about 15 nm, determined by XRD. The pH of the solution changed from 5.80 to 9.25 during the crystallization; moreover, the crystals showed spherical morphology, which consisted of a large number of small particles with a diameter of about 0.2 μm. © 1995 John Wiley & Sons, Inc.     

Synthesis and characterization of new arylamine chitosan derivatives

The synthesis of new chitosan derivatives and their complete characterization by elemental analysis, Fourier transform infrared, thermogravimetric analysis, and cross‐polarity/magic‐angle‐spinning ¹³C NMR is described. A chitosan that was 96.5% deacetylated and had a viscosimetric molecular weight of 131,000 g/mol was prepared. N‐(3,5‐Diethylaminobenzoyl) chitosan with a degree of substitution of 29% and N‐(4‐ethylaminobenzoyl) chitosan with a degree of substitution of 60% were obtained. Such derivatives could be used as metal‐chelating polymers, as flocculants, and in biomedical applications because of the aryl amine moieties in their structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 807–812, 2004     

糠醛改性O-季铵化壳聚糖衍生物的合成及其抗菌性能

在制备水溶性较好的O-季铵化壳聚糖基础上,进一步与糠醛反应制备O-季铵化-N-呋喃亚甲基壳聚糖席夫碱及还原产物O-季铵化-N-呋喃亚甲基壳聚糖衍生物,用FTIR、1H NMR、EA（元素分析）、TG（热重分析）对产物进行表征。测定产物的最低抑菌浓度和抑菌率,并与O-季铵化-N-苯亚甲基壳聚糖席夫碱的抑菌效果进行比较。结果表明,产物对革兰氏阳性菌S.aureus的抗菌效果优于革兰氏阴性菌E. coli,在pH值5.5的条件下抗菌效果优于pH 值7.2。并且O-季铵化-N-呋喃亚甲基壳聚糖的抗菌效果>O-季铵化-N-呋喃亚甲基壳聚糖席夫碱>O-季铵化-N-苯亚甲基壳聚糖席夫碱 > O-季铵化-壳聚糖。研究表明,含呋喃杂环的壳聚糖衍生物的抗菌活性明显优于不含杂环的壳聚糖衍生物。     

Synthesis and characterization of chitosan derivatives carrying galactose residues

A series of water‐soluble chitosan derivatives, carrying galactose residues, were synthesized by using an alternative method in which the galactose groups were introduced into amino groups of the derivatives. First, hydroxyethyl chitosan (HECS) and hydroxypropyl chitosan (HPCS) were synthesized under alkaline conditions by using chitosan and propylene or chitosan and ClCH₂CH₂OH as the starting materials, respectively. Then lactobionic acid was added into the systems so as to form galactosylated HECS (Gal‐HECS) and galactosylated HPCS (Gal‐HPCS) with substitution degrees of 53 and 47%, respectively. Lactosaminated HPCS (Lac‐HPCS) and Lactosaminated HECS (Lac‐HECS) were obtained with substitution degrees of 42 and 38%, respectively, by the reductive amination of the mixtures of lactose and HECS or lactose and HPCS with potassium borohydride present in the reaction. The chemical structures of new chitosan derivatives were characterized by FTIR, ¹H NMR, ¹³C NMR, and elemental analysis. Some physical properties were also analyzed by wide angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). The novel chitosan derivatives carrying galactose residues may be used as additives for hepatic targeting delivery. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2161–2167, 2005     

PEGylated chitosan derivatives: Synthesis, characterizations and pharmaceutical applications

This review sets out to describe and discuss the synthetic approaches and the fields of application of PEGylated chitosan copolymers especially for medical use. The PEGylation of chitosan and chitosan derivatives is able to add new physicochemical properties to the cationic polysaccharide polymers, thereby overcoming some limitations, especially regarding their solubility and their use in drug and gene delivery (DNA and siRNA). All methods of derivatization have been considered and described together with the different methods of characterization of the copolymers. The capacities of PEGylated chitosan to reduce chitosan toxicity, to enhance membrane permeation and to form thermosensitive hydrogels have also been discussed.     

Tailoring porphyrins and chlorins for self-assembly in biomimetic artificial antenna systems

There is much diversity in the way in which photosynthetic organisms harvest sunlight. In chromophore-protein complexes, an exact orientation of pigments by the protein matrix ensures an efficient stepwise energy transfer to the reaction center where charge separation occurs. The charge separation and subsequent electron transfer steps are, however, very similar in all organisms, proving that there must exist a common ancestor. The architectural principle of chromophore-protein complexes is too complicated to be replicated in artificial light-harvesting devices. A simpler principle employs self-assembling chromophores that early green photosynthetic bacteria use in their chlorosomal antenna systems. Efforts in mimicking this self-assembly algorithm with fully synthetic pigments are presented. The fact that, as in the natural system, after self-assembly, concentration quenching is not operating due to the very orderly manner in which the chromophores are positioned lends hope for applications in artificial devices, such as hybrid solar cells.     

Synthesis and self‐assembly study of zwitterionic amphiphilic derivatives of chitosan

New zwitterionic derivatives of chitosan (CH) were synthesized through the Michael addition reaction of 1‐(3‐sulfopropyl)‐2‐vinylpyridine hydroxide (SPP) with primary amines of deacetylated CHs (with weight‐average molecular weights of 46 and 216 kDa) to obtain SPP‐substituted CHs. The hydrophilic derivatives were subsequently modified with 2.1, 4.6, and 9.7% of dodecyl groups [degree of substitution by dodecyl groups (DS_Dod)]. The SPP‐substituted CH derivatives were characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, and gel permeation chromatography. Aqueous solutions of SPP‐substituted CH samples remained clear, independently of the pH (3.0 < pH < 12.0). The self‐association study of the amphiphilic derivatives was performed in aqueous buffered solution at pH 5.0 and 7.4, and the critical aggregation concentration values varied from 5.6 × 10^?3 to 0.02 g/L. The measurements of dynamic light scattering and ζ potentials showed that the self‐assembly behavior was dependent on the pH and DS_Dod. At pH 7.4, the measured ζ potentials were near zero, and colloidal stability was provided by the hydrated zwitterionic shell of the aggregates. Transmission electron microscopy revealed spherelike microsized particles of broad distribution. The amphiphilic SPP‐substituted CH samples were shown to be nontoxic with a 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay performed with HeLa cells. The remarkable water solubility and nontoxicity displayed by the new SPP‐substituted CH derivatives showed promising properties for the design of CH‐based biomaterials and nanoparticles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44176.     

新型壳聚糖季铵盐抗菌剂的合成及其性能

先用两步法合成了无O-甲基化 N,N,N-三甲基壳聚糖季铵盐（TMC）,再通过相转移催化合成了N,N,N-三甲基O-辛基壳聚糖季铵盐（TMOC）,用 FTIR、1H NMR、EA、TG 等方法对产物进行表征,并研究其抗菌性能。结果表明,TMOC在pH值为5.5的抗菌活性优于pH值为7.2的抗菌活性;TMOC对革兰阳性菌S. aureus的抗菌活性比革兰阴性菌E. coli强。在不影响水溶性的前提下,O-烷基化改性能有效提高壳聚糖季铵盐的抗菌活性,并且抗菌活性随着O-烷基化度的提高而提高。研究结果为壳聚糖基抗菌剂的改性和制备提供了依据。     

Amine groups-functionalized alcohol-soluble polyfluorene derivatives: Synthesis, photophysical properties, and self-assembly behaviors

A polyfluorene derivative with primary amine groups on side chains, poly(9,9-bis(6′-aminohexyl)fluorene) (PF-NH₂), was prepared through de-protection of its analogue polymer poly(9,9-bis(6′-butoxylcarbonylaminohexyl)fluorene) (PF-BOC) with hydrochloric acid followed by neutralizing the salt form of poly(6,6′-(9H-fluorene-9,9-diyl)dihexan-1-aminium chloride) (PF-NION). PF-NION had good solubility in methanol, DMSO, and DMF. Scanning electron microscopic images of PF-NH₂ in thin films revealed that intramolecular/intermolecular hydrogen bonding and π-π stacking interactions probably played an important role in the formation of special surface morphologies, which might be beneficial to the molecular ordering and device fabrication. The electroluminescence property of PF-NION was recorded on a simple polymer light-emitting diode (PLED) device configuration of ITO/PEDOT/Polymer/Al. Pure blue electroluminescence is achieved from double-layer PLEDs based on PF-NION as the active material with the CIE of (0.16, 0.08).     

Layer-by-layer self-assembly of collagen and chitosan biomolecules on polyurethane films

Polyurethane (PU) films used in wound dressing applications often have appropriate properties. Still, surface modification is necessary to increase the biocompatibility. In this research, the surface of the PU films was modified with collagen and chitosan biomolecules through layer by layer (LbL) self-assembly process. The PU films were synthesized from castor oil and hexamethylene diisocyanate. Then, they were treated with low-pressure nitrogen plasma to graft with poly(acrylic acid). Before performing the LbL process, the surfaces of the PU films were modified using three different reagents, including (A) NaOH solution, (B) EDC/NHS solution, or (C) hexamethylene diamine. Then, the collagen and chitosan deposited in three and five layers on the surface. The images of FESEM, confocal microscopy, and AFM showed that the best performance of the LbL deposition process was after the surface modification with hexamethylenediamine (HMDA). The MTT assay showed that the presence of these biomolecules had boosted the proliferation of fibroblast cells. Increasing the number of the deposited layer from three to five, decreased the cell viability and antibacterial activity of the films. The obtained results propose the modification with HMDA and the deposition of three layers of collagen and chitosan on the PU films to improve its biocompatibility.     

Synthesis,characterization of biomimetic phosphorylcholine‐bound chitosan derivative and in vitro drug release of their nanoparticles

Novel water‐soluble biomimetic phosphorylcholine (PC)—bound chitosan derivatives (N‐PCCs) with different degree of substitution (DS) via a phosphoramide linkage between glucosamine and PC were synthesized through Atherton‐Todd reaction under the mild conditions, and structurally characterized by ¹H‐NMR, Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), X‐ray diffraction (XRD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Their DS ranged from ～ 16 to ～ 42 mol % based on the ¹H‐NMR spectra. All these N‐PCCs with decreased crystallization showed excellent solubility in the aqueous solutions within a wide pH range (1–12). DSC and TGA results revealed that the thermal stability of N‐PCCs decreased with the increase of DS value. Further, N‐PCCs nanoparticles could be still formed in a spherical shape similar to chitosan nanoparticles by ionic gelation technique, observed by atomic force microscopy (AFM). Dynamic light scattering (DLS) results suggested that the zeta potential value of N‐PCCs nanoparticles decreased with the DS value increasing. Using 5‐fluorouracil (5‐Fu) as a model drug, in vitro drug release studies indicated that N‐PCCs nanoparticles exhibited a similar prolonged release profile as chitosan nanoparticles. The results suggested that N‐PCCs nanoparticles could be used as promising nanocarriers for drug delivery applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Supramolecular self-assembly of biopolymers with carbon nanotubes for biomimetic and bio-inspired sensing and actuation

Biopolymers are important natural multifunctional macromolecules for biomimetic and bio-inspired advanced functional material design. They are not only simple dispersants for carbon nanotube stabilization as they have been found to have specific interactions with carbon nanotubes. Their molecular activity, orientation and crystallization are influenced by the CNTs, which endow their composites with a variety of novel sensing and actuation performances. This review focuses on the progress in supramolecular self-assembly of biopolymers with carbon nanotubes, and their advances in sensing and actuation. To promote the development of advanced biopolymer/CNT functional materials, new electromechanical characteristics of biopolymer/CNT composites are discussed in detail based on the relationship between the microscopic biopolymer structures and the macroscopic composite properties.     

O-磺化/O-季铵化-N,N-双烷基壳聚糖混合单分子膜及自组装囊泡性质

制备了具有良好油溶性的O-磺化-N,N-双十二烷基壳聚糖(HSDLCS)和O-季铵化-N,N-双十二烷基壳聚糖(QADLCS),研究了HSDLCS/QADLCS混合单分子膜和自组装囊泡性质的关系.结果表明,混合单分子膜的崩溃压(46.14mN/m)和最大压缩模量(C_s,max^-1,98.85mN/m)较相应的单组分大;自组装形成球形囊泡的粒径在200～400nm;以维生素B₁₂ 为模型药物制备HSDLCS/QADLCS复合囊泡的载药量为0.1987mg/mg,包封率为38.25%,药物平衡释放率为23.68%.静电作用使得混合单分子膜的凝聚性和抗形变能力更强,复合囊泡药物通透性降低,结构更紧密.单分子膜的C_s,max^-1与其相应载药囊泡药物平衡释放率呈一定的线性关系.     

Preparation and characterization of biomimetic tussah silk fibroin/chitosan composite nanofibers

Tussah silk fibroin (TSF)/chitosan (CS) composite nanofibers were prepared to mimic extracellular matrix by electrospinning with hexafluoroisopropanol (HFIP) as a solvent. The viscosity and conductivity of TSF/CS blend solution were analyzed and the morphology, secondary structure, and thermal property of TSF/CS composite fibers were investigated by SEM, ¹³C CP/MAS-NMR, X-ray diffraction, and DSC Techniques. The electrospinnability of TSF solution was improved significantly by adding 10 wt% CS, and morphology of electrospun TSF nanofibers changed from flat strip to cylindrical. At the same time, the average fiber diameters decreased from 542 to 312 nm, accompanying by an obvious improvement in fiber diameter uniformity. However, when the CS content in blend solution was more than 15 wt%, the diameter of electrospun TSF/CS nanofibers appeared to be polarized which can be attributed to phase separation of the two components in composite nanofibers. Blending 10 wt% CS did not change the conformation of TSF in TSF/CS composite nanofibers, and TSF in composite nanofibers at various composition ratios had mainly taken the α-helix structure. The thermal decomposition temperature of electrospun TSF/CS composite nanofibers decreased with the increase of CS content due to the lower decomposition temperature of CS. To study the cytocompatibility and cell behavior on the TSF/CS nanofibers, human renal mesangial cells were seeded onto electrospun TSF/CS composite nanofibers. Results indicated that the addition of CS promoted cell attachment and spreading on TSF nanofibers significantly, suggesting that electrospun TSF/CS composite nanofibers could be a candidate scaffold for tissue engineering.     

Biologically active amphiphilic derivatives of chitosan

Amphiphilic N-derivatives of chitosan containing C₁₂ alkyl and carboxyl groups were obtained. It was shown that the compounds obtained have fungicidal activity and form intermolecular associates in solutions. __________ Translated from Khimicheskie Volokna, No. 6, pp. 57–58, November–December, 2005.     

壳聚糖衍生物在化妆品中的应用

综述了壳聚糖衍生物:羟基化壳聚糖、羧基化壳聚糖、酰化壳聚糖、壳聚糖季铵盐的制备方法,并介绍了它们在化妆品方面的应用性能.     

Interaction of dyes with chitosan derivatives

The states of water in N-acylated, both aliphatic and aromatic, chitosan gels were investigated by DSC technique. The amounts of two states of water, freezable and nonfreezable water, were found to depend on the chemical and physical structure of the gels. The interaction between these hydrophobic gels and the dyes which have been designed and prepared to carry the ionic, hydrophilic, and hydrophobic nature was determined in detail. The dyes having ? OH, ? N(C₄H₉)₂, and naphthalene nucleus show a remarkable increase of the equilibrium sorption to compare with that of methyl orange. The contribution of the electrostatic, hydrophobic, and hydrogen bonding interaction in the sorption was discussed. The predominant contribution of the hydrophobic interaction in the systems of butyl orange/N-octanoyl chitosan gels has been made clear by means of the temperature dependence of the sorption.     

Synthesis,characterization, and drug‐release behavior of amphiphilic quaternary ammonium chitosan derivatives

A new type of amphiphilic quaternary ammonium chitosan derivative, 2‐N‐carboxymethyl‐6‐O‐diethylaminoethyl chitosan (DEAE–CMC), was synthesized through a two‐step Schiff base reaction process and applied to drug delivery. In the first step, benzaldehyde was used as a protective agent for the incorporation of diethylaminoethyl groups to form the intermediate (6‐O‐diethylaminoethyl chitosan). On the other hand, NaBH₄ was used as a reducing agent to reduce the Schiff base, which was generated by glyoxylic acid, for the further incorporation of carboxymethyl groups to produce DEAE–CMC. The structure, thermal properties, surface morphology, and diameter distribution of the resulting chitosan graft copolymers were characterized by Fourier transform infrared spectroscopy, ¹H‐NMR, thermogravimetric analysis, differential scanning calorimetry, X‐ray powder diffraction, scanning electron microscopy, and laser particle size analysis. Benefiting from the amphiphilic structure, DEAE–CMC was able to be formed into microspheres in aqueous solution with an average diameter of 4.52 ± 1.21 μm. An in vitro evaluation of these microspheres demonstrated their efficient controlled release behavior of a drug. The accumulated release ratio of vitamin B₁₂ loaded DEAE–CMC microspheres were up to 93%, and the duration was up to 15 h. The grafted polymers of DEAE–CMC were found to be blood‐compatible, and no cytotoxic effect was shown in human SiHa cells in an MTT [3‐(4, 5‐dimethyl‐thiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide] cytotoxicity assay. These results indicate that the DEAE–CMC microspheres could be used as safe, promising drug‐delivery systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39890.     

壳聚糖及其衍生物应用研究进展

介绍了壳聚糖的性质及研究历史,综述了壳聚糖及其衍生物在水处理、膜分离、分析化学、纺织工业、冷却水循环系统的阻垢、液晶及生物医用材料等方面的应用研究,并对壳聚糖的应用研究进行了展望。