•Photosensitizer-encapsulated amphiphilic chitosan derivative micelles were prepared.•They exhibited controlled photoactivity.•The photoactivity of Photosan was suppressed in the micelles.•The micelles showed strong phototoxicity against human pancreatic cancer cells.•They could be used as a potential photodynamic therapy in pancreatic cancer.Photosensitizer-encapsulated amphiphilic chitosan derivative (Photosan-DA-Chit) micelles with controlled photoactivity have been prepared using a simple self-assembly method in phosphate-buffered saline (pH 6.2). The fluorescence quantum yield and fluorescence lifetime of the Photosan-DA-Chit micelles were lower than those of free Photosan, which indicated that the micelles were suppressing the photoactivity of Photosan. However, upon incubation with human pancreatic cancer cells (i.e., Panc-1 cells), the Photosan-DA-Chit micelles showed higher fluorescence activity than free Photosan and generated higher levels of reactive oxygen species under laser illumination. The Photosan-DA-Chit micelles therefore exhibited strong phototoxicity, which led to significant levels of apoptosis in the Panc-1 cells. In the absence of light, however, the Photosan-DA-Chit micelles showed no cytotoxicity. These results indicated that they could be used as a potential photodynamic therapy in pancreatic cancer.

Photosensitizer (photosan)-encapsulated micelles were prepared by self-assembly of Photosan with two amphiphilic polysaccharide derivatives, including the cholesteryl conjugated sodium alginate derivative (CSAD) and the deoxycholic acid group conjugated chitosan derivative (DA-Chit). The results of UV-Vis and fluorescence spectroscopy indicated that the hydrogen bonding strength dominated the micelle formation. Methyl viologen was used as a model quencher of photosan. Using the steady-state fluorescence technology, the quenching constants were determined to be 2.05, 1.88 and 0.30 L/mmol for the free photosan, the photosan-CSAD micelle and the photosan-DA-Chit micelle, respectively. This suggested that photosan was protected from quenching of methyl viologen by the polysaccharide micelles. In addition, the protection effect of the photosan-DA-Chit micelle was significantly stronger than that of the photosan-CSAD micelle. The photosan-DA-Chit micelle is thus anticipated for protection of photoactivity of photosan during the blood circulation process in vivo.

The water-soluble chitosan derivative grafted with short amylose chains (Chit-Amy-III) was synthesized through the phosphorylase-catalyzed enzymatic polymerization, following that the chitosan was grafted with maltoheptaose residues by reductive amination. The chemical structures were characterized by FTIR, 1H NMR, Raman, XRD and static light scattering analyses. The results indicated that the amylose chains were conjugated with the chitosan backbone through the reductive Shiff base bonds (–CH–NH–), and the polymerization degree of the grafted amylose chains was about 25. The dispersion stability of single-walled carbon nanotubes (SWNTs) in water was improved through the complexation of Chit-Amy-III derivatives with SWNTs. Raman, XRD and TEM analyses confirmed that the resultant Chit-Amy-SWNTs complex was formed by the wrapping of the Chit-Amy-III derivative around the SWNTs. The results of electrochemical analysis indicated that the Chit-Amy-SWNTs complex modified electrode displayed excellent electron conductivity and electrocatalytic activity on H2O2.

The enzyme-dependent conjugates of indomethacin and amylose (Am–IND) were synthesized at room temperature using N,N′-dicyclohexylcarbodiimide (DCC) as a coupling agent and 4-(N,N′-dimethylamino) pyridine (DMAP) as a catalyst. Their structures were characterized by FTIR and 1H NMR analyses, and the results indicated that the IND residues were conjugated with amylose backbones through ester bonds. For the conjugate with a lower IND content, the better water absorption property was advantageous for enzymes diffusing into the swollen conjugate, resulting in biodegradation of the conjugates and release of IND. In vitro biodegradation evaluation indicated that the Am–IND conjugates were biodegraded in the simulated media of the intestines. In vitro drug release experiments showed that the Am–IND conjugates exhibited a sustained release behavior in the simulated media of the intestines, while IND was hardly released in the simulated gastric fluid. These features provide a great opportunity to use the conjugates as a prodrug for intestinally targeted and controlled release of IND through oral administration. This study may lead to the development of effective methods for utilizing amylose as a new drug delivery carrier.

An acidic tea polysaccharide (ALTPS), isolated from green tea (Camellia sinensis), was characterized as a hyperbranched glycoprotein containing the acidic heteropolysaccharide chains and the protein residues from the results of UV−vis, FTIR, one- and two-dimensional NMR, GC, GC-MS, and amino acid analyses. Solution properties of ALTPS were investigated by static and dynamic light scattering analyses and viscometry. The results indicated that the viscosity behavior of ALTPS exhibited a typical polyelectrolyte effect in distilled water, which may be avoided by adding salts. The low intrinsic viscosity of ALTPS in the solutions (8−15 mL/g) is attributed to its hyperbranched structure. By application of the polymer solution theory, it was revealed that ALTPS was present in a sphere-like conformation in the solutions as a result of the hyperbranched structure. The TEM image further confirmed that ALTPS existed in a spherical conformation in aqueous NaCl solution. Glucose was absorbed by ALTPS, which may be one of blood glucose lowering mechanisms of tea polysaccharides.

Some polysaccharides isolated from natural sources show various important biological activities, such as antitumor, immunomodulatory, and anti-inflammatory effects, which are strongly affected by their chemical structures and chain conformations. This article attempts to review the current development on structural and conformational characterization of some importantly bioactive polysaccharides isolated from natural sources. The chemical structures were analyzed by FTIR, liquid-state NMR (one and two dimensions), solid-sate NMR, Raman spectroscopy, gas chromatography (GC), GC–Mass (GC–MS), and high-performance liquid chromatography (HPLC). The chain conformations of polysaccharides in solutions were investigated using static and dynamic light scattering, viscosity analysis based on the theory of dilute polymer solution, circular dichroism analysis, atomic force microscopy (AFM) including single molecular AFM and AFM-based single-molecule force spectroscopy, fluorescence correlation spectroscopy and NMR spectroscopy.

The self-assembly of amphiphilic cholesteryl-bearing carboxymethylcellulose derivatives (CCMCs) from individual molecules to self-aggregates, in addition to their rheological behaviour in aqueous solution were investigated. The conformations of the individual CCMC individual molecules and self-aggregates, and the microstructures of CCMC self-aggregates were characterized using the static and dynamic light scattering analyses, and the steady fluorescence technology. The results showed that the individual CCMC chains became compact, and aqueous NaCl solution changed from an approximate θ solvent to a bad one when the number of hydrophobic cholesteryl groups increased. The CCMC self-aggregates exhibited as compact spheres. The microstructural characterization indicated that one CCMC self-aggregate consisted of multiple individual CCMC molecules and hydrophobic microdomains, and multiple cholesteryl groups self-associated into one hydrophobic microdomain. The atomic force microscopy images of CCMC self-aggregates in phase mode showed that the multiple interior hydrophobic phase separation regions were surrounded by hydrophilic polysaccharide chains, providing an evidence for multiple hydrophobic microdomains in one self-aggregate. The rheological analysis proved that the CCMC self-aggregates were a microgel, in which the associations of cholesteryl groups provided multiple cross-linking points in the polymer network. The microgel solutions displayed a unique thixotropy and a shear thinning behaviour.

•Chitosan derivatives bearing deoxycholic acid/vitamin B12 residues were synthesized.•Nano-complexes of chitosan derivatives and Astragalus polysaccharides were prepared.•Fluorescence and resonance light scattering spectroscopy confirmed formation of complexes.•The nano-complexes exhibited high permeation through intestinal enterocytes.To improve the small intestinal absorption efficacy of Astragalus polysaccharides (APS) through oral administration, amphiphilic chitosan derivatives conjugated with deoxycholic acid residues in the absence and presence of vitamin B12 residues (DA-Chit and VB12-DA-Chit, respectively) were synthesized and characterized by FTIR and NMR spectroscopy. APS and the amphiphilic chitosan derivatives formed the nano-complexes with positive zeta potentials in the size of 100–150 nm observed using scanning electron microscopy. To investigate the fluorescent properties of APS, a Congo red residue-conjugated APS derivative (CR-APS) was synthesized. Fluorescence spectroscopy and resonance light scattering spectroscopy confirmed the formation of the CR-APS/DA-Chit nano-complex as a result of electrostatic interaction. The APS/DA-Chit and APS/VB12-DA-Chit nano-complexes were not toxic against the human colon adenocarcinoma (Caco-2) cells. The APS/VB12-DA-Chit nano-complex exhibited high permeation through intestinal enterocytes using the Caco-2 cell model, which could be beneficial to small intestinal absorption of humans.