Synthesis and aggregation behavior of N-succinyl-o-carboxymethylchitosan in aqueous solutions

Bis-substituted amino acid functionalized chitosan aerogels: High uranium adsorption capacity and antibacterial properties

Based on the goal of "carbon neutralization and carbon peaking", it is still challenging to develop a high adsorption performance and environmentally friendly material for uranium extraction. We proposed a new idea of "Three-Dimensional Environmental-Friendly". A series of amino acid bis-substituted chitosan aerogels (C-1, C-2, C-3, C-4 and C-5) were prepared by ice template method and selective substitution reaction in water environment. Among them, C-3 adsorbent has the antibacterial properties of gram-positive bacteria, gram-negative bacteria and marine bacteria, which is more suitable for uranium adsorption in complex environments. Also, C-3 adsorbent solves the shortcomings of poor adsorption property and easy to cause secondary pollution during modification of traditional chitosan materials. The selectivity and adsorption capacity of uranium are further improved by the unique functional groups of serine residues. At pH = 7, the maximum adsorption capacity reaches 606.32 mg/g. In addition, C-3 adsorbent have excellent selectivity and stability. The synergistic effect of coordination, electrostatic interaction and intraparticle diffusion between C-3 adsorbent and uranium may be the key to its high adsorption performance. The high performance of chitosan adsorbent provides a new idea for the design and application of green and efficient uranium adsorption materials.

Effect of Active Site Modification towards Performance Enhancement in Biopolymer κ-Carrageenan Derivatives

This research demonstrates a one-step modification process of biopolymer carrageenan active sites through functional group substitution in κ-carrageenan structures. The modification process improves the electronegative properties of κ-carrageenan derivatives, leading to enhancement of the material's performance. Synthesized succinyl κ-carrageenan with a high degree of substitution provides more active sites for interaction with analytes. The FTIR analysis of succinyl κ-carrageenan showed the presence of new peaks at 1068 cm-1, 1218 cm-1, and 1626 cm-1 that corresponded to the vibrations of C-O and C=O from the carbonyl group. A new peak at 2.86 ppm in 1H NMR represented the methyl proton neighboring with C=O. The appearance of new peaks at 177.05 and 177.15 ppm in 13C NMR proves the substitution of the succinyl group in the κ-carrageenan structure. The elemental analysis was carried out to calculate the degree of substitution with the highest value of 1.78 at 24 h of reaction. The XRD diffractogram of derivatives exhibited a higher degree of crystallinity compared to pristine κ-carrageenan at 23.8% and 9.2%, respectively. Modification of κ-carrageenan with a succinyl group improved its interaction with ions and the conductivity of the salt solution compared to its pristine form. This work has a high potential to be applied in various applications such as sensors, drug delivery, and polymer electrolytes.

Folate receptor targeted, carboxymethyl chitosan functionalized iron oxide nanoparticles: a novel ultradispersed nanoconjugates for bimodal imaging

This article delineates the design and synthesis of a novel, bio-functionalized, magneto-fluorescent multifunctional nanoparticles suitable for cancer-specific targeting, detection and imaging. Biocompatible, hydrophilic, magneto-fluorescent nanoparticles with surface-pendant amine, carboxyl and aldehyde groups were designed using o-carboxymethyl chitosan (OCMC). The free amine groups of OCMC stabilized magnetite nanoparticles on the surface allow for the covalent attachment of a fluorescent dye such as rhodamine isothiocyanate (RITC) with the aim to develop a magneto-fluorescent nanoprobe for optical imaging. In order to impart specific cancer cell targeting properties, folic acid and its aminated derivative was conjugated onto these magneto-fluorescent nanoparticles using different pendant groups (-NH(2), -COOH, -CHO). These newly synthesized iron-oxide folate nanoconjugates (FA-RITC-OCMC-SPIONs) showed excellent dispersibility, biocompatibility and good hydrodynamic sizes under physiological conditions which were extensively studied by a variety of complementary techniques. The cellular internalization efficacy of these folate-targeted and its non-targeted counterparts were studied using a folate-overexpressed (HeLa) and a normal (L929 fibroblast) cells by fluorescence microscopy and magnetically activated cell sorting (MACS). Cell-uptake behaviors of nanoparticles clearly demonstrate that cancer cells over-expressing the human folate receptor internalized a higher level of these nanoparticle-folate conjugates than normal cells. These folate targeted nanoparticles possess specific magnetic properties in the presence of an external magnetic field and the potential of these nanoconjugates as T(2)-weighted negative contrast MR imaging agent were evaluated in folate-overexpressed HeLa and normal L929 fibroblast cells.

Polysaccharide surface modified Fe3O4 nanoparticles for camptothecin loading and release

Fe(3)O(4) nanoparticles were stabilized using different functional polysaccharides, such as chitosan (CS), O-carboxymethylchitosan (OCMCS) and (N-succinyl-O-carboxymethylchitosan (NSOCMCS) to improve their bioactivity. The release profile and the in vitro cancer cell inhibition activity of camptothecin (CPT) loaded polysaccharide modified Fe(3)O(4) nanoparticles were systematically studies. The particle size and size distribution of CPT-loaded polysaccharide modified Fe(3)O(4) nanoparticles were found to be strongly dependent on polysaccharide character. Such polysaccharide character could also affect CPT adsorption efficiency, CPT release behavior and bovine serum albumin (BSA) unspecific binding capacity. After 24 h incubation of 7721 cancer cells with CPT-loaded polysaccharide modified Fe(3)O(4) nanoparticles, significant changes in cell morphology could be discernible from phase contrast microscopy. Cytotoxicity assay showed these polysaccharide modified Fe(3)O(4) nanoparticles did not exhibit noteworthy cytotoxicity against 7721, however, the in vitro inhibition rate of CPT-loaded polysaccharide modified Fe(3)O(4) nanoparticles against 7721 liver cancer cell increased significantly in comparison with that of CPT-free drug.