Preparation and drug release characteristics of the conjugates of mitomycin C with glycol-chitosan and N-succinyl-chitosan

Preparation and characterization of C-phycocyanin peptide grafted N-succinyl chitosan by enzyme method

C‑phycocyanin peptide (CPC) grafted N‑succinyl chitosan (NSC) was prepared via the catalysis of Microbial transglutaminase (MTGase). The single factor experiment displayed that the degree of substitution (DS) of N‑succinyl chitosan‑C‑phycocyanin peptide (NSC‑CPC) depended on the reaction time, the reaction temperature and the reaction pH value. The CS, synthesized NSC and NSC‑CPC were characterized by Fourier transform infrared spectroscopy (FT-IR). NSC‑CPC showed excellent moisture absorption and retention ability. In vitro antioxidant activity assays demonstrated that, with the DS and concentration increasing of NSC‑CPC, the scavenging activity of 1,1‑Diphenyl‑2‑pic‑rylhydrazyl (DPPH) radical and hydroxyl radical increased. The methylthiazol tetrazolium (MTT) essay demonstrated that NSC‑CPC inhibited Hela cells while promoted the proliferation of L929 mouse fibroblasts. In conclusion, these results suggested the potential application of NSC‑CPC in pharmaceutical and biomedical fields.

Synthesis, characterization and antibacterial activity of superparamagnetic nanoparticles modified with glycol chitosan

Iron oxide nanoparticles (IONPs) were synthesized by coprecipitation of iron salts in alkali media followed by coating with glycol chitosan (GC-coated IONPs). Both bare and GC-coated IONPs were subsequently characterized and evaluated for their antibacterial activity. Comparison of Fourier transform infrared spectra and thermogravimetric data of bare and GC-coated IONPs confirmed the presence of GC coating on IONPs. Magnetization curves showed that both bare and GC-coated IONPs are superparamagnetic and have saturation magnetizations of 70.3 and 59.8 emu g-1, respectively. The IONP size was measured as ∼8-9 nm by transmission electron microscopy, and their crystal structure was assigned to magnetite from x-ray diffraction patterns. Both bare and GC-coated IONPs inhibited the growths of Escherichia coli ATCC 8739 and Salmonella enteritidis SE 01 bacteria better than the antibiotics linezolid and cefaclor, as evaluated by the agar dilution assay. GC-coated IONPs showed higher potency against E. coli O157:H7 and Staphylococcus aureus ATCC 10832 than bare IONPs. Given their biocompatibility and antibacterial properties, GC-coated IONPs are a potential nanomaterial for in vivo applications.

Chitosan-Based Particles as Controlled Drug Delivery Systems

Chitosan, a natural-based polymer obtained by alkaline deacetylation of chitin, is nontoxic, biocompatible, and biodegradable. These properties make chitosan a good candidate for conventional and novel drug delivery systems. This article reviews the approaches aimed to associate bioactive molecules to chitosan in the form of colloidal structures and analyzes the evidence of their efficacy in improving the transport of the associated molecule through mucosae and epithelia. Chitosan forms colloidal particles and entraps bioactive molecules through a number of mechanisms, including chemical crosslinking, ionic crosslinking, and ionic complexation. A possible alternative of chitosan by the chemical modification also has been useful for the association of bioactive molecules to polymer and controlling the drug release profile. Because of the high affinity of chitosan for cell membranes, it has been used as a coating agent for liposome formulations. This review also examines the advances in the application of chitosan and its derivatives to nonviral gene delivery and gives an overview of transfection studies that use chitosan as a transfection agent. From the studies reviewed, we concluded that chitosan and its derivatives are promising materials for controlled drug and nonviral gene delivery.

In vitro and in vivo evaluation of microparticulate drug delivery systems composed of macromolecular prodrugs

Macromolecular prodrugs are very useful systems for achieving controlled drug release and drug targeting. In particular, various macromolecule-antitumor drug conjugates enhance the effectiveness and improve the toxic side effects. Also, polymeric micro- and nanoparticles have been actively examined and their in vivo behaviors elucidated, and it has been realized that their particle characteristics are very useful to control drug behavior. Recently, researches based on the combination of the concepts of macromolecular prodrugs and micro- or nanoparticles have been reported, although they are limited. Macromolecular prodrugs enable drugs to be released at a certain controlled release rate based on the features of the macromolecule-drug linkage. Micro- and nanoparticles can control in vivo behavior based on their size, surface charge and surface structure. These merits are expected for systems produced by the combination of each concept. In this review, several micro- or nanoparticles composed of macromolecule-drug conjugates are described for their preparation, in vitro properties and/or in vivo behavior.

Review Paper: Chitosan Derivatives as Promising Materials for Controlled Drug Delivery

Chitosan, a natural based-polymer obtained by alkaline deacetylation of chitin, is nontoxic, biocompatible, and biodegradable. These properties make chitosan a good candidate for the development of conventional and novel drug delivery systems. Chitosan has been found to be used as a support material for gene delivery, cell culture, and tissue engineering. However, practical use of chitosan has been mainly confined to the unmodified forms. For a breakthrough in utilization, especially in the field of controlled drug delivery, graft copolymerization onto chitosan will be a key point, which will introduce desired properties and enlarge the field of the potential applications of chitosan by choosing various types of side chains. Chemical modification of chitosan is useful for the association of bioactive molecules to polymer and controlling the drug release profile. This paper reviews the various methods of preparation of chitosan derivatives intended for controlled drug delivery. From the studies reviewed it is concluded that chitosan derivatives are promising materials for controlled drug and nonviral gene delivery.

Structure, depolymerization, and cytocompatibility evaluation of glycol chitosan

Glycol chitosan, a water soluble chitosan derivative being investigated as a new biomaterial, was fractionated via two different methods. Initial characterization of the glycol chitosan with (1)H NMR spectroscopy illustrated the presence of both secondary and tertiary amine groups, contradictory to its widely accepted structure. Fractionation of glycol chitosan with nitrous acid resulted in a significant reduction in the number average molecular weight, specifically, from 170 to approximately 7 kDa for a pH 3 and below. However, the reaction altered its chemical structure, as the secondary amine groups were converted to N-nitrosamines, which are potentially carcinogenic. An increase in the pH of the reaction limited this formation, but not entirely. Free radical degradation initiated with potassium persulfate was not as effective at reducing the molecular weight as the nitrous acid approach, yielding molecular weights around 12 kDa under the same molar ratio of degrading species, but did retain the structural integrity of the glycol chitosan. Additionally, control of the molecular weight appears feasible with potassium persulfate. When assessed in vitro for cytocompatibility, the polymer exhibited no toxicity on monolayer-cultured chondrocytes, and in fact stimulated cell growth at low concentrations.

Preparation and in vitro properties of N-succinylchitosan- or carboxymethylchitin-mitomycin C conjugate microparticles with specified size

The preparation of cross-linked conjugate microparticles of N-succinyl-chitosan (Suc) or 6-O-carboxymethylchitin (CM) with mitomycin C (MMC), which showed an adequate si-e for liver targeting (0.2-3 microm), was attempted by a combination of water-soluble carbodiimide (EDC) coupling and emulsification technique. As for Suc, microparticles with a diameter less than a few micrometers could be obtained easily, while the preparation of CM microparticles (CM-MPs) of the same diameter was not necessarily easy. First, preparation conditions were compared for CM-MPs, and some conditions gave CM-MPs with a diameter less than a few micrometers. As to CM-MMC conjugate microparticles, the method by addition of EDC after emulsification using CM with low molecular weight (CML) gave more appropriate microparticles with a mean diameter of 0.97microm (CM1-MP-MMC). Suc-MMC conjugate microparticles adequate for liver targeting could be produced by the addition of EDC both before and after emulsification, especially, the conjugate microparticles with a mean diameter of 0.45 microm (Suc-MP-MMC) were derived by the addition of EDC before emulsification. Suc-MP-MMC exhibited a higher drug content than CML-MP-MMC. CML-MP-MMC and Suc-MP-MMC exhibited 50% drug release times of 2.87h and 42.1 h, respectively.