Glaucoma is known to be one of the principal causes of vision loss due to elevated intraocular pressure. Currently, latanoprost eye drops is used as first-line treatment for glaucoma; however, it possesses low bioavailability due to rapid precorneal clearance. A novel delivery system with a mucoadhesive property could overcome this problem. Therefore, we attempt to develop a combination of self-assembling latanoprost nanomicelles (Latcel) and a mucoadhesive polymer (N,O-carboxymethyl chitosan: N,O-CMC) to improve the corneal residence time. Latcel was developed using Poloxamer-407 by thin film hydration method, followed by the addition of N,O-CMC using simple solvation to obtain Latcel-CMC and characterized using various physicochemical characterization techniques. The particle size of Latcel-CMC was 94.07 ± 2.48 nm and a zeta potential of -16.03 ± 0.66 mV, with a sustained release for 24h whereas marketed latanoprost drops released 90 % of the drug within 1h. In vitro cytotoxicity studies, HET-CAM, and in vivo Draize test showed the biocompatibility of Latcel-CMC. Cellular uptake studies performed using fluorescein isothiocyanate (FITC) loaded nanomicelles in human corneal epithelial cells indicates the increased cellular uptake as compare to plain FITC solution. In vivo ocular residence time was evaluated in Wistar rats using Indocyanine green (ICG) loaded nanomicelles by an in vivo imaging system (IVIS), indicating Latcel-CMC (8h) has better residence time than plain ICG solution (2h). The Latcel-CMC showed improved corneal residence time and sustained release of latanoprost due to increased mucoadhesion. Thus, the developed N,O-Carboxymethyl chitosan based nanomicelles eye drop could be a better strategy than conventional eye drops for topical delivery of latanoprost to treat glaucoma.

Biodegradable and injectable hydrogels derived from natural polysaccharides have attracted extensive attention in biomedical applications due to their minimal invasiveness and ability to accommodate the irregular wound surfaces. In this work, we report the development of an in-situ-injectable, self-healing, antibacterial, hemostatic, and biocompatible hydrogel derived from the hybrid of N,O-carboxymethyl chitosan (N,O-CMC) and oxidized chondroitin sulfate (OCS), which did not require any chemical crosslinking. The N,O-CMC/OCS hydrogel could be readily produced under physiological conditions by varying the N,O-CMC-to-OCS ratio, relying on the Schiff base reaction between the -NH- functional groups of N,O-CMC and the -CHO functional groups of OCS. The results showed that the N,O-CMC2/OCS1 hydrogel had relatively long gelation time (133 s) and stable performances. The viability of NIH/3T3 cells and endothelial cells cultured with the N,O-CMC2/OCS1 hydrogel extract was roughly 85%, which demonstrated its low cell toxicity. Besides, the N,O-CMC2/OCS1 hydrogel revealed excellent antibacterial properties due to the inherent antibacterial ability of N,O-CMC. Importantly, the hydrogel tightly adhered to the biological tissue and demonstrated excellent in vivo hemostatic performance. Our work describing an injectable, self-healing, antibacterial, and hemostatic hydrogel derived from polysaccharides will likely hold good potential in serving as an enabling wound dressing material.

Electrical discharge plasma in a liquid phase can generate reactive species, e.g. hydroxyl radical, leading to rapid reactions including degradation of biopolymers. In this study, the effect of plasma treatment time on physical properties and cytotoxicity against cancer cells of N,O-carboxymethyl chitosan-stabilized gold nanoparticles (CMC-AuNPs) was investigated. AuNPs were synthesized by chemical reduction of HAuCl4 in 2 % CMC solution to obtain CMC-AuNPs, before being subjected to the plasma treatment. Results showed that the plasma treatment not only led to the reduction of hydrodynamic diameters of CMC-AuNPs from 400 nm to less than 100 nm by the plasma-induced degradation of CMC but also provided the narrow size distribution of AuNPs having diameters in the range of 2-50 nm, that were existing in CMC-AuNPs. In addition, the plasma-treated CMC-AuNPs could significantly reduce the percentage of cell viability of breast cancer cells by approximately 80 % compared to the original CMC and CMC-AuNPs.

In this study, pH-sensitive blended polymeric beads were prepared by ionic gelation of mixed alginate and N,O-carboxymethyl chitosan (NOCC) solutions in aqueous media containing calcium chloride. To prepare drug-loaded beads, sulfasalazine (SA) as a model drug was added to the initial aqueous polymer solution. These beads were characterized and evaluated in vitro as potential carriers for colon-specific drug delivery. A 32 full factorial experimental design was employed to evaluate the effect of polymer and CaCl2 concentrations on swelling and drug release behavior of the beads in simulated gastrointestinal tract fluid. It was found that the rate of swelling and drug release decreased significantly with increasing polymer and CaCl2 concentrations, but polymer concentration was more effective than CaCl2 concentration. The beads prepared using 4.5% polymer concentration and 4% CaCl2 concentration retained approximately 60% of the loaded drug before approaching the simulated colonic fluid. Based on the results, the alginate-NOCC beads prepared with high polymer concentration could be potentially suitable polymeric carriers for colon-specific delivery of SA.

Oil spills are the significant sources of hydrocarbons entering in the receiving aquatic environment. An efficient method to remove hydrocarbons from water resources is adsorption. In this study, water soluble N,O-carboxymethyl chitosan (NO-CS) was synthesized by carboxymethylation of chitosan in a hydro-alcoholic medium at 50°C by chloroacetic acid. The polymer was characterized through degree of deacetylation, degree of substitution, FTIR and 1H NMR. Effectiveness of NO-CS as an adsorbent was studied as a function of dosage, salinity and pH to destabilize the Marine diesel (Oil-1), Diesel (Oil-2) and Marine-2T oil (Oil-3) into small oil droplets of less than 100μm. Optical microscope was used for studying the size of oil droplets and adsorption effect of the oils on this polymer. The destabilization of marine diesel was the most effective among the studied three oils, which showed excellent adsorption at sea water alkalinity and salinity.

The effects of coacervation acidity, phase separation temperature, ionic strength, and biopolymer ratio on the viscoelasticity of the N,O-carboxymethyl chitosan (NOCC) - gum Arabic (GA) coacervate were investigated by using coacervate yield as the indicator of electrostatic interaction strength. The strongest interaction between NOCC and GA occurred at pH 3.0, whereas the highest modulus values were found in the coacervate separated at pH 6.0. The coacervate yield did not vary with phase separation temperature in the range 4-55°C, but the coacervate viscoelasticity declined as the temperature increased from 25°C to 45°C and then peaked at 55°C. The presence of NaCl weakened the electrostatic interaction between the two polyelectrolytes, but no dose-dependent reduction in viscoelasticity was observed for their coacervates. Besides, the highest electrostatic interaction strength and coacervate viscoelasticity were recorded at different GA to NOCC ratios. It is proposed that the strength of electrostatic interaction is not the only parameter that determines the viscoelasticity of the NOCC - GA coacervate.

The pH-sensitive hydrogels composed of sodium caseinate (SC) and N,O-carboxymethyl chitosan (NOCC) were prepared and a new method to characterize the gelation process was presented in this work. Reological tests suggested that RSC/NOCC=3/7 (the weight ratio of SC and NOCC) was the best ratio of hydrogel. The well-developed three-dimensional network structures in the hydrogel were confirmed by AFM. Two structural parameters, tIS and tCS, denoted as the initial and critical structure formation time, respectively, were used to provide an exact determination of the start of structure formation and description of gelation process. The gelation process strongly depended on temperature changes, a high temperature resulted in an early start of gelation. The non-kinetic model suggested the higher activation energy in the higher temperatures was disadvantageous to structure formation, and vice versa. Due to the smart gel reported here was very stable at room temperature, we believed that the gel is required for applications in drug delivery or could be exploited in the development of potential application as molecular switches in the future.

In previous studies, N,O-carboxymethyl chitosan has been shown to decrease the incidence and intensity of abdominal adhesions. In the present study, adhesions were induced in 220 rabbits using a double uterine horn model. Rabbits were randomized to receive an operation only or an operation+medical chitosan intraperitoneally. Twenty-two rabbits from each group were euthanized at one of five different times (Day 3, 7, 14, 28, or 42), and adhesion formation was given gross and histopathological scores. Reductions were observed in adhesion extent (P=0.0337) and tenacity (P=0.0271) as well as inflammation (P<0.0001) on Day 3 when medical chitosan was applied. Prior to Day 14, fibrosis was less obvious in the medical chitosan group (P< 0.0005). The tenacity scores were significantly lower in the medical chitosan group following Day 14 (P<.05), while the type scores were lower in the medical chitosan group following Day 28 (P<.03). Thus, medical chitosan decreased both the gross and the histopathological scores of the induced adhesions.

N,O-Carboxymethyl chitosan (NOCC) can prevent postsurgical adhesion formation. Here, we described the preparation of a novel silkworm pupa NOCC and its effects on the prevention of postoperative adhesion in a rat cecal abrasion model. The degree of deacetylation (DDA) of silkworm pupa chitosan was only 49.87 ± 0.86%; regardless, it was used as the raw material to construct the novel silkworm pupa NOCC, which had a weaker crystallinity than the NOCC standard. Sixty male Sprague-Dawley rats were divided into three groups and treated as follows: 0.9% normal saline solution as a negative control, medical anti-adhesion gel as a positive control and the silkworm pupa NOCC anti-adhesion solution. Two and three weeks after surgery, the animals were killed and the adhesion formation was scored. The silkworm pupa NOCC solution significantly decreased the levels of WBC, TNF-α, IL-1β, IL-2, IL-6 and IL-8 but had no effect on IL-4. Additionally, a lower level of TGF-β1 expression was found in the silkworm pupa NOCC group, and significantly less collagen (P<0.01) and fewer inflammatory cells and fibroblasts were detected in the animals of this group. These results suggested that the novel NOCC from silkworm pupa using the method described here have potential applications in the prevention of postoperative intestinal adhesion.

Chitosan (CS) and its carboxymethyl derivatives are smart biopolymers that are non-toxic, biocompatible and biodegradable, and, hence, suitable for various biomedical applications, such as drug delivery, gene therapy and tissue engineering. Curcumin is a major chemotherapeutic agent with antioxidant, anti-inflammatory, anti-proliferative, anticancer and antimicrobial effects. However, the potential of curcumin as a chemotherapeutic agent is limited by its hydrophobicity and poor bioavailability. In this work, we developed a nanoformulation of curcumin in a carboxymethyl chitosan (CMC) derivative, N,O-carboxymethyl chitosan (N,O-CMC). The curcumin-loaded N,O-CMC (curcumin-N,O-CMC) nanoparticles were characterized using DLS, AFM, SEM, FT-IR and XRD. DLS studies revealed nanoparticles with a mean diameter of 150 ± 30 nm. AFM and SEM confirmed that the particles have a spherical morphology within the size range of 150 ± 30 nm. Curcumin was entrapped with in N,O-CMC nanopartcles with an efficiency of 80%. The in vitro drug-release profile was studied at different pH (7.4 and 4.5) at 37°C for different incubation periods with and without lysozyme. Cytotoxicity studies using MTT assay indicated that curcumin-N,O-CMC nanoparticles showed specific toxicity towards cancer cells and non-toxicity to normal cells. Cellular uptake of curcumin-N,O-CMC nanoparticles was analyzed by fluorescence microscopy and was reconfirmed by flow cytometry. Overall, these results indicate that like previously reported curcumin loaded O-CMC nanoparticles, N,O-CMC will also be an efficient nanocarrier for delivering curcumin to cancer cells.