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Microneedles are a promising micro-scale drug delivery platform that has been under development for over two decades. While 3D printing technology has been applied to fabricate these systems, the challenge of achieving needle sharpness remains. In this study, we present an innovative approach for microneedle fabrication using digital light processing (DLP) 3D printing and smart chitosan biomaterial. For the first time, we used hydroxybutyl methacrylated chitosan (HBCMA), which possesses dual temperature- and photo-sensitive properties, to create microneedles. The DLP approach enabled a quick generation of HBCMA-based microneedles with a high resolution. The microneedles exhibited 4D properties with a change in needle dimensions upon exposure to temperature, which enhances resolution, sharpens needles, and improves mechanical strength. We demonstrated the ability of these microneedles to load, deliver, sustained release small molecular drugs and penetrate soft tissue. Overall, the HBCMA-based microneedles show promising potential in non-dermal drug delivery applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Hybrid-crosslinked systems, which can be formed using heat and visible light, are significant for improving the stability of hydrogels under physiological conditions. However, several challenges for their practical application remain, such as shrinking under culture medium conditions or the neutral pH in the small intestine. Therefore, a multi-sensitive hydrogel with response to external conditions has been designed and prepared, which could be employed as a biopolymer ink formulation for three-dimensional printing in bioengineering applications. When exposed to body temperature and visible light, the N-succinyl hydroxybutyl methacrylated chitosan (NS-HBC-MA) undergoes a sol-gel phase transition. The NS-HBC-MA hydrogel exhibits pH-responsive swelling, effectively preventing shrinkage at a neutral pH. Furthermore, NS-HBC-MA hydrogel demonstrates excellent biocompatibility and biodegradability. This study demonstrates that the NS-HBC-MA hydrogel has significant potential for various applications, including wound healing, delivery systems, and tissue engineering., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Chitosan-based nanoparticles (CNPs) are widely used in drug delivery, cosmetics formulation and food applications. To accelerate the manufacturing of CNPs, the present study develops a workflow to prepare CNPs in a continuous model. Based on machine learning, the workflow precisely predicts size and polymer dispersity index (PDI) value of CNPs, which impacts on the colloidal stability and applications. Multi-inlet vortex mixer (MIVM) device was fabricated by 3D printing as the reactor. Peristaltic pump was applied to deliver the reaction streams into the MIVM device and produce CNPs by flash nanoprecipitation (FNP) in a continuous way. The developed MIVM device produces CNPs in a controlled manner at a higher output which is promising for upscale applications. Twelve machine learning algorithms were employed to investigate the potential relationship between the reaction independent variables and hydrodynamic characteristics of CNPs. Random Forest, Decision Tree, Extra Tree and Bagging algorithms performed better than other algorithms with the average prediction accuracy around 90 %. The current study demonstrated that supervised machine learning guided FNP using the developed MIVM device is an effective strategy for accurate and intelligent production of CNPs and other similar nanoparticles., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The purity of soy lecithin exerts significant impact on nanoliposome (NL) properties for food applications. In this study, three soy lecithin of different purity were used to prepare NL. LC-MS analysis confirmed soy lecithin of relatively low purify (50% and 70%) contains multiple natural phospholipids. NL produced by soy lecithin of middle purity (70%) is smaller and more stable than other counterparts. Ultimately, soy lecithin of 70% purity was selected to develop NL encapsulated crocetin (CR) as model payload and further coated by chitosan (CS). The structure characteristic, physicochemical properties, antioxidant activity and anti-inflammatory activity of crocetin nanoliposome (CR-NL) and chitosan coated crocetin nanoliposome (CS-CR-NL) were evaluated. NL encapsulation and CS coating significantly improve antioxidant and anti-inflammatory ability of CR, and prolong storage period of CR (p < 0.05). For food applications, soy lecithin of middle purity (70%) is cheaper and more appropriate than soy lecithin of high purity., (Copyright © 2022. Published by Elsevier Ltd.)

Oral administration of insulin faces multiple biological challenges, such as varied digestive environments, mucin exclusion, and low epithelial cells' absorption. In the present study, a hyaluronic acid (HA)-coated chitosan (CS) nanoparticle (HCP) delivery system is fabricated for insulin oral delivery. It is hypothesized that the developed nanoparticles will protect insulin from digestive degradation, promote intestinal epithelial cell absorption, and exert strong in vivo hyperglycemic ability. Nanoparticles formulated by CS and sodium tripolyphosphate (TPP) are optimized to form the core nanoparticles (CNPs). HA is further applied to coat CNP (HCP) to improve stability, reduce enzymatic degradation, and promote absorption of insulin. HCP promotes insulin uptake by Caco-2 cells, absorbs less mucin, and improves intestinal absorption. Moreover, an in vivo test demonstrates that oral administration of insulin-loaded HCP exerts strong and continuous hyperthermia effect (with a pharmacological availability (PA) of 13.8%). In summary, HCP is a promising delivery platform for insulin oral administration in terms of protecting insulin during digestion, facilitating its absorption and ultimately promoting its oral bioavailability., (© 2022 Wiley-VCH GmbH.)

Effective delivery system for oral insulin administration is a promising way for diabetes therapy. Herein, we prepared alginate microbeads containing chitosan nanoparticles (CNP) for controlled release of insulin. CNP was developed by reaction between tripolyphosphate (TPP) and chitosan. The ratio of TPP to chitosan was optimized aiming with smaller and more unified distributed CNP. TEM and DLS analysis confirmed that CNP has size around 150 nm with low PDI value and strong surface charge. Encapsulate ability for bovine serum albumin, working as model protein, was 11.45%, and the encapsulate efficiency was 23.70%. To modify the release profile of protein suitable for oral insulin delivery, sodium alginate was applied to coat on the surface of CNP by electrostatic interaction. After that, CaCl 2 was added to reinforce the alginate coating layer. FTIR analysis confirmed the interaction of alginate with chitosan and reaction with calcium ion. After reaction with Ca 2+ ion, size measurement revealed that CNP was incorporated into alginate microbeads with mean diameter about 3.197 μm. Alginate microbeads presented irregular shape with small particles inside as revealed by optical microscope. Meanwhile, the release test demonstrated that protein release was pH-dependent. Acidic pH value retards protein release and neutral pH value promotes protein release. At last, insulin-loaded alginate microbeads were administrated to hyperglycemia model mice and blood glucose profile was monitored afterward. Insulin-loaded microbeads significantly lowered blood glucose level compared with mice treated with alginate microbeads without insulin. It is noted that insulin-loaded alginate microbeads could lower blood glucose level in much prolonged period of 96 h, indicating that insulin was released in controlled manner.

Nanostructured lipid carriers (NLCs) and chitosan-coated NLCs (CH-NLCs) were prepared by a combined double emulsion and melt dispersion method. The physicochemical properties of them were investigated to determine the optimum conditions. At 3% emulsifier concentration, the NLCs showed about 191.0 ± 4.1 nm mean particle size and low polydispersity index value compared to those observed under other conditions. The encapsulation efficiency of CH-NLCs was 83.9% which was about 10% higher than that of NLCs. In vitro release test showed that low release amount of iron from the NLCs (11%) and CH-NLCs (5%) in simulated gastric condition within 3 h, whereas the iron release amounts of the NLCs and CH-NLCs were high (over 77%) in simulated intestinal condition because both NLCs and CH-NLCs were totally destructed in the intestinal condition after 3 h. In the thiobarbituric acid test, the absorbance of milk-fortified NLC and CH-NLCs was lower than that of original milk. Based on these results, CH-NLCs showed great potential for iron fortification in milk., (© 2017 Institute of Food Technologists®.)

To develop more effective anticancer mucoadhesive drug delivery system for the treatment of colorectal cancer, chitosan based nanogels (NGs) were prepared by electrostatic interaction between chitosan (CS) and carboxymethyl-chitosan (CMCS). By respectively using tripolyphosphate (TPP) and CaCl2 as ionic crosslinker, two well-characterized doxorubicin hydrochloride (DOX) loaded NGs with opposite zeta potential (DOX:CS/CMCS/TPP NGs, -32.6±1.1 mV and DOX:CS/CMCS/Ca2+ NGs, +31.8±0.9 mV) were obtained. Compared with DOX:CS/CMCS/TPP NGs, DOX:CS/CMCS/Ca2+ NGs were taken up to a greater extent by colorectal cancer cells, resulting in greater reduction in percentage of cell viability. Owing to high binding capability to mucin and inhibited paracellular transport by colon, DOX:CS/CMCS/Ca2+ NGs exhibited improved mucoadhesion and limited permeability. This is beneficial to prolong the contact time of formulation onto intestinal mucosa and improved local drug concentration. The results provided evidence DOX:CS/CMCS/Ca2+ NGs to be exciting and promising for the treatment of colorectal cancer., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Chitosan-coated curcumin nanoliposomes (CS-Cur-NLs) were fabricated by the ethanol injection method (EIM), and their physicochemical properties were compared with the properties of those fabricated by the dry thin film method (DTFM). The mean size and zeta potential of CS-Cur-NLs gradually increased with CS concentration. The encapsulation efficiency of Cur-NLs prepared by EIM was 54.70%, which was significantly improved compared to that (42.60%) of Cur-NLs prepared by DTFM. Further improvement of encapsulation efficiency was attained (up to 64.93%) by EIM with 0.1% CS coating. The mucoadhesive property of Cur-NLs improved from 33.60 to 56.47% with CS coating. The results indicate that the encapsulated curcumin will show prolonged adsorption in the gastrointestinal tract because of higher mucoadhesion. Thus, EIM can be considered to be effective for food-grade delivery carriers with higher encapsulation efficiency and absence of harmful solvents. EIM-generated CS-Cur-NLs showed higher bioavailability, with enhanced high mucoadhesive property, storage stability, and encapsulation efficiency.

With the aim to establish a novel nanocarrier system with relatively high payload and high photoprotection capacity for photo-labile active compounds, in this work, deltamethrin (photo-labile compound) was encapsulated into corn oil-nanoemulsions (NE) by a hot high pressure homogenization technique followed by coating with chitosan as the first coating layer (CH-NE) and lignosulfonate as the second coating layer to form a double-layer coated NE (L-CH-NE). The optimal conditions for preparation of NE, chitosan coating and lignosulfonate coating were investigated. The results indicate that polymer coating and the number of coating layers significantly affected the release profile and photoprotection capacity of nanocarriers. In particular, after coating, the release rate became slower and photoprotection capacity became higher. Moreover, in the case of L-CH-NE after 24h of UV exposure in direct photolysis and 2.5h of UV exposure in indirect photolysis, the non-degraded amount of deltamethrin was approximately 4.5 times and 2.1 times, respectively, higher than that of the free-from deltamethrin. In the future, this novel nanocarrier system will show great potential and be widely applied to many fields related to protection of photo-labile compounds against photo-degradation., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Oleoyl-carboxymethyl-chitosan (OCMCS) was synthesized and were soluble at neutral pH. The critical micelle concentration (CMC) of OCMCS in deionized water was 0.021 mg/ml. OCMCS nanoparticles were successfully prepared via self-assembly with mean diameter of 215.34 nm, zeta potential of 19.26 mV and an almost spherical shape as determined by electron microscopy. The OCMCS nanoparticles showed low erythrocyte membrane-damaging effect. The MTT survival assay indicated no significant cytotoxicity to Caco-2 cells and MEFs cells. The uptake of FITC labeled OCMCS nanoparticles by Caco-2 cells was confirmed via confocal laser scanning microscope (CLSM). In vivo toxicity assays were performed via histopathological evaluation, and no specific anatomical pathological changes or tissue damage was observed in the tissues of carps. The extent of tissue distribution and retention following oral administration of FITC-OCMCS nanoparticles was analyzed for 3 days. After 3 days, the nanoparticles remained detectable in the muscle, heart, kidney, liver, intestine, and spleen. The results showed that 34.32% of the particles were localized in the liver, 18.79% in the kidney, and 17.36% in the heart. The lowest percentage was observed in the muscle. These results implied that OCMCS nanoparticles had great potential to be applied as safe carriers for the oral administration of protein drugs., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Background: In the natural environment, photodegradation is one of the most common degradative processes of pesticides. In order to reduce the photodegradation of pesticides, and so increase their killing activity against target pests, chitosan-coated beeswax solid lipid nanoparticles (CH-BSLNs) were prepared by a combination of hot homogenization and sonication, with deltamethrin as an active ingredient., Results: Under optimal conditions, the highest encapsulation efficiency (95%) and a high payload of deltamethrin (approximately 12.5%) were achieved. In direct photolysis, in the case of CH-BSLNs after UV irradiation for 24 h, 37.3% of deltamethrin remained, as opposed to only 14.6% of the free-form deltamethrin. In addition, in indirect photolysis, in the case of CH-BSLNs after UV irradiation for 2 h in 2% acetone solution, approximately 74.5% of deltamethrin remained, as opposed to only 37.6% of the free-form deltamethrin., Conclusion: CH-BSLNs showed good protection for deltamethrin against photodegradation. This novel nanocarrier may be useful in crop protection as an economical strategy to enhance the effect of pesticides in the field and protect the environment as well., (Copyright © 2012 Society of Chemical Industry.)

Oleoyl-carboxymethy chitosan (OCMCS) nanoparticles based on chitosan with different molecular weights (50, 170 and 820 kDa) were prepared by self-assembled method. The nanoparticles had spherical shape, positive surface charges and the mean diameters were 157.4, 274.1 and 396.7 nm, respectively. FITC-labeled OCMCS nanoparticles were internalized via the intestinal mucosa and observed in liver, spleen, intestine and heart following oral deliverance to carps (Cyprinus carpio). Extracellular products (ECPs) of Aeromonas hydrophila as microbial antigen was efficiently loaded to form OCMCS-ECPs nanoparticles and shown to be sustained release in PBS. Significantly higher (P < 0.05) antigen-specific antibodies were detected in serum after orally immunized with OCMCS-ECPs nanoparticles than that immunized with ECPs alone and non-immunized in control group in carps. These results implied that amphiphilic modified chitosan nanoparticles had great potential to be applied as carriers for the oral administration of protein drugs.

Owing to its high biodegradability, and nontoxicity and antimicrobial properties, chitosan is widely-used as an antimicrobial agent either alone or blended with other natural polymers. To broaden chitosan's antimicrobial applicability, comprehensive knowledge of its activity is necessary. The paper reviews the current trend of investigation on antimicrobial activities of chitosan and its mode of action. Chitosan-mediated inhibition is affected by several factors can be classified into four types as intrinsic, environmental, microorganism and physical state, according to their respective roles. In this review, different physical states are comparatively discussed. Mode of antimicrobial action is discussed in parts of the active compound (chitosan) and the target (microorganisms) collectively and independently in same complex. Finally, the general antimicrobial applications of chitosan and perspectives about future studies in this field are considered., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Chitosan-coated nano-size liposomes as a new carrier with bioactivity were made from phosphatidylcholine (pc) and cholesterol (chol) by direct injection. Liposomes prepared using ethanol as a solvent with pc:chol ratios of 40:60 and 60:40 displayed mall mean diameters (97.4nm and 95.8nm, respectively). Different factors affecting the loading efficiency and payload of Vitamin C for these nano-size liposomes were investigated by high-pressure liquid chromatography. Liposomes prepared with a pc:chol ratio of 60:40 were promising Vitamin C carriers with a maximum loading efficiency about 96.5% and payload about 46.82%. When liposomes were prepared with 100mg initial mass of Vitamin C, maximum loading efficiency was obtained. Furthermore, with an increasing initial mass of Vitamin C, the payload increased. Based on the experimental results, it appears that the chitosan concentration does not affect the loading efficiency and payload of liposomes. Liposomes prepared under the above optimum conditions were stable during 15 weeks storage such that over 85% Vitamin C was protected against oxidation.

A novel chitosan antibacterial dispersion system was prepared by oleoyl-chitosan (OCS) nanoparticles (OCNP). We further investigated the antimicrobial mode of OCNP against Escherichia coli and Staphylococcus aureus using a combination of approaches, including measurement of the effect of lecithin and phosphate groups, the conformation of membrane protein, internalization of fluorescein isothiocyanate (FITC)-labeled OCS nanoparticles (FITC-OCS nanoparticles) observed under fluorescence microscopy and DNA/RNA binding assay. Results of fluorescence experiments indicated that OCNP influenced the structure of bacterial membranes. The lecithin effect showed that OCNP bound to cytoplasmic membrane phospholipids of S. aureus, and phosphate groups played an important role. Fluorescence microscopy observations demonstrated that the way OCNP entered into bacteria varied against strains. The gel-retardation experiment showed that OCNP bound strongly to DNA/RNA and retarded their migration in the gels in a concentration-dependent manner. These results indicate that OCNP exerts its antibacterial activity by damaging the structures of cell membrane and putative binding to extracellular targets such as phosphate groups or intracellular targets such as DNA and RNA.

A new nutraceutical carrier, chitosan-coated nano-size liposome, which is itself bioactive, is made from phosphatidylcholine (pc) and cholesterol by the sonication method. Different factors related to the size of the liposomes such as the ratio of the pc and cholesterol and the time of sonication are investigated. At the 40 : 60 ratios of pc and cholesterol with 12 min sonication, the smallest liposomes, with mean diameter ∼82 nm, were obtained. Incorporation of chemically labile active ingredients into the chitosan-coated liposomes prevented chemical degradation, which is shown for vitamin E (VE). After VE was loaded to the liposomes, the size of chitosan-coated liposomes increased to 144 nm. The loading efficiency and payload of VE were investigated by loading different amounts of VE to the liposomes which were prepared with different ratios of pc and cholesterol. Chitosan-coated nano-coated nano-size liposomes appeared to be promising VE carriers, with highest loading efficiency over 99% and payload over 27%. The stability of VE-loaded liposomes suspension during the 8 weeks storage is over 90% under 4°C.

Oleoylchitosans (O-chitosans), with different molecular masses and degrees of substitution (DS), were synthesized by reacting chitosan with oleoyl chloride. The FT-IR suggested the formation of an amide linkage between amino groups of chitosan and carboxyl groups of oleic acid. The viscosity of O-chitosan sharply increased with the increase of concentration, whereas that of unmodified chitosan rose only slightly. This increase was stronger as the increase of hydrophobicity (DS) and molecular mass of the polymer. The critical aggregation concentration (CAC) of O-chitosans with DS 5, 11, and 27% were 79.43, 31.6, 10 mg/L, respectively, and the CAC of samples with molecular masses of 20, 38, 300, and 1100 kDa were 50.1, 74.93, 125.9, and 630.9 mg/L, respectively. All of the O-chitosans could reduce surface tension slightly. Nanoparticles were prepared using an O/W emulsification method. Mean diameters of the polymeric amphiphilic nanoparticles of O-chitosans with DS 5 and 11% were around 327.4 and 275.3 nm, respectively.

Hexanoyl chitosan was synthesized through a coupling reaction between chitosan and hexanoic anhydride. Proton nuclear magnetic resonance (1HNMR) and fourier-transform infrared (FTIR) spectroscopy studies showed the formation of hexanoyl chitosan. The nanoparticles of hexanoyl chitosan were prepared through ionotropic gelation with tripolyphosphate (TPP) followed by sonication. The hexanoyl chitosan-TPP nanoparticles exhibited uniform spherical shape with smooth surface as observed by atomic force microscopy and transmission electron microscopy. The particle size of nanoparticles was between 54.1 to 724 nm with a mean diameter of 324 nm. At 0.2, 0.4, and 0.6 mg/mL bovine serum albumin initial concentration, the encapsulation efficiency and loading capacity of hexanoyl-chitosan-TPP nanoparticles were 58.2, 44.5, and 28.1%, and 14.1, 23.4, and 30.3%, respectively.

Gamma (gamma)-irradiation is finding increasing use in the sterilization of pharmaceutical products. However, irradiation also might affect the performance of drug delivery systems. In this study, the influence of gamma-irradiation on the characteristics of chitosan microparticles was investigated. The diclofenac sodium was incorporated into chitosan microparticles by spray-drying method. The chitosan microparticles (placebo and drug-loaded) were irradiated at doses of 5, 15, and 25 kGy using a (60)Co source. Later, the microparticles were characterized by Fourier transform infrared (FTIR) spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and atomic force microscopy. In addition, microparticles also were evaluated for their sizes, drug content, swelling, and drug release behavior. Encapsulation efficiency of irradiated and nonirradiated microparticles was essentially the same. Notably, surface roughness (rms) of placebo microparticles decreased significantly after gamma-irradiation when compared with nonirradiated placebo microparticles. FTIR spectroscopy revealed that gamma-irradiation of chitosan microparticles induced neither cross-linking nor formation of new group in the chitosan matrix. EPR spectroscopy results showed that the gamma rays induced only one kind of free radical in the chitosan matrix. Size, crystallinity, and thermal properties of the chitosan microparticles did not change much after gamma-irradiation. gamma-irradiated microparticles, exhibited a slightly higher drug release rate and low swelling capacity than the nonirradiated microparticles.

Trypsin was immobilized on linolenic acid modified chitosan using glutaraldehyde (GA) as cross-linker, which was confirmed by Fourier transform infrared (FTIR) spectra. The chitosan nanoparticles containing trypsin (TR) can be prepared after the sonication of immobilized trypsin. The GA concentration affected both the enzyme activity of the nanoparticle and particle size. Results indicated that the activity of trypsin immobilized onto linolenic acid modified chitosan nanoparticles increased with increasing concentration of GA up to 0.07% (v/v) and then decreased with increasing amount of GA. On the other hand, particle size increased (from 523 to 1372 nm) with the increasing concentration of GA (from 0.03 to 0.1% v/v). The enzyme catalytic characteristics of nanoparticle solution were also studied. The results showed that the kinetic constant value (K(m)) of TR immobilized on nanoparticle (71.9 mg/mL) was higher than that of pure TR (50.2 mg/mL). However, the thermal stability and optimum temperature of TR immobilized on nanoparticles improved, which make it more attractive in the application aspect.

Chitosan was modified by coupling with linolenic acid through the 1-ethyl-3-(3-dimethylaminopropyyl)carbodiimide-mediated reaction. The degree of substitution was measured by 1H NMR, and it was 1.8%, i.e., 1.8 linolenic acids group per 100 anhydroglucose units. The critical aggregation concentration (CAC) of the self-aggregate of hydrophobically modified chitosan was determined by measuring the fluorescence intensity of the pyrene as a fluorescent probe. The CAC value in phosphate-buffered saline (PBS) solution (pH 7.4) was 5 x 10(-2) mg/mL. The average particle size of self-aggregates of hydrophobically modified chitosan in PBS solution (pH 7.4) was 210.8 nm with a unimodal size distribution ranging from 100 to 500 nm. A transmission electron microscopy study showed that the formation of near spherical shape nanoparticles had enough structural integrity. The loading ability of hydrophobically modified chitosan (LA-chitosan) was investigated by using bovine serum albumin (BSA) as a model protein. Self-aggregated nanoparticles exhibited an increased loading capacity (19.85 +/- 0.04 to 37.57 +/- 0.25%) with an increasing concentration of BSA (0.1-0.5 mg/mL).

In this study, different molecular weight CM-chitosans were prepared and the effects on the growth and collagen secretion of normal skin fibroblasts and keloid fibroblasts were investigated in vitro. CM-chitosan promoted the proliferation of the normal skin fibroblast significantly but inhibited the proliferation of keloid fibroblast. The higher CM-chitosan concentration had a higher initial effect and the lower CM-chitosan concentration had a longer affecting time to the normal skin fibroblast. The lower molecular weight CM-chitosan had significant twofold activities. The CM-chitosan could reduce the ratio of type I/III collagen in keloid fibroblast by inhibiting the secretion of collagen type I; and had no effect on the secretion of types I and III collagen in the normal skin fibroblast.

In this paper, l‐lysine (Lys), l‐glutamate (Glu), and l‐glutamine (Gln) grafted‐chitosan (CS) polymers (AA‐g‐CS) are prepared by the one‐pot method using EDC/NHS as coupling agents. The introduction of AA into the backbone structure of CS improves its solubility in the pH range of 6.0–7.0. Moreover, AA‐g‐CS/glycerophosphate hydrogel (AA‐g‐CS/GP hydrogel) prepared by physical cross‐linking has better thermosensitivity and can achieve the sol–gel transition in very short order. AA‐g‐CS/GP hydrogel has a dense three‐dimensional network structure, conducing to the loading of the hydrophobic drugs, and its pore size and pore wall are affected by Lys, Glu, and Gln. Berberine hydrochloride (BBH) is encapsulated within the three‐dimensional mesh of the hydrogel. And the addition of BBH has no significant effect on the structure of AA‐g‐CS/GP hydrogel. The optimal parameters for AA‐g‐CS/GP hydrogel loaded BBH (BBH@AA‐g‐CS/GP hydrogel) are the concentration of AA‐g‐CS is 4.5% and the volume ratio of AA‐g‐CS/GP is 1.4/0.6. It is shown that BBH@Lys‐g‐CS/GP hydrogel, BBH@Glu‐g‐CS/GP hydrogel, and BBH@Gln‐g‐CS/GP hydrogel have better‐sustained release effect. Moreover, the sustained release of BBH@Lys‐g‐CS/GP hydrogel is the best, and the cumulative release rate is about 56% in 24 h. Therefore, AA‐g‐CS/GP thermosensitive hydrogel is expected to be an excellent vehicle for sustained release of drugs. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to improve the biocompatibility of glutaraldehyde (GA) cross‐linked chitosan coated collagen scaffold for cartilage tissue regeneration. In order to prevent the potential toxicity of GA, we treated the designed scaffold with either glutamic acid or glycine. Amino acid treated scaffolds were characterized by scanning electron microscopy (SEM) techniques. Afterward, chondrocyte interaction with the composite scaffold was investigated assessing cell adhesion and proliferation using Hoechst staining and MTT cell proliferation assay, respectively. The SEM analyses of the scaffolds’ surface and cross‐section confirmed the adhesion of amino acids on the surface of the scaffolds. We also observed that scaffolds’ porosity was reduced due to the coverage of the pores by chitosan and amino acids, leading to low porosity. The use of amino acid improved the chondrocyte adhesion and proliferation inside the scaffolds’ pores when cells were cultured onto the chitosan‐coated collagen scaffolds. Overall, our in vitro results suggest the use of amino acid to improve the biocompatibility of natural polymer composite scaffold being crosslinked with glutaraldehyde. Such scaffold has improved mechanical properties; biocompatibility thus may be useful for tissue regeneration such as cartilage. [ABSTRACT FROM AUTHOR]

Abstract: Pyrifluquinazon modifies insect behavior by rapidly stopping feeding so that insects starve to death. In the present study, the effects of two nano types of pyrifluquinazon and a non-nano type of pyrifluquinazon on mortality of the green peach aphid, Myzus persicae, were investigated using three different concentrations (25, 50, and 100ppm). The nano types of pyrifluquinazon were formulated with a different molecular weight and density than that of chitosan (CS 30,000, 0.1% and CS 3000, 0.3%) for stability of unsteady core materials. According to the bioassay and the increased rate of aphids, both types of pyrifluquinazon at all concentrations were effective for controlling M. persicae. The CS 3000 0.3% nano type pyrifluquinazon exhibited a more effective controlled-release feature than that of the other type. The two nano types and the non-nano type pyrifluquinazon were bioassayed against M. persicae, and feeding behaviors were compared using the electrical penetration graph technique. The non-nano type appeared to have the best lethal efficiency at 2days after treatment at 50 and 25ppm according to the non-penetration time; however, both CS 30,000 0.1% and CS 3000 0.3% were effective at 14days after treatment. Furthermore, reaction time slowed from 14 to 30days after treatment in the CS 3000 0.3% treated aphids. As a result, CS 3000 0.3% had more effective controlled release at both concentrations. [Copyright &y& Elsevier]

The feasibility of chitosan or/and clay coatings as an alternative oxygen barrier material to poly(lactic acid) (PLA) film was investigated. The coated films were composed of natural materials based on biodegradable and biocompatible polymers, which exhibit excellent oxygen-barrier properties compared with neat PLA films. Thus, these films can contribute toward effectively reducing environmental pollution. The chitosan/clay nanocomposite solutions were effectively dispersed through the clay using an ultrasonic bath and homogenizer. The barrier and morphology properties of the PLA films were tested by measuring selected film properties such as oxygen transmission rate (OTR), water vapor transmission rate (WVTR), field emission scanning electron microscopy, X-ray diffraction and transmission electron microscope. OTR values measured using the chitosan and chitosan/clay nanocomposite coatings were significantly lower than those measured for neat PLA film. WVTR values measured using chitosan/clay nanocomposite coatings were also lower than those measured for neat PLA film and PLA film coated with chitosan. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Various N-acyl chitosans with propionyl-, hexanoyl-, nonanoyl-, lauroyl-, pentadecanoyl-, and stearoyl-groups were synthesized and self-aggregated N-acyl chitosan nanoparticles (CSNPs) were prepared by sonication. By the modification with N-acyl groups, CSNPs increased their hydrophobic character and changed its structural features to be more suitable as a delivery carrier. The mean diameters of bovine serum albumin (BSA)-loaded N-acyl CSNPs ranged from 138 to 551 nm. Uniform particle size distribution of BSA-loaded N-acyl CSNPs was observed. The protein loading efficiency of N-acyl CSNPs was about 94-95% with lower BSA concentration (0.1 mg/mL) and not significantly different with acyl chain length. With higher BSA concentration (1.0 mg/mL), however, the highest protein loading efficiency was observed with lauroyl and pentadecanoyl CSNPs. The results suggest that lauroyl and pentadecanoyl CSs are interesting candidates for protein delivery system. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

The influence of antimicrobial packaging on the microbial growth in pasteurized milk and orange juice was examined. The liquid foods were located in contact with paperboard coated with nisin and/or chitosan in a binder of vinyl acetate ethylene copolymer at 3, 10 and 20 °C, and were measured for counts of aerobic bacteria and yeasts in the milk and orange juice, respectively. Paperboard coated only with plain binder was used as a control. The effect of antimicrobial packaging on the microbial growth was analysed by using Baranyi''s growth model. The paperboard coated with nisin and/or chitosan significantly improved the microbial stability of milk and orange juice at 3 and 10 °C, but not so noticeably at 20 °C. Of those tested, paperboards that included a combination of nisin and chitosan in the coating gave the highest microbial inhibition, and this was most apparent at 10 °C. The effectiveness of antimicrobial paperboard in suppressing the microbial growth was indicated by low maximum temperatures, extended lag time and reduced specific growth rates. Analysis by Ratkowsky equations showed that foods in contact with antimicrobial paperboards showed higher minimum growth temperatures and greater temperature dependence than did foods in contact with plain paper. [Copyright &y& Elsevier]

Carboxymethyl chitosan (CM-chitosan) was prepared by chemical reaction with monochloroacetic acid under various conditions, and the chemical structure was analyzed by IR and NMR. The water solubility of the CM-chitosans had close relationships to the modifying conditions and the degree of carboxymethylation. The CM-chitosans, prepared at temperatures of 0–10 °C were soluble in water. But the CM-chitosan prepared between 20 and 60 °C were insoluble in the water at near-neutral pH. The water insolubility of CM-chitosans at various pHs varied with the degree of carboxymethylation. The increase in reaction temperature increased the fraction of carboxymethylation and increased the insolubility at lower pHs; the increase of the ratio of water/isopropanol in the reaction solvent decreased the fraction of carboxymethylation and increased the insolubility at higher pHs. [Copyright &y& Elsevier]

In this study, chitosan (Ch)-based films containing clove essential oil (CEO) as an active agent were developed by incorporating halloysite nanotubes (HNTs) to stabilize the oil droplets. The physical, mechanical, and antioxidant properties of the films were investigated toward their application as food packaging materials. The water vapor barrier property of the films improved upon the addition of the CEO as well as HNTs, owing to the hydrophobicity of the CEO and formation of tortuous pathways by the HNTs. Scanning electron micrographs of films without HNTs showed a large number of micropores on the film surface while few pores were observed on the film surface with the HNTs. Further, the incorporation of CEO decreased the elongation of the film, whereas the HNT particles dispersed in the film matrix mitigated this effect. The antioxidant activity of the films with different concentrations of HNT was determined by total phenolic content, 2,2-diphenyl-1-picrylhydrazyl, and reducing power assays. The highest antioxidant activity was achieved for the Ch/CEO film with 15 wt% HNT. In migration studies, the release of CEO from the film was found to be faster in 50% ethanol (simulant for oil-in-water emulsions and alcoholic foods) than in 10% and 95% ethanol, which are stimulants of aqueous and fatty foods, respectively. [ABSTRACT FROM AUTHOR]

Abstract: N-acyl chitosans with various acyl chain lengths were synthesized to improve their hydrophobicity and stability in delivery system. N-acyl chitosan nanoparticles were fabricated by self-aggregation method and vitamin C was loaded into the particles. Particle sizes were ranged from 444nm to 487nm with various acyl chain lengths reduced to particle size 216–288nm with vitamin C loading. Vitamin C in the N-acyl chitosan nanoparticles may cross-link and pull the particle wall resulting in reducing the particle size. N-acyl chitosan nanoparticles were characterized using FTIR, zeta potential, size analyzer, scanning electron microscope. The loading efficiency of vitamin C on N-acyl chitosan nanoparticles ranged 55–67% and increased the loading efficiency of vitamin C too, with N-acyl chain length. Vitamin C in N-acyl chitosan nanoparticles showed the controlled release properties at pH 1.3 and pH 7.4. Release rate of vitamin C load is reduced with increasing the length of acyl side chain. [Copyright &y& Elsevier]

Self-aggregation and micelles of amphiphatic polymers are important functions in application, and their properties are influenced by the parent hydrophilic polymer and the hydrophobic groups. In this paper, deoxycholate-chitosan (DE-chitosan) and carboxymethyl-chitosan (CM-chitosan) were prepared from chitosan (MW, 28kDa; DD, 90%). The effects of acid, pH and ionic concentrations on aggregation behaviors of the polymers in aqueous systems were measured, respectively. The ionic strength was found to enhance the aggregation of DE-chitosan, but had no influence to CM-chitosan and chitosan itself. The modification of hydrophobic groups and hydrophilic groups influenced the rheology properties of both parent chitosan and the derivatives. The assemblage of DE-chitosan in solution can be controlled by an oil/water (methylene chloride/DE-chitosan solution) emulsification process using methylene chloride. The micelles of DE-chitosan formed nano-micelles particles of 200–600nm in diameter which can be used to encapsulate lipid-soluble compounds for drug dispersing and delivery releasing. [Copyright &y& Elsevier]

Abstract: Different molecular weight (MW) chitosans (5.5×104 to 15.5×104 Da) with the same degree of deacetylation (80%±0.29), were obtained by the method of acetic acid hydrolysis. The effect of antimicrobial activities of chitosan and acetic acid against Escherichia coli were investigated. All of the chitosan samples with MW from 5.5×104 to 15.5×104 Da had antimicrobial activities at the concentrations higher than 200ppm. The growth of E. coli was promoted at concentration lower than 200ppm. The antibacterial activity of chitosan had relationship to the MW at the concentration range from 50 to 100ppm. The antibacterial activity of low MW chitosan is higher than that of the high MW samples. But the chitosan sample with the middle MW (9.0×104 Da) could promote the growth of bacteria. In the different stages of cultivation, the earlier chitosan was added the greater effect it did. And the mechanism of antibacterial activity was that E. coli was flocculated. [Copyright &y& Elsevier]

Abstract: The hydrogel nanoparticles can be prepared using linoleic modified chitosan following sonication. The morphology and size distribution of nanoparticles were determined by AFM and photocorrelation spectroscopy, respectively. The effects of environment factors on particle size and adsorption of trypsin (TR) were also analyzed. The LA-chitosan nanoparticles were in the range of 200–600nm with satisfactory structural integrity. The particle size slightly increased with an increase in concentration. In high ionic strength solution the particle size decreased, compared to salt-free solution, on the other hand, the particles size increases as urea concentration increased. The particle size was found to be larger in acidic solution than in neutral and alkaline solution. Environment factors (e.g. pH, concentration of urea or NaCl) can affect TR loading on the nanoparticle. The thermal stability of TR loading on nanoparticles was significantly improved compared to free TR. [Copyright &y& Elsevier]

• CD-g-CS with different DS was synthesized successfully. • Novel hydrogel was developed using CD-g-CS and dual gelling agents GP-SHC. • The sustained drug release effect for BBH was achieved by the prepared hydrogel. • BBH@CD-g-CS/GP-SHC hydrogels had excellent antibacterial activity. In this paper, cyclodextrin-grafted-chitosan (CD-g-CS) with different degrees of substitution (DS) was synthesized successfully by the reaction of O -p-toluenesulfonyl-β-cyclodextrin (TCD) and chitosan (CS), and a novel injectable thermosensitive hydrogel with rapid gelation was developed by physical cross-linking using dual gelling agents of αβ-glycerophosphate-sodium and hydrogen carbonate (GP-SHC). The results of 1H-NMR showed that the DS of CD-g-CS increased with the increase of TCD/CS (w/w). The influence of CD-g-CS with different DS, the concentration of SHC, and the ratio of CD-g-CS/GP-SHC (v/v) on gel time, swelling, drug release, degradation, and antibacterial activity of hydrogels prepared were studied. The results of FTIR indicated that the intermolecular interaction occurred in the hydrogel. And the hydrogel had a three-dimensional porous structure seen from SEM images. Compared with CS/GP hydrogel, the gel time of prepared hydrogel was shorter, which was less than 6 min, and the shortest gel time was 0.5 min. The prepared hydrogels had a good swelling ratio and degradable behavior. Berberine hydrochloride (BBH) was used as a model drug, and the gel showed a sustained drug release profile. In addition, the hydrogel had excellent antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Therefore the BBH@CD-g-CS/GP-SHC hydrogels had great potential in the development of biomedical drug delivery systems and antibacterial materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Nano-emulsion (NE) composed of MCT oil, Tween 80 and lecithin was fabricated by ultrasonication method to encapsulate curcumin. Loading ability and efficiency of curcumin were 0.548 mg/mL and 95.10% respectively which indicated its water dispersibility was increased by 1400 fold. Chitosan with low, middle and high molecular weight (3 kDa, 30 kDa and 190–310 kDa respectively) was applied for coating the prepared NE. After chitosan coating, zeta potential value of NE was changed from negative to positive. At the same time, chitosan coating prevented NE phase separation in ionic strength test and inhibited degradation of curcumin during thermal and UV irradiation treatment. Using pH-stat method, it was found that middle and high molecular weight chitosan coating may interfere with lipolysis of NE during the in vitro digestion which also slightly decreased curcumin bio-accessibility. Therefore, NE coated with chitosan is a promising delivery system to promote the applications of curcumin in functional food and beverage system. [ABSTRACT FROM AUTHOR]

Highlights: [•] High-speed and high-pressure homogenization was used to obtain nano-liposome. [•] Liposome was successfully coated by chitosan and eudragit EPO. [•] Physicochemical properties of liposome were affected by manufacture condition. [•] Storage stability of liposomes was enhanced by the polymer coating. [Copyright &y& Elsevier]

Abstract: Lactobacillus casei ATCC 393 was encapsulated with alginate, chitosan and carboxymethyl chitosan by extrusion method and the product could increase the cell numbers of L. casei to be 108 cfu/g in the dry state after storage at 4°C for 4 weeks. After incubation in simulated gastric (pH 2.0, 2h) and bile juices (1%, 6h), the encapsulated L. casei cell numbers were 7.91 and 7.42logcfu/g, respectively. Results indicated that alginate–chitosan–carboxymethyl chitosan microcapsules could successfully protect L. casei against adverse conditions and this approach might be useful in the delivery of probiotic cultures as a functional food. [Copyright &y& Elsevier]

Abstract: A novel chitosan antibacterial dispersion system was prepared by oleoyl-chitosan (O-chitosan) nanoparticles (OCNP) and the bactericidal activity against Escherichia coli and Staphylococcus aureus was evaluated by the enumeration of viable organisms at different incubation times. We further investigated the antimicrobial mode of OCNP using a combination of approaches, including cell integrity measurements, outer membrane (OM) and inner membrane (IM) permeabilization assays, SDS–PAGE and transmission electron microscopy (TEM). Results showed that when treated with OCNP, release of intracellular components quickly increased for both E. coli and S. aureus. OCNP also rapidly increased the 1-N-phenylnaphthylamine (NPN) uptake and the release of cytoplasmic β-galactosidase via increasing the permeability of OM and IM. Besides, SDS–PAGE indicated the content of cellular soluble proteins decreased significantly in OCNP-treated bacteria. TEM observations demonstrated adsorption behaviors of OCNP on bacteria and extensive cell surface alterations of OCNP-treated bacteria. OCNP has potential value in the determination of antibacterial mechanism of chitosan. [Copyright &y& Elsevier]

Abstract: A novel chitosan antibacterial dispersion system was prepared by oleoyl-chitosan (O-chitosan) nanoparticles (OCNP), and the antibacterial activity against Escherichia coli and Staphylococcus aureus was investigated. Results showed that OCNP could be well distributed in nutrient broth and had strong antibacterial activity. The minimum inhibitory concentrations (MICs) of all OCNP samples ranged from 31.25 to 125mg/l against E. coli. For S. aureus, the MIC of all samples was 125mg/l. OCNP of low chitosan molecular weight (MW) appeared most effective against E. coli. For S. aureus, the effect of chitosan MW on the antibacterial activity of OCNP was not pronounced. E. coli was most susceptible to OCNP of O-chitosan with degrees of substitution (DS) 5%, while no marked difference was found among OCNP of O-chitosan with different DS against S. aureus. OCNP exhibited the most pronounced antibacterial activity at pH 6.0 in the experimental range. The integrity of cell membranes was destroyed when bacterial suspensions were treated with OCNP. [Copyright &y& Elsevier]

Abstract: Whole and sliced fresh mushrooms (Agaricus bisporus) were packaged with PVC wrap or two polyolefins (PD-941 and PD-961) films after coating with CaCl2 and chitosan. Package gas composition, color, weight loss and maturity were measured during storage at 12°C and 80%RH. For PD-961, the highest in-package concentration occurred during the first day of storage regardless of treatments, while wrap and PD-941 showed varying degrees in-package concentration with different processes and coatings. The whiteness of whole mushrooms varied significantly with the type of coating, but not with the type of films. The extent of darkening was greater in coated whole mushrooms than in sliced ones. Weight loss occurred in all packages and varied from 3(g/100g) to about 7(g/100g) after 6 days of storage. Due to a lower permeability, PD-961 packages had the lowest weight loss. The type of packaging films significantly affected the maturity index, where PD-961 most effectively lowered maturity index for both whole and sliced mushrooms, thus extending the shelf-life. The type of coating did not appear to affect maturity index except for the wrap package where chitosan coating markedly lowered the maturity index of sliced mushrooms. [Copyright &y& Elsevier]

Chitosans (20 and 100 cp, 2%) were irradiated in acetic acid solution (2%) with different doses (2–200 kGy) of Co-60 gamma rays to investigate the yields of chitosan oligomers. A rapid decrease of viscosity was observed up to 10 kGy and then the viscosity decrease slowed down gradually with increasing irradiation dose. Brown color developed heavily for irradiation dose over 100 kGy. Yields of chitosan dimer, trimer and tetramer were 3.6, 3.0 and 1.8%, respectively, at a dose of 100 kGy in 100 cp chitosan solution. [Copyright &y& Elsevier]