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Purpose: To prepare metformin HCl-loaded alginate (AL) and alginate-chitosan (AL-CS) beads for oral application and to evaluate their in vitro characteristics and in vivo activities. Methods: AL and AL-CS beads were prepared using ionotropic gelation. The beads were evaluated for particle size, surface morphology, drug encapsulation efficiency (EE) and in vitro drug release. The antidiabetic effects of the beads were evaluated in diabetic Sprague Dawley rats. Results: The mean particle sizes of AL and AL-CS beads in wet state ranged from 1714 ± 140 to 1850 ± 103 µm. The EE % of AL and AL-CS beads were 33.58 ± 1.56 and 24.11 ± 1.72, respectively, with sustained in vitro drug release of about 93 to 96 % within 8 days in phosphate buffer (PB). Optimized metformin HCl-loaded AL and AL-CS beads showed significant hypoglycaemic effects in diabetic rats over a prolonged period (about 12 h) after oral administration compared to the pure drug (p < 0.05). Conclusion: Metformin HCl-loaded AL and AL-CS beads for oral application may be useful in prolonging the hypoglycaemic effect of metformin. This is capable of increasing patients' compliance to the medication. [ABSTRACT FROM AUTHOR]

Chitosan nanoparticles (CNPs) were prepared with ionotropic gelation between chitosan and tripolyphosphate for the removal of Congo Red. The production of chitosan nanoparticles and the dye removal process was carried out in one-step. The removal efficiency of Congo Red by encapsulation within chitosan from the aqueous solution and its storage stability are examined at different pH values. The influence of some parameters such as the initial dye concentration, pH value of the dye solution, electrolyte concentration, tripolyphosphate concentration, mixing time and speed on the encapsulation is examined. Congo Red removal efficiency and encapsulation capacity of chitosan nanoparticles were determined as above 98% and 5107 mg Congo Red/g chitosan, respectively. [ABSTRACT FROM AUTHOR]

Lysozyme was integrated into chitosan nanoparticles (CS-NPs) to improve the antibacterial activity. CS-NPs and chitosan-lysozyme nanoparticles (CS-Lys-NPs) were prepared according to the ionic gelation technique and then characterized by average size, zeta potential, polydispersity index (PDI), atomic force microscopy (AFM), fourier transform infrared (FT-IR), small-angle X-ray scattering (SAXS), circular dichroism (CD) and UV–visible spectroscopy. Antibacterial properties were investigated by transmission electron microscopy (TEM) based on observation of the inhibition zone and measurement of the minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) of CS-NPs and CS-Lys-NPs against E. coli and B. subtilis . The CS-NPs had particle sizes of 476.2–548.1 nm, while an increase to ∼488.8 to 613.5 nm was observed upon loading with lysozyme. The results suggested that the integration of lysozyme into CS-NPs enhanced the antibacterial activity against E. coli and B. subtilis , which may show great potential for use in the food industry and other applications in the form of direct addition or incorporation into packaging. [ABSTRACT FROM AUTHOR]

β-Chitosan from the gladius was enzymatically depolymerized and utilized for the synthesis of β-chitosan nanoparticles using sodium tripolyphosphate by ionotropic gelation. The size and zeta potential of β-Chitosan nanoparticles (β-CNP) were determined. The structural features were evaluated by FT-IR and NMR spectral analysis. The morphological characterization, composition and surface topography of β-CNP were explored by SEM, EDAX and AFM techniques. The thermal and crystallographic nature of β-CNP was also studied. The cell viability of HepG2 cells inhibited by β-CNP was detected in a dose-dependent manner. The inhibitory concentration of β-CNP was 30 μg/ml. Various biochemical parameters such as TBARS and lipid hydroperoxides, enzymatic and non-enzymatic antioxidant (SOD, CAT, GPx and GSH) studies proved the anticancer property of β-CNP in HepG2 cells. This study suggests that β-CNP should be a promising drug for treating hepatocellular carcinoma in future. [ABSTRACT FROM AUTHOR]

In recent years, nanoparticles (NPs) based on biopolymers or peptides are gaining popularity for the encapsulation and release of drug molecules, especially for cancer therapy, due to their ability for targeted and controlled release. The use of collagen peptide (CP) for the preparation of chitosan (CN) NPs is especially interesting as it results in NPs that are stable under physiological conditions. In this work, mono-dispersed pH responsive CPCN NPs of about 100 nm were prepared via ionic gelation method by simple and mild co-precipitation of CN and CP. Investigation of NPs with Fourier transform infra-red (FTIR) spectroscopy and dynamic light scattering (DLS) measurements reveals that hydrogen bonding and electrostatic interactions are believed to be major driving forces for NP formation and drug encapsulation, respectively. Scanning electron microscopic (SEM) investigations show that hard and fine CPCN NPs transform to soft and bigger gel like particles as a function of collagen concentration. The unique “polymeric gel” structure of NPs showed high encapsulation efficiency towards doxorubicin hydrochloride (DOX) as well as pH controlled release. Anti-proliferative and cell viability analysis revealed that DOX loaded NPs showed excellent anti-proliferative characteristics against HeLa cells with favorable biocompatibility against normal cells. Such NPs have high potential for use as smart drug delivery carriers in advanced cancer therapy. [ABSTRACT FROM AUTHOR]

Chitosan-based thermosensitive hydrogels are known as injectable in situ gelling thermosensitive polymer solutions which are suitable for biomaterials. In this study, a novel thermosensitive hydrogel gelling under physiological conditions was prepared using chitosan together with hydroxypropyl methylcellulose and glycerol. Hydroxypropyl methylcellulose is to facilitate the thermogelation through large amounts of hydrophobic interactions. Glycerol in heavy concentration destroys the polymer water sheaths promoting the formation of the hydrophobic regions, and lowering the phase transition temperature. The thermosensitive hydrogels showed a physiological pH ranging from 6.8 to 6.9 and gelation time within 15 min at 37 °C. The prepared hydrogels were characterized by FT-IR, XRD, SEM, and rheological studies, mechanical studies and contact angle studies. The properties of degradability, cytotoxicity and protein release behaviors of the hydrogels were investigated. The results indicate this thermosensitive hydrogel possess good fluidity, thermosensitivity and biodegradability, as well as low-cytotoxicity and controlled release, showing the potential use in biomedical applications. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) biocomposites based on chitosan (CS) and clinoptilolite (CPL) were prepared by cryogelation and their potential application as drug carriers was investigated. Variation of CPL content from 0 to 33 wt.% allowed the formation of biocomposites with heterogeneous morphologies consisting of randomly distributed pores. The further increase of CPL content led to ordered porous architectures where parallel pore channels were observed. The CPL content had a strong influence on water uptake, as well as on the cumulative release of diclofenac sodium (DS) and indomethacin (IDM). It was demonstrated that the drug delivery preferentially takes place in phosphate buffer saline (pH 7.4) in comparison to simulated gastric fluid (pH 1.2), where only a reduced drug release was observed. The drug release mechanism dominating these systems is described as a pseudo-Fickian diffusion, but it changes to non-Fickian release when 33 wt.% of CPL was entrapped into the CS matrix or when IDM was loaded into biocomposites. [ABSTRACT FROM AUTHOR]

Chitosan (CS) and lauryl succinyl chitosan (LSC) particles were synthesized by ionic gelation to encapsulate high molecular weight proanthocyanidins (PAs) extracted from grape seed in an attempt to improve the cellular transport and delivery of the PAs. The extracts and particles were subjected to simulated gastrointestinal assays, cytotoxicity studies and cell permeation studies. The LSC and CS physicochemical properties were also evaluated and compared. The LSC particle sizes were 3640 ± 33 nm and the CS particles were 458 ± 11 nm; both were loaded with seed extract. The LSC released a lower PAs amount than the CS, protecting the encapsulated extract from the stomach pH. The cytotoxicity studies on HEK-293 cells showed that the half maxima inhibitory concentration (IC 50 ) of the raw extract was 0.006 mg/mL, and with the stabilization (on LSC or CS) this value increased to 1.7 mg/mL. The encapsulation of the extracts decreased their toxicity, allowing higher concentrations to be used. The transport studies through Caco-2 monolayer cells indicated the effective release of PAs from the particles. The phenols released by the LSC particles were significantly higher than that released by the native CS during the Caco- 2 cell permeation study. [ABSTRACT FROM AUTHOR]

Formulations of encapsulated oxytetracycline in chitosan spherical beads have been developed in this work through the ionotropic gelation method in sodium tripolyphosphate or tripolyphosphate and characterized as drug delivery system to the gastrointestinal tract by Fourier transform infrared spectroscopy, thermal analysis and in vitro drug release in simulated gastric fluids. The Fourier transform infrared spectroscopy and differential scanning calorimetry measurements showed that tripolyphosphate and tripolyphosphate are cross-linked ionically to chitosan and there was no significant drug interaction between the entrapped drug and the carrying polymer. With respect to chitosan cross-linking features, sodium hexametaphosphate seems to give better swelling, higher diffusion and faster release kinetics, while addition of glutaraldehyde as a second cross-linking agent lowers the drug discharge. Release extent and kinetics were found to be pH dependent and approximated very well by the multistep models equations of Makoid-Banakar, Peppas-Sahlin and Korsmeyer-Peppas. [ABSTRACT FROM AUTHOR]

Fundamental rheology, differential scanning calorimetry and infrared spectroscopy have been used to evaluate the effect of a cationic polysaccharide, chitosan, on the gelatinization, gel formation and retrogradation of maize starch samples, under acidic aqueous conditions. Moderate acidic conditions (0.1 mol L −1 acetic acid) have shown a (slight) positive effect on starch gelatinization process and structure development. The presence of chitosan increased the DSC onset gelatinization temperature and also shifted the onset of the storage modulus increase to higher temperatures. Formation of the starch gel, mainly gelation of the leached-out amylose, is somehow hindered by the presence of the cationic polysaccharide and, therefore, the retrogradation of starch at very early stage can be delayed by addition of chitosan. However, long-term retrogradation was slightly increased. FTIR pectroscopy did not reveal any significant interaction between both polysaccharides what is in accordance with the observed rheological behavior. Small additions of chitosan to starch-rich systems may be a useful strategy to obtain new textures with novel phase transition behaviors. [ABSTRACT FROM AUTHOR]

Objective Rutin, a potent antioxidant, has been reported to reduce the risk of ischemic disease. Our study aims to prepare rutin-encapsulated-chitosan nanoparticles (RUT-CS-NPs) via ionic gelation method and determine its results, based on different parameters i.e . surface morphology characterization, in-vitro or ex-vivo release, dynamic light scattering and differential scanning calorimetry (DSC), for treating cerebral ischemia. Methods UPLC-ESI-Q-TOF-MS/MS was used to evaluate the optimized RT-CS-NPs1 for brain-drug uptake as well as to follow-up the pharmacokinetics, bio-distrbution, brain-targeting efficiency and potential after intranasal administration (i.n.). Key findings A particle size of <100 nm for the formulation, significantly affected by drug:CS ratio, and entrapment efficiency and loading capacity of 84.98% ± 4.18% and 39.48% ± 3.16%, respectively were observed for RUT. Pharmacokinetics, bio-distribution, brain-targeting efficiency (1443.48 ± 39.39%) and brain drug-targeting potential (93.00 ± 5.69%) showed enhanced bioavailability for RUT in brain as compared to intravenous administration. In addition; improved neurobehavioral activity, histopathology and reduced infarction volume effects were observed in middle cerebral artery occlusion (MCAO) induced cerebral ischemic rats model after i.n. administration of RUT-CS-NPs. Conclusion A significant role of mucoadhesive-RT-CS-NPs1 as observed after high targeting potential and efficiency of the formulation prove; RUT-CS-NPs are more effectively accessed and target easily the brain. [ABSTRACT FROM AUTHOR]

Objective(s): An efficient vaccine against TB is an urgent need. TB peptides are safe candidate but they are weak immunogens and needs to be potentiated by adjuvant/delivery systems. The main purpose of the present study was to determine the potential of CHT based NPs containing ESAT-6 antigen of M. tuberculosis for inducing mucosal and systemic immune responses after intranasal and subcutaneous injection in mice model. Materials and Methods: CHT and TMC based NPs were prepared by coating of cationic polymer on the anionic peptide by ionic gelation method and their characteristics were evaluated by scanning electron microscopy (SEM) and dynamic light scattering (DLS). Physical stability of NPs was studied within 30 days. Finally, the ability of formulated NPs to elicit immune responses in BALB/c mice were evaluated following nasal and subcutaneous immunization. Results: The best weight ratio of antigen to polymer (CHT or TMC) was 1:2. CHT and TMC NPs had a mean size of 356.3 ± 42.20, and 470.3 ± 48.21 nm, respectively. NPs were stable up to 15 days. CHT:ESAT-6 NPs gave higher serum IgG1 and IgG total responses and TMC:ESAT-6 NPs induced high titers of IgG2a and IFN-γ. Conclusion: Regards to the importance of cellular immune responses in effective protection against TB, and also the solubility in physiological pH, TMC NPs are more efficient adjuvant/antigen delivery system for immunization against TB. [ABSTRACT FROM AUTHOR]

Background: There has been increased attention given to polymeric nanoparticles as protein carriers. In this regard, chitosan/tripolyphosphate (TPP) nanoparticles are considered to be a simple and efficient carrier. However, to have an ideal protein release profile, we need to optimize the properties of the carrier. Methods: This study examined the influence of 4 critical process parameters on the physicochemical characteristics of final nanoparticles. Chitosan-based nanoparticles were produced by ionic gelation, and then the size, polydispersity and zeta potential of those resulting nanoparticles were evaluated. Subsequently, the encapsulation efficiency of bovine serum albumin as model protein was investigated. Results: The morphologies of nanoparticles were characterized using field emission scanning electron microscopy (FE-SEM). Linear mathematical models were presented for each response through 3 levels using Central Composite Design with the help of design of experiments software, and formulation optimization was performed. Conclusions: Such research will serve as a basic study in protein loading into TPP cross-linked chitosan nanoparticles. [ABSTRACT FROM AUTHOR]

The present study was designed to investigate the use of different biopolymers in the formulation and release profile of Fluoxetine hydrochloride microspheres prepared by using ionotropic gelation method. Main purpose was comparing and selecting best suitable polymer among different polymers such as sodium alginate, chitosan, arabinoxylan and hydroxypropyl methylcellulose (HPMC). All the formulations were evaluated in terms of percentage yield, percentage encapsulation efficiency, flow properties, FTIR and SEM analysis and in vitro release characteristics. Percentage yield, encapsulation efficiency and flow properties of of all tested formulation were satisfactory. As far as in vitro drug release studies were concerned, F7 showed the best sustained release characteristics. Dissolution data modeling showed Krosmeyer peppas model following non-Fickian and super case II transport mechanism for drug release. In conclusion chitosan arabinoxylanin (2:1) are suitable polymer combination for microsphere formulation of Fluoxetine hydrochloride. [ABSTRACT FROM AUTHOR]

The present study examines the agrochemical application of macrospheres prepared with chitosan and chitosan-starch blends by an easy dripping technique, using a sodium tripolyphosphate aqueous solution as the crosslinking agent. These biopolymers form hydrogels that could be a viable alternative method to obtain controlled-release fertilizers (CRFs). Three different concentrations (ranging from 20 to 100 wt/wt% of chitosan) and two crosslinking times (2 or 4 h) were used. The resulting polymeric matrices were examined by scanning electron microscopy coupled with energy dispersive X-ray, X-ray diffraction, Fourier transform infrared spectroscopy, solid-state nuclear magnetic resonance, thermogravimetric analysis and differential scanning calorimetry. Ionotropic gelation and neutralization induced the formation of the macrospheres. The crosslinking time and the composition of the polymeric hydrogel controlled the crosslinking degree, the swelling behavior and the fertilizer loading capability. Potassium nitrate-loaded beads were shown to be useful as a controlled-release fertilizer. After 14 days of continuous release into distilled water, the cumulative concentration in the release medium reached between 70 and 93% of the initially loaded salt, depending on the matrix used. The prepared beads showed properties that make them suitable for use in the agrochemical industry as CRFs. [ABSTRACT FROM AUTHOR]

In this study, β-chitosan (CS) Maillard reaction (MR) NPs was prepared to improve the water solubility of CS NPs. The α- and β-CS MR was firstly induced by high intensity ultrasound-assisted (UA) water-bath heating at 80 °C for 8 h. The α- and β-CS Maillard reaction products (MRPs NPs were then prepared by ionic gelation method between the positively charged primary amino groups of CS and the negatively charged groups of sodium tripolyphosphate (TPP). The α- and β-CS MRPs NPs had particle size of 42.49 and 61.74 nm, and Zeta-potential of 27.43 and 35.13 mV, respectively. The prepared α- and β-CS MRPs NPs was characterized by transmission electron microscope (TEM), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA)-differential scanning calorimetry (DSC) to verify whether α- and β-CS MRPs has been incorporated into the CS NPs. The α- and β-CS MRPs NPs exhibited no significant difference (p > 0.05) in antioxidant activity compared with α- and β-CS MRPs at the same concentration based on reducing power, DPPH radical scavenging activity, and ORAC values. The cytotoxicity test of α- and β-CS MRPs NPs showed good cell viability (70.86–99.16%) of human pulmonary microvascular endothelial cells (HLMVEC) at the concentration range from 0.12 to 1 mg/mL, and fluorescein-5-isothiocyanate (FITC)-α- and β-CS MRPs NPs maintained the morphological characteristics of living cells. These results showed that α- and β-CS MRPs NPs can be used as water-soluble antioxidant substances for applications in food and other fields. [ABSTRACT FROM AUTHOR]

[Display omitted] • Encapsulated LEO was successfully produced by ionic gelation process. • Chitosan films with LEO microspheres and cranberry juice were developed. • The effect of LEO microspheres and cranberry juice in the films were investigated. • LEO microspheres and cranberry juice improved some of the chitosan film qualities. • Chitosan films with LEO microspheres and cranberry juice showed antimicrobial activity. Research about biodegradable antimicrobial films continues to receive a lot of attention due to the plastic pollution crisis and the need for environment-friendly and safe food products. In this study, we developed chitosan-based antimicrobial films using a combination of encapsulated lemon essential oil (LEO) by ionic gelation and cranberry juice and evaluated the performance of the films. Our results indicated that the incorporation of LEO microspheres and cranberry juice into the chitosan films improved the UV barrier and thermal properties as well as antioxidant activity of the films. The increase in antioxidants was consistent with the chemical components in LEO and cranberry juice as determined by GC–MS; some of which possess antioxidant properties. Furthermore, following antimicrobial activity test, considerable inhibition halo of 11 and 20 mm were observed respectively against fungi Candida albicans and Penicillium roqueforti , particularly in presence of the film containing both LEO microspheres and cranberry juice. [ABSTRACT FROM AUTHOR]

Upon heating and subsequent solvent displacement with pure water, the cold chitosan solution with aqueous alkaline/urea as solvent readily transforms into a hydrogel which is substantially stronger than traditional chitosan hydrogels regenerated from acidic solutions. In this work, we have systematically studied the effects of the treatment parameters in this two-step basic route and found that thermal gelation was the crucial step that dictated the structure and properties of the final gels. We hypothesized that the primary network formed in the thermal gelation step served as a template for the deposition of chitosan chains during solvent displacement, leading to a homogenous and compact structure. The primary network also provides crystalline seeds to facilitate the crystallization of the chitosan chains, leading to higher degree of crystallinity. This study provided a guideline for the preparation of chitosan hydrogels with high mechanical properties which is very meaningful to relevant research and applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The temperature-sensitive hydrogel (H/D) composed of hydroxybutyl chitosan (HBC) and diatom biosilica (DB) was prepared by physically mixing HBC solution with DB at low temperature. The rheological measurements confirmed that the incorporation of DB to hydroxybutyl chitosan could significantly enhance the mechanical strength of the hydrogels without disrupting its reversible phase transition behavior. The hierarchical porous structure of DB and its rich negatively charged surface provided penetration anchor points for HBC molecular chains, which significantly enhanced the mechanical properties of H/D. The gelation temperature, gelation time and mechanical strength could be easily regulated by change of the ratio of DB in composite hydrogel. The maximum storage modulus of HBC hydrogel was increased to 17 times after adding DB. H/D exhibited favorable blood compatibility (hemolysis rate < 5 %) and no cytotoxicity to L929 cells which are promising for the applications as tissue regeneration materials and wound dressing in biomedical fields. [Display omitted] [ABSTRACT FROM AUTHOR]

• Chitosan/silica hybrid 3D network scaffolds are obtained by an ionotropic process. • Two hydrophilic substances are simultaneously loaded within the scaffold structure. • The presence of nanostructured silica retards the release of the loaded substances. • Release profiles can be fitted to a dual model with diffusion and swelling terms. We report the preparation of a hybrid chitosan/silica three-dimensional (3D) scaffold loaded simultaneously with two model hydrophilic substances, ibuprofen sodium salt and erioglaucine disodium salt. The first substance is entrapped in situ during the preparation of chitosan submillimetric beads by ionotropic gelation with sodium triphosphate, while the latter is post-loaded during the scaffold formation. Controlled release experiments carried out under neutral conditions demonstrate that the presence of nanostructured silica within the polymer matrix retards the release of both hydrophilic substances and increases the structure stability of the scaffold. Release profiles can be fitted to a two-component model with a diffusion-controlled term (Korsmeyer-Peppas model), which dominates the release of the post-loaded substance, and a second swelling/erosion term, which becomes relevant for the in situ entrapped drug. [ABSTRACT FROM AUTHOR]

Hydrogels with injectability, self-healing ability and adhesiveness have great potential for hemostasis and full-thickness skin wound repair, which are usually fabricated by multistep chemical synthesis and the use of organic solvents and catalyst. Herein, we report an injectable and self-healing hydrogel facilely prepared through one-pot heating of chitosan and graphene oxide mixture solution, without any pollutant and waste generated. The dynamic reversible breakage and recombination of noncovalent bonds between chitosan and graphene oxide endows the hydrogel injectability and self-healing ability. In addition, the mechanical and rheological properties of the hydrogels can be controlled by varying the dosage of graphene oxide. Meanwhile, hydrogels exhibited good adhesiveness and hemocompatibility. Finally, in vivo experiments in a rat liver bleeding model and full-thickness skin defect model verified the outstanding hemostatic and wound healing capability of the hydrogels, indicating the promising future for use as wound dressing. [Display omitted] • CSGO hydrogels are facilely prepared by green fabrication strategy, without any pollutant and waste generated. • Gelation mechanism based on the variations of hydrogen bonds among CS chains and disordering degree of GO is proposed. • CSGO hydrogels have shear-thinning injectable, self-healing and adhesive properties. • CSGO hydrogels possess prominent hemostatic and wound healing capacity, have promising future for use as wound dressings. [ABSTRACT FROM AUTHOR]

An extracellular matrix (ECM) mimicking a 3D microenvironment is an essential requirement to achieve desirable repair or regeneration of damaged tissue or organ. In this context, hydrogels may be able to create an appropriate 3D microenvironment. The lack of mechanical stability limits their application. This study prepared and characterized thermosensitive injectable hydrogels based on chitosan and polygalacturonic acid (PgA). A method of producing novel biomimetic polymeric-based injectable hydrogel using hydrothermal assisted hydrolysis is introduced. The synthesized hydrogels showed good compressive stiffness. We have also studied the possible chemistry of the materials in the hydrogel network. The biocompatibility and gelation time of the hydrogel was optimized by adding β-glycerophosphate (βGP) and hydroxyapatite. The synthesized liquid formulation can turn into gel at 37 °C. The biocompatibility for MG63 cells within 3D hydrogels was investigated. Scanning electron microscopy revealed that the PEC fibers are uniformly distributed in the hydrogel matrix. MTT assay and confocal imaging were employed to observe cytotoxicity and proliferation of cells cultured in the hydrogels with and without an osteogenic medium. Alkaline phosphatase activity (ALP) and collagen production in cell-cultured hydrogel were also measured to evaluate osteoblast activity. The cellular responses to various types of hydrogels cultured at a 14-day culture appeared to be superior in the hydrogels with gelatin incorporated and hydrothermally treated PEC fibers. These results indicated that hydrothermal treatment and inclusion of gelatin in the chitosan-βGP hydrogel system enhanced the hydrogel bioactivity and mechanical properties. Overall, improved cellular proliferation, osteogenic differentiation, and stable physical network with uniform distribution of fibrous matrix in-vitro were achieved. [Display omitted] [ABSTRACT FROM AUTHOR]

As the forefront of the digestive system, a mouth in a high moist microenvironment is easy to breed bacteria and the inevitable injury from oral surgeries will cause a series of physiological disorders. The injectable hydrogels are promising biomaterials to solve this challenge, but the limited mechanical performance and weak mechanical adjustment are insufficient to fit in the whole healing process. Herein, we propose and design a new spatiotemporal self-strengthening injectable hydrogel via manipulating the time-dependent cross-linking effects after the Schiff base reaction. The resultant hydrogels possess various promising properties and functions, including rapid initial gelation efficiency (∼30 s), spatiotemporal adjustable mechanical strength, great antifouling property and biocompatibility, leading to effective promote oral tissue regeneration and bone repair. We believe both our concept and spatiotemporal self-strengthening injectable hydrogels will provide new insight into the hydrogel-based wound dressing and broaden the application of the bioinspired hydrogels in biomedical fields. [ABSTRACT FROM AUTHOR]

Food-grade microgel-stabilized emulsions have been attracting much attention due to their promising applications in food formulations. In this study, the use of hydrophobically modified chitosan microgels (h -CSMs) as particle emulsifiers to stabilize high internal phase emulsions (HIPEs) was demonstrated for the first time. Four hydrophobically modified chitosan (h -CS) were obtained by grafting deoxycholic acid (DA) with chitosan (CS) at grafting rates of 4.64%, 13.21%, 15.12% and 30.29%, respectively. The selected modified chitosan were further cross-linked with sodium tripolyphosphate (TPP) to form h -CSMs. It was found that, compared to pure CS and the modified h -CS, the h -CSMs have higher hydrophobicity, and can stabilize oil-in-water HIPEs effectively. The interfacial properties of the h -CSMs, and the formation, microstructure and rheological properties of HIPEs were characterized by dynamic interfacial adsorption, contact angle, visual observation, laser confocal microscopy and rheological measurements, respectively. The results show that stable HIPEs with oil concentration up to 90 wt% can be formed using very low h -CSM particle concentration (only 0.05 wt% for the HIPE with 90 wt% oil), and the HIPEs stabilized by h -CSMs displayed higher rheological compliance than other solid particle stabilized HIPEs at high oil volume fraction. The strong emulsification properties of the h -CSMs are attributed to their increased hydrophobicity, the enhanced exposure of hydrophobic groups during microgelation process, and the viscoelasticity of h -CSMs. [Display omitted] [ABSTRACT FROM AUTHOR]

The utilization of natural polymer gel to achieve drug polymorph control is usually a challenging issue, and the interplay of gelation and crystallization has been neglected in many studies. In this work, a modified chitosan (Cs) hydrogel was used to encapsulate drug Isonicotinamide (IN), where competitive crystallization and gelation was constructed for a better control of different assembly processes. It was found that the crystalline outcome of drug (cocrystals or IN Form I) depends on different crosslinking agents used. Spectral analysis and MD simulation reveal that the interplay of crosslinking effect of Cs, dimerization of crosslinking agents and aggregation of IN determines the crystalline outcome, among which the affinity to crosslinking agents of Cs chain plays the significant role. To our knowledge, it is the first time that Cs hydrogel acts as a template to regulate polymorphism of drug. This work offers a promising way for drug delivery system design. A drug-loaded chitosan hydrogel involving competitive gelation and nucleation was constructed，which paves the way for a new route to control the crystallization outcome of drug. [Display omitted] [ABSTRACT FROM AUTHOR]

The major limitations of typical thermogelling polymers for practical applications are low gel stability and weak mechanical properties under physiological conditions. In this study, we have synthesized a new polysaccharide-based thermogelling polymer that can be photo-crosslinked by UV irradiation to form a mechanically resilient and elastic hydrogel. Methacrylated hexanoyl glycol chitosan (M-HGC), was synthesized by a series of chemical modifications, N -hexanoylation and N -methacrylation, of glycol chitosan (GC). Various M-HGC polymers with different methacryl group contents were synthesized and their thermogelling and photo-crosslinkable properties were evaluated. The M-HGCs demonstrated a thermo-reversible sol–gel transition behavior in aqueous solutions. The thermally-induced hydrogels could be chemically crosslinked by UV-triggered photo-crosslinking. From the cytotoxicity studies using MTT and the live/dead assay, the M-HGC hydrogels showed non-cytotoxicity. These photo-crosslinkable thermogelling M-HGC polymers may hold great promises for various biomedical applications, such as an injectable delivery system and 3D cell culture. [ABSTRACT FROM AUTHOR]

Chitosan Oligosaccharide (COS) nanoparticles prepared by ionotropic gelation method using sodium tri-polyphosphate (Na-TPP) coated with Hyaluronic acid (HA). The coating confers biological advantage to the nanoparticles in terms improved circulation time in the plasma and targeting ability. This nanoparticulate system has potential application in targeted nucleic acid delivery as they can be tuned to possess overall cationic properties for binding anionic nucleic acids. In the present investigation, we studied the effect of COS of varying molecular weights on the formation COS-TPP nanoparticles coated with HA. Amongst them, COS with higher molecular weight resulted in formation of stable nanoparticles, along with TPP and HA. We also investigated the influence of molecular weight of COS on their physico-chemical properties, in particular, the ability to form nanoparticles with a narrow-size distribution. Furthermore, computational studies were conducted to understand molecular mechanism, which revealed that protonation modulates the behaviour of COS during formation of stable nanoparticles. [ABSTRACT FROM AUTHOR]

Biopolymers such as tragacanth, an anionic polysaccharide gum, can be alternative polymeric carrier for physiologically important peptides and proteins. Characterization of tragacanth is thus essential for providing a foundation for possible applications. Rheological studies colloidal solution of tragacanth at pH 3, 5 or 7 were carried out by means of steady shear and small amplitude oscillatory measurements. Tragacanth mucoadhesivity was also analyzed using an applicable rheological method and compared to chitosan, alginate and PVP. The particle size and zeta potential were measured by a zetasizer. Thermal properties of solutions were obtained using a differential scanning calorimetry. The solution exhibited shear-thinning characteristics. The value of the storage modulus ( G ′) and the loss modulus ( G ″) increased with an increase in angular frequency (Ω). In all cases, loss modulus values were higher than storage values ( G ″ > G ′) and viscous character was, therefore, dominant. Tragacanth and alginate showed a good mucoadhesion. Tragacanth upon dispersion created particles of a submicron size with a negative zeta potential (−7.98 to −11.92 mV). These properties were pH dependant resulting in acid gel formation at pH 3.5. Tragacanth has thus a potential to be used as an excipient for peptide/protein delivery. [ABSTRACT FROM AUTHOR]

Jumbo squid ( Dosidicus gigas) is characterised by its low commercial value, lean and white meat without bones or scales and high muscular yield. Therefore, it is an attractive species for the production of protein concentrates. However, the gelling ability of squid proteins is low due to the inherent characteristics of the proteins. Different hydrocolloids can be used to improve the gelling ability, where pH and concentration of the hydrocolloids are very important to stablish. Therefore, this study aimed to obtain a protein concentrate from Dosidicus gigas and evaluate the effect of pH and chitosan concentration on its gelation and conformational changes. Treatment at pH 7.0 with 2% chitosan improved the water-holding capacity, elasticity and agglomeration according to the Z potential; it also improved the thermal stability and gelling according to the dynamic oscillatory measurements and differential scanning calorimetry. This information demonstrates that chitosan incorporation plays an important role in gel formation and improves the gelling capacity of squid proteins without affecting the brightness and whiteness, important parameters for this product. [ABSTRACT FROM AUTHOR]

In this paper, ionic gelation method was adopted to produce nanocapsules (CNs) encapsulated tuberose fragrance with chitosan (CS) and sodium tripolyphosphate (TPP) as wall materials. The effects of CS/TPP mass ratio, pH value of CS solution, molecular mass of CS and tuberose fragrance (TF) concentration on particle size and particle size distribution (PDI) of chitosan nanocapsules encapsulated tuberose fragrance (CNTs) were investigated systematically. CNTs were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analyzer (TGA) and differential scanning calorimetry (DSC). The results showed that CNTs were successfully prepared. The optimum preparation conditions were as follows: CS/TPP mass ratio 5:1, pH of CS solution 4.0, and molecular mass of CS 150 kda. CNTs emulsions were also systematically investigated by steady-state shear and oscillatory shear measurements respectively. The rheological behaviors of CNTs were obtained. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the propensity of thiolated chitosan nanoparticles (TCNs) to enhance the nasal delivery of selegiline hydrochloride. TCNs were synthesized by the ionic gelation method. The particle size distribution (PDI), entrapment efficiency (EE), and zeta potential of modified chitosan (CS) nanoparticles were found to be 215 ± 34.71 nm, 70 ± 2.71%, and + 17.06 mV, respectively. The forced swim and the tail suspension tests were used to evaluate the anti-depressant activity, in which elevated immobility time was found to reduce on treatment. TCNs seem to be promising candidates for nose-to-brain delivery in the evaluation of antidepressant activity. [ABSTRACT FROM AUTHOR]

This work describes a gelation of chitosan solution with silver nitrate. Above the critical concentration of chitosan ( c *), continuous hydrogels of chitosan–silver can be formed. At lower concentrations, the formation of nano- and micro-hydrogels is discussed. The sol–gel analysis was performed to characterise the hydrogels’ swelling properties. Moreover, the following were employed: (i) mechanical testing of hydrogels, (ii) inductively coupled plasma-optical emission spectroscopy (ICP-OES) for the measurement of silver concentration, (iii) scanning electron microscopy (SEM) to examine the morphology of products obtained, and (iv) dynamic light scattering (DLS) and UV–vis spectrophotometry to examine products formed at low concentration of chitosan ( c < c *). Some hydrogels were used for modification of cotton fabric in order to give it antimicrobial properties. The products obtained acted against Escherichia coli and Bacillus subtilis apart from the chitosan used that showed no such activity. [ABSTRACT FROM AUTHOR]

In this paper, we present a system for an interactive control of micro-mixing and in-situ gelation of hydrogels. The performance and stability of micro-mixing in the system were simulated using the computer-aided finite element analysis. The fabricated system was tested to confirm the effectiveness of micro-mixing using Rhodamine B solution (RB), brilliant blue solution (BB), and deionized water (DW). The experimental results demonstrated that the system can effectively perform the micro-mixing of RB and BB solutions by changing the DW flow rates. The interactive control of micro-mixing and insitu gelation of N-carboxyethyl chitosan (NCC) and gelatin by oxidized dextran (ODX) was experimentally confirmed, resulting in a successful fabrication of in-situ gelable cellfree and cell-laden cylindrical microgels of a variety of lengths. The biocompatibility and non-cytotoxicity were demonstrated using human umbilical vein endothelial cells (HUVECs), showing a high cell viability. Therefore, the suggested system can serve as a highly effective tool for the fabrication of in-situ gelable cell-free or cell-laden cylindrical microgels in biomedical research. [ABSTRACT FROM AUTHOR]

Propranolol hydrochloride is sympatholytic nonselective beta blocker. It is used to treat hypertension, anxiety and panic. Propranolol loaded hydrogel beads were prepared using chitosan, sodium bicarbonate and glyoxal by ionotropic gelation method. The preformulation study performed on combination of drug with polymer by FT-IR suggested that they were compatible with each other. The formulation ofhydrogel beads were done by applying 32 full factorial design. The surface morphology studied by scanning electron microscope revealed irregular shape hydrogel beads. All prepared hydrogel beads were evaluated for particle size, drug entrapment efficiency, in-vitro releases study and swelling ratio. Optimized formulation showed good swelling in 0.1 N HCl up to 24 h maintaining the integrity of formulation. The in-vitro release of propranolol hydrochloride from optimized hydrogel beads was more than 80% in controlled manner. Hence it could be concluded that propranolol hydrochloride loaded hydrogel beads prepared by using combination of chitosan with glyoxal (crosslinking agent) sustained the release of propranolol HCl more than 24 h in a predetermined manner for the effective management of hypertension. [ABSTRACT FROM AUTHOR]

In medical and pharmaceutical applications, chitosan is used as a component of hydrogels–macromolecular networks swollen in water. Chemical hydrogels are formed by covalent links between the crosslinking reagents and amino functionalities of chitosan. To date, the most commonly used chitosan crosslinkers are dialdehydes, such as glutaraldehyde (GA). We have developed novel GA like crosslinkers with additional functional groups–dialdehyde derivatives of uridine (oUrd) and nucleotides (oUMP and oAMP)–leading to chitosan-based biomaterials with new properties. The process of chitosan crosslinking was investigated in details and compared to crosslinking with GA. The rates of crosslinking with oUMP, oAMP, and GA were essentially the same, though much higher than in the case of oUrd. The remarkable difference in the crosslinking properties of nucleoside and nucleotide dialdehydes can be clearly attributed to the presence of the phosphate group in nucleotides that participates in the gelation process through ionic interactions with the amino groups of chitosan. Using NMR spectroscopy, we have not observed the formation of aldimine bonds. It can be concluded that the real number of crosslinks needed to cause gelation of chitosan chains may be less than 1%. [ABSTRACT FROM AUTHOR]

Prompt and strong reconnection of severed peripheral nerves is crucial to nerve regeneration. The development of biocompatible nerve adhesives that are stronger than commonly used fibrin glue would be extremely beneficial to this field. We designed an in situ forming nerve adhesive hydrogel composed of chitosan and e-polylysine (PL), which mimics the polysaccharides/protein structure of natural epineurium matrices, thus, enhancing the compatibility with nerves. Michael-type addition between the maleimide and thiol group was employed as a cross-linking reaction to eliminate foreign damage to nerves and to ensure a fast hydrogel formation speed (curing speed). Gelation occurred within 10 s, quick enough to promptly seal the transected nerve. Catechol groups conjugated onto PL molecules were demonstrated to reinforce both the bulk cohesive force of the hydrogel and the interfacial adhesive force between the hydrogel and epineurium. The storage modulus of the hydrogel was elevated to more than 2400 Pa. A superior nerve adhesion property that can tolerate 0.185 N of force (8× higher than fibrin glue) was obtained. After 8 weeks, the morphology of the repaired nerve fiber coapted by our hydrogel was very close to the morphology of normal nerve, and the axon cross ratio of the regenerated nerves coapted using hydrogel (57%) was much higher than employing the suture technique (35%). Thus, the in situ rapid gelling system offers a promising approach to the repair of severed peripheral nerves. [ABSTRACT FROM AUTHOR]

The gelling behaviors of thiolated chitosan (TCS) in alkaline condition were investigated. Thioglycolic acid was conjugated onto chitosan backbone through amide bond formation. The variations of thiol group content were monitored in presence of H 2 O 2 or different pH values (pH 7.0, 8.0, 9.0) in dialysis mode. Different from the decreasing thiol group content upon time in acidic condition, increasing amount of thiol groups was detected in alkaline pH during 120 min dialysis attributed to alkaline hydrolysis of intra-molecular disulfide bonds. The extent of which was larger at higher pH values. Higher degree of thiolation, thiomer concentration or pH values promoted gelation of TCS. Entanglement and coagulation of chitosan molecule chains and re-arrangement of disulfide bonds acted closely and dynamically in the gelation process. Disulfide bonds, especially inter-molecular type, are formed by synergetic effects of thiol/disulfide interchange and thiol/thiol oxidation reactions. TCS coated vascular stent displayed wave-like microstructure of parallel ridges and grooves, which favored HUVECs adhesion and proliferation. The biocompatibility, peculiar morphology and thiol moieties of TCS as stent coating material appear application potential for vascular stent. [ABSTRACT FROM AUTHOR]

Antibiotic resistance against Gram-negative microbes is considered as an alarming phenomenon that needs to be addressed urgently to develop better therapeutic solutions. The aim of the present research work was to investigate and develop cefazolin loaded chitosan nanoparticles (CSNPs) as a potential tool against multidrug resistant pathogens. Empty and drug loaded CSNPs were prepared by ionic gelation method. It was observed by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) based studies that CSNPs were less than 100 nm in size and displayed homogeneity both in shape and size. Encapsulation of cefazolin has not increased the size of nano systems. Zeta sizer results revealed that both systems have positive zeta potential of more or less +50 mV, thus contributing towards a stable formulation. Encapsulation efficiency was directly proportional to the increase in the concentration of antibiotic (28–62%). Furthermore, growth kinetics study had demonstrated excellent antimicrobial potential of cefazolin loaded CSNPs against multi drug resistant Klebsiella pneumoniae , Pseudomonas aeroginosa and Extended Spectrum Beta Lactamase (ESBL) positive Escherichia coli. [ABSTRACT FROM AUTHOR]

Recently, stimuli-responsive nanocomposite-derived hydrogels have gained prominence in tissue engineering because they can be applied as injectable scaffolds in bone and cartilage repair. Due to the great potential of these systems, this study aimed to synthesize and characterize novel thermosensitive chitosan-based composites, chemically modified with collagen and reinforced by bioactive glass nanoparticles (BG) on the development of injectable nanohybrids for regenerative medicine applications. Thus, the composite hydrogels were extensively characterized by structural, morphological, rheological, and biological testing. The composites showed thermosensitive response with the gelation temperature at approximately 37 °C, which is compatible with the human body temperature. In addition, scanning electron microscopy (SEM) analysis indicated that the chitosan hydrogels exhibited 3D-porous structures, and the incorporation of collagen in the system caused increase on the average pore size. Fourier transform infrared spectroscopy (FTIR) analysis indicated the main functional groups of each component of the composite system and their chemical interactions forming the scaffold. Moreover, rheological measurements were employed to assess the viscoelastic behavior of the hydrogels as a function of the temperature. The results demonstrated that the addition of collagen and bioactive glass increases the mechanical properties after the gelation process. The addition of 2 wt.% of BG nanoparticles caused an increase of approximately 39% on stiffness compared to pure chitosan and the addition of 30 wt.% collagen caused a further increase on the stiffness by 95%. The cytotoxicity and cell viability of the hydrogels were assessed by MTT and LIVE/DEAD® assays, where the results demonstrated no toxic effect of the composites on the human osteosarcoma cell culture (SAOS) and kidney cells line of human embryo (HEK 293T). Hence, it can be stated that innovative composites were successfully designed and synthesized in this research with promising potential to be used as thermoresponsive biomaterials for bone-tissue bioapplications. [ABSTRACT FROM AUTHOR]

Colon-targeted capecitabine beads were formulated by an ionotropic gelation method. The sodium alginate to pectin ratio and chitosan concentration were optimized using a 32full factorial design. Analysis of response surface plots allowed the identification of an optimized formulation with high drug entrapment and controlled release. Insignificant differences in observed and predicted values for responses validated the optimization method. Optimized beads possessed an average diameter of 1395 µm and good flow properties. Their production as spherical beads having a smooth surface was confirmed by scanning electron microscopy. Fourier transform infrared spectroscopy revealed the compatibility of drug with added excipients, while differential scanning calorimetry study confirmed complete drug entrapment in polymer matrix. Higher swelling of beads in phosphate buffer pH 7.4 was obtained in comparison to pH 6.8. An in vitro wash off test indicated 70% mucoadhesion by the beads. In vitro dissolution studies of beads loaded into enteric-coated capsules revealed negligible release in simulated gastric and intestinal fluid, followed by 49.23% release in simulated colonic fluid, in 4 h. The optimized beads were found to be stable for three months at 25 ± 2°C/60 ± 5% RH. In conclusion, the formulated beads showed colon-specific controlled release properties, and thus could prove to be effective for colon cancer treatment. [ABSTRACT FROM AUTHOR]

In order to achieve prolong corneal contact time of norfloxacin (NFX) for treatment of extra ocular diseases, a pH triggered nanoparticulate in-situ gelling system was designed to explore dual advantage of nanoparticles and in-situ gelling system, for its ocular delivery. NFX loaded nanocarriers were developed by ionotropic gelation technique using chitosan as a matrix forming polymer, cross-linked by an anionic crosslinker sodium tripolyphosphate (TPP). Optimization of nanoformulations was done by 3² full factorial design using chitosan and TPP concentration(s) as the independent variables and particle size, % entrapment efficiency and % cumulative drug release as the responses. The experimental design was validated by extra design check point formulation (N10). The optimized formulation (N4) selected on the basis of highest desirability factor (0.895) was developed as in-situ gelling system using carbapol934 and evaluated. The best in-situ gelling formulation (N4G5) was sufficiently mucoadhesive, corneal toxicity, antibacterial activity and free from ocular irritancy. [ABSTRACT FROM AUTHOR]

Chitosan and alginate nano-composite (NP) carriers intended for colonic delivery containing prednisolone and inulin were obtained by two processes. Spray freeze-drying using chitosan (SFDC) or alginate (SFDA) was proposed as an alternative to the traditional chitosan-tripolyphosphate platform (CTPP). NPs were fully characterised and assessed for their yield of particles; level of prednisolone and inulin release in phosphate and Krebs buffers; and sensitivity to degradation by lysozyme, bacteria and faecal slurry. NPs based on chitosan showed similar properties (size, structure, viscoelastic behaviour), but those based on SFDC showed a higher mean release of both active ingredients, with similar efficiency of encapsulation and loading capacity for prednisolone but lower for inulin. SFDC was less degraded in the presence of lysozyme and E. coli and was degraded by B. thetaiotaomicron but not by faecal slurry. The results obtained with SFDA were promising because this NP showed good encapsulation parameters for both active ingredients and biological degradability by E. coli and faecal slurry. However, it will be necessary to use alginate derivatives to reduce its solubility and improve its mechanical behaviour. [ABSTRACT FROM AUTHOR]

Chitosan is a linear aminopolysaccharide that has been widely used for the formation of chitosan-based nanoparticles by ionic gelation with sodium tripolyphosphate (TPP). Often, the experimental design used to obtain these systems does not take into consideration important variables, such as the degree of acetylation (DA) and the molecular weight ( M w ) of chitosan. In this work, we studied the formation of chitosan-TPP nanoparticles with chitosan samples of varying DA and M w (DA0 ∼ 0–47% and M w ∼ 2.5–282 kDa). We addressed the influence the degree of space occupancy and the degree of crosslinking on the physical properties of chitosan-TPP nanoparticles. Nanoparticles that comprised chitosan of DA ∼ 0–21.7% behaved differently than those made of chitosan of DA ∼ 34.7–47%. We attributed these differences to the polymer conformation and chain flexibility of the distinct chitosans in solution. Moreover, chitosan of high M w were found to have a stronger preference for incorporating into the formed nanoparticles than do low- M w ones, as determined by SEC-HPLC. These results open new perspectives to understand the formation of chitosan nanoparticles by the ionic gelation technique. [ABSTRACT FROM AUTHOR]

The aim of this investigation is to combine the advantages of pluronic ® F127 hydrogels and nanoparticles composed of poly(isobutylcyanoacrylate) (PIBCA) core coated with a mixture of chitosan and thiolated chitosan to design novel multifunctional formulation for mucosal application. Nanoparticles offer the advantage of being mucoadhesive while pluronic ® F127 hydrogel allowed prolonged contact time onto mucosal surfaces. This work highlights an unprecedented comprehensive study on the effect of nanoparticles on gelation and micellization behaviors of pluronic ® F127 using rheology and micro-calorimetry experiments. Results showed that presence of nanoparticles induced (i) smaller crystal peak of F127, (ii) a decrease of the enthalpy of F127 micellization and (iii) a non-reversibility of micelle formation (during heating ramp) and micelle melting (during cooling ramp). Together, these findings suggest that a part of F127 was not able to associate into micelles and the formation of mixed micelles containing F127 unimers and PIBCA/(chitosan/thiolated chitosan) copolymer and/or PIBCA homopolymer was suspected. The interaction of F127 unimers with nanoparticles resulted from their physical de-structuration as revealed by nanoparticle size measurement. In addition, we found that short polymerization duration of one hour induced more pronounced nanoparticle de-structuration. Twenty-four hour-polymerization of isobutylcyanoacrylate in the presence of chitosan and thiolated chitosan led to more stable nanoparticles when mixed with pluronic ® F127. [ABSTRACT FROM AUTHOR]

Orally dispersing tablets (ODTs), also known as orodispersibles, were first introduced into the market in 1980s to overcome dysphagia problems amongst pediatrics and geriatrics. Despite their abilities to avoid swallowing difficulties, frequency of dosing stood as a barrier for these formulations. The aim of the current study is to produce and optimize a sustained release orally disintegrating tablets (SR-ODT), with the aid of chitosan. A design of experiment (DoE) was first performed using Minitab to determine the effect of five independent variables on three dependent responses when producing the nanoparticles using ionotopic gelation. The variables studied were (tripolyphosphate concentration TPP, chitosan concentration CS, acetic acid concentration, chitosan: tripolyphosphate ratios and stirring time) and the responses were (particle size, surface charge and encapsulation efficiency). A formulation with optimum particle size, surface charge and encapsulation efficiency was prepared and further coated with polyvinylpyrolidine (PVP), polyethylene glycol (PEG) and polyethylene co-acrylic acid (PEAA). Minitab studies revealed that the nanoparticles’ particle size was affected by most of the independent variables except stirring time and the ratios of CS to TPP. The optimized nanoparticles showed particle size of 153.8 ± 14 nm, surface charge of 31.4 ± 0.9 mV and encapsulation efficiency of 99.7 ± 0.06%. The DSC showed that PMZ was solubilized within chitosan nanoparticle, whereas SEM images indicated that all the samples were spherical in shape with smooth surface and had similar size to that measured by DLS. After coating and dispersing into the tablets’ matrices, the tablets were evaluated to determine their friability, disintegration time and tensile strength. All tablets were at an appropriate friability (less than 1%) and had tensile strength above 2.5 N/mm 2 . Besides, all the tablets managed to disintegrate within 40 s whilst sustaining the drug release over 24 h. [ABSTRACT FROM AUTHOR]

Trans-cinnamaldehyde incorporated chitosan-alginate nanoparticles were synthesized using the ionic gelation and polyelectrolyte complexation technique. Alginate, chitosan, calcium chloride, and trans-cinnamaldehyde at predetermined concentrations were complexed electrostatically to optimize particle size and loading efficiency. A final methodology using optimized processing parameters (for example, stirring time, homogenization time, equilibration time, and droplet size) was developed. The best working alginate to chitosan mass ratio was determined to be 1.5:1 at a pH dispersion of 4.7. Particle size (166.26 nm) and encapsulation efficiency (73.24%) were further optimized at this mass ratio using an alginate:calcium chloride mass ratio of 4.8:1, alginate: trans-cinnamaldehyde mass ratio of 37.5:1, a 18 gauge syringe needle, stirring times of 90 min, 15 min of homogenization at 21000 rpm, and equilibration time of 24 h. Optimized nanoparticles showed increased stability (6 wk) and translucency in solution. The final radical scavenging effect of loaded particles in apple juice was 62% and trans-cinnamaldehyde was just as available to react in free form as it was in inclusion complexes. The final nanoparticle system with modified and optimized processing parameters reduced the size by 43.6% and increased entrapment efficiency by 17.2%. Nanoparticles resembled a spherical shell and core type arrangement (that is, spherical, distinct, and regular) and were in the size range of 10 to 100 nm. [ABSTRACT FROM AUTHOR]

We report on intriguing new phenomena related to the creation of chitosan hydrogels crosslinked with genipin. We found that the reaction between chitosan and genipin is very slow, sometimes requiring more than four days until completed. Further, we discovered that altering the pH within the small range of 4.00–5.50 dramatically affects the reaction, leading to hydrogels differing both in appearance and in properties. Increasing the pH by 1.5 units led to an almost fourfold decrease in the gelation time and more than tenfold equilibrium swelling. A correlation between the percentage of unreacted genipin molecules and the hydrogel properties was identified. The strong pH dependency was attributed to the degree of chitosan protonation and to the inability of protonated chitosan to react with genipin. This research shows, for the first time, that minor changes in the pH can lead to substantially different hydrogels. [ABSTRACT FROM AUTHOR]

In this study, a fucoidan-shelled chitosan bead was developed with the purpose of oral delivery of berberine to inhibit the growth of bacteria. The cross-linking level and swelling property of the beads were affected by the pH value and the composition of the genipin/fucoidan combined gelling agent. The drug release of the berberine-loaded beads was faster in simulated gastric fluid (pH 1.2) than those in simulated intestinal fluid (pH 7.4). Furthermore, a nanoparticles/beads complex system was developed by incorporation of berberine-loaded chitosan/fucoidan nanoparticles in the fucoidan-shelled chitosan beads. The nanoparticles/beads complex served as a drug carrier to delay the berberine release in simulated gastric fluid, with an estimated lag time of 2 h. Our results showed that the berberine-loaded beads and nanoparticles/beads complex could effectively inhibit the growth inhibition of common clinical pathogens, such as Staphylococcus aureus and Escherichia coli , and have the advantage of continually releasing berberine to inhibit the growth of the bacteria over 24 h. [ABSTRACT FROM AUTHOR]

The chemical potentials of drug–polymer electrostatic interaction have been utilized to develop a novel ternary chitosan–ibuprofen–gellan nanogel as controlled transdermal delivery tool for ibuprofen. The ternary nanogels were prepared by a combination of electrostatic nanoassembly and ionic gelation techniques. The electrostatic and hydrophobic interactions as well as hydrogen bonding between ibuprofen and chitosan were confirmed with FTIR, while DSC, TGA and SEM confirmed the physical state, thermal and morphological characteristics, respectively. The ex vivo delivery of ibuprofen onto and across the skin was evaluated based on system specific drug release parameters such as steady state permeation rate, permeability coefficient, permeability enhancement ratio, skin/gel partition coefficient, diffusion coefficient, lag time and release rate constant and mechanisms of release were determined using mathematical models. Interaction between ibuprofen and chitosan produced new spherical eutectic nanoconjugates with remarkable decrease in particle size of ibuprofen from 4580 (length-to-breadth aspect ratio) to a minimum of 14.15 nm (324-times), and thermally stable amorphous characteristics. The nanogels exhibited significant elastic and pseudoplastic characteristics dictated by the concentration of chitosan with maximum swelling capacity of 775% w/w at 6.55 mM chitosan compared with 281.16 and 506.50% for plain gellan and control ibuprofen hydrogel, respectively. Chitosan enhanced the skin penetration, permeability and the rate of transdermal release of ibuprofen by a factor of 4, dictated by the extent of ibuprofen–chitosan ionic interaction and its concentration. The major mechanism of ibuprofen release through the pig skin was drug diffusion however drug partition and matrix erosion also occurred. It was evident that ternary nanogels are novel formulations with potential application in controlled transdermal delivery of ibuprofen. [ABSTRACT FROM AUTHOR]

The structural properties of medium molecular weight chitosan (CHT), whey protein isolate (WPI) and native wheat starch (WS) from low- to intermediate-solid single systems and composite matrices were investigated. Analysis involved monitoring the thermal behavior of these biopolymers during controlled heating from 25 up to 95 °C and subsequent cooling to 5 °C under small deformation dynamic oscillation in-shear and micro differential scanning calorimetry experiments. Further information regarding the molecular interactions of components and overall network morphology of the systems was revealed through subjecting thermally developed gels to large deformation compression testing, scanning electron microscopy and infrared spectroscopy. Our study found a significant change in the structure of WPI networks upon incorporation of CHT in preparations due to electrostatic forces developing between the two polymeric constituents. In the tertiary system, the presence of low levels of starch contributed to a reduction in the firmness of the gel matrix. However, at higher additions of the polysaccharide, a recovery in the stored energy of composite materials was apparent, as recorded in the thermomechanical protocol. [ABSTRACT FROM AUTHOR]