Preparation and blood coagulation evaluation of chitosan microspheres

Preparation and characterization of amidated pectin-gelatin-oxidized tannic acid hydrogel films supplemented with in-situ reduced silver nanoparticles for wound-dressing applications

Wound dressings play a crucial role in protecting injured tissues and promoting the healing process. Traditional fabrication of antibacterial wound dressings can be complex and may involve toxic components. In this study, we developed an innovative hydrogel film (AP:GE@OTA/Ag) composed of amidated pectin (AP), gelatin (GE), oxidized tannic acid (OTA) at varying concentrations, and in-situ reduced silver nanoparticles (AgNPs). FTIR and XRD analyses confirmed that crosslinking occurs via interactions between OTA quinone groups and free amino groups in AP and GE. TEM imaging demonstrated the well-dispersed AgNPs with an average particle size of 58.64 nm, while the TG measurements indicated the enhancement of the thermal stability compared to AP:GE films. The AP:GE@OTA/Ag films exhibited superior fluid uptake ability (90.96 % at 2 h), water retention capacity (91.69 % at 2 h), and water vapor transmission rate (1903.29 g/m2/day), alongside improved tensile strength (38 MPa). Additionally, these films showed excellent cytocompatibility and sustained potent antimicrobial activity against S. aureus and E. coli with low AgNPs loadings of 1.02 ± 0.13 μg/cm2. NIT-1 mouse insulinoma cells demonstrated robust proliferation when cultured with the prepared dressings. These films significantly accelerated wound repair in a skin excision model, indicating their potential clinical applications for wound healing.

Chitosan Poly(vinyl alcohol) Methacrylate Hydrogels for Tissue Engineering Scaffolds

A major challenge in tissue engineering scaffolds is controlling scaffold degradation rates during healing while maintaining mechanical properties to support tissue formation. Hydrogels are three-dimensional matrices that are widely applied as tissue scaffolds based on their unique properties that can mimic the extracellular matrix. In this study, we develop a hybrid natural/synthetic hydrogel platform to tune the properties for tissue engineering scaffold applications. We modified chitosan and poly(vinyl alcohol) (PVA) with photo-cross-linkable methacrylate functional groups and then synthesized a library of chitosan PVA methacrylate hydrogels (ChiPVAMA) with two different photoinitiators, Irgacure 2959 (I2959) and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP). ChiPVAMA hydrogels showed tunability in degradation rates and mechanical properties based on both the polymer content and photoinitiator type. This tunability could enable their application in a range of tissue scaffold applications. In a 2D scratch wound healing assay, all hydrogel samples induced faster wound closure compared to a gauze clinical wound dressing control. NIH/3T3 cells encapsulated in hydrogels showed a high viability (∼92%) over 14 days, demonstrating the capacity of this system as a supportive cell scaffold. In addition, hydrogels containing a higher chitosan content demonstrated a high antibacterial capacity. Overall, ChiPVAMA hydrogels provide a potential tissue engineering scaffold that is tunable, degradable, and suitable for cell growth.

A hemostatic sponge derived from chitosan and hydroxypropylmethylcellulose

Hemostatic materials are of great significance for rapid control of bleeding, especially in military trauma and traffic accidents. Chitosan (CS) hemostatic sponges have been widely concerned and studied due to their excellent biocompatibility. However, the hemostatic performance of pure chitosan sponges is poor due to the shortcoming of strong rigidity. In this study, CS and hydroxypropylmethylcellulose (HPMC) were combined to develop a safe and effective hemostatic composite sponges (CS/HPMC) for hemorrhage control by a simple mixed-lyophilization strategy. The CS/HPMC exhibited excellent flexibility (the flexibility was 74% higher than that of pure CS sponges). Due to the high porosity and procoagulant chemical structure of the CS/HPMC, it exhibited rapid hemostatic ability in vitro (BCI was shortened by 50% than that of pure CS sponges). The good biocompatibility of the obtained CS/HPMC was confirmed via cytotoxicity, hemocompatibility and skin irritation tests. The CS/HPMC can induced the erythrocyte and platelets adhesion, resulting in significant coagulation acceleration. The CS/HPMC had excellent performance in vivo assessments with shortest clotting time (40 s) and minimal blood loss (166 mg). All above results proved that the CS/HPMC had great potential to be a safe and rapid hemostatic material.

An architecturally rational hemostat for rapid stopping of massive bleeding on anticoagulation therapy

Hemostatic devices are critical for managing emergent severe bleeding. With the increased use of anticoagulant therapy, there is a need for next-generation hemostats. We rationalized that a hemostat with an architecture designed to increase contact with blood, and engineered from a material that activates a distinct and undrugged coagulation pathway can address the emerging need. Inspired by lung alveolar architecture, here, we describe the engineering of a next-generation single-phase chitosan hemostat with a tortuous spherical microporous design that enables rapid blood absorption and concentrated platelets and fibrin microthrombi in localized regions, a phenomenon less observed with other classical hemostats without structural optimization. The interaction between blood components and the porous hemostat was further amplified based on the charged surface of chitosan. Contrary to the dogma that chitosan does not directly affect physiological clotting mechanism, the hemostat induced coagulation via a direct activation of platelet Toll-like receptor 2. Our engineered porous hemostat effectively stopped the bleeding from murine liver wounds, swine liver and carotid artery injuries, and the human radial artery puncture site within a few minutes with significantly reduced blood loss, even under the anticoagulant treatment. The integration of engineering design principles with an understanding of the molecular mechanisms can lead to hemostats with improved functions to address emerging medical needs.

Chitosans and Nanochitosans: Recent Advances in Skin Protection, Regeneration, and Repair

Chitosan displays a dual function, acting as both an active ingredient and/or carrier for pharmaceutical bioactive molecules and metal ions. Its hydroxyl- and amino-reactive groups and acetylation degree can be used to adjust this biopolymer's physicochemical and pharmacological properties in different forms, including scaffolds, nanoparticles, fibers, sponges, films, and hydrogels, among others. In terms of pharmacological purposes, chitosan association with different polymers and the immobilization or entrapment of bioactive agents are effective strategies to achieve desired biological responses. Chitosan biocompatibility, water entrapment within nanofibrils, antioxidant character, and antimicrobial and anti-inflammatory properties, whether enhanced by other active components or not, ensure skin moisturization, as well as protection against bacteria colonization and oxidative imbalance. Chitosan-based nanomaterials can maintain or reconstruct skin architecture through topical or systemic delivery of hydrophilic or hydrophobic pharmaceuticals at controlled rates to treat skin affections, such as acne, inflammatory manifestations, wounds, or even tumorigenesis, by coating chemotherapy drugs. Herein, chitosan obtention, physicochemical characteristics, chemical modifications, and interactions with bioactive agents are presented and discussed. Molecular mechanisms involved in chitosan skin protection and recovery are highlighted by overlapping the events orchestrated by the signaling molecules secreted by different cell types to reconstitute healthy skin tissue structures and components.

Multifunctional hydrogels based on oxidized pectin and gelatin for wound healing improvement

Gelatin (G) cross-linked with oxidized pectin (OP) was studied as a potential scaffold material for tissue engineering. The effect of oxidation on the chemical properties of pectin was investigated by determining the carbonyl and carboxyl amounts. The OP treatment led to a significant decrease of all values (Mn, Mw, [η] and Rh) determined by size exclusion chromatography (SEC) coupled on line with multiangle light scattering and viscometer detectors. Cross-linking parameters were elucidated by FTIR and TNBS assay. In general, the degree of crosslinking increased with the oxidation of pectin. It was found that the presence of the crosslinking agents caused a reduction in swelling and in the gelatin release which was determined by the BCA kit assay. From the hemolysis test, the membrane of red blood cells was not disrupted by the contact of films and the rate of release of hemoglobin was lower than 5%. The coagulation properties were evaluated by the dynamic blood clotting test. The G/OP hydrogels manifested a good activity of wound healing in the albino rats' model. Moreover, the films did not produce any unwilling symptoms. So, it was concluded that studied films have the potentiality to be used as wound healing biomaterials.

Hemostasis Evaluation of Antibacterial and Highly Absorbent Composite Wound Dressings in Animal Hemostasis Models

To reduce the bleeding time and to shorten the surgery time are vital to patients' prog-nosis, therefore, in this study, high moisture absorption nonwoven composites are proposed to attain hemostasis in time. Polyacrylate fiber and Tencel^® fibers at different blending ratios (10:90, 20:80, 30:70, 40:60, and 50:50) are used to form PT composite nonwoven. Next, composed of a 50:50 ratio, PT composite nonwoven exhibits the maximal vertical wicking height of 4.4 cm along the cross direction. Additionally, the UV-Vis absorption spectra analysis shows that at absorption waves of 413-415 nm, the occurring of distinct peaks suggests the presence of nanoparticles. The XRD patterns indicate the presence of silver nanoparticles with corresponding crystal planes of characteristic peaks at (111), (200), and (220). Polyacrylate/Tencel^® nonwoven composites exhibit comparable adsorption capacity of blood and water molecules. In particular, 30PT composite nonwoven outperforms the control group, exhibiting 3.8 times and 4.7 times greater the water absorption and blood absorption, respectively. Moreover, a great number of red blood cells with a size of 4-6 μm agglomerate among fibers as observed in SEM images, while 6hr-PT composite dressing demonstrates the optimal antibacterial efficacy against Escherichia coli and Staphylococcus aureus, proven by the zone of inhibition being 1.9 mm and 0.8 mm separately. When in contact with plasma, hemostasis composites have plasma hemostasis prothrombin time of 97.9%, and activated partial thromboplastin time of 96.7%. As for animal hemostasis model, the arteria over the rats' thigh bones is cut open perpendicularly, generating mass arteria hemorrhage. To attain hemostasis, it takes 46.5% shorter time when using composite dressings (experimental group) than the control group.

Effects of degree of deacetylation on hemostatic performance of partially deacetylated chitin sponges

Chitin/chitosan hemostatic materials have long been studied for uncontrolled hemorrhage, an urgent clinical problem due to severe blood-vessel damage or hemophilia. As one of the basic structural parameters of chitin, the degree of deacetylation (DD) significantly affects the material's physical, chemical, as well as biological properties. In this study, partially deacetylated chitins with a wide range of DD (23-81%) were prepared by homogeneous deacetylation, and sponges with these various chitins were fabricated by freeze-drying to study the effects of DD on their hemostatic properties. Among all sponge samples, the chitosan sponge with a DD of 48% showed the highest water absorption, whole blood adsorption, RBC adsorption rate, and the best hemostatic performance in an uncontrolled bleeding model of the rat femoral artery, demonstrating that a certain proportion of acetyl amino and amino groups could also activate the coagulation system and promote the adhesion of platelet and erythrocyte.

An Injectable Hybrid Gelatin Methacryloyl (GelMA)/Phenyl Isothiocyanate-Modified Gelatin (Gel-Phe) Bioadhesive for Oral/Dental Hemostasis Applications

Biomaterials are widely used for effectively controlling bleeding in oral/dental surgical procedures. Here, gelatin methacryloyl (GelMA) was synthesized by grafting methacrylic anhydride on gelatin backbone, and phenyl isothiocyanate-modified gelatin (Gel-Phe) was synthesized by conjugating different gelatin/phenyl isothiocyanate molar ratios (G/P ratios) (i.e., 1:1, 1:5, 1:10, 1:15, 1:25, 1:50, 1:100, and 1:150) with gelatin polymer chains. Afterward, we combined GelMA and Gel-Phe as an injectable and photo-crosslinkable bioadhesive. This hybrid material system combines photo-crosslinking chemistry and supramolecular interactions for the design of bioadhesives exhibiting a highly porous structure, injectability, and regulable mechanical properties. By simply regulating the G/P ratio (1:1-1:15) and UV exposure times (15-60 s), it was possible to modulate the injectability and mechanical properties of the GelMA/Gel-Phe bioadhesive. Moreover, we demonstrated that the GelMA/Gel-Phe bioadhesive showed low cytotoxicity, a highly porous network, and the phenyl-isothiourea and amine residues on Gel-Phe and GelMA polymers with synergized hemostatic properties towards fast blood absorption and rapid clotting effect. An in vitro porcine skin bleeding and an in vitro dental bleeding model confirmed that the bioadhesive could be directly extruded into the bleeding site, rapidly photo-crosslinked, and reduced blood clotting time by 45%. Moreover, the in situ crosslinked bioadhesive could be easily removed from the bleeding site after clotting, avoiding secondary wound injury. Overall, this injectable GelMA/Gel-Phe bioadhesive stands as a promising hemostatic material in oral/dental surgical procedures.

An injectable, dual crosslinkable hybrid pectin methacrylate (PECMA)/gelatin methacryloyl (GelMA) hydrogel for skin hemostasis applications

Biomaterials for effective hemorrhage control are urgently needed in clinics as uncontrolled bleeding is associated with high mortality. Herein, we developed an injectable and in situ photo-crosslinkable hybrid hemostatic hydrogel by combining pectin methacrylate (PECMA) and gelatin methacryloyl (GelMA). This modular material system combines ionic- and photo-crosslinking chemistries to design interpenetrating networks (IPN) exhibiting tunable rheology, highly porous structure, and controllable swelling and mechanical properties. By simply changing the calcium (0-15 mM) and polymer (1.5-7%) content used for the sequential crosslinking of hydrogels via calcium gelation and UV-photopolymerization, it was possible to precisely modulate the injectability, degradation, and swelling ratio. Moreover, it is demonstrated that PECMA/GelMA hydrogels present good cytocompatibility and uniquely synergize the hemostatic properties of calcium ions on PECMA, the amine residues on GelMA, and the highly porous network toward rapid blood absorption and fast coagulation effect. An in vitro porcine skin bleeding model confirmed that the hydrogel could be directly injected into the wound and rapidly photo-crosslinked, circumventing the bleeding and decreasing the coagulation time by 39%. Importantly, the crosslinked hydrogel could be easily removed to prevent secondary wound injury. Overall, this injectable hybrid PECMA/GelMA hydrogel stands as a promising hemostatic material.

Chitosan-Based Functional Materials for Skin Wound Repair: Mechanisms and Applications

Skin wounds not only cause physical pain for patients but also are an economic burden for society. It is necessary to seek out an efficient approach to promote skin repair. Hydrogels are considered effective wound dressings. They possess many unique properties like biocompatibility, biodegradability, high water uptake and retention etc., so that they are promising candidate materials for wound healing. Chitosan is a polymeric biomaterial obtained by the deacetylation of chitin. With the properties of easy acquisition, antibacterial and hemostatic activity, and the ability to promote skin regeneration, hydrogel-like functional wound dressings (represented by chitosan and its derivatives) have received extensive attentions for their effectiveness and mechanisms in promoting skin wound repair. In this review, we extensively discussed the mechanisms with which chitosan-based functional materials promote hemostasis, anti-inflammation, proliferation of granulation in wound repair. We also provided the latest information about the applications of such materials in wound treatment. In addition, we summarized the methods to enhance the advantages and maintain the intrinsic nature of chitosan via incorporating other chemical components, active biomolecules and other substances into the hydrogels.

Biocompatibility and in vivo degradation of chitosan based hydrogels as potential drug carrier

Carboxymethyl chitosan-graft-polylactide (CMCS-PLA) and carboxymethyl chitosan (CMCS) hydrogels were prepared by using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) as crosslinking agent and catalyst at room temperature. The biocompatibility of the hydrogels was evaluated with the aim of assessing their potential as drug carrier. Various aspects of biocompatibility were considered, including MTT assay, agar diffusion test, release of lactate dehydrogenase (LDH), hemolytic test, plasma recalcification time (PRT), and dynamic clotting time. MTT assay showed that the cytotoxicity level of both hydrogels to L-929 cells was 0 or 1. The LDH release of CMCS and CMCS-PLA was 26 and 29%, respectively, which is slightly higher than that of the negative control (21%) and much lower than that of the negative control (87%). The hemolysis ratio of CMCS and CMCS-PLA was 1.4 and 1.7%, respectively, suggesting outstanding anti-hemolysis properties of both materials. The PRT value of CMCS and CMCS-PLA was higher by 77 and 99% than the value of the positive control. All the results revealed that the hydrogels present good cytocompatibility and hemocompatibility in vitro. In vivo degradation and tissue compatibility were evaluated by subcutaneous injection in the dorsal area of rats. CMCS and CMCS-PLA hydrogels were completely degraded and the inflammatory response also completely disappeared around hydrogels after 19 days in vivo. It is thus concluded that hydrogels formed of CMCS and CMCS-PLA with outstanding biocompatibility are promising as potential drug carrier.

Study on the morphological and biocompatible properties of chitosan grafted silk fibre reinforced PVA films for tissue engineering applications

The current study delineates the preparation of novel chitosan grafted silk fibre reinforced Poly (vinyl alcohol) (PVA) composite films with desirable properties. Although silk fibroin has been extensively used for various biomedical applications, its properties could be further re-tailored for its suitability in the field of regenerative medicine. Chitosan was successfully grafted over silk, via acylation with succinic anhydride and thereby the fibres were incised and used for the preparation of the films. The grafted silk fibre reinforced PVA films were subjected to FTIR studies, microscopic analysis by atomic force microscopy (AFM) and optical microscopy techniques, X-ray diffraction (XRD) analysis and further evaluated for in vitro biocompatibility studies. The composite films demonstrated improved surface roughness with increasing concentration of the fibre and its dispersion in the polymer matrix was observed. Furthermore, in vitro biocompatibility and cellular behaviour such as adhesion and proliferation of mouse fibroblasts as well as astrocyte cells was studied and the results showed improved proliferative activity, when compared to the pristine PVA films. These results were further supported by the results confirmed by MTT assay demonstrating the films to be non-toxic. The efficiency and feasibility of the films to be used for tissue engineering, was further evaluated by haemocompatibility studies using human erythrocytes, thus making them a potential material to be used for biomedical applications.

Temperature-Sensitive Gold Nanoparticle-Coated Pluronic-PLL Nanoparticles for Drug Delivery and Chemo-Photothermal Therapy

Gold nanoparticle-coated Pluronic-b-poly(L-lysine) nanoparticles (Pluronic-PLL@Au NPs) were synthesized via an easy one-step method and employed as carriers for the delivery of paclitaxel (PTX) in chemo-photothermal therapy, in which Pluronic-PLL acts as the reductant for the formation of AuNPs without the need for an additional reducing agent.

METHODS

The deposition of AuNPs on the surface of Pluronic-PLL micelles and the thermal response of the system were followed via ultraviolet-visible spectroscopy and dynamic light scattering. Calcein-AM and MTT assays were used to study the cell viability of MDA-MB-231 cells treated with PTX-loaded Pluronic-PLL@Au NPs, and we then irradiated the cells with NIR light.

RESULTS

An obvious temperature response was observed for the Pluronic-PLL@Au NPs. Blood compatibility and in vitro cytotoxicity assays confirmed that the Pluronic-PLL@Au NPs have excellent biocompatibility. Compared to Taxol, the PTX-loaded Pluronic-PLL@Au NPs exhibited higher cytotoxicity in MDA-MB-231 cells. All of these results and confocal laser scanning microscopy analysis results suggest that Pluronic-PLL@Au NPs greatly enhance the cellular uptake efficiency of the drug.

CONCLUSION

As confirmed by in vitro and in vivo studies, the combination of chemotherapy and photothermal therapy can cause more damage than chemo- or photothermal therapy did alone, demonstrating the synergistic effect of chemo-photothermal treatment. Thus, the as-prepared Pluronic-PLL@Au NPs are promising for chemo-photothermal therapy.

Nanomedicine: Interaction of biomimetic apatite colloidal nanoparticles with human blood components

This contribution investigates the interaction of two types of biomimetic-apatite colloidal nanoparticles (negatively-charged 47nm, and positively-charged 190nm NPs) with blood components, namely red blood cells (RBC) and plasma proteins, with the view to inspect their hemocompatibility. The NPs, preliminarily characterized by XRD, FTIR and DLS, showed low hemolysis ratio (typically lower than 5%) illustrating the high compatibility of such NPs with respect to RBC, even at high concentration (up to 10mg/ml). The presence of glucose as water-soluble matrix for freeze-dried and re-dispersed colloids led to slightly increased hemolysis as compared to glucose-free formulations. NPs/plasma protein interaction was then followed, via non-specific protein fluorescence quenching assays, by contact with whole human blood plasma. The amount of plasma proteins in interaction with the NPs was evaluated experimentally, and the data were fitted with the Hill plot and Stern-Volmer models. In all cases, binding constants of the order of 10(1)-10(2) were found. These values, significantly lower than those reported for other types of nanoparticles or molecular interactions, illustrate the fairly inert character of these colloidal NPs with respect to plasma proteins, which is desirable for circulating injectable suspensions. Results were discussed in relation with particle surface charge and mean particle hydrodynamic diameter (HD). On the basis of these hemocompatibility data, this study significantly complements previous results relative to the development and nontoxicity of biomimetic-apatite-based colloids stabilized by non-drug biocompatible organic molecules, intended for use in nanomedicine.

Preparation of laponite bioceramics for potential bone tissue engineering applications

We report a facile approach to preparing laponite (LAP) bioceramics via sintering LAP powder compacts for bone tissue engineering applications. The sintering behavior and mechanical properties of LAP compacts under different temperatures, heating rates, and soaking times were investigated. We show that LAP bioceramic with a smooth and porous surface can be formed at 800°C with a heating rate of 5°C/h for 6 h under air. The formed LAP bioceramic was systematically characterized via different methods. Our results reveal that the LAP bioceramic possesses an excellent surface hydrophilicity and serum absorption capacity, and good cytocompatibility and hemocompatibility as demonstrated by resazurin reduction assay of rat mesenchymal stem cells (rMSCs) and hemolytic assay of pig red blood cells, respectively. The potential bone tissue engineering applicability of LAP bioceramic was explored by studying the surface mineralization behavior via soaking in simulated body fluid (SBF), as well as the surface cellular response of rMSCs. Our results suggest that LAP bioceramic is able to induce hydroxyapatite deposition on its surface when soaked in SBF and rMSCs can proliferate well on the LAP bioceramic surface. Most strikingly, alkaline phosphatase activity together with alizarin red staining results reveal that the produced LAP bioceramic is able to induce osteoblast differentiation of rMSCs in growth medium without any inducing factors. Finally, in vivo animal implantation, acute systemic toxicity test and hematoxylin and eosin (H&E)-staining data demonstrate that the prepared LAP bioceramic displays an excellent biosafety and is able to heal the bone defect. Findings from this study suggest that the developed LAP bioceramic holds a great promise for treating bone defects in bone tissue engineering.

Physicochemical, antimicrobial and antioxidant properties of chitosan films incorporated with carvacrol

Chitosan films (CF) with carvacrol (CAR) [0.5%, 1.0% and 1.5% v/v] were prepared by the emulsion method. The retained CAR, water solubility, water vapor permeability (WVP), optical, mechanical properties, antibacterial and antioxidant capacity of films were analyzed. The results indicate that the retention of CAR in the CF was ≈50%. The incorporation of CAR to CF decreased the water solubility, the WVP, the yellowing and transparency and the tensile strength, but increased the stiffness. Microcapsules with diameters of 2 to 7 µm were found on the surface CF-CAR. The CF-CAR with highest CAR concentrations showed antibacterial activity against S. typhimurium and E. coli O157:H7. The CF-CAR had higher antioxidant capacity and an increased protective effect against oxidation of erythrocytes in different grades. These results suggest potential applications of CF-CAR as active packaging to preserve food products.

Blood contact properties of ascorbyl chitosan

Ascorbyl chitosan was synthesized by heating chitosan with ascorbic acid in isopropanol. The products were characterized by FTIR and C-13 NMR spectroscopies, SEM, and elemental analysis. Blood contact properties of ascorbyl chitosans were evaluated. The ascorbyl chitosans demonstrated to have increased lipid-lowering activity in comparison to chitosan alone upon contact with human blood serum in in vitro conditions. Furthermore, the total cholesterol/HDL ratio was improved towards the desirable ideal values after three hours contact with ascorbyl chitosan samples. The lipid-lowering activity increased with ascorbyl substitution. The inherent nonspecific adsorption capability of chitosan due to its chelating power with several different functional groups was exhibited by ascorbyl chitosans as well. This behavior was exemplified in a simultaneous decrease in the total iron values of the volunteers together with lower lipid levels. Furthermore, ascorbyl chitosans were observed to have less hemocompatibility but increased anticoagulant activity when compared to chitosan alone. Additional in vivo studies are necessary to support these results and to investigate further the advantages and disadvantages of these materials to prove their safety prior to clinical applications.

Rapidly stopping hemorrhage by enhancing blood clotting at an opened wound using chitosan/polylactic acid/polycaprolactone wound dressing device

Doxycycline and monosodium glutamate (MSG) loaded chitosan (CHI)/polylactic acid (PLA)/polycaprolactone (PCL) blend film was studied as a model device to deliver drug to targeted human organ which in this case was the skin with opened wound. The CHI/PLA/PCL blend film containing 60 % CHI, 28 % PLA, and 12 % PCL exhibited the good properties for making the dressing device. It was observed that doxycycline/MSG loaded CHI/PLA/PCL blend film could rapidly deliver both doxycycline and MSG at the high release percentage approaching 100 % loaded. MSG accelerated blood clotting and fibrin formation; thus, it exhibited the good hemostatic activity. The antibacterial activity of doxycycline loaded CHI/PLA/PCL blend film against Staphylococcus aureus and Escherichia coli as model bacteria was investigated. Doxycycline release played the crucial role in bacterial inhibition as observed from the lowest bacterial cell dry weight observed when compared with the control bacterial culture or the bacterial cultures with the presence of other films studied.

Blood compatibility of polymers derived from natural materials

Several polymers derived from natural materials are effective for tissue engineering or drug delivery applications, due to specific properties, such as biocompatibility, biodegradability, and structural activity. Their blood compatibility needs to be carefully evaluated to avoid thrombosis and other material-related adverse events in the hematic environment. We compared the surface properties and blood compatibility of protein and polysaccharide polymers, including fibroin, gelatin, and chitosan. Both fibroin and chitosan showed good hemocompatibility, with low platelet adhesion and spreading. Chitosan induced strong interactions with plasma proteins, especially with albumin. It was hypothesized that surface passivation by albumin inhibited the adsorption of other procoagulant and proadhesive proteins on chitosan and fibroin films, which limited platelet spreading. However, the significant and rapid polymer swelling encouraged protein entrapment within the soft, gelatin films, inducing higher platelet adhesion and activation. Thrombin generation assay confirmed the higher blood compatibility of chitosan and fibroin with regard to clotting.

Positive charge of chitosan retards blood coagulation on chitosan films

In this study, a series of chitosan films with different protonation degrees were prepared by deacidification with NaOH aqueous or ethanol solutions. The films were then used as a model to investigate the effects of the positive charge of chitosan on blood coagulation. The results showed that the positive charge of chitosan acted as a double-edged sword, in that it promoted erythrocyte adhesion, fibrinogen adsorption, and platelet adhesion and activation, but inhibited activation of the contact system. In contrast to prevailing views, we found that the positive charge of chitosan retarded thrombin generation and blood coagulation on these films. At least two reasons were responsible for this phenomenon. First, the positive charge inhibited the contact activation, and second, the positive charge could not significantly promote the activation of non-adherent platelets in the bulk phase during the early stage of coagulation. The present findings improve our understanding of the events leading to blood coagulation on chitosan films, which will be useful for the future development of novel chitosan-based hemostatic devices.

Preparation of chitosan films using different neutralizing solutions to improve endothelial cell compatibility

The development of chitosan-based constructs for application in large-size defects or highly vascularized tissues is still a challenging issue. The poor endothelial cell compatibility of chitosan hinders the colonization of vascular endothelial cells in the chitosan-based constructs, and retards the establishment of a functional microvascular network following implantation. The aim of the present study is to prepare chitosan films with different neutralization methods to improve their endothelial cell compatibility. Chitosan salt films were neutralized with either sodium hydroxide (NaOH) aqueous solution, NaOH ethanol solution, or ethanol solution without NaOH. The physicochemical properties and endothelial cell compatibility of the chitosan films were investigated. Results indicated that neutralization with different solutions affected the surface chemistry, swelling ratio, crystalline conformation, nanotopography, and mechanical properties of the chitosan films. The NaOH ethanol solution-neutralized chitosan film (Chi-NaOH/EtOH film) displayed a nanofiber-dominant surface, while the NaOH aqueous solution-neutralized film (Chi-NaOH/H(2)O film) and the ethanol solution-neutralized film (Chi-EtOH film) displayed nanoparticle-dominant surfaces. Moreover, the Chi-NaOH/EtOH films exhibited a higher stiffness as compared to the Chi-NaOH/H(2)O and Chi-EtOH films. Endothelial cell compatibility of the chitosan films was evaluated with a human microvascular endothelial cell line, HMEC-1. Compared with the Chi-NaOH/H(2)O and Chi-EtOH films, HMECs cultured on the Chi-NaOH/EtOH films fully spread and exhibited significantly higher levels of adhesion and proliferation, with retention of the endothelial phenotype and function. Our findings suggest that the surface nanotopography and mechanical properties contribute to determining the endothelial cell compatibility of chitosan films. The nature of the neutralizing solutions can affect the physicochemical properties and endothelial cell compatibility of chitosan films. Therefore, selection of suitable neutralization methods is highly important for the application of chitosan in tissue engineering.

Biocompatibility study of theophylline/chitosan/beta-cyclodextrin microspheres as pulmonary delivery carriers

To evaluate the biocompatibility of the theophylline/chitosan/beta-cyclodextrin microspheres, which has a potential application in pulmonary delivery system. The detection of LDH and protein in BALF was examined acute cell toxicity, hemolysis test was carried out to estimate blood toxicity; Micronucleus Test was reckoned to identify genotoxicity, MTT assay was used to evaluate in vitro cytotoxicity, and muscle implantation investigated the tissue biocompatibility. The results demonstrated that the total contents of protein and LDH in BALF were not significantly different from that of normal group. The experiments showed that the cytotoxicity was depended on the concentration and had no cytoxicity at low concentration and no hemolysis activity. The micronucleus frequency of MS B was 0.99 per thousand, which showed no genotoxic effects either. The results of implantation showed that the microspheres had no effect on hemoglobin and no toxicity in the liver and kidney. The inflammations of muscle tissue were not significantly different from that of operative suture, therefore, the MS B possess high good biocompatibility and can be applied in pulmonary sustained release systems.

Investigation of polymeric amphiphilic nanoparticles as antitumor drug carriers

In this paper, polymeric amphiphilic nanoparticles based on oleoyl-chitosan (OCH) with different degrees of substitution (DS, 5%, 11% and 27%) were prepared by Oil/Water emulsification method. Mean diameters of the nanoparticles were 327.4 nm, 255.3 nm and 192.6 nm, respectively. Doxorubicin (DOX) was efficiently loaded into OCH nanoparticles and provided a sustained released after a burst release in PBS. These nanoparticles showed no cytotoxicity to mouse embryo fibroblasts (MEF) and low hemolysis rates (<5%). The results of SDS-PAGE indicated that bovine calf serum (BCS) adsorption on OCH nanoparticles was inhibited by smaller particle size. Cellular uptake was evaluated by incubating fluorescence labeled OCH nanoparticles with human lung carcinoma cells (A549) and mouse macrophages (RAW264.7). Cellular uptake of OCH nanoparticles was time--and concentration--dependent. Finding the appropriate incubation time and concentration of OCH nanoparticles used as drug carriers might decrease phagocytic uptake, increase cancer cell uptake and ultimately improve therapeutic efficiency of antitumor therapeutic agents.