[A Noval Method for Producing Antibacterial Wound Dressing by Using Fused Deposition Molding with Post-3D-printed Process].

Using three-dimensional printing to produce antibacterial wound dressing is a new topic that will change the production style of wound dressing industry. Combining with post-3D-printed process, a desktop fused deposition molding equipment can be used to produce wound dressing containing polyvinyl alcohol, alginate and chitosan. The wound dressing produced by FDM has good aspects of absorbency, moisture vapour transmission rate and mechanical property. After loaded with antibacterial agent iodine and silver nano particle, the antibacterial activity rate increases to 99% and it is suitable to use as antibacterial wound dressing. This method affects the production of wound dressing to a more cost-effective way, and provides a possible individualized treatment for patient in the future.

[Development of Thrombus Aspiration Catheter].

Coronary disease is one of the highest mortality diseases in the world,and interventional therapy has been the best treatment choice for its low risks,high efficiency,less wound and rapid recovery after the operation.Thrombus aspiration catheter is one of the most important equipment in the interventional therapy instrument of coronary disease.This paper is based on the demand of clinical and market,designed and manufactured aspirated catheter for the treatment of coronary thrombosis.Through the performance comparison of the material,confirmed the main material quality of thrombus aspiration catheter and its organization.We also made the appraisement for the function of the material and the main performance of the thrombus aspiration catheter.The experiment turned out that our catheter performance is stable and also with highly reliable,which is absolutely fit for the using requirements of the clinical.

[Utilization of three-dimensional printing technology for repairing skin tissue].

Three-dimensional (3D) printing is a low-cost, high-efficiency production method, which can reduce the current cost and increase the profitability of skin repair material industry nowadays, and develop products with better performance. The 3D printing technology commonly used in the preparation of skin repair materials includes fused deposition molding technology and 3D bioprinting technology. Fused deposition molding technology has the advantages of simple and light equipment, but insufficient material selection. 3D bioprinting technology has more materials to choose from, but the equipment is cumbersome and expensive. In recent years, research on both technologies has focused on the development and application of materials. This article details the principles of fused deposition modeling and 3D bioprinting, research advances in wound dressings and tissue engineering skin production, and future developments in 3D printing on skin tissue repair, including cosmetic restoration and biomimetic tissue engineering. Also, this review prospects the development of 3D printing technology in skin tissue repairment.

[Utilization of Three-dimensional Printing Technology for Manufacture of Artificial Organs].

In this article, we introduce the principle, describe the utilization and discuss the future development of three-dimensional printing technology for manufacturing artificial organs.

[Surface-enhanced Raman spectra analysis of trace degradation products from goat horn].

Nano-silver colloid was synthesized by using microwave method on the mixtures of sodium citrate solution and silver nitrate solution. The method has advantages of fast heating speed, uniform temperature distribution and easily controlled reaction conditions. The sizes and size distributions of the silver particles were characterized by means of quasi-elastic laser scattering (QLS). The average particles size was (53.27 +/- 2.65) nm and the size of the particles was mainly distributed around 56 nm. Surface-enhanced Raman spectra of the degradation products from goat horn were obtained with silver colloid as active substrate. It was observed that the Raman signal of SERS was enhanced significantly compared with that of regular Raman spectrum, especially at the Raman bands of 659, 830, 850, 929, 999, 1 028, 1 280, 1 439 and 1 599 cm(-1) which reflect the biochemical components in degradation products. The characteristic Raman bands of degradation products from goat horn were preliminary assigned. The assignments showed that the main constituents of the degradation products from goat horn were amino acids and polypeptides. It was for the first time that Surface-enhanced Raman spectroscopy was used to detect trace degradation products from the horns. Raman signal enhancement can be obtained with high sensitivity for the trace concentrations as low as ppm level. It is concluded that surface-enhanced Raman spectroscopy can provide a fast, direct and precise detecting method for the detection of trace degradation solution from horns.

[Mechanical properties and biological evaluation of buffalo horn material].

Mechanical properties and biological evaluation of buffalo horn material were examined in this study. The effects of sampling position of buffalo horn on mechanical properties were investigated with uniaxial tension and micron indentation tests. Meanwhile, the variation of element contents in different parts of buffalo horn was determined with elemental analysis, and the microstructure of the horn was measured with scanning electron microscopy. In addition, biological evaluation of buffalo horn was studied with hemolytic test, erythrocyte morphology, platelet and erythrocyte count, and implantation into mouse. Results showed that the buffalo horn had good mechanical properties and mechanical characteristic values of it gradually increased along with the growth direction of the horn, which may be closely related to its microstructure and element content of C, N, and S in different parts of the buffalo horn. On the other hand, because the buffalo horn does not have toxicity, it therefore does not cause hemolysis of erythrocyte and has a good affinity with it. Buffalo horn has good histocompatibility but meanwhile it may induce the platelet adhesion and aggregation. Even so, it does not continue to rise to induce a large number of platelet to aggregate with resulting blood clotting. Therefore, the buffalo horn material has been proved to possess good blood compatibility according to the preliminary evaluation.

Preparation and evaluation of stingray skin collagen/oyster osteoinductive composite scaffolds.

The regeneration of bone defects is a major challenge for clinical orthopaedics. Herein, we designed and prepared a new type of bioactive material, using stingray skin collagen and oyster shell powder (OSP) as raw materials. A stingray skin collagen/oyster osteoinductive composite scaffold (Col-OSP) was prepared for the first time by genipin cross-linking, pore-forming and freeze-drying methods. These scaffolds were characterized by ATR-FTIR, SEM, compression, swelling, cell proliferation, cell adhesion, alkaline phosphatase activity, alizarin red staining and RT-PCR etc. The Col-OSP scaffold had an interconnected three-dimensional porous structure, and the mechanical properties of the Col-OSP composite scaffold were enhanced compared with Col, combining with the appropriate swelling rate and degradation rate, the scaffold was more in line with the requirements of bone tissue engineering scaffolds. The Col-OSP scaffold was non-toxic, promoted the proliferation, adhesion, and differentiation of MC3T3-E1 cells, and stimulated the osteogenesis-related genes expressions of osteocalcin (OCN), collagen type I (COL-I) and RUNX2 of MC3T3-E1 cells.

In-situ formable dextran/chitosan-based hydrogels functionalized with collagen and EGF for diabetic wounds healing.

Delayed or non-healing skin wounds causing gangrene or even amputation, greatly threats diabetic patients lives. Herein, a bioactive, in-situ formable hydrogel based wound dressing was designed through simple Schiff base reaction. Oxidized dextran (OD) and carboxyethyl chitosan (CEC) were crosslinked together and applied as the main porous framework of hydrogel. To improve the mechanical strength and biocompatibility, collagen (Col) and EGF (Epidermal Growth Factor) were introduced into OD-CEC precursors: (1) after addition of only Col, the mechanical strength of hydrogels was improved by participating the functional -NH2 group of Col into the crosslinking process. Moreover, swelling ratio was as high as 750% on 3%OD-3%CEC-Col (water retention rate was 65 wt% after 7 days). (2) Once we introduced both Col and EGF into the OD-CEC hydrogel, the proliferation of mouse embryonic fibroblast (NIH 3T3) cells was promoted using 3%OD-3%CEC-Col/EGF, an accelerated wound healing was observed with 86% wound closure after only 14 operative days. Hematoxylin and eosin (H&E) staining and Masson staining indicated the synergy of Col and EGF might promote new tissue's formation, well collagen distributions and thus accelerate skin regeneration, presenting great potentials in wound healing of diabetic patients.

A synergy between dopamine and electrostatically bound bactericide in a poly (vinyl alcohol) hybrid hydrogel for treating infected wounds.

Antibacterial hydrogels have emerged as viable options for battling infections associated with impaired wound healing. It is challenging in developing antibacterial hydrogels that have sustained and stable bactericidal activity while avoiding the use of any agents that may adversely affect safety. In view of this concern, a multi-functional polyvinyl alcohol (PVA)/sodium alginate-dopamine (SA-DA) hydrogel matrix-based wound dressing embedding with bis-quaternary triphenyl-phosphonium salt (BTPP+), that would present long-term intrinsic antimicrobial properties was developed using freeze-thawing (F-T) method herein. DA endows the hydrogel with efficient bacteria capture ability and subsequently the captured bacterial pathogens were in situ killed by electrostatically bound BTPP+, and hence significantly augmented the antibacterial efficacy. Furthermore, DA, co-operating with BTPP+ could promote erythrocyte and platelet aggregation on hydrogels, which ensures hydrogels with improved hemostasis capacity. Thus, this investigation provides a feasible simple avenue for development of long-term intrinsic antimicrobial hydrogel dressings with efficient hemostasis efficacy for infected wounds.

Fabrication of a multi-level drug release platform with liposomes, chitooligosaccharides, phospholipids and injectable chitosan hydrogel to enhance anti-tumor effectiveness.

Some anti-cancer drugs have poor solubility and availability, and are easily eliminated by rapid metabolism in vivo. To fix the drugs at the administration site and delay their release, a release platform with multi-level and multi-function was designed. The results showed that the curcumin (Cur) loaded liposomes (Cur@Lip) were coated sequentially with positive Chitooligosaccharides (Cur@Lip-Cos) and negative phospholipids (Cur@Lip-Cos-PC), to enhance water solubility, encapsulation efficiency, and delayed the release of the Cur, stability and cell intake of the liposomes, and the bioactivity of the system. The Cur@Lip-Cos could significantly enhance the inhibitory effect of MCF-7, better than the Cur@Lip-Cos-PC. The Lips were then fixed in an injectable thiolated chitosan hydrogel for local immobilization and sustained release which can effectively delay the release of Cur to inhibit MCF-7 growth. In summary, the innovative and biomimetic liposomal hydrogels are expected to provide more ideas for the design of drug carriers.

Immobilization of type-I collagen and basic fibroblast growth factor (bFGF) onto poly (HEMA-co-MMA) hydrogel surface and its cytotoxicity study.

Type-I collagen and bFGF were immobilized onto the surface of poly (HEMA-co-MMA) hydrogel by grafting and coating methods to improve its cytotoxicity. The multi-layered structure of the biocompatible layer was confirmed by FTIR, AFM and static water contact angles. The layers were stable in body-like environment (pH 7.4). Human skin fibroblast cells (HSFC) were seeded onto Col/bFGF-poly (HEMA-co-MMA), Col-poly (HEMA-co-MMA) and poly (HEMA-co-MMA) films for 1, 3 and 5 day. MTT assay was performed to evaluate the extraction toxicity of the materials. Results showed that the cell attachment, proliferation and differentiation on Col/bFGF-poly (HEMA-co-MMA) film were higher than those of the control group, which indicated the improvement of cell-material interaction. The extraction toxicity of the modified materials was also lower than that of the unmodified group. The protein and bFGF immobilized poly (HEMA-co-MMA) hydrogel might hold great promise to be a biocompatible material.

Secondary cancer risk after radiation therapy for breast cancer with different radiotherapy techniques.

The aim of this study was to estimate the radiation-related secondary cancer risks in organs during the treatment of breast cancer with different radiotherapy techniques, such as three-dimensional conformal radiotherapy (3D-CRT), intensity modulated radiotherapy (IMRT), and volumetric modulated arc therapy (VMAT). The treatment plans for 26 patients with breast cancer who received whole-breast irradiation at a dose of 50 Gy included tangential field 3D-CRT with hard-wedges (W-TF), tangential field IMRT (2F-IMRT), multiple field IMRT (6F-IMRT), and double partial arcs (VMAT). Patients were divided into three groups according to the distance between the contralateral breast (CB) and the body of the sternum. Setup error was simulated by moving the isocenter, and the dose distribution was then recalculated without changing the field fluency distribution. Based on the linear-exponential, the plateau, and the full mechanistic dose-response models, the organ equivalent dose and excess absolute risk were calculated from dose-volume histograms to estimate the secondary cancer risks in organs. Compared with 3D-CRT, IMRT and VMAT showed excellent results regarding tumor conformity and homogeneity; however, the low dose volume to organs was considerably higher in 6F-IMRT and VMAT. Secondary cancer risks for 2F-IMRT were comparable or slightly lower than for W-TF, but considerably lower than for 6F-IMRT or VMAT. After setup error simulation, there was a small increase in secondary cancer risk for 2F-IMRT and an increase of 159% and 318% for 6F-IMRT and VMAT, respectively, compared with W-TF. Although these results were obtained in most patients, they did not necessarily apply to every individual. The secondary cancer risks in the CB decreased significantly in correlation with increased distance for all alternative techniques, although they were higher in VMAT and lower in 2F-IMRT regardless of the distance. After setup error simulation, the increased changes in secondary cancer risks in the CB were comparable between 2F-IMRT, 6F-IMRT, and VMAT, suggesting that the secondary cancer risks in the CB mainly depend on radiotherapy techniques and distance, although the effect of setup error cannot be ignored. In the contralateral lung (CL), the secondary cancer risks were almost independent from distance and depended mainly on radiotherapy techniques; they were rarely affected by setup error. VMAT was associated with a higher secondary cancer risk in the CL. For the ipsilateral lung (IL), the secondary cancer risks were higher than those in other organs because the IL receives high doses to achieve tumor control, and they were relatively lower in VMAT. This warrants special consideration when estimating the secondary cancer risk to the IL. The study results suggested that the optimal radiotherapy method for breast cancer should be determined on an individual basis and according to the balance between secondary cancer risks related to anatomic diversity and setup error, which can prevent blind selection of techniques.

PEGylated Bis-Quaternary Triphenyl-Phosphonium Tosylate Allows for Balanced Antibacterial Activity and Cytotoxicity.

Quaternary triphenylphosphonium compounds (TPP+) have been widely recognized as an important antimicrobial because of their fast antimicrobial speed and broad antimicrobial spectrum. However, small-molecule TPP+ compounds have the defects of toxicity, which is the key factor that limits their practical applications. Here, two mono- and one bis-quaternary phosphonium tosylate compounds with different lengths of oligo(ethylene glycol) (OEG) chains and TPP+ as the active moiety were synthesized. Bis-TPP+ have a short OEG chain coupling two TPP+ at both ends, while mono-TPP+ attaches the OEG chain at one end in one molecule. In vitro antibacterial activities were evaluated against both Gram-positive as well as Gram-negative bacteria in terms of the inhibition zone (ZOI) and minimum inhibitory concentration (MIC). To investigate the antibacterial mechanism, ß-galactosidase activity was monitored for measuring the degree of membrane permeability correlated to the abilities to disrupt the membranes of bacteria. Moreover, their structure-antibacterial activity and structure-cytotoxicity relationships were further analyzed. The results indicated that bis-TPP+ synthesized can reach the sterilization rate 90% or more against Escherichia coli and Staphylococcus aureus at MICs of 3.1 and 1.5 mg/mL, respectively, and meanwhile, the cell proliferation can reach more than 80%. This paper represents an excellent approach for development of bis-TPP+ bactericidal molecules that would achieve an optimal balance between antimicrobial activity and cytotoxicity.

Histatin1-modified thiolated chitosan hydrogels enhance wound healing by accelerating cell adhesion, migration and angiogenesis.

It is urgently needed for effective treatments of extensive skin loss, wherein lack of angiogenesis is a major obstacle. In this study, we present a thermosensitive thiolated chitosan (CSSH) hydrogel conjugated with Histatin1 (Hst1) as a wound dressing to study its efficacy in enhancing the cell adhesion, spreading, migration, and angiogenesis. The composite hydrogels with gelation time of 5-7 min, showed a prolonged release of Hst1. Cell culture indicated that the adhesion, spreading, migration and tubule formation of HUVECs were promoted, especially for the Hst1-H group. The in vivo healing evaluation showed that the rate of recovery in Hst1-H group was increased to 84% at day 7, and the CD31 positive cells, vascular endothelial growth factor (VEGF) positive cells and aligned collagen fibers were significantly more than the controlled groups. Therefore, CSSH/Hst1 hydrogel is a promising candidate for wound healing by accelerating cell adhesion, migration and angiogenesis.

Injectable and In Situ-Formable Thiolated Chitosan-Coated Liposomal Hydrogels as Curcumin Carriers for Prevention of In Vivo Breast Cancer Recurrence.

To improve water solubility and bioavailability, curcumin (Cur) was encapsulated by liposomes (Cur-Lip), which was further coated with thiolated chitosan (CSSH) to form liposomal hydrogels (CSSH/Cur-Lip gel). The hydrogels were thermosensitive with in situ injectable performance, which were fluidic at room temperature and gelled quickly at 37 °C. The cumulative release ratio of the 200 µM CSSH/Cur-Lip gel was 31.57 ± 1.34% at 12 h, which could effectively delay the release of curcumin. Worthily, the resilient hydrogels were compressive even after five cycles of compression. The cytotoxicity test indicated that the liposomal hydrogels had good cytocompatibility, but after encapsulation of curcumin, MCF-7 cells were suppressed and killed dramatically after 72 h. The in vivo breast cancer recurrence experiment showed that the CSSH/Cur-Lip gel inhibited breast cancer recurrence after tumors were resected, and the tissue of defect in the CSSH/Cur-Lip gel group was repaired. The results showed that the drug-loaded liposomal hydrogels can deliver curcumin continuously and exerted an excellent tumoricidal effect in vitro and in vivo. The injectable, in situ-formable, and thermosensitive CSSH/Cur-Lip gel can be designed as a promising novel drug delivery vehicle to be used as carriers for local accurate and sustained drug delivery to minimize burst release and as tissue engineering scaffolds for tissue regeneration after tumor resection.

The effects of motif net charge and amphiphilicity on the self-assembly of functionally designer RADA16-I peptides.

RADA16-I (Ac-(RADA)4-CONH2) is a widely investigated self-assembling peptide (SAP) in the biomedical field. It can undergo ordered self-assembly to form stable secondary structures, thereby further forming a nanofiber hydrogel. The modification of RADA16-I with functional peptide motifs has become a popular research topic. Researchers aim to exhibit particular biomedical signaling, and subsequently, further expand its applications. However, only a few fundamental reports are available on the influences of the peptide motifs on self-assembly mechanisms of designer functional RADA16-I SAPs. In this study, we designed RGD-modified RADA16-I SAPs with a series of net charges and amphiphilicities. The assembly/reassembly of these functionally designer SAPs was thoroughly studied using Raman spectroscopy, CD spectroscopy, and AFM. The nanofiber morphology and the secondary structure largely depended on the balance between the hydrophobic effects versus like-charge repulsions of the motifs, which should be to the focus in order to achieve a tailored nanostructure. Our study would contribute insight into considerations for sophisticated design of SAPs for biomedical applications.

Preparation and evaluation of chitosan/alginate porous microspheres/Bletilla striata polysaccharide composite hemostatic sponges.

We prepared a novel hemostatic material using chitosan (CS), alginate, and Bletilla striata, which showed good biocompatibility and hemostatic properties. Alginate-calcium porous microspheres (Alg) were prepared by emulsification/cross-linking methods, and Bletilla striata polysaccharide (Bsp) was extracted from the tubers by water extraction and alcohol precipitation. To improve the water absorption and accelerate the blood coagulation, Alg and Bsp were mixed with chitosan solution to form CS/Alg and CS/Alg/Bsp composite sponges by lyophilization. Based on SEM images, the microspheres exhibited good spherical shape, possessed many pores on the surface, and were well dispersed in the CS/Alg5 and CS/Alg10 composite sponges. The CS/Alg10 composite sponges showed higher water absorption and porosity. In addition, the cytotoxicity assay and hemostatic property of the CS/Alg and CS/Alg/Bsp composite sponges were tested by CCK-8 assay, in vitro blood clotting, red blood cell (RBC) adhesion, and rabbit ear artery bleeding. These ternary composite sponges could be used as potential novel hemostatic materials in surgical treatment.

Mechanical and biological properties of oxidized horn keratin.

The goal of this study was to investigate the mechanical and biological properties of oxidized keratin materials, which were obtained by using buffalo horns to oxidize. It could provide a way to evaluate their potential for clinical translatability. The characterization on their composition, mechanical properties, and biological responses was performed. It is found that the oxidation process could lead the disulfide bond to break down and then to form sulfonic acid, or even make partial peptide chain to be fragment for the new modification of amino acid. Hence the oxidized horn keratins have lower thermal stability and hydrolytic stability in comparison with horn keratin, but the degradation products of oxidized horn keratins have no significant difference. In addition, the mechanical properties of oxidized horn keratins are poorer than that of horn keratin, but the oxidized horn keratins still have disulfide bonds to form a three-dimensional structure, which benefits for their mechanical properties. The fracture toughness of oxidized horn keratins increases with the increase in the degree of oxidation. After oxidation, the oxidized horn keratins have lower cytotoxicity and lower hemolysis ratio. Moreover, when the oxidized horn keratins, as well as different concentration of degradation products of oxidized horn keratins, are directly in contact with platelet-rich plasma, platelets are not activated. It suggests that the oxidized horn keratins have good hemocompatibility, without triggering blood thrombosis. The implantation experiment in vivo also demonstrates that the oxidized horn keratins are compatible with the tissue, because there are minimal fibrous capsule and less of infiltration of host cells, without causing serious inflammation. In summary, the oxidized horn keratins can act as implanted biomaterial devices that are directly in contact with blood and tissue.

Coaxial electrospun zein nanofibrous membrane for sustained release.

Zein nanofibrous membranes for sustained release have been prepared by coaxial electrospinning. Core-sheath structure has been successfully fabricated using zein as both the core and sheath component. Impact of solvent and solution concentration on the morphology of the resulting fibers was investigated. Allyltriphenylphosphonium bromide was used as a model drug to test the sustained release effect. The sustained release profile and the antimicrobial activity of the resulting membranes were investigated and compared with that of the single fluid electrospinning of zein/drug blended membrane. The ratio of the inner and outer feeding rates was found to influence the encapsulation of drugs, and in turn affect the sustained release effect of the resulting membranes. The coaxial electrospinning membrane can remarkably suppress the initial burst release of drugs by giving a releasing amount of 15% in the first 1 h when the inner/outer ratio was larger than 1:2. This drug-loaded zein membrane with preferable sustained release effect can be applied in many fields such as wound healing and packaging sector.

Microstructure and mechanical properties of horns derived from three domestic bovines.

The microstructure and mechanical properties of horns derived from three domestic bovines (buffalo, cattle and sheep) were examined. The effects of water content, sampling position and orientation of three bovid horns on mechanical properties were systematically investigated by uniaxial tension and micron indentation tests. Meanwhile, the material composition and metal element contents were determined by Raman spectroscopy and elemental analysis respectively, and the microstructures of the horns were measured by scanning electron microscopy (SEM). Results show that the mechanical properties of horns have negative correlation with water contents and depend on sampling position and orientation. The spatial variations of the mechanical properties in horns are attributed to the different keratinization degrees in the proximal, middle and distal parts. And the mechanical properties of horns in the longitudinal direction are better than those in transverse. Among the three kinds of horns, the mechanical properties of buffalo horn are the best, followed by cattle horn, and those in sheep horn are the worst. This is due to the differences in material composition, metal element, and the microstructures of the horns. But the mechanical properties of buffalo horns are not dependent on the source of the buffalo. Therefore, regular engineered buffalo keratinous materials with standard mechanical properties can be obtained from different buffalo horns by using proper preparation methods.