Engineering design of asymmetric halloysite/chitosan/collagen sponge with hydrophobic coating for high-performance hemostasis dressing

Uncontrolled massive hemorrhage is a crucial cause of death, and developing efficient hemostatic materials are of great medical importance. Herein, we prepared a halloysite-chitosan-collagen composite sponge by directional freeze-drying method and coating the sponge by hydrophobic polydimethylsiloxane coating for rapid and effective hemostasis. The aligned channel structure of the sponge with a pore size of ~30 μm was beneficial for the transport of blood. Morphology and spectrum results suggested that chitosan and collagen are capable of adsorbing on the outer surface of HNTs due to the hydrogen bonding and electrostatic attractions. The directional freeze-dried sponge absorbed the majority of the blood within 10 s, and that process essentially completed in 30 s, which are faster than its non-directional counterpart. The composite sponges exhibited high antibacterial properties towards E. coli and S. aureus, and they are non-cytotoxic towards mouse fibroblasts and have high hemocompatibility. The hemostatic dressing avoided unnecessary blood loss because of excessive blood absorption. In vivo experiments of rats also confirmed the ability of the asymmetric sponges to rapidly clot and reduce reducing blood loss. This work developed a high-performance and hemostatic dressing by material design and processing technique, which shows a promising application in wound healing.

Biocompatible Carboxymethyl Chitosan/GO-Based Sponge to Improve the Efficiency of Hemostasis and Wound Healing

Sponges with highly absorptive properties have been widely used in emergency hemostasis. Graphene oxide (GO) has been extensively investigated in biomedical applications and is a promising candidate for hemostatic sponges. However, GO has been demonstrated to have adverse effects on the human body. To overcome this problem, a hemostatic sponge based on modified GO and carboxymethyl chitosan (CMCS) is successfully prepared, which has excellent water absorption ability and mechanical strength. Importantly, hemostasis assays showed that the composite sponge exhibited high hemostatic efficiency, and the possible hemostatic mechanism is also discussed in this study. Moreover, the results of in vitro antibacterial tests reveal that the composite sponge also presents strong antimicrobial effects against Staphylococcus aureus and Escherichia coli. Significantly, the composited sponge used as hemostatic dressing can effectively promote cell proliferation, achieving a wound closure rate of 95% on day 12. Such a graphene-based sponge with multiple advantageous features would hold broad prospects in the hemostatic field.

Conjugate Electrospun 3D Gelatin Nanofiber Sponge for Rapid Hemostasis

Developing an excellent hemostatic material with good biocompatibility and high blood absorption capacity for rapid hemostasis of deep non-compressible hemorrhage remains a significant challenge. Herein, a novel conjugate electrospinning strategy to prepare an ultralight 3D gelatin sponge consisting of continuous interconnected nanofibers. This unique fluffy nanofiber structure endows the sponge with low density, high surface area, compressibility, and ultrastrong liquid absorption capacity. In vitro assessments show the gelatin nanofiber sponge has good cytocompatibility, high cell permeability, and low hemolysis ratio. The rat subcutaneous implantation studies demonstrate good biocompatibility and biodegradability of gelatin nanofiber sponge. Gelatin nanofiber sponge aggregates and activates platelets in large quantities to accelerate the formation of platelet embolism, and simultaneously escalates other extrinsic and intrinsic coagulation pathways, which collectively contribute to its superior hemostatic capacity. In vivo studies on an ear artery injury model and a liver trauma model of rabbits demonstrate that the gelatin nanofiber sponge rapidly induce stable blood clots with least blood loss compared to gelatin nanofiber membrane, medical gauze, and commercial gelatin hemostatic sponge. Hence, the gelatin nanofiber sponge holds great potential as an absorbable hemostatic agent for rapid hemostasis.

Haemostatic materials for wound healing applications

Wounds are one of the most common health issues, and the cost of wound care and healing has continued to increase over the past decade. The first step in wound healing is haemostasis, and the development of haemostatic materials that aid wound healing has accelerated in the past 5 years. Numerous haemostatic materials have been fabricated, composed of different active components (including natural polymers, synthetic polymers, silicon-based materials and metal-containing materials) and in various forms (including sponges, hydrogels, nanofibres and particles). In this Review, we provide an overview of haemostatic materials in wound healing, focusing on their chemical design and operation. We describe the physiological process of haemostasis to elucidate the principles that underpin the design of haemostatic wound dressings. We also highlight the advantages and limitations of the different active components and forms of haemostatic materials. The main challenges and future directions in the development of haemostatic materials for wound healing are proposed.

Cellulose nanocrystals-based materials as hemostatic agents for wound dressings: a review

Wound dressings are devices used to stop bleeding and provide appropriate environmental conditions to accelerate wound healing. The effectiveness of wound dressing materials can be crucial to prevent deaths from excessive bleeding in surgeries and promote complete restoration of the injury. Some requirements for an ideal wound dressing are rapid hemostatic effect, high swelling capacity, antibacterial properties, biocompatibility, biodegradability, and mechanical strength. However, finding all these properties in a single material remains a challenge. In this context, nanocomposites have demonstrated an excellent capacity for this application because of their multifunctionality. One of the emerging materials used in nanocomposite manufacture is cellulose nanocrystals (CNCs), which are rod-like crystalline nanometric structures present on cellulose chains. These nanoparticles are attractive for wound healing applications because of their high aspect ratio, high mechanical properties, functionality and low density. Hence, this work aimed to present an overview of nanocomposites constituted by CNCs for wound healing applications. The review focuses on the most common materials used as matrices, the types of dressing, and their fabrication techniques. Novel wound dressings composites have improved hemostatic, swelling, and mechanical properties compared to other pure biopolymers while preserving their other biological properties. Films, nanofibers mats, sponges, and hydrogels have been prepared with CNCs nanocomposites, and in vitro and in vivo tests have proved their suitability for wound healing.

Preparation and Properties of Microcrystalline Cellulose/Fish Gelatin Composite Film

As a natural macromolecule-based biomaterial, fish gelatin is used in medical materials for its low pathogen infection risk. However, because of poor mechanical properties, its application has been limited. In this study, microcrystalline cellulose-reinforced fish gelatin (FG/MCC) composite films were prepared with a biological cross-linking agent (genipin) under ultrasonic treatment. SEM micrographs showed that the smooth microstructure of FG film became increasingly disordered with the addition of MCC. The infrared spectrum analysis (FTIR) demonstrated the existence of hydrogen bond interaction between MCC and FG. Compared with the pure FG film, the tensile strength (TS) and modulus of elasticity (MOE) of composite films with MCC were improved, and the elongation at break (EAB) and swelling ratios (SR) were decreased. Ultrasonic treatment could further improve TS, MOE, and SR. When the composite film was prepared with 15% MCC and treated with ultrasound, the TS and MOE increased by 115% and 227%, respectively, while the EAB decreased by 35% and the SR decreased by 4% in comparison with pure FG films. Thermo-gravimetric analysis (TGA) showed that the FG/MCC composite films were stable below 100 °C. The above results indicate that the FG/MCC films have optimistic application prospects in the biomedical field.

A Biodegradable Antibacterial Nanocomposite Based on Oxidized Bacterial Nanocellulose for Rapid Hemostasis and Wound Healing

The development of biodegradable and antibacterial hemostatic materials with high blood absorption to halt the internal hemorrhage of deep noncompressible wounds remains a challenge. In this study, a novel hemostatic nanocomposite (OBC/COL/CS) was fabricated by coupling oxidized bacterial cellulose (OBC) and chitosan (CS) with collagen (COL), that is, during the electrostatic self-assembly of OBC with CS (OBC/CS), COL was ingeniously attached as a functional component by the electrostatic attraction of cationic CS and anionic OBC. The introduction of collagen was anticipated to provide functional properties such as enhanced hemostasis and promotion of wound healing so as to achieve a new functional composite. This study is the first to evaluate the performance of OBC, OBC/CS, and the OBC/COL/CS composite for rapid internal hemostasis using a rat liver injury model. To our knowledge, this is also the first study to report that OBC has a faster biodegradability in vivo than commercial hemostatic oxidized regenerated plant cellulose (ORC). The OBC/COL/CS nanocomposite exhibited appropriate mechanical strength, broad spectrum antimicrobial properties, and excellent biodegradation in vivo. Furthermore, excellent hemostatic efficacy of the composite was confirmed in vivo. OBC/COL/CS exhibited greater procoagulant properties and blood-clotting capability, higher adhesion of erythrocytes and platelets with concomitant lower blood loss, in addition to ultrafast cessation of bleeding, superior to the commercial hemostatic ORC product Surgicel gauze. The results suggest that the OBC/COL/CS is a fast and efficient procoagulant agent with good antibacterial properties and great potential for use as an absorbable hemostat for control of internal bleeding.

Oxidized cellulose-based hemostatic materials

The application of hemostatic agents is essential to prevent significant blood loss and death from excessive bleeding in surgical or emergency scenarios. Oxidized cellulose is an excellent biodegradable and biocompatible derivate of cellulose, which has become one of the most important hemostatic agents used in surgical procedures. However, to date, there has been no comprehensive report assessing oxidized cellulose-based hemostatic materials. Hence, this paper first reviewed the oxidation preparation, cellulose origin and structure, as well as biodegradability and safety of oxidized cellulose. Then a comprehensive review regarding the hemostatic mechanisms, various forms, modification, and current commercially available products of oxidized cellulose is discussed, which emphatically presents the most significant developments in the recent scientific literature. In conclusion, this paper summarizes the latest developments in oxidized cellulose-based hemostatic materials and provides a reference for further research and development in this field.

Vertical ridge augmentation using a porous composite of uncalcined hydroxyapatite and poly-DL-lactide enriched with types 1 and 3 collagen

BACKGROUND

Previous studies have shown that porous composite blocks containing uncalcined hydroxyapatite (u-HA; 70 wt%) with a scaffold of poly-DL-lactide (PDLLA, 30 wt%) are biodegradable, encourage appropriate bone formation, and are suitable for use as a bone substitute in vertical ridge augmentation. The present study aimed to accelerate osteogenesis in vertical ridge formation by adding types 1 and 3 collagen to the u-HA/PDLLA blocks and assessing the effect.

MATERIAL AND METHODS

The bone substitute in the present study comprised porous composite blocks of u-HA (70 wt%) with a PDLLA (27-29 wt%) scaffold and enriched with types 1 and 3 collagen (1.7 ~ 3.4 wt%). The control blocks were composed of u-HA (70 wt%) and PDLLA (30 wt%). The materials were formed into 8-mm diameter, 2-mm high discs and implanted onto the cranial bones of six rabbits. The animals were sacrificed 4 weeks after implantation, and histological and histomorphometrical analyses were performed to quantitatively evaluate newly formed bone.

RESULTS

New bone formation occurred with both block types, showing direct contact with the original bone. Mean ± standard deviation bone formation was significantly greater in the experimental blocks (25.6% ± 4.8%) than in the control blocks (17.0% ± 4.7%).

CONCLUSIONS

Histological and histomorphometrical observations indicated that new bone was formed with both block types. The u-HA/PDLLA block with types 1 and 3 collagen is a more promising candidate for vertical ridge augmentation than the u-HA/PDLLA alone block.

Oxidized regenerated cellulose cross-linked gelatin microparticles for rapid and biocompatible hemostasis: A versatile cross-linking agent

Effective hemostatic materials are of utmost importance for preventing bleeding in emergencies and critical injuries. Combining biodegradability, good hemostatic properties and biocompatibility, gelatin is one of the most reliable materials clinically used for preventing internal bleeding in surgeries and for stopping external hemorrhage. Cross-linking is a useful method for enhancing the absorption capacity of gelatin and for controlling the degradation process. Existing and commonly used aldehyde-containing cross-linking agents lack reliability with respect to the control of hemostatic effect, solubility and toxicity. In this study; gelatin was cross-linked with sodium oxidized regenerated cellulose (NaORC) to produce hemostatic microparticles. The NaORC was used at different ratios; and the studies on hemostatic efficiency and cytotoxicity under in vitro conditions demonstrated rapid arrest of bleeding alongside biocompatibility. These microparticles employing NaORC as a cross-linking agent for the first time demonstrated a unique structure for stopping bleeding with biocompatibility, and opened the way for different forms of cross-linked structures to be used in other biomaterials applications.

Oxidized Regenerated Cellulose Can Reduce Hidden Blood Loss after Total Hip Arthroplasty: A Retrospective Study

Background: There is a large amount of hidden blood loss (HBL) after total hip arthroplasty (THA), but the effective and safe methods to reduce HBL are still controversial. Methods: Sixty-nine consecutive patients who underwent THA in our hospital from January 2015 to December 2015 were analyzed retrospectively. The patients were divided into two groups, Group A (THA without oxidized regenerated cellulose) and Group B (THA with oxidized regenerated cellulose). Demographics, perioperative laboratory values, intraoperative data, blood loss, transfusion rate, transfusion reactions, and surgical complications were collected and analyzed. Results: A total of 37 (54%) patients used oxidized regenerated cellulose (ORC) in operation. The total blood loss (TBL), postoperative blood loss (PBL), hemoglobin (Hb) loss, and hidden blood loss (HBL) in group B were significantly lower than in group A. Conclusions: The use of ORC to fill the bone surface and soft tissue gap before incision closure can effectively reduce HBL and may be a potential treatment for blood prevention after THA.

Synthesis and properties of poly(DEX-GMA/AAc) microgel particle as a hemostatic agent

Poly(DEX-GMA/AAc) microgel particles were designed for the staunching of bleeding through absorption of water in blood and forming a gelled film as a barrier.