Strategies to improve chitosan hemocompatibility: A review

Facile Fabrication of Multifunctional Hydrogel Nanoweb Coating Using Carboxymethyl Chitosan-Based Short Nanofibers for Blood-Contacting Medical Devices

Blood-contacting medical devices (BCDs) require antithrombotic, antibacterial, and low-friction surfaces. Incorporating a nanostructured surface with the functional hydrogel onto BCD surfaces can enhance the performances; however, their fabrication remains challenging. Here, we introduce a straightforward method to fabricate a multifunctional hydrogel-based nanostructure on BCD surfaces using O-carboxymethyl chitosan-based short nanofibers (CMC-SNFs). CMC-SNFs, fabricated via electrospinning and cutting processes, are easily sprayed and entangled onto the BCD surface. The deposited CMC-SNFs form a robust nanoweb layer via fusion at the contact area of the nanofiber interfaces. The superhydrophilic CMS-SNF nanoweb surface creates a water-bound layer that effectively prevents the nonspecific adhesion of bacteria and blood cells, thereby enhancing both antimicrobial and antithrombotic performances. Furthermore, the CMC-SNF nanoweb exhibits excellent lubricity and durability on the bovine aorta. The demonstration results of the CMC-SNF coating on catheters and sheaths provide evidence of its capability to apply multifunctional surfaces simply for diverse BCDs.

Chitosan alchemy: transforming tissue engineering and wound healing

Chitosan, a biopolymer acquired from chitin, has emerged as a versatile and favorable material in the domain of tissue engineering and wound healing. Its biocompatibility, biodegradability, and antimicrobial characteristics make it a suitable candidate for these applications. In tissue engineering, chitosan-based formulations have garnered substantial attention as they have the ability to mimic the extracellular matrix, furnishing an optimal microenvironment for cell adhesion, proliferation, and differentiation. In the realm of wound healing, chitosan-based dressings have revealed exceptional characteristics. They maintain a moist wound environment, expedite wound closure, and prevent infections. These formulations provide controlled release mechanisms, assuring sustained delivery of bioactive molecules to the wound area. Chitosan's immunomodulatory properties have also been investigated to govern the inflammatory reaction during wound healing, fostering a balanced healing procedure. In summary, recent progress in chitosan-based formulations portrays a substantial stride in tissue engineering and wound healing. These innovative approaches hold great promise for enhancing patient outcomes, diminishing healing times, and minimizing complications in clinical settings. Continued research and development in this field are anticipated to lead to even more sophisticated chitosan-based formulations for tissue repair and wound management. The integration of chitosan with emergent technologies emphasizes its potential as a cornerstone in the future of regenerative medicine and wound care. Initially, this review provides an outline of sources and unique properties of chitosan, followed by recent signs of progress in chitosan-based formulations for tissue engineering and wound healing, underscoring their potential and innovative strategies.

A CO-releasing coating based on carboxymethyl chitosan-functionalized graphene oxide for improving the anticorrosion and biocompatibility of magnesium alloy stent materials

Due to its biofunctions similar to NO, the CO gas signaling molecule has gradually shown great potential in cardiovascular biomaterials for regulating the in vivo performances after the implantation and has received increasing attention. To construct a bioactive surface with CO-releasing properties on the surface of magnesium-based alloy to augment the anticorrosion and biocompatibility, graphene oxide (GO) was firstly modified using carboxymethyl chitosan (CS), and then CO-releasing molecules (CORM401) were introduced to synthesize a novel biocompatible nanomaterial (GOCS-CO) that can release CO in the physiological environments. The GOCS-CO was further immobilized on the magnesium alloy surface modified by polydopamine coating with Zn2+ (PDA/Zn) to create a bioactive surface capable of releasing CO in the physiological environment. The outcomes showed that the CO-releasing coating can not only significantly enhance the anticorrosion and abate the corrosion degradation rate of the magnesium alloy in a simulated physiological environment, but also endow it with good hydrophilicity and a certain ability to adsorb albumin selectively. Owing to the significant enhancement of anticorrosion and hydrophilicity, coupled with the bioactivity of GOCS, the modified sample not only showed excellent ability to prevent platelet adhesion and activation and reduce hemolysis rate but also can promote endothelial cell (EC) adhesion, proliferation as well as the expression of nitric oxide (NO) and vascular endothelial growth factor (VEGF). In the case of CO release, the hemocompatibility and EC growth behaviors were further significantly improved, suggesting that CO molecules released from the surface can significantly improve the hemocompatibility and EC growth. Consequently, the present study provides a novel surface modification method that can simultaneously augment the anticorrosion and biocompatibility of magnesium-based alloys, which will strongly promote the research and application of CO-releasing bioactive coatings for surface functionalization of cardiovascular biomaterials and devices.

Chitin whisker/chitosan liquid crystal hydrogel assisted scaffolds with bone-like ECM microenvironment for bone regeneration

Natural bone exhibits a complex anisotropic and micro-nano hierarchical structure, more importantly, bone extracellular matrix (ECM) presents liquid crystal (LC) phase and viscoelastic characteristics, providing a unique microenvironment for guiding cell behavior and regulating osteogenesis. However, in bone tissue engineering scaffolds, the construction of bone-like ECM microenvironment with exquisite microstructure is still a great challenge. Here, we developed a novel polysaccharide LC hydrogel supported 3D printed poly(l-lactide) (PLLA) scaffold with bone-like ECM microenvironment and micro-nano aligned structure. First, we prepared a chitin whisker/chitosan polysaccharide LC precursor, and then infuse it into the pores of 3D printed PLLA scaffold, which was previously surface modified with a polydopamine layer. Next, the LC precursor was chemical cross-linked by genipin to form a hydrogel network with bone-like ECM viscoelasticity and LC phase in the scaffold. Subsequently, we performed directional freeze-casting on the composite scaffold to create oriented channels in the LC hydrogel. Finally, we soaked the composite scaffold in phytic acid to further physical cross-link the LC hydrogel through electrostatic interactions and impart antibacterial effects to the scaffold. The resultant biomimetic scaffold displays osteogenic activity, vascularization ability and antibacterial effect, and is expected to be a promising candidate for bone repair.

Assessment of the ability of Pseudomonas aeruginosa and Staphylococcus aureus to create biofilms during wound healing in a rat model treated with carboxymethyl cellulose/carboxymethyl chitosan hydrogel containing EDTA

The primary objective of this study was to develop a carboxymethyl cellulose (CMC) and carboxymethyl chitosan (CMCS) hydrogel containing ethylene diamine tetra acetic acid (EDTA) as the materials for wound healing. CMC and CMCS solutions were prepared with a concentration of 4% (w/v). These solutions were made using normal saline serum with a concentration of 0.5% (v/v). Additionally, EDTA with the concentrations of 0.01%, 0.05%, 0.1%, 0.5%, 1%, and 2% (w/v) was included in the prepared polymer solution. The analysis of the hydrogels revealed that they possess porous structures with interconnected pores, with average in size 88.71 ± 5.93 μm. The hydrogels exhibited a swelling capacity of up to 60% of their initial weight within 24 h, as indicated by the weight loss and swelling measurements. The antibacterial experiments showed that the formulated CMC/CMCS/EDTA 0.5% hydrogel inhibited the growth of Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, the produced hydrogels were haemocompatible and biocompatible. At the last stage, the evaluation of wound healing in the animal model demonstrated that the use of the produced hydrogels significantly improved the process of wound healing. Finally, the findings substantiated the effectiveness of the formulated hydrogels as the materials for promoting wound healing and antibacterial agents.

Chitosan particles embedded bacterial nanocellulose flat membrane for hemodialysis

The development of bio-based hemodialysis membranes continues to be a challenge. Bacterial nanocellulose (BNC) membranes show potential in hemodialysis but can hardly retain beneficial proteins. Here, chitosan particles/bacterial nanocellulose (CSP/BNC) membranes were designed to efficiently remove uremic toxins and retain beneficial proteins. First, CSPs were synthesized in situ within a BNC membrane by ionic gelation following negative pressure impregnation. Subsequently, these membranes were thoroughly characterized. Compared with the BNC membrane, the pore volume and pore size of the 3 % CSP/BNC membrane decreased by 42.2 % and 32.1 %, respectively. The increased 22.2 times of Young's modulus and 88.9 % of tensile strength in the 3 % CSP/BNC membrane confirmed enhanced mechanical property. The sieving coefficient of bovine serum albumin decreased to 0.05 ± 0.03 in the 3 % CSP/BNC membrane. Moreover, the CSP/BNC membrane exhibited good hemocompatibility and cytocompatibility. The simulated dialysis results showed that the 3 % CSP/BNC membrane exhibited high clearance of urea (16.37 %/cm2) and lysozyme (3.54 %/cm2), while efficiently retaining bovine serum albumin (98.04 %/cm2). This is the first demonstration of the construction of a BNC-based hemodialysis membrane with in situ CSP formation to effectively regulate the pore properties of the membrane, making the CSP/BNC membrane a promising candidate for hemodialysis applications.

Chitosan-based nanosystems for cancer diagnosis and therapy: Stimuli-responsive, immune response, and clinical studies

Cancer, a global health challenge of utmost severity, necessitates innovative approaches beyond conventional treatments (e.g., surgery, chemotherapy, and radiation therapy). Unfortunately, these approaches frequently fail to achieve comprehensive cancer control, characterized by inefficacy, non-specific drug distribution, and the emergence of adverse side effects. Nanoscale systems based on natural polymers like chitosan have garnered significant attention as promising platforms for cancer diagnosis and therapy owing to chitosan's inherent biocompatibility, biodegradability, nontoxicity, and ease of functionalization. Herein, recent advancements pertaining to the applications of chitosan nanoparticles in cancer imaging and drug/gene delivery are deliberated. The readers are introduced to conventional non-stimuli-responsive and stimuli-responsive chitosan-based nanoplatforms. External triggers like light, heat, and ultrasound and internal stimuli such as pH and redox gradients are highlighted. The utilization of chitosan nanomaterials as contrast agents or scaffolds for multimodal imaging techniques e.g., magnetic resonance, fluorescence, and nuclear imaging is represented. Key applications in targeted chemotherapy, combination therapy, photothermal therapy, and nucleic acid delivery using chitosan nanoformulations are explored for cancer treatment. The immunomodulatory effects of chitosan and its role in impacting the tumor microenvironment are analyzed. Finally, challenges, prospects, and future outlooks regarding the use of chitosan-based nanosystems are discussed.

Progress in injectable hydrogels for the treatment of incompressible bleeding: an update

Uncontrollable haemorrhage from deep, noncompressible wounds remains a persistent and intractable challenge, accounting for a very high proportion of deaths in both war and disaster situations. Recently, injectable hydrogels have been increasingly studied as potential haemostatic materials, highlighting their enormous potential for the management of noncompressible haemorrhages. In this review, we summarize haemostatic mechanisms, commonly used clinical haemostatic methods, and the research progress on injectable haemostatic hydrogels. We emphasize the current status of injectable hydrogels as haemostatic materials, including their physical and chemical properties, design strategy, haemostatic mechanisms, and application in various types of wounds. We discuss the advantages and disadvantages of injectable hydrogels as haemostatic materials, as well as the opportunities and challenges involved. Finally, we propose cutting-edge research avenues to address these challenges and opportunities, including the combination of injectable hydrogels with advanced materials and innovative strategies to increase their biocompatibility and tune their degradation profile. Surface modifications for promoting cell adhesion and proliferation, as well as the delivery of growth factors or other biologics for optimal wound healing, are also suggested. We believe that this paper will inform researchers about the current status of the use of injectable haemostatic hydrogels for noncompressible haemorrhage and spark new ideas for those striving to propel this field forward.

Characterization and In-vitro Study of Micro-encapsulation Chitosan Alginate of Single-bulb Garlic Extract

BACKGROUND

Single-bulb garlic extract (SBGE) contains more active compounds than regular garlic, but it is unstable and easily degraded in the digestive tract. SBGE is expected to be protected by microencapsulation chitosan-alginate (MCA).

OBJECTIVE

The present study aimed to characterize and assess the antioxidant activity, hemocompatibility, and toxicity of MCA-SBGE in 3T3-L1 cells.

METHODS

The research procedures consist of extraction of single bulb garlic, preparation of MCASBGE, Particle Size Analyzer (PSA), FTIR analysis, DPPH assay, hemocompatibility test, and MTT assay.

RESULTS

The average size of MCA-SGBE was 423.7 ± 2.8 nm, the polydispersity index (PdI) was 0.446 ± 0.022, and the zeta potential was -24.5 ± 0.4 mV. MCA-SGBE was spherical with a diameter range of 0.65-0.9 μm. A shift in absorption and addition of functional groups was found in SBGE after encapsulation. MCA-SBGE, at a concentration of 24 x 103 ppm, has higher antioxidants than SBGE. The hemocompatibility test shows the hemolysis of MCA-SBGE lower than SBGE. MCA-SBGE was not toxic to 3T3-L1 cells with cell viability percentage above 100% at all concentrations.

CONCLUSION

MCA-SBGE characterization has microparticle criteria with homogeneous PdI values, low particle stability, and spherical morphology. The results showed that SBGE and MCA-SBGE are nonhemolytic, compatible with red blood cells, and non-toxic to 3T3-L1 cells.

A nitric oxide-catalytically generating carboxymethyl chitosan/sodium alginate hydrogel coating mimicking endothelium function for improving the biocompatibility

Thanks to their outstanding mechanical properties and corrosion resistance in physiological environments, titanium and its alloys are broadly explored in the field of intravascular devices. However, the biocompatibility is insufficient, causing thrombus formation and even implantation failure. In this study, inspired by the functions of endothelial glycocalyx and the NO-releasing of endothelial cells (ECs), a biomimetic coating (TNTA-Se) with three-dimensional gel-like structures and NO-catalytically generating ability was constructed on the titanium surface. To this end, the titanium alloy was firstly anodized and then annealed to form nanotube structures imitating the three-dimensional villous of glycocalyx, followed by the preparation of the Cu2+-loaded polydopamine intermediate layer for the immobilization of carboxymethyl chitosan and sodium alginate to form the hydrogel structure. Finally, an organoselenium compound (selenocystamine) as an active catalyst was covalently immobilized on the surface to develop a bioactive coating mimicking endothelial function with NO-generating activity. The surface morphologies and chemical structures of the biomimetic coating were characterized by scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and the results indicated that the NO-catalytically generating hydrogel coating was successfully constructed. The results of water contact angle and protein adsorption suggested that the TNTA-Se coating exhibited excellent hydrophilicity, the promotion of bovine serum albumin (BSA) adsorption while the inhibition of fibrinogen (FIB) adsorption. Upon the addition of NO donor S-nitroso glutathione (GSNO) and reducing agent glutathione (GSH), the surface (TNTA-NO) displayed excellent blood compatibility and cytocompatibility to ECs. Compared with other surfaces, the TNTA-NO coating can not only further promote BSA adsorption and inhibit the adhesion and activation of platelets as well as hemolysis, but also significantly enhance ECs adhesion and proliferation and up-regulate VEGF and NO expression of ECs. The current study demonstrated that the NO-catalytically generating hydrogel coating on the titanium alloy can mimic the glycocalyx structure and endothelium function to catalyze a large number of NO donors in human blood to produce NO, and thus simultaneously enhance the surface hemocompatibility and endothelialization, representing a promising strategy for long-term cardiovascular implants of titanium-based devices.

Self-Assembled Amphiphilic Chitosan Nanomicelles: Synthesis, Characterization and Antibacterial Activity

Although amphiphilic chitosan has been widely studied as a drug carrier for drug delivery, fewer studies have been conducted on the antimicrobial activity of amphiphilic chitosan. In this study, we successfully synthesized deoxycholic acid-modified chitosan (CS-DA) by grafting deoxycholic acid (DA) onto chitosan C2-NH2, followed by grafting succinic anhydride, to prepare a novel amphiphilic chitosan (CS-DA-SA). The substitution degree was 23.93% for deoxycholic acid and 29.25% for succinic anhydride. Both CS-DA and CS-DA-SA showed good blood compatibility. Notably, the synthesized CS-DA-SA can self-assemble to form nanomicelles at low concentrations in an aqueous environment. The results of CS, CS-DA, and CS-DA-SA against Escherichia coli and Staphylococcus aureus showed that CS-DA and CS-DA-SA exhibited stronger antimicrobial effects than CS. CS-DA-SA may exert its antimicrobial effect by disrupting cell membranes or forming a membrane on the cell surface. Overall, the novel CS-DA-SA biomaterials have a promising future in antibacterial therapy.

Surface Engineering of Bioactive Coatings for Improved Stent Hemocompatibility: A Comprehensive Review

Cardiovascular diseases continue to be a major contributor to illness and death on a global scale, and the implementation of stents has given rise to a revolutionary transformation in the field of interventional cardiology. The thrombotic and restenosis complications associated with stent implantation pose ongoing challenges. In recent years, bioactive coatings have emerged as a promising strategy to enhance stent hemocompatibility and reduce thrombogenicity. This review article provides an overview of the surface engineering techniques employed to improve the hemocompatibility of stents and reduce thrombus formation. It explores the mechanisms underlying thrombosis and discusses the factors influencing platelet activation and fibrin formation on stent surfaces. Various bioactive coatings, including anticoagulant agents, antiplatelet agents, and surface modifications, are discussed in detail, highlighting their potential in reducing thrombogenicity. This article also highlights a multitude of surface modification techniques which can be harnessed to enhance stent hemocompatibility including plasma treatment, physical vapor deposition (PVD), chemical vapor deposition (CVD), and electrodeposition. These techniques offer precise control over surface properties such as roughness, charge, and composition. The ultimate goal is to reduce platelet adhesion, tailor wettability, or facilitate the controlled release of bioactive agents. Evaluation methods for assessing hemocompatibility and thrombogenicity are also reviewed, ranging from in vitro assays to animal models. Recent advances in the field, such as nanotechnology-based coatings and bioactive coatings with controlled drug release systems, are highlighted. Surface engineering of bioactive coatings holds great promise for enhancing the long-term outcomes of stent implantation by enhancing hemocompatibility and reducing thrombogenicity. Future research directions and potential clinical applications are discussed, underscoring the need for continued advancements in this field.

Metformin derivatives - Researchers' friends or foes?

Metformin has been used for ages to treat diabetes mellitus due to its safety profile and low cost. However, metformin has variable pharmacokinetics in patients, and due to its poor oral absorption, the therapeutic doses are relatively high, causing unpleasant gastrointestinal adverse effects. Therefore, novel derivatives of metformin have been synthesized during the past decades. Particularly, after the mid-2000 s, when organic cation transporters were identified as the main metformin carriers, metformin derivatives have been under intensive investigation. Nevertheless, due to the biguanide structure, derivatives of metformin have been challenging to synthesize. Moreover, the mechanisms of metformin's action are not fully understood to date, and since it has multifunctional properties, the interests have switched to re-purposing for other diseases. Indeed, metformin derivatives have been demonstrated in many cases to be more effective than metformin itself and have the potential to be used in different diseases, including several types of cancers and neurodegenerative diseases. On the other hand, the pleiotropic nature of metformin and its derivatives can also create challenges. Not all properties are fit for all diseases. In this review, the history of the development of metformin-like compounds is summarized, and insights into their potential for future drug discovery are discussed.

Human beta defensin-2 loaded PLGA nanoparticles impregnated in collagen-chitosan composite scaffold for the management of diabetic wounds

Diabetic wound (DW) is the most devastating complication resulting in significant mortality and morbidity in diabetic patients. The standard treatment of DW care fails to address the prerequisites of treating DW owing to its multifactorial pathophysiology. Henceforth, developing a single treatment strategy to handle all the loopholes may effectively manage DW. The objective of the current study was to formulate Human beta defensin-2 (HBD-2) loaded Poly (lactic-co-glycolic acid) (PLGA) nanoparticle impregnated in collagen/chitosan (COL-CS) composite scaffolds for the accelerated healing of DW. Upon investigation, the developed biodegradable crosslinked scaffold possesses low matrix degradation, optimum porosity, and sustained drug release than the non-crosslinked scaffold. In vitro studies revealed that the HBD-2 COL-CS scaffold was biocompatible and accelerated cell migration and angiogenesis. The HBD-2 COL-CS scaffold showed significant antimicrobial activity in S. aureus, E. coli, and P. aeruginosa. The in vivo studies revealed that the HBD-2 COL-CS treated group accelerated healing compared to those in COL-CS and control groups. The ELISA results indicated a significant decrease in MMP-9, TNF-α, MPO, NAG, and NO with an increase in IL-10 in HBD-2 COL-CS treated group. The accelerated healing in HBD-2 COL-CS treated group might be due to the synergistic effects of PLGA (collagen synthesis and deposition and positive angiogenic effect), HBD-2 (anti-inflammatory, antibacterial, positive angiogenic effect, cell proliferation, and migration), COL (established wound healer and stabilizer) and CS (antibacterial, controlled drug release).

PEGylated and functionalized polylactide-based nanocapsules: An overview

Polymeric nanocapsules (NC) are versatile mixed vesicular nanocarriers, generally containing a lipid core with a polymeric wall. They have been first developed over four decades ago with outstanding applicability in the cosmetic and pharmaceutical fields. Biodegradable polyesters are frequently used in nanocapsule preparation and among them, polylactic acid (PLA) derivatives and copolymers, such as PLGA and amphiphilic block copolymers, are widely used and considered safe for different administration routes. PLA functionalization strategies have been developed to obtain more versatile polymers and to allow the conjugation with bioactive ligands for cell-targeted NC. This review intends to provide steps in the evolution of NC since its first report and the recent literature on PLA-based NC applications. PLA-based polymer synthesis and surface modifications are included, as well as the use of NC as a novel tool for combined treatment, diagnostics, and imaging in one delivery system. Furthermore, the use of NC to carry therapeutic and/or imaging agents for different diseases, mainly cancer, inflammation, and infections is presented and reviewed. Constraints that impair translation to the clinic are discussed to provide safe and reproducible PLA-based nanocapsules on the market. We reviewed the entire period in the literature where the term "nanocapsules" appears for the first time until the present day, selecting original scientific publications and the most relevant patent literature related to PLA-based NC. We presented to readers a historical overview of these Sui generis nanostructures.

Synthesis, optimization, and cell response investigations of natural-based, thermoresponsive, injectable hydrogel: An attitude for 3D hepatocyte encapsulation and cell therapy

For the purpose of developing a 3D vehicle for the delivery of hepatocytes in cell therapy, the improved system of crosslinker and new gelling agent combinations consisting of glycerophosphate and sodium hydrogen carbonate have been employed to produce injectable, thermoresponsive hydrogels based on chitosan and silk fibroin. Adjusting the polymer-to-gelling agent ratio and utilizing a chemical crosslinker developed hydrogel scaffolds with optimal gelling time and pH. Applying sodium hydrogen carbonate neutralizes chitosan while keeping its thermoresponsive characteristics and decreases glycerophosphate from 60% to 30%. Genipin boosts the mechanical properties of hydrogel without affecting the gel time. Due to their stable microstructure and lower amine availability, genipin-containing materials have a low swelling ratio, around six compared to eight for those without genipin. Hydrogels that are crosslinked degrade about half as fast as those that are not. The slowerr degradation of Silk fibroin compared to chitosan makes it an efficient degradation inhibitor in silk-containing formulations. All of the optimized samples showed less than 5% hemolytic activity, indicating that they lacked hemolytic characteristics. The acceptable cell viability in crosslinked hydrogels ranges from 72% to 91% due to the decreasing total salt concentration, which protects cells from hyperosmolality. The pH of hydrogels and their interstitial pores kept most encapsulated cells alive and functioning for 24 h. Urea levels are higher in the encapsulation condition compared to HepG2 cultivated alone, and this may be due to cell-matrix interactions that boost liver-specific activity. Urea synthesis in genipin crosslinked hydrogels increased dramatically from day 1 (about 4 mg dl^-1) to day 3 (approximately 6 mg dl^-1), suggesting the enormous potential of these hydrogels for cell milieu preparation. All mentioned findings represent that the optimized system may be a promising candidate for liver regeneration.

Bio-inspired hemocompatible surface modifications for biomedical applications

When blood first encounters the artificial surface of a medical device, a complex series of biochemical reactions is triggered, potentially resulting in clinical complications such as embolism/occlusion, inflammation, or device failure. Preventing thrombus formation on the surface of blood-contacting devices is crucial for maintaining device functionality and patient safety. As the number of patients reliant on blood-contacting devices continues to grow, minimizing the risk associated with these devices is vital towards lowering healthcare-associated morbidity and mortality. The current standard clinical practice primarily requires the systemic administration of anticoagulants such as heparin, which can result in serious complications such as post-operative bleeding and heparin-induced thrombocytopenia (HIT). Due to these complications, the administration of antithrombotic agents remains one of the leading causes of clinical drug-related deaths. To reduce the side effects spurred by systemic anticoagulation, researchers have been inspired by the hemocompatibility exhibited by natural phenomena, and thus have begun developing medical-grade surfaces which aim to exhibit total hemocompatibility via biomimicry. This review paper aims to address different bio-inspired surface modifications that increase hemocompatibility, discuss the limitations of each method, and explore the future direction for hemocompatible surface research.

Chitosan IR806 dye-based polyelectrolyte complex nanoparticles with mitoxantrone combination for effective chemo-photothermal therapy of metastatic triple-negative breast cancer

Chemo-photothermal therapy is one of the emerging therapies for treating triple-negative breast cancer. In this study, we have used ionotropic gelation method to fabricate chitosan and IR806 dye-based polyelectrolyte complex (CIR-PEx) nanoparticles. These nano-complexes were in size range of 125 ± 20 nm. The complexation of IR 806 dye with chitosan improved photostability, photothermal transduction, and showed excellent biocompatibility. Cancer cells treated with CIR-PEx NPs enhanced intracellular uptake within 5 h of incubation and also displayed mitochondrial localization. With the combination of CIR-PEx NPs and a chemotherapeutic agent (i.e., mitoxantrone, MTX), a significant decline in cancer cell viability was observed in both 2D and 3D cell culture models. The chemo-photothermal effect of CIR-PEx NPs + MTX augmented apoptosis in cancer cells when irradiated with NIR light. Furthermore, when tested in the 4 T1-tumor model, the chemo-photothermal therapy showed a drastic decline in tumor volume and inhibited metastatic lung nodules. The localized hyperthermia caused by photothermal therapy reduced the primary tumor burden, and the chemotherapeutic activity of mitoxantrone further complemented by inhibiting the spread of cancer cells. The proposed chemo-photothermal therapy combination could be a promising strategy for treating triple-negative metastatic breast cancer.

Bioinspired Hydrogels as Platforms for Life-Science Applications: Challenges and Opportunities

Hydrogels, as interconnected networks (polymer mesh; physically, chemically, or dynamic crosslinked networks) incorporating a high amount of water, present structural characteristics similar to soft natural tissue. They enable the diffusion of different molecules (ions, drugs, and grow factors) and have the ability to take over the action of external factors. Their nature provides a wide variety of raw materials and inspiration for functional soft matter obtained by complex mechanisms and hierarchical self-assembly. Over the last decade, many studies focused on developing innovative and high-performance materials, with new or improved functions, by mimicking biological structures at different length scales. Hydrogels with natural or synthetic origin can be engineered as bulk materials, micro- or nanoparticles, patches, membranes, supramolecular pathways, bio-inks, etc. The specific features of hydrogels make them suitable for a wide variety of applications, including tissue engineering scaffolds (repair/regeneration), wound healing, drug delivery carriers, bio-inks, soft robotics, sensors, actuators, catalysis, food safety, and hygiene products. This review is focused on recent advances in the field of bioinspired hydrogels that can serve as platforms for life-science applications. A brief outlook on the actual trends and future directions is also presented.

Triggered and controlled release of bioactives in food applications

Bioactive compounds (e.g., nutraceuticals, micronutrients, antimicrobial, antioxidant) are added to food products and formulations to enhance sensorial/nutritional attributes and/or shelf-life. Many of these bioactives are susceptible to degradation when exposed to environmental and processing factors. Others involve in undesirable interactions with food constituents. Encapsulation is a useful tool for addressing these issues through various stabilization mechanisms. Besides protection, another important requirement of encapsulation is to design a carrier that predictably releases the encapsulated bioactive at the target site to elicit its intended functionality. To this end, controlled release carrier systems derived from interactive materials have been developed and commercially exploited to meet the requirements of various applications. This chapter provides an overview on basic controlled and triggered release concepts relevant to food and active packaging applications. Different approaches to encapsulate bioactive compounds and their mode of release are presented, from simple blending with a compatible matrix to complex multiphase carrier systems. To further elucidate the mass transport processes, selected diffusion and empirical release kinetic models are presented, along with their brief historical significance. Finally, interactive carriers that are responsive to moisture, pH, thermal and chemical stimuli are presented to illustrate how these triggered release mechanisms can be useful for food applications.

Interleukin-12 Plasmid DNA Delivery by N-[(2-Hydroxy-3-trimethylammonium)propyl]chitosan-Based Nanoparticles

Cationic polysaccharides are capable of forming polyplexes with nucleic acids and are considered promising polymeric gene carriers. The objective of this study was to evaluate the transfection efficiency and cytotoxicity of N-[(2-hydroxy-3-trimethylammonium)propyl] chitosan salt (HTCS), a quaternary ammonium derivative of chitosan (CS), which benefits from non-ionizable positive charges. In this work, HTCS with a full quaternization of amino groups and a molar mass of 130,000 g·mol⁻¹ was synthesized to use for delivery of a plasmid encoding the interleukin-12 (IL-12) gene. Thus, a polyplex based on HTCS and the IL-12 plasmid was prepared and then was characterized in terms of particle size, zeta potential, plasmid condensation ability, and protection of the plasmid against enzymatic degradation. We showed that HTCS was able to condense the IL-12 plasmid by the formation of polyplexes in the range of 74.5 ± 0.75 nm. The level of hIL-12 production following the transfection of the cells with HTCS polyplexes at a C/P ratio of 8:1 was around 4.8- and 2.2-fold higher than with CS and polyethylenimine polyplexes, respectively. These findings highlight the role of HTCS in the formation of polyplexes for the efficient delivery of plasmid DNA.

Environmentally friendly fabrication of electrospun nanofibers made of polycaprolactone, chitosan and κ-carrageenan (PCL/CS/κ-C)

Electrospun fibers based on biodegradable polyanionic or polycationic biopolymers are highly beneficial for biomedical applications. In this work, electrospun nanofibers made from poly(epsilon caprolactone) (PCL), chitosan (CS) and κ-carrageenan (κ-C) were successfully fabricated using several mixtures of benign solvents containing formic acid (FA) and acetic acid (AA). The addition of κ-carrageenan improved the preparation procedure for the production of PCL/CS fibers by electrospinning. Moreover, a polymer mixture was selected to be stored at -20 °C for one month with the purpose to study the properties of the resulting fiber mat. The results indicated that fiber characteristics were not seriously compromised compared to the ones of those fabricated with the original solution, which represents an important reduction in produced waste. Thus, the interactions that occur between positively and negatively charged hydrophilic polysaccharides might induce higher stability to the linear aliphatic polyester in the polymer mixture. All fiber mats were morphologically, physico-chemically and mechanically characterized, showing average fiber diameters in the nano scale. A direct cell viability assay using ST-2 cells demonstrated cell proliferation after 7 days of incubation for all prepared fiber mats, confirming their suitability as potential candidates for bone tissue engineering and wound healing applications.

Chitosan nanofiber biocomposites for potential wound healing applications: Antioxidant activity with synergic antibacterial effect

Bacterial wound infection is one of the most common nosocomial infections. The unnecessary employment of antibiotics led to raising the growth of antibiotic-resistant bacteria. Accordingly, alternative armaments capable of accelerating wound healing along with bactericidal effects are urgently needed. Considering this, we fabricated chitosan (CS)/polyethylene oxide (PEO) nanofibers armed with antibacterial silver and zinc oxide nanoparticles. The nanocomposites exhibited a high antioxidant effect and antibacterial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Besides, based on the results of the cell viability assays, the optimum concentration of ZnONPs and AgNPs in the nanofibrous mats is 0.2% w/v and 0.08% w/v respectively and had no cytotoxicity on fibroblast cells. The scaffold also showed good blood compatibility according to the effects of coagulation time. As well as significant fibroblast migration and proliferation on the wound margin, according to wound-healing assay. All in all, the developed biocompatible, antioxidant, and antibacterial Ag-ZnO NPs incorporated CS/PEO nanofibrous mats showed their potential as an effective wound dressing.

Chitosan-coated pore wall polycaprolactone three-dimensional porous scaffolds fabricated by porogen leaching method for bone tissue engineering: a comparative study on blending technique to fabricate scaffolds

One of the significant challenges in the fabrication of scaffolds for tissue engineering lies in the direct interaction of bioactive agents with cells in the scaffolds matrix, which curbs the effectiveness of bioactive agents resulting in diminished cell recognition and attachment ability of the scaffolds. Here, three-dimensional porous scaffolds were fabricated using polycaprolactone (PCL) and chitosan, by two approaches, i.e., blending and surface coating to compare their overall effectiveness. Blended scaffolds (Chi-PCL) were compared with the scaffolds fabricated using surface coating technique, where chitosan was coated on the pore wall of PCL scaffolds (C-PCL). The C-PCL exhibited a collective improvement in bioactivities of the stem cell on the scaffold, because of the cell compatible environment provided by the presence of chitosan over the scaffolds interface. The C-PCL showed the enhanced cell attachment and proliferation behavior of the scaffolds along with two-fold increase in hemolysis compatibility compared to Chi-PCL. Furthermore, the compression strength in C-PCL increased by 24.52% and 8.62% increase in total percentage porosity compared to Chi-PCL was attained. Along with this, all the bone markers showed significant upregulation in C-PCL scaffolds, which supported the surface coating technique over the conventional methods, even though the pore size of C-PCL was compromised by 19.98% compared with Chi-PCL.

Cliv-92-Loaded Glycyrrhetinic Acid-Modified Chitosan Nanoparticles for Enhanced Hepatoprotection-Preparation, Characterization, and In Vivo Evaluation

Cliv-92 is a mixture of three structurally similar coumarinolignoids and a proven hepatoprotective agent. Low aqueous solubility and poor bioavailability are notable hindrances for its further use. Therefore, glycyrrhetinic acid-linked chitosan nanoparticles loaded with Cliv-92 were prepared for active targeting to the liver. The nanoparticles were prepared by the ionic gelation method to avoid the use of toxic solvents/rigorous agitation. The method of preparation was optimized using a central composite design with independent variables, namely polymer: drug ratio (3:1, w/w), crosslinker concentration (0.5%), and stirring speed (750 rpm). The optimized nanoparticles had a mean particle size of 185.17 nm, a polydispersity index of 0.41, a zeta potential of 30.93 mV, and a drug loading of 16.30%. The prepared formulation showed sustained release of approximately 63% of loaded Cliv-92 over 72 h. The nanoparticles were freeze-dried for long-term storage and further characterized. The formulation was found to be biocompatible for parenteral delivery. In vivo imaging study showed that optimized nanoparticles were preferentially accumulated in the liver and successfully targeting the liver. The present study successfully demonstrated the improved pharmacokinetic properties (≈12% relative bioavailability) and efficacy profile (evidenced by in vivo and histopathological studies) of fabricated Cliv-92 nanoparticles.

Surface modification strategies to improve titanium hemocompatibility: a comprehensive review

Titanium and its alloys are widely used in different biomaterial applications due to their remarkable mechanical properties and bio-inertness. However, titanium-based materials still face some challenges, with an emphasis on hemocompatibility. Blood-contacting devices such as stents, heart valves, and circulatory devices are prone to thrombus formation, restenosis, and inflammation due to inappropriate blood-implant surface interactions. After implantation, when blood encounters these implant surfaces, a series of reactions takes place, such as protein adsorption, platelet adhesion and activation, and white blood cell complex formation as a defense mechanism. Currently, patients are prescribed anticoagulant drugs to prevent blood clotting, but these drugs can weaken their immune system and cause profound bleeding during injury. Extensive research has been done to modify the surface properties of titanium to enhance its hemocompatibility. Results have shown that the modification of surface morphology, roughness, and chemistry has been effective in reducing thrombus formation. The main focus of this review is to analyze and understand the different modification techniques on titanium-based surfaces to enhance hemocompatibility and, consequently, recognize the unresolved challenges and propose scopes for future research.

Materials Based on Chitosan and Polylactide: From Biodegradable Plastics to Tissue Engineering Constructions

Abstract

The transition to green chemistry and biodegradable polymers is a logical stage in the development of modern chemical science and technology. In the framework of this review, the advantages, disadvantages, and potential of biodegradable polymers of synthetic and natural origin are compared using the example of polylactide and chitosan as traditional representatives of these classes of polymers, and the possibilities of their combination via obtaining composite materials or copolymers are assessed. The mechanochemical approach to the synthesis of graft copolymers of chitosan with oligolactides/polylactides is considered in more detail.

Biotinylated chitosan macromolecule based nanosystems: A review from chemical design to biological targets

World Health Organization estimates that 30-50% of cancers are preventable by healthy lifestyle choices, early detection and adequate therapy. When the conventional therapeutic strategies are still regulated by the lack of selectivity, multidrug resistance and severe toxic side effects, nanotechnology grants a new frontier for cancer management since it targets cancer cells and spares healthy tissues. This review highlights recent studies using biotin molecule combined with functional nanomaterials used in biomedical applications, with a particular attention on biotinylated chitosan-based nanosystems. Succinctly, this review focuses on five areas of recent advances in biotin engineering: (a) biotin features, (b) biotinylation approaches, (c) biotin functionalized chitosan based nanosystems for drug and gene delivery functions, (d) diagnostic and theranostic perspectives, and (e) author's inputs to the biotin-chitosan based tumour-targeting drug delivery structures. Precisely engineered biotinylated-chitosan macromolecules shaped into nanosystems are anticipated to emerge as next-generation platforms for treatment and molecular imaging modalities applications.

In Vitro Microbiological and Drug Release of Silver/Ibuprofen Loaded Wound Dressing Designed for the Treatment of Chronically Infected Painful Wounds

This study consisted of developing a dressing loaded with silver (Ag) and ibuprofen (IBU) that provides a dual therapy, antibacterial and antalgic, intended for infected painful wounds. Therefore, non-woven polyethyleneterephtalate (PET) textiles nonwovens were pre-treated by cyclodextrin crosslinked with citric acid by a pad/dry/cure process. Then, textiles were impregnated in silver solution followed by a thermal treatment and were then coated by Layer-by-Layer (L-b-L) deposition of a polyelectrolyte multilayer (PEM) system consisting of anionic water-soluble poly(betacyclodextrin citrate) (PCD) and cationic chitosan. Finally, ibuprofen lysinate (IBU-L) was loaded on the PEM coating. We demonstrated the complexation of IBU with native βCD and PCD by phase solubility diagram and ¹H NMR. PEM system allowed complete IBU-L release in 6 h in PBS pH 7.4 batch (USP IV). On the other hand, microbiological tests demonstrated that loaded silver induced bacterial reduction of 4 Log₁₀ against S. aureus and E. coli and tests revealed that ibuprofen lysinate loading did not interfere with the antibacterial properties of the dressing.

Recent advances of emerging green chitosan-based biomaterials with potential biomedical applications: A review

Chitosan is the most abundant natural biopolymer, after cellulose. It is mainly derived from the fungi, shrimp's shells, and exoskeleton of crustaceans, through the deacetylation of chitin. The ecological sustainability associated with its exercise and the flexibility of chitosan owing to its active functional hydroxyl and amino groups makes it a promising candidate for a wide range of applications through a variety of modifications. The biodegradability and biocompatibility of chitosan and its derivatives along with their various chemical functionalities make them promising carriers for pharmaceutical, nutritional, medicinal, environmental, agriculture, drug delivery, and biotechnology applications. The present work aims to provide a detailed and organized description of modified chitosan and its derivatives-based nanomaterials for biomedical applications. We addressed the biological and physicochemical benefits of nanocomposite materials made up of chitosan and its derivatives in various formulations, including improved physicochemical stability and cells/tissue interaction, controlled drug release, and increased bioavailability and efficacy in clinical practice. Moreover, several modification techniques and their effective utilization are also reviewed and collected in this review.

Improvement of the wound healing properties of hydrogels with N-acetylcysteine through their modification with methacrylate-containing polymers

Hydrogels with antioxidant activity have shown to significantly improve the standard of care, because they promote efficient wound healing, i.e. regeneration. N-Acetylcysteine (NAC) is an antioxidant amino acid derivative that promotes complete tissue restoration. However, NAC has anticoagulant properties that may also hinder blood coagulation, which is crucial for hydrogels for wound healing applications. To take advantage of the regenerative activity of NAC while avoiding hampering the hemostasis stage during wound healing, we modified gelatin-NAC with the methacrylate-containing polymers 2-hydroxyethyl methacrylate (H) and poly(ethylene glycol) methyl ether methacrylate (P) to produce Gel-HP-NAC. These hydrogels clotted more blood and faster than Gel and Gel-NAC hydrogels, while maintaining fluid absorption properties adequate to promote wound healing. Similarly, there were more viable human skin fibroblasts after 10 days cultured in Gel-HP-NAC compared with Gel and Gel-NAC. A mouse full-thickness skin wound model demonstrated that Gel-HP-NAC hydrogels improved the wound healing process as compared to the untreated group as proved by the increased wound closure rates and re-epithelialization. Histology of the biopsied tissues indicated more organized collagen deposits on the wounds treated with either Gel-HP-NAC or Gel-NAC than untreated wounds. Our results show that modification of NAC-containing hydrogels through methacrylate-containing polymers improved their wound healing properties, including blood-clotting, and demonstrate the potential of Gel-HP-NAC hydrogels for wound treatment and tissue regeneration.

Overcoming the protein corona in chitosan-based nanoparticles

Numerous properties of chitosan have led to its extensive use in the formulation of nanomaterials for drug delivery. However, the cationic surface of chitosan-based nanoparticles adsorbs proteins upon exposure to biological fluids, forming a phenomenon known as 'protein corona'. This causes several effects such as decreased bioavailability and limited in vivo clinical applications of chitosan nanoparticles. Understanding and overcoming the effects of protein adsorption on chitosan nanoparticles is key for drug delivery purposes. This review focuses on the strategies implemented to increase the stability of chitosan nanoparticles in the systemic circulation by averting the formation of protein corona and the limitations of PEGylation.

High Flexible and Broad Antibacterial Nanodressing Induces Complete Skin Repair with Angiogenic and Follicle Regeneration

Complete skin reconstruction is a hierarchically physiological assembly involving epidermis, dermis, vasculature, innervation, hair follicles, and sweat glands. Despite various wound dressings having been developed for skin regeneration, few works refer to the complete skin regeneration, particularly lacking for vasculatures and hair follicles. Herein, an instructive wound dressing that integrates the antibacterial property of quaternized chitin and the mechanical strength and biological multifunction of silk fibroin through layer-by-layer electrostatic self-assembly is designed and reported. The resultant dressings exhibit a nanofibrous structure ranging from 471.5 ± 212.1 to 756.9 ± 241.8 nm, suitable flexibility with tensile strength up to 4.47 ± 0.29 MPa, and broad-spectrum antibacterial activity against Escherichia coli and Staphylococcus aureus. More interestingly, the current dressing system remarkably accelerates in vivo vascular reconstruction within 15 days, and the number of regenerated hair follicles reaches up to 22 ± 4 mm-2, which is comparable to the normal tissue (27 ± 2 mm-2). Those crucial functions might originate from the combination between quaternized chitin and silk fibroin and the hierarchical structure of electrospun nanofiber. This work establishes an easy but effective pathway to design a multifunctional wound dressing for the complete skin regeneration.

Dipteran Carboxymethyl Chitosan as an Inexhaustible Derivative with a Potential Antiproliferative Activity in Hepatocellular Carcinoma Cells

Traditional folk therapies indicate that insects have diverse medicinal potentials. However, the therapeutic application of insect chitosan and its derivatives has not been explored. To investigate the application of chitosan and its derivatives, the carboxymethyl derivative of chitosan (CM-Ch) was extracted from two dipteran larvae species, Chrysomya albiceps and Sarcophaga aegyptiaca. The degree of deacetylation (DD) and CM-Ch functional groups were validated using Fourier-transform infrared (FTIR) spectroscopy analysis and proton nuclear magnetic resonance spectroscopy (¹H NMR), respectively. The molecular weight was estimated using MALDI-TOF MS analysis. The effect of CM-Ch on the morphology and proliferation of human liver HepG2 cancer cells was assessed. IC₅₀ of CM-Ch induced significant growth-inhibitory effects in HepG2 cells. CM-Ch treatment altered the morphology of HepG2 in a dose-dependent manner and induced apoptosis in a caspase-dependent manner. CM-Ch treatment showed no signs of toxicity, and no alterations in liver and kidney biochemical markers were observed in albino rats. A CM-Ch derivative from commercial crustacean chitosan was used to assess the efficacy of the insect-derived CM-Ch. The data presented here introduce insect CM-Ch as a promising, inexhaustible, safe derivative of chitosan with antitumor potential in liver cancer. This is the first report highlighting the anticancer activity of insect CM-Ch in hepatocellular carcinoma cells.

Polymeric Hydrogel Systems as Emerging Biomaterial Platforms to Enable Hemostasis and Wound Healing

Broad interest in developing new hemostatic technologies arises from unmet needs in mitigating uncontrolled hemorrhage in emergency, surgical, and battlefield settings. Although a variety of hemostats, sealants, and adhesives are available, development of ideal hemostatic compositions that offer a range of remarkable properties including capability to effectively and immediately manage bleeding, excellent mechanical properties, biocompatibility, biodegradability, antibacterial effect, and strong tissue adhesion properties, under wet and dynamic conditions, still remains a challenge. Benefiting from tunable mechanical properties, high porosity, biocompatibility, injectability and ease of handling, polymeric hydrogels with outstanding hemostatic properties have been receiving increasing attention over the past several years. In this review, after shedding light on hemostasis and wound healing processes, the most recent progresses in hydrogel systems engineered from natural and synthetic polymers for hemostatic applications are discussed based on a comprehensive literature review. Most studies described used in vivo models with accessible and compressible wounds to assess the hemostatic performance of hydrogels. The challenges that need to be tackled to accelerate the translation of these novel hemostatic hydrogel systems to clinical practice are emphasized and future directions for research in the field are presented.

Evidence Supporting the Safety of Pegylated Diethylaminoethyl-Chitosan Polymer as a Nanovector for Gene Therapy Applications

PURPOSE

Diethylaminoethyl-chitosan (DEAE-CH) is a derivative with excellent potential as a delivery vector for gene therapy applications. The aim of this study is to evaluate its toxicological profile for potential future clinical applications.

METHODS

An endotoxin-free chitosan (CH) modified with DEAE, folic acid (FA) and polyethylene glycol (PEG) was used to complex small interfering RNA (siRNA) and form nanoparticles (DEAE12-CH-PEG-FA2/siRNA). Based on the guidelines from the International Organization for Standardization (ISO), the American Society for Testing and Materials (ASTM), and the Nanotechnology Characterization Laboratory (NCL), we evaluated the effects of the interaction between these nanoparticles and blood components. In vitro screening assays such as hemolysis, hemagglutination, complement activation, platelet aggregation, coagulation times, cytokine production, and reactive species, such as nitric oxide (NO) and reactive oxygen species (ROS), were performed on erythrocytes, plasma, platelets, peripheral blood mononuclear cells (PBMC) and Raw 264.7 macrophages. Moreover, MTS and LDH assays on Raw 264.7 macrophages, PBMC and MG-63 cells were performed.

RESULTS

Our results show that a targeted theoretical plasma concentration (TPC) of DEAE12-CH-PEG-FA2/siRNA nanoparticles falls within the guidelines' thresholds: <1% hemolysis, 2.9% platelet aggregation, no complement activation, and no effect on coagulation times. ROS and NO production levels were comparable to controls. Cytokine secretion (TNF-α, IL-6, IL-4, and IL-10) was not affected by nanoparticles except for IL-1β and IL-8. Nanoparticles showed a slight agglutination. Cell viability was >70% for TPC in all cell types, although LDH levels were statistically significant in Raw 264.7 macrophages and PBMC after 24 and 48 h of incubation.

CONCLUSION

These DEAE12-CH-PEG-FA2/siRNA nanoparticles fulfill the existing ISO, ASTM and NCL guidelines' threshold criteria, and their low toxicity and blood biocompatibility warrant further investigation for potential clinical applications.