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

The Impact of the Methacrylation Process on the Usefulness of Chitosan as a Biomaterial Component for 3D Printing

Chitosan is a very promising material for tissue model printing. It is also known that the introduction of chemical modifications to the structure of the material in the form of methacrylate groups makes it very attractive for application in the bioprinting of tissue models. The aim of this work is to study the characteristics of biomaterials containing chitosan (BCH) and its methacrylated equivalent (BCM) in order to identify differences in their usefulness in 3D bioprinting technology. It has been shown that the BCM material containing methacrylic chitosan is three times more viscous than its non-methacrylated BCH counterpart. Additionally, the BCM material is characterized by stability in a larger range of stresses, as well as better printability, resolution, and fiber stability. The BCM material has higher mechanical parameters, both mechanical strength and Young's modulus, than the BCH material. Both materials are ideal for bioprinting, but BCM has unique rheological properties and significant mechanical resistance. In addition, biological tests have shown that the addition of chitosan to biomaterials increases cell proliferation, particularly in 3D-printed models. Moreover, modification in the form of methacrylation encourages reduced toxicity of the biomaterial in 3D constructs. Our investigation demonstrates the suitability of a chitosan-enhanced biomaterial, specifically methacrylate-treated, for application in tissue engineering, and particularly for tissues requiring resistance to high stress, i.e., vascular or cartilage models.

Stem Cell-Derived Nanovesicles Embedded in Dual-Layered Hydrogel for Programmed ROS Regulation and Comprehensive Tissue Regeneration in Burn Wound Healing

Burn wounds often bring high risks of delayed healing process and even death. Reactive oxygen species (ROS) play a crucial role in burn wound repair. However, the dynamic process in wound healing requires both the generation of ROS to inhibit bacteria and the subsequent reduction of ROS levels to initiate and promote tissue regeneration, which calls for a more intelligent ROS regulation dressing system. Hence, a dual-layered hydrogel (Dual-Gel) tailored to the process of burn wound repair is designed: the inner layer hydrogel (Gel 2) first responds to bacterial hyaluronidase (Hyal) to deliver aggregation-induced emission photosensitizer functionalized adipose-derived stem cell nanovesicles, which generate ROS upon light irradiation to eliminate bacteria; then the outer layer hydrogel (Gel 1) continuously starts a long-lasting consumption of excess ROS at the wound site to accelerate tissue regeneration. Simultaneously, the stem cell nanovesicles trapped in the burns wound also provide nutrients and mobilize neighboring tissues to thoroughly assist in inflammation regulation, cell proliferation, migration, and angiogenesis. In summary, this study develops an intelligent treatment approach on burn wounds by programmatically regulating ROS and facilitating comprehensive wound tissue repair.

Chitosan-Based Hydrogels as Antibacterial/Antioxidant/Anti-Inflammation Multifunctional Dressings for Chronic Wound Healing

Due to repeated microbial infection, persistent inflammation, excessive oxidative stress, and cell dysfunction, chronic wounds are difficult to heal, posing a serious threat to public health. Therefore, developing multifunctional wound dressings that can regulate the complex microenvironment of chronic wounds and enhance cellular function holds great significance. Recently, chitosan has emerged as a promising biopolymer for wound healing due to its excellent biocompatibility, biodegradability, and versatile bioactivity. The aim of this review is to provide a comprehensive understanding of the mechanisms of delayed chronic wound healing and discuss the healing-promoting properties of chitosan and its derivatives, such as good biocompatibility, antibacterial activity, hemostatic capacity, and the ability to promote tissue regeneration. On this basis, the potential applications of chitosan-based hydrogels are summarized in chronic wound healing, including providing a suitable microenvironment, eliminating bacterial infections, promoting hemostasis, inhibiting chronic inflammation, alleviating oxidative stress, and promoting tissue regeneration. In addition, the concerns and perspectives for the clinical application of chitosan-based hydrogels are also discussed.

Water-Induced Expanded Bilayer Vascular Graft with Good Hemocompatibility and Biocompatibility

Shape memory polymer (SMP) vascular grafts are promising interventional vascular grafts for cardiovascular disease (CAD) treatment; However, hemocompatibility and biocompatibility, which are the critical issues for the SMP vascular grafts, are not systematically concerned. Furthermore, the water-induced SMP grafts are more convenient and safer than the thermally induced ones in case of the bioapplication. Herein, in this work, the new water-induced expanded bilayer vascular graft with the inner layer of crosslinked poly(ε-caprolactone) (cPCL) and the outer layer of water-induced SMP of regenerated chitosan/polyvinyl alcohol (RCS/PVA) are prepared by hot pressing and programming approaches. The results show that the inner and outer layer surfaces of the prepared grafts are smooth, and they exhibit good interfacial interaction properties. The bilayer grafts show good mechanical properties and can be expanded in water with a diameter expansion of ≈30%. When compared with commercial expanded polytetrafluoroethylene (ePTFE), the bilayer graft shows better hemocompatibility (platelet adhesion, hemolysis rate, various clotting times, and plasma recalcification time (PRT)) and in vitro and in vivo biocompatibility, which thus is a promising material for the vascular graft.

Bilirubin/morin self-assembled nanoparticle-engulfed collagen/polyvinyl alcohol hydrogel accelerates chronic diabetic wound healing by modulating inflammation and ameliorating oxidative stress

Chronic diabetic wounds pose a serious threat to human health and safety because of their refractory nature and high recurrence rates. The formation of refractory wounds is associated with wound microenvironmental factors such as increased expression of proinflammatory factors and oxidative stress. Bilirubin is a potent endogenous antioxidant, and morin is a naturally active substance that possesses anti-inflammatory and antioxidant effects. Both hold the potential for diabetic wound treatment by intervening in pathological processes. In this study, we developed bilirubin/morin-based carrier-free nanoparticles (BMn) to treat chronic diabetic wounds. In vitro studies showed that BMn could effectively scavenge overproduced reactive oxygen species and suppress elevated inflammation, thereby exerting a protective effect. BMn was then loaded into a collagen/polyvinyl alcohol gel (BMn@G) for an in vivo study to maintain a moist environment for the skin and convenient biomedical applications. BMn@G exhibits excellent mechanical properties, water retention capabilities, and in vivo safety. In type I diabetic mice, BMn@G elevated the expression of the anti-inflammatory factor IL-10 and concurrently diminished the expression of the proinflammatory factor TNF-α in the tissues surrounding the wounds. Furthermore, BMn@G efficiently mediated macrophage polarization from the M1-type to the M2-type, thereby fostering anti-inflammatory effects. Additionally, BMn@G facilitated the conversion of type III collagen fiber bundles to type I collagen fiber bundles, resulting in a more mature collagen fiber structure. This study provides a promising therapeutic alternative for diabetic wound healing.

Hydrogel Based on Riclin Cross-Linked with Polyethylene Glycol Diglycidyl Ether as a Soft Filler for Tissue Engineering

Hydrogels composed of natural polysaccharides have been widely used as filling materials, with a growing interest in medical cosmetology and skin care. However, conventional commercial dermal fillers still have limitations, particularly in terms of mechanical performance and durability in vivo. In this study, a novel injectable and implantable hydrogel with adjustable characteristics was prepared from succinoglycan riclin by introducing PEG diglycidyl ether as a cross-linker. FTIR spectra confirmed the cross-linking reaction. The riclin hydrogels exhibited shear-thinning behavior, excellent mechanical properties, and cytocompatibility through in vitro experiments. Furthermore, when compared with subcutaneous injection of a commercial hyaluronic acid hydrogel, the riclin hydrogels showed enhanced persistence and biocompatibility in Balb/c mice after 16 weeks. These results demonstrate the great potential of the riclin-based hydrogel as an alternative to conventional commercial soft tissue fillers.

Ho(III)-coordination Complex: Fluorescence Performances and Combined with Captopril-Hydrogels against Glioma

In this study, a novel dinuclear lanthanide complex, denoted as [Ho2(L)2(acac)2(CH3OH)2]·CH3OH (1) (where H2L is 2-[((4-methyl)-2-(carboxyl)-imino)]methyl]-8-hydroxyquinoline, and Hacac is acetylacetonate), was successfully synthesized and characterized using single-crystal and elemental analysis, with the auxiliary ligand β-diketonate and the 8-hydroxyquinoline Schiff base derivative serving as the foundation. Through ligand-to-metal charge transfer, Compound 1 demonstrated remarkable green fluorescence properties, showcasing potential applications in green fluorescence materials and fluorescence sensing. Additionally, Hyaluronic Acid (HA)/Carboxymethyl Chitosan (CMCS) hydrogels were synthesized through a chemical method. Utilizing captopril as a drug model, a novel metal gel granule of captopril was developed and assessed for its inhibitory activity against glioma cells. Molecular docking simulations revealed that only the methanol group in the Ho complex could contribute a polar atom for the formation of binding interactions.

Strategies for Development of Synthetic Heart Valve Tissue Engineering Scaffolds

The current clinical solutions, including mechanical and bioprosthetic valves for valvular heart diseases, are plagued by coagulation, calcification, nondurability, and the inability to grow with patients. The tissue engineering approach attempts to resolve these shortcomings by producing heart valve scaffolds that may deliver patients a life-long solution. Heart valve scaffolds serve as a three-dimensional support structure made of biocompatible materials that provide adequate porosity for cell infiltration, and nutrient and waste transport, sponsor cell adhesion, proliferation, and differentiation, and allow for extracellular matrix production that together contributes to the generation of functional neotissue. The foundation of successful heart valve tissue engineering is replicating native heart valve architecture, mechanics, and cellular attributes through appropriate biomaterials and scaffold designs. This article reviews biomaterials, the fabrication of heart valve scaffolds, and their in-vitro and in-vivo evaluations applied for heart valve tissue engineering.

Chitosan-polyethylene oxide/clay-alginate nanofiber hydrogel scaffold for bone tissue engineering: Preparation, physical characterization, and biomimetic mineralization

This study aimed to prepare a novel organic-mineral nanofiber/hydrogel of chitosan-polyethylene oxide (CS-PEO)/nanoclay-alginate (NC-ALG). The effects of NC particles on the mineralization and biocompatibility of the scaffold were investigated. A layer-by-layer scaffold composed of CS-PEO and NC-ALG was prepared. The morphological properties, swelling, biodegradation, and mechanical behaviors of the scaffolds were evaluated. Furthermore, scaffolds were characterized by the Fourier Transform Infrared (FTIR), the Field Emission Scanning Electron Microscope (FE-SEM), and X-Ray Diffraction (XRD) techniques. Bone-like apatite formation ability of the scaffolds was determined by the mineralization test in a simulated body fluid (M-SBF). In addition, the crystalline phase of bone-like apatite precipitates was investigated by XRD analysis. The cell compatibility of the scaffolds was also studied with osteoblastic cell line MC3T3-E1 by MTT assay. Notably, the incorporation of NC particles in CS-PEO/ALG scaffolds is suitable for bone tissue regeneration which enhances bone-like apatite formation. Further, the hemolysis and MTT assays demonstrated that CS-PEO/NC-ALG scaffold was compatible and safe for MC3T3 cells.

Injectable Hydrogel Containing Cowpea Mosaic Virus Nanoparticles Prevents Colon Cancer Growth

Despite advances in laparoscopic surgery combined with neoadjuvant and adjuvant therapy, colon cancer management remains challenging in oncology. Recurrence of cancerous tissue locally or in distant organs (metastasis) is the major problem in colon cancer management. Vaccines and immunotherapies hold promise in preventing cancer recurrence through stimulation of the immune system. We and others have shown that nanoparticles from plant viruses, such as cowpea mosaic virus (CPMV) nanoparticles, are potent immune adjuvants for cancer vaccines and serve as immunostimulatory agents in the treatment or prevention of tumors. While being noninfectious toward mammals, CPMV activates the innate immune system through recognition by pattern recognition receptors (PRRs). While the particulate structure of CPMV is essential for prominent immune activation, the proteinaceous architecture makes CPMV subject to degradation in vivo; thus, CPMV immunotherapy requires repeated injections for optimal outcome. Frequent intraperitoneal (IP) injections however are not optimal from a clinical point of view and can worsen the patient's quality of life due to the hospitalization required for IP administration. To overcome the need for repeated IP injections, we loaded CPMV nanoparticles in injectable chitosan/glycerophosphate (GP) hydrogel formulations, characterized their slow-release potential, and assessed the antitumor preventative efficacy of CPMV-in-hydrogel single dose versus soluble CPMV (single and prime-boost administration). Using fluorescently labeled CPMV-in-hydrogel formulations, in vivo release data indicated that single IP injection of the hydrogel formulation yielded a gel depot that supplied intact CPMV over the study period of 3 weeks, while soluble CPMV lasted only for one week. IP administration of the CPMV-in-hydrogel formulation boosted with soluble CPMV for combined immediate and sustained immune activation significantly inhibited colon cancer growth after CT26 IP challenge in BALB/c mice. The observed antitumor efficacy suggests that CPMV can be formulated in a chitosan/GP hydrogel to achieve prolonged immunostimulatory effects as single-dose immunotherapy against colon cancer recurrence. The present findings illustrate the potential of injectable hydrogel technology to accommodate plant virus nanoparticles to boost the translational development of effective antitumor immunotherapies.

Healing effect of carboxymethyl chitosan-plantamajoside hydrogel on burn wound skin

BACKGROUND

It is known that hydrogels based on carboxymethyl chitosan (CMCS) have properties controling microbial growth, reducing inflammatory cell infiltration, and promoting collagen deposition. Plantamajoside (PMS), a natural Chinese herbal medicine with biological activity, has the properties of reducing inflammation, anti-oxidation, and promoting wound healing. However, the effects of carboxymethyl chitosan/plantamajoside hydrogel on partial thickness burn wounds remain unclear.

METHODS

The healing effect of carboxymethyl chitosan/plantamajoside hydrogel was evaluated by in vitro cell viability assay, cell migration assay, and further evaluated in a rat model of partial-thickness burn wounds.

RESULTS

The hydrogels were highly porous with a pore size of about 250 μm, and these pores were interconnected. After adding plantamajoside, a dense microstructure was further formed. The hydrogels containing 0.25% plantamajoside significantly increased the viability and migration of L929 cells (P < 0.05). Carboxymethyl chitosan/plantamajoside hydrogel significantly improved wound healing, granulation tissue proliferation and re-epithelialization, and promoted collagen deposition (P < 0.05). Carboxymethyl chitosan/plantamajoside hydrogel also significantly decreased IL (interleukin)-1β, IL-6 and TNF-α expression, and increased IL-10 expression (P < 0.05). Furthermore, carboxymethyl chitosan/plantamajoside hydrogel significantly promoted the expression levels of VEGF, CD31, α-SMA (α-smooth muscle actin) and collagen III, and reduced the expression level of collagen Ⅰ (P < 0.05). Our data suggest that carboxymethyl chitosan/plantamajoside hydrogel promotes burn wound healing by accelerating angiogenesis and collagen deposition and reducing the inflammatory response.

Carboxymethyl chitosan-based electrospun nanofibers with high citral-loading for potential anti-infection wound dressings

As a natural antibacterial agent with pleasant fragrance, citral possesses low aqueous solubility. To improve citral loading in hydrophilic nanofiber, Pickering emulsion electrospinning strategy was proposed for anti-infection dressing development. The in-situ aggerated β-cyclodextrin-citral inclusion complex particles (βCPs) were used as emulsion stabilizers, while citral and carboxymethyl chitosan (CMCS)/polyvinyl alcohol (PVA) mixed solutions were used as the inner "dispersed oil phase" and outer "continuous water phase", respectively. The results of electronic microscope investigation shown βCPs possessed regular cube appearances with a size of 5.5 ± 2.2 μm, which might improve the emulsion storage stability based on visual investigation. Moreover, randomly oriented and bead-on-string nanofibers with βCPs uniformly distributed could be obtained under optimized compositions and electrospinning parameters. Despite volatilization during electrospinning, nanofibers with high citral loading possessed good antibacterial performance against Staphylococcus aureus and Escherichia coli. In vitro hemolysis test indicated that nanofibers were hemocompatible. In addition, both fiber matrix and citral could promote the proliferation of mouse fibroblast cells. And the permeability of the fibers was adjustable. Thus, CMCS/PVA/βCPs/citral nanofibers could potentially protect wound from infection. In summary, CMCS/PVA/βCPs/citral nanofibers seemed to be promising alternatives to conventional wound dressings.

Enhanced hydrophilicity and anticoagulation of polysulfone materials modified via dihydroxypropyl, sulfonic groups and chitosan

A novel modified polysulfone (PSF) is successfully prepared for hemodialysis by grafting with a well-defined heparin-like polymer, sulfonated dihydroxypropyl chitosan (SDHPCS), which is obtained in proper sequence via alkalization of chitosan, etherification and sulfonation. PSF is modified via chloroacetyl chloride, and then, the chloroacylated polysulfone (CAPSF) with pristine PSF is transformed into CAPSF/PSF blend membrane via the phase inversion, followed introducing amino group into CAPSF on the surface and taking glutaraldehyde as bridge between modified PSF membrane and SDHPCS. The result of ¹H NMR spectrum of prepared CAPSF indicates that the degree of the substitution of chloroacetyl group. The SEM, EDS mapping, FTIR and XPS show that SDHPCS-g-PSF membranes are successfully prepared. The hydrophilicity of the membrane modified by SDHPCS is improved obviously, and the contact angle remarkably reduced from 87 ° to below 45°, exhibiting much better hydrophilicity. The hemocompatibility characterizations including BSA adsorption, Plasma recalcification time (PRT), hemolysis ratio (HR), activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT) also certificates that SDHPCS-g-PSF possesses lower BSA adsorption and enhanced blood compatibility.

Chitosan as an Underrated Polymer in Modern Tissue Engineering

Chitosan is one of the most well-known and characterized materials applied in tissue engineering. Due to its unique chemical, biological and physical properties chitosan is frequently used as the main component in a variety of biomaterials such as membranes, scaffolds, drug carriers, hydrogels and, lastly, as a component of bio-ink dedicated to medical applications. Chitosan's chemical structure and presence of active chemical groups allow for modification for tailoring material to meet specific requirements according to intended use such as adequate endurance, mechanical properties or biodegradability time. Chitosan can be blended with natural (gelatin, hyaluronic acid, collagen, silk, alginate, agarose, starch, cellulose, carbon nanotubes, natural rubber latex, κ-carrageenan) and synthetic (PVA, PEO, PVP, PNIPPAm PCL, PLA, PLLA, PAA) polymers as well as with other promising materials such as aloe vera, silica, MMt and many more. Chitosan has several derivates: carboxymethylated, acylated, quaternary ammonium, thiolated, and grafted chitosan. Its versatility and comprehensiveness are confirming by further chitosan utilization as a leading constituent of innovative bio-inks applied for tissue engineering. This review examines all the aspects described above, as well as is focusing on a novel application of chitosan and its modifications, including the 3D bioprinting technique which shows great potential among other techniques applied to biomaterials fabrication.

Alendronate-Decorated Nanoparticles as Bone-Targeted Alendronate Carriers for Potential Osteoporosis Treatment

Osteoporosis is a skeletal disorder characterized by a low bone mass and density. Alendronate (Alen), a second-generation bisphosphonate drug, was indicated as the first-line regimen for the treatment of osteoporosis. However, the use of Alen has been limited due to its low bioavailability and gastrointestinal side effects. Herein, Alen-decorated nanoparticles were prepared through ionic cross-linking between poly (lactic-co-glycolic acid), β-cyclodextrin-modified chitosan (PLGA-CS-CD), and Alen-modified alginate (ALG-Alen) for Alen loading and bone-targeted delivery. Alen was selected as a therapeutic drug and a bone-targeting ligand. The nanoparticles have negatively charged surfaces, and sustained release of Alen from the nanoparticles can be observed. Cytotoxicity detected using cell counting kit-8 (CCK-8) assay and lactate dehydrogenase release test on MC3T3 cells showed that the nanoparticles had good cytocompatibility. A hemolysis test showed that the hemolysis ratios of nanoparticles were <5%, indicating that the nanoparticles had no significant hemolysis effect. Moreover, the Alen-decorated nanoparticles exhibited enhanced binding affinity to the hydroxyapatite (HAp) disks compared with that of nanoparticles without Alen modification. Thus, the Alen-decorated nanoparticles might be developed as promising bone-targeted carriers for the treatment of osteoporosis.

Hemostatic performance of chitosan-based hydrogel and its study on biodistribution and biodegradability in rats

Hemostasis is of great significance regardless of the smooth operation or postoperative recovery. Therefore, it is urgent to develop a hemostatic material with excellent biodegradability and biocompatibility. It is well known that both carboxymethyl chitosan and hyaluronic acid with biodegradability and biocompatibility have wound healing promoting property. Here, a degradable chitosan-based hydrogel was prepared based on carboxymethyl chitosan and cross-linked by oxidized hyaluronic acid. The hemostatic performance of the hydrogel in rat liver resection injury was evaluated which results showed that the hydrogel exhibited comparable hemostatic properties compared with Fibrin Sealant. In addition, the hydrogel proved to be rapidly absorbed by the body without significant accumulation in vivo, demonstrating good biodegradability and biocompatibility. The overall results suggested the hydrogel will be a promising hemostatic hydrogel for controlling bleeding.

Development of an albumin decorated lipid-polymer hybrid nanoparticle for simultaneous delivery of methotrexate and conferone to cancer cells

Aiming to simultaneous target of methotrexate (MTX), as folate antagonist, and conferone (CON) in various cancer cells, the newly lipid/polymer hybrid nanoparticle containing an albumin targeted succinylchitosan shell and lipoid bilayer core composed of hydrogenated soy phosphatidylcholine and cholesterol was synthesized. The covalently conjugating albumin to the external surface of chitosan was accomplished using N-(3-Dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride and N- hydroxyl succinimide as an activating carboxylic group, and nanoliposomes were fabricated via thin film hydration-sonication method. The molecular structure of MTX@CON-targeted lipid/polymer hybrid nanoparticle (MTX@CON-TLPN) were characterized using FTIR spectroscopy, ¹H NMR, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The newly nanoparticle with high encapsulation efficiency (85.12%, and 78.4%), acceptable loading capacity (9.8% and 4.6% for MTX and CON) and the stimuli responsiveness drug release behavior in simulated physiologic tumor tissue condition (pH 5.4, 40 °C) was successfully synthetized in the spherical shape with mean average size of approximately 290 nm and ζ-potential of +21 mv. The enhanced efficiency of the targeted nanoparticle was further confirmed using MTT endpoints, cell cycle modulation, apoptosis assessment, and cellular internalization assessments. Collectively, these findings establish the utility of our newly prepared nanoparticle for simultaneous delivery of multiple anti-cancer drugs.

Biocompatibility and mechanical properties evaluation of chitosan films containing an N-acylhydrazonic derivative

The N-acylhydrazone subunit is considered a privileged structure in medicinal chemistry for its importance in pharmaceutical research. Also, alternative methods to deliver these molecules have a great pharmaceutical interest. Therefore, the objective of this work was to encapsulate JR19, an N-acyl hydrazone subunit, into chitosan films and evaluate several properties relevant for transdermal delivery, including biocompatibility using in vitro tests. CHI + JR19 film demonstrates greater strength, flexibility, water absorption capacity, low contact angle and higher surface roughness when compared to CHI. Agar diffusion and 3-(4,5-dimethyl)-2,5-diphenyl tetrazolium bromide (MTT) assay show the absence of cytotoxicity and the higher cell viability for CHI + JR19 films. Therefore, the addition of JR19 in the system positively influenced mechanical properties and granted better compatibility with biological environments, showing the potential to treat skin inflammation.

Influence of chitosan average molecular weight on degradation and stability of electrodeposited conduits

Tubular chitosan-based hydrogels, obtained in an electrodeposition process, are subject of degradation and stability studies. The implants are prepared from polymer with different average molecular weight. This approach allows fabricating structures that vary in mass and wall thickness. The obtained implants are incubated in phosphate buffered solution (pH 7.4) with or without lysozyme up to 56 days at 37 °C. Subsequently, chemical, physical as well as mechanical properties of implants are evaluated. Although the initial physicomechanical properties are different, they change upon incubation and remain similar over its period. Finally, in vitro biocompatibility of implants is proven after assessing their action towards mHippoE-18 embryonic hippocampal cells and THP1-XBlue™ monocytes. Since dimensions of nerves and the gap length differ across the body and injury, respectively, the possibility to control properties of chitosan applied gives a tool to prepare implants with wall thickness adjusted to the specific peripheral nerve injury case.

Bioresorbable hydrogels prepared by photo-initiated crosslinking of diacrylated PTMC-PEG-PTMC triblock copolymers as potential carrier of antitumor drugs

PTMC-PEG-PTMC triblock copolymers were prepared by ring-opening polymerization of trimethylene carbonate (TMC) in the presence of dihydroxylated poly(ethylene glycol) (PEG) with Mn of 6000 and 10,000 as macro-initiator. The copolymers with different PTMC block Lengths and the two PEGs were end functionalized with acryloyl chloride. The resulting diacrylated PEG-PTMC-DA and PEG-DA were characterized by using NMR, GPC and DSC. The degree of substitution of end groups varied from 50.0 to 65.1%. Hydrogels were prepared by photo-crosslinking PEG-PTMC-DA and PEG-DA in aqueous solution using a water soluble photo-initiator under visible light irradiation. The effects of PTMC and PEG block lengths and degree of substitution on the swelling and weight loss of hydrogels were determined. Higher degree of substitution leads to higher crosslinking density, and thus to lower degree of swelling and weight loss. Similarly, higher PTMC block length also leads to lower degree of swelling and weight loss. Freeze dried hydrogels exhibit a highly porous structure with pore sizes from 20 to 100 µm.

The biocompatibility of hydrogels was evaluated by MTT assay, hemolysis test, and dynamic clotting time measurements. Results show that the various hydrogels present outstanding cyto- and hemo-compatibility. Doxorubicin was taken as a model drug to evaluate the potential of PEG-PTMC-DA and PEG-DA hydrogels as drug carrier. An initial burst release was observed in all cases, followed by slower release up to more than 90%. The release rate is strongly dependent on the degree of swelling. The higher the degree of swelling, the faster the release rate. Finally, the effect of drug loaded hydrogels on SKBR-3 tumor cells was evaluated in comparison with free drug. Similar cyto-toxicity was obtained for drug loaded hydrogels and free drug at comparable drug concentrations. Therefore, injectable PEG-PTMC-DA hydrogels with outstanding biocompatibility and drug release properties could be most promising as bioresorbable carrier of hydrophilic drugs.