Design and fabrication of hybrid triple-responsive κ-carrageenan-based nanospheres for controlled drug delivery

Magnetic graphene oxide functionalized alginate-g-poly(2-hydroxypropylmethacrylamide) nanoplatform for near-infrared light/pH/magnetic field-sensitive drug release and chemo/phototherapy

Multifunctional nanoplatforms developed from natural polymers and graphene oxide (GO) with enhanced biological/physicochemical features have recently attracted attention in the biomedical field. Herein, a new multifunctional near-infrared (NIR) light-, pH- and magnetic field-sensitive hybrid nanoplatform (mGO@AL-g-PHPM@ICG/EP) is developed by combining iron oxide decorated graphene oxide nanosheets (mGO) and poly(2-hydroxypropylmethacrylamide) grafted alginate (AL-g-PHPM) copolymer loaded with indocyanine green (ICG) and etoposide (EP) for chemo/phototherapy. The functional groups, specific crystal structure, size, morphology, and thermal stability of the nanoplatform were fully characterized by XRD, UV, FTIR, AFM/TEM/FE-SEM, VSM, DSC/TG, and BET analyses. In this platform, the mGO and ICG, as phototherapeutic agents, demonstrate excellent thermal effects and singlet oxygen production under NIR-light (808 nm) irradiation. The XRD and DSC analysis confirmed the amorphous state of the ICG/EP in the nanoparticles. In vitro photothermal tests proved that the mGO@AL-g-PHPM@ICG/EP nanoparticles had outstanding light stability and photothermal conversion ability. The in vitro release profiles presented NIR light-, pH- and magnetic field-controlled EP/ICG release behaviors. In vitro experiments demonstrated the excellent antitumor activity of the mGO@AL-g-PHPM@ICG/EP against H1299 tumor cells under NIR laser. Benefiting from its low-cost, facile preparation, and good dual-modal therapy, the mGO@AL-g-PHPM@ICG/EP nanoplatform holds great promise in multi-stimuli-sensitive drug delivery and chemo/phototherapy.

Carrageenan as a macromolecular crowding agent in human umbilical cord derived mesenchymal stromal cell culture

Cell sheet tissue engineering requires prolonged in vitro culture for the development of implantable devices. Unfortunately, lengthy in vitro culture is associated with cell phenotype loss and substantially higher cost of goods, which collectively hinder clinical translation and commercialisation of tissue engineered medicines. Although macromolecular crowding has been shown to enhance and accelerate extracellular matrix deposition, whilst maintaining cellular phenotype, the optimal macromolecular crowding agent still remains elusive. Herein, we evaluated the biophysical properties of seven different carrageenan molecules at five different concentrations and their effect on human umbilical cord-derived mesenchymal stromal cell morphology, viability, metabolic activity, proliferation, extracellular matrix deposition and surface marker expression. All types of carrageenan (CR) assessed demonstrated a hydrodynamic radius increase as a function of increasing concentration; high polydispersity; and negative charge. Two iota CRs were excluded from further analysis due to poor solubility in cell culture. Among the remaining five carrageenans, the lambda medium viscosity type at concentrations of 10 and 50 μg/ml did not affect cell morphology, viability, metabolic activity, proliferation and expression of surface markers and significantly increased the deposition of collagen types I, III and IV, fibronectin and laminin. Our data highlight the potential of lambda medium viscosity carrageenan as a macromolecular crowding agent for the accelerated development of functional tissue engineered medicines.

Design and development of pH-responsive alginate-based nanogel carriers for etoposide delivery

Recently, pH-responsive nanogels are playing progressively important roles in cancer treatment. The present study focuses on designing and developing pH-responsive alginate-based nanogels to achieve a controlled release of etoposide (Et) while enhancing its hydrophilicity. Alginate (ALG) is grafted with 2-hydroxypropyl methacrylamide (HPMA) through a microwave-supported method, and the chemical structure of the graft copolymer (ALG-g-PHPMA) was verified by 1H/13C NMR and FTIR techniques. The ALG-g-PHPMA and anticancer drug-loaded ALG-g-PHPMA@Et nanogels were obtained using an emulsion method, and their structures were characterized through FTIR, TG/DSC, AFM/TEM, BET, and DLS analyses. The ALG-g-PHPMA nanogels demonstrated a good drug encapsulation efficiency (79.60 %), displaying a pH-dependent release profile and an in vitro accelerated release of Et compared to the ALG nanogels. Thermal and BET analyses revealed enhanced stability, surface area, and porosity volume of the alginate nanogels. The grafting of PHPMA chains onto alginate altered the surface topology of the ALG nanogels, resulting in lower surface roughness. Furthermore, cytotoxicity tests showed the high biocompatibility of the ALG-g-PHPMA copolymer and its nanogels. The ALG-g-PHPMA@Et nanogels exhibited a higher anticancer effect on lung cancer (H1299) cells than free etoposide. These results suggest that the ALG-g-PHPMA nanogels can be applied as a pH-dependent nanoplatform for delivering anticancer drugs.

Plant-Derived Biomaterials and Their Potential in Cardiac Tissue Repair

Cardiovascular disease remains the leading cause of mortality worldwide. The inability of cardiac tissue to regenerate after an infarction results in scar tissue formation, leading to cardiac dysfunction. Therefore, cardiac repair has always been a popular research topic. Recent advances in tissue engineering and regenerative medicine offer promising solutions combining stem cells and biomaterials to construct tissue substitutes that could have functions similar to healthy cardiac tissue. Among these biomaterials, plant-derived biomaterials show great promise in supporting cell growth due to their inherent biocompatibility, biodegradability, and mechanical stability. More importantly, plant-derived materials have reduced immunogenic properties compared to popular animal-derived materials (e.g., collagen and gelatin). In addition, they also offer improved wettability compared to synthetic materials. To date, limited literature is available to systemically summarize the progression of plant-derived biomaterials in cardiac tissue repair. Herein, this paper highlights the most common plant-derived biomaterials from both land and marine plants. The beneficial properties of these materials for tissue repair are further discussed. More importantly, the applications of plant-derived biomaterials in cardiac tissue engineering, including tissue-engineered scaffolds, bioink in 3D biofabrication, delivery vehicles, and bioactive molecules, are also summarized using the latest preclinical and clinical examples.

Recent advances in cellulose, pectin, carrageenan and alginate-based oral drug delivery systems

Polymers-based drug delivery systems constitute one of the highly explored thrust areas in the field of the medicinal and pharmaceutical industries. In the past years, the properties of polymers have been modified in context to their solubility, release kinetics, targeted action site, absorption, and therapeutic efficacy. Despite the availability of diverse synthetic polymers for the bioavailability enhancement of drugs, the use of natural polymers is still highly recommended due to their easy availability, accessibility, and non-toxicity. The aim of the review is to provide the available literature of the last five years on oral drug delivery systems based on four natural polymers i.e., cellulose, pectin, carrageenan, and alginate in a concise and tabulated manner. In this review, most of the information is in tabulated form to provide easy accessibility to the reader. The data related to active pharmaceutical ingredients and supported components in different formulations of the mentioned polymers have been made available.

Chemical modification of κ-carrageenan with poly(2-hydroxypropylmethacrylamide) through microwave induced graft copolymerization: Characterization and swelling features

In the last decade, interest in the development of new graft copolymers based on natural polysaccharides has grown remarkably due to their potential applications in the wastewater treatment, biomedical, nanomedicine, and pharmaceutical fields. Herein, a novel graft copolymer of κ-carrageenan with poly(2-hydroxypropylmethacrylamide) (κ-Crg-g-PHPMA) was synthesized using a 'microwave induced' technique. The synthesized novel graft copolymer has been well characterized in terms of FTIR, ¹³C NMR, molecular weight determination, TG, DSC, XRD, SEM, and elemental analyses, taking κ-carrageenan as a reference. The graft copolymers' swelling characteristics were investigated at pH 1.2 and 7.4. The results of swelling studies displayed that the incorporation of PHPMA groups on κ-Crg provides increasing hydrophilicity. The effect of PHPMA percentage in the graft copolymers and pH of the medium on the swelling percentage was studied and the findings exhibited that swelling ability increased with the increment in PHPMA percentage and pH of the medium. The best swelling percentage was attained at pH = 7.4 and a grafting percentage of 81 % reaching 1007 % at the end of 240 min. Moreover, cytotoxicity of the synthesized κ-Crg-g-PHPMA copolymer was assessed on the L929 fibroblast cell line and obtained to be non-toxic.

Recent advances in exploiting carrageenans as a versatile functional material for promising biomedical applications

Carrageenans are a group of biopolymers widely found in red seaweeds. Commercial carrageenans have been traditionally used as emulsifiers, stabilizers, and thickening and gelling agents in food products. Carrageenans are regarded as bioactive polysaccharides with disease-modifying and microbiota-modulating activities. Novel biomedical applications of carrageenans as biocompatible functional materials for fabricating hydrogels and nanostructures, including carbon dots, nanoparticles, and nanofibers, have been increasingly exploited. In this review, we describe the unique structural characteristics of carrageenans and their functional relevance. We summarize salient physicochemical features, including thixotropic and shear-thinning properties, of carrageenans. Recent results from clinical trials in which carrageenans were applied as both antiviral and antitumor agents and functional materials are discussed. We also highlight the most recent advances in the development of carrageenan-based targeted drug delivery systems with various pharmaceutical formulations. Promising applications of carrageenans as a bioink material for 3D printing in tissue engineering and regenerative medicine are systematically evaluated. We envisage some key hurdles and challenges in the commercialization of carrageenans as a versatile material for clinical practice. This comprehensive review of the intimate relationships among the structural features, unique rheological properties, and biofunctionality of carrageenans will provide novel insights into their biomedicine application potential.