Effects of amphiphilic chitosan-g-poly(ε-caprolactone) polymer additives on paclitaxel release from drug eluting implants

Lignin, lipid, protein, hyaluronic acid, starch, cellulose, gum, pectin, alginate and chitosan-based nanomaterials for cancer nanotherapy: Challenges and opportunities

Although nanotechnology-driven drug delivery systems are relatively new, they are rapidly evolving since the nanomaterials are deployed as effective means of diagnosis and delivery of assorted therapeutic agents to targeted intracellular sites in a controlled release manner. Nanomedicine and nanoparticulate drug delivery systems are rapidly developing as they play crucial roles in the development of therapeutic strategies for various types of cancer and malignancy. Nevertheless, high costs, associated toxicity and production of complexities are some of the critical barriers for their applications. Green nanomedicines have continually been improved as one of the viable approaches towards tumor drug delivery, thus making a notable impact on which considerably affect cancer treatment. In this regard, the utilization of natural and renewable feedstocks as a starting point for the fabrication of nanosystems can considerably contribute to the development of green nanomedicines. Nanostructures and biopolymers derived from natural and biorenewable resources such as proteins, lipids, lignin, hyaluronic acid, starch, cellulose, gum, pectin, alginate, and chitosan play vital roles in the development of cancer nanotherapy, imaging and management. This review uncovers recent investigations on diverse nanoarchitectures fabricated from natural and renewable feedstocks for the controlled/sustained and targeted drug/gene delivery systems against cancers including an outlook on some of the scientific challenges and opportunities in this field. Various important natural biopolymers and nanomaterials for cancer nanotherapy are covered and the scientific challenges and opportunities in this field are reviewed.

Amphiphilic copolymers in biomedical applications: Synthesis routes and property control

The request of new materials, matching strict requirements to be applied in precision and patient-specific medicine, is pushing for the synthesis of more and more complex block copolymers. Amphiphilic block copolymers are emerging in the biomedical field due to their great potential in terms of stimuli responsiveness, drug loading capabilities and reversible thermal gelation. Amphiphilicity guarantees self-assembly and thermoreversibility, while grafting polymers offers the possibility of combining blocks with various properties in one single material. These features make amphiphilic block copolymers excellent candidates for fine tuning drug delivery, gene therapy and for designing injectable hydrogels for tissue engineering. This manuscript revises the main techniques developed in the last decade for the synthesis of amphiphilic block copolymers for biomedical application. Strategies for fine tuning the properties of these novel materials during synthesis are discussed. A deep knowledge of the synthesis techniques and their effect on the performance and the biocompatibility of these polymers is the first step to move them from the lab to the bench. Current results predict a bright future for these materials in paving the way towards a smarter, less invasive, while more effective, medicine.

Influence of Drug Incorporation on the Physico-Chemical Properties of Poly(l-Lactide) Implant Coating Matrices-A Systematic Study

Local drug delivery has become indispensable in biomedical engineering with stents being ideal carrier platforms. While local drug release is superior to systemic administration in many fields, the incorporation of drugs into polymers may influence the physico-chemical properties of said matrix. This is of particular relevance as minimally invasive implantation is frequently accompanied by mechanical stresses on the implant and coating. Thus, drug incorporation into polymers may result in a susceptibility to potentially life-threatening implant failure. We investigated spray-coated poly-l-lactide (PLLA)/drug blends using thermal measurements (DSC) and tensile tests to determine the influence of selected drugs, namely sirolimus, paclitaxel, dexamethasone, and cyclosporine A, on the physico-chemical properties of the polymer. For all drugs and PLLA/drug ratios, an increase in tensile strength was observed. As for sirolimus and dexamethasone, PLLA/drug mixed phase systems were identified by shifted drug melting peaks at 200 °C and 240 °C, respectively, whereas paclitaxel and dexamethasone led to cold crystallization. Cyclosporine A did not affect matrix thermal properties. Altogether, our data provide a contribution towards an understanding of the complex interaction between PLLA and different drugs. Our results hold implications regarding the necessity of target-oriented thermal treatment to ensure the shelf life and performance of stent coatings.

Chitosan-based advanced materials for docetaxel and paclitaxel delivery: Recent advances and future directions in cancer theranostics

Paclitaxel (PTX) and docetaxel (DTX) are key members of taxanes with high anti-tumor activity against various cancer cells. These chemotherapeutic agents suffer from a number of drawbacks and it seems that low solubility in water is the most important one. Although much effort has been made in improving the bioavailability of PTX and DTX, the low bioavailability and minimal accumulation at tumor sites are still the challenges faced in PTX and DTX therapy. As a consequence, bio-based nanoparticles (NPs) have attracted much attention due to unique properties. Among them, chitosan (CS) is of interest due to its great biocompatibility. CS is a positively charged polysaccharide with the capability of interaction with negatively charged biomolecules. Besides, it can be processed into the sheet, micro/nano-particles, scaffold, and is dissolvable in mildly acidic pH similar to the pH of the tumor microenvironment. Keeping in mind the different applications of CS in the preparation of nanocarriers for delivery of PTX and DTX, in the present review, we demonstrate that how CS functionalized-nanocarriers and CS modification can be beneficial in enhancing the bioavailability of PTX and DTX, targeted delivery at tumor site, image-guided delivery and co-delivery with other anti-tumor drugs or genes.

Chitosan coatings to control release and target tissues for therapeutic delivery

The natural biopolymer chitosan has versatile applications in therapeutic delivery. Coating drug delivery matrices or biomaterials with chitosan offers several advantages in drug delivery, including control of drug release, slowing degradation rate and improving biocompatibility. Advanced uses of chitosan in coating form include targeting drug delivery vehicles to specific tissue as well as providing a stimulus-controlled release response. The present review summarizes the current applications of chitosan coatings in the context of different biomaterial delivery technologies, as well as future directions of chitosan coatings for drug delivery technologies under development.

Star-shaped PCL/PLLA blended fiber membrane via electrospinning

Electrospun fiber mesh has been a candidate for guided bone regeneration membrane. However, its poor mechanics property has been limited in clinical application. In this study, various star-shaped poly(ε-caprolactones) (PCLs) are successfully synthesized by ring-opening polymerization and mixed with poly(l-lactide) (PLLA) to be made into blended membranes through electrospinning. Their corresponding properties are evaluated including morphology, thermodynamics, mechanics, and cytotoxicity. The blended fibers show smooth surface and well-distributed structure, which have slight differences in morphology with the change of arm number of star-shaped PCL. Crystallization of the fibrous membrane is influenced by star-shaped PCLs. Glass temperature drops from 64.23 °C for pure PLLA membrane to 53.62-49 °C for the blended membranes. The membranous tensile strength is depended strongly on star-shaped PCLs. The tensile strength goes up with arm number increasing; on the contrary, at the same arm number, the mechanics strength decreases with molecular weight increasing. And the fibrous membrane containing 20 wt.% star-shaped PCL shows better mechanics property compared to the other membranes. The star-shaped PCL/PLLA fiber membrane is not cytotoxicity.

Synthesis and properties of antifouling poly(CL-co-zDMAEMA) zwitterionic copolymer by one-step hybrid copolymerization

A novel biocompatible and biodegradable copolymer was synthesized by one-step hybrid copolymerization of ε-caprolactone (CL) and 2-(N,N-dimethylamino) ethyl methacrylate (DMAEMA) employing (1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phophoranylidenamino]-2Λ5,Λ5-catenadi(phosphazene) (t-BuP4) as a catalyst. The as-synthesized copolymer was betainizated resulting in a zwitterionic copolymer poly(CL-co-zDMAEMA) and the structure of the zwitterionic copolymer was confirmed by the FT-IR, NMR, and XPS measurements. The results of dynamic light scattering (DLS) show that this zwitterionic copolymer can self-assemble into stable micelles. The results of quartz crystal microbalance with dissipation (QCM-D) analysis and MTT measurement suggest that this zwitterionic copolymer possess better protein resistance and lower cell cytotoxicity in vitro in comparison with the cationic copolymer. The pyrene solubilization measurement of copolymers poly(CL-co-zDMAEMA) indicates an excellent pyrene solubilization capacity. These zwitterionic polymer micelles can release drugs in response to specific signals, such as temperature, pH, and enzymes and have a potential application in drug delivery and gene therapy due to their good antifouling, low cytotoxicity and high pyrene solubilization.