Biomaterials play an increasing role in modern health care systems. Biocompatibility poses a significant challenge for manufacturers of medical devices and contemporary intelligent drug delivery technologies from materials development to market approval. Despite a highly regulated environment, biocompatibility evaluation of biomaterials for medical devices is a complex task related to various factors that include mainly chemical nature and physical properties of the material, the contact tissue and duration of contact. Although international standards, such as ISO 10993-1, are generally employed to prove regulatory compliance needed for market clearance or for initiating clinical investigations, they may not offer sufficient guidance, or risk-management perspective when it comes to choosing materials or appropriate in vitro biocompatibility screening methods when developing medical devices. The global normative approach towards the biocompatibility evaluation of medical devices is presented in this review, with a focus on in vitro studies. Indeed, a risk-management approach towards the judicial choice of in vitro tests throughout the development and production of medical devices and drug delivery systems will facilitate rapid regulatory approval, avoid unnecessary animal studies, and ultimately reduce risks for patients. A detailed overview towards the construction of a comprehensive biological evaluation plan is described herein, with a focus on polymer-based materials used in medical applications. Polymeric materials offer a broad spectrum of applications in the manufacturing of medical devices. They are extensively employed within both conventional and innovative drug delivery systems with superior attributes supporting robust, extended use capacity, capable of meeting specific requirement such as adhesion, drug release, and more. Various methods of biocompatibility assessment are detailed within, with an emphasis on scientific analysis. This review may be of interest to those involved in the design, manufacturing and in vitro testing of medical devices and innovative drug delivery technologies, specifically with respect to a risk-management approach towards the biocompatibility assessment of polymer-based devices.
In the context of cancer treatment, gold nanoparticles (AuNPs) are considered as very promising radiosensitizers. Here, well-defined polymer-grafted AuNPs were synthesized and studied under gamma irradiation to better understand the involved radiosensitizing mechanisms. First, various water-soluble and well-defined thiol-functionalized homopolymers and copolymers were obtained through Atom Transfer Radical Polymerization. They were then used as ligands in the one-step synthesis of AuNPs, resulting in stable hybrid metalpolymer nanoparticles. Second, these nano-objects were irradiated in solution by gamma rays at different doses. Structures were fully characterized through SEC, SAXS and SANS measurements, prior and after irradiation. We were thus able to quantify and to localize radiation impacts onto the grafted polymers, revealing the production sites of reactive species around AuNPs. Both external and near-surface scissions were observed. Interestingly, the ratio between these two effects was found to vary according to the nature of polymer ligands. Medium-range and long-distance dose enhancements could not be identified from the calculated scission yields, but several mechanisms were considered to explain high yields found for near-surface scissions. Then, cytotoxicity was shown to be equivalent for both nonirradiated and irradiated polymer-grafted NPs, suggesting that released polymer fragments were non-toxic. Finally, the potential to add bioactive molecules such as anticancer drugs has been explored by grafting doxorubicin (DOX) onto the polymer corona. This may lead to nano-objects combining both radiosensitization and chemotherapy effects. This work is the first one to study in details the impact of radiation on radiosensitizing nano-objects combining physical, chemical and biological analyses.
The purpose of this study is to present
the poly(caprolactone) (PCL) functionalization by the covalent grafting
of poly(sodium styrene sulfonate) on electrospun scaffolds using the
“grafting from” technique and evaluate the effect of
the coating and surface wettability on the biological response. The
“grafting from” technique required energy (thermal or
UV) to induce the decomposition of the PCL (hydro)peroxides and generate
radicals able to initiate the polymerization of NaSS. In addition,
UV irradiation was used to initiate the radical polymerization of
NaSS directly from the surface (UV direct “grafting from”).
The interest of these two techniques is their easiness, the reduction
of the number of process steps, and its applicability to the industry.
The selected parameters allow controlling the grafting rate (i.e.,
degree of functionalization). The aim of the study was to compare
two covalent grafting in terms of surface functionalization and hydrophilicity
and their effect on the in vitro biological responses of fibroblasts.
The achieved results showed the influence of the sulfonate functional
groups on the cell response. In addition, outcomes highlighted that
the UV direct “grafting from” method allows to moderate
the amount of sulfonate groups and the surface hydrophilicity presents
a considerable interest for covalently immobilizing bioactive polymers
onto electrospun scaffolds designed for tissue engineering applications
using efficient post-electrospinning chemical modification.
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