Porous vaterite containers of 400 nm size are studied with respect to intracellular drug delivery applications. A generic crystal phase transition from vaterite to calcite serves as a novel payload release mechanism, which reveals a delayed burst-release. This will permit control of the pharmacokinetics allowing for applications like preventive drug administration or scheduled application of pharmaceuticals during long term therapy. Experiments with two types of payloads, providing different molecular weights and zeta-potentials, demonstrate a flexible way of tailoring the payload delivery time via the molecular properties of the cargo. A dual in vitro cellular uptake experiment with human ovarian carcinoma cells ES2 and human fibroblasts MRC5 shows no cytotoxicity, no influence on cell viability, and fast penetration of substance-loaded containers into cells. Flow cytometry analysis proves high uptake rates and 3D microscopy analysis reveals the intracellular distribution.

Polyetheretherketone (PEEK) is a thermoplastic material with outstanding properties and high potential for biomedical applications, including hermetic encapsulation of active implantable devices. Different biomedical grade PEEK films with initial degree of crystallinity ranging from 8% to 32% (with or without mineral filling) were inspected. PEEK surfaces were treated with nitrogen RF plasma and the effects on materials crystallinity and self‐bonding were evaluated. In particular, the relationship between auto‐adhesive properties and crystalline content of PEEK before and after plasma treatment was examined.PEEK samples showed different bonding strength depending on their degree of crystallinity, with higher self‐bonding performance of mineral‐filled semi‐crystalline films. XRD did not show any modification of the PEEK microstructure as a result of plasma treatment, excluding a significant influence of crystallinity on the self‐bonding mechanisms. Nevertheless, plasma surface treatment successfully improved the self‐bonding strength of all the PEEK films tested, with larger increase in the case of semi‐crystalline unfilled materials. This could be interpreted to the increase in chain mobility that led to interfacial interpenetration of the amorphous phase.

Polyurethane surfaces were modified by covalent immobilization of different molecular weight heparins (fractionated Mw ~3000 Da, and unfractionated Mw ~17,000—19,000 Da) and examined by ESCA, AFM, and contact angle goniometer. The effect of these different surface-immobilized heparins on blood protein adsorption and on platelet adhesion, were examined after incubating the samples with platelet-poor and platelet-rich plasma. Protein adsorption kinetics was studied by electrophoresis and the platelets adhered on the surfaces were examined by SEM after incubation. The two heparin types clearly showed different behavior with respect to protein adsorption, especially in the early stages of blood plasma interaction. After a 5-min incubation in plasma, low molecular weight heparin-immobilized polyurethanes (PU-LMWH) showed three times less protein adsorption compared to unfractionated heparin-immobilized polyurethanes (PU-UFH). The total amount of adhered protein became more similar as the incubation time was extended. The morphology of adhered platelets on material surfaces demonstrated differences: PU-UFH had clusters with some pseudopodia extensions, while PU-LMWH surfaces had round-shaped platelets with little clustering. For contact times >15 min, the amount of adsorbed proteins and adhered platelets on the heparinized PU surfaces decreased.

Carbon nanostructures (CNs), such as carbon nanotubes, fullerenes, carbon dots, nanodiamonds as well as graphene and its derivatives present a tremendous potential for various biomedical applications, ranging from sensing to drug delivery and gene therapy, biomedical imaging and tissue engineering. Since most of these applications encompass blood contact or intravenous injection, hemocompatibility is a critical aspect that must be carefully considered to take advantage of CN exceptional characteristics while allowing their safe use. This review discusses the hemocompatibility of different classes of CNs with the purpose of providing biomaterial scientists with a comprehensive vision of the interactions between CNs and blood components. The various complex mechanisms involved in blood compatibility, including coagulation, hemolysis, as well as the activation of complement, platelets, and leukocytes will be considered. Special attention will be paid to the role of CN size, structure, and surface properties in the formation of the protein corona and in the processes that drive blood response. The aim of this review is to emphasize the importance of hemocompatibility for CNs intended for biomedical applications and to provide some valuable insights for the development of new generation particles with improved performance and safety in the physiological environment.