Thrombotic and inflammatory complications induced by vascular implants remain a challenge to treat cardiovascular disease due to the lack of self-adaption and functional integrity of implants. Inspired by the dynamic remodeling of the extracellular matrix (ECM), we constructed a bio-mimic ECM with a dual-layer nano-architecture on the implant surface to render the surface adaptive to inflammatory stimuli and remodelable possessing long-term anti-inflammatory and anti-thrombotic capability. The inner layer consists of PCL-PEG-PCL [triblock copolymer of polyethylene glycol and poly(epsilon-caprolactone)]/Au-heparin electrospun fibers encapsulated with indomethacin while the outer layer is composed of polyvinyl alcohol (PVA) and ROS-responsive poly(2-(4-((2,6-dimethoxy-4-methylphenoxy)methyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane) (PBA) fibers. In response to acute inflammation after vascular injury, the outer layer reduces ROS rapidly by PBA degradation for inflammation suppression. The degraded outer layer facilitates inner layer reconstruction with enhanced hemocompatibility through the H-bond between PVA and PCL-PEG-PCL. Furthermore, chronic inflammation is effectively depressed with the sustained release of indomethacin from the inner layer. The substantial enhancement of the functional integrity of implants and reduction of thrombotic and inflammatory complications with the self-adaptive ECM are demonstrated both in vitro and in vivo. Our work paves a new way to develop long-term anti-thrombotic and anti-inflammatory implants with self-adaption and self-regulation properties.

Platelets attribute to the hypercoagulation of blood and maintenance of the tumor vascular integrity, resulting in limited intratumoral perfusion of nanoparticle into solid tumors. To overcome these adversities, we herein present an antiplatelet strategy based on erythrocyte membrane-enveloped proteinic nanoparticles that biomimic nitric oxide synthase (NOS)with co-loading of L-Arginine (LA) and photosensitizer IR783 for local NO release and inhibition of the activation of tumor-associated platelets specifically, thereby enhancing vascular permeability and accumulation of the nanoparticles in tumors. A cRGD-immobolized membrane structure is constructed to actively target platelets and cancer cells respectively, through overexpressed integrin receptors such as integrin alpha(IIb)beta(3) and alpha(v)beta(3), accelerating the inhibition of platelet activation and endocytosis of nanoparticles by tumor cells. Bio-mimicking the arginine/NO pathway in vivo, synergistical delivery of LA and IR783 enables LA molecules readily oxidize to NO with O-2 that is mediated by activated IR783, the resulted NO not only retards the activity of platelets to disrupt the vascular integrity of tumor but also enhances toxicity to cancer cells. In addition, NIR-controlled release localizes the NO spatiotemporally to tumor-associated platelets and prevents undesirable systemic bleeding substantially. The reduction of the hypercoagulable state is further demonstrated by the down-regulation of tissues factor (TF) expression in tumor cells. Our study describes a promising approach to combat cancer, which advances the biomimetic NOS system as the potent therapeutic forces toward clinic applications.

Nitric oxide (NO) has become a highly compelling therapeutic gas for treating vascular diseases due to its versatile functions to vascular responses. Currently, NO biomimetic materials are successfully established through loading catalyst (i.e., Se, Cu) with the vehicle to decompose endogenous NO donors in blood continuously. However, current NO biomimetic materials are susceptible to the non-specific protein fouling, resulting in undesired therapeutic inefficiency with the observation of attenuated or even blocked NO catalytic activities. Herein, we produced a multifunctional nanofilm with dual catalysis based on the vascular stent platform via simply doping one kind of metal (Cu) as cocatalyst into anatase TiO2 crystal. Beneficial synergistic interactions between two kinds of catalysis are reported in this work. The nanofilm surface is endowed with photoinduced super hydrophilic conversion and controlled NO catalytic release simultaneously. The super hydrophilic surface shows the excellent self-cleaning ability to resist protein fouling. Importantly, the maintenance of the protein-resistant surface can effectively improve the NO catalytic release and reduce inflammatory stimuli, contributing to enhanced hemocompatibility. The optimum doping amount of Cu (TiO2 @Cu1, 0.77 wt.%) is determined through the characterization of adjustable photoinduced hydrophilic conversion and appropriate NO catalytic generation within the effective physiological concentration. After vascular implantation in rats, the TiO2 @Cu1 nanofilms achieved elevated performances on antithrombosis, reducing the intima hyperplasia area and promoting rapid reendothelialization at 4 weeks. This study provides a valuable guideline for NO-biomimetic materials used for blood contact devices and paves the way for the surface modification for vascular implants. (c) 2020 Elsevier Ltd. All rights reserved.

Reduction of inflammation and thrombosis caused by implanted devices is critical for clinical success. To this end, the strategy based on programmable release of anti-inflammatory and anti-thrombotic agents from the widely-used polycaprolactone (PCL)/gelatin nanofiber scaffold is developed. The release of 2-O-D-Glucopyranosyl-L-ascorbic Acid (AA-2G) and heparin are controlled by reactive oxygen species (ROS)-responsive poly(ethylene glycol)-based β-thioether ester copolymer (PEGDA-EDT) and mesoporous silica nanoparticles (MSN) in the nanofiber, respectively. The in vitro assay demonstrate that the scaffolds are hemocompatible with the resistance of platelet adhesion; the control release of AA-2G prevents initial inflammation and oxidation of the blood cells, and the subsequent release of heparin entitles nanofibers with long-term anti-thrombotic capability. In addition, rapid endothelialization is obtained on the surface of nanofiber scaffolds for the further enhancement of the hemocompatibility. In vivo implant evaluation convinces that the nanofiber scaffolds possess high biocompatibility with the substantial resistance for inflammation and thrombosis. Hence, our work paves a new way to develop the anti-inflammatory and anti-thrombotic tissue-engineering substrates through programmable delivery of two or multiple drugs. © 2020 Elsevier Ltd

The availability of biocompatible, anti-bacterial coatings is of extreme importance for the development of biomedical devices. However, it has proven to be difficult to achieve both biocompatibility and bactericidal properties simultaneously. In the present work, as a novel, alternative approach, a quaternary ammonium salt -based poly(N-isopropylacrylamide) (QAS-PNIPAM) microgel was used both as the bactericidal agent and as an anchor system for the attachment of a cyto-compatibility-enhancing component. QAS-PNIPAM microgels were first prepared as thin films on silicon wafer. The QAS component of the film, as well as having strong inherent bactericidal properties, also provided binding sites for attachment of a glycopolymer containing sulfonate groups via attractive electrostatic interactions. It was shown that introduction of the sugar units improved the cyto-compatibility of the microgel film without compromising its bactericidal efficacy. It is proposed that such mi-crogel coatings may serve more generally as intermediates for the attachment of biofunctional components to biomaterial surfaces.

Cell behaviors are regulated by a dynamic and complex environment characterized by biophysical, mechanical and biochemical properties. However, most works regulate cell behaviors under static conditions or by external factors. To control cell adhesion and proliferation with a dynamic and mechanical environment, we pattern the surface on self-healing copolymer P(MMA/nBA). The copolymer P(MMA/nBA) with the composition of 48/52 (MMA/nBA) recovers nearly 100% of its original tensile strains after 86 h of recovery from deformation. The physical patterns on P(MMA/nBA) film are obtained over large areas and the size of the hole and the width of connecting bar are in line with the copper grid specifications. The patterned surface tends to be flat after 12 h with almost 75%-80% recovery. Compared with cell incubation on polystyrene flat and patterned surface of P(MMA/nBA) film without self-healing capability, the number and morphology of cells are well manipulated on the patterned surface of self-healing P(MMA/nBA) film. This approach provides a convenient method for dynamically regulating the cell behaviors on the surface of self-healing materials without chemical or biological modifications.

Polymer nanoparticulate drug delivery systems that respond to reactive oxygen species (ROS) and glutathione (GSH) simultaneously at biologically relevant levels hold great promise to improve the therapeutic efficacy to cancer cells with reduced side effects of chemo drugs. Herein, a novel redox dual-responsive amphiphilic block copolymer (ABP) that consists of a hydrophilic poly (ethylene oxide) block and a hydrophobic block bearing disulfide linked phenylboronic ester group as pendant is synthesized, and the DOX loaded nanoparticles (BSN-DOX) based on ABPs with varied hydrophobic block length are fabricated for DOX delivery. The self-immolative leaving reaction of phenylboronic ester triggered by extracellular ROS and the cleavage of disulfide linkages induced by intracellular GSH both lead to rapid DOX release from BSN-DOX, resulting in an on-demand DOX release. Moreover, BSN-DOX show better tumor inhibition and lower side effects in vivo compared with free drug.

Polystyrene-block-polyisoprene-block-polystyrene (SIS) has been used as biomaterials due to its soft and stable properties under physiological conditions. However, the thrombotic and inflammatory complications caused by SIS restrain its application as blood-contacting implant. To overcome this problem, the hydrophilic core-shell structured SIS-based microfiber with antioxidant encapsulation is fabricated with one-step reactive electrospinning. We demonstrate that the phase separation of SIS and acylated Pluronic F127 (F127-DA) components and crosslinking during electrospinning renders the microfiber blood compatible and stable under physiological condition; the encapsulation of 2-O-d-glucopyranosyl-l-ascorbic acid (AA-2G) in microfiber and subsequent release of AA-2G detoxifies the excess reactive oxygen species (ROS). The microfibers are nontoxic to cells and promote the fast growth and proliferation of human umbilical vein endothelial cells (HUVECs) in the presence of ROS; the thrombotic and inflammatory complications are effectively reduced with implant evaluation in vivo. Therefore, our work paves a new way to improve the biocompatibility of SIS, making it a promising candidate for blood contact materials.

Implantation of a drug-eluting stent is the most common treatment method for patients with cardiovascular atherosclerosis. However, this treatment may delay re-endothelialization, and the drug polymer-coated stent may induce thrombosis months after a stent implantation. The development of polymer-free drug-eluting stents is a promising approach to overcome these shortcomings. Titanium dioxide nanotubes (TiO2-NTs) are excellent drug carriers and have been considered as a potential material for polymer-free drug-eluting stents. However, TiO2-NTs reportedly induce severe blood clotting, which is a significant shortcoming for use as a stent. Vascular stents must be compatible with blood and must have antibacterial, anti-inflammatory, and selective inhibitory activities in the abnormal hyperplasia of smooth muscle cells, instead of delaying the re-endothelialization of endothelial cells. To meet these requirements, we presented a composite material that featured ultraviolet (UV) irradiation of TiO2-NTs-containing silver nanoparticles (AgNPs). The AgNPs were loaded in the lumen of TiO2-NTs as a representative compound to suppress the inflammatory response and hyperplasia. UV irradiation was performed as a novel method to improve the anticoagulant ability of the AgNP-loaded TiO2-NTs. The chemical state and biocompatibility of the UV-TiO2-NTs@AgNPs were evaluated. UV irradiation strongly improved the anticoagulant ability of the TiO2-NTs and moderated the release of Ag+ from AgNPs, which selectively suppressed the inflammatory response and hyperplasia. Furthermore, the UV-TiO2-NTs@AgNPs-2 displayed enhanced biocompatibility evidenced by the inhibition of platelet adhesion, bactericidal activity, selective suppression of the smooth muscle cell proliferation, and inhibition of the adhesion of macrophages. The collective findings indicate the potential of the photofunctionalized TiO2-NTs loaded with AgNPs as a material for polymer-free drug-eluting stents.

The controllable release is necessary for ideal drug delivery technologies. Because of their high specific surface area and high porosity, titanium dioxide nanotubes (TNTs) have been widely used as drug carriers in medical devices. By loading copper as the catalyst, nitric oxide (NO) generation was facilitated by catalyzing the decomposition of renewable endogenous NO donors in vivo. Herein, the long-term controllable release profile of NO is highlighted owing to the multilayer polydopamine (PDA) cap structure. Different layers of PDA are used to adjust the NO release behavior, and the results show that three layers of PDA can not only effectively prevent the burst release of NO but also maintain long-term stable release of copper ion and NO. The bioactivity of the NO generated from three-layer PDA-modified copper-loaded TNTs (PDA-3L-NTCu2) and unmodified copper-loaded TNTs (NTCu2) are verified by our work, indicating effective inhibition of platelet activation, thrombosis, inflammation, and intimal hyperplasia. Importantly, the PDA-3L-NTCu2 show selectively promote the growth of endothelial cells in vitro and outstanding re-endothelialization for 4 weeks in vivo, as compared to NTCu2, TNTs, and 316L stain steel. This study suggests that copper-loaded with PDA modification helps us achieve controlled long-term stable local NO release with well-retained bioactivity and enhanced re-endothelialization. Copyright © 2020 American Chemical Society.