Although microplastics have been detected in human blood, placenta and other tissues. In this study, for the first time, we characterized the presence and variation of microplastic deposition patterns in three human skeletal tissues, namely the bone, cartilage, and intervertebral discs. Forty microplastic fragments were observed in 24 samples from the bone, cartilage, and intervertebral disc, ranging from 25.44 to 407.39 μm in diameter. The deposition abundance of microplastics in the human intervertebral disc (61.1 ± 44.2 particles/g) was higher than those in the bone (22.9 ± 15.7 particles/g) and cartilage tissue (26.4 ± 17.6 particles/g). The average sizes of microplastics in intervertebral discs (159.5 ± 103.8 μm) and bone (138.86 ± 105.67 μm) were larger than that in the cartilage tissue (87.5 ± 30.7 μm). The most frequently identified polymers were polypropylene (35 %), ethylene vinyl acetate copolymer (30 %), and polystyrene (20 %). The in vivo experiment suggested that microplastics invaded the bone, cartilage, and intervertebral discs through blood circulation after 4 weeks of exposure. Serum levels of tumor necrosis factor-α (TNF-α), Type Ⅰ procollagen amino-terminal peptide (PINP), and tartrate-resistant acid phosphatase-5b (TRACP-5b) were elevated compared with those in the control group (p < 0.05). Our study suggests that microplastics invade the bone, cartilage, and intervertebral discs through the blood supply, causing distinct patterns of microplastic accumulation in these regions. Microplastic invasion can affect skeletal health by influencing the expression of inflammatory and bone morphogenetic cytokines. These findings provide insights into investigating the impact of microplastics on human skeletal health.

The effective measure to promoting endothelial repair is to construct a surface similar to that of normal vascular on blood contact materials. The construction of cell culture platform regulating platelets, endothelial cells (ECs) and Smooth muscle cells (SMCs) may provide more help to promote endothelial repair. In this work, a novel versatile cell research platform UV-P-PDA@TiO2 was constructed by magnetron sputtering and photoetching. The surface of UV-P-PDA@TiO2 was evaluated by materials science methods such as FTIR, Raman, Micro BCA and WCA, and cell culture was performed on the surface. These results indicated that UV-P-PDA@TiO2 platform regulated the cellular behavior of platelets, ECs, and SMCs, achieved selective adhesion, and exhibited orientation. The advantage of histocompatibility was demonstrated by in vivo tests that UV-P-PDA@TiO2 had pattern stability and inhibited tissue proliferation. Conceivably, the regulating the multicellular UV-P-PDA @ TiO2 culture platform may provide a versatile surface engineering strategy for biomaterials.

Microplastics are synthetic solid particles or polymeric matrix composites smaller than five millimeters, potentially being absorbed by various organs and resulting in adverse health effects. Nevertheless, the presence of microplastics in the human skeletal system remains uncertain. In this study, Raman Microspectroscopy was used to detect microplastics within three parts of human skeletal system: bone, cartilage and intervertebral disc. A total of 40 microplastic fragments were observed in twenty-four tissue samples from the skeletal system, making the first such observation. The quantities of microplastics present in intervertebral discs (61.1±44.2 particles/g, average size 159.5±103.8 μm), bone (22.9±15.7 particles/g, average size 138.86±105.67 μm) and cartilage (26.4±17.6 particles/g average size 87.5±30.7 μm) exhibited slight variations. The most frequently identified polymers were polypropylene (PP, 35%), ethylene vinyl acetate copolymer (EVA, 30%) and polystyrene (PS, 20%). These polymers find extensive applications in disposable items, tableware, packaging, clothes, and various other products integral to daily life, such as bottled water consumption and take-out food services. This study has established the prevalence occurrence of microplastics in the human skeletal system for the first time. These findings lay the groundwork for future investigations into the impact of microplastics on human health.

Dopamine is a small molecule inspired by the dopamine motif of mussel foot proteins, and PDA is formed by the self-polymerization of dopamine. Under the UV-irradiation，PDA would be oxidized by reactive oxygen species (ROS) which were produced by photocatalytic reactions on TiO2 surfaces，thus regulating the adhesion behavior of endothelial cells (ECs) TiO2 inhibited platelet (Plt) adhesion after UV exposure. Polydopamine (PDA)-TiO2 micropatterns (P-PDA-TiO2) were prepared by magnetron sputtering and photolithography. This micropatterns successfully achieves selective adhesion of Plt and ECs. The selective adhesion of ECs disappears after vacuum reduction. In contrast to conventional cell patterning strategies, P-PDA-TiO2 can easily achieve pattern separation of ECs and Plts and provide a new concept for building complex blood-contacting devices.

Dopamine has been widely used for surface modification of cardiovascular medical devices as it forms films on most substrates that provide functional groups for surface chemical modification. However, under oxidative stress, the phenolic hydroxyl group on dopamine can undergo reversible transformation into phenol-semiquinone-quinone, which can cause cytotoxicity and immunotoxicity. In this study, we measured the effects of semiquinone on the behavior of vascular wall cells and inflammatory cells under oxidative stress via ultraviolet irradiation with a hydrogen peroxide diluent. Na 2 S 2 O 3 was used as a stabilizer to obtain a semiquinone-rich poly-dopamine film, then phenol-semiquinone-quinone ratio on its surface was evaluated at three irradiation-oxidation time points. We found that the poly-dopamine film with ultraviolet irradiation in hydrogen peroxide solution for 15 min had the highest semiquinone occupancy of 19.18%. In the experimental group irradiated for 15 min, endothelial cells were cultured statically for 3 days and the number of surface adherent endothelial cells in the group with added semiquinone stabilizer was reduced to 73% of that in the group without stabilizer, indicating that semiquinone rich surface inhibits adhesion and proliferation of endothelial cells; Smooth muscle cells were cultured statically for 3 days, and the number of adherent smooth muscle on surfaces without stabilizer was reduced to 75% of that on surfaces with stabilizer added, indicating that semiquinone rich surfaces promote smooth muscle proliferation. These results demonstrate that semiquinone can adversely affect the repair effect after implantation of cardiovascular materials. Therefore, our study provides a reference for the application and optimization of dopamine in cardiovascular implant materials.

Silver nanoparticles (AgNPs) are widely used because of their excellent antimicrobial properties. However, the poor hemocompatibility limits the application of AgNPs in blood contact materials. General approaches to improve the hemocompatibility of AgNPs-containing surfaces are to construct barrier layers or co-immobilize anticoagulant biomolecules. But such modification strategies are often cumbersome to prepare and have limited applications. Therefore, this study proposes a simple UV-photo-functionalization strategy to improve the hemocompatibility of AgNPs. We loaded AgNPs onto titanium dioxide (TiO2) nanoparticles to form a composite nanoparticles (Ag@TiO2NPs). Then, UV treatment was performed to the Ag@TiO2NPs, utilizing the diffusible photo-induced anticoagulant properties of TiO2 nanoparticles to enhance the hemocompatibility of AgNPs. After being deposited onto the PU surface, the photo-functionalized Ag@TiO2NPs coating showed excellent antibacterial properties against both Gram-positive/Gram-negative bacteria. Besides, In vitro and ex-vivo experiments demonstrated that the photo-functionalized Ag@TiO2NPs coating had desirable hemocompatibility. This modification strategy can provide a new solution idea to improve the hemocompatibility of metal nanoparticles.