Nanosized TiCN/TiN films were deposited on AZ31 by reactive magnetron sputtering under different acetylene flows. The microstructures of obtained films were characterized, and their corrosion behaviors were also investigated. The films doped with carbon atoms under different acetylene flows own different structures and grain sizes. The grain size decreased to some extent, and the film structure changed from polycrystalline to nanocrystalline, with an increase of C₂H₂ flow. The surface morphology also changed from rough to smooth, with an increase of C₂H₂ flow. The Tafel curves and electrochemical impedance spectroscopy (EIS) demonstrated that the composite films could greatly improve the corrosion resistance of bare substrates in a 3.5% NaCl solution, and the films’ corrosion resistance is different, owing to their different structures and grain sizes.

A duplex coating system, consisting of a laser-cladded Fe-Cr-based interlayer and a silicon-doped diamond-like carbon (Si-DLC) top layer, was deposited on medium carbon steel substrate using laser cladding (LC) followed by plasma-enhanced chemical vapor deposition (PECVD). The LC interlayer (thickness of 1.5 mm, hardness of 455–620 HV0.3) was applied on both argon ion-etched and non-etched substrate surfaces. The microstructure and adhesion strength of the coatings were systematically investigated. The results show that the LC interlayer significantly enhanced the mechanical support for the Si-DLC coating, increasing adhesion strength by 4~5 times compared to direct deposition. Argon ion etching introduced micro-roughened surface features, increasing interfacial contact area and further boosting adhesion. A synergistic effect was observed between substrate hardness and ion etching in enhancing Si-DLC coating adhesion.

To mitigate the high residual stress inherent in single-layer diamond-like carbon (DLC) films, we fabricate alternating soft/hard multilayer DLC thick films using a cage-type hollow cathode plasma-enhanced chemical vapor deposition (PECVD) system. The microstructure, mechanical properties, and corrosion resistance of these films were systematically investigated. Periodic film structures were characterized via scanning electron microscopy (SEM), Raman spectroscopy, atomic force microscopy (AFM), and X-Ray photoelectron spectroscopy (XPS). Adhesion and hardness were evaluated using a scratch tester and a nanoindentation tester, respectively, while corrosion resistance was assessed by dynamic potential polarization tests in a 3.5 wt% NaCl solution. Findings indicate that as the modulation period of the Si-DLC films increases, a greater proportion of high-energy carbon particles penetrate the non-biased layer under workpiece bias, ultimately disrupting the layered structure in the 90-layer film. This results in densification, reflected in three key improvements: (1) an increase in sp³-bonded carbon content and enhanced smoothness, (2) enhanced adhesion (from 34 N to 46 N) and nanohardness (from 4.94 GPa to 8.41 GPa), and (3) a tenfold reduction in corrosion current density (i_corr) compared to single-layer Si-DLC films.

The photothermal conversion capability of polydopamine (PDA) was exploited to load the anticancer drug doxorubicin (DOX) onto its surface via π-π stacking and hydrogen-bond interactions, yielding a PDA-DOX complex. In this study, biocompatible poly-L-lactic acid (PLLA) was employed as a shell material to fabricate multifunctional PLLA composite PDA-DOX (PLLA@PDA-DOX) nanobubbles with integrated functions of ultrasound imaging, photothermal therapy, and chemotherapy. The fabricated nanobubbles exhibited a uniform mean diameter of 489.30 ± 6.96 nm with a Polydispersity index (PDI) of 0.226 ± 0.01 and a DOX loading efficiency of 3.27%. Acute toxicity evaluation in mice revealed that the maximum tolerated dose of PLLA@PDA-DOX nanobubbles was markedly higher than the clinical equivalent dose, showing no detectable toxicity or allergic reactions. Under near-infrared (NIR) laser irradiation, the inhibition rate of HCCLM3 cells increased from 50.1% to 64.45%, indicating enhanced therapeutic efficacy through the combined effects of photothermal therapy and chemotherapy. Moreover, compared with the free DOX group, the survival rate of LX-2 cells in the composite nanobubble group significantly increased from 18.9 ± 1.56% to 68.8 ± 3.08%, suggesting that the PLLA@PDA-DOX nanobubbles effectively reduced the direct cytotoxicity of DOX by preventing its immediate contact with cells. Collectively, the results confirm that PLLA@PDA-DOX nanobubbles possess excellent biocompatibility, robust ultrasound imaging performance, and enhanced antitumor efficacy under NIR irradiation. This multifunctional nanosystem demonstrates promising potential as an integrated platform for simultaneous cancer diagnosis and therapy.