Editorial: Advances in surface engineering: integrated innovations across materials and applications

The field of surface engineering continues to evolve at a remarkable speed, driven by advances in nanostructured materials, hybrid interfaces, and multifunctional coatings. This issue brings together a diverse selection of six research articles that (although distinct in scope) share a unifying thread: the strategic use of surface modification and nanoscale design to overcome longstanding challenges in optical, biomedical, environmental, and sensing applications. Each contribution demonstrates how innovations at the interface level can dramatically enhance performance, stability, and functionality.One of the key contributions in this issue examines poly(4-chloroaniline)/g-C3N4 nanocomposites, where Abdeltwab and colleagues1 fabricate hybrid films that exhibit significant improvements in optical dispersion, dielectric behavior, and nonlinear optical response. Through multiple physicochemical analyses, the authors demonstrate that embedding graphitic carbon nitride nanosheets within the polymer matrix increases the refractive index, enhances optical conductivity, and modifies band-edge energies. These findings underscore the growing potential of polymer–inorganic architectures as flexible, tunable platforms for next-generation optoelectronic devices.The role of nanoscale design in biomedical materials is further highlighted by Aktas et al.2, who investigate Cu/SiO2 thin films deposited on TiO2 nanotubes formed on Ti15Mo alloys. By carefully tuning copper content within co-deposited films, the authors identify a 50:50 Cu:SiO2 ratio that delivers exceptional antibacterial activity, achieving 80.7% inhibition of E. coli while preserving the nanotube morphology and hydrophilic surface characteristics essential for biocompatibility. This work illustrates how composite nanofilms can address infection risks associated with metallic implants without compromising surface functionality or cytocompatibility.Biodegradable magnesium alloys represent another critical frontier for biomedical engineering, and Ensaniat et al.3 address this challenge through the combined use of laser surface texturing (LST) and micro-arc oxidation (MAO). Their study reveals that LST/MAO hybridization produces strongly adherent, uniformly porous oxide layers with superior corrosion resistance relative to laser-only or uncoated Mg–Ca alloys. Notably, the LST/MAO coating yields the lowest corrosion current density, the highest charge-transfer resistance, and the most stable long-term performance in simulated body fluid. The enhanced hydroxyapatite formation further suggests that this dual-treatment strategy can considerably improve both durability and bioactivity in magnesium-based implants.Surface modification also plays a transformative role in polymer technologies, as shown by Wang et al.4 in their development of halloysite nanotube composites modified with WO3 and polydopamine (PDA). When embedded in PVC matrices, these hierarchical HNTs@WO3/PDA fillers dramatically enhance UV-shielding capability, blocking 55.1% UVA and 62.8% UVB radiation at only 2 wt% loading. The films also exhibit improved thermal stability, indicating an environmentally conscious, scalable approach to producing protective coatings, packaging materials, and weather-resistant surfaces.Optical device performance is the focus of another contribution, in which Yeoh et al.5 apply PTFE hydrophobic coatings via RF magnetron sputtering to ABS and SAN substrates commonly used in endoscopic lenses. Remarkably, a 60-min sputtering process yields coatings with exceptionally high light transmittance (∼98%) and significantly improved water repellence, metrics that exceed those of dip-coated, spin-coated, and some commercial oxide-coated comparators. This work demonstrates that RF sputtering is a powerful strategy for producing durable anti-fogging, anti-adhesion coatings for medical optical instruments, where clinical visibility is paramount.The issue concludes with the work of Liu et al.6, who tackle the longstanding challenge of detecting hydrophobic polycyclic aromatic hydrocarbons using surface-enhanced Raman scattering (SERS). By functionalizing gold nanoparticles with sulfhydryl-modified cyclodextrin, they create an SD@AuNPs substrate that captures 3,4-benzopyrene via host–guest inclusion. Finite-element electromagnetic simulations and DFT analysis reveal a synergistic electromagnetic–chemical enhancement mechanism, yielding a theoretical enhancement factor of 4.87 × 109 and an experimental value of 1.99 × 108. This approach not only enables sensitive detection of a molecule that typically exhibits weak adsorption on noble metals but also establishes a general framework for SERS detection of hydrophobic pollutants in complex environments.Together, these six contributions showcase how surface innovation can address challenges across multiple sectors: enhancing optical functionality, improving implant safety, strengthening corrosion resistance, providing environmental protection, enabling real-time diagnostics, and enhancing the performance of biomedical devices. Each article offers insights into how careful control of chemistry, morphology, and nanoscale interactions can unlock new capabilities in materials that are already widely used or highly sought after.As always, we extend our gratitude to the authors for their high-quality submissions, to the reviewers for their rigorous evaluations, and to the readership whose engagement drives continued advances in the field. The research presented in this issue reflects the depth and breadth of progress underway within the surface engineering community. We hope these studies will inspire further interdisciplinary collaboration and encourage new avenues of exploration in nanoscale materials design, fabrication, and application.We look forward to sharing future advancements with you in the coming issues and remain committed to showcasing impactful developments that continue to shape the future of surface innovation.