The review, authored by Ricardo Luiz Perez Teixeira of the Federal University of Itajubá in Brazil and published on 24 August 2026, takes an unusually rigorous approach for a materials-science synthesis. Following the PRISMA 2020 reporting framework, the author searched the CAPES Journal Portal — which provides access to Web of Science, Scopus, ScienceDirect, and other major databases — for peer-reviewed studies published between January 2000 and June 2026, with particular emphasis on the most recent four years. The screening funnel was steep: 70 records identified, 52 screened by title and abstract, 23 assessed in full text, and just 11 studies surviving every eligibility criterion. The author deliberately chose a qualitative critical synthesis over a statistical meta-analysis, because the included studies varied so widely in treatment parameters, electrochemical protocols, and biological assays that pooling their numbers would have been misleading.

Why does surface integrity matter so much for a metal that has been implanted successfully since the mid-twentieth century? The answer lies in where degradation begins. Once an implant enters the body, its surface becomes the primary interface with proteins, cells, bacteria, and mechanical forces. Corrosion in physiological fluid is an electrochemical process: chloride ions attack the passive film, nucleating pits that act as stress concentrators and crack-initiation sites. Wear from cyclic loading strips the film away, exposing fresh metal that dissolves faster than protected surfaces. The two processes feed each other in a phenomenon called tribocorrosion, in which total material loss exceeds the sum of wear alone and corrosion alone — a synergistic excess that the review frames using the standard ASTM G119 decomposition into mechanical wear, electrochemical corrosion, and their interaction term. For load-bearing implants such as modular orthopedic junctions, this synergy is arguably the single most important limit on service life.

The review’s central technical argument concerns mechanical surface treatments: processes such as shot peening, severe shot peening, burnishing, deep rolling, ultrasonic surface modification, and laser shock peening that deform the near-surface region without changing the alloy’s bulk chemistry. Each treatment leaves a different microstructural signature. Shot peening bombards the surface with spherical media, generating compressive residual stresses and work hardening that delay fatigue-crack initiation. Severe shot peening pushes deformation further, producing ultrafine-grained or even nanocrystalline surface layers with dramatically increased dislocation density. Burnishing and deep rolling smooth the surface while pressing compressive stresses deeper into the subsurface. Ultrasonic nanocrystal surface modification uses high-frequency impacts to build nanostructured layers. Laser shock peening, the most exotic of the family, drives plasma shock waves from pulsed laser irradiation into the metal, achieving deep compressive stress fields with minimal surface roughening — an advantage the review highlights for preserving passive-film stability.

But here is where the review delivers its most provocative finding: none of these microstructural improvements reliably predicts corrosion resistance on its own. Grain refinement, for instance, has been reported both to accelerate passive-film formation — because denser grain boundaries provide more diffusion pathways for chromium migration — and to increase susceptibility to localized corrosion, because the same boundaries create electrochemical heterogeneity that chloride ions can exploit. Strain-induced martensitic transformation, a hallmark of deformed metastable austenitic steels like 316L, improves hardness and wear resistance but can introduce galvanic coupling between martensitic and austenitic regions, with consequences for pitting that vary with martensite fraction, morphology, and distribution. Compressive residual stresses, the workhorse of fatigue improvement, show similarly contradictory electrochemical effects. The review’s conclusion is blunt: no single surface-integrity parameter — roughness, residual stress, grain size, or phase fraction — can predict how an implant will behave in the body.

This matters clinically because the biological consequences of surface modification are equally entangled with the electrochemical ones. Protein adsorption, the first event after implantation, is governed by surface energy, roughness, and chemistry, and it sets the stage for everything that follows: osteoblast attachment, macrophage polarization, fibroblast migration, angiogenesis, and bacterial colonization. Nanostructured surfaces produced by severe plastic deformation have shown promise in promoting osteogenic differentiation and even steering macrophages toward pro-regenerative phenotypes — an emerging field the review identifies as osteoimmunomodulation. Yet the same roughness that helps bone integrate can increase bacterial adhesion, and corrosion-induced release of iron, chromium, nickel, and molybdenum ions can trigger chronic inflammatory signaling and osteolysis in susceptible patients. The review emphasizes that these biological processes cannot be evaluated independently of the tribocorrosion and corrosion behavior that feed them ions and debris.

The methodological critique running through the review is as important as its scientific synthesis. Because tribocorrosion outcomes depend sensitively on contact geometry, counterbody material, electrolyte composition, loading regime, and repassivation kinetics, studies using different protocols frequently reach opposite conclusions about the same treatment. The author calls for internationally standardized testing protocols that reproduce clinically relevant mechanical and electrochemical conditions, alongside implant retrieval analyses and long-term in vivo validation — the missing links between laboratory promise and clinical reality. Without such standardization, the field risks optimizing surface treatments against laboratory benchmarks that do not translate to decades of service inside a living patient.

Looking forward, the review identifies several converging frontiers. Mechanical surface treatments are increasingly viewed not as standalone solutions but as substrate-preparation steps for multifunctional surfaces: calcium phosphate and hydroxyapatite coatings that mimic bone mineral, oxide layers that double as platforms for bioactive molecules, antibacterial nanotopographies that reduce colonization without compromising host-cell compatibility, and gradient architectures that combine hardness with toughness. The author also highlights the growing role of computational tools — machine-learning-guided materials design, digital twins for implant performance prediction, and artificial-intelligence-assisted optimization of processing parameters — as approaches that could finally tame the parameter space that has made mechanical surface treatment results so difficult to compare across laboratories.

For a material often dismissed as old-fashioned next to titanium and cobalt-chromium alloys, AISI 316L retains a stubborn advantage: it is cheap, manufacturable, clinically familiar, and — crucially — highly responsive to surface engineering. The review’s ultimate message is that the next generation of stainless-steel implants will not be defined by new alloy chemistries but by a more sophisticated understanding of how deformation, microstructure, electrochemistry, and biology interact at the surface. Getting that picture right, the author argues, is the difference between an implant that merely survives and one that actively promotes healing while resisting the combined assault of wear, corrosion, and infection for the rest of a patient’s life.

Subject of Research: Mechanical surface treatments, corrosion resistance, and tribocorrosion behavior of AISI 316L stainless steel biomedical implants

Article Title: Surface integrity and biofunctional performance of AISI 316L stainless steel implants: the role of mechanical surface treatments, corrosion resistance, and tribocorrosion behavior

Article References: Perez Teixeira, R. L. (2026). Surface integrity and biofunctional performance of AISI 316L stainless steel implants: the role of mechanical surface treatments, corrosion resistance, and tribocorrosion behavior. Frontiers in Biomaterials Science, 5, Article 1913354. https://doi.org/10.3389/fbiom.2026.1913354

Image Credits: AI Generated

DOI: 10.3389/fbiom.2026.1913354

Keywords: AISI 316L stainless steel, biomaterials, surface integrity, mechanical surface treatments, corrosion resistance, tribocorrosion, passive film, orthopedic implants, osseointegration, surface engineering, PRISMA review, biocompatibility

The coating, dubbed Ag-Zeo by the team, begins with an unlikely raw material: metakaolin derived from halloysite clay nanotubes, a natural aluminosilicate precursor. Conventional ZSM-5 synthesis relies on organic structure-directing agents such as tetrapropylammonium hydroxide, chemicals that are expensive and environmentally unfriendly. By substituting metakaolin, Ludox silica, silver nitrate and a small amount of ZSM-5 seed crystals, the researchers avoided organic templates entirely. The polished steel coupons were cleaned, aged in the zeolite sol for 48 hours, and then crystallized in a high-pressure reactor at 175 degrees Celsius for two days, allowing zeolite crystals to nucleate and grow directly on the metal surface without any binder.

Characterization confirmed that the coating is the real thing. X-ray diffraction revealed the hallmark reflections of the MFI-type ZSM-5 framework, including the intense peak near 23 degrees two-theta, alongside weaker peaks at 38.1 and 44.8 degrees corresponding to face-centered cubic metallic silver. Nitrogen adsorption measurements showed a Type I isotherm typical of microporous materials, with an exceptionally high BET surface area of about 474 square meters per gram, a pore volume of 0.26 cubic centimeters per gram and an average pore diameter of 2.24 nanometers. Scanning and transmission electron microscopy captured the classic coffin-shaped micron-sized ZSM-5 crystals, roughly 1.21 micrometers across, deposited as a thin, homogeneous film of one to five percent by weight on the steel.

Perhaps the most important structural finding is that silver was incorporated into the zeolite framework rather than simply sprinkled on top. Diffuse reflectance ultraviolet-visible spectroscopy identified three distinct silver species: isolated Ag-plus ions absorbing near 210 nanometers, sub-nanometer silver clusters near 290 nanometers, and metallic Ag-zero nanoparticles showing a surface plasmon band at 418 nanometers. Fourier-transform infrared spectroscopy showed the preserved five-membered ring vibration at about 545 wavenumbers, while shifts in the silicon-oxygen and aluminum-oxygen stretching region between 970 and 1220 wavenumbers pointed to genuine isomorphous substitution. Energy-dispersive X-ray mapping confirmed silver at 1.03 percent by weight, uniformly distributed alongside silicon, aluminum, oxygen and sodium throughout the crystals.

On the coated implant, elemental mapping told an equally encouraging story. Signals from iron, chromium and nickel revealed the underlying alloy, while silver, silicon, oxygen and aluminum confirmed a continuous zeolite layer above it. Because the coating is thin, the electron beam still interacts with the substrate, indicating intimate contact between the two. The researchers argue that this uniform integration matters biologically: silver locked into the framework leaches slowly and evenly, avoiding the concentration spikes that plague surface-deposited nanoparticles, while the microporous architecture can wick up biological fluids and improve interactions between the implant and surrounding tissue.

Corrosion testing in a brutal acidic chloride bath, one molar sodium chloride at pH 1.0, showed the coating earning its keep. Bare stainless steel started with a corrosion current density of 0.014 amperes per square centimeter, which climbed to 0.046 within days as chloride ions attacked the passive chromium oxide film. The Ag-Zeo coated samples moved in the opposite direction, with corrosion current falling from 0.03 to 0.021 amperes per square centimeter over five days of immersion, a sign that the coating-substrate interface was stabilizing rather than degrading. Electrochemical impedance spectroscopy reinforced the picture, showing larger semicircles and higher charge-transfer resistance for coated samples, consistent with a barrier that limits ion diffusion to the metal.

The drug delivery results may be the most clinically provocative. Cisplatin, a platinum-based chemotherapy used against osteosarcoma and other cancers, was loaded into the zeolite with an encapsulation efficiency of 88 percent and a loading capacity of 4.4 percent. When the loaded coating was tested across a pH gradient, it behaved like a smart material. At pH 5.6, which mimics the acidic microenvironment of bone tumors, cumulative cisplatin release climbed steadily to about 15 percent over 72 hours. At physiological pH 7.4, release was slower, reaching only about 10 percent in the same period. Crucially, the profile showed gradual, sustained liberation rather than the dangerous burst release common to many polymer carriers, a behavior the team attributes to host-guest interactions inside the zeolite channels and to a synergistic effect between silver and the platinum complex.

Antifungal performance rounded out the platform’s credentials. Implant-associated Candida albicans infections are notoriously difficult to treat because the fungus builds resilient biofilms that resist azoles, polyenes and other standard drugs. In adhesion assays using Candida albicans ATCC 14053, surfaces treated with Ag-Zeo at 16 milligrams per milliliter showed dramatically fewer adherent, viable fungal cells than untreated surfaces or surfaces treated with zeolite alone, which performed no better than the control. That comparison isolates silver as the active agent, delivered steadily from its zeolite host. The authors point to the established mechanisms of silver action, including reactive oxygen species generation, oxidative and nitrosative stress, membrane disruption and interference with microbial proteins and DNA, all sustained by the controlled ion release that the framework provides.

Taken together, the study sketches a next-generation implant surface that is simultaneously protective, therapeutic and antimicrobial, all from a clay-derived, template-free synthesis that the researchers describe as a sustainable strategy for implant coating technology. The work remains at the laboratory stage, and questions of long-term biocompatibility, mechanical wear and silver dosing in living patients will need to be answered before clinical translation. But the concept, a single green coating that resists corrosion, fights fungal colonization and dispenses chemotherapy on demand in response to tumor acidity, offers a compelling glimpse of where biomaterials engineering is heading: away from passive hardware and toward implants that actively participate in their own defense and in the treatment of the diseases that put them there.

Subject of Research: A green-synthesized silver-integrated ZSM-5 zeolite coating on AISI 316 L stainless steel implants for corrosion resistance, controlled cisplatin delivery and antifungal activity

Article Title: Sustainable silver-integrated ZSM-5 coating on AISI 316 L implants: a multifunctional platform for controlled cisplatin delivery and antifungal activity

Article References: Sustainable silver-integrated ZSM-5 coating on AISI 316 L implants: a multifunctional platform for controlled cisplatin delivery and antifungal activity. (n.d.). https://doi.org/10.1007/s44442-026-00108-3

Image Credits: AI Generated

DOI: 10.1007/s44442-026-00108-3

Keywords: zeolite coating, ZSM-5, silver nanoparticles, AISI 316L stainless steel, cisplatin delivery, antifungal activity, Candida albicans, corrosion resistance, hydrothermal synthesis, metakaolin, drug release, biomaterials